How is there enough evidence to prove the big bang?

ScumLord

I fear I may not understand the answer to this question but after watching documentary's that say scientists can track the movement of galaxies back to a single point that would have been the big bang but I'm wondering what with the size of the universe how we've really seen enough of it to conclude everything came from a single point?

Surely we can't actually see the other side of the universe to see the galaxies racing away on the other side of the explosion. So all we would actually know from the galaxies around us is that galaxies are moving in one particular direction, how do they know we're not moving in one direction down a tube or something?

Calibos

They are not moving in the one direction. Beyond the local groups of galaxies one sees that every galaxy is moving away from us as if we where the centre of the universe. The thing is that no matter where you are in the universe every other galaxy would look like it was moving directly away from you. Everywhere can't be the centre of the universe at the same time. The only explanation is that space itself is expanding from a singularity...the big bang.

It was explained to me thus. Imagine the 2 dimensional surface of a balloon is the 3D universe. Draw a load of dots on the surface of the balloon to represent galaxies. Start to inflate the baloon. Every dot/ galaxy receeds from every other dot/galaxy as the balloon/universe expands. Galaxies do have proper movement within the universe and we can see that on a local galactic scale. ie we know Andromeda is heading towards us. However on the large scale, the fact that every galaxy is moving away from every other galaxy isn't proper movement its that the space in between every galaxy is stretching as it were. The dots aren't moving, The balloon surface is expanding between the dots.

The only explanation for this is a singularity and a big bang.

mike65

The universe is like a loaf of suspended bread in the oven.

ScumLord

Calibos wrote: »

It was explained to me thus. Imagine the 2 dimensional surface of a balloon is the 3D universe. Draw a load of dots on the surface of the balloon to represent galaxies. Start to inflate the baloon. Every dot/ galaxy receeds from every other dot/galaxy as the balloon/universe expands. Galaxies do have proper movement within the universe and we can see that on a local galactic scale. ie we know Andromeda is heading towards us. However on the large scale, the fact that every galaxy is moving away from every other galaxy isn't proper movement its that the space in between every galaxy is stretching as it were. The dots aren't moving, The balloon surface is expanding between the dots.

The only explanation for this is a singularity and a big bang.

That makes sense in 2 dimensions but in 3 it doesn't to me at the moment.

Every galaxy should be moving away from the center of the explosion. On the surface of the balloon they should be speeding away from each other but moving in the same direction as each other away from the center of the explosion, unless that is whats happening. Even if it is happening surely we can only see a small arc of that explosion, meaning we couldn't really say we're not seeing a shotgun spray effect instead of a full explosion.

FISMA

Your title " How is there enough evidence to prove the big bang?" is mixing words.

Evidence does not equal proof.

This is why we have theories.

Proof to scientists requires testing, reproducing, and such.

For example, most people accept that [most] atoms are made out of: protons, neutrons, and electrons.

Rutherford's gold foil experiment provides experimental data. This data is used as evidence that atoms have most of their mass in a positive nucleus around which a smaller, low mass, oppositely charged particle accelerates.

From this data we develop our atomic theory.

The big bang will never be proven. It will always be a theory. You cannot [hopefully] create a test that will kick off a big bang. You cannot ever observe a big bag.

Other current theories, the knowledge of which may be limited to equipment, mathematics, and such may be proven in the future. However, you are asking for proof of an event. For this event there can be no proof, only evidence.

Gurgle

ScumLord wrote: »

On the surface of the balloon they should be speeding away from each other but moving in the same direction as each other away from the center of the explosion

Yes, and thats exactly whats happening.
But think from the point of view of one of those dots. You're moving away from the centre at the same speed and *almost* the same direction as your nearest neighbours so this common motion isn't visible to you.

As the surface expands, the space between you and your neighbour growing - so your neighbour is moving away from you.

The further away another galaxy is from ours, the faster it is receeding from us - and this makes sense when you consider that we too are moving away from the centre of the beginning of the universe.

rccaulfield

Yes we can see into the other side of the universe-oh and about 13 billion years back in time- use the search button!

Meh..all supernova spewing out matter are the equivalent of the big bang..hawking saw everything moving away from each other and concluded that at some point they must have been a single point..the universe has always existed, or rather, time is an illusion(one that lead hawking to his conclusion)..the universe just is..

ScumLord

Gurgle wrote: »

Yes, and thats exactly whats happening.
But think from the point of view of one of those dots. You're moving away from the centre at the same speed and *almost* the same direction as your nearest neighbours so this common motion isn't visible to you.

As the surface expands, the space between you and your neighbour growing - so your neighbour is moving away from you.

Shouldn't universes behind and in front of us be either stationary from our point of view or moving towards us? Every galaxy shouldn't be moving away from us or did you just mean in general most are? It just seems like a big leap to say there was an explosion when we've probably only seen a tiny portion of it.

Obviously the people who came up with the theory would know more than I do it's just not making sense in my brain at the moment. But that's happening with allot of theory's around now like the documentary I saw "is everything we know about the universe wrong" where dark energy, dark matter and dark flow just seemed to be quick fixes to massive holes in their theories.

