Dark matter, the mysterious unseen mass, and dark energy, the universe’s mysterious force, comprise the rest of the unknown universe. We still know very little about dark energy and dark matter. Dozens of institutes and thousands of scientists have organized international collaborations in search of both. In fact, scientists hope the biggest energy particle collider [1], the Large Hadron Collider (LHC) in Geneva, will help solve the puzzles of dark energy and dark matter.

            It is common for people to ask, how did the universe begin? After decades of observing and measuring, today the majority of scientists explain the beginning of the universe via the Big Bang theory. Two astronomers, Arno Penzias and Robert Wilson, established the Big Bang theory of cosmology by observing the cosmic background of radiation [2]. According to their theory, everything in the universe was contained in one single mass and there was no space or time. Everything started with the explosion of this extremely dense and hot mass. This explosion was not like an explosion into an empty space; rather space itself began with this explosion.

The idea that led scientists to the Big Bang came from observing the universe’s expansion. Edwin P. Hubble found that almost all galaxies are moving away from the center of the universe [3]. He did so by measuring the light from these galaxies to determine their velocities. This proved that the universe was not static, but was instead expanding. After scientists realized that the universe is expanding, they thought that there must be a beginning to this expansion. Then, using the speed of this expansion, they calculated the life of the universe. Through this, they were able to show that the universe has a beginning. Today, almost every scientist agrees with the Big Bang, and they can support it with scientific evidence.

The idea of the universe, let alone an expanding universe, can be pretty incomprehensible. Let me make it a bit more comprehensible. Think about a balloon. There are two spots marked on this balloon. When you inflate the balloon, you’ll see how these two spots are moving away from each other. The balloon is the universe and the two spots are matter in that universe. This example shows how matter “rides” the expanding universe.

Until about 20 years ago, most scientists thought that the expansion of the universe was getting slower. In 1998, observations of the Type la supernovae revealed the existence of dark energy. Dark energy, scientists found, was one way to measure the expansion rate of the universe over time. This discovery was proof for the universe expanding at an increasing rate. Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess have been awarded the Shaw Prize in Astronomy in 2006 [4] and Nobel Prize in Physics in 2011 [5] for their breakthrough study on this topic. But though scientists know the universe is expanding faster and faster, no one yet knows why.

Let’s go back to the beginning of the universe and see how everything was induced into a perfect order. At the beginning, when the Big Bang (BB) occurred, one might think that this came with chaos and disorder. The perfect design of the universe came from that mess.

If we could get precise information all the way back to the Big Bang, it would help us to solve many outstanding mysteries. Unfortunately, we are unable to gather this information because the cosmos, in its infancy, was foggy and full of light rays. After about 300,000 years, the universe became transparent and many particles fell away; the furthest distance we can see across space is 13.7 billion light years, which is when the universe became transparent.

Cosmic Microwave Background (CMB) was formed almost 380,000 years after the BB. That is the cosmic background radiation, or thermal radiation, and it is believed to be a leftover from the BB. The CMB is the source of the oldest light in the universe and it represents the kernel of stars and planets.

In the early stages of this CMB time, elementary particles were formed. These particles acquired mass while passing through the Higgs field and interacting with the Higgs boson [1]. These particles are mainly divided into two categories: fermions and bosons. Fermions are the most fundamental particles, known as quarks and leptons. The quarks and leptons are further divided into six flavors and corresponding antiparticles. Bosons are photon, gluon, W-Z bosons, and graviton. They carry forces, included the four main forces in the universe – electromagnetic, strong, weak, and gravitational.

The basic building blocks of matter are two composite particles, baryons and mesons, which are formed by the combination of quarks. Baryons are made of three quarks, such as protons (two up and one down quarks) and neutrons (two down and one up quarks), of the atomic nuclei. Mesons are usually found in cosmic rays and are composed of quark-antiquark pairs. Today, more than 200 subatomic particles have been discovered at sophisticated particle accelerator laboratories. Most of them are composite particles, composed of other fundamental particles.

After the creation of these elementary particles, stars, galaxies, and planets were formed, step-by-step.

First stars: 200,000,000 years after Big Bang
According to the results of NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), the first stars were formed 200 million years after the BB. The clumps of matter were brought together with the gravitational force and they grew like a growing snowball until they have enough energy to start nuclear fusion process, which is the main process behind the shiny stars up in the sky.
First Galaxies: 1,000,000,000 years after Big Bang

1.6 million galaxies have been identified according to the location of the Milky Way Galaxy by The 2 Micron All-Sky Survey (2 MASS). Figure 1.1 is a computer-generated map of our surrounding universe by the 2 MASS, which shows nearly 50,000 galaxies near our galaxy, Milky Way (2 MASS/ J. Carpenter, R. Hurt & T. H. Jarrett).

The Milky Way, which includes our solar system, began to form 5 billion years after the BB. There are approximately three hundred billion stars in our galaxy, and there are estimated to be 100 billion galaxies in the universe. Scientists do not know the structure and features of these galaxies. But then, they don’t even know everything about our galaxy.

How big are objects in the Milky Way? Everyone knows about the moon and the Earth, as well as the other planets in our solar system. The largest star in the Milky Way is VY Canis Majoris, a Red hyper-giant. It has a diameter of 280 million km, which is so big that an airplane flying at 900 km per hour would need 1100 years to circle the star. There are approximately 200 billion stars in Milk Way alone and the sun is only one of them.

When thinking about all the space in our universe, it makes the order of our own solar system and galaxy seem quite extraordinary.

A solar system in general consists of a star at the center and rotating astronomical objects (planets, moons, etc.) around that star. In our solar system, the object in the center is the sun and everything orbits around it. There are eight planets including the earth and their natural satellites orbiting the sun. So far, 3946 comets, many asteroids, and thousands of near-earth objects and minor planets have been discovered [6] around the sun. The sun is attracting all these objects with the gravitational force and they counter this attraction by means of their centrifugal force. These forces are balanced and keep the objects in their orbits. All of these are formed and located perfectly with a magnificent balance. How does this kind of order form from a disorder spontaneously?

References:

[1]       Kara, Cihan, "Will CERN Reveal the Origin of the Universe or Cause the End," The Fountain Magazine, Issue 92, 2013.
[2]       The Large Horn Antenna and the Discovery of Cosmic Microwave Background Radiation,             https://www.aps.org/programs/outreach/history/historicsites/penziaswilson.cfm
[3]       Hubble Space Telescope,             https://www.spacetelescope.org/about/history/the_man_behind_the_name/
[4]       The Shaw Prize in Astronomy in 2006,         http://www.shawprize.org/en/shaw.php?tmp=3&twoid=51
[5]       The Nobel Prize in Physics 2011,      https://www.nobelprize.org/nobel_prizes/physics/laureates/2011/
[6]       The Minor Planet Center: http://www.minorplanetcenter.net/

In order to find answers to these questions, let’s consider ourselves sitting at home after a long, tiring day. Are we aware that we are moving very fast even at a moment when we seem to be resting? When we travel by bus, we are motionless from the standpoint of a sitting passenger, yet have a velocity compared to an outsider standing on the sidewalk. The trees lining the road seem to be going backwards, but they are fixed to the ground with no speed. Therefore, velocity is relative and we in fact move at different speeds while sitting at home depending on the objects of reference. We have a zero velocity relative to our guests sitting with us on the couch, but have various speeds compared to the center of Earth, the moon, the sun and the center of the Milky Way galaxy. Not only us, but all existence in the universe has a movement, or oscillation. This movement is usually in the form of a revolution for objects of important mass and as a vibration for particles with smaller masses.

The shining celestial bodies of the cosmos rotate around themselves like whirling dervishes. They revolve around other heavenly bodies or around their common center of gravities, such as pilgrims revolving around Ka’ba in Mecca. The gravitational force set in the universe pulls all objects towards each other. This gravitational force indeed pulls all masses together; however, it is counterbalanced by the motion of revolution given to grand heavenly bodies. As a matter of fact, everything is moving: a solar system with its planets, moons, and comets; the Milky Way galaxy, along with billions of stars, nebulas, galaxies, interstellar dust, gas clouds, and other celestial objects… all are moving in a giant rotating motion like a carousel. In this article, you are going to find some of the scientific findings of our revolving planet, the sun, and the universe, and how some verses in the Qur’an sound miraculously relevant to them.

The Earth’s motion

First of all, we have a velocity stemming from the Earth’s rotation. People living on the equator travel approximately a thousand miles per hour in reference to the center of the globe due to this rotation. While people on the poles never gain any distance over 24 hours, people on the equator travel nearly 23,800 miles! Inside a plane, because we move at the same rate as the plane, we cannot feel its speed. In a similar way, since we move at the same rate as Earth, we cannot feel the globe’s movement.

There are many benefits associated with the Earth’s rotation. The delineation of day and night, atmospheric jet streams, oceanic currents, and similar events rise from the rotation of Earth around its axis. For instance, it causes the warm water currents of the Gulf Stream to reach England, generating a warm and rainy climate.

There are verses in the Qur’an that point to the globular shape of the Earth and its rotation around its axis and revolution around the sun:

“He has created the heavens and the Earth with truth. He wraps the night around the day, and He wraps the day around the night. And He has made the sun and the moon subservient (to His command), each running its course for a term appointed (by Him). Be aware! He is the All-Glorious with irresistible might, the All-Forgiving.” (Az-Zumar 5)

Yet another verse furthers this point:

“It is He Who has created the night and the day and the sun and the moon. Every one (of such celestial bodies) floats in its orbit.” (Al-Anbiya 33)

The verb “wrap” is usually used for round objects, and the perpetual arrival of day and night are only possible with a circular planet. The Earth’s rotation leads to different days, on the micro level, and different seasons, on the macro level. The Qur’an concisely summarizes all these physical events with the simple phrase, “wrap the night around the day.”

The Earth’s primary motion is around the sun. We are roughly 93 million miles away from the sun and we make this orbit, which is nearly 584 million miles, every 365 days. According to the center of the sun, our average velocity on this orbit is approximately 66 thousand miles per hour.
In addition, other planets travel around the sun via different orbits and speeds, each moving on a separate plane. For a moment, it is significant to visualize the sun, which is more than a million times larger than Earth, with its planets and other viscera revolving around it via no visible bond between them.

