A new Artificial Intelligence (AI) approach to translate brain waves into speech

Akbari et al. Towards reconstructing intelligible speech from the human auditory cortex. Scientific Reports January, 2019.

In a recent study, researchers demonstrated that brain signals from the human auditory cortex can be reconstructed into intelligible speech with a high rate of success. In the study, the brain signals from the auditory cortexes of five participants (suffering from epilepsy) were recorded while they were listening to stories and numbers being read. Researchers specifically chose epilepsy patients as they were already undergoing a clinical procedure involving the placement of electrodes into the temporal lobe of their brains. This procedure is called invasive electrocorticography. The researchers then spoke 10 numbers into the ears of the test subjects: zero to nine. Each number produced a unique response in the brain. The sound produced by the vocoder in response to those brain signals was analyzed and cleaned up by neural networks, a type of artificial intelligence that mimics the structure of neurons in the biological brain. Remarkably, the robotic translations were successfully understood by 75% of people enlisted to test the technology. These results suggest a hopeful future for the Brain-Computer Interface. In particular, this new technology has great potential at giving a voice to people who are paralyzed or severely injured. Despite the potential, the path for a practical device is still long. To go beyond simple numbers and access the thoughts that go with speaking, the researchers will have to probe a different part of the brain known as the Broca area. It is found in the frontal lobe and linked to speech production and language processing.

Milky Way is warped and twisted, not flat

Chen, et al. An intuitive 3D map of the Galactic warp’s precession traced by classical Cepheids. Nature Astronomy February, 2019.

Astronomers have been studying the Earth’s home galaxy, the Milky Way, for centuries in efforts to get a better understanding of its size, structure, and place in the universe. While modern instruments have provided invaluable details about our galaxy and others, a truly accurate model of our galaxy has been missing. Researchers have recently built, for the first time, an accurate 3D map of the Milky Way. We often think of spiral galaxies as a flat thin disk of stars that orbit around a central region, where billions of stars provide the massive gravitational force to hold everything together. However, a new study showed that the Milky Way’s gas disk is no longer confined to a thin plane, but is instead organized in an S-like, warped appearance. The researchers determined the Milky Way’s exact shape at high accuracy by measuring the distances to so-called Cepheid variable stars. Cepheids are young stars that can be up to 20 times as massive and 100,000 times as bright as our Sun. These high stellar masses live fast and die young, sometimes after only a few million years. They also show day-to month-long pulsations, which are observed as changes in their brightness. Combined with a Cepheid’s observed brightness, its pulsation period can be used to obtain highly reliable distances.  By using the data of 1,339 Cepheid stars as benchmarks, researchers were able to map out accurate distances between objects in the Milky Way. Interestingly, in the Milky Way’s outer regions, they found that the S-like stellar disk is warped in a progressively twisted spiral pattern. Researchers suggested that the Milky Way’s warped spiral pattern is most likely caused as a result of rotational forcing or “torques” by the massive inner disk. The further stars are from the center of the galaxy, the weaker their gravitational pull is. This new morphology is expected to provide a crucial updated map of our galaxy’s stellar motions and the origins of the Milky Way’s galaxy.

Smart fabric self-cools or self-insulates depending on conditions

Zhang et al. Dynamic gating of infrared radiation in a textile. Science, February 2019

Decades of innovation in fabrics have yielded high-tech materials that react to hot and cold conditions, allowing them to keep marathon runners cool or alpine hikers warm. However, there was never a material that could change the insulating properties of fabric in response to the environment. A recently developed fabric is the first to automatically warm wearers up or cool them down as needed. Infrared radiation is the primary way the body releases heat and is the focus of this new technology. When the condition is warm or moist, like when a body sweats, the fabric allows the infrared radiations to pass through. Conversely, in cool and dry conditions, the fabric traps the surrounding heat that escapes. The fibers are made of two different synthetic materials coated in carbon nanotubes – one absorbs water, and the other repels it. When the material gets hot and wet during sweating, the strands twist and warp. This distortion brings the strands of yarn closer together, which opens the pores in the fabric to allow heat to escape. When a wearer is too cool, this mechanism is blocked, trapping heat close to the skin. The reaction takes place almost instantly. The garment cools people down before they realize that they are getting hot. Athletes perhaps will be the first people to wear clothes made from the material, but it could be useful for infants, people with disabilities, and the elderly. Researchers say it could be in production within months as the base material is easily available and the carbon coating can be effortlessly added during the standard dying process.

