This week in the press, there was a report about a new theory of the origin of our universe; read about it by clicking HERE. The theory says that the universe goes through an endless series of big bangs and big crunches. According to conventional science, if we go back in time - way back - and approach the time of the big bang, we will come to a singularity, in which density, temperature and curvature become infinite; a point where all the laws of physics break down. This is very troubling since infinities are not very welcome in physics equations. However, using the concept of Loop Quantum Gravity (LQG), it has been shown - by running the LQG equations backwards - that the singularity can be avoided. As the universe collapses, it reaches a point in which it bounces back in a big bang, and the process repeats with the universe expanding. In an endless cycle of big bangs and big crunches, no two universes will ever be the same. The big bang and big crunch cycle is not new; what is new is that, according to this theory, the birth of our universe is not associated with a singularity and every successive universe is different from the one that preceded it.
But what is LQG? LQG competes with string theory as a "theory of everything" and, like string theory, is an incomplete and unproven (unprovable?) theory. It was developed by rewriting the equations of general relativity in a quantum structure. In this framework, spacetime is made up of tiny loops of 10^-35 metres in diameter. Spacetime is a network that links these loops together in an abstract way. How do we avoid a singularity and why is each universe different? Well, I'm not a physicist and I'm not familiar with the mathematics behind LQG, but I think I can guess how it works. In the case of a big crunch, as the volume becomes ever smaller, it reaches the point of the big bang. Since the universe is composed of finite loops, there can never be a singularity. When the universe reaches its most compact state, it bounces back and forms a new expanding universe. But it will be different from its predecessor. This is due to the uncertainty principle. At the time just before the "big bounce" - when the universe is very small - the amount of uncertainty is very different from that at the time after the big bounce, so the new universe will be different. To understand better how the uncertainty principle brings about a universe that is different from its predecessor, imagine a thought experiment in which we have a bunch of atoms moving around in a closed box. Let's say we try to reverse the motion of every atom at the same time, so that they all return to their starting positions. This makes no sense because we need to know the position of every atom precisely; its velocity must be precisely determined and then reversed while the atom stays in the same position. But Heisenberg's Uncertainty Principle tells us that this is impossible; it says that we can never simultaneously measure the position and speed of something to perfect accuracy; this is an intrinsic uncertainty and it has nothing to do with the way physicists conduct their experiments or the accuracy of their instruments. So a system such as our universe is, in fact, not reversible because of the uncertainty of the starting conditions.
What does this say about the possibility of life emerging in our universe? Albert Einstein once said, "What really interests me is whether God had any choice in the creation of the world" (of course he was not referring to a personal god). Indeed, slight changes in the constants of nature - constants such as the strength of gravity, the speed of light, the masses of subatomic particles and the strengths of the weak and strong forces - could have made a completely different universe to the one we know and love - perhaps one where life could never arise. Given that there have been many cycles of big bangs crunches and bounces, this universe may have "won the jackpot" where all the constants of nature are set such that the conditions are just right for life to arise and for you and I to be born.
If you are a Hindu philosopher, none of the above should surprise you. Hindu philosophy has always accepted the notion of an alternately expanding and contracting universe. In his book Cosmos, Carl Sagan pointed out how, in Hindu cosmology, the universe undergoes an infinite number of deaths and rebirths, and its timescales are in the same ballpark as those of modern cosmology. Here is a quote from Cosmos:
"There is the deep and appealing notion that the universe is but a dream of the god who, after a hundred Brahma years, dissolves himself into a dreamless sleep. The universe dissolves with him - until, after another Brahma century, he stirs, recomposes himself and begins again to dream the cosmic dream.
Meanwhile, elsewhere, there are an infinite number of universes, each with its own god dreaming the cosmic dream. These great ideas are tempered by another, perhaps greater. It is said that men may not be the dreams of gods, but rather that the gods are the dreams of men."
So, according to Hinduism, the universe is a dream of some god. In my experience, no two dreams are precisely the same, and most of my dreams are of implausible scenarios.
To get an idea of the Hindu timescales, here are some figures: The smallest unit of measurement is the yuga - or era. Each yuga is preceded by a dawn and followed by a dusk which constitute the transition between them. A complete cycle - a mahayuga - consists of four yugas of unequal length. The longest yuga is the first one in the cycle and the shortest is the last one. I won't go into the meanings of each yuga - suffice to say that we are in the last yuga, called the kali yuga. It is believed that we entered the kali yuga in about 3200 BC. Here are the lengths of each of the 4 yugas in solar years:
Satya yuga: 1,728,000 years
Treta yuga: 1,296,000 years
Dwapar yuga: 864,000 years
Kali yuga: 432,000 years
The cycle repeats itself and there are 1000 mahayugas in one day in the life of Brahma (Hindu god). This day of Brahma is called a kalpa and, if you've done your arithmetic, it is 4.32 billion solar years long. Another kalpa is a Brahma night.
In terms of the age of our universe, these Hindu units of time are similar to those of modern cosmology (scientists say that our universe is around 15 billion years old). Compare this with the Christian fundamentalist view that the Earth is a mere 6000 years old. Hinduism is the only major religion that accepts the idea of universes that undergo cycles of expansion and contraction. If we take away all of the mythological nonsense from Hindu religion and replace it with mathematical nonsense, we come very close to the modern religion of cosmology. If you like, we are characters in Brahma's cosmic dream, and we are trying to understand his mind by analyzing and interpreting his dream.
Thoughts about science, human nature and other stuff.