The movement of the sun

As stated earlier, when we travel on a bus, we observe the trees and buildings near the road going backwards even though we are the ones moving. In a similar way, we see the sun as revolving around us, though in fact the Earth is the one moving. In the Qur’an, the chapter of Al-Anbiya, the verse reading, “each running its course,” is about the creation of the sun and moon, clearly pointing to their movements. Unfortunately, the verse that reads, “A(nother) clear sign for them; And the sun runs the course appointed for it for a term to its resting-place, for the stability of it(s system)…” (Ya Sin 38) was misunderstood as the sun revolving around the Earth. However, we know today that our sun is one of a couple hundred billion stars in the Milky Way galaxy. As such, it both rotates around itself and revolves around the center of the Milky Way galaxy, and confirms the miraculous declaration of the truth in the verse.

In addition, the sun also has a secondary movement inside the local star cluster towards a certain direction. We can explain this with an example: the atmosphere is in motion along with the Earth. Each particle and particle set that makes up the atmosphere not only moves right and left, but also has a total revolution around the Earth. The sun behaves in a similar way within the star cluster and around the center of the Milky Way.

How are we going to define the velocity of the sun? We can determine the sun’s speed by referencing a constant point depending on the average velocity of stars in the section of the galaxy that we inhabit. The sun, according to a local constant point, travels towards the shiny Vega star in the Lyra constellation with an average speed of 43 thousand miles per hour.

Apart from their individual movements, the stars in our galaxy also revolve around the galactic center. The velocity of this movement depends on the star’s mass and its distance to the galaxy’s center. The sun completes one loop inside the Milky Way galaxy every 225 million years. It has completed a total of 20 tours around the galaxy’s center since the Earth’s creation. Our Earth, which moves along with the Sun, travels around the galaxy’s center at nearly 492 thousand miles per hour.

The motion of the Milky Way galaxy

Our galaxy is one of the billions of galaxies in known space. Galaxies are the biggest known structures. The universe expands and galaxies move away from each other, conforming to the meaning of the verse, “And the heaven, We have constructed it mightily; and it is surely We Who have vast power, and keep expanding it” (Adh-Dhariyat 47). Our galaxy, along with nearby galaxies, is pulled towards the Leo and Virgo constellations. The cause of this attraction is not understood yet.

Since all galaxies are moving, how can we determine the velocity of the Milky Way galaxy? As is known, the entire universe is filled with cosmic radiation as a remnant of the Big Bang. When this radiation is taken as a reference, the Milky Way travels at around 1.3 million miles per hour.

At the moment, when we think we are sitting in place, we are actually moving around the center of the Earth, sun, our local star cluster, the center of the Milky Way galaxy, and also moving away from other galaxies. We have velocity in relation to all of these movements. The revolution of the universe is also a fact verified by the Divine word: “I swear by the heaven ever-revolving” (At-Tariq 11).

By the time you finish reading this sentence, you will have been carried over the earth, passed the sun, and moved through actual space of 1000 kms! In the time it takes you to ponder upon this, you will have moved another 1000 km through real space. Fast isn’t it? This is the speed at which one arm of our galaxy moves through space every second, and we don’t even feel a thing!

The motion of stars in their dedicated orbits, black holes, nebulas, and infinite number of other phenomena in the outer space display spectacular and equally thoughtful exhibitions thanks to Hubble and other new technologies. An increasing number of studies are thus devoted to stars, supernovas and interstellar space in recent years. Our contemplation of the universe deepens as we accrue more knowledge about it. Just as a cell is the functional building unit of the body, the main building blocks of the universe are galaxies. Just like every other living thing, galaxies will not be around for eternity; they form, develop, and cease within the cosmic laws that are put in place by their Creator.

According latest findings, it is estimated that around 100 billion galaxies exist in the observable universe and that there are galaxies 100,000 light years in size. A year has 31,536,000 seconds. Light travels 300,000 kilometers per second, therefore one light year equals to 946,080,000,000,000,000 (quadrillion) kilometers. Apart from the dispersal of stars, intergalactic distances of galaxies are not much bigger than their own galactic size. For example, the big Andromeda galaxy (the galaxy which is the closest to us) appear from the earth as wide as the sun or moon in the sky and can even be noticed with the naked eye. Latest research in astrophysics revealed that stars are not dispersed equally but rather found together in galaxies as an open system that exchanges energy and matter with its surroundings. A big portion of the galactic space is filled with gas and dust clouds which enable such exchanges to take place. This interstellar stage in which stars are born and die bears vital importance in sustaining and maintaining a galactic presence.

Some amazing characteristics of galaxies

Stars with different masses exist in a galaxy. Smallest one can be one tenth of the Sun’s mass whereas the biggest can be 100 times bigger than the sun. The most important feature of a star in a galaxy is its mass. Brightness of stars increase with their mass and this relation is three dimensional (cubic mass). Therefore if a star is twice as big, it is eight times brighter. Another feature is the relation between the age and mass of a star. The bigger the star, the shorter its life. These big stars live shorter compared to smaller ones despite their giant fuel reserves because they consume it very fast. Similar relations can be observed in the human body, which is an index of the universe, such that overweight people who consume more calories than people with less calorie intake eventually consumes more energy and become subject to deterioration in health and faster aging. The lifespan of a star is inversely proportional with its square mass (1/m2). For example, if a star is twice as massive, it lives only for one fourth of the time. Calculations show that our sun has a lifespan of 10 billion years. Compared to this, if a star is 30 times bigger than sun, it will only live for 10 million years.

The timescale of events that are occurring in galaxies can vary from thousands of years up to millions of years. Time required for the creation of a star is perhaps like a day in a galactic scale. This long time frame is considered short when compared with the age of galaxies. Furthermore, verses in the Qur’an (Al-Ma’arij 70:4) open new horizons in this matter and point out to the fact that time can change depending on different ratios and scales; so a day can indeed vary in length from being 1000 years or 50,000 years.

The movement and behavior of galaxies are quite complicated. Such that even if the galaxy formation process is completed, the creation and expiration process of stars within the galaxy still continues. It takes tens of thousands of years for a gas cloud to collapse inwards under its own gravitational force and become a star under normal conditions. Even five-ten billion years after the creation of a galaxy, it amazes scientists that there is still plenty of gas to remain in the interstellar stage, enough for a star to be born. On the other hand there are galaxies in which star formation is much faster than our Milky Way galaxy. These galaxies are called “starburst” galaxies and new stars are created in variable speeds over a long period of time. The uniqueness that is observed in the specific characterization of animal and plant species can also be witnessed in the creation of stars at different speeds, making spiral galaxies even more mysterious. This is because while a steady and balanced speed in the creation of stars is maintained in spiral galaxies, all the gas and dust available is consumed for the formation of stars in other galaxies. In a galaxy where stars continue to be created, the regions where large stars are created can be observed better compared to other regions in the night sky.

Spiral galaxies

Galaxies are generally divided into three groups: irregular shaped, elliptical, and spiral. Irregular shaped galaxies are composed of many young stars, gas and dust clouds without a definite shape. Elliptical galaxies are made up of old stars and limited number of gas and dust clouds. They are created in different shapes such as round, flat or like a baseball. Spiral galaxies are in the shape of a disc composed of spiral arms extending out of the center as they rotate. Solar system is located inside such a spiral-like galaxy. In these types of galaxies, stars contain spiral signatures. Bright spiral arms found in many images taken of galaxies generally show star forming regions and not the locations of the stars themselves. That is why the exceptional quality of spiral galaxies is hidden in the continual formation and expiration process of stars. Spiral displays which show star creation regions do not revolve along other stars in the galaxy. However spiral galaxies do exhibit a special rotation. Observations point out that spiral signature within the galaxy deteriorates gradually and reshapes in a slower fashion than the galaxy rotation speed. With these new findings, it is possible to say that it is more appropriate to understand galaxies as dynamic systems which change in time instead of being static under the constant and instantaneous intervention and control of the infinite power and wisdom of the Almighty.

One of the most impressive features of spiral galaxies is that the regions where stars are created in the main spiral contain new sublevel spiral patterns. Just like clouds, it is possible for different spiral forms to be created. Sometimes very symmetric spiral arms or rectangular stick-like formations via extensions of spiral arms along with regular spiral looking shapes are generated. Despite this spiral variety, when observed from outside, stars are seen to be surrounding a flat disc and forming together as a giant globular halo. This halo was generated billions of years ago from short and longer aged stars. It is the dimmer region of the galaxy yet this halo is considered to contain most of the galactic material. Stars are located in a fashion that resembles a disc in this halo of dust and gas. The layer of dust slowly rotates around an axis that passes through the center of the halo. This rotation is not coincidental; it is controlled in such a way that the speed of stars nearby do not differ in the rotation speed of the whole disc any more than 10%. In other words, the disc does not have a constant speed. It exhibits flexibility and variations from within. Stars and gas clouds are made to revolve in similar average speeds no matter how far they are away from the center. These notions are confirmed with the use of motion laws that Newton discovered and named after himself.

Numerous types of stars from different age and mass groups exist in the disc section of a galaxy. The age of stars is determined by analyses of the light spectrum that they emit. According to the results from these analyses, the creation speed of stars has been found nearly constant around the disc section in a spiral galaxy. In many galaxies, disc material has been discovered to be around 10% gas and dust cloud and that 80-90% of the rest remains outside the disc in an invisible form, unlike stars and gasses. This is because it absorbs the majority of the light to be reflected. This kind of material is called “dark matter.” It is thought to be a very old black hole, with expired stars or an extremely cold dust cloud or a combination of these. Aside from this, it has been discussed that they are created from neutrinos or undiscovered particles. According to common notion, dark matter as generated by expired stars in the galaxy does not have any relation to the movement of spiral galaxies and their kinetic behavior, it only has gravitational effects.

Gas cloud in the disc is not dispersed proportionately; instead, it is collected in a thin layer. Furthermore, it is understood that these clouds are composed mainly of carbon, silicon, iron and many other elements, and these particles get ripped from surfaces and flown around via star winds or thrown towards interstellar space. Surprisingly, the interstellar space is a scarcely populated place. Even in areas that are considered to be empty, one atom exists in 1,000 cm3, and it can vary from one million atoms to a couple hundred per cm3 in denser regions. The density of interstellar spaces from the highest to the lowest can vary within a factor of a billion. This ratio is much greater than the density difference between air and a piece of rock.

Systems established without thermal equilibrium

Interstellar space is not in a state of thermodynamic balance. Very sizable molecular clouds are constantly shaped and get scattered into the medium. This way material exchange is carried out in between different phases on a smaller scale. Maintenance of a system where different components are preserved in a stable state with no equilibrium is a mystery to all. This elusive phenomenon has been studied by both physicists and chemists for the last 40-50 years. Data obtained so far recommends that two processes are particularly used to establish and maintain stable compounds away from an equilibrium state. The first is that such systems should include material recycling mechanisms between different components. Second is the regulation of processing speed with feedback. These two events should be executed with a balanced fashion so that the amount of material in each composition does not change. Thus, these two phenomena are executed in the most finely calibrated manner in spiral galaxies that can never be possible out of coincidence.

