Radiation of the Big Bang

Hello everyone, I'm new to this forum, and therefore feel absolutely free to correct me if I make any mistakes in posting or so forth.Anyway, I wanted to ask something about the Big Bang theory that doesn't make any sense to me. As I understand, before the Big Bang actually occurred, the universe was compacted in an extremely dense point, which contained all our matter, space-time, etc.
My question is sort of paradoxial I guess, but how could this point radiate energy?The thing is, all matter above 0 Kelvin radiates and absorbs energy of one kind or another right? So such a point must have been radiating infra-red, visible light, all kinds of radiation. But if there was no space-time outside of this point, how would that be possible?I really am just curious on this, and any more information on the specifics of Big Bang theory in general would be appreciated.

Thread moved here from the Proposed New Topics forum.

I'm no expert but I was under the impression that untill a certain point after T=0 you did not have radiation.As I undersatnd it after planck epoch you get quarks and gluons buzzing around in some kind of plasma.You don't get radiation at this point in time because the fields are not distinct yet.Hope that helps.

We don't know what happened "before the big bang occured". The superdense point is the extreme extrapolation of what we know but it goes past anything we understand. We know it was very, very, very, very dense 10 to the -41 seconds later but the actual point is probably a mathematical error not a physical reality.

There is no space-time outside of the universe. So if there was radiation occurring, it was occurring inside the universe like it is today.

Thanks guys, that clears things up a bit.

Hi Othrus, One thing to keep in mind is that the BB didn't actually occur. And occurrence references a 'time' and a 'place' where an event happened, this is logically impossible "before" the BB since there was no space or time for anything to occur. It is just the name given to the cosmological expansion.Before the expansion, according to GR, the universe is infinitely dense and curved - but this is only do to the limits of GR not being able to give proper relativistic calculations for sub-atomic scales. Curiously, there was no spacetime - that makes sense to us - at this point either. How can there exist an "outside" to something that doesn't exist? Basically, the universe is expanding at an accelerated rate, been doing so for about 14 By. - thats the short and skinny of it.Edited by onifre, : No reason given.

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"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks"I never knew there was another option other than to question everything"--Noam Chomsky

Before I start please keep in mind that I do not have a degree in physics (but I do have one in Zoology), and everything I understand about the Big Bang and the rest of theoretical physics comes from popular press books. However, I do feel that I have a pretty good handle on what is going on in the world of theoretical physics. With that said . . . From my understanding, the singularity did not contain spacetime nor matter. Just energy. That's it.Secondly, it couldn't radiate into spacetime because there was no spacetime. Was this energy interacting? I think the evidence says "YES". This is because the "temperature" across the universe is very even. This means that energy in the era before the Big Bang (notice that I didn't say "time previous to the Big Bang) probably did interact somehow. As an analogy, the temperature on one side of your beer is the same as the other because the two sides of your beer are able to interact. I could be completely wrong, but that is my understanding of what I have watched on very poor documentaries on the History channel and various popular press books.However, the initial expansion of our universe is another thing altogether. As an analogy, imagine a very violent and dense mosh pit at a punk concert. Imagine that this mosh pit was confined by impenetrable walls. Now imagine what happens if these walls just disappear. Everyone in the mosh pit starts moving out in all directions, right? That's what happened to the energy in our universe. It suddenly had a lot more room to move around in. As a result, it was able to cool down enough to form matter, and much later it was cool enough to form complete atoms (which marked the production of the cosmic microwave background).The Big Bang theory is derived and supported by radiation in our own universe. You were pretty close with your gut reaction to the theory.Edited by Taq, : No reason given.

I too am not a physicist but rather am a layman. However, physics and science in general are one of the "loves" of my life, metaphorically speaking. Here is how I understand it.You are right in that the BB singularity does not contain spacetime. Rather, the BB singularity IS spacetime, that is all of spacetime curved to infinity. Basically the Big Bang singularity is a very high amount of matter/energy (all the energy/matter in our universe) condenced into 0 volume, thus resulting in an infinite density.If we transformed our 3 dimensional universe into 2 dimensions, a singularity would look something like this: Except that there is not a single point at the bottom as this image displays but rather the point would reach to infinity off the bottom of the page. This is not a time graph but rather just a spacial representation of the singularity of the BB (which also applies to black holes). The only difference between the BB and black hole singularities is the amount of energy/matter involved.Here is a more accurate representation of the BB singularity on a time scale, with significant events annotated: You are also right to say that only energy is involved in the BB singularity as matter had not yet condensed out of the energy soup of the pre-inflation BB. Just remember that matter and energy are intricately linked and are in fact two forms of the same "substance". Also energy, matter, space and time are all intricately related and effect each other. That is the greater the amount of energy/matter the more space/time is curved as described by Albert Einstein's GTR.Hope this helps.Edited by DevilsAdvocate, : No reason given.

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

It wasn't and it didn't. Like Taq stated, the BB singularity was only energy, no matter had yet coalesced from this energy, condensed to 0 volume and an infinite density (and extremely high temperatures). However, there would be nowhere for this energy to radiate to, remember singularity is 0 volume and there is no "spacetime" outside of the spacetime of singularity (extra dimensions is a different story but we are talking about 3d spacetime not the curled up multiple dimensions of M/string theory which do not contradict the BB theory but rather expounds on it).Spacetime itself inflated very rapidly from singularity due to quantum flunctuations at which time the energy started to dissipate (because the volume/area of spacetime itself was expanding). This dissipation of energy drove down the temperature down (just like a propane bottle's valve cools when the valve is opened and the bottle decreases in pressure when its gaseous contents escape), thus allowing matter to coalesce out of this energy soup. Subatomic particles formed, than ions, than full fledged atoms with there electron components and then more massive structures such as stars, planets and galaxies.It was not until 300-400k years after the BB, that the radiation in the form of EM radiation (radio waves, microwaves, infared, light, etc) was able to travel without being impeeded/absorbed by the previous hot, opaque, glowing ion mass of which the universe before that time was composed of.

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For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan

One other thing worthy of note is that all 4 known forces: strong, weak,electro-magnetic and gravity were all combined in the pre-BB singularity. In the very first few nano-seconds after the Big Bang, gravity separated from the other 3 forces since it was the weakest of all forces. The other forces were responsible for the condensing of the quark soup into all the particles that make up our universe today over a period of about 300-400k years. Only after that period of time did the first stars begin to form and gather into galaxies.To answer the original question about radiation not extending beyond the singularity - with all the forces combined in the singularity, it would not be possible to emit radiation. This is because the forces responsible for radiation (ie: weak & eletro-magnetic) would be wrapped up inside the singularity. The strong force responsible for combining quarks into all known particles which make up matter was also held in this singularity. The mass of the entire known universe was compressed into the singularity held together by gravitational force like a tightly wound spring waiting for its enormous energy to be released.Scientists at CERN are trying to recreate on a very tiny and minute scale the energy necessary to bring these 4 forces together as it was before the BB. To date they have only been able to combine the 3 greater forces (strong,weak & electro-magnetic). If successful, we may someday discover the relationship between gravity and the other 3 forces and put this knowledge to good use for all mankind.

Or, more likely find out some new cool law of quantum physics that does not add much productive to the world.

**Correction: I meant to say that atoms formed 300,000 years after the BB and stars began forming about 300 million years after the BB.