Thread: Silly question about the Big Bang

Hello;

I'm curious: how do we know (if we do) that all matter and energy in the universe comes from the Big Bang?

Can't there have been, say, a star, a comet, even just a pebble somewhere in space beside the "Big Grenade" (whatever it is called, the Primeval Atom, Original Singularity or anything) prior to its detonation? One that was or was not transformed/burnt/evaporated/plasma-fied in the BB?

The big bang is thought to be the origin of space and time as well, not just matter. So there would not have a place for the pebble to exist in, according to the theory at least.

The silly answer is that we don't.

Science is the merciless guardian of what can be known through tests that match observations. So if I make a prediction that can never be falsified, then that would not be science. Until we find a way to interact with something "before the Big Bang" or "outside the known universe", then there is not a practical way for any such thing to be scientifically known. Colliding Branes may have caused the Big Bang. Gravity may exist on another dimension and "leak" into our universe. We just won't know until we find a way to prove these things.

Originally Posted by KALSTER

The big bang is thought to be the origin of space and time as well, not just matter.

Is it because some observed facts indicate there was no space or time prior to the Big Bang?

Or is it that - according to theories I have heard of but which are way above my head - space and time only exist where there is matter, and the assumption is that, outside the Original Singularity, there wasn't?

In the second case, if there was indeed a pebble somewhere outside, there was also space (and time), and the BB just filled it with a lot more matter and energy?

As I understand it and very basically, it works like this:

Everything seems to be moving away from us and at a faster rate the further it is away from us. The only possible way this can be (as far as we know for now) is if space is expanding. If space is expanding, it would mean, if you turn back the clock, that at one point all matter and space was collected in one place. There is also no reason to assume that the Solar system was somehow at the centre of this whole event and the concept of space curvature takes care of that quite nicely. It means that you could be at any point in the universe and you would still see everything else moving away from you. It also means that no "outside" of the universe can exist and no "edge" could ever be reached. That pebble of yours apart from our universe would be like trying to think about the print on the 7th side of a standard die. There simply is no 7th side to print something on in the first place.

Having said all of the above though, I can't think of a reason why the expanding universe cannot be, say, trillions of light years across and that the big bang happened in an existing universe, perhaps even an infinite one. In that case you would have to go very far before you started to see the receding speed of distant galaxies equalize.

Anyway this is how I understand it, but I am very open to correction.

The big bang theory is based on interpreting the increase in wavelength of the light from galaxies as a Doppler Effect.

The light increases in wavelength through encountering decreasing density of light. The big bang theory is wrong.

See the essay posted at http://members.westnet.com.au/paradigm/forever.pdf

Stephen

Originally Posted by Leszek Luchowski

Hello;

I'm curious: how do we know (if we do) that all matter and energy in the universe comes from the Big Bang?

Well actually we don't know, the Big Bang is just a theory after all.

I mean we really don't know though, science just tries to disprove religion as well, and again, everything which can't be proved without question, even with so-called "physical impossibility", is still just a thought or theory, and the ignorance of it still stands.

Originally Posted by KALSTER

As I understand it and very basically, it works like this:

Everything seems to be moving away from us and at a faster rate the further it is away from us. The only possible way this can be (as far as we know for now) is if space is expanding. If space is expanding, it would mean, if you turn back the clock, that at one point all matter and space was collected in one place.
(...)
Having said all of the above though, I can't think of a reason why the expanding universe cannot be, say, trillions of light years across and that the big bang happened in an existing universe, perhaps even an infinite one. In that case you would have to go very far before you started to see the receding speed of distant galaxies equalize.

Thank you Kalster; allow me to probe you further:

Why do you equate space with matter? I mean, couldn't just matter be rushing away from some central point, as in any ordinary explosion (be it a New Year firecracker or a supernova) in a nice, infinite, continuous Euclidean space? In which case if you turn back the clock you get a very small (maybe even infinitely small) but unimaginably massive lump of matter in the same nice infinite space, which may or may not also contain other lumps of matter, of assorted sizes and, erm, massivenesses?

Those other lumps of matter might be to small, too dark, or too far away (or all three) for our telescopes and other observation methods.

As I wrote this, it occurred to me that an object as tiny and as massive as the Original Singularity would normally constitute a black hole. Why didn't that one? Or if it did, could it be that it still does and our "space" is its inside? With possibly some matter existing outside that we don't know of? That matter would have to be far away or else it would be raining right into our universe...

Sorry, I know the answers to my questions can be found in any course of cosmology, but I am just a curious layman...