Plasma, one of the phases of matter, is about a couple million degrees Celsius. However, it is a much diluted phase; only one atom exists in a volume of 1,000 cm3. Temperatures rising to these levels are made possible by the energy provided from supernovas. A supernova explosion releases such energy into the space that it forms a hot gas cloud and this starts to expand. This gas cloud releases its electrons into its surroundings as it dissipates. A phase of diluted hot plasma in a bumpy shape is generated as gas cloud expands throughout the matter. One of the reasons that interstellar space took so long to be discovered is because we are still located in a hot bubble. This bubble has a magnitude of 300 light years. Studies so far have mapped this bubble and discovered it to have an irregular shape.

Aside from this, recently a new neutron star was discovered and this star is thought to be remnant of a supernova explosion that created this bubble. It should not be surprising that we are located in such a hot bubble because this only occupies 70% of our galactic disc volume. A supernova is created once every 30 or 40 years in our galaxy. Supernovas have the task of supplying the energy needed to keep the entire interstellar space under a constant pressure. It is an incredible phenomenon to ponder that a habitable planet exists in the depths of a cold space.

Interstellar spaces resemble an ecosystem from a standpoint of events that are taking place inside it. Each galaxy could be viewed as a dynamic system where stars are constantly born and extinguished in the presence of a determined cycle of energy and matter. Events that are executed with Divine wisdom in these heavenly systems (galaxies, stars, interstellar spaces) testify in their own languages to their Creator who fashioned them in the form of an art with wisdom and generously. Galaxies behave as if they are living organisms; they are born like humans and they die like humans. Continual composition and decomposition of galaxies with their contents stand as major proof to the cosmos of present and absent worlds. The heavens and the earth, the stars and galaxies all make up the Divine canvas painted and repainted on the easel of God’s command: “Be and it is.”

References

• Smolin, Lee. 1997. The Life of The Cosmos, Oxford University Press, New York.
• Syed, Ibrahim B. 2003. “Understanding String Theory,” The Fountain, Issue 41, January-March 2003.

Galaxy and the Sun

The 21 cm long radio wave radiation emitted from the hydrogen gas within the dense dust and gas clouds of the arms of the galaxy enables us to know about the structure of the galaxy. This information led us to conclude that our galaxy is indeed not a solid object and displays a circular motion of 250 km per second. The Solar system is estimated to complete one revolution around the galaxy in approximately 200 million years. At this point the critical question that comes to mind is how a solar system orbit is maintained and protected during these journeys where the solar system bypasses the gravitation and effects of strong heavenly bodies without causing disruption and collisions. The Earth just won’t become a habitable place only by considering planetary solutions. We may have to consider measures regarding our solar system and other galaxies, since the solar system has a very sensitive relation with the other heavenly systems in our galaxy.

The Sun’s position in the Milky Way

Trillions of comets in the Milky Way galaxy fill the outer space and encompass the solar system in a globular fashion. One of the comet groups orbiting the solar system is called Oort or Opic-Oort cloud. A hundred billion comets is estimated to exist in the Oort cloud.

These comets follow the designated orbits until they deorbit with gravity of another strong heavenly body other that the sun. Stars and masses of the Milky Way constitute a globular center with spiral arms where these arms extend out of the center in the same galactic plane. There are a limited number of systems located in the space between these spiral galactic arms. In fact, this is where our solar system exists. In other words, it deserves attention that the sun does not reside in the dense centric part of the galactic arm Orion (Hunter) but exists in the nearby sparsely populated galactic mid space. The solar system that has been placed in the most appropriate position within the Milky Way also needs to be protected from possible dangers it may encounter (like crossing paths with dense spiral arms) during its journey around center of the Milky Way.

Scientist who study the place of our solar system in galactic maps particularly point out that we are far away and safe from the devastating effects of cosmic storms.

If the solar system did exist in the arm where stars are densely populated and near each other, gravitational forces could result in changes in planetary orbits. For instance, in the spiral arms of the galaxy, comets would easily deorbit and bombard the earth momentarily under the strong gravitational force of these arms. Yet remarkable measures have been taken to protect against this as well! One of them is the velocity value of the Sun. For example, in order to provide an effective communication, a satellite positioned in the earth orbit is given a speed equal to the one earth has for rotating around its axis. Our sun is given a suitable velocity to move with almost the same speed of galactic arms without intercepting each other, thus providing a safe passage. However this is not the case in 95% of the stars and the spiral arms in our galaxy unlike the one determined for our solar system. This is something to reflect and think about. Another measure that prevents the sun from intersecting with the spiral arms is that it has a circular orbit rather than in the form of an ellipse like stars of the same age. Also in this regard, we observe that our sun is given a special movement allowing Earth to become a habitable place for life. The All-Wise and All-Mighty Creator works the galaxies just like a giant machinery wheel with his established laws.

The stars in the spiral arms may in time get sucked into the inner parts of the structure, not being able to hold on to their position for a long period of time. This is also applicable for the sun. Divine measures also intervene here and leave the sun in the protective zone. The sun is located in the “galactic common rotational radius” where strong spiral arm effects do not exist. Furthermore, when Supernova explosions take place, giant star debris can reach a couple thousand light years away, enabling the sun not to be negatively affected from these explosions since it exists in the outer regions of the arms.

Cosmic dangers in the galactic center

The solar system is 28,000 light years away from galaxy center. If our galaxy is considered to be 200 thousand light years wide, one can say that we are relatively close to the center.

This location in the galaxy is distant enough to be protected from the negative effects that could arise from the galaxy center. What would happen if the solar system was closer?

In this case we would constantly be exposed to dangerous gamma, X-ray, and cosmic radiations, therefore no life on Earth! Not to mention the black hole in the galaxy center which has a mass 3 million times as much as the sun. If the sun were to exist near the black hole, life on earth would again be negatively affected from the strong gravity of it. The extraordinary measures that have been taken for our solar system, the sensitive adjustments that are put in place, and the maintenance of such balance and complexity all displays a perfect science and a Divine power in the background. All these events demonstrate clearly that no single event of randomness and chaos exists in the universe. The most complicated and sensitive tasks are resolved in the best possible way, therefore revealing a perfect organization. We see this perfect organization between the Milky Way, the solar system and the earth!

Reference

Mishurov, Y.N. and L.A. Zenina. 1999. Yes, The Sun is Located Near the Corotation Circle. Astronomy & Astrophsica 341: s. 81–85.

Introduction

Human beings have wrestled with questions about the origin of our existence and the fabric of our universe for thousands of years. This questioning formed the discipline of cosmology. Dr. Natarajan explores the nature of our world and shares her perspectives about how new scientific discoveries are reshaping our understanding of the universe and our place in it. Until very recently, the universe had been considered a vast empty space. But the Dark matter theory states that the universe is not empty, but rather filled with an invisible matter. As new mysteries unfold, Dr. Natarajan points out that it is our fundamental human curiosity that leaves us no choice but to explore the universe and how we fit into its grand picture.

M&B: Dr. Natarajan, you work on dark matter in the universe. What is the theory?

It turns out that the bulk of the matter in the universe is not made of ordinary atoms that you and I or the universe that we know and experience is made of, but instead made of this mysterious particle. Ninety percent of all the matter in the universe is dark matter, and we believe this is a set of particles that was created very early in the universe. These particles do not have charge, but they have mass. Since they dominate the mass of the universe, it turns out that they really form the scaffolding in the universe around which all galaxies, stars, and so on, form. They are sort of the basis or the framework within which normal atoms actually cool to form star galaxies, and then have generated us.

M&B: What is the evidence for their existence?

The reason dark matter remains a mystery, – although there is incontrovertible evidence for the existence of dark matter – is the fact that you only detect it indirectly. What I mean by that is you detect its presence because it has mass, and since it doesn’t have any charge it doesn’t couple to any radiation. So you don’t see radiation in any wavelength in the electromagnetic spectrum: no X-rays, no gamma rays, no visible light, nothing. But since dark matter has mass, it aggregates gravitationally, so they feel gravitational pull towards each other and they cluster. It’s the clustering of the dark matter, the fact that it gets compact, that we detect the effects of dark matter.

M&B: What happens near the regions where dark matter clusters? In your research papers you use the bending of the light rays. How do you observe it?

The primary evidence is the gravitational bending of light produced by these aggregates of dark matter. The universe is really composed of a smooth distribution of dark matter, with a lot of clump regions where this dark matter has aggregated, and then enabled the formation of galaxies. The presence of these large amounts of dark matter causes light from background galaxies coming towards us to bend. The actual shapes of galaxies that are behind a big clump of dark matter, which is along our line of sight, are actually distorted when we see it. The dark matter in general is smoothly distributed everywhere in the universe. But there are these particular regions that are denser. So we can look at regions in which the dark matter is not so densely distributed, look at the shapes of undistorted shapes of galaxies, and then use that to infer how much distortion we’re actually seeing when we see a lump, and infer its existence from the distortion. Because the strength of the distortion is directly proportional to the mass, you can directly infer how much mass there is between us and those objects.

M&B: Is there evidence other than the bending of the light rays?

The other evidence eludes to the fact that dark matter actually gives the basis for the formation of stars and galaxies. If you look at the motions of stars and galaxies, you find that, unlike the solar system, if you look at the velocities of the planets in the solar system as a function of distance from the sun you find that it’s falling. So the planets in the inner regions are moving very fast; they feel the gravity of the sun much more strongly than the outer planets, which are not actually moving as fast. So if you plot the velocity from the center or from the sun outwards in the solar system, the velocities are falling. Whereas if you go to a galaxy and you do the same experiment, you look at stars at different radii and you try to see what their speeds look like. They are speeding up as you go outwards. And the only way they can do that is there is something that is sitting outside the galaxy that holds it up as it were, and has gravity. And it turns out that our current picture is that most galaxies have very extended dark matter halos. The key point is that there’s a lot of dark matter sitting outside the galaxy well beyond where we see the stars.

The other compelling lines of evidence for the existence of dark matter come from larger scale observations of the universe. One of the leftovers of the big bang or relic of the big bang is this microwave background radiation that is detected today in the universe. It was a very hot radiation that has cooled with the expansion of the universe, and we are bathed in it. I mean it’s everywhere, in every direction, and measurements of the directional dependence of the microwave background shows that it’s very uniform. But in one part it’s anisotropic, so there are cool zones and hot zones in the sky. On very small scales we see these cold and hot spots. And these and isotropy’s in the microwave background are exactly predicted by this model, the cold dark matter model, which I said you know is postulated on the very early generation of the universe and these dark matter particles.

