# Big Bang Anybody? [duplicate]

I was recently watching a Discovery special on the Big Bang theory, and after a couple of drinks and a few detailed discussions with others, I have found that I do not believe the Big Bang ever happened. My reasoning is thus: no matter the precision in digressing the causation of material currently in our universe, a point arrives where the scientists give up (as far as I'm concerned) and say that the Big Bang happened out of nothing.

So . . . these scientists say that there was nothing, then the Big Bang happened, and then the scientists go on to explain the glories of the universe in detail without discussing how something came from nothing!

Here's my critique: if nothing is nothing, then there is no possibility of something coming from it, because there is nothing. I don't know how we came into existence, other than the possibility that the universe never had a beginning and has always been and is infinite, but that's why I'm asking the Mises community.

Any ideas?

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## marked as duplicate by Qmechanic♦, Ron Maimon, dmckee♦May 25 '12 at 19:26

It appears that you misunderstand (or at least mischaracterize) the position of scientists who accept the theory. There is a great deal of information on the Big Bang and if you come accross any that says definitively that there was "nothing" before it, you should probably check the reliability of your sources. Vote to close as not a real question. –  AdamRedwine May 25 '12 at 18:57
I think it's a real question so I wouldn't close it. I'll even attempt to answer it! –  John Rennie May 25 '12 at 19:00
Effectively a duplicate of physics.stackexchange.com/q/5150/520, physics.stackexchange.com/q/6919/520, and physics.stackexchange.com/q/7838/520, and physics.stackexchange.com/q/2355/520 which between them seem to address everything brought up here. It's not like this is the first time this has been brought up here. –  dmckee May 25 '12 at 19:06
Anyone have a preference about which of those is the best duplicate? (I know you want to answer it, @John, but answer one of the existing versions instead...) –  dmckee May 25 '12 at 19:08
big bang theory is famous, it's also widely misunderstood. A common misperception about the theory is that it describes the origin of the universe. That's not quite right. The big bang is an attempt to explain how the universe developed from a very tiny, dense state into what it is today. It doesn't attempt to explain what initiated the creation of the universe, or what came before the big bang or even what lies outside the universe –  Red Mar 10 '13 at 8:21

Science dismisses your entire question as meaningless, since there is no sense one can make of your statements:

• "if there is nothing, then nothing can come out!" How would you know?
• "scientists say there was nothing before the big bang" How would anyone know? What experiment could be done to give meaning to time before?

What scientists actually say is that it is only meaningful to speak of the big bang to the extend that it makes observational consequences for us today. Whenever you make a statement, try to define what you mean in terms of sense-experience. If you find that you can't, you are talking gibberish. This is called "positivism", and in positivism, one does not admit questions like yours as meaningful. Physicists are positivists.

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Obviously we can't see the Big Bang, and we can't make another Big Bang in our lab (ignore anyone who tells you that the LHC recreates the conditions of the Big Bang, because it doesn't). So what we do is to devise theories to explain why the universe looks the way it does, and then we do experiments to compare our theory with the real world. If the experiments match our predictions then we feel confident that our theory is correct.

In this case the theory we use to describe the universe is General Relativity. When we make a few simplifying assumptions about the universe and feed these into General Relativity it tells us that our universe is described by an equation called the FLRW metric. We've used this to make predictions about the universe, and so far they've all been proved true, so we think the FLRW metric really works.

The key prediction of our theory of the universe is the cosmic microwave background. The WMAP satellite has measured this to extreme accuracy and it perfectly matches what we'd expect.

The thing about the FLRW metric is that we can use it to wind time back and calculate how the universe must have been in the past. If we do this we find the universe gets denser and denser and hotter and hotter, until around 13.7 billion years ago the density and temperature become infinite. This is the point we've called the Big Bang.

The problem is that we can't do calculations when physical properties like density and temperature become infinite. That's because infinity isn't a number and you can't feed it into an equation. This means no-one knows what actually happened at the Big Bang. But we can get very close to it. In fact we can get to within 1 picosecond, that's $10^{-12}$ seconds after the Big Bang. That's how back the LHC takes us - to get any further back we'd need an even bigger accelerator, which i guess we'll build some day.

So when you say:

a point arrives where the scientists give up

well that's quite correct, and there's an excellent chance we'll never know exactly what happened at the moment of the Big Bang itself. However if we can calculate back to 1 picosecond after the Big Bang and get the right answers then you'd have to concede that if our theories tell us that the Big Bang happened then it probably did.

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The densities don't necessarily become infinite, rather you transition to inflation, and nobody knows how inflation happened exactly, because we don't know the inflaton. Also LHC produces local energies that would only have been produced previously at the big bang, and other colliders, like RHIC produce conditions that are even in something like a thermal equilibrium so that they are directly analogous to big-bang conditions. –  Ron Maimon May 26 '12 at 0:53