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).

Can an apple move the earth? Physics says it can. The power that gave an apple the ability to move the world, also gave us humans the capacity to make use of the natural laws and be a true vicegerent on the earth.

In a universal arrangement of objects, from the smallest to the largest, in terms of length, time, and mass, where is the human located? In between the diameter of an atomic nucleus (10-14 meters) and the distance of the farthest galaxy from the earth (1026 meters), the human being occupies a zone between one and three meters. The human lifetime can be measured to be around 109 seconds in temporal length, to the duration of a ray of light passing through a proton (10-24 seconds), to the age of the universe (1017 seconds). And the human mass is located around a 102 kg zone, on a scale from the mass of an electron (10-31 kg), to the mass of the Milky Way galaxy (1041 kg).

Based on this data, understanding the human that is trapped in this enormous universe is crucial. Humans are just a speck, jammed between mote and sphere, living in a frail state of weakness and poverty. “Do not strut about the earth in haughty self-conceit; for you can never split the earth (no matter how hard you stamp your foot), nor can you stretch to the mountains in height (no matter how strenuously you seek to impress)” (Qur’an 17:37).

Humans, who need a vast amount of grace and support, are in search of answers to improve themselves. “Who am I?” they often ask; “where am I?” As scientists and researchers discover the excellence of the universe’s artistry, we begin to comprehend just how blessed humans are. Within the laws of science lie the answers to our questions. Laws are relative principles that operate according to the constants wisely built into the universe. These laws are veils to the majesty of creation. Each law is created anew every moment, thus we perceive them as if they are eternal patterns. For example, the human body gravitates to the center of the earth with a force equivalent to their mass multiplied by the average gravitational velocity of the earth, which is 9.8 m/s2. The law of gravity is created every moment in such fine measures that it is possible for us to walk on the ground.

It helps to remember Newton’s three laws in physics. The first is the principle of inertia, which states that unless there is an external force, or if the sum of all forces cancel each other out in direction and size, then an object is either at rest or moves at a constant velocity. The second law is that force equals the mass of an object multiplied with its acceleration. And the third is the action-reaction principle, which states that when a force is applied to an object, the object exerts a force in opposite direction, equal in magnitude. This means that when an apple is thrown into the air, and the apple accelerates in opposition to gravity, the earth is distanced from the apple with the same amount of force. Similarly, when the apple falls down because of gravity, the apple is also pulling the earth with the same magnitude. If this was to repeat constantly, theoretically a movement like the one made by a yo-yo should have happened between the apple and the earth. Because of its huge mass, the earth’s acceleration is very small, thus this yo-yo movement would not be felt. An object as small as an apple actually moves an object the size of the planet. This means that the power that gave an apple the ability to move the world, also gave us humans the capacity to make use of the natural laws and be a true vicegerent on the earth.

Nothing in the universe has been created in vain – all phenomena occur because of a purpose they are assigned to fulfill. In a universe in which everything is bound by a complicated web of laws that are created without a moment’s lapse, humankind surely has a significant role to play in the unique position with which they are graced. This position undoubtedly requires a sense of humility in the face of all the grandeur around us, yet also being aware of our given capacities, which enable us to master over all existence.

