Is Red Shift enough to justify an expanding Universe?

Question

Is the expanding universe theory based on nothing more than Red Shift - or is there some other evidence for it.

Or are we just saying it can't be anything else?

Answer 1

What if the redshift occurs due to the passage of time itself as well as any differences in velocity? We may be in a steady state universe.

Answer 2

The Red Shift, discovered by Hubble in the 1920s, is enough to support the claim that the observable universe (as we look back in time) is expanding .

Now, to get that data, Hubble had to use "standard candles" such as Cepheid variables, RR Lyrae stars, etc., to get his distances, so they have to behave properly everywhere.

If that's so (and all more recent data tends to confirm), then the recession speed of stars & galaxies increases linearly as the distance from us increases.

That justifies the expanding universe notion.

The next step is to look backward in time. If the universe is expanding now, then it must have been smaller before. It's that thinking that leads to the Big Bang theory.

There are some glitches in here, mostly involving gravity. If the universe is expanding, is the rate of expansion increasing or decreasing? That depends on the total amount of matter in the universe, plus any mysterious "dark matter" we can't detect, any "antimatter", or anything such as "anti-gravity" that will speed up the expansion.

So the expanding universe theory starts with Red Shift, but has to take other things into account as well.

Answer 3

There are more components for the explanation, just Red Shift is the most easily explainable. The other is the Cosmic Microwave Background, the patterns observed in it would fit an expansion model originating from a big bang.

Answer 4

Skepticism is always a healthy aspect of science. Good for you!

I think your question should be approached as much from simple logic as from any involved science.

(1) The feature of light commonly known as "redshift" has been completely verified. It is valid. The light from almost all distant celestial structures exhibit a redshift. The farther away such an object is the more pronounced is its redshift. This distance-to-redshift-relationship is consistent.

(2) If the assumption is correct that our universe was once in a super-dense condition, then the condition of the universe we observe today most likely comes from expansion.

It seems to me that if science were to discard the principle of redshifted light for determining universal expansion, then science would also have to do one of two things -- (a)find another tool to measure cosmic expansion; (b)totally deny cosmic expansion

Answer 5

I'm aware that there are other reasons to justify the BB ergo expanding universe theory. I'm no expert but i believe there is something to do with microwaves emitted by the BB still being received today.... perhaps someone could elaborate?

Answer 6

I'm not sure if there is but red shift as we know means something is moving away and that has been proved. Try reading 'A brief history of time' by Stephen Hawking

Answer 7

Reading between the lines I find a kindred spirit - it never really convinced me either. I think it is pretentious in the extreme to think that we know the total facts behind the physics involved throughout our universe - we are probably just scratching the surface of knowledge.

Answer 8

Red shift would support it, but you need other data as well. It's just one component

Answer 9

No, it is not enough. Both shifts are responsible