M&B: So we know that they exist. But what is their essence? What are their properties?

This is still a mysterious kind of beast. In fact, we don’t know the nature, but it appears that it’s collisionless. It’s very counterintuitive. That’s one of the things I find fascinating about the fact that it is so counterintuitive. These particles are actually collisionless. What that means is that when two dark matter particles approach each other, they pass through each other, they don’t actually bounce off of each other, so these particles don’t collide, which means they don’t have pressure, because pressure is generated by collision. So they are pressureless particles that have mass. Gravity holds them together, but they don’t actually collide.

So a current understanding of dark matter is that it’s definitely generated very early in the universe and that it clusters very strongly and it’s distributed on very different scales in the universe, so there’s like a smooth background and there are lots of clumps on top of it and so on.

M&B: As far as the mass of Dark Matter how much mass are we talking about? If there is no clustering, something like in the volume of the earth, for example, how much total dark matter mass do we have?

Well I guess the thing is at the position of the earth and at the position of the sun from the center of our galaxy. We are not really dominated by dark matter anymore, so dark matter at that radius doesn’t constitute significant portion of the mass. We are bathed in it, but the density is quite low. It’s at the innermost part of our galaxy where the density is very, very high, so we actually expect that the inner most regions of our galaxy is a very complicated, violent place where not only do you have a black hole which we know exists. This is a black hole that is not made of dark matter. This is a black hole that has gobbled gas and grown to about a million times the mass of the sun, and which is sitting at the center and it creates a very violent place for stars because it can rip them apart and so on. And this whole system is sort of embedded in this very, very dense region full of dark matter.

M&B: How is your everyday work? Where do you get data about the light rays coming near the regions with high Dark matter density?

A: I’m a theoretical person and what that means is that I actually build models but models that are guided by observations. The theory has transformed in the past 10 to 15 years because of the amount of data that technological progress has given us.

For example, the Hubbell space telescope has really transformed the kind of modeling that can be done. So I actually use data that other people have procured. They’ve cleaned it up and they give it to me. These are very distorted images of background galaxies whose shape has been distorted because of the huge amounts of dark matter that is contained in a cluster of galaxies.

M&B: The bending of the light rays is predicted by the general relativity theory. Is it what you use for your calculations?

A: It’s a beautiful theory. I think that people really have understood the iconic status of Einstein. What is most fascinating about him for me is the profound insights that he had of such despaired phenomenon. There was a way in which he was able to see connections and synthesize. You know the whole understanding that the geometry, the fate and the contents of the universe ought to be linked is a profound insight. And I think you know it’s incredible that he enabled, you know, his mind enabled him to formulate it in the way that he did, which has allowed people like me to use general relativity and the sort of elegance of general relativity because of how simple it is in fact to apply and test.

M&B: This looks like an intriguing line of work?

I want to stress that this is a particularly wonderful time for cosmology. It’s a particularly special time. I don’t want to use the sort of often abused golden age as it were, but it’s the confluence of technological progress with the kind of data that we can obtain and the level of understanding that we have built up. This is a very special time to be doing this kind of work. And while the mystery of what dark matter might be made of, you know, it may or may not get solved in my lifetime.

M&B: If you want to describe your work, what term would you use?

In a more descriptive way, I guess. What I really do is I build a story line. I build a story line for the universe. I mean, I build a story of the sequence of events of how a structure forms and assembles. The key there is that you are guided, you have a few snapshots, so you have a bit of data, but then you have to extrapolate and you make some predictions. The goal of the kind of work that I do is to make predictions, and have them be taken seriously, to either be falsified or shown to be true, and what’s exciting about this particular time is that people can falsify your theories or your models in a very short time.

M&B: Isn’t it interesting that we can actually make a story out of universe?

Well, I mean, I think that what is fascinating, and this is a personal view, what is fascinating about cosmology is the… you know it’s mystical and it’s mysterious at the same time and it’s highly abstract. It’s not intuitive because the scale that I’m working with in terms of distances, masses, and energy are just unfathomable. So there’s a real irresistible pull for certain kinds of people to do this kind of work. And I think the universe is a pretty good subject for a narrative because of the range of phenomena that occur in it. This is possibly why in all ancient civilizations there is some notion of cosmogony and this idea of fascination with where we came from. I don’t want to sound arrogant by saying that it’s the fundamental question, but you know it’s an inescapable question for anybody to ponder where we came from.

M&B: Is there a sense of awe that motivates you in your studies?

There is a sense of wonder that the universe generates and I think that you know personally for me I’m a bit of an adventurist, and I think if I can imagine myself, if I had been born 200, 300 years ago I would have been one of those explorers. And I think there are people like that amongst us always, who want to explore in different ways. I mean, there are some people who want to explore via music. And there are frontiers that they want to break through in music, and they have the creativity to do that. And I think that for a lot of us who are doing science, and cosmology in particular, there is a sense of exploration, there’s a sense of examining or grappling with things that are really at the limits of our capabilities in a way.

M&B: In some ways one of the most important fruits of the process and coming along it’s our imagination. And the human imagination is also a part of the universe.

Absolutely. It is an inescapable part of the universe and what is fascinating is the idea that we have the capability to even contemplate the origin of the universe given that we are a part of the universe.

M&B: Many people approach science in a utilitarian way and this is not what you are doing.

I think that the fact that it is not utilitarian is precisely what attracts me to it. I think it is the other side of the coin of this, which is why we probably aren’t as well funded and we ought to be better funded than we are, because this is such a fundamental human curiosity. There is enormous public interest in what we do and the level of funding that we have does not reflect that. For instance, obviously medicine is very critical. It’s critical to our existence. But the disparity in how they are funded and how the pure sciences are funded is sort of disturbing. Because I think as a culture, as a world, we can afford to indulge in understanding basic sciences partly because there are spinoffs from all the work that we do. It is unpredictable, and I think that is what’s fascinating. There are no guaranteed benefits to human kind and society today that cosmologists can bring. However, they satisfy this hunger for knowing and going beyond, you know, satisfying your hunger and thirst on a day to day basis.

Mustafa Tabanli is a producer at Ebru TV. He conducted this interview for Emmy Award winning television series Matter&Beyond.

Bio

Dr. Priya Natarajan is a Professor of Astronomy and Physics at Yale University, and an Associate at the Dark Cosmology Center, which is part of the Niels Bohr Institute at the University of Copenhagen, Denmark. Her research interests include cosmology, gravitational lensing, and black hole physics. She earned a B.A. degree in physics and mathematics at M.I.T. and her doctorate at the Institute of Astronomy, University of Cambridge in England, where she was a member of Trinity College and elected to a Title A Research Fellowship that she held from 1997 to 2003. She is currently on leave from Yale to take up her Guggenheim Fellowship. She is deeply invested in the public dissemination of science and is currently a member of the Science Advisory Board for the public television series NOVA.

http://www.astro.yale.edu/priya/

One category of galaxies is the spiral; this is dependent on the galaxies’ appearance. The magnetic field of the Sun is also a spiral. Among many things that have a spiral form are the cochlea inside our ears, our navel cord, our fingerprints, the teeth of mammoths, elephant trunks, some spider webs, the horns of some goats, cluster of sunflowers, thousands of types of mollusks, the pattern in which subatomic particles move, plus many more examples. Grapevine shoots, ivy, some microorganisms, and the positioning of some leaves around their branches are in the form of a helix. Nature displays brilliant examples of spiral and helix forms over a wide spectrum, ranging from fossils to galaxies. Below we will discuss some of them:

The Archimedean spiral

Named after its discoverer, this spiral is the geometrical location of a point which moves across a line turning around a fixed point at the speed of q and with a straight angle (Figure 1). The equation for the polar coordinates is p=aq. The distances between the curves are equal. A good example of this type of spiral is the spider web constructed with equal distances from the center.

The Equiangular (Logarithmic) spiral

This spiral type was defined by Descartes in 1638. In an equiangular spiral, any line that crosses the center cuts through all coils of the curve (Figure 2). The equation for polar coordinates is Inr=a.q or r=ea.q. Sea shells and the shells of snails are formed with this spiral.

Fibonacci Numbers and the Golden Ratio

The following numbers, the sequence of which is made by adding the last two numbers together, are known as Fibonacci numbers: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, … In other words, each number is the sum of the preceding two numbers. Let us divide each number with the preceding one and write down the quotients:

1/1=1; 2/1=2; 3/2=1.5; 5/3=1.666…; 8/5=1.6; 13/8=1.625; 21/13=1.615…; 34/21=1.619…; 55/34=1.6176…; 89/55=1.618…

If we continue to divide in this way, we will reach a mathematical constant, i.e., 1,618034, which is known as the golden ratio (φ).

Let us now draw a new geometrical shape with the Fibonacci numbers. Next to a 1-unit side square put another square that has equal dimensions. Then add another square, this time equaling the sum of the sides of the previous two (2 units). As we continue to add new squares with double the units of the previous two we get what is called the Fibonacci or golden rectangle. When we draw an arc from one corner of this rectangle to an opposite corner and continue drawing through neighboring squares, as in Figure 3, we will get a spiral. A good example of this is the nautilus shell. The golden rectangle and the spiral is frequently used in fine arts, architecture, and technology.

The Helix

The space curves that coil around a cylinder and cut through its main axis at a right angle is called a cylindrical helix (Figure 4). An ivy plant climbs a tree in a helix, and a helix is the shortest distance to a certain height. The Selimiye Mosque, Edirne, Turkey, features one of the best examples of helices in architecture. The architect Sinan designed the minarets of this mosque with three balconies, which are reached via different stairs that have no connections between them.

The 3D Archimedean spiral and the Logarithmic spiral (Helico spirals)

Conical helices are the space curves that coil around a right cone and cut through its main axis at a right angle. Sea snails, or limpets, have this spiral shape (Figure 5).

Galaxies and hurricanes

Galaxies and hurricanes are also spiral in shape and they have some similar features. Sharing the Stamp of Unity, the law of which governs the entire universe, both galaxies and hurricanes are affected by major forces, like the force of gravity, angular momentum or rotation.

Spiral galaxies are divided into two categories: elliptical and barred spiral galaxies. Barred spiral galaxies have arms that extend away from the main core (Figure 6).

(As evidence for a people open to belief) We have assuredly set in the heaven great constellations, and We have made it (the heaven) beautiful for those beholding. (Hijr 15:16)

The Nautilus: A wonder of creation

The hard shell of the nautilus has a beautiful logarithmic spiral shape. Each coil is at a distance from the next at an increasing proportional distance, each coil is multiplied by a constant. The chambers in the shell are similar, but they widen in a geometric sequence. It is amazing that calcium carbonate, the material that makes up the shell, can accumulate in such a way so as to comply with this geometrical pattern. In this pattern, the nautilus occupies the least space that is possible, thus losing as little heat as possible. Architects have been inspired by the nautilus to produce designs to use the smallest possible space to contain the most possible room.