Finkelstein S.L et al., Nature, October 2013

Astronomers have recently spotted a faint ray of light using the Hubble Space Telescope, a ten-meter telescope at Keck Observatory, located at the summit of Mauna Kea, a dormant volcano in Hawaii. Analysis of light showed that it was a galaxy formed 13.1 billion years ago, which is only 700 million years after the Big Bang, when our universe came into existence. This is so far back in time, it would be about 8 billion years before our sun was born. The new galaxy is called z8_GND_5296, and it is the oldest and most distant galaxy ever discovered. Because the universe is expanding, the lights coming from distant objects would be stretched, and their wavelengths changed, as they travel through the expanding universe. This phenomenon is called Redshift. It makes visible light look redder, and redshift increases proportionally with the distance to an object. Lights coming from z8_GND_5296 looked more redshifted than anyone had seen before. More detailed analyses showed that the mass of gz8_GND_5296’s stars was equivalent to 1 billion suns, which is approximately 50 times less than the Milky Way’s stellar mass. Even more surprisingly, the new galaxy is found to have an unusually high star-formation rate. This rate is typically calculated by how much raw hydrogen the galaxy yearly converts into new stars. gz8_GND_5296 converts hydrogen 300 times the mass of our sun, while the Milky Way produces 1 or 2 solar masses per year. One of the explanations for this extraordinary star-formation rate is that the early galaxies contained or drew in much more gas than scientists expected. The search for distant galaxies aims to find the very first galaxies formed after the Big Bang, perhaps the ones that produced the first natural elements. To this end, NASA plans to launch the James Webb Space Telescope (JWST) in 2018. JWST will reside in an orbit 1.5 million km from the earth and hopefully it will help astronomers to look further and further back into the origins of the Milky Way, and ultimately, the history of our universe.

Vast Freshwater Reserves Found Under Ocean

Offshore fresh groundwater reserves as a global phenomenon.
Post V.E.A et al., Nature, December 2013

As earth’s population rises, we face a serious problem of fresh water supplies. The United Nations predicts that half of the world will be struggling to find clean, fresh sources of water by 2030. Luckily, Australian scientists discovered huge freshwater reserves, and in the most unexpected place: under the ocean floor. Newly discovered reserves are estimated to contain 500,000 cubic kilometers of low-salinity water, located off the coast of South Africa, North America, Australia, and China. This vast reserve is approximately 100 times greater than the volume of the fresh water used since the beginning of the 1900s. This water reserve is thought to develop earlier in Earth’s history, perhaps over thousands of years, when oceans were not that deep and when the coastline was further out. Scientists hypothesize that rainwater leaked through the ground and had created these fresh water aquifers beneath layers of porous rock and/or soil. Around 20,000 years ago, the polar ice caps began to melt and these regions were covered by ocean. Fortunately, layers of either clay or sediment seemed to protect the reservoirs from salty contamination: the salinity of this water is low enough to be readily transformed into drinkable water. These water reserves can be extracted by constructing drilling platforms, either at sea or from the mainland, close to aquifers. However, drilling projects are usually very controversial due to environmental and economic costs. Scientists are currently seeking alternative, more environment-friendly ways to use these reserves. Nonetheless, mankind may have found a new vital water resource for the future.

Crows Don’t Forget a Face; Crow Intelligence Decoded

Abstract rule neurons in the endbrain support intelligent behavior in corvid songbirds.
Veit L. and Nieder A., Nature Communications November 2013

Scientists have long suspected that members of the corvids – a family of birds that includes ravens, crows and magpies – are extraordinarily intelligent. They make and use tools, remember multiple feeding locations, and exhibit highly social behaviors. Last year, scientists even demonstrated that crows captured in Seattle would never forget the face of their abductor and they would still taunt and dive-bomb the threatening face several years after the incident. To understand the mechanism of crows’ amazing face recognition process, neurobiologists designed an experiment, in which they trained the crows to perform memory tests on a computer. The crows were first shown an image and shortly afterwards, they had to select one of two test images on a touchscreen, using their beaks, based on switching behavioral rules. One of the test images was identical to the first image; the other one was a different image. Sometimes, the rule of the game was to select the very same image, and sometimes it was to select a different one. Remarkably, the crows were able to carry out both tasks and to switch between them almost perfectly. These tasks require a high level of concentration and mental flexibility that few animal species can manage – they even require a great effort for humans. By recording single-unit neuronal activity from an association area of the crow’s brain, known as the nidopallium caudolaterale (NCL), the researchers were often able to guess which rule the crow was following, even before the crow made its choice. The cerebral cortex in human brain is very large and it is thought to be home to complex cognitive functions including face recognition. However, since a bird’s cerebral cortex is much smaller than humans, people long thought that birds could not perform intelligent tasks. This study shows that birds use a unique non-cortical brain region, nidopallium caudolaterale (NCL), to sort sensory information and decide how to react.

