From Eternity to here- Sean Carroll

 

An extremely educative and entertaining read. This book by Sean Carroll touches upon all those big impressive questions that has wracked mankind, or possibly any sentient being, anywhere in the Universe. What is Time? What is Space? Why do we remember only our past and not the future? Can we travel through Time? What is going to happen to the Universe? Will it go on forever? Or is it all going to end up in one Big Crunch someday?

The author makes it clear that of course , he doesn’t have the answers. No one does probably. But that doesn’t stop Carroll from taking us on an entertaining ride, and in a fairly easy to understand manner attempts to answer these tough questions based on the scientific knowledge and evidence available as on date.

Time seems to be special. There appears to be a beginning of Time wrought upon us supposedly by the Big Bang, some 13.8 Billion years ago. Space? Well, Space is all the same for the Universe. Up, down, left, right… there is no difference. And no, the Big Bang did not occur at any particular point in Space, but yeah, it did occur at a particular point in Time, apparently.

Time, of course, is special. There is a Past Time and there will be a Future Time. And how does the Universe distinguish the Past Time from Future Time? Entropy is the answer. The distinguishing feature of Time is that at any point in the past, the Universe was in a state of lower Entropy and in the future it will be in a state of higher Entropy. Entropy, is loosely defined as the state of disorder in a system.  And the Universe is ultimately headed there- to a state of increasing disorder and chaos. All these very orderly Planets, Stars, Galaxies, even Black Holes…(and yeah, life itself), all will dissipate into  a very disorderly, fundamental particle state, billions of years into the future. Yes, even Black holes too, thanks to the dissipation caused by the Hawkings radiation. So the final pretty picture of the Universe is of isolation and desolation essentially.

So the question arises- if the natural order of the Universe is to be in a high Entropy state, how come we are in this seemingly low Entropy environment? And able to bask in the sunset, admire the birds and the flowers, marvel at the Swirling Milky Way? That is the question that no one is able to give a clear answer to. Why was the Early Universe in such a Low Entropy State? Tempting to think in Anthropic Terms, of course. The Universe exists for us, Creationism etc. But, of course, who has time for such fairy tales?

An interesting theory cited in the book is a Boltzmann hypothesis of the observable Universe being a fluctuation on the entropy equilibrium scale. A box containing gas molecules reaches an equilibrium state of high Entropy, with all the gas molecules dissipated randomly all around the box. But Boltzmann says that the high Entropy state of these Gas molecules are not always constant. There will be  minor fluctuations all the time, wherein there would be a temporary dip into a lower entropy state, before the Law asserts itself and the gas molecules re-aligns themselves into its default high equilibrium state- The state of max entropy. What if, asks Boltzmann, if this observable Universe that we are in, is in a state of one of those random fluctuations, with the dip in entropy now being in the process of being corrected, with the Universe moving to its goal of maximum entropy state?

To quote from the book:

“Ah, says Boltzmann, you have to take a wider view. What we've shown …. are tiny fluctuations in Entropy over a relatively short period of time. When we're talking about the universe, we are obviously imagining a huge fluctuation in entropy that is very rare and takes an extremely long time to play itself out. …. the entropy of our local, observe part of Universe …. where a fluctuation has occurred and is in the process of bouncing back to equilibrium. If the entire history of the known universe were to fit there, we would indeed see the Second Law at work over our lifetimes, while over ultra-long times the entropy is simply fluctuating near its maximum value.”

 

Its just a theory, of course. Just idle drinking session chatter. No one knows really.

 There are so many great passages in the book. I will just quote a couple that has stayed with me. One is by Schrodinger on what life is:

 What is the characteristic feature of life? When is a piece of matter said to be alive? When it goes on 'doing something, exchanging material with its environment, and so forth, and that for a much longer period than we would expect an inanimate piece of matter to keep going' under similar circumstances.

Schrodinger is making the point that nonliving physical objects tend to wind down and come to rest. A rock may roll down a hill during an avalanche.  But before too long it will reach the bottom, dissipate energy through the creation of noise and heat, and come to a complete halt. For living organisms, this process of coming to rest can take much longer.  And that, suggests Schrödinger, is the essence of life- staving off the natural tendency toward equilibrium with one's surroundings- why the goldfish is still swimming long after the ice cube would have melted.

So life is, as one always suspected, a struggle against the natural order of the Universe.

And of course, this one by Carroll  is quite swanky and can easily be in those quotable quotes area:

“That's okay. We find ourselves, not as a central player in the life of the cosmos. But as a tiny epiphenomenon, flourishing for a brief moment as we ride a wave of increasing entropy from the Big Bang to the quiet emptiness of the future universe. Purpose and meaning are not to be found in the laws of nature, or in the plans of any external agent who made things that way; it is our job to create them. One of those purposes-among many-stems from our urge to explain the world around us the best we can. If our lives are brief and undirected, at least we can take pride in our mutual courage as we struggle to understand things much greater than ourselves.”

 But of course, as Carroll himself would agree, Purpose and pride etc are all Anthropic principles. The Universe simply does not care one way or the other. Period.