The Cochlea

The cochlea in our ears is like a double-ramp tunnel coiled upon itself. Etymologically, the word cochlea comes from a Greek word that means snail. The spiral shape of the cochlea reminds one of sea shells.

Horns

Horns of the sheep and goats have the shape logarithmic spiral; they grow in the form of helicoids, as if coiling around a cone.

The Rose

The leaves of a rose are lined up and shoot out in a spiral shape.

Spirals open for us gateways to thought in our efforts to explore the wisdom and beauty that have been set in motion in the universe and are constantly maintained. Spirals, like other living or non-living objects or beings around us, are exquisite works of art that point to the fact that nothing exists from coincidence. Looking through a telescope to a marvelous galaxy in outer space or examining a sea shell on the beach or holding a rose in the spring may become a rewarding act if we contemplate on their Fashioner, for such “contemplation for an hour is worth voluntary prayer for a year.”

While you are comfortably sitting in your chair or leaning against a pillow reading this article, you are rotating around the Earth’s axis at a speed up to 1000 miles per hour depending on how far you are from the poles. In addition, our planet is revolving around the Sun, in an orbit 186 million miles wide, at a speed of 67,000 mph. The Sun is taking its planets on a ride around the center of the Milky Way. In turn, the Milky Way, where the Solar System appears as no more than a small dust particle, is retreating from some galaxies and approaching others. For example, the Andromeda Galaxy is getting closer to us at a speed of 200,000 mph. And, even if you know all this, the apparent uniformity and order under which these movements occur enables you to feel at peace and to ignore them.

In distant space, new galaxies are being formed and many others are swallowed by mysterious black holes. Old stars collapse and explode to become supernova, or shrink and become little white dwarfs.

On our home planet which looks like a calm, blue marble from the space, atmospheric conditions from above and the volcanic forces from below cause continuous change in the layout of the continents and the oceans. Again, several centuries of scientific discoveries have shown that the continents are in constant motion, colliding on some fronts, and pulling apart in some other places. The theory of plate tectonics tells us that the continental plates float over the Earth and that when they collide, great mountain ranges (for example, the Himalayas) occur. For similar reasons, the Atlantic Ocean widens by four-tenths of an inch every year.

On the surface of the Earth, volcanoes rise and empty their contents as the building material for new lands. The wind and the rivers erode the soil, leveling the heights or causing deep canyons, slowly but steadily changing the layout of the land.

Animals and plants that sustain life on Earth come into existence and then disappear in lives that range from a few hours to several centuries. The plants recycle the soil and the gases and feed the animals, which return back to the soil when they die.

Your body is renewing itself without you being aware of it. Wounds heal, nails and hair grow. You breathe unconsciously and provide oxygen to blood cells that carry energy and nutrients to each and every cell in your body. The cells multiply for growth and renewal. The body fights against unknown intruders by producing its own medicines. The connections between your brain cells are constantly reestablishing themselves to enable you to understand and react to what you read or experience. Numerous decisions are made in the genes in the billions of cells in your body every moment to produce one or another kind of protein, which ultimately determines how your body functions.

The atoms, the building materials of all living or non-living matter in the universe, interact with other nearby atoms or even with atoms that are millions of light years away, reacting to their gravitational or electromagnetic forces. Atoms are bound to their neighbors, forming strong compounds or breaking bounds and releasing energy.

Even inside a single atom that is seemingly stable, a constant movement and renewal continues. The electrons circle the atomic nucleus at one percent of the speed of light. Even though matter in an atom constitutes a negligible part of the observed volume of the atom, the movements and resulting forces form the illusion of solid matter. When you are looking at a solid rock, are you aware that you are looking at an object that is 99.999999999 % empty? While the electrons continue their restless turn around the nucleus, they jump up and down the energy levels. The electrons seem to disappear from one level and reappear at another level without any continuum in between-hence the term “quantum leap.” When changing levels, electrons emit or absorb photons that are the building blocks of light.

The space-time continuum, first explained by Einstein, tells us that we will not be in the same place or at the same time twice. You will have traveled thousands of miles in the universe by the time you have finished reading this sentence.

In summary, everything in the universe, from the little subatomic particles to gigantic clusters of galaxies, is in a constant state of change.

In all this seemingly chaotic rush, there is a hidden order that keeps everything on course. When astronomers inspect the deep skies, they gasp when observing the beauty of celestial objects, like the nebulae structures recently discovered with the Hubble Space Telescope. On Earth, life continues to function on its course. Your body works until it has fulfilled its expected life span. And, despite all the electrons that are flying, disappearing, and reappearing, the book you left on the desk this evening will be there tomorrow morning-unless you have children at home.

It should be clear that any mishap, even for the slightest moment, might render the universe useless. So, why isn’t everything turning into a chaos of colliding, rotting, disappearing particles? What is the force that sets the harmony in the universe? This is best explained by Said Nursi, who wrote a century ago:

“The Glorious Creator of the universe is Self-Subsistent, that is, He subsists, continues, and endures of Himself. All things subsist and continue through Him, they remain in existence and have permanence. If that relationship of Self-Subsistence was cut off from the universe for even the fraction of a second, the universe would be annihilated.”

References

• See “The Great Attractor” at http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/GtAttractor.html.
• Charles Flowers , Instability Rules: The Ten Most Amazing Ideas of Modern Science, John Wiley & Sons, 1st edition, March 15, 2002.
• See “Complete Coverage of the Hubble Space Telescope” at http://www.space.com/hubble.
• Nursi, Bediuzzaman Said, The Flashes, Sozler Publishing, 5th edition, December 1996.

Ancient people, considering it very important to determine Earth’shape, derived two important clues from the night skies. According to Aristotle (384-322 bce), these were lunar eclipses and the North Star. Lunar eclipses occur when the sun, Earth, and the moon line up in such a way that Earth temporarily blocks the sun’s light from reaching the moon while its circular shadow gradually crosses the moon’s face. The North Star appears lower in the sky the further south we go: at the Equator it lies directly on the horizon, at a latitude of 45 it is 45 above the horizon; and at the North Pole it is directly overhead. However, it is not visible south of the Equator.(1) As both of these indicate a spherical Earth, the scholars of that time discarded the idea of a flat Earth.

The more challenging question was how to determine Earth’s size. Eratosthenes of Alexandria (third century bce) had a simple yet brilliant idea: insert a gnomon (a vertical stick) into a level piece of ground. This enabled him to determine noon’s exact time (when the shadow was the shortest). It was also used as a compass, for in the Northern Hemisphere the gnomon’s shadow points north.

But can such a simple device determine Earth’s size? Aswan, located about 500 miles south of Alexandria, sits on the Tropic of Cancer. So, at noon of June 21 (the summer solstice), a gnomon inserted there has no shadow. By doing just that in Alexandria, Eratosthenes found that the angle was 1/50 of a circle’s circumference (i.e., 2p/50). In other words, the angle at Earth’s center corresponding to the arc between Aswan and Alexandria on Earth’s surface is 1/50 of a circle’s circumference. Since the distance between Alexandria and Aswan is 500 miles, Earth’s circumference should be 25,000 miles, which is its actual circumference.(2) Thus, Earth’s size and shape was pretty well established over 2,000 years ago.

This knowledge was lost to Europe when the ancient civilizations crumbled. But Islamic civilization and culture, which was rising at roughly the same time as the West was declining, produced scholars and scientists who translated and refined quite a bit of this ancient knowledge. For example, in 1424 al-Kashi used Archimedes’ method of computing to determine its values to 16 decimal places. Ulug Beg compiled the greatest star catalog known at that time. During al-Ma’mun reign (813-833), al-Khwarizmi measured one degree of latitude on Earth’s surface and obtained the result of 57 miles. This means that Earth’s circumference is 360×57 = 20,520 miles.(3) Thus, in the ninth century, Muslim scientists knew that Earth was spherical and had a good idea of its size. Most Europeans at that time, believed that Earth was flat and the universe impenetrable.

The Qur’an describes Earth’s geographical shape and change in that shape: Do they not see how We gradually shrink the land from its outlying borders? Is it then they who will be victors? (21:44).(4) The reference to shrinking could relate to the now-known fact that Earth is compressed at the poles.

At a time when people generally believed that Earth was flat and stationary, the Qur’an explicitly and implicitly revealed that it is round. More unexpectedly still, it also says that its precise shape is more like an ostrich egg than a sphere: After than He shaped Earth like an egg, whence He caused to spring forth the water thereof, and the pasture thereof (79: 30-32).

The verb daha’ means “to shape like an egg,” and its derived noun da’hia is still used to mean “an egg.” As this may have appeared incorrect to pre-modern scientists, some interpreters misunderstood the word’s meaning as “stretched out,” perhaps fearing that its literal meaning would only confuse people. Modern scientific instruments recently established that Earth is shaped more like an egg than a perfect sphere, and that there is a slight flattening around the poles and a slight curving around the Equator.

The West receives “lost” knowledge

An enduring Western myth is that Columbus had to overcome a pervasive belief that he would sail off the edge of a flat Earth by sailing west to Asia. This myth stems in part from compressing the past and conflating the early Middle Ages, when Europe’s belief in a flat Earth was widespread, with the late Middle Ages, when Europe’s knowledge had caught up with and partially surpassed that of ancient Greece and medieval Islam.

During the Renaissance, Europe came into contact with “lost” knowledge by translating Greek and Arabic works. One important book was Ptolemy’s Geography, which accepts Earth’s spherical shape. Geography once more became available in the original Greek, which was not widely known in the thirteenth century. This book was translated into Latin in the late fifteenth century and became widely known. Columbus owned a copy printed in 1479.

By the time of Columbus, the idea of a spherical Earth was widely accepted in theory. Columbus believed this and wanted to sail west to the eastern shores of Asia. Earth’s size was the real issue. Ptolemy’s estimate was as much as 20% too low. Also, he vastly overestimated Asia’s size. The resulting map depicted an Earth with oceans between Europe’s western tip and Asia’s eastern tip, which was well within range of the provisions that ships of that time could carry. Columbus’ estimate of the distance to Asia was wrong, as was his assumption that there was no land between Europe and Asia. Fortunately for him, these two “wrongs” made a “right,” with all of its attendant fame and glory.