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.

If the universe was expanding, then it had to be smaller in the past, and there could even be a moment when the entire universe appeared as a tiny mass. A group of physicists who took these findings seriously, started theoretical research regarding the birth of the universe (that is, the space-time and all of the matter within) and its evolution. Another group of physicists still thought that the universe should have no beginning and insisted in their conception of a static universe. One of these physicists, Hoyle, made a statement during a BBC radio program in order to criticize the idea of an expanding universe and used the phrase “big bang” for the first time. Later on, the phrase, initially used in a sarcastic manner, started to be used as the name of the expanding universe model. It was an entirely new model no scientist had even imagined before. Accordingly, there had to be an electromagnetic radiation (cosmic microwave background radiation) which would emerge after the explosion—this can be compared to the smoke of a gun right after a fired shot. After Penzias and Wilson observed this electro-magnetic radiation in 1964, the doubts about the model disappeared almost completely. As technology developed over time, so many different observations and sensitive measures were made and taken in support of this theory. Since there is no other cosmological model to explain the present data, the Big Bang model has general acceptance among physicists today. We would like to relate some facts about the universe based on contemporary observations and theories before we expand our discussion.

What we know about the Universe

Galaxies are typical formations throughout the universe. The Milky Way galaxy, which hosts our solar system, is a disc-shaped one. The measurements revealed that the diameter of this “disc” is 100,000 light years and its thickness is 1000 light years (one light year is approximately ten trillion kilometers). There are approximately 100 billion other stars in the Milky Way galaxy similar to our sun. Owing to gravitational attraction, the number density of the stars near the center of the galaxy is higher—for the same reason, black holes are thought to exist in the centers of galaxies. The stars visible to the naked eye at night are the ones within the Milky Way galaxy. When further distances are observed through telescopes, other galaxies begin coming to sight as bright spots. Galaxies form galaxy clusters and the clusters form super-galaxy clusters. Even light year appears to be an unimportant unit of measurement in order to express these dazzling great distances. The most successful model we know that describes the universe is Einstein’s theory of relativity. According to this theory, space-time is a dynamic object and it can be curved. As for the force we feel as gravity, it is an outcome of the curved nature of space-time. The Big Bang model appears naturally within the general Theory of Relativity. The essential data we are going to relate here about the universe is mostly based on observations and general theory of relativity.

According to the Big Bang model, the universe was born in a very hot and dense form nearly 13.7 billion years ago. Here, we need to remember that the concepts of “time” and “space” as we know them came to being with the Big Bang. Therefore, asking what was there before the Big Bang is meaningless for this model. Similarly, the common notion of expansion brings to mind something expanding inside something else. However, it is possible to describe the universe without any notions of inside or outside expansion. That is, we do not have to assume another environment inside which the universe expands.

One of the important suggestions of the Big Bang Model is the fact that the universe was at a state of thermal equilibrium in the past. There is important data based on observation in support of this suggestion. Therefore, even though the term Big Bang brings to mind a chaotic happening, there was a very important state of equilibrium at the emergence of the universe. So many physicists have underlined the fact that this state of equilibrium is impossible to happen on its own. Our universe was born out of a very hot and dense state of equilibrium and it began to cool down as it expanded. The heat in the early periods was so high that matter was found in a plasma state formed by the smallest constituents of matter. As the heat decreased, the plasma also changed structure and different cosmic phases took place. For instance, when the heat dropped down to 1010 C atomic nuclei began to form out of neutrons and protons. When it dropped to 3000 C, atoms were formed. There are many observations in support of these different phases. For example, the electro-magnetic background radiation observed by Penzias and Wilson in 1964 is formed out of photons (i.e. light) released after the phase in which the first atoms are formed. The Big Bang model has so many more important details and the calculations made according to this model have been in conformity with observations. Together with that, it should be noted that as the known physics get closer to the moment of the bang (zero time), it loses validity and new theories are needed.

