The Big Bang or an Infinite Cycle?
Scientists are messing with our poor simple minds again! Young, hip (relatively speaking) physicists are making a case that the universe may not have started with the “big bang” at all. They believe that the universe may undergo endless cycles of evolution in infinite space and time.
One hotly disputed theory is that there is no beginning, and no end because space and time have always existed in an endless cycle of expansion and rebirth. They point out that the expansion of the universe is accelerating, as astronomers have recently observed and that after trillions of years, expansion eventually stalls, new matter and radiation is created, and then the cycle begins yet again.
Why does any of this matter? One reason is that if we’re approaching one of the most basic questions of reality and existence from the wrong angle, we’re only going to get so far before we hit a proverbial wall.
"I think the challenge we're raising is that the usual picture of the Big Bang is based on an assumption which is that time, space, matter, energy, everything began at the Big Bang," says Neil Turok, professor of mathematical physics at Cambridge University. "And that assumption was made in the 60s when people got the first strong observational evidence that the Big Bang happened. But it's really just an assumption and our point of view has come out of new development in physics which are enabling us to describe the behavior of matter in very extreme conditions such as were present around the Bang. And what we're seeing is that the Big Bang doesn't have to be the beginning of time. It's perfectly possible that the Big Bang was just a violent event in a pre-existing universe,"
Many well-respected scientists believe that newly developed theories offer a bigger picture of reality—one that may be difficult for us to wrap our minds around, but not impossible. Perhaps the Big Bang was just a big bang, and not the beginning of existence. Just like most rabble-rousing ideas, these theories may take some time before more scientists “warm” up to them. Take global warming for example. Really it wasn’t that long ago the majority of scientists didn’t think theories about “global warming” would amount to much. Now the very few who still think it’s not happening are ridiculed as foolish. In other words, when it comes to science things are sometimes scoffed at before they are whole-heartedly embraced.
One problem is that new theories can be difficult to grasp if you are not well versed in the intricate details of exotic and experimental physics, like string theory. Your average person doesn’t “get it”, but neither do many astronomers and scientists. Turok attempts to explain, but even his dumbed-down version might make your head explode.
"This picture emerged out of a new understanding of the laws of physics which is called M Theory…according to this picture, the world may be comprised of two objects called branes, short for membranes. ... And so the picture is that we live in a three-dimensional world, just the height, width and length of ordinary space but separated from our dimensions by a very tiny distance are another three-dimensions and so the whole world is four-dimensional in this picture and these two sets of dimensions can actually collide with each-other. What we discovered is, if they do collide, then something like a Big Bang happens but the density of matter and the size of the universe is not zero at that point. It's as if two objects clash together and this clash is what releases radiation which fills space.”
In fact, there are several valid theories of how the universe did or didn’t begin, but for the purposes of modern science it is easier to pick one that seems to work and hang onto it. However, some revolutionaries say that just because something seems to work for measurement purposes, doesn’t make it completely true. Alan Guth, professor of physics at the Massachusetts Institute of Technology (MIT) explains how the Big Bang theory may just be one piece of the puzzle that fits into another theory, known as inflationary theory.
"In the what I would regard as the conventional version of the inflationary theory, the Big Bang was also not in that theory the origin of everything but rather one had a very long period of this exponential expansion of the universe, which is what inflation means, and, at different points, different pieces of this inflating universe had stopped inflating and become what I sometimes call pocket universes,"
"... What we call the Big Bang was almost certainly not the actual origin of time in either of the theories that we're talking about. ... The main difference I think [between the inflationary theory and Neil and Paul's theory outlined in the book Endless Universe: Beyond the Big Bang] is the answer to the question of what is it that made the universe large and smooth everything out. ... The inflationary version of cosmology is not cyclic. ... It goes on literally forever with new universes being created in other places. The inflationary prediction is that our region of the universe would become ultimately empty and void but meanwhile other universes would spout out in other places in this multiverse," says Guth.