The Shape of the Universe

So far, we have given external information (i.e., lunar eclipses and the North Star) about Earth’s spherical shape based upon its position in the universe. If we use this method to determine the universe’s shape, we must observe it in an external manner. As this is not possible, let’s reconsider the question of Earth’s shape with a slight change: Can we determine Earth’s shape by using measurements and observations done only on its surface, and thereby acquire intrinsic information that can inform us of the universe’s shape?

Karl Gauss (1777-1855) answered this question positively by inventing “curvature,” which measures a given surface’s “bumpiness” at a specific point. A flat piece of paper has no bumps and so its curvature is zero. But if we look at a sphere at each point, we see some bumpiness. Gauss called such bumpiness “positive curvature.” Another kind of bumpiness is “saddle-shaped.” We can think of positive curvature at a point as follows: If we put a piece of flat paper on a surface at that point, the surface lies totally on one side of the paper. But in negatively curved space, this cannot happen.

To describe this concept formally (minus some technicalities), assume constant curvatures on the shapes in question. In other words, the shape is totally symmetric and every point has the same amount of bumpiness. There are several ways to describe curvature. Gauss’s formulation for curvature is brilliant. But before that, let’s look at his intrinsic proof for a spherical Earth. Imagine an orchard so large that any deviation from flatness is perceptible. First plant trees on the Equator every 100 kms (the approximate distance between two meridians on the Equator). Then plant another tree 100 kms (the approximate distance between two parallels) north of each tree, and do this several times. If Earth is flat, the distance between them would be same. But since the distance between the two consecutive trees (on the same parallel) decreases, Earth is spherical.

Having seen that an intuitively positive curvature implies a spherical shape, we want to follow this method to get an idea about the universe’s shape. Georg Riemann (1826-66), trying to do just that, invented “curved space” and explained how to compute its curvature. We could launch six probes at equally spaced points along the Equator, and have each of them continually monitor the distance to the two adjacent probes. If space is flat, the distances at any point in its journey would equal the distance from the probe to Earth’s center (an equilateral triangle). For negative curvature, the distance between probes would grow faster than the distance the probe had traveled from Earth; in positively curved space, the distance between probes would grow slower than the distance covered by the probes since leaving Earth.

There are two common misconceptions about the curvature of space. The first one is that curvature is a rather vague or qualitative concept. In reality, it is quite precise and assigns to each point in space and each direction at that point an exact number determined by the shape of the space near the specific location. The second one is that to describe curved space, one must think of it as “curving” into a fourth dimension. This can be useful in visualizing curved space for people familiar with four-dimensional Euclidean space (four-dimensional coordinate space). Unfortunately, science popularizers and science fiction writers often lace this concept with mystical overtones. This is more likely to confuse average people. In other words, measurements made in ordinary three-dimensional space may disagree with the results embodied in Euclidean geometry, for curvature measures the degree and kind of deviation from the Euclidean model.

Riemann also proposed a radically different (non-Euclidian) model for the universe: “spherical space.” This would be the case if space had a constant positive curvature. Based on this, he said that the universe should be a hypersphere (a three-dimensional sphere). The usual sphere is two-dimensional and lives in three-dimensional Euclidean space. In general, n-dimensional sphere is described as in the (n+1)-dimensional Euclidean space, and the set of points whose distance from origin (the point 0) is 1.

The more intuitive way to describe hypersphere comes from the usual sphere. Starting from a point in the sphere called the South Pole, and as we go in a direction in the sphere, we see concentric circles becoming larger until we reach the Equator, after which they become smaller and we finally reach North Pole. The situation is similar in hypersphere. Start from a point in the sphere called the South Pole, and as we go in a direction in the sphere, the concentric “spheres” become larger until we reach the Equator, after which they become smaller until we reach the North Pole. We can generalize this concept for any sphere of any dimension.

Earlier philosophers speculated that the universe was infinite in extent; others (e.g., Plato, Aristotle, Newton, and Leibniz) rejected this as implausible. But the alternative seemed equally dubious: If it did not go on forever, then “like the flat Earth” it had to end somewhere. And, what was beyond that? This model solved the Euclidean paradox of the universe’s “edge,” for if the universe is positively curved, it can be finite in extent and still not have any “edge.” In Riemann’s model, every part of the universe looks just like every other part, as far as shapes and measurements go.

Qur’an 51:47-48 mentions the universe’s spreading out or expansion in space: And the firmament: We constructed it with power and skill, and We are spreading it. This verse reveals that the distance between celestial bodies is increasing, which means that the universe is expanding.

Hubbel’s law

The most surprising discovery of the twentieth century was made by Edwin Hubble in 1929: The universe is not static, but is in a state of rapid expansion. Based upon his observations, he stated Hubble’s Law: Other galaxies are receding from us, the rate at which they recede depends upon their distance, and there is a constant ratio (the Hubble constant) between their velocity and their distance from us.

This law’s most dramatic consequence is what it tells about how we got to where we are now. If distances between galaxies increase as we look toward the future, they must decrease as we go back in time. Each ring of galaxies must have been closer to us in the past; the further away (or back in time) we go, the closer they would have been, and the faster they appear to be moving toward us.

Hubbel’s evidence was limited to a few relatively nearby galaxies. Over the years, however, thousands of observations extended and refined the measurements, and confirmed the general correctness of the velocity-distance relation. Current best estimates are that those galaxies are a billion light-years away (a light-year is roughly 6 trillion miles). Assuming that light always travels at the same speed, those galaxies must have been 1/20 of a light-year closer to us each year in the past. To have ended up a billion light years away, they must have started at exactly the same point as we did “the Big Bang” some 20 billion years ago.

Let’s start by using concentric rings of galaxies at intervals of a billion light-years. Then there are 20 rings, because five rings from us represents galaxies 5 billion light-years distant from us. To see them, we need to see their light that has been traveling for 5 billion years. Thus, we now see their position 5 billion years ago. As there was nothing 20 billion years ago, the outmost ring must the twentieth ring. This might sound paradoxical, as the circles of galaxies seem to grow larger as they move further away from us. However, the paradox is only apparent. Assuming Earth is in the South Pole and that the rings are a sphere’s latitudes, the rings become larger by the Equator and then become smaller until, in the twentieth ring, we reach the North Pole. This time, the rings are spheres and thus fit in the hypersphere. So Hubble’s Law supports our model of hypersphere for the universe.

But how can an expanding universe fit into our picture? In the sphere, the whole surface is expanding, just like inflating a balloon. So the distance from us (at Earth) to the Big Bang is increasing in all directions. In other words, any two points in the universe recede from each other, just as any two points on the balloon recede from each other during inflation.

The issue of time

So far, we have considered the universe’s shape at a fixed time. But, in physics, it is useful to consider space and time together. After Einstein’s brilliant publications about special relativity, Hermann Minkowski (1864-1909) proposed a very useful four-dimensional space-time model as the fabric of the physical universe. In a global picture, each fixed time represents a thin slice of space-time. Like an onion, each layer (assuming there are infinite very thin layers) corresponds to the universe at different fixed times. Given that each fixed time is a hypersphere, the layers are hyperspheres. According to Hubble’s Law, the hypersphere becomes larger as time passes. Just like an onion, the inner layers are smaller and the outer layers are larger.

In an ordinary onion, the layers are usually spheres; in the universe, the layers are hyperspheres. Assuming that the outer-most slice represents the universe at this time, the space-time “so far” is a four-dimensional onion, with layers of the universe at different times. The center of this “onion” corresponds to the Big Bang. We receive the picture of space-time until “this time.” Now, let mathematics predict the future of the space-time, just as Newton’s laws allowed a detailed description of the solar system’s future course. As time evolves, the universe expands, distances between galaxies grow, and gravity weakens. Thus, the space-time curvature diminishes and successive hyperspheres grow at a slower rate.

Two possibilities emerge: The hyperspheres continue to grow indefinitely, although at an ever-decreasing rate, or reach a maximum size and start to contract, in exactly the same fashion as the parallels of latitude on Earth: starting at the North Pole, growing until they reach their maximum size at the Equator, and then begin contracting toward the South Pole. If the universe contracts, distances between galaxies would decrease, gravity and curvature would increase, and the successive hyperspheres would shrink ever faster, eventually contracting into a single point: the “Big Crunch.”

We could then draw a map of the universe as a succession of hyperspheres growing in size for during the first half of its life and contracting during the second half. All space-time would then form a kind of super-hypersphere a four-dimensional object known as a “four-dimensional sphere.”

Conclusion

At a fixed time, the universe should be a hypersphere. When the time dimension is added, space-time should be super-hypersphere, with a “Big Bang” like the South Pole, each fixed time of the universe corresponding to the parallels, and finally a “Big Crunch” corresponding to the North Pole in our space-time model.

Almost everybody has heard that time is the fourth dimension. Even though this concept is easy to imagine, people find it hard to understand because of its mystification by science popularizers. We live in three-dimensional space. This means that I can parameterize the universe such that I can describe any point in it by using just three letters (a, b, c).

Footnotes

1. All of these statements are only approximately true. They would be exactly true if the North Star was precisely overhead at the North Pole, instead of being off center by about 1.
2. The real estimate might not be 25,000 miles, as we do not know the exact correspondence between ancient and current measurements. However, this was a very good estimate for that time.
3. Despite the potential errors mentioned in footnote 2, this also was a good estimate for that time.

Cosmology is the study of the universe’s beginning, formation, and evolution. Humanity has devised many cosmological theories. For example, ancient Greeks thought the universe was composed of four elements: earth, wind, fire, and water. Now, despite several millennia of effort, modern cosmologists are even worse off.

About 60 years ago, Fritz Zwicky realized that clusters of galaxies consist mainly of matter in some non-luminous form, defined as matter that we cannot see with our telescopes. Now, after decades of accumulated observations, most astronomers believe that as much as 90 percent of this material may consist of objects or particles that cannot be seen. That is, most of the matter in the universe does not radiate light. Previously, people called this phenomenon missing matter. Contemporary researchers prefer dark matter, for it is the light, not the matter, that is missing.

In this article, I discuss evidence that proves the existence of dark matter, possible candidates for dark matter, and the importance of dark matter in understanding the universe’s beginning and end according to the Big Bang theory.

Obsering the invisible

As dark matter emits no electromagnetic radiation (e.g., light, radio waves, and X-rays), it cannot be seen by a telescope. However, we can infer its existence through its gravitational effects on luminous matter. The most obvious example of this is observed when looking at the rotation rates of galaxies. Using the resulting information, scientists can calculate the speeds of stars as they rotate around a galaxy’s center (orbital speeds) in two different ways. The first way is to look at the light coming from stars in different parts of a galaxy. Through a close study of that light’s properties, they can deduce how fast and in what direction (whether toward or away from us) that star is rotating. The second way is based upon gravitational physics. Given that we know how much matter the galaxy contains, we can calculate how fast stars must be orbiting around its center. By accounting for all of the galaxy’s luminous matter (e.g., stars, gas, and dust), astronomers can calculate the star’s orbital speeds.