The expansion of the universe in the Qur’an

The Qur’an openly refers to the expansion of the universe. The 47th verse of the 51 chapter (Dhariyat) is translated as follows:

And the heaven, We have constructed it mightily; and it is surely We Who have vast power, and keep expanding it. (51:47)

The original Arabic phrase used, which refers to expansion, is “musiun.” The interesting point is that the sentence is a noun clause which denotes in Arabic grammar a quality of being steady and continuous. Therefore, the meaning can be understood as being “we are expanding it continuously.” According to the Big Bang model, the universe has constantly been expanding ever since it was born. Expressing this fact by saying “We are expanding it,” the Qur’an also guides us to acknowledge that the expanding does not happen in itself but is realized by Divine power.

Other verses related to the Big Bang

The 30th verse of the chapter Anbiya is translated as follows:

Do those who disbelieve ever consider that the heavens and the earth were at first one piece, and then We parted them as separate entities; and that We have made every living thing from water? Will they still not come to believe? (Anbiya 21:30)

According to some scholars of Qur’anic exegesis, the phrase ratq (joined together, one piece) and fataqnahuma (We parted them) can be alluding to the moment of the Big Bang. As we have tried to summarize above, the entire universe was a single and very small mass and then started to expand and grow. As the universe expanded, the matter it contained began to expand and occupy a larger volume. As the universe expanded, its contents also began to separate from one another. So the phrases mentioned might be alluding to this chain of events. Together with that, some scholars thought that this verse alludes to the formation of the solar system, earth, and its atmosphere. The reason is that the verse continues with referring to the creation of living things. Accordingly, ratq might be referring to the phase when the solar system was a single mass and fataqnahuma might be referring to the planets and the earth breaking away from the sun and the formation of the atmosphere. It should be noted that systems forming within galaxies are also considered in the Big Bang model, which is used for referring to all of the phases from the time of zero to ours. Therefore, both possible explanations can be related to this model.

Another phrase which can be related to the Big Bang is the “Originator (Fatir) of the heavens and the earth” used in many different verses (e.g. Yusuf 12:101). Similarly, there is another verse expressing this reality with a verb from the same root (fatarahunna): …your Lord is the Lord of the heavens and the earth, Who has originated them each (Anbiya 21:56). Normally the phrase “fatara” is translated as “created.” In his study of Qur’anic exegesis (not available in English), Hamdi Yazir (1877-1942) points to the fact that the root “fatara” means to “split” or “split lengthwise,” and to originate something for the first time without a prior model. When these meanings of “fatara” are taken into consideration, “Originator (Fatir) of the heavens and the earth” can be an allusion to the Big Bang. Let us remember the fact that the Big Bang particularly refers to the very moment of the first creation. Therefore, the meaning “to originate something for the first time without a prior model” might be referring to this quality of the Big Bang. In addition, the word “split” expresses the moment of this great explosion better than the word “bang”; and so the beginning of space-time can be compared to splitting of a seed and its emergence.

One of the alternative meanings of “fatara” mentioned by Yazir, “split lengthwise” is very interesting. One of the important misconceptions about the Big Bang is to imagine that the universe was born in a certain spot and began expanding within another space. The Big Bang did not take place at a single spot. According to our theoretical understanding today, the entire space came into being altogether in a single moment. In other words, the Big Bang took place everywhere. When we consider the meaning “split lengthwise,” it might be an allusion to the fact that the Big Bang did not take place at a single point.

Conclusion

Considering the points we have tried to summarize above, the Qur’anic verses related to the creation of the universe can be defined as evidently miraculous. Surely, it is possible to expound on the subject from different aspects. For example we can think about a relation between the phrase “the seven heavens” used in many different verses in the Qur’an and the different phases after the Big Bang (although it is not possible pinpoint the exact number of these phases, figures like seven or seventy are metaphorically used in Arabic for referring to something in relevant multitude). Or they might be referring to some extra dimensions suggested by certain theories (The String Theory, one of the most-studied theories in recent years suggests the existence of seven extra dimensions).