Janna Levin, professor of physics and astronomy at Barnard College, says, "There's a little more resistance to the cyclic model but maybe that's because of the successes so far of inflation. Yet, we do know that there are fundamental things about the early universe and the Big Bang that we don't understand. ... String theory or M theory or these other models of fundamental physics are going to be important in terms of formulating that early universe picture but they're not complete yet."
As Levin says, there are still unanswered questions. Newer theories may hold some of the answers. The beautiful thing about science is that it can be tried, tested, proven and disproved. We don’t have to keep on believing the same thing for the sake of tradition. Whether or not these scientists are someday “proven” to be correct or wrong in their theories, they still provide a valuable reminder that questioning IS the basis for new discovery and for Science itself.
Posted by Rebecca Sato
The Big Bang or an Infinite Cycle?
http://www.onpointradio.org/shows/20...531_b_main.asp
Source: NPR
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Universe in 'endless cycle'
The current expansion will go on for trillions of years
Get your head around this: the Universe had no beginning and it will have no end.Two scientists have put forward a new model to explain how the cosmos is and where it might be going.
They say it is necessary to take account of startling recent discoveries such as the observation that everything in the Universe is moving apart at an accelerating rate.
Paul Steinhardt and Neil Turok propose that the cosmos goes through an endless cycle - of Big Bang, expansion and stagnation - driven by an as yet unexplained "dark energy".
They have put forward their views in the journal Science.
Star surprise
The current model of the Universe starts with a Big Bang, a mighty explosion of space, matter and time about 14 billion years ago.
What we're proposing in this new picture is that the Big Bang is not a beginning of time but really just the latest in an infinite series of cycles
Paul SteinhardtThis model accounts for several important features we see in the Universe - such as why everything looks the same in all directions and the fact that the cosmos appears "flat" (parallel lines would never meet however long).But the model has several shortcomings, Steinhardt and Turok say.
It cannot tell us what happened before the Big Bang or explain the eventual fate of the Universe. Will it expand forever or stop and contract?
Problems with these futures became apparent in 1998, when studies of distant, exploding stars showed the Universe was expanding at an accelerating rate. It was a big surprise for some astronomers who thought everything might eventually come back together in a "Big Crunch".
Empty and flat
The apparent acceleration has since been checked and shown to be real.
It led cosmologists to revive an old idea that some "dark energy" is at work in the cosmos, pushing everything apart.
Steinhardt and Turok put this energy - a scalar field as they mathematically describe it - right at the centre of their new model.
They think the dark energy drives a cycle of activity that includes a big bang and a subsequent period of expansion that leaves the Universe smooth, empty and flat.
"The scalar field changes its character over time," Paul Steinhardt told the BBC. "Finally, the field begins to build up energy to a point where it suddenly becomes unstable and bursts into matter and radiation, filling the Universe, and driving the next period of expansion."
'Hardest science'
He added: "In the standard picture, it's presumed that the Big Bang is actually a beginning of space and time; that there was nothingness, and then suddenly out of nothingness there sprang space, time, matter, radiation, etcetera.
The history of cosmology is the history of us being completely wrong
Cosmology writer Marcus Chown"What we're proposing in this new picture is that the Big Bang is not a beginning of time but really just the latest in an infinite series of cycles, in which the Universe has gone through periods of heating, expanding, cooling, stagnating, emptying, and then re-expanding again."Steinhardt and Turok have discussed their ideas with peers and have received a positive, but "cautious", response. "The ultimate arbiter will be Nature," they write in the journal Science.
"Measurements of gravitational waves and the properties of dark energy can provide decisive ways to discriminate between the two pictures observationally."
Cosmology writer Marcus Chown concedes it will be extremely difficult to finally prove any model of the Universe.
"The history of cosmology is the history of us being completely wrong," he told the BBC. "I mean, cosmology is the hardest of all sciences; we sit on this tiny planet in the middle of this vast Universe, we can't go anywhere and do any experiments - all we can do is pick up the light that happens to fall on us and deduce some things about the Universe."
Paul Steinhardt is at Princeton University, US, and Neil Turok is at Cambridge University, UK.
BBC News | SCI/TECH | Universe in 'endless cycle'
