Before the Big Bang?

Shnoz (Sophie) · #1 04-08-2009, 08:50 PM

Hi everyone!
My physics teacher and I were having an educated debate this afternoon about the laws of physics before the Big Bang.
My teacher believes there can't have been nothing before the Big Bang, as you cannot get something from nothing.
I then rebutted this with if there was truly nothing before the Big Bang then there would be no laws of physics and therefore nothing to say that something cannot come from nothing.
I don't think I really convinced my teacher and he is free to hold his own views, as I know nothing more than he does about the origins of the universe.

I was however wondering what other theories and hypothesises there are as to what was 'before' the Big Bang.

xelasnave · #2 04-08-2009, 09:53 PM

Quantum fluctuations

alex

ngcles · #3 04-08-2009, 11:41 PM

Hi Shnoz,

Hmmm ...

I am usually loathe to comment on cosmological issues or matters of deep physics because I am woefully under-quallified and frankly it gives me bad headaches but ...

According to the current standard model space-time is as much a creation of the event that brought all the matter/anti-matter and the laws of physics into existence in what we refer to as the "big-bang". ie space-time came into existence with the big bang. There was no space-time before the big-bang.

Therefore, as I understand it, there was no "time" and no "before" the big-bang -- time did not (and could not) exist until the big-bang brought it into existence. There is no before, only after.

How can something come out of nothing? Hasn't your Physics teacher heard of quantum theory? Vacuum polariszation? Perhaps he is uncertain about it?

Alex hit the nail on the head (see above) with his comment.

Best,

Les D

renormalised (Carl) · #4 05-08-2009, 12:59 AM

Very good arguments, Sophie. If your teacher is any sort of teacher...and a scientist, he'll think long and hard about your conversation. It should make him think and read up on the latest papers.

I won't go into the maths for the current theories...I have a hard enough time trying to follow it myself, but I'll try and explain to you one of the ideas they have now. It's called M-Theory....don't ask me what the M stands for because no one else does. Call it "magic" if you will. Anyhow, it was proposed by a physicist named Edward Witten from The Institute for Advanced Studies at Princeton University, back in the early 80's. What he proposed is that our universe, which they believe is made up of extremely tiny vibrating packets of energy, called strings (have you heard of String Theory??), is nothing more than a 4D (3 physical dimensions and 1 time dimension) surface of a much larger, multidimensional object, called a "brane" or membrane. Now, what this membrane is, so the theory goes...is a string that has stretched itself out into a flat surface, a membrane (or brane) which lies in a higher dimensional hyperspace. Now in that higher space, there are also other membranes, other universes if you will. Every now and then (probably over many trillions of years) these branes which are floating about in this higher space collide, and it is this collision which is the "Big Bang". After the collision, the branes rebound and move away from one another. Now, whilst time and space may appear to have come into existence on our own particular brane at the Big Bang, in actual fact (according to theory) what happens is that time and space merely reach a bottleneck. What in fact occurs is that time and space from the previous cycle of expansion comes to that bottleneck and then a new set of conditions occurs for the next cycle of expansion with little or no information from the previous cycle coming through to the new one (as far as we know. There maybe some informtion which slips through). There is no "Big Crunch" so to speak. At each expansion phase, the universe which forms in the brane keeps on expanding until it becomes completely smooth and homogenous in its internal structure i.e. nothing but spacetime left, not even electrons, protons or quarks!!!. Spacetime itself keeps expanding until the brane in which it sits collides again with another brane, everything becomes reset instantly and a new set of conditions arises in the brane, generating another cycle of expansion for a new universe in the brane. Hard to visualise?? Think of it like this...take two pieces of paper and bang them together, then scrunch one of them up. Then over an hour, say, gradually unfold and smooth that bit of paper out. Once you get it as smooth and flat as you can, bang the two bits of paper together again, then scrunch that piece back up. Do the same process again and again and again...indefinetly. That's a rough analogue of what happens, according to theory.

It's late and I hope I've made some sense to you (hard to think when you're tired!!!). But if you need anymore explanatory notes, just ask. Or one of the other guys might take it up...(keep it easy, hey!!).

xelasnave · #5 05-08-2009, 09:04 AM

I heard the "M" is an upside down "W" as a back hand reference with humility to the man behind the theory.