Finally, we would like to underline that this article is an elementary attempt. What needs to be done more seriously is to form a board of scholars, particularly from the fields of cosmology and Qur’anic exegesis, and evaluate systematically all the verses related to the subject, and then try to analyze and understand them without any biased opinions. Such a study can provide deeper insight into the Qur’anic message.

Ali Kaya is a professor of physics in Bogazici University, Istanbul.

Note: This article was translated from Turkish by Korkut Altay.

For a long time astronomers have talked about the nine planets orbiting the Sun. These nine heavenly bodies have always been more special than other objects orbiting the Sun, such as asteroids and comets. The nine planets are larger than others; you can see some of them in the sky even with the naked eye if you know where to look. In September 2003, astronomer Mike Brown of Caltech and his colleagues announced the discovery of a new object in the sky, then named 2003 UB313 Eris, which is 27% larger than Pluto. This made astronomers reconsider the definition of a planet, thereby making Pluto and Eris two of the new category of objects orbiting the Sun dubbed “dwarf planets.”

While astronomers are engaged in the debate on planet definitions, astrophysicists still have not agreed about how planets were created. In fact, the journal Science recently put the birth of planets on the list of the top 125 questions scientists will tackle in the next quarter century.1 The comment ended with: “Planetary systems around other stars should provide clues.”

The reason scientists are interested in extrasolar planets- planets orbiting other stars, or exoplanets in short- is not limited to their curiosity about how planets were created. The second major motive for exoplanet research is the attempt to detect another “habitable” planet. NASA’s Origins Program,2 for example, is attempting to answer the question, “Are there worlds like the Earth around nearby stars? If so, are they habitable, and is life as we know it present there?” This is one of the major questions the new field of astrobiology is striving to answer.

In this article, we give an overview of planets and exoplanets with an emphasis on the critical conditions for life on a planet.

Planets and Exoplanets

The International Astronomical Union’s 2006 definition of a planet states that a planet is a celestial body that (1) is in orbit around a star, (2) has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round shape) but is not itself a star, and (3) has “cleared the neighborhood” around its orbit.

According to this definition, Pluto is indeed not a planet as its “moon” Charon is half the size of Pluto, whereas the moons of all other planets are much smaller than their respective parent planets. In addition, Pluto’s orbit is not as “clean” as the orbits of other planets.

Having introduced the new planet definition, we want to emphasize the first and foremost condition: a planet has to be in orbit around a star-not around the Sun. According to NASA Jet Propulsion Lab’s PlanetQuest website, as of August 2007, about 250 exoplanets in 99 planetary systems have been discovered. (The site exoplanets.org gives 228 planets around nearby stars.)

Discovery of solar planets is not too challenging: you take a clear picture of the same portion of the sky periodically, and compare the successive pictures. If you see an object that changes its position, then you can be sure that it is an object orbiting the Sun. Because stars are very far away compared to bodies orbiting the Sun, they seem stationary relative to us.

To give a sense of how far the stars are from us, think of the nearest star, Proxima Centauri, which is 4.3 light years away. One light year is the distance light travels in one year, which is 5.88 million million miles. If you fly a supersonic jet-a jet that can break the sound barrier (765 mph), such as the SR-713 or the MiG-25R, which can reach three times the speed of sound in the air-you would have to fly for about 1 million years nonstop to arrive at the nearest star. The most distant planet, Uranus, is about 0.002 million million miles away from the Sun, which is more than 12,000 times closer than Proxima Centauri-your trip to Uranus with a supersonic jet will take only about 80 years.

