This is a very interesting video that I want to finish watching.
Wednesday, April 30, 2008
Friday, April 11, 2008
Did pre-big bang universe leave its mark on the sky? - space - 10 April 2008 - New Scientist Space
This article might give us a way to check for a pre-big bang universe.
In cosmological models based on a theory called loop quantum gravity, our universe has a parent. Loop quantum gravity attempts to meld relativity with quantum mechanics by describing space-time as a constantly rearranging fabric of interconnections. On the smallest scales, around 10-35 meters, that fabric is a tangled mess, but on much larger scales the space and time of our universe look smooth.
The theory predicts that when this fabric is scrunched up, it becomes bouncy. So if the universe before ours was contracting, it would have reached a point of maximum density and then bounced out again in our big bang.
So what would this predecessor have been like? To find out, Parampreet Singh of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, and Alejandro Corichi of the National Autonomous University of Mexico, Morelia, applied the equations of loop quantum gravity to a highly simplified model of the universe. They found that the properties of space, such as the quantity of matter and energy it contains, hardly change when the universe goes through the big bounce. "For the simple model considered, the universe is almost exactly the same on other side," says Singh.
It raises the possibility that we could see an imprint of the universe before ours. Singh suggests that the seeds of large-scale structures in our universe, such as superclusters of galaxies, would have been present on the pre-big-bang side. The pattern of those seeds might be preserved in the cosmic microwave background radiation - the relic radiation left behind by the big bang. "If this conclusion holds true, then it is possible that we are going to see signatures of the pre-big-bang universe," says Singh.
Did pre-big bang universe leave its mark on the sky? - space - 10 April 2008 - New Scientist Space
Technorati Tags: loop quantum gravity
Thursday, April 10, 2008
Ask Michio: If parallel universes exist, can they collide? - Michio Kaku
I have discovered Michio Kaku. He is a great explainer of science to the layman. Try the explanation below to see if it doesn't explain cosmology better than you knew it before.
This is the first time I have heard about the Big Splat. Michio Kaku's link is
mkaku.org
If parallel universes exist, can they collide?
Matthew
EnglandMichio: Probably. The latest cosmological data comes from the WMAP satellite currently orbiting the earth. The data is consistent with “inflation,” i.e. the idea that the universe began in a super turbo-charged expansion at the instant of the big bang. However, inflation is also a quantum theory, i.e. there is a finite probability that if inflation happened once, it can happen again, and again. In fact, big bangs may be happening all the time, even as you read this sentence. There may be a continual creation of universes.
In other words, our universe is probably a bubble of some sort which is expanding. But inflation theory seems to indicate that we may not be the only bubble/universe. Think of a bubble bath, in which there are innumerable soap bubbles floating, sometimes colliding, sometimes breaking in half, sometimes popping in and out of existence. This is the “multiverse” picture which seems to be emerging from inflation theory.
Inflation theory, however, cannot explain the dynamics of these bubble/universes. Inflation simply states that such a turbo-charged expansion took place, but inflation does not explain why inflation took place in the first place, or what drives it. For that, we need a higher theory, such as string theory (or its latest version, M-theory, where M stands for membrane).
In M-theory, there are innumerable membranes floating in a much larger arena (11 dimensional hyperspace). We live on the skin of one such bubble which lives in 3 dimensional space. However, there may be other “branes” floating in 11 dimensional hyperspace. The physicists at Princeton calculated what would happen if two such branes collided. Much to their surprise, they found that the two branes would merge and create a shock wave. By analyzing this shock wave, they found that it resembled the big bang itself. In fact, they were led to believe that this WAS the big bang. This theory is now called the Big Splat theory, and is one of the serious candidates for the underlying big bang theory.
Ask Michio: If parallel universes exist, can they collide? - Michio Kaku
Subscribe to:
Posts (Atom)