Is big bang still a theory or now a fact?
Has the posibility of alternate theories been removed?
Could the Universe be infinite...no top, no sides, no bottom no start and no end...
I feel uncomfortable with the big bang in a few respects irrespective of the infalibility of the math...
Firstly the observation that the Universe is expanding may be flawed but if expanding does such an observation entitle an extrapolation back to a point with in a split split second of the appearance of everything...
It was a seed so to speak but was everything ...what was on the outside of this seed at that time?
And in a short time thereafter the Universe moved into its "inflation" stage (a "theory" proposed by one of Withens associates Guth) wherein we are asked to entertain the prospect that from its most small beginings and in some 30 seconds the Universe expanded to near its current size..which I believe is placed at approx 160 billion light years ...well I read it on the net so who knows but it seemed plausible ...

I understand the inflation theory saved the big bang theory and notwithsatanding any math in support to think we can go from the size of a base ball to all there is now (within 14 odd billion light years) seems beyond acceptance and for me throws doubt on the theory... inflation is hardley a theory in so far it as far as I know not met standard scientific requirement for a "theory" ...

Anyways Sophie as much as folk speculate upon the Universe I doubt if we are anywheres near the truth of what it is why its there etc...

I look at the maps and cant help but think the layout is very like a blood circulatory system... maybe we are part ofd some much much larger creature even...

Junk food for though good luck with your quest for knowledge.

alex

sally1jack (Phil) · #6 05-08-2009, 09:47 AM

Quote:

Originally Posted by xelasnave

Anyways Sophie as much as folk speculate upon the Universe I doubt if we are anywheres near the truth of what it is why its there etc...

alex

& does it matter anyway

gman (Grant) · #7 05-08-2009, 10:00 AM

A question in relation to the Big Bang theory.

Has anyone calculated the force required to project all matter etc from a central point to over a 160 billion light year area in 30 odd seconds and what could have or needed to be to produce that force?

I can't even begin to imagine the force required to make this happen

renormalised (Carl) · #8 05-08-2009, 10:35 AM

Quote:

Originally Posted by xelasnave

I heard the "M" is an upside down "W" as a back hand reference with humility to the man behind the theory.

Is big bang still a theory or now a fact?
Has the posibility of alternate theories been removed?
Could the Universe be infinite...no top, no sides, no bottom no start and no end...
I feel uncomfortable with the big bang in a few respects irrespective of the infalibility of the math...
Firstly the observation that the Universe is expanding may be flawed but if expanding does such an observation entitle an extrapolation back to a point with in a split split second of the appearance of everything...
It was a seed so to speak but was everything ...what was on the outside of this seed at that time?
And in a short time thereafter the Universe moved into its "inflation" stage (a "theory" proposed by one of Withens associates Guth) wherein we are asked to entertain the prospect that from its most small beginings and in some 30 seconds the Universe expanded to near its current size..which I believe is placed at approx 160 billion light years ...well I read it on the net so who knows but it seemed plausible ...

I understand the inflation theory saved the big bang theory and notwithsatanding any math in support to think we can go from the size of a base ball to all there is now (within 14 odd billion light years) seems beyond acceptance and for me throws doubt on the theory... inflation is hardley a theory in so far it as far as I know not met standard scientific requirement for a "theory" ...

Anyways Sophie as much as folk speculate upon the Universe I doubt if we are anywheres near the truth of what it is why its there etc...

I look at the maps and cant help but think the layout is very like a blood circulatory system... maybe we are part ofd some much much larger creature even...

Junk food for though good luck with your quest for knowledge.

alex

Big Bang cosmology is still the best and universally accepted theory as to how the universe began. It's not incontrovertible though and there is still quite a bit left to work on, but it's the best we have at present. Basically, these other theories, like M Theory, extend the basic idea of Big Bang cosmology but come at it from different angles....correct faults which are in the standard interpretation and suggest new ways of looking at what happened.

The universe underwent inflation in an extremely short period of time (inflation started at around 10^-37sec and ended at 10^-35sec) and expanded something like 10^50 times its size. The local universe, that which we see, went from that infinitesimal size to about the size of a grapefruit, but spacetime itself...the universe as a whole....expanded enormously. 160 billion ly would be a small fraction of that size. It helps explain why the geometry of the universe appears to be flat, even if the overall geometry of the universe is saddle shaped (open topology). Each separate region of the universe....each local universe as defined by the speed of light horizon, then continued to expand at it's own pace and would've only become aware of the existence of others when their horizon distances crossed over one another and they merged. So, as each region expanded and merged, the local universe, as defined by the horizon distance, grew larger till we have what we see today. But now, we have to factor in cosmic acceleration because since about 2 billion years after the initial bang, the universe has been speeding up its rate of expansion. This is where "dark energy" comes into the equation. They don't know what it is. It's been defined as the cosmological constant (Einstein's "greatest mistake", or so he said himself) and it's presence, over time, causes the expansion rate to increase as it becomes dominant over gravity.

