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View Full Version : What Happened Before the Big Bang?



ckb2001
07-01-2007, 02:32 PM
So, there has been this persistent question in physics whether the Big Bang was really the "beginning" or whether a Big Crunch preceded it (kind of the opposite of a Big Bang). So, you can call that a "Big Bounce" if it's true.

It seems like the first mathematical model allowing us to describe what could have occurred before the Big Bang has been developed (where you can see the influence of all the free parameters):
http://www.physorg.com/news102516861.html

"The model's equations require parameters that describe the state of our current universe accurately so that scientists then can use the model to travel backward in time, mathematically "un-evolving" the universe to reveal its state at earlier times. The model's equations also contain some "free" parameters that are not yet known precisely but are nevertheless necessary to describe certain properties."

"A problem with the earlier numerical model is you don't see so clearly what the free parameters really are and what their influence is," Bojowald said. "This mathematical model gives you an improved expression that contains all the free parameters and you can immediately see the influence of each one," he explained. "After the equations were solved, it was rather immediate to reach conclusions from the results."
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PhinPhan1227
07-02-2007, 11:47 AM
I know scientists think they will eventually be able to get to the Bang itself, but they don't see any way of ever actually seeing what led up to it do they?

ckb2001
07-02-2007, 04:03 PM
I know scientists think they will eventually be able to get to the Bang itself, but they don't see any way of ever actually seeing what led up to it do they?

You hit it on the mark. This is exactly why this new theory is important. No, it doesn't mean it's more likely the Big Bang was really a Big Bounce. But, it's the first time a theory allows us to deduce properties about what happened before the Big Bang IF it really is a Big Bounce. Anyway, keep in mind this is just mostly a mathematical exercise, but that usually comes first before physicists figure out how one can test such claims.

PhinPhan1227
07-03-2007, 03:39 PM
You hit it on the mark. This is exactly why this new theory is important. No, it doesn't mean it's more likely the Big Bang was really a Big Bounce. But, it's the first time a theory allows us to deduce properties about what happened before the Big Bang IF it really is a Big Bounce. Anyway, keep in mind this is just mostly a mathematical exercise, but that usually comes first before physicists figure out how one can test such claims.


Considering the nature of the "Big Bang" however, how will we ever be able to observe that which came before? All radiation of any sort was reorganized during the time of "compression". What possible method could be used for observation other than mere speculation?

Eshlemon
07-03-2007, 04:35 PM
The Big Diner and a Movie?

ckb2001
07-03-2007, 05:14 PM
Considering the nature of the "Big Bang" however, how will we ever be able to observe that which came before? All radiation of any sort was reorganized during the time of "compression". What possible method could be used for observation other than mere speculation?

Oh, similar question to the kinds asked about black holes in the last few decades. Initially it was thought black holes destroyed all information going into them. Recently, some physicists claim some information leakage occurs. The problem with both is there is no physics that is known to work in those extreme situations: where gravity is so strong you can't rely on quantum mechanics alone to explain what happens to subatomic particles.

So, the best answer to your question is since the physics for understanding what goes on in such extreme environments isn't even really developed, there's no reason to expect we would know how to retrieve information from what happens "on the other side" at this time.

Also, keep in mind that the Big Bang isn't considered to really be a singularity. That's what general relativity suggests. But, quantum mechanics will tell you there is an inherent uncertainty to everything, including where particles are, so if there really wasn't a singularity, then there's also no a priori reason to claim all information prior to that non-singularity was lost. You'd just have to develop the proper theory to take observations made today to deduce things about particles before they went into a "singularity".

adamprez2003
07-03-2007, 09:56 PM
Oh, similar question to the kinds asked about black holes in the last few decades. Initially it was thought black holes destroyed all information going into them. Recently, some physicists claim some information leakage occurs. The problem with both is there is no physics that is known to work in those extreme situations: where gravity is so strong you can't rely on quantum mechanics alone to explain what happens to subatomic particles.

So, the best answer to your question is since the physics for understanding what goes on in such extreme environments isn't even really developed, there's no reason to expect we would know how to retrieve information from what happens "on the other side" at this time.

Also, keep in mind that the Big Bang isn't considered to really be a singularity. That's what general relativity suggests. But, quantum mechanics will tell you there is an inherent uncertainty to everything, including where particles are, so if there really wasn't a singularity, then there's also no a priori reason to claim all information prior to that non-singularity was lost. You'd just have to develop the proper theory to take observations made today to deduce things about particles before they went into a "singularity".