Exoplanets are as far away as stars. Therefore, it is impossible to detect them using the simple picture-the-sky method utilized for the solar planets. Every star with planets in its orbit is affected by the mass of the planets. This causes the star to sway back and forth. With extremely sensitive instruments measuring the Doppler shift in the frequency of light received from the star, the effect of the planet on the star can be detected.4 Another method is called astrometry: precise measurement of the positions of the stars relative to very distant stars, which appear stationary because they are far away. Small movements of the star because of the presence of planets can be detected.5

Direct optical detection of exoplanets is extremely hard, as they do not give off their own light. In the presence of the bright star, the planet becomes totally invisible. There are a few solutions. In the transit method, a planet blocks some of the star’s light as it transits past the star.6 Sensitive instruments can detect such small dips in the brightness of the stars. Also, interferometric detection7 can be used to detect the extremely weak light from the planet. Another optical detection method is called the “choronograph,” which is used to physically block the glare of the parent star, exposing the planet.

How are planets created?

The motion of a planet around the Sun can be described using two conservation laws-conservation of energy and conservation of angular momentum. Based on the understanding of orbital mechanics and the well-known laws of motion (first published in their entirety by Newton), it has become routine to place satellites in orbit around different planets to conduct various studies. Although science has been quite successful in describing planetary motion, we still do not know how planets were created. The conservation laws mentioned above do not determine the number, orbits, rotation directions, sizes, or type-rocky or gas giant-of planets. Initial conditions play a significant role; initial mass distribution around the star, the size of the particles orbiting the star during the early stages of the star’s life, and the initial orbits of these particles-when considered with the laws of motion, conservation laws, and the law of gravitational attraction-result in different planet-creation scenarios.

There are currently two main theories of planet creation, the gravitational instability and core accretion theories. In the gravitational instability theory, planets form during a rapid collapse of a dense cloud. In the core accretion theory, planets start as small rock-ice cores that grow as they gravitationally acquire additional mass.8 By detecting planets recently created around different stars, scientists hope to test these theories.

Search for life on exoplanets

Diverse life forms on the Earth are taken for granted. The average individual does not think much about the inner workings of life and the conditions that make life possible on the Earth.

Earth is a rocky planet that contains heavier elements, such as silicon, iron, and so on. We know that heavier elements were created during the supernova explosions,9 which comprised a few generations of stars, and therefore more than a few billion years. In a galaxy that is very young, one does not expect there will have been enough supernova explosions to produce heavy elements.

In an old galaxy, however, one does not expect to see radioactive elements. Thus, the planets that form in an old galaxy might be as dead as the moon because there will not be enough radioactive fuel. The Milky Way, our galaxy, is neither very young nor very old. Note that ages of galaxies and stars are in the order of billions of years-our sun is estimated to have been created about 4.6 billion years ago, and it is a middle–aged star.

In the Milky Way, our sun is placed at just the right spot, about halfway from the center.10 At the core of our galaxy, the density of stars is so high that they collide with each other. At the outer extremities, at the rim of the galaxy, the star density is too low to generate the heavier elements that make up planets as very few supernova explosions are expected.11

The orbits of all planets are elliptical, but very close to being circles. This is very significant for a planet if life is to prosper. Eccentricity is a measure of the elliptical shape of an orbit. A perfect circular orbit has an eccentricity of 0 (zero), and as the eccentricity comes closer to 1, the orbit becomes like a sausage. The earth’s orbit around the sun has an eccentricity of 0.067, very close to a perfect circle. If the eccentricity were to become 0.3, the average global temperature would become 73 F (23 C), compared with 58 F (14.5 C) on the Earth now, and, “some parts of the African, South American and Australian interiors heat up to 140 F (60 C)” when the Earth passes closest to the Sun,” according to Darren Williams and his colleagues of Pennsylvania State University.12 On an orbit with eccentricity of 0.4, the average temperature would increase to 86 F (30 C). Given the current scientific opinion on global warming and how catastrophic conditions could become because of a few degrees increase due to increasing amount of carbon dioxide in the atmosphere, you can imagine how unbearable the Earth would become for many complex life forms. Therefore, for a planet to bear life on its surface, its orbit must be at an optimum range of distances from the parent star, which is dubbed the “habitable zone.”

All planetary orbits around the Sun-not only that of the Earth-are nearly circular, and they do not cross each other’s orbits. If there were a number of planets with highly eccentric orbits around the Sun, some of them would cross the Earth’s orbit increasing the probability of a collision.

