I found this amazing site called The Edge! The site description goes:
To arrive at the edge of the world’s knowledge, seek out the most complex and sophisticated minds, put them in a room together, and have them ask each other the questions they are asking themselves.
It suffices to say that this will eat up countless hours by the computer, ’cause I’m gonna be reading every word on this site. Here’s a post that immediately caught my attention. It’s about the idea of a cyclical universe, something that figures heavy into my upcoming webisode series Ouroboros.
[NEIL TUROK:] For the last ten years I have mainly been working on the question of how the universe began — or didn’t begin. What happened at the Big Bang? To me this seems like one of the most fundamental questions in science, because everything we know of emerged from the Big Bang. Whether it’s particles or planets or stars or, ultimately, even life itself.
In recent years, the search for the fundamental laws of nature has forced us to think about the Big Bang much more deeply. According to our best theories — string theory and M theory — all of the details of the laws of physics are actually determined by the structure of the universe; specifically, by the arrangement of tiny, curled-up extra dimensions of space. This is a very beautiful picture: particle physics itself is now just another aspect of cosmology. But if you want to understand why the extra dimensions are arranged as they are, you have to understand the Big Bang because that’s where everything came from.
Somehow, until quite recently, fundamental physics had gotten along without really tackling that problem. Even back in the 1920’s, Einstein, Friedmann and Lemaitre — the founders of modern cosmology — realized there was a singularity at the Big Bang. That somehow, when you trace the universe back, everything went wrong about 14 billion years ago. By go wrong, I mean all the laws of physics break down: they give infinities and meaningless results. Einstein himself didn’t interpret this as the beginning of time; he just said, well, my theory fails. Most theories fail in some regime, and then you need a better theory. Isaac Newton’s theory fails when particles go very fast; it fails to describe that. You need relativity. Likewise, Einstein said, we need a better theory of gravity than mine.
But in the 1960’s, when the observational evidence for the Big Bang became very strong, physicists somehow leapt to the conclusion that it must have been the beginning of time. I am not sure why they did so, but perhaps it was due to Fred Hoyle — the main proponent of the rival steady-state theory — who seems to have successfully ridiculed the Big Bang theory by saying it did not make sense because it implied a beginning of time and that sounded nonsensical.
Then the Big Bang was confirmed by observation. And I think everyone just bought Hoyle’s argument and said, oh well, the Big Bang is true, okay, so time must have begun. So we slipped into this way of thinking: that somehow time began and that the process, or event, whereby it began is not describable by physics. That’s very sad. Everything we see around us rests completely on that event, and yet that is the event we can’t describe. That’s basically where things stood in cosmology, and people just worried about other questions for the next 20 years.
And then in the 1980s, there was a merging of particle physics and cosmology, when the theory of inflation was invented. Inflationary theory also didn’t deal with the beginning of the universe, but it took us back further towards it. People said, let’s just assume the universe began, somehow. But, we’re going to assume that when it began, it was full of a weird sort of energy called inflationary energy. This energy is repulsive — its gravitational field is not attractive, like ordinary matter — and the main property of that energy is that it causes the universe to expand, hugely fast. Literally like dynamite, it blows up the universe.
This inflationary theory became very popular. It made some predictions about the universe, and recent observations are very much in line with them. The type of predictions it made are rather simple and qualitative descriptions of certain features of the universe: it’s very smooth and flat on large scales; and it has some density variations, of a very simple character. Inflationary theory predicts that the density variations are like random noise — something like the ripples on the surface of the sea — and fractional variation in the density is roughly the same on all length scales. And these predictions of inflation have been broadly confirmed by observation. So people have become very attracted to inflation and many people think it’s correct. But inflationary theory never really dealt with the beginning of the universe. We just had to assume the universe started out full of inflationary energy. That was never explained.
Does Objective Reality Exist, or is the Universe a Phantasm?
In 1982 a remarkable event took place. At the University of Paris a research team led by physicist Alain Aspect performed what may turn out to be one of the most important experiments of the 20th century.You did not hear about it on the evening news. In fact, unless you are in the habit of reading scientific journals you probably have never even heard Aspect’s name, though there are some who believe his discovery may change the face of science.
