All Questions
Tagged with astrophysics hubble-constant
8
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What exactly does $k\sigma$ mean in astrophysics and cosmology?
In statistics, $\sigma$ or $1\sigma$ is the standard deviation. For the normal distribution, approximately $68\%$ of the values lie within $1\sigma$ range, $95\%$ within $2\sigma$, and $99.7\%$ within ...
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Would we know if the universe was rotating?
I was wondering what we would observe if the universe had a small rotation. My conclusion was that galaxies on the equatorial plane of the universe would be slightly more redshifted than galaxies than ...
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-2
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Why is v lowercase and D uppercase in $v=H_0D$?
Why is v almost always written in lowercase and D in uppercase in $v=H_0D$?
OK, v is in lowercase, as usual, but then why is D in uppercase? What's so different/special about it?
In my physics school ...
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How can Hubble's original data show that the universe is expanding?
The diagram from Hubble's original data only goes from 0 to 2 Mpc (see here), and yet our Local Group is not supposed to be expanding and it is 1.5 Mpc in radius. How can the data show that the ...
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Since the Hubble Constant changes over time (it's a variable parameter), why can't the conflicting values of 67.4 and 73 both be right?
Are the conflicting values from the 'early universe' (Planck) method and the 'late universe' (Distance ladder) method actually compatible? Since during the latter period of the universe 'dark energy' ...
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What exactly is the estimated distance to a far-off object when they say '50 Mpc/h' or '50 Mpc h^-1'? Is it less than 50 Mpc? Do you ÷ by 67 or 74?
Several recent arxiv.org papers I read mention distances to very distant objects in Mpc (megaparsecs) divided by Hubble's 'constant'....
Does that mean we should divide the Mpc or Gpc (gigaparsecs) by ...
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14
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How is the Hubble constant determined from gravitational waves?
We know there is a discrepancy between measurements of the Hubble constant, $H_0$. On one side there is the method of the Planck mission, where they use the CMB and the $\Lambda$CDM model to determine ...
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Why the Hubble constant is so inconsistent?
Having a look on Wikipedia I noticed the following values (of the last 6 years) for the Hubble constant:
67.6±0.7 SDSS-III Baryon Oscillation Spectroscopic Survey
73.00±1.75 Hubble Space ...
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