Big Bang

[algonq5991]

Am I right to assume that if I had an imagery telescope and looked strait up at any point on the planet I could look back to the point of the big bang and if so if one was standing on the north pole and another on the south pole would we both see the point of origin of the universe

[Old_Geezer]

You are already at the point of the Big Bang. Everywhere is.

[ToraToraTora]

what OG said.

[factor-fiction]

What's an imagery telescope, alonq?

if you could see far enough into the universe and could see a clear image you could in theory see things as they were billions of years ago in theory but I'm not sure we can see things clearly enough that are billions of light years away

[mibn2cweus]

The point at which the universe began is now (and always was) distributed throughout the universe we now see (or the universe as it was at any point in time).

It's somewhat like looking for the first cell that became you. It grew and divided a million times to become you, so that in essence any part of your whole body is a part of that first cell.

[bookbinder]

How does anyone know that there was such a thing as the big bang? Nobody was there to record it.

[Peter Pedant]

// Nobody was there to record it.//

so science is only about things people have recorded ?
I dont think so

[Peter Pedant]

erm - no if the universe began three years ago
then you would only be able to see a sphere of three light years radius

( and there may e a bit of the universe beyond this, we dont know )

[Old_Geezer]

We "know" there was such a thing, as much as we "know" anything, because the affect can still be detected. Such as the patterns in the background cosmic radiation.

[Bazile]

Is the universe expanding faster than the speed of light ?

[jim360]

Not really sure I understand bookbinder's point. Suppose for the sake of argument you came across a whole bunch of rubble. You find bricks and mortar dust; material that could have been a carpet; various traces of wood; metal, some of it that was evidently once part of some piping. And so on, and so forth. At some point, staring at all this wreckage, you might eventually conclude that a house once stood here, but that it had blown up or been destroyed somehow. With a bit of work, you might even be able to make some decent estimates of how large the house was, and what sort of explosion might have been responsible for the damage seen. One way of doing this might be to construct your own miniature houses and blow them up, to see what gets leftover, and in doing so you can get a better idea of the shape of the house, its internal dimensions, how much wood and metal was inside, and whereabouts it was, etc etc. You can do all this and you don't need anyone to see that the house actually blew up.

In many ways, the same sort of thing is true of the Big Bang. The birth of the Universe is such a colossal event that it naturally can be expected to leave traces. Among other things, those traces include the CMB radiation. Although this was in fact formed a few hundred thousand years after the Big Bang, it nevertheless can be used to make some observations about the Big Bang (and other theories about the Early Universe) as each competing theory can be expected to leave distinct traces in that CMB.

Additionally, there is the point that the Universe is still expanding, which to some extent might be because the explosion hasn't finished yet (rather like, while standing by the rubble, a stray brick randomly falls out of the sky at your feet). And then to test some of the assumptions, various particle physics experiments essentially consist in smashing particles together at stupidly high energies and looking at the stuff that flies off. This is, hopefully, creating the conditions of the Early Universe a very short time after the Big Bang, and again allows you to test the competing models.

[Dizmo]

Bazile: You must have a better view than all of us in that starship of yours!

[Old_Geezer]

I'd suspect so Baz, but not being able to monitor any edge ... :-)

[anaxcrosswords]

I like the idea of the Big Bang and it seems logically sound, but I’ve always felt the logic has been pushed too far. It’s based on the idea that if the universe is bigger today than it was yesterday, then we keep scrolling back to the point at which it was basically a minuscule dot. Is there a reason to go that far?
What if all the matter we can see expanding outwards was originally compressed into a solid lump – that is, all the matter at the size it is now but with no space in between? Could that have led to this catastrophic event we call the Big Bang? And could the universe have already contained, at the time, a host of galaxies and other matter which were thrown outwards by the Big Bang and which, as a result, are too far away to be detected by any means we currently have?

[jim360]

I think there is a reason to go that far. The energies involved in throwing everything outwards for billions of years are colossal, too large really for just a normal compression to provide it. And the Big Bang also provides a beginning, which in itself is somewhat vital. An infinitely old Universe would be just filled uniformly with heat under the Second Law of Thermodynamics, and the only way around that is to ensure that the Universe isn't infinitely old (yet).

[Peter Pedant]

Hi Jim nice to see you contributing

[jim360]

It occurred to me that there's a more fundamental idea that explains why you have to go as far as the Big Bang. Really the Big Bang theory is about how space(time) started. The matter within the Universe then sort of goes along for the ride. Gather together all the matter in the Universe, visible or not, and compress it down as far as it will go, but otherwise have the Universe the same size as it was before, and what will happen is probably that you would get the Biggest Black hole that ever existed or can exist. Still a pretty awesome spectacle I'm sure, but while the result might include spewing stuff out in all directions it still wouldn't be able to create new space(time).

To blow spacetime up, you need a Big Bang (and, in particular, probably Inflation too), or at least some equivalent theory that not only explains the creation of matter, but also the creation of space and time itself. The way to do that involves starting everything off at stupendously small scales. Probably.

[Bazile]

//Bazile: You must have a better view than all of us in that starship of yours! //

No mate - it's very dark out here and another bulb has blown

[jim360]

Have you tried rerouting power through the main deflector?

[Bazile]

ok - so if the universe is expanding faster than the speed of light , how are we able to see for example the light from an exploding star , which occurred centuries ago .
How is the light from that star able to reach us here , where we are in the universe ?

[Bazile]

//Have you tried rerouting power through the main deflector? //

I thought about that but i dont want to overload the subspace accelerators