All Questions
Tagged with cosmology experimental-physics
62
questions
5
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1
answer
152
views
What are some experimental verification of the non-linearity of gravitation?
According to my (limited) knowledge, all experiments to date probe only situations which can be understood using the linearized version of general relativity. For example, measuring gravitational ...
- 2,568
16
votes
2
answers
3k
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What evidence do we have that CMB is the result of the Big bang?
I got the main picture repeated over and over again about why if there's a Big bang we indeed should see the CMB with this feature. In this question I'm asking something different: what independent ...
- 944
3
votes
1
answer
77
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Running Constant Values At Very Low Temperatures
From Wikipedia Coupling Constants, using QED as an example. I realise that the one-loop beta function in quantum chromodynamics is negative.
If a beta function is positive, the corresponding ...
user108787
2
votes
0
answers
59
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Any method to determine the gravitational constant $G$ from observations in cosmological scale?
By the observations in cosmological scale, I mean observations by astrophysicists like motions of quasars in far distance from us, relative motions of our galaxy to others, etc.
I know the famous ...
- 189
3
votes
1
answer
133
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How was hydrogen gas (H) obtained by spectroscopists? Why is there more H than H2 in space?
Introductory quantum mechanics lessons talk about emission and absorption spectra for the hydrogen gas, and then give you an explanation as if this gas were pure $H$ atoms, and not the $H_2$ molecule (...
- 1,619
3
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1
answer
1k
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Is there any evidence against the Cosmological Principle?
I have been slowly getting more into math, but haven't gone into differential geometry or anything like that yet, so this question might be basic. Trying to get a deeper understanding of the ...
- 2,200
3
votes
1
answer
147
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The actual space curvature
What is the curvature of our physical space, according to the latest experimental data? I've found it somewhat difficult to find a definitive answer to the question, because the spacetime curvature ...
- 33
2
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1
answer
236
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How do we get the power spectrum through the CMB?
How do we get the power spectrum through observing the CMB?
- 11
3
votes
5
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4k
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Where does General Relativity (GR) fail experimentally? Experimental shortcomings of GR?
When speaking with researchers and professors at my physics department, I sometime catch this undertone in the conversation when speaking about GR: almost as if some are not entirely convinced about ...
- 3,719
11
votes
1
answer
700
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The status of the BICEP2 'discovery' after Planck 2014
The tumultous period after the original announcement that the BICEP2 experiment had supposedly detected strong evidence of cosmological inflation in the form of B-mode polarization in the cosmic ...
- 16.4k
16
votes
3
answers
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What is the most compelling evidence of General Relativity in the presence of matter and energy?
The most oft-cited triumphs of GR are things such as the shifting perihelion of Mercury, gravitational redshift experiments, and gravitational lensing. But, as far as I know, these are only ...
- 2,046
1
vote
1
answer
82
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Data/signal from a black hole to observe a singularity
I wonder if a situation is possible where, we measure some signal/property concerning a black hole. Supposing the measurement we make with some telescope, gets us the Fourier transform coefficients of ...
- 2,152
2
votes
2
answers
177
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How do we observe the expansion of the universe?
This is my first question.
So I was reading about expansion of the universe and from what I've seen, the only way that we know that universe is expanding is by measuring redshift.
Also, here it says ...
- 31
2
votes
4
answers
339
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What experiment would disprove Friedmann model of cosmology?
What experiment would disprove Friedmann model of cosmology?
As a layman, I have read a lot of articles and threads in specialized forums. I am probably wrong, but I developed an impression that that ...
- 5,854
7
votes
2
answers
659
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What experiments compete with BICEP 2, and when are their results expected?
The recent results of the BICEP 2 experiment published on March 17th 2014, has generated a lot of media attention, with the general consensus being that "this is a major discovery" perhaps leading to ...
- 3,108