Faster than you can say "Ekpyrotic Universe," a movement has taken hold -- albeit like fingers on a ledge of eternal skepticism -- that would blow one of the basic tenets of the Big Bang to smithereens.
Think parallel branes and five dimensions. Science never sounded so cool.
The new idea would not replace the Big Bang, which has for more than 50 years dominated cosmologists' thinking over how the universe began and evolved. But instead of a universe springing forth in a violent instant from an infinitely small point of infinite density, the new view argues that our universe was created when two parallel "membranes" collided cataclysmically after evolving slowly in five-dimensional space over an exceedingly long period of time.
These membranes, or "branes" as theorists call them, would have floated like sheets of paper through a fifth dimension that even scientists admit they find hard to picture intuitively. (Our conventional view of 3-D physical space, along with time, make up the four known dimensions.)
"It's almost crazy enough to be correct."
-- Michael Turner, University of Chicago cosmologist
The idea, put forth earlier this month at a Space Telescope Science Institute meeting in Baltimore, is based on other theories about possible multiple dimensions that are growing in acceptance. It was developed by Neil Turok of Cambridge University, Burt Ovrut of the University of Pennsylvania, and Paul Steinhardt and Justin Khoury of Princeton University.
"The [Ekpyrotic] scenario is that our current universe is [a] four-dimensional membrane embedded in a five-dimensional 'bulk' space, something like a sheet of paper in ordinary three-dimensional space," Turok said. "The idea then is that another membrane collided with ours, releasing energy and heat and leading to the expansion of our universe."
Crazy, but viable
"It's almost crazy enough to be correct," says Michael Turner, a longtime University of Chicago cosmologist who is familiar with the theory. He added that "when you're trying to crack a really hard problem, you need a crazy idea."
Turner said astronomers have reacted with great excitement to the new theory, in part because the idea of alternate dimensions is largely new to most of them. Cosmologists tend to welcome the idea as a healthy potential alternative to certain aspects of the Big Bang, but are cautious about the theory's prospects.
Mario Livio, who heads up the science division of the Space Telescope Science Institute, said it's way too early to predict whether the theory will withstand scrutiny by other researchers. But he called the concept very important and exciting: "We're talking about a new idea about the origin of our universe."
The Ekpyrotic Universe draws its name from the ancient Greek word ekpyrosis, meaning "conflagration" (disastrous fire or conflict). According to an ancient cosmological model with this name, the universe was created in a sudden burst of fire. The modern-day theorists say this ancient idea is not unlike the collision proposed in the new model.
While the new theory is full of complex math and obscure concepts, it is a somewhat soothing idea for anyone who has ever wondered what the heck lies beyond our universe. C'mon, admit it -- at least once you thought about the edge of the universe and mumbled, prayed, dreamed or asked: "But what is beyond that."
So, what is beyond the edge of the universe?
The fifth dimension is what is beyond the edge of the universe, say the creators of the idea. Though they argue that there is in fact no edge.
"There is only one universe," Ovrut said in a telephone interview. "It does not have a boundary. It's just one large extended brane that has been hit, heated up and is expanding."
The mind-bending concept does not involve multiple or parallel universes, as have been suggested by other researchers.
Instead, Ovrut explains, the fifth dimension is all there, is out there, and embedded in it are multiple branes. Each end of the fifth dimension is bounded by an infinite brane. Our visible universe is one of those, and before the collision it may or may not have contained normal matter. At the other end of the fifth dimension is a brane with physics unlike ours. The branes in between, while they may contain matter, are not universes, and they do not resemble the brane we inhabit.
There is no reason to assume, given this conceptual framework, that there are any other universes out there, Ovrut said.
Alternative to explain inflation
A paper on the concept has been submitted to the journal Physical Review D. While the paper has not yet been accepted for publication, surprised and thrilled physicists who are familiar with it are describing the Ekpyrotic Universe as exciting, plausible and a worthy competitor to a problematic aspect of the Big Bang known as inflation.
Inflation attempts to account for the seeming uniformity of the universe. Look in any direction of the sky, and there are features in the universe -- galaxies and clusters of galaxies -- that very much resemble those in any other direction. The theory of inflation accounts for this by putting all matter in one spot at the beginning, then shooting it outward faster than the speed of light in a period of inflation whereby everything developed under similar rules regardless of where it was headed.
Ovrut said that in modeling a collision of branes, his group found that the result would be a universe that fits neatly with predictions of the Big Bang. It produces similar temperatures and causes the resulting universe to expand, for example, and creates matter with the same uniformity predicted by inflation.
"We are not attacking the theory of inflation," Ovrut said. "We're just presenting an alternative."
Turner, the University of Chicago cosmologist, said inflation theory has been so successful that it has killed all competing theories. But inflation doesn't address the idea that there might be other dimensions. Interest in this wild notion has grown among cosmologists in recent years.
In textbooks a century from now, Turner believes there will be one of the following two paragraphs:
"A hundred years ago, people were so desperate to try to understand how to put it all together, they invented additional spatial dimensions. What were they smoking?" Or: "A hundred years ago, people were so provincial that in spite of much evidence that there should be extra dimensions they refused to accept it."
http://www.space.com/scienceastronomy/astronomy/bigbang_alternative_010413-1.html
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