In a 2014 article for The Conversation, Prof. Jonathan Borwein, from Newcastle University, and Dr. David H. Bailey, from the University of California, Davis, stated, "In recent years physicists and cosmologists have uncovered numerous eye-popping remarkable instances of apparent 'fine tuning’ of the universe." They gave many examples. For instance, according to Borwein and Bailey, if the strong force, which is the force that binds protons and neutrons together to form the nucleus of an atom, were slightly stronger or slightly weaker – by even just 1% in either direction – there would be no carbon or any heavier elements anywhere in the universe. This would be a calamity, as the Earth is kept in its orbit around the Sun by the gravitational force between them. Electrons are kept in atoms by the electrical force that attracts them to protons. Since equal charges repel each other, the protons in atomic nuclei would fly apart, unless a more powerful force holds them together. That force is called the strong nuclear force. It holds both protons and neutrons together as long as they get sufficiently close.
In physics, there are certain physical quantities that play a central role in the science, such as the mass of an electron or the speed of light, also known as the gravitational constant.
"We do know the values of these fundamental quantities very well," said astrophysicist Prof. Brian Koberlein in an article published recently on his website. "The mass and charge of an electron are known to about one part in a billion. The gravitational constant, perhaps the least well measured, is known to about one part in ten thousand," he added. Prof. Max Tegmark, who is a world famous physicist from the Massachusetts Institute of Technology, said that most of the parameters affecting low-energy physics appear fine-tuned at some level in the sense that changing them by modest amounts would result in a qualitatively different universe.
"If the electromagnetic force were weakened by a mere 4%, then the Sun would immediately explode. If it were stronger, there would be fewer stable atoms," noted Tegmark in the book Science and Ultimate Reality: From Quantum to Cosmos, published by Cambridge University Press. Tegmark continued, "If the weak interaction (which is one of the fundamental forces in physics) were substantially weaker, there would be no hydrogen around, since it would have been converted to helium shortly after the Big Bang. If it were either much stronger or much weaker, the neutrinos from a supernova explosion would fail to blow away the outer parts of the star, and it is doubtful whether life supporting heavy elements would ever be able to leave the stars where they were produced. (The heavier elements, such as carbon, oxygen, and iron, were made in the nuclear furnace of high mass stars. Upon the death of stars, these elements, along with even more massive nuclei created during the supernova, were thrown out into space.)
Prof. Tegmark gave some more fascinating examples: "If the protons were 0.2% heavier, they would decay into neutrons unable to hold onto electrons, so there would be no stable atoms around. If the proton-to-electron mass ratio were much smaller, there could be no stable stars, and if it were much larger, there could be no ordered structures like crystals and DNA molecules."
And here are some examples of "fine tuning" mentioned by Dr. Luke Barnes from the Sydney Institute for Astronomy, in his article, "The Fine-Tuning of the Universe for Intelligent Life":
"If gravity were repulsive rather than attractive, then matter wouldn’t clump into complex structures. If the strong force (the force that binds protons and neutrons together to form the nucleus of an atom) were a long rather than short-range force, then there would be no atoms. Any structures that formed would be uniform, spherical, undifferentiated lumps of arbitrary size and incapable of complexity. If in electromagnetism, like charges attracted and opposites repelled, then there would be no atoms. As above, we would just have undifferentiated lumps of matter."
Another example of fine tuning is the fine structure constant, which is also known as alpha. It’s the measure of the strength of the electromagnetic force that governs how electrically charged particles interact. Its value is nearly equal to 1/137 (or to 0.007297). Richard Feynman, who is one of the top physicists of the 20th century and a Nobel laureate, called the fine structure constant "a magic number."
"If alpha were >0.1, stellar fusion would be impossible," stated University of Cambridge theoretical physicist Prof. John Barrow.
Physicist Gerald Schroeder from the Massachusetts Institute of Technology quoted the words of Prof. Michael Turner, an astrophysicist at the University of Chicago and Fermilab: "The precision (in the universe) is as if one could throw a dart across the entire universe and hit a bull’s-eye one millimeter in diameter on the other side."