Mr joseph vempeny Posted on : 07/02/2008 19:45:08

Cosmology

Origin and Evolution of the Universe

“Physics, beware of Metaphysics”: Isaac Newton

When did all this start, and how? Was there a beginning at all? Or was the universe always like this? A few centuries back there were no such doubts. Everything was simple and clear. God, the Supreme being, the Almighty, created the universe and everything in it. In those days, the universe had at its centre the earth, with the sun, the moon and the stars as big or small lights in the sky. And the sky was the ceiling or vault of our world. All this changed with the advent of modern science and technology. With new resources at their disposal, the astronomers began to look deeper into space for clearer pictures and physicists began to formulate new theories on cosmology based on these findings. The wealth of new information about space and heavenly bodies that we had acquired in the last century is really remarkable.

The Static Universe

At the start of the twentieth century, the scientists used the old laws of Newton and Kepler to explain the dynamics of heavenly bodies. This model of the universe was static. The only movements were the rotation and revolution of the planets. The universe as a whole remained as it is. On this model of the universe, there was no beginning and there will be no end. Hence the question of how all this started was not relevant. This was the model on which Albert Einstein was building his theories of relativity. His theories on gravity were much more inclusive than those of Newton. His work encompassed not only the fields of gravity and astronomy, it included particle physics, nuclear energy, quantum mechanics, in fact every aspect of physics. People call him a genius and his work is considered to be thought-experiments. I would call him a prophet and his thought experiments ‘works of inspiration’.

Einstein could not understand why the universe was static. According to him, the gravitational forces should bring the galaxies closer and closer. The universe must be contracting. But there was no sign of such contraction. If the universe is not contracting it must be expanding, he argued - expanding, as if the galaxies are hurtling out into space following an initial explosion. There was no sign of such expansion either. Following his own dictum that imagination should come in where knowledge is lacking, he invented an imaginary repulsive force that exists in the empty spaces between galaxies. This overcomes or balances the force of gravity and prevents the universe from collapsing on itself in a big crunch. In his equations he termed this quantity, lambda one of the letters of the Greek alphabet. Later it was called the cosmological constant. His equations also included another quantity represented by another Greek letter omega, which decided the shape of the universe. Experimental evidences for most of his theories were to be obtained, one after another, during the ensuing decades, some even after his death.

The Expanding Universe

Einstein published his theories in 1917, complete with lambda, omega and all. Then in 1929, Edwin Hubble noticed a considerable red shift in the radiations from a very distant galaxy. This red shift indicated that the galaxy was receding from us rather fast. Hubble and others observed the same kind of red shift in the light from distant galaxies from every corner of the universe. This proved conclusively that the universe is expanding. In this model of the expanding universe, the cosmological constant, lambda of Einstein’s equations became irrelevant. Einstein accepted that the inclusion of lambda in his equations was the greatest blunder of his life, as it seemed at that time that the expanding universe could be explained without the inclusion of the cosmological constant.

Over and above the stars and galaxies previously known, there came into the field of man’s vision new and weird characters like, white dwarfs, red giants, quasars, black holes and supernovae. Some quasars are found as far as 12 billion light years away. The telescopes were not only looking far into space, but also back into the distant past. As light travels at 300 000 km per second, when we look at the nearest star we are seeing it as it was 4.6 years ago. This is because it is 4.6 light years away from us. When we look at a quasar 12 billion light years away we are seeing it as it was 12 billion years ago. Cosmology was becoming more complex and incomprehensible. The more we discover and learn, the less we seem to understand the essence of the cosmos.

The knowledge that the universe is expanding brought back the question of its origin. If it is expanding, where, when and how did the expansion start? The galaxies seem to be running away from each other like fragments from an explosion. Some explosion! Here came the great step in cosmology - the idea of the Big Bang origin. Though many other theories came up to challenge the Big Bang theory, it had survived for the last fifty years as the only sensible cosmic view.

