What happened before the Big Bang?

Claymore

Claymore

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Phil Plait, the Bad Astronomer, has posted an interesting bit on some new mathematics that may shed light on the origin of the universe:

What happened before the Big Bang?

What happened before the Big Bang? Does that question even make sense?

When astronomers think about the Big Bang, in general they don’t actually mean that one singular moment when the Universe burst into being. It’s really the name given to the model used to describe what happened an infinitesimally thin slice of time after that moment.

The problem is, right at that moment, at T=0, our laws of physics… well, they stall out. You wind up dividing by zero a lot, which causes a lot of headaches. You get things like zero volume and infinite density of matter and energy. It’s not that this moment didn’t exist physically, or that something impossible happened, it’s just that the math we currently use can’t describe it. And let me be clear: what happened after that one moment we can model fairly well. We may not have a complete picture, and the model may yet be supplanted (more on that in a moment), but we have a relatively (har har) good grasp on how the Universe behaved after T=+0.0000000000000…1 seconds. But at T=0, fuggeddaboutit. And T<0? The way the math works, that question doesn’t even make sense.

The basic trouble is that Einstein’s relativity gives us a good description of some things (large scale gravity, for example), and quantum mechanics tells us about other things (how particles behave), but no one has ever successfully combined the two, and they must be combined to understand that First Nanonanonanonanonanosecond. Einstein himself tried, and failed.

It’s possible, now, that this has changed.

Martin Bojowald, an assistant professor of physics at Penn State University, may have broken through this barrier for the first time. He is working on a theory called Loop Quantum Gravity, and it combines relativity and quantum mechanics. Using this new math, something amazing happens: at T=0, the volume of the Universe is not zero, and the density is not infinite.

In other words, the math still works, even at The Big Moment.

Loop Quantum Gravity has been around a while, but Bojowald appears to have simplified it, using different mathematical terminology. This allows solutions to be determined for what was, before, an intractable problem. And what his solution reveals is something that’s… well, it’s astonishing.

It’s been thought for sometime that there may have been some previous Universe that existed "before" ours. This is a difficult idea, because in the Big Bang model, space and time were created in that initial moment. But if Bojowald’s solutions are correct, it leads the way to understanding this previous Universe. It was out there, everywhere, and it contracted. Eventually it became an ultradense, ultrahot little ball of space and time. At some point, it got so small and so dense that bizarre quantum laws took effect — things like the Uncertainty Principle, which states that the more you know about one characteristic of an object (say, its position) the less you know about another (its velocity). There are several such laws, and they make it hard — impossible, really — to know everything about the universe at that moment.

What Bojowald’s work does, as I understand it (the paper as I write this is not out yet, so I am going by my limited knowledge of LQG and other theories like it) is simplify the math enough to be able to trace some properties of the Universe backwards, right down to T=0, which he calls the Big Bounce. The previous Universe collapsed down, and "bounced" outward again, forming our Universe. No doubt the physical aspects of this previous Universe were somewhat different; the quantum uncertainties at the moment of bounce would ensure that. It may have been much like ours, or it may have been quite alien. In his equations, it’s the volume of that previous Universe that cannot be determined. How big was it? It may literally be impossible to ever know.

In a sense, this uncertainty wipes the slate clean after a Universe crunches back down.

I want to stress that all of this is very interesting, and may possibly be borne out to be a better solution to the real physical situation of the Universe than anything we have now. Or, let’s face it: it might all eventually be tossed into the toilet. It’s a bit early to know. But it’s fascinating, and provides a glimpse into the future of cosmology, where we may not be limited by the one singular Universe in which we live. Another theory, called Brane Theory, is similar– it posits that there are other Universes as well, and they, well, they bounce back and forth, colliding every few hundred billion or trillion years. And that’s not even the weird part of brane theory… it might be able to explain dark matter and dark energy, and why our Universe appears to be accelerating. It’s well beyond what I can write for this blog entry (though it’ll be in my next book, heh heh). There is plenty of info on it on the web if you’re interested (here’s a good page to start you off).

Also, and what’s perhaps most exciting about these theories, is that they make predictions, predictions which can be verified or falsified based on observations. These are delicate experiments to be sure, but some will be possible to perform in just the next few years (for example, different cosmological origin theories predict different behaviors for the Universe at very early times, and these would imprint themselves on objects which can be observed).

These theories may seem like mumbo-jumbo or magic, but they have that very basic property of science: they’re testable.

And of course, I have to use this to stick it to the creationists once again. One thing they love to talk about is "fine tuning", how so many physical constants (like the charge on an electron, and the strength of gravity and the nuclear forces) appear to be incredibly well-adjusted to produce not just our Universe, but intelligent life in it: us.

Well, some of us.

The creationists claim that the only way this could possibly happen is if some sort of Intelligent Designer — and let’s not be coy, they mean God — set these values to be precisely what they are. Even just on its merits this isn’t right. I talked about this in the video clip I posted last week, so I won’t elaborate here. Go watch it.