But there is a problem here: The two results do not agree. The only way to account for this difference is to posit the existence of a large quantity of dark matter in the galaxies. To explain the astronomical observations, this dark matter must surround the galaxy in a large spherical distribution (known as a galactic halo).

Is the gravity of the galaxies seen in this image strong enough to contain the glowing hot gas? Superposed on an optical picture of a group of galaxies is an image taken in X-ray light. The X-ray picture shows confined hot gas highlighted in false red color and provides clear evidence that the gravity exerted in groups and clusters of galaxies exceeds all of the individual component galaxies combined. The extra gravity is attributed to dark matter, the nature and abundance of which is one of the biggest mysteries in astrophysics today. Credit: Richard Mushotzky (*)

Another effect, known as gravitational lensing, gives evidence for dark matter’s existence. This effect occurs when a massive object’s gravity bends the light that is passing by. For instance, when a cluster of galaxies blocks our view of another galaxy behind it, the cluster’s gravity warps the more distant galaxy’s light into rings or arcs, depending on the geometry involved. By observing these rings, one can calculate how much mass should be present inside the galaxy to produce this pattern. Such calculations confirm that clusters contain far more mass than the luminous matter suggests.

Image of the rich galaxy cluster Abell 2218, taken with the Hubble Space Telescope. This cluster shows evidence of multiple lensing images, as well as numerous strong and weak arcs. Using information about the arcs and multiple images allows astronomers to reconstruct the mass distribution, which then gives us knowledge about the distribution of dark matter. (*)

Dark matter defined

Understanding dark matter is a key to other important issues in cosmology, such as how much mass the universe contains, how galaxies formed, and whether or not the universe will expand forever.

The posited explanations for dark matter can be grouped into three main categories:

– Dark matter could be some kind of ordinary matter that emits or reflects too little radiation for our instruments to detect. Such objects are known as massive astrophysical compact halo objects (MACHOs) and may be ultrafaint stars, large or small black holes, cold gas, or dust scattered around the universe.

– Dark matter could consist of exotic, unfamiliar particles (i.e., different from such known particles as electrons, protons, and neutrons) that we have not figured out how to observe. These are known as weakly interacting massive particles (WIMPS). Despite the many theories about them, their existence remains unconfirmed. These exotic particles are thought to have very small masses (smaller than atoms), meaning that there would have to be a huge number of them to make up the missing matter. Thus, millions of WIMPs are passing through Earth and us. They interact with ordinary matter only by means of gravity. Since the interaction is very weak, it is difficult to detect them.

Our understanding of gravity needs a major revision–but most physicists do not consider this option seriously.

Dark matter and the universe

The search for dark matter is more than trying to explain discrepancies in galactic mass calculations, for it is closely related to how the universe was formed and will end.

The Big Bang theory, which tries to explain how the universe was formed, maintains that in the beginning, everything was compressed into a single point. Then, a great explosion resulted in the universe being formed. It is still expanding. This theory is based on the fact that all galaxies, when observed with telescopes, are moving away from each other. After this explosion, matter started clumping together to form the stars and galaxies we see today.

The picture shows mankind’s deepest, most detailed visible view of the universe provided by Hubble telescope. Representing a narrow keyhole view stretching to the visible horizon of the universe, the Hubble Deep Field image covers a speck of the sky only about the width of a dime 75 feet away. Though the field is a very small sample of the, it is considered representative of the typical distribution of galaxies in space, because the universe, statistically, looks largely the same in all directions. In this picture, Hubble uncovered a bewildering assortment of at least 1,500 galaxies at various stages of evolution. (*)

One problem with this theory is explaining how the stars and galaxies were formed. If matter initially was distributed evenly in all directions, what caused it to clump together in some regions and form stars and galaxies? Gravity alone cannot cause this in a smooth universe, and so something had to supply the initial gravity that allowed galaxies to form. Physicists suggest that dark matter WIMPs accomplished this task. Since WIMPs only affect ordinary matter gravitationally, physicists say this dark matter could be the seed of galactic formation.

According to the Big Bang theory, there are three possibilities for the universe’s future. In a closed universe, gravity is strong enough to stop the expansion eventually and pull everything back to a single point. In an open universe, gravity cannot stop the expansion and so it will continue forever. In a flat universe, there is just the right amount of mass so that gravity can stop the expansion but not pull it back into one point.

The amount of dark matter that exists is crucial to determining the universe’s fate, because the Big Bang theory posits that the amount of mass in the universe determines gravity’s strength and, by extension, whether the universe will be closed, open, or flat. To quantify this, scientists define a constant, called Omega, as the ratio of the universe’s density to some critical density. A flat universe is said to have an Omega of 1, meaning that its density is equal to that of the critical density. If the density is greater than 1, the universe is closed; if it is less than 1, is be open. Without dark matter, the universe’s observed density is between 0.01 and 0.1. Therefore we live in an open universe. If a lot of dark matter were present, the universe would be closed. If there were just the right amount present, it would be flat.

Conclusion

The discovery of dark matter could affect our view of our place in the universe. If its existence were proven, our world and its inhabitants would be made of something comprising an insignificant portion of the physical universe. This probably would not affect our daily life, but would create a new scientific paradigm. In this sense, the discovery of dark matter would be as revolutionary as finding of extraterrestrial life.

Footnotes

1. Herman, R. and S. L. Larson. Is Dark Matter Theory or Fact? Scientific American (15 June 1998).
2. Rubin, V. Dark Matter in the Universe. Scientific American (March 1998).

* http://www.nasa.gov

Cosmology is the study of how the universe we live in came into being, why it looks and behaves as it does, and what its ultimate fate is. Building on the work of Albert Einstein, cosmologists have come up with a new account of the origin of the universe, the so-called big-bang cosmology. Over the past three decades a series of observational developments and refinements to the theory have led to its wider acceptance. For the present, there are no fundamental challenges to the big bang theory, although there are certainly unresolved issues with the theory itself. Astronomers are not sure, for example, how the galaxies were formed, but it is questionable whether there is a reason not to think the process did not occur within the framework of the big bang. Indeed, the predictions of the theory have survived all tests to date.

Nevertheless, we should always bear in mind that present-day science is not the last word, and perhaps Einstein’s theories, and the big-bang cosmology, will in turn be superseded.

Our present knowledge of the universe is restricted to a handful of observational facts. The expansion of the universe, indicated by the law relating the red shift in light from astronomical objects to their distance, was dis¬covered by Edwin Hubble in the early part of this century. The existence of the microwave background radiation corresponding to a temperature of 2.7K, and the cosmological abundance of helium are more recent discoveries. Together, these three observations suggest that the universe was born in a hot fireball from a very dense state-the big bang. Not just matter was created in the big bang, but space-time as well. There was nothing outside for the big bang to explode into-and this nothing means not even empty space.

Cosmologists today do not claim to know exactly what made the universe explode into existence from a state of zero volume and infinite density-a space-time singularity-but they do claim to be able to describe in great detail how a hot fireball of matter and radiation has evolved from a fraction of a second after the instant of creation over about 15 billion years to produce the cool, dark spread of empty space, dotted with galaxies made up of stars, gas, dust and planets, that we see about us now.

The laws of nature as we currently understand them allow us to trace the observed expansion of the universe back billions of years to what would be a true beginning, a moment when the universe was infinitely hot and dense. Although, theorists are now pushing back their speculations about what happened in the first 10-35 seconds after the big bang, with less confidence, the modern cosmological world view begins at a time when the universe had cooled to only 1012K, about 10-5 seconds after the instant creation. At these extreme conditions, the laws of physics as deduced here on earth can be applied to produce the story of everything that ha happened since. At a temperature of 1012K, particles and radiation would be interchangeable, as the mass equivalent of energy in the radiation would be ample to produce particles like protons, neutrons, and electrons, not out of thin air but out of thick radiation, in line with the rules E=mc2 for a particle of mass m and E=hv for radiation with frequency v (h is Planck’s constant). Here higher black body temperature of radiation corresponds to bigger v, that is bigger energy E, and therefore to more massive particle equivalents.

So, one-hundred-thousandth of a second after it began, the universe would have been a seething mass of particles and radiation, a swirling soup in which particle/antiparticle pairs were constantly being created out of energetic photons, and constantly annihilating with one another to produce other energetic photons. Overall though, the total mass/energy of the whole system was constant. For every E/c2 of mass created or destroyed an exactly equivalent E/h of radiation is destroyed or created.

Things began to get more orderly at 1011, still within the first 0.1 seconds after the big bang, as the universe expanded so that the density of radiation at any point was no longer enough to produce the more exotic particles. Only electron/positron pairs, and the massless photons and neutrino/antineutrino pairs, were light enough to have a continuing involvement in the matter/radiation balance.

About 14 seconds after the big bang, the temperature of the universe had dropped to around 3xl09K, and even electrons and positrons needed too much energy for the weakening radiation to create them. As the universe con¬tinued to expand and cool, creation became slower than annihilation, and almost all the particles and antiparticles disappeared. But for some unknown reason, a small proportion of electrons, protons and neutrons were left over. It is this early excess of matter over an¬timatter that survived to form light atomic nuclei a few minutes later, then (after about a million years) to form atoms and, still later, to be cooked to heavier elements in stars, ultimately to provide the material out of which life would arise. The reason for this predominance of matter over antimatter remains a mystery and has been a source of concern to modern cosmology. It is, nevertheless, one of the key initial conditions that determined the future development of the universe.

As the temperature dropped to 109K-about 70 times the temperature in the heart of the sun today-many protons and neutrons fused into helium nuclei, and by the end of first four minutes no free neutrons were left. Some 75% of the mass of the visible universe had been processed into protons plus electrons (ultimately to be bound into hydrogen atoms) while rather more than 25% mass of the universe had been processed into helium. The abundance of these elements in the universe is detectable today, and provides a constraint on the range of allowable models.

Another 700,000 years later, the expanding universe cooled to the point where electrons can bind to helium and hydrogen nuclei to make atoms, at a temperature of around 5000K. This signalled the end of the last remaining links between matter and radiation on a cosmic scale. Although free electrons and atomic nuclei, being electrically charged, interact strongly with radiation, electrically neutral atoms do not. From then on, the background radiation had nothing left to do but spread thinner in the expanding and cooling universe, to become the faint hiss we now detect at temperature equivalent of 2.7K. The very high degree of uniformity of the microwave background today is a strong indication that uniform, isotropic models provide a good description of the universe.