According to the Big Bang theory of the fifties and sixties, the universe began some 15 billion years ago, as a primordial egg. (Sounds like Hindu mythology?). A Big Bang sent the fragments of this, far out into space and these began to develop into galaxies and stars. Today it sounds too farfetched even for scientists. It is, and always will be, beyond the scope of science and scientists to answer the questions, how and why, of the origin. It comes within the realm of philosophers and theologians and, may be, poets and prophets. To the question, where did the big bang event take place, the answer seemed quite simple. ‘It began at the centre of the universe’. But now we learn that it is not like that at all. The Big Bang did not take place at any point in space. Before the Big Bang there was no space at all. The event that started all this was the creation, not only of matter but also of space and time. The conclusions that the scientists make on the origin of the universe or its evolution keeps changing with new discoveries or findings at the last count (February 2003), the Big-Bang origin took place between 13 and 14 billion years ago. The explosion or whatever did not send matter hurtling into space but matter and space began expanding together with the progress of time.

The Accelerating Universe

There was no shortage of surprises for the astronomers and theoretical physicists working on cosmology during the last 80 years. And they kept on doggedly pursuing the elusive answers to crucial questions. The model of the expanding universe could get rid of the cosmological constant or lambda. But there were other concerns. Taken for granted that the galaxies and quasars and a host of others are running apart from an initial expansion, the laws of Newton and of Einstein dictate that they should eventually slow down, come to a stop and may be fall back on itself in the big crunch. Whatever the case, the universe must be slowing down.

The astronomers of the nineties, armed with advanced technologies like the Hubble space telescope, the very large telescopes (VLTs) and other resources, began to look for the signs of deceleration. Studying the red shift of supernova at various distances they could determine the rate of expansion at various stages in cosmic evolution. This should give conclusive evidence of the expansion slowing down, of deceleration. In the late nineties two separate teams were studying these red shifts. The evidence they found was the opposite of what they were looking for. Instead of slowing down, the expansion of the universe was speeding up or accelerating. This was in 1997.

How do we explain a universe that beats gravity and keep on expanding instead of slowing down? What do we do to fit this new observation into our model of the cosmos? The easiest way of course is to bring back the discarded lambda. Einstein’s cosmological constant was not a blunder after all. This repulsive force acting in empty space keep pushing the galaxies apart, overcoming the gravitational pull. This is what makes the expanding universe accelerate. Problem solved and everyone happy? Not quite. When lambda fitted in comfortably into the Big Bang model of the universe, omega began to cause problems. Omega stands for the material density of the universe and its value depends on the total mass of all the matter that makes up the whole universe. Einstein had predicted three possible shapes for the universe depending on the value of omega. The universe will be flat if omega equals one, open or saddle-shaped if omega is less than one and closed or spherical if omega is greater than one. It was also believed that the fate of the universe depends on its shape.

An open universe will keep on expanding forever and a closed universe will fall back on itself to end in a big crunch while a flat universe will eventually stop expansion but will not move backward to cause the crunch. In other words “density determines destiny”, as one scientist put it. To assess the density of our universe the value of omega was recently estimated by observing the effect the matter of the universe had in bending the cosmic background radiation, (CBR), the microwave radiation at 3 K, the telltale remnant of the Big Bang. These observations confirmed the critical density, omega to be one, leaving a flat universe. So far so good. But the troubles were not over yet.

Dark Energy

Here is the dilemma that faced the physicists at the turn of the millennium, the dawn of the twenty-first century. The fluctuations in the Cosmic Background Radiation pointed to a flat universe. Yet the latest, most reliable and accurate estimates of the total mass of the matter in the universe, including all the exotic forms of matter does not come anywhere near that needed for the critical density. The estimates show that the total mass can account for only 1/3 of the total mass required. Where do you go for the rest of the mass needed for the universe to be flat?

So we go back to good old Einstein who had taught us the principle of the equivalence of matter and energy through the equation E = mc2. And thus we get the new notion that our universe is made of one-third matter and two-thirds energy. But this is not like any of the ordinary forms of energy such as heat, light, microwave radiation etc. This was christened the Dark Energy: dark, because it cannot be detected, and energy, because it is not matter. To have the desired effect it has to be either matter or something equivalent to matter, which is energy. But in reality this does not sound like either matter or energy. But for argument’s sake let us acknowledge the existence of ‘dark energy’ that substitute for two-thirds of the matter in the universe. Still it is not smooth sailing for the cosmologist.