Inflation is a solid scientific theory, Alex. It is testable and can be falsified so it fits the definition of a scientific theory. It's testable through observation and can be falsified if a better idea comes along to displace it, but so far none has...but that doesn't make it wrong because it hasn't undergone the falsifiability premise.

If you really find it a little hard to grasp, here's a site which may help....

Inflation

If you have any questions afterwards, just post them here and someone will answer them....it may not be me, but someone who has some knowledge of the matter will be online to answer them

renormalised (Carl) · #9 05-08-2009, 10:44 AM

Quote:

Originally Posted by gman

A question in relation to the Big Bang theory.

Has anyone calculated the force required to project all matter etc from a central point to over a 160 billion light year area in 30 odd seconds and what could have or needed to be to produce that force?

I can't even begin to imagine the force required to make this happen

You're labouring under the impression that there was a central point of expansion. With respect to the universe itself as we see it, there was no central point. The expansion happened everywhere, simultaneously. If you were to define a central point of expansion, it would have to lie outside of spacetime as we see it.

There was no force, as we would define it, that can be calculated. It was spacetime itself which expanded....now this would take enormous energy, however, a force needs a carrier particle to propagate that force and the domain in which that force is exerted is the force field. Since those particles belong to spacetime itself and arise out of it the best you can say is that it was a "universal force" in size that drove the expansion. The force was spacetime itself and spacetime expanded of its own volition, once set in motion.

Karls48 (Karl) · #10 05-08-2009, 10:55 AM

I consider Cosmology together with Economic, Meteorology and Psychology as very inexact science at best. At worst it can be compared to Astrology. When and if we explore our Galaxy we may have begin to have some idea about what the Universe is and if there is something beyond of it.
At any point of time in history people thought that they know it all, they know most of the answers. Today scientists are not different from the ones in the past.

renormalised (Carl) · #11 05-08-2009, 11:04 AM

Quote:

Originally Posted by Karls48

...At any point of time in history people thought that they know it all, they know most of the answers. Today scientists are not different from the ones in the past.

That is so true. Even though we may think we know all that there is to know, we don't. Much of our knowledge now will more than likely be rather quaint in 100 to 200 years time. That's why you should never rule anything out.

sjastro · #12 05-08-2009, 11:09 AM

Quote:

Originally Posted by Shnoz

Hi everyone!
My physics teacher and I were having an educated debate this afternoon about the laws of physics before the Big Bang.
My teacher believes there can't have been nothing before the Big Bang, as you cannot get something from nothing.
I then rebutted this with if there was truly nothing before the Big Bang then there would be no laws of physics and therefore nothing to say that something cannot come from nothing.
I don't think I really convinced my teacher and he is free to hold his own views, as I know nothing more than he does about the origins of the universe.

I was however wondering what other theories and hypothesises there are as to what was 'before' the Big Bang.

Hello Sophie,

Our Universe has evolved by the laws of physics changing. In the language of the particle physicist this is known as spontaneous symmetry breaking.

For example the laws of physics of the Universe 10^-43 sec after the BB were quite different to what they are today. The symmetry of the Universe was described by a single force. Today there are 4 forces.

There are mathematical gauge theories that attempt to describe a symmetry before the BB.

In a sense the laws of physics popped into existence with the BB.

Regards

Steven

sjastro · #13 05-08-2009, 11:15 AM

Quote:

And in a short time thereafter the Universe moved into its "inflation" stage (a "theory" proposed by one of Withens associates Guth) wherein we are asked to entertain the prospect that from its most small beginings and in some 30 seconds the Universe expanded to near its current size..which I believe is placed at approx 160 billion light years ...well I read it on the net so who knows but it seemed plausible ...

Alex you must be living in a different Universe to mine.
In my Universe inflation only lasted for a fraction of a second where the Universe expanded from the size of an atom to that of a grapefruit.

Steven

renormalised (Carl) · #14 05-08-2009, 11:47 AM

Quote:

Originally Posted by sjastro

Alex you must be living in a different Universe to mine.
In my Universe inflation only lasted for a fraction of a second where the Universe expanded from the size of an atom to that of a grapefruit.

Steven

I was going to say the same thing, but I tried to explain it instead, in easy terms. In any case, that grapefruit sized universe was only just the local "bubble".

Mind you, how big were the grapefruit in those days....probably not even big enough to fill a hollow proton!!!