After the first thousand million years or so, with matter firmly established and radiation playing only a minor and decreasing role, the story of the universe can be taken up in terms of gravity, left as the dominating force because of its long range and its independence of electric charge. Gravitational forces then shaped the galaxies by holding stars and planets together.

However, our grasp of the conditions that prevailed in the early universe does not translate into a full understanding of how galaxies formed. Many scientists believe that the hydrogen and helium gases that filled the universe must have been pulled into concentrations by gravity. But there are problems with this explanation: for, what could cause large, diffuse gas clouds to collapse, even with the aid of gravity, while the universe as a whole is expanding?

Having established that the universe began in a hot big bang, and being tolerably happy with a rough understanding of how galaxies formed, the truly cosmological question remaining for astronomers to puzzle over is whether the universe is open (will it expand forever) or closed (will it one day collapse into a new fireball)?

The answer lies in its density. The symbol used for the mass density of the universe is Omega. If Omega, is less than 1, the universe will expand forever, so that, eventually, all the galaxies and stars will grow dark and cold. The alternative to this ‘big chill’ is a ‘big crunch.’ If Omega is more than 1, gravity will eventually reverse the expansion, and all matter and energy will be reunited. For the present, since we are not sure how galaxies formed, the value of Omega is uncertain-most astronomers put it somewhere between 0.1 and 1.

While eternal expansion is the generally favoured hypothesis; there may be enough of the unseen matter in the universe to produce a gravitational pull capable of halting the expansion and eventually producing a recollapse. Though the case is not yet proven, one current idea is that neutrinos, once believed to be massless particles, may have a rest mass less than 1/10000 of an electron. As neutrinos are thought to be as numerous as photons, their aggregate mass could suffice to close the universe. The fact that we cannot see enough matter to close the universe does not mean that it is not there.

During the next decade, as techniques for measuring the mass of the universe improve, we may learn whether the present expansion is headed toward a big chill or a big crunch. What happens then? Just as we do not know how everything could appear from nothing in the big bang if space-time did not exist, we do not know what happens to the universe at this stage; the laws of physics are inadequate to describe such extreme conditions. If there is ever to be a solution to the mystery of the origin and end of the universe, it must await a substantial increase in our understanding of the quantum nature of gravity-the big bang account of creation has forged an unlikely marriage between cosmology, the science of the very large, and particle physics, the science of the very small.

In any event, the universe we inhabit seems to be very improbable. Random processes and statistical fluctuations on cosmological time scales could easily have made it quite inhospitable to life. Are we just lucky? Or is there some deep significance to the fact that we live in a universe just right for us?

For all its violence-including the possibility of a black hole resident at the centre of our own galaxy-the universe seems to be an ideal place for man. Everywhere we look in the universe, from far flung galaxies to the deepest recesses of the atom, we encounter order. The laws of physics can explain beautifully the analytic structure of nature, the behaviour of individual particles and fields, but tell us nothing about the collective, collaborative organization of matter: that is, how the world is put together.

Why is the world the way it is and not otherwise? This is not the type of question scientists normally ask. The customary approach to scientific inquiry is to discuss what we see, not what we might see. Nevertheless, the universe is such a remarkable place, and we, as observers, are perhaps the most remarkable feature, it seems worth while ascertaining just how probable or improbable the present arrangement is.

For example, we do not understand why the fundamental constants of nature have the values they do. Einstein captured its essence when he said: ‘What really interests me is whether God had any choice in the creation of the world.’ Very slight changes in the physical constants of nature could have made the universe unfold in a completely different manner.

Most of the features of the everyday world and the astronomical scene are determined by a few basic physical laws and constants, such as the masses of the elementary particles and the relative strengths of the basic forces that operate between them. In many cases, a rather delicate balance seems to prevail. For example, if the nuclear forces were slightly stronger then they actually are, compared with electromagnetism, the di-proton-an atomic nucleus containing just two protons and no other particle-would be stable; ordinary hydrogen would not exist, and stars would evolve very differently. If nuclear forces were slightly weaker, no chemical elements other than hydrogen would be stable, and chemistry would be dull indeed. In either case, we would not be here to ponder such matters.

Or suppose the constant of gravity were stronger and the gravitational force were, say 1030 times weaker than the electromagnetic force instead of a factor of 1040 weaker. Then we would have a small-scale, speeded-up universe, in which stars-gravitationally bound fusion redactors-had only 10-15 times the sun’s mass, and lived for about a year. This might not allow time for complex systems-such as life forms-to evolve. The question-Was the relative strength of electromagnetic force over the gravitational force there from the beginning of time or is it an accident of today? -remains intractable.

These mysteries are heightened when we reflect how surprising it is that the laws of nature and the initial conditions of the universe should allow for the existence of beings who could observe it. Life as we know it would be impossible if any of several physical quantities had slightly different values. The best known of these quantities is the energy of one of the excited states of the carbon-12 nucleus. There is an essential step in the chain of nuclear reactions that build up heavy elements in stars. In this step, two helium nuclei join together to form the unstable nucleus of beryllium-8, which sometimes before fissioning absorbs another helium nucleus, forming carbon-12 in this excited state. The carbon-12 nucleus then emits a photon and decays into the stable state of lowest energy. In subsequent nuclear reactions carbon is built up into oxygen and nitrogen and the other heavy elements necessary for life. If the energy of the excited state of carbon-12 were just a little higher, the rate of its formation would be much less, so that almost all the beryllium-8 nuclei would fission into helium nuclei before carbon could be formed. The universe would then consist almost entirely of hydrogen and helium, without the ingredients for life.

Moreover, if the proton and neutron masses were equal, then neutrons and protons could not bind to form deuterium and heavy nuclei, and nuclear burning in stars and, consequently, life would be impossible.

The most ubiquitous examples of orderliness in the universe are the stars. They represent an extreme departure from thermodynamic equilibrium because they burn brightly in a cold, dark space. The source of starlight is the nuclear furnace at the core of the star, where the chief nuclear reaction is the fusion of hydrogen to helium. This is a downhill process, leading to nuclei of greater stability, and the cost paid for achieving it is the redistribution of nuclear energy into the surrounding space in the form of heat and light. This particular orderliness, and with it most familiar examples of terrestrial organization, leads to the question: Is the present structure of the universe-which is made mainly of hydrogen and not helium or heavier elements-just luck, a coincidence? Because, if the universe were made of, say, iron (the most stable element) there would be no stars like the sun.

Also, the structure of our world depends vitally not only on the availability of free hydrogen, but also on the reasonably smooth distribution of the primeval matter. If the big bang had only coughed out black holes-the ultimate triumph of gravity-in which everything is completely obliterated and disappears, no life would have been possible.

Can all these peculiar ‘coincidences’ be understood in terms of some self-evolutionary mechanism?

In its standard form, the big bang theory assumes that all parts of the universe began expanding simultaneously. Observations confirmed this assumption and showed that the expansion is remarkably uniform in all directions. This would seem to imply a collaboration between widely separated regions of the cosmos to expand at the same rate everywhere. Such highly organized behaviour leads us to ask how all the different parts of the universe could synchronize the beginning of their expansion?

Where does the energy that makes the universe expand come from? What could be a permanent, decidedly nonzero source of energy in the universe, with cosmic consequences? Could it be vacuum-as the source of everything yet itself nothing? This is one of the hottest topics in contemporary physics and lies at the heart of perhaps the most important new concept in cosmology of the past decade. If it is correct, could the creation of being out of nothingness occur without the mediation of a Creator?

There are many such peculiar ‘coincidences’ in the universe. Is it just our luck that they have worked out that way, or is there a deeper explanation? One understanding would be that the world is the way it is because it is the creation of a Creator who wills it to be capable of fruitful process: His command, when He desires a thing, is to say to it ‘Be!’, and it is (Ya Sin, 36.82). Without an Organizer, chaos can never be transformed into cosmos. This explanation is not a temporary sop to satisfy our curiosity about phenomena for which we cannot yet work out a satisfactory physical explanation; rather, it is a step guiding us towards a better understanding of the real world.

That does not mean that these mysteries constitute a barrier beyond which science cannot pass. As in the past, we may reasonably expect that, in the future, deeper understanding will be achieved and a more profound pattern discerned at the basis of physical reality, in a new, perhaps new kind, of explanatory theory. It may be some version of supergravity or it may be the novel theory of ‘superstrings’. Or some other theory that we have not yet thought of.

However, we should bear in mind that both our growing knowledge about the universe, and the need, alongside it, to revise it continually, is clear evidence for the inconclusiveness of science and the limitation of its methods.

In addition, the finititude of man’s existence (in this very small part of a vast universe) and the limitations of his senses mean that all our efforts must be considered ‘relative.’ The results of pure and experimental sciences are a limited portion of reality as man can grasp it from his location in the universe and within the very limited time allotted to him, and not the truth itself. There is of course, a great difference between being aware of things and knowing their actual truth. The former is limited to sensible events only, while the latter lies beyond the capacity of our senses.

No inquiry into the nature of creation or any part of it can be closed and concluded. The patterns of God in creation are infinite: there will always be more of them to discover. As we strive to do so, understand more and more about nature, the scientist’s sense of wonder will not diminish but become sharper, more narrowly focused on the mysteries that still remain. The worth of science lies in its commitment to understanding the Divine handiwork. The comprehensibility of the reality around us is among the greatest of God’s favours to us. Einstein remarked this: ‘The most incomprehensible thing about the universe is that it is comprehensible.’

The Qur’an contains many scientifically accurate statements, some of them still relevant to cosmology; it does not contain any statements which are in conflict with the findings of man’s scientific research nor open to criticism from modern science. Many of its verses allude to, and urge, reflection upon the reality around us as a form of worship, as a way to draw nearer to the Creator. I shall conclude by citing (in translation) a verse which draws our attention to the fact that, in a general sense, the future will be the age of knowledge and information, and that as a natural consequence of this, it will be an age of faith and belief:

Soon We shall show them Our signs on the furthest horizons, and in their own souls, until it becomes manifest to them that this is truth. Is it not enough that your Lord witnesses all things? (Fussilat, 41.53)

USEFUL READING

• GRIBBIN, J. (1982) Cosmology today: A New Scientist Guide
• JAMES, P. et al. (1994) ‘The Evolution of the Universe’, Scientific American, October
• SIMSEK, U. (1986) Big Bang-Kainatin Dogusu, Yeni Asya, Istanbul
• NURBAKI, H. (1989) Verses from the Glorious Qur’an and the Facts of Science, Turkish Foundation for Religion Publications