Aspect and his team discovered that under certain circumstances subatomic particles such as electrons are able to instantaneously communicate with each other regardless of the distance separating them. It doesn’t matter whether they are 10 feet or 10 billion miles apart. Somehow each particle always seems to know what the other is doing. The problem with this feat is that it violates Einstein’s long-held tenet that no communication can travel faster than the speed of light. Since traveling faster than the speed of light is tantamount to breaking the time barrier, this daunting prospect has caused some physicists to try to come up with elaborate ways to explain away Aspect’s findings. But it has inspired others to offer even more radical explanations.
University of London physicist David Bohm, for example, believes Aspect’s findings imply that objective reality does not exist, that despite its apparent solidity the universe is at heart a phantasm, a gigantic and splendidly detailed hologram.
To understand why Bohm makes this startling assertion, one must first understand a little about holograms. A hologram is a three- dimensional photograph made with the aid of a laser. To make a hologram, the object to be photographed is first bathed in the light of a laser beam. Then a second laser beam is bounced off the reflected light of the first and the resulting interference pattern (the area where the two laser beams commingle) is captured on film. When the film is developed, it looks like a meaningless swirl of light and dark lines. But as soon as the developed film is illuminated by another laser beam, a three-dimensional image of the original object appears.
Uh-oh. Did someone just discover the inherent paradox of human consciousness within the context of limited lifespan and the physical laws of the universe? Is someone going to be our next Sartre? This 6-year-old existential poet is Julian, the son of a redditor, and soon to be among the ranks of Camus, Pessoa, et al.
Via TED Lectures
Backed by stunning illustrations, David Christian narrates a complete history of the universe, from the Big Bang to the Internet, in a riveting 18 minutes. This is “Big History”: an enlightening, wide-angle look at complexity, life and humanity, set against our slim share of the cosmic timeline.
About David Christian:
David Christian teaches an ambitious world history course that tells the tale of the entire universe — from the Big Bang 13 billion years ago to present day. Full bio and more links
The current cosmological census is that the universe began 13.7 billion years ago with the Big Bang. But a legendary physicist says he’s found the first evidence of an eternal, cyclic cosmos.
The Big Bang model holds that everything that now comprises the universe was once concentrated in a single point of near-infinite density. Before this singularity exploded and the universe began, there was absolutely nothing – indeed, it’s not clear whether one can even use the term “before” in reference to a pre-Big-Bang cosmos, as time itself may not have existed yet. In the current model, the universe began with the Big Bang, underwent cosmic inflation for a fraction of a second, then settled into the much more gradual expansion that is still going on, and likely will end with the universe as an infinitely expanded, featureless cosmos.
Sir Roger Penrose, one of the most renowned physicists of the last fifty years, takes issue with this view. He points out that the universe was apparently born in a very low state of entropy, meaning a very high degree of order initially existed, and this is what made the complex matter we see all around us (and are composed of) possible in the first place. His objection is that the Big Bang model can’t explain why such a low entropy state existed, and he believes he has a solution – that the universe is just one of many in a cyclical chain, with each Big Bang starting up a new universe in place of the one before.
How does this help? Well, Penrose posits the end of each universe will involve a return to low entropy. This is because black holes suck in all the matter, energy, and information they encounter, which works to remove entropy from our universe. (Where that entropy might go is another question entirely.) The universe’s continued expansion into eventual nothingness causes the black holes themselves to evaporate, which ultimately leaves the universe in a highly ordered state once again, ready to contract into another singularity and set off the next Big Bang.
As alternative theories go, it’s not without its merits, but there’s no evidence to support it…until now. He says he’s found evidence for his ideas in the cosmic microwave background, the microwave radiation that permeates the universe and was thought to have formed 300,000 years after the Big Bang, providing a record of the universe at that far distant time. Penrose and his colleague Vahe Gurzadyan have discovered clear concentric circles within the data, which suggests regions of the radiation have much smaller temperature ranges than elsewhere.
So what does that mean? Penrose believes these circles are windows into the previous universe, spherical ripples left behind by the gravitational effects of colliding black holes in the previous universe. He also says these circles don’t work well at all in the current inflationary model, which holds all temperature variations in the CMB should be truly random.
Here’s where the fun begins. If the circles are really there and are really doing what Penrose says they’re doing, then he’s managed to overthrow the standard inflationary model. But there’s a long way to go between where we are now and that point, assuming it ever happens.