Obviously, a planet with life as we know it on Earth would need to be a rocky planet. In the solar system only four planets (Mercury, Venus, Earth, and Mars) are rocky planets; the other four (Jupiter, Saturn, Uranus, and Neptune) are gas giants.

The existence of gas giants, Jupiter being the largest of all, appears to be very important, too. Meteorite collision is a likely Doomsday scenario for the inhabitants of the Earth. In fact, meteorite collisions are cited as the main cause of the extinction of many species from the face of Earth in its several billion-year history.13 Jupiter is about 5au away from the Sun-1au is the mean Earth–Sun distance, nearly 150 million km-and as the most massive planet it plays a critical role in protecting the Earth from meteorites and comets.

In addition to all these astronomical conditions, the Earth has a magnetic belt that protects it from charged particles ejected from the Sun and other bodies. The Earth has an atmosphere,14 and the presence of water is absolutely critical for life.15

Of the almost three hundred exoplanets so far identified, most of them are gas giants as massive as Jupiter-more than 300 Earth masses. Therefore, scientists do not expect a glimpse of life on them. Recently, Christophe Lovis of the University of Geneva and his colleagues reported three low-mass planets orbiting the nearby star HD 69830, described as “hot-Neptunes” or “super-Earths”, as their masses are from 5–20 times the mass of the Earth. Scientists predict that two of these planets may be rocky planets based on theoretical calculations.16 For more conclusive results, however, telescopes with much higher resolutions are needed. Such telescopes are expected to be operational within a decade.

In conclusion, research interest in exoplanets originates from questions about the mechanism of planet creation, and the attempt to find planets where life can exist as we experience it on our blue planet. We do not know whether we will be able locate other worlds similar to the Earth with their own inhabitants. One thing we know, however, is that life is only possible through a great many critical conditions acting together in stars and planets as well as in cells and molecules. Life is very special indeed. Although the existence of other planetary systems suggests that our solar system is not as unique as once thought, with its “blue” planet -a planet that can support biological life-it still seems absolutely unique. Many scientists think, however, that with better tools and methods it is only a matter of time before we locate an Earth-like exoplanet. Time will prove or disprove their predictions.

Dr. Ertan Salik is an Assistant Prof. of Physics at California State Polytechnic Univ, Pomona. As well as teaching and conducting physics research Dr. Salik is currently involved in many education programs.

Notes

1. Science, Vol. 309, No. 5731, pp. 1–204 (2005).

2. NASA Origins program: http://origins.jpl.nasa.gov and http://origins.stsci.edu/

3. http://www.sr-71.org/ Accessed 2008-07-26.

4. Struve, Otto. “Proposal for a project of high-precision stellar radial velocity work”, The Observatory 72 (1952): 199–200, http://en.wikipedia.org/wiki/Doppler_spectroscopy Accessed 2008-07-26.

5. http://www.planetary.org/explore/topics/extrasolar_planets/extrasolar/astrometry.html Accessed 2008-07-26.

6. Charbonneau, D.; T. Brown; A. Burrows; G. Laughlin (2006). “When Extraslar Planets Transit Their Parent Stars”. Protostars and Planets V, University of Arizona Press.

7. Exoplanet detection using a nulling interferometer, Manuel P. Cagigal and Vidal F. Canales, Optics Express, Vol. 9, No. 1, 2 July 2001.

8. http://planetquest.jpl.nasa.gov/news/giantRockyCore.cfm Accessed 2008-07-26.

9. Gedik, Nuh. “Supernova Explosions and a Miracle of The Qur’an,” The Fountain, April-June 2006.

10. Weed, William Speed. “Circles of Life,” Discovery, November 2002.

11. See Charbonneau 2006.

12. Weed, 2002.

13. Gonullu, Omer Said. “The Message of Meteorites,” The Fountain, January–March 2005.

14. Cakmak, Osman. “A Journey in the Atmosphere,” The Fountain, January–March 2002.

15. Gedik, Nuh. “The Miracles of Water,” The Fountain, January–March 2005.

16. Lovis, Christophe et al. Nature, 441, 305–309 (18 May 2006).

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