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[24. Apr 2005|15:38]
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astronomija

[laboratorija]
'Brane-Storm' Challenges Part of Big Bang Theory

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.)

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 told SPACE.com. "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."

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