But now we see another answer to the creationists: maybe this isn’t the only Universe. There might have been a string of them, reaching back in time, in meta-time beyond time. In those other Universes, maybe the electron had more charge, and stars couldn’t form. Or maybe it had less, and every star collapsed into a black hole. But if you get enough Universes, and the constants change in each one, then eventually one will get the mix right. Stars will last for billions of years, planets can form, life can evolve, and on one blue green ball of dust, chemicals can get complicated enough that they could look inside themselves, understand what they see, and marvel at the very fact of their own existence.

And maybe, just maybe, they can also figure out how it all came to be. This isn’t fantasy, folks, it’s science. It’s how things work.
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A book that really explains this well is Stephen Hawking's, "A brief history of time".

Its simple and well worth the read, even if you only have a BA degree :p

In fact there are no equations in the book at all, except for 1, since Hawking believed that each equation will half the book sales!
 
Regarding time: interesting to read is "A World Without Time - The forgotten legacy of Gödel and Einstein" by Palle Yourgrau...

In 1949, inspired by Einstein's ideas, Gödel proved that in any universe ruled by the Theory of Relativity, time simply cannot exist. Yet, in one of the greatest scandals of modern intellectual history, a conspiracy of silence has descended upon this idea: cosmologists and philosophers alike have proceeded with their work as if Gödel's proof never existed.
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In 1949, inspired by Einstein's ideas, Gödel proved that in any universe ruled by the Theory of Relativity, time simply cannot exist. Yet, in one of the greatest scandals of modern intellectual history, a conspiracy of silence has descended upon this idea: cosmologists and philosophers alike have proceeded with their work as if Gödel's proof never existed.
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We have devolved a universal complexity and called it time?
 
ettubrute said:
Regarding time: interesting to read is "A World Without Time - The forgotten legacy of Gödel and Einstein" by Palle Yourgrau...
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Is Gödels work actually relevant? What I mean is, that even though Einsteins work is flawed, it is still a work of genius and has the added benefit of being largely provable and probably useful.

Actually I'm not sure what point you are trying to make (didn't you post this somewhere else?). From what little I understand of Einsteins work I believe that the time referred to in relativity is not the same thing as what we generally perceive and refer to as time, i.e: not time in a chronological sense. Einsteins time is an abstract variable necessary for his calculations as far as I can tell.

So if the time that Gödel refers to is chronological time perhaps its a case of :"so what?".

Perhaps time really is an illusion. What good is that knowledge if you can't prove it or do something useful with it?

I'm always wary of claims of world-wide scientific conspiracies. I just can't see a bunch of genius' wasting their time with relativity if they secretly knew that it was all bollocks.
 
Nick333 said:
Actually I'm not sure what point you are trying to make (didn't you post this somewhere else?). From what little I understand of Einsteins work I believe that the time referred to in relativity is not the same thing as what we generally perceive and refer to as time, i.e: not time in a chronological sense. Einsteins time is an abstract variable necessary for his calculations as far as I can tell.
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It has been many years since I studied this, but my recollection is that one of the big things in Einstein's theory was that time isn't different to space. It is just our perception that time is unique and different to space.
 
I'm far from being an expert in this, but as I understand it, Einstein said that space and time were interwoven, and that dense objects like stars and black holes bend space/time around them. The analogy is something akin to putting a heavy weight on a suspended sheet and then rolling balls along the sheet - they will tend to curve around the weight. If you were to travel into a black hole, time would essentially stop.
 
Tassidar said:
If you were to travel into a black hole, time would essentially stop.
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That depends on your perspective. If you were in the black hole, time would continue on as normal, But If I was watching you "fall in", It would appear to me that you had frozen in time at the instant you entered. Hypothetical of course, since there is not a very high likelihood of you surviving the trip
 
Kalvaer said:
That depends on your perspective. If you were in the black hole, time would continue on as normal, But If I was watching you "fall in", It would appear to me that you had frozen in time at the instant you entered. Hypothetical of course, since there is not a very high likelihood of you surviving the trip
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As I understand it, for the person crossing beyond the event horizon:
Acceleration should (depending on the size of the black hole) become very great, leading to velocities approaching the speed of light. This would have three effects:
(1) Time would slow
(2) You would get very stretched along the axis of you acceleration
(3) Your mass would start approaching infinite.

From the perspective of someone looking at it:
You would appear increasingly red (because of the redshift of light climbing out), before fading away to nothing.
 
Tassidar said:
As I understand it, for the person crossing beyond the event horizon:
Acceleration should (depending on the size of the black hole) become very great, leading to velocities approaching the speed of light. This would have three effects:
(1) Time would slow
(2) You would get very stretched along the axis of you acceleration
(3) Your mass would start approaching infinite.

From the perspective of someone looking at it:
You would appear increasingly red (because of the redshift of light climbing out), before fading away to nothing.
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Further it can be added,

Speed is a scalar and velocity a vector, iow speed can not be negative.
Mass is a scalar and weight is vector, iow mass can not be negative.

Definitions:
SCALAR
Mathematics, Physics. a quantity possessing only magnitude.
VECTOR
a quantity possessing both magnitude and direction, represented by an arrow the direction of which indicates the direction of the quantity and the length of which is proportional to the magnitude.