Physics or Metaphysics

For one thing, this concept of dark energy is not something that can be subjected to the common tools of physics, to be detected, measured, transformed or studied otherwise. This borders the mythical if not spiritual. Many noted physicists are not happy with the idea of dark energy for this reason. Secondly, the ratio of matter to dark energy needed to maintain the present state of the cosmos; the ratio 1: 2 is the least probable one of an infinite number of options according to some. Hence this is unbelievable to many of them. To explain this, some suggest that this form of dark energy has the ability to communicate with matter and its quantity is self-determined according to the needs. Does it not sound like an immense force with consciousness?

To get an idea of the immensity of this force, what we call antigravity or dark energy, another fact also must be understood. Consider the total mass of all the ordinary matter in our cosmos, the billions upon billions of stars, with all the planets, the dust and cloud, the gases hydrogen, helium, the strange massive objects like quasars and even more massive black holes. In normal sense of the term one could describe this as infinite. But wait a while; this is still finite. According to the latest assessment by the cosmologists, the combined mass of all the stars together make up only 1 % of the total mass of the universe. The stars together with the loose gases, dust and all forms of ordinary matter still make up only 5 % of the total mass of the mass-energy conglomerate that keep our universe in its present state of flatness. 30% of the mass is made up of what is termed invisible matter, something that cannot be detected. This is called dark matter. The scientists still do not know anything about the nature of this dark matter or dark energy other than that they are there. According to David Cline, the names, dark matter and dark energy are “expressions of our ignorance.” (Scientific American: Feb. 2003). The dark matter and dark energy together make up 95% of the mass of the universe. If all the known forms of matter of the universe make up only 5%, then the 95% is what one can call infinite. This infinite force with a consciousness that controls the shape and fate of the universe is what our forefathers called Omnipotent Force, Parasakthi (Sanskrit for supreme force) or in simple language, God. I am not implying that this force of antigravity or dark energy is identical to God. Far from it. What I mean in this context is that this almost infinite force is one of the ways in which the infinite God controls the cosmic evolution.

We are faced with one more problem of a different nature. If our universe were made of one-third matter and two-third dark energy, this repulsive energy would have prevented the matter from gathering together into galaxies, stars and planets. The sun and the earth should not be here and we should not be here. Yet, here we are! Some explain this by attributing more supernatural powers to the dark energy. According to them this energy knows when and how to increase or decrease in magnitude, when to maximise or minimise. It was a maximum during the first phase of cosmic evolution, a minimum during the period when galaxies and stars formed and again a high right now. This will explain why I termed this antigravity or dark energy ‘a force with consciousness’. Some other scientists explain away this problem by bringing in the ‘anthropic principle’ and yet others the ‘principle of quintessence’.

I do not claim to have understood these principles, but I have the suspicion that here we are passing from the realm of physics to that of metaphysics. Not that I have any problem with the metaphysical explanations of cosmology. In fact that is my very goal. I fully agree with the view that the present state of the universe cannot be explained by physical laws, that the expansion of the universe is controlled by a supernatural force, that the solar system, the earth and living beings are here, not by chance but by divine design. To make sense of these data and principles crowding in as we try to learn more about our world we have to correlate physics with metaphysics, complement cosmology with theology, supplement science with religion.

The Great Inflation

In the beginning, when God created the world, all that is in the universe - time, space, energy and matter - was contained in an infinitesimally small point known as singularity. The density, pressure and temperature of this singularity were infinite. This is the only instance where the term infinite can be aptly applied except in reference to God himself. 10-44 seconds after the creation, this point of singularity was still smaller in size than a proton. Next instant the great inflation started, the point expanding madly to the size of a mustard seed to tennis ball to football to a ball of radius of thousands of kilometres, to one of thousands of light years. The matter had not yet accreted to stars or galaxies. There was no explosion or Big Bang, only inflation. This is the view of the cosmologists at the start of the twenty-first century. Big Bang is replaced by inflation.During the first nanosecond (one billionth fraction of a second), matter was in its fifth state known as quagma or quark-gluon plasma – no ions, protons or neutrons yet. (The five phases of matter are solid, liquid gas, plasma and quagma). The four forces - gravity, strong nuclear force, weak nuclear force and electromagnetic force - were united as one force. Radiation had not started, and the cosmos was dark. After the first phase of inflation, about 100 million years after the origin of inflation, the radiation era started and there was light. (This is not from the Bible but from an article in the Time: 25 June 2001). And it was much later that matter somehow began to condense into galaxies and stars.