Gurgle

ScumLord wrote: »

Shouldn't universes behind and in front of us be either stationary from our point of view or moving towards us? Every galaxy shouldn't be moving away from us or did you just mean in general most are? It just seems like a big leap to say there was an explosion when we've probably only seen a tiny portion of it.

There are no galaxies in front of or behind us. The ones closest are the ones that are moving away slowest

The Hill Billy

rccaulfield wrote: »

Yes we can see into the other side of the universe-oh and about 13 billion years back in time- use the search button!

That is only the size of the Observable Universe. Estimates that I have come across for the actual size range from 46.5 to 156 Billion Light Years.

OP - Check out this Cosmology FAQ. It may help.

Myrddin

Deleted User wrote: »

Meh..all supernova spewing out matter are the equivalent of the big bang..hawking saw everything moving away from each other and concluded that at some point they must have been a single point..the universe has always existed, or rather, time is an illusion(one that lead hawking to his conclusion)..the universe just is..

What has a Supernova got to do with an inflating singularity?
As far as I know, Hawking didnt postulate the theory...
The Universe has always existed? If so, why are galaxies moving apart? Why can heat from the supposed Big Bang still be detectable to us?
Time is an illusion? Why then, the faster an object travels does time pass at a different rate for the object, relative to a staionary object? Thats pretty tangible for an illusion...
The universe just is? Well thats me convinced.

Nobody knows what happened, its just the Big Bang model fits the available facts better than any other current theories. Since galaxies are moving apart, its logical that in the past that they were closer to each other. Dark Matter & Dark Energy were conceived to explain away some holes in the theory, which is incomplete. They may be correct, but we are a long way from proving their existence yet. We also cant unify our two universal models because they dont produce coherent results when tested together, maybe our macro & quantum theories are wrong, maybe they are not, but one thing is clear - we are still missing a big piece of the puzzle.

ScumLord

Gurgle wrote: »

There are no galaxies in front of or behind us.

So the balloon analogy, there's only galaxy's on the surface and there's nothing inside the balloon, Galaxies only exist in that one plane?

But there must be galaxies in front and behind (front being the direction we're heading away from the explosion) us because I can see them in every direction from earth.

Calibos

In terms of the balloon example there are no galaxies above the surface of the balloon nor inside it. The entire universe is the surface of the balloon. The mental gymnastics that the example requires of you is to take that 2 dimensional example and visualise it in terms of 3D space.

Say you are floating in space in a space suit and don't have to worry about looking down at your feet and the earth blocking your view. You are floating out in space on your own between the orbit of earth and Mars. All around you are stars. You can use your little jet pack to rotate in any direction you wish. Imagine each star you see is actually a Galaxy. Now picture the space between you and that galaxy expanding between. Neither you nor the galaxy are moving away from each other but you are getting further away from each other all the same because the space between you is getting wider. From your point of view, you are not moving and its the galaxy that you are looking at that is moving away from you., However from a guy in a spacesuit in the other galaxy, he is not moving and its you who is moving away from him.

When you look at any galaxy in the sky no matter what direction and they all seem to be moving directly away from you, it gives you the impression that you must be at the centre of the universe or the point of origin of the big bang. But we know the laws of physics are the same everywhere in the universe, so they must see the same thing. We can't both be at the centre of everything. The only thing that explains how all galaxies in all directions are moving directly away from us and how its the same everywhere in the universe is expanding space and the only thing that explains expanding space is a big bang.

BTW talking about the point of origin of the big bang is wrong anyway, Seeing as space didn't exist before the big bang(nor time so 'before' the big bang is wrong too),

20goto10

Scientists can go beyond what is visible to us or even beyond what is comprehensible by using mathematics (infinity is incomprehensible but even a 5 year old can do the maths to prove it - take the biggest number in the world and add 1 to it). The standard model shows that the universe started off as a singularity, exploded, cooled down and then started to expand (may not be entirely accurate but something along those lines). The problem is it is based on assumptions such as dark matter and dark energy, assumptions made to explain the unexplainable. So to answer your question, its a theory that is very much open to scrutiny and criticism even by experts in the field.

For example, the theory says the universe is 95% dark matter. That is the visible universe only makes up 5% of what we can actually detect. So obviously the question is, ok so what is dark matter. To which nobody has an asnwer. Yet it's a critical part of the standard model which says the universe came from the big bang.

In otherwords nobody knows, but its the best we have unless you prefer to believe in omnipotent beings.

Myrddin

The theory says that dark matter, is matter contained within galaxies that does not interact with normal matter. They only reckon its there because at the rate galaxies are spinning, based on our older model then the stars at the outer edge of the galaxy should be being flung off into space. So something is giving the galaxy more mass, enough to keep it gravitationally stable enough to be able to rotate those outer stars at the same speed as inner stars.

It does seem a rather convenient way of explaining the hole in the existing model I must admit.

rccaulfield

Hill Billy wrote: »

That is only the size of the Observable Universe. Estimates that I have come across for the actual size range from 46.5 to 156 Billion Light Years.

OP - Check out this Cosmology FAQ. It may help.

Yea the observable! tell me more!