Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 28/09/2016 13:23:01

Title: Does the expanding universe prove that dark matter existed before the big bang?
Post by: thedoc on 28/09/2016 13:23:01

David asked the Naked Scientists:
   If the Universe (space and matter) is expanding and accellerating faster the greater distance you are from the known limits of the Universe. My question(s) is:-

Does the expanding Universe prove that dark matter existed before the big bang?........and.........

If the Universe is expanding, what has created the space in the first place to allow space and time to expand within it (chicken and egg scenario lol)?
What do you think?

Title: Re: Does the expanding universe prove that dark matter existed before the big bang?
Post by: Bill S on 30/09/2016 21:25:19

Hi David; I'm certainly not an expert, so question everything I say. [:)]

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If the Universe (space and matter) is expanding and accellerating faster the greater distance you are from the known limits of the Universe.

My understanding is that there are limits to our knowledge of the Universe, but we don't what, if any, limits the Universe might have.

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Does the expanding Universe prove that dark matter existed before the big bang?

I don't see why it would prove that, but possibly you have thought of something I have not.

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If the Universe is expanding, what has created the space in the first place to allow space and time to expand within it

Informed opinion seems to be that there was probably no pre-existing space and time.  Time and space were created with, and expand with, the Universe.

Title: Re: Does the expanding universe prove that dark matter existed before the big bang?
Post by: evan_au on 30/09/2016 22:58:18

Quote from: David

Does the expanding Universe prove that dark matter existed before the big bang?

We don't really know what dark matter is, or what its properties are - but we see the effects of its gravity.

The effect of this gravity is to slow down the expansion of the universe.

Observations show that the universe is expanding, and is expanding at an accelerating rate. This is the opposite of the effect you expect from dark matter.

So dark energy (another unknown) has been suggested as the driver for the accelerating expansion of the universe.

Perhaps this implies that (pent-up) dark energy existed before the big bang, but I don't see how it suggests the existence of dark matter before the big bang.