It was Hawking who posited the original theory that Black Holes swallow all information. I forgot who was his main nemesis on this but I believe that Hawking was basically glorified for this theory and for thrirty years science pounded out that this was THE THEORY. This went on for thirty years or so if I'm right. Even though the string theorists and others had basically proven that this was wrong it wasn't until Hawking himself admitted he was wrong that the media caught up. Not necessarily science's fault so much as the media's ridiculous fascination with celebrity

ckb2001
07-03-2007, 10:23 PM
It was Hawking who posited the original theory that Black Holes swallow all information. I forgot who was his main nemesis on this but I believe that Hawking was basically glorified for this theory and for thrirty years science pounded out that this was THE THEORY. This went on for thirty years or so if I'm right. Even though the string theorists and others had basically proven that this was wrong it wasn't until Hawking himself admitted he was wrong that the media caught up. Not necessarily science's fault so much as the media's ridiculous fascination with celebrity

That's a bit misleading.

Hawking showed that black holes would eventually radiate away. The radiation was shown to be independent of what went into it. So, if the information from this radiation was independent of what went into it, there was no way of reconstructing what went into the black hole.

That created what was called an information loss paradox.

What Hawking was glorified for was the theory deducing black holes should radiate away, NOT creating an information loss paradox. That paradox just happened to be new information physicists came across as our understanding of Nature grew. The paradox is only recently being "resolved".

Also, no one pounded on that as "the" theory.

Furthermore, the part where Hawking was wrong on had to do with energy loss in a black hole, not information loss. The information loss part is still being studied.

Finally, having said all that, keep in mind there are literally hundreds of other theoretical physicists alive today considered on par with Hawking (and a few beyond him in terms of contribution). He's no doubt an important scientist, but he and not others of his ilk is famous primarily because of his physical condition.

If you want the name of what might be the world's top theoretical physicist (alive), that would be Ed Witten.

adamprez2003
07-03-2007, 11:07 PM
That's a bit misleading.

Hawking showed that black holes would eventually radiate away. The radiation was shown to be independent of what went into it. So, if the information from this radiation was independent of what went into it, there was no way of reconstructing what went into the black hole.

That created what was called an information loss paradox.

What Hawking was glorified for was the theory deducing black holes should radiate away, NOT creating an information loss paradox. That paradox just happened to be new information physicists came across as our understanding of Nature grew. The paradox is only recently being "resolved".

Also, no one pounded on that as "the" theory.

Furthermore, the part where Hawking was wrong on had to do with energy loss in a black hole, not information loss. The information loss part is still being studied.

Finally, having said all that, keep in mind there are literally hundreds of other theoretical physicists alive today considered on par with Hawking (and a few beyond him in terms of contribution). He's no doubt an important scientist, but he and not others of his ilk is famous primarily because of his physical condition.

If you want the name of what might be the world's top theoretical physicist (alive), that would be Ed Witten.

Thanx for the info.

PhinPhan1227
07-05-2007, 03:05 PM
Oh, similar question to the kinds asked about black holes in the last few decades. Initially it was thought black holes destroyed all information going into them. Recently, some physicists claim some information leakage occurs. The problem with both is there is no physics that is known to work in those extreme situations: where gravity is so strong you can't rely on quantum mechanics alone to explain what happens to subatomic particles.

So, the best answer to your question is since the physics for understanding what goes on in such extreme environments isn't even really developed, there's no reason to expect we would know how to retrieve information from what happens "on the other side" at this time.

Also, keep in mind that the Big Bang isn't considered to really be a singularity. That's what general relativity suggests. But, quantum mechanics will tell you there is an inherent uncertainty to everything, including where particles are, so if there really wasn't a singularity, then there's also no a priori reason to claim all information prior to that non-singularity was lost. You'd just have to develop the proper theory to take observations made today to deduce things about particles before they went into a "singularity".


But that assumes that all things before the bang were equal to those things after the bang. What if some of the constants changed?

ckb2001
07-05-2007, 04:16 PM
But that assumes that all things before the bang were equal to those things after the bang. What if some of the constants changed?

No, it doesn't assume anything of the sort. The laws of nature in this universe might just be a special case of a more general set of laws of nature. There's no a priori reason we couldn't obtain information from prior to the Big Bang if the Big Bang didn't destroy all information prior to it (so if it isn't a singularity).