Showing posts with label cosmology. Show all posts
Showing posts with label cosmology. Show all posts

Thursday, November 29, 2007

Sunday, April 08, 2007

Universes Within Universes

I'm nearing the end of my Cosmos adventure and I again recommend getting hold of a copy, if you've never seen it. Here are a couple of very interesting extracts from the book of the series:

...very likely, the universe has been expanding since the Big Bang, but it is by no means clear that it will continue to expand forever. The expansion may gradually slow, stop and reverse itself. If there is less than a certain critical amount of matter in the universe, the gravitation of the receding galaxies will be insufficient to stop the expansion, and the universe will run away forever. But if there is more matter than we can see - hidden away in black holes, say, or in hot but invisible gas between the galaxies - then the universe will hold together gravitationally and partake of a very Indian succession of cycles, expansion followed by contraction, universe upon universe, Cosmos without end. If we live in such an oscillating universe, then the Big Bang is not the creation of the Cosmos but merely the end of the previous cycle, the destruction of the last incarnation of the Cosmos.

Neither of these modern cosmologies may be altogether to our liking. In one, the universe is created, somehow, ten or twenty billion years ago and expands forever, the galaxies mutually receding until the last one disappears over our cosmic horizon. Then the galactic astronomers are out of business, the stars cool and die, matter itself decays and the universe becomes a thin cold haze of elementary particles. In the other, the oscillating universe, the Cosmos has no beginning and no end, and we are in the midst of an infinite cycle of cosmic deaths and rebirths with no information trickling through the cusps of the oscillation. Nothing of the galaxies, stars, planets, life forms or civilizations evolved in the previous incarnation of the universe oozes into the cusp, flutters past the Big Bang, to be known in our present universe. The fate of the universe in either cosmology may seem a little depressing, but we may take solace in the time scales involved. These events will occupy tens of billions of years, or more. Human beings and our descendants, whoever they might be, can accomplish a great deal in tens of billions of years, before the Cosmos dies.
And slightly further on:
There is an idea - strange, haunting, evocative - one of the most exquisite conjectures in science or religion. It is entirely undemonstrated; it may never be proved.

But it stirs the blood. There is, we are told, an infinite hierarchy of universes, so that an elementary particle, such as an electron, in our universe would, if penetrated, reveal itself to be an entire closed universe. Within it, organized into the local equivalent of galaxies and smaller structures, are an immense number of other, much tinier elementary particles, which are themselves universe at the next level, and so on forever - an infinite downward regression, universes within universes, endlessly. And upward as well. Our familiar universe of galaxies and stars, planets and people, would be a single elementary particle in the next universe up, the first step of another infinite regress.
Much as I love Carl, isn't that just mind-bogglingly absurd?

Saturday, April 07, 2007

Cosmos


One of the reasons I've been feeling uninspired this week is because I've been watching Carl Sagan's amazing 13 episode documentary, Cosmos. It really is a fantastic series and I was surprised to learn quite a lot of new information from it (despite being nearly thirty years old).

So why do I find myself uninspired, by one of the most inspiring of our species? Because Carl is just so giddy about it all. He finds wonder and beauty, where I only see a huge, old universe that cares not for our affairs.

I was trying to understand Carl's optimism and found this extract from a biography:
All his life, Carl Sagan was troubled by grand dichotomies—between reason and irrationalism, between wonder and skepticism. The dichotomies clashed within him. He yearned to believe in marvelous things—in flying saucers, in Martians, in glistening civilizations across the Milky Way. Yet reason usually brought him back to Earth. Usually; not always. A visionary dreams of a better world than this one. He refuses to think that modern society and its trappings—money, marriage, children, a nine-to-five career, and obeisance to a waving flag and an inscrutable God—are all there is. Sagan was blinded, but not by these. He was blinded by the sheer glory of the new cosmos that was unveiled by science during the first two decades of his life. This cosmos was an ever-expanding, unbounded wonderland of billions of galaxies. And across the light-years, Sagan dreamed, random molecular jigglings had perhaps spawned creeping, crawling, thinking creatures on alien landscapes bathed in the glow of alien suns.
And I found this sentence from a NY Times review of two biographies of Carl:
Both books delight in the discovery that Sagan smoked bales of marijuana and attributed to the weed vital moments of intellectual inspiration.
So Carl Sagan was another who wanted to get high and sail the stars. In Cosmos he is a happy chappy dreamer which is all well and good, but even Hunter S. Thompson, blew out his brains in the end:
"No More Games. No More Bombs. No More Walking. No More Fun. No More Swimming. 67. That is 17 years past 50. 17 more than I needed or wanted. Boring. I am always bitchy. No Fun — for anybody. 67. You are getting Greedy. Act your old age. Relax — This won't hurt"

Friday, March 09, 2007

Weinberg's Three Minutes

From Steven Weinberg's, 'The First Three Minutes':

However all these (cosmological) problems may be resolved, and whichever cosmological model proves correct, there is not much of comfort in any of this. It is almost irresistible for humans to believe that we have some special relation to the universe, that human life is not just a more-or-less farcical outcome of a chain of accidents reaching back to the first three minutes, but that we were somehow built in from the beginning.

As I write this I happen to be in an airplane at 30,000 feet, flying over Wyoming en route home from San Francisco to Boston. Below, the earth looks very soft and comfortable--fluffy clouds here and there, now turning pink as the sun sets, roads stretching straight across the country from one town to another. It is very hard to realize that this all is just a tiny part of an overwhelming hostile universe. It is even harder to realize that this present universe has evolved from an unspeakably unfamiliar early condition, and faces a future extinction of endless cold or intolerable heat. The more the universe seems comprehensible, the more it also seems pointless.

But if there is no solace in the fruits of our research, there is at least some consolation in the research itself. Men and women are not content to comfort themselves with tales of gods and giants, or to confine their thoughts to the daily affairs of life; they also build telescopes and satellites and accelerators, and sit at their desks for endless hours working out the meaning of the data they gather. The effort to understand the universe is one of the very few things that lifts human life a little above the level of farce, and gives it some of the grace of tragedy.

Monday, December 04, 2006

Truth in an Encyclopedia

Last year I got a chance to read through the Gale Encyclopedia of Science and Religion. I was shocked to discover a very interesting paragraph under the heading Eschatology (the study of last things):

Biology, paleontology, geology, and astronomy help one appreciate the transience and fragility of all that exists, even though nature continually brings new things and new life out of dissolution and death. No individual entity or species continues forever. Cosmology assures us that the observable universe itself will eventually become sterile and evanesce as it expands forever, undergoing heat death (p.300)
Of course we don't yet conclusively know which way the universe is actually going to die (although it really is either the big crunch or the big freeze), but even if you don't want to think that far ahead, just remember that your own personal existence is just as fragile as the rest of the universe.