In the past we just assumed that it was only natural for matter in the universe to accrete into stars and planets by the action of gravity. But today, in the twenty-first century we know that it wasn’t as simple as that. It was not a natural process. If the dark energy were doing then what it is doing now and at the beginning of times – causing acceleration or inflation - the matter of the universe would never have formed into stars and galaxies. Hence we have to assume that the Almighty who guides and controls the evolution of the universe directly intervenes in these matters and that most happenings in our world are not just by chance but be divine design.

Alternate Theories

The preceding pages of this chapter were written at a time when the Big-Bang/Inflation theory was having the reign of the field of cosmology and astronomy. Half a century ago there were other theories such as the steady state theory and the oscillating universe theory. Carl Sagan, in his book ‘The Cosmos’ and the television series of the same title, had favoured the oscillating universe theory and compared it to the Cycles of creation and destruction as found in the Indian/Hindu Mythology. At the turn of the new millennium newest discoveries in the fields of cosmology and astronomy have confirmed the Big-bang model for the evolution of the universe. But this does not in any way mean that the scientists had the final say in the matter. The string theory, though not very popular now, could make a come back. It is not impossible that new discoveries and new theories could topple the Big-Bang theory or the ‘flat’ nature of the universe. The present assumption about the destiny of the universe is based on the assumption of the role of dark energy acting as antigravity and causing the universe to accelerate. But how far can we depend on this assumption? We have seen that the dark energy was a maximum during the early inflation era, a minimum when the galaxies and stars were formed and again a maximum now. What if the antigravity is to become a minimum again sometime in the future? Could it not cause the gravity to take over, put a break on the acceleration and start a deceleration to end in a big crunch? Could we reach the state of singularity again and start the process again with another inflation?

Theories may come to support or disprove these views but we wont be here to verify these. The relevant question I wish to bring out here is whether such a state of affairs will anyway affect the views I have presented here about the metaphysical nature of cosmic evolution? Will such developments affect my faith? There is an unequivocal negative as answer to this. Scientific views on the nature, creation or evolution of our universe could be changing and unsure. The theological view is never changing. The view the people the world over had held from the earliest times of human existence, the view that the universe and everything in it are the work of a creator will always hold true. Nor am I here trying to defend God. He needs no defense, no apology, not the least from me.

Fusion Reactors

For the last 50 years or so scientists have gone out of their way to invent an economical or practical fusion reactor, the only possible source of plentiful clean energy that the world need so much. The existing nuclear reactors that supply the power for many cities, ships and submarines work on the principle of nuclear fission, or splitting the nucleus of heavy elements like plutonium and Uranium. These leave so much radioactive waste, very harmful and impossible to dispose off. The fusion reactors on the other hand work on the principle of the fusion of hydrogen or deuterium atoms to form nuclei of heavier atoms like helium or lithium. These would leave no radioactive waste like the fission reactors, no pollutants like the thermal power plants and no ecological problem like the hydroelectric power plants. In both fission and fusion some small fraction of the matter involved in the nuclear reactions is converted into energy according to the equation E = mc2. Though the scientists or engineers could not produce such reactors on a viable scale there is no shortage of these in nature at large. Every star including our sun is a fusion reactor that produces energy and creates heavier atoms all the time.

The observations on the nature of the cosmic background microwave radiation tell us that the porridge of matter at the end of the first phase of inflation was not smooth but very lumpy. The small lumps formed what are the galactic clusters of today and the big lumps formed the super clusters of galaxies. Further expansion of this porridge of matter made empty spaces, first between the lumps and later, within the lumps. Gravity took control and the first proto-galaxies and stars were born. The first generation stars were made exclusively of hydrogen and helium. As gravitational forces brought this small lump of matter closer and denser the pressures and temperatures soared to such heights that nuclear fusion reactions began in earnest and these stars began to shine with ever increasing brightness, emitting all bands of electromagnetic spectrum from radio waves at one end to X-rays at the other. In this process, these stars, these fusion reactors, while giving out heat, light and other forms of energy were also going into full-scale production as the factories producing the other heavier elements. The heavy elements like iron and nickel are produced in the second-generation stars born out of the debris of the first generation stars. Our sun is a third-generation star. The very heavy elements like iodine gold or uranium are not formed even in the most massive of the third generation stars according to the latest observations. Scientists attribute the creation of these to neutron star collisions or some other phenomenon.