Albert Einstein devoted the second half of his professional life to the search for a unified theory of physics. Since then it has been probably the most engaging scientific passion to construct such a theory. Stephen Hawking, the greatest mind on earth at the beginning of the 21st century, concludes his A Brief History of Time with a hope that someone will come up with a unified theory of physics. Richard Dawkins, another great mind, suggests that a unified theory of physics will put an end to the idea of God, that has seized the human mind for millennia. The investment of billions of dollars in the Large Hadron Collider is partially driven by the search for the unified theory.
The search for the unified theory has become intense in the last 50-60 years due to the lack of harmony between Einstein’s General Theory of Relativity, which explains gravitational force governing planetary bodies, and quantum physics, which explains electro-magnetism at the subatomic level. Since the universe is made of atoms, and atoms are made of protons and electrons, scientists believe that the laws of nature determining the behaviour of protons or quarks have to be the same as those shaping supernova. Some scientists hope that a string theory may pave the way for the unified theory. In fact, Hawking also shares this hope in his recent writing. Some others are not so hopeful.
There is no one string theory but indeed there are several of them. String theories allow more than three dimensions of space and more than one universe. The search for a unified theory has therefore resulted in a search for more dimensions. It has raised questions whether there was another universe before the Big Bang created ours, and if indeed there are other universes existing at the moment, with their own laws of nature. It has also opened the debate whether the universe will ever contract to singularity, or whether it will merely crunch to a certain extent and expand again, or whether it will continue to accelerate without any limit.
The search for a unified theory has also raised questions about whether all phenomenon of nature can be measured by mathematics. The constants of nature, in simple numbers, precisely explain how one subatomic particle is related to another. The fine structure constant explains dynamics between electrons and photons. The gravitational constant explains the relationship between gravity, protons and speed of light. John Barrow summarises in his book The New Theories of Everything that the sizes of all astronomical bodies are determined by the relative values of these two constants alone. On the other Barrow explains that it is not possible to compute and predict everything with a formula – for instance emotions, creativity and anguish.
Since the unified theory of physics is often equated with the Theory of Everything by physicists, who believe that science is the only explanation of nature, the debate on the unified theory gets blended with a debate on philosophy. There are some commonalities between the laws of nature and the laws of society. Whatever expands does collapse when it runs out of energy. When something collapses into a black hole, it cannot be retrieved again. In fact, it attracts into itself all objects that are near. These laws can be observed in the functioning of science as well as society. But as we move away from phenomena that can be computed, physics encounters its limitations.
The world has entered the era of petaflop computers, those which are capable of 1000 trillion calculations per second. China, Japan and the United States have several computers between 2-3 petaflop capacity. They are engaged in a race to produce a 10 petaflop computer and will almost certainly succeed in a few years time. When they do, they will begin a new competition for a 100 petaflop computer and then the computers will be far ahead of human brain in their ability to compute. Such 10 or 100 petaflop computers will be able to produce spacecrafts and map the genome code at a low cost. But there is no indication that they will be able to contain human greed, jealousy and excessive ambition.
The unified theory of physics, if constructed, will therefore not be the Theory of Everything, since it may not be able to explain the phenomenon of mind and therefore of human nature. We can extend the same logic to intelligent beings, if they exists somewhere in the universe. If these extraterrestrial beings are like machines working on the basis of mathematical formulae, the unified theory will be able to explain their behaviour. But if they are even more irrational than human beings, no single theory will be able to explain their thought process, even though it might explain the elements that construct them. If these beings are able to transform, as depicted in mythology, from one substance to another or from substance to a non-substance and back again at their own will, the unified theory of physics, based on constant equations between various particles, will not be able to explain their thought process or their existence.
I may be expressing such scepticism because knowledge that exists in the early part of the 21st century is not adequate to envisage a theory that can provide a unified insight into all probable laws of nature and the functioning of the mind. But who knows whether in another 100 or 1000 or 10000 years our knowledge base will expand so significantly that it will deliver the Theory of Everything. Whether we exist for such a long time will ultimately depend on our mind, irrespective of our ability or failure to understand its working.
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