In my personal opinion time is a magnitude without direction meaning T< 0 is not possible.
 
For some good reading relating to Godel's work, get a book called "Impossibility (the limits of science and the science of limits)" by John D Barrow. Very interesting (but intense).
 
Tassidar said:
As I understand it, for the person crossing beyond the event horizon:
Acceleration should (depending on the size of the black hole) become very great, leading to velocities approaching the speed of light. This would have three effects:
(1) Time would slow
(2) You would get very stretched along the axis of you acceleration
(3) Your mass would start approaching infinite.

From the perspective of someone looking at it:
You would appear increasingly red (because of the redshift of light climbing out), before fading away to nothing.
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I was thinking on the easiest way to explain this and asked somebody who knows 10 x more than me on this subject, to put it into laymans terms that I even I could understand (Especially since we argue about these things all the time) So this is my wifes edited reply via email to me (Oh and before anyone asks.. this is her field of work and study)

"Okey dokey...

First on the space/time issue: In Einstein's Special Relativity (1905) he showed that space and time are not absolute - that is, what I call "space" or "time" can be different to what you call "space" and "time", and will be if we are moving at different velocities.

Further, he showed that time and space are not separate. Time is the 4th dimension that we move in, just like the three space dimensions are x, y, and z (or left/right, forward/backward, up/down). The thing that makes time different from space is that we can only move in one direction in time... We can only move forward in time. Whereas in space we are free to move left OR right, forwards OR backwards, up OR down. This is why we perceive the time dimension to be different to the space ones.

On the black holes: In Einstein'd General Relativity paper (1915) he went on to show that gravity is geometry. That is, just as you can explain the "centrifugal force" by noting that you are in a rotating reference frame (as opposed to one at rest), gravity can be explained by noting that you are no longer in "flat" spacetime, but rather in spacetime that is curved.

The thing about black holes is that they curve spacetime so much, that you have to exceed the speed of light to escape them." Like you said, "imagine rolling balls around a curved sheet. The deeper the curve, the faster you have to roll the ball to get it out of the dent. For a black hole, the dent is so steep that you would have to roll the ball faster than the speed of light to get out of it, which of course is impossible.

However, going faster than the speed of light is only necessary for leaving the black hole. You don't have to go anywhere near the speed of light to fall in it, so your mass would not get infinite." (Your point 3)

"Onto falling into black holes... Let's say that I'm an astronaut falling in towards a black hole, and you are on a spaceship watching me. I have a watch on my arm, and you have a clock on your spaceship. We start off with both our clocks synchronized.

As I get closer to the event horizon, the black hole's gravity is starting to distort space. Light bouncing off me has to fight against the gravity to get back to you on the spaceship, so I appear redder to you", again as you said. "However, the gravity is only affecting MY time on MY watch - you are safely away from the black hole, so to you it looks like my clock is running slow. However, to me, it looks like my clock is running perfectly normally, and yours is the one that is slow. Time does NOT actually slow down, it is only an affect of how we measure it (in curved spacetime) that makes it appear so.

I would get very stretched out, this is called spaghettification. :) What happens is that (imagine I'm going into the black hole feet first) the gravity pulling on my feet is much much stronger than the gravity pulling on my head. This is because of the "steepness" of the black hole's gravitational "well". Anyway, I'd be stretched out longer and thinner as I approached the BH, until I got torn apart. Not a pleasant experience :) Ironically, it would be "safer" to go into a really massive black hole, since the gravitational slope is shallower. If I chose a black hole of about 10 million times our sun's mass, I would feel only slight spaghettification forces - not enough to kill me :)

As I approach the event horizon, I become almost invisible as the light bouncing off me loses most of it's energy in it's escape. For you watching on the spaceship, my watch runs slower and slower as I approach the black hole, until it appears to stop completely at the event horizon. You would not see me cross the event horizon, I would appear to hover outside it for infinite time."
 
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The basic trouble is that Einstein’s relativity gives us a good description of some things (large scale gravity, for example), and quantum mechanics tells us about other things (how particles behave), but no one has ever successfully combined the two, and they must be combined to understand that First Nanonanonanonanonanosecond. Einstein himself tried, and failed.
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This is the crux of Stephen Hawking's work. He has achieved the marriage between relativity and quantum theory quite adequately. Most cosmologists (astronomers are not exactly the best equipped Scientists for this type of research) believe if Einstein had more time he would have achieved this as well.
 
Hmm not at all.. Nobody has got even close to marrying the two. If anything String theorists might be on the right track to getting it done. Even so, String theory is far from complete and as yet has no way of being proven experimentally. A quote I love from the DVD collection (The Elegant Universe) and I believe it was Ed Witten who said something on the lines of "Anyone who says they understand string theory, dont understand anything about it at all"

The problem with the book that most mention for this topic ("the brief history of time"), is that while it touches on many subjects which are still valid, it was done before cosmologists discovered that the expansion of the universe is accelerating, This of course means that some of what is said in this book about the evolution of the universe, is out of date.
 
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