Recently, during an exhaustive dialogue with Roger Penrose, a novel picture emerged about the structure of the universe — a product of the intensely creative passion of Penrose about space and time in which our universe floats. We also discussed ‘consciousness’ at the end of our dialogue. Clearly, consciousness is a necessary element in this discussion.

Penrose has invented over the years the concept of ‘cycles of time’, going beyond the singularity of time or the point before which time cannot be defined, (loosely speaking) at the zero (singularity) time the universe was born in a ‘Big Bang’. Ironically, he is one of the inventors of singularity and now goes beyond that time. His time, now, has no beginning, no end — which is philosophically extremely attractive. But what is the science behind this almost crazy idea? At one stroke this throws away the very concept of the beginning of the universe in a ‘Big Bang’, and along with it some associated ideas such as inflation.

The universe is surprisingly smooth and uniform. To understand that, physicists have introduced the idea of inflation — that in very early times, almost immediately after the Big Bang, the universe expanded rapidly and exponentially. This idea is still very fashionable and considered a major milestone in cosmology.

The centrepiece of the ‘cycles of time’ argument is to do with entropy and black hole. Entropy is a measure of randomness or chaos and it goes on increasing, although the overall entropy has to be conserved by definition. If one keeps on losing overall entropy, the universe could not have existed at all. This is as per the dictate of the most fundamental law of nature, the second law of thermodynamics. Penrose uses the second law cleverly to devise the ‘cyclic times’.

A black hole nearly always is the remnant of a collapsing star. How does a star collapse ? Our sun is a star, fortunately not big enough. Light or, say, sunlight, is produced inside the sun because of nuclear fusion: fusing some amount of mass gets converted to energy. The hydrogen bomb is a fusion bomb. Now, if the star is big enough to cross the Subrahmanyan Chandrasekhar limit, about 1.4 times the mass of the sun, the star is likely to collapse.

A nuclear fusion burns itself out after some time (the sun will have the same fate after some millions of years) and gravitational pull takes over. The star begins to shrink through gravity. There is no way to prevent that shrinking, and it eventually collapses to a black hole. Our familiar sun will never end up as a black hole, it just hasn’t enough mass. The sun eventually will end up as a red giant, leading to our planet’s extinction.

The gravity of the collapsed star becomes so strong that nothing can escape from its interior, not even light (hence the name, black hole). Any object which comes near the black hole is gobbled up by its almost limitless gravitational appetite. However, Stephen Hawking, in a most original work in the 1970s, showed convincingly that as per (again) the second law of thermodynamics and elementary quantum mechanics, black holes can radiate energy. This is known as Hawking radiation.

Black holes are the most important reservoirs of entropy. Penrose argues that with the expansion of our universe it cools, and becomes even cooler than the coldest black holes. At that time the black holes begin to radiate away (the so-called Hawking radiation of the black hole from the surface can, depending on the entropy). The black holes go on shrinking and eventually disappear.

The rather involved argument Penrose puts forward at this stage implies that “nothing is left ultimately which can be measured in any scale and the Big and Small become the same”. There will be no distinction between big and small at that level. He goes on to propose his fantastical scheme that the “entire history of the universe is just one stage in a succession”. What we think of as the Big Bang is not the beginning. It is the continuation of the remote future of a previous aeon.

That exactly is at the core of the cyclical time idea. From one aeon to another aeon, the universe goes through an eternal cycle, with no beginning and no end.

The question, I asked Roger was, “How on universe (not on earth, mind you) do we know that this is what is happening?” The cosmos is filled with a beautifully fine-tuned radiation (perfect black body radiation) called cosmic microwave radiation (the radiation left over from the Big Bang) that would reveal evidence of events taking place in the aeon before ours, such as encounters between super massive black holes. When galaxies collide, the central black holes may spiral around and swallow each other up, causing enormous bursts of gravitational radiation as a direct consequence of the “swallow up”. Such a burst from the previous aeon at the last stage of the universe of that aeon would leave its tell-tale marks as circles around which the temperature is almost anomalously normal.

Penrose and his colleague, V.G. Gurzadyan, see such circles in the cosmic microwave background radiation: the temperature anisotropy was mapped by Wilkinson Microwave Anisotropy Probe and the discoverers went on to win the Nobel prize. Penrose and Gurzadyan claim that these rings are the signals of the death throes of the last universe in the previous aeon.

So, the great uniformity of the universe originates before the Big Bang, from the tail end of a previous aeon that saw the universe expand to become infinitely large and very smooth. That aeon in turn was born in a Big Bang that emerged from the end of a still earlier aeon and so on, creating potentially an infinite cycle of time with no beginning or end.

Such a fantastic and grand idea is not going to be accepted easily, I tentatively suggested. Indeed a whole host of scientists armed with scientific armoury have already challenged it vigorously.

Roger pointed out his great mathematical discovery, “the twister theorem”, is properly understood by few only now after about 25 years. It will take considerable time before his idea is accepted, if at all. I put the question to Roger that today the pressure of contemporary fashion and the market value of research pose a serious threat to true originality. Penrose immediately agreed. A young man in his thirties today has very little hope of making his ‘revolutionary’ ideas stay — he will be simply hounded out — we both agreed. Second, a lot of money and enormous talent, and so-called contemporary seminal work have gone into the standard Big Bang theory and the associated inflationary theory. If the idea of Penrose and Gurzadyan stands the test of time, a vast amount of work done for the last 30 years will turn obsolete, if not simply wrong. Nobody swallows that in today’s world easily.

We rounded up our dialogue with a touch of absurd humour: “Any mark left by the inhabitants of the last aeon?” “They indeed could have existed but that information we can never have,” — it is lost forever in the black holes of that aeon.

Towards the end we touched upon the idea of consciousness and on the great scientific debate going on in the contemporary world. Penrose went back to his book, The Emperor’s New Mind, where he asserts that computers will not achieve any conscious understanding. He has reasons to believe that to understand (and we do not fully understand) consciousness we have to reach out to the limits of quantum mechanics. Microtubules (minute structures in the body’s cells) are the best candidates in the brain for which this might happen since they are so tiny. But, ironically, quantum mechanics has to work on a huge scale. So macroscopic, and not just microscopic, objects follow quantum mechanics. Actually, they do to some extent. “I exist therefore I am, but do you think you are what you are?” It was crossing the borderline of science and trespassing onto the territory of philosophy.

We both agreed that the role of the ‘observer’ regarding the ‘observed’ is not yet really understood at all. It is such a relief that we do know that we exist and we also know that black holes will not be produced in the Large Hadron Collider at Geneva.

Isaac Newton and Albert Einstein changed the whole world — or shall we say the universe — with their daring discoveries. Penrose is on the threshold of that, creating an audacious idea which may indeed change the worldview once more.