Not much to eat

xelasnave · #15 05-08-2009, 05:40 PM

Quote:

Originally Posted by sjastro

Alex you must be living in a different Universe to mine.
In my Universe inflation only lasted for a fraction of a second where the Universe expanded from the size of an atom to that of a grapefruit.

Steven

Must be to do with relativity

Your view is of no surprise as I take all that I read as having another view point ... some say we started with a seed and others say the big bang was all over..and perhaps both may be correct for even if the size of a grapefuit the Universe is indeed the universe and, as it is all that is, a comparrision to anything we can relate to will be difficult no doubt.

Still my defence is simply it was out there someplace and I will not take responsibility for inventing my current belief as to what is laid down by "inflation" or anything that would lend support for the notion of inflation..

I simply dont buy it and I really feel that in doing so we may not pursue a more suitable and reasonable view...inflation has stopped questions asked that inflation sought to satisfy.

Still an expansion from an atom to the size of a grapfruit is a rather huge jump in size..relatively..and perhaps it is even easier to cast doubt upon the theory and its reasonableness as we can comprehend something very small and how magical it would be therefore even if say an ant were to expand in size such that it now matches a grap fruit..in a mere fraction of a second... I mean how could such a thing happen.

We talk of "space time" as if when such words are invoked we must accept mysterious notions as being reasonable but "space time" is not a mystery it is a geometric way of setting out what we observe in terms humans can work with....and I still suspect that the theory was grabed too eagerly in order to save the then dieing notion of the big bang...

But we all live in different Universes and we are each at the very center of the one to which we belong

Hope all is well in your Universe Steven

.

alex

xelasnave · #16 05-08-2009, 05:56 PM

Carl said.....

Inflation is a solid scientific theory, Alex. It is testable and can be falsified so it fits the definition of a scientific theory. It's testable through observation and can be falsified if a better idea comes along to displace it, but so far none has...but that doesn't make it wrong because it hasn't undergone the falsifiability premise.

Carl maybe I was hasty but I am not aware of the testability of the theory, no is there anything in the way of experimental observation as far as I know...not that I could know everything out there but from all I have read to me it seemed to fail the test of what constituted a scientific theory... still if there is something more I would love to read about it...for although I must sound sceptical etc I simply dislike the way some notions claim the status of theory.

AND how could it be falisified? really the custom surrounding theory and falisibiliy means in effect if I claim a theory it stands until someone can prove it wrong... in these areas how can you really prove anything ..we are dealing with stuff that happened some 13.5 approx billion years ago and I suspect all eye witnesses have long passed on...

You also said....

"160 billion ly would be a small fraction of that size"...
Is there any most widely accepted opinion on the size of the Universe... 160 is the largest guess I have read ...

best wishes
alex

renormalised (Carl) · #17 05-08-2009, 05:57 PM

If you find inflation and such hard to swallow, Alex, and you have some ideas of your own, then by all means make them known. What you have to realise is that whatever you may come up with has to fit the observations made by astronomers and that they are testable (to the extent that anything like this can be tested). You need to be able to show that your ideas are more accurate in explaining what's been found and that there are little or no inconsistencies or anomalies in your workings. In short, can they be described mathematically.

xelasnave · #18 05-08-2009, 06:03 PM

I had no idea that the idea was also considered by Alexei Starobinski at the same time as Alan Guth I mean what are the chances .... but that sort of thing happens so often it makes me wonder if ideas float in the aether available to those considering a particular matter... not really but the coincidence of like thought is rather common.

alex

Shnoz (Sophie) · #19 05-08-2009, 06:06 PM

Speaking of large expansions of space-time, is space-time able to move faster than the speed of light? Or is there a technicality that allows the universe to expand as it does without breaking the 'universal speed-limit'?

renormalised (Carl) · #20 05-08-2009, 06:08 PM

When you go to test a theory, you set up a null hypothesis saying, in the case, " The observations that have been made currently by our telescopes proves that inflation did not occur". Null hypotheses are generally the negative arguments to the theory you are testing. Now you have a basis on which to test the falseness of this assumption. You go through all the related observations and see whether what they've found either supports or rejects that negative notion. You do the maths and physics for the observations made, see if they support or reject the what you're trying to find. After all that work, you then discuss your findings with colleagues, modify whatever needs to be modified, retest everything and discuss again until you have come to a satisfactory conclusion that your theory holds, or the null hypothesis holds and then you propose your theory. If you reject it, then you modify it again and again, or reject it outright and look for something new.

That's what they call the Scientific Method.