Questions tagged [hubble-constant]

Questions about the Hubble constant, the constant factor of the rate of expansion in the universe

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8
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2answers
3k views

Does the Hubble constant depend on redshift?

I know there are lot of questions on the Hubble constant already, but I am curious to know if it changes with redshift? If at current redshift, $z=0$, we know its value to be 0.7, will it be different ...
5
votes
4answers
1k views

So where are these measurements of galaxies moving faster than light?

https://physics.stackexchange.com/questions/400457/what-does-general-relativity-say-about-the-relative-velocities-of-objects-that-a "we can actually observe galaxies that are moving away from us at >...
0
votes
1answer
270 views

How strong is the gravitational stretch we experience from the edge of the universe?

How much gravitational effect do we experience (e.g. maybe -.00001 G or smaller) from the edge of the visible universe? By edge of the visible universe, I am talking about the region of the cosmic ...
5
votes
1answer
141 views

If we watched extremely red-shifted galaxies near the edge of the observable universe for a very long time, how would they change? Would more appear?

I have understanding sphere eversion as #1 on my bucket list (if I ever get a round tuit) but understanding metric expansion seems to be a rapidly receding possibility :-) Question: Suppose it takes ...
3
votes
1answer
769 views

Latest cosmological parameters

I'm looking for the latest values (with uncertainties) of the four main cosmological density parameters $\Omega_i$ : \begin{align}\tag{1} \Omega_{\text{mat}} &={} ?, &\Omega_{\text{rad}} &=...
7
votes
5answers
2k views

How is the Universe's Expansion Accelerating if the Hubble Constant is Decreasing?

I am just getting into the field of cosmology and was wondering what it means practically to say that the Hubble Constant is decreasing while the expansion rate of the Universe is accelerating. I am ...
5
votes
3answers
1k views

Does a merging massive binary black hole ‘emits’ more than one gravitational wave?

If we want to use gravitational waves (GW) to determine the Hubble constant, we need to find the source in the electromagnetic spectrum (EMS). However, we need to be lucky to ‘see’ it simultaneously ...
6
votes
1answer
476 views

Where can I find a database of galactic spectra?

I was wondering where spectra of galaxies at various redshifts are to be found. I'm looking for ones that can be used to find the recessional velocity of the galaxy and eventually the Hubble Constant. ...