All Questions
Tagged with cosmology experimental-physics
62
questions
81
votes
6
answers
7k
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What was the major discovery on gravitational waves made March 17th, 2014, in the BICEP2 experiment?
The Harvard-Smithsonian Centre for Astrophysics held a press conference today to announce a major discovery relating to gravitational waves. What was their announcement, and what are the implications?
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- 5,569
41
votes
5
answers
13k
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Is light actually faster than what our present measurements tell us?
It is well established that the light speed in a perfect vacuum is roughly $3\times 10^8 \:\rm m/s$. But it is also known that outer space is not a perfect vacuum, but a hard vacuum. So, is the speed ...
user182521
29
votes
3
answers
10k
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How do people calculate proportions of dark matter, dark energy and baryonic matter of the universe?
The Wikipedia page on dark matter mentions that the Planck mission had revealed that in our universe ordinary baryonic matter, dark matter and dark energy are present in the ratio: 4.9%, 26.8% and 68....
- 1,057
22
votes
5
answers
1k
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What experiments, other than Hubble Expansion, support the Dark Energy theory?
Dark energy is introduced as a constant inside Einstein's equations. Its primary purpose, from what I understand, is to make Einstein's equations compatible with the accelerating expansion of the ...
- 5,071
20
votes
3
answers
8k
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Why do neutrino oscillations imply nonzero neutrino masses?
Neutrinos can pass from one family to another (that is, change in flavor) in a process known as neutrino oscillation. The oscillation between the different families occurs randomly, and the likelihood ...
- 1,516
17
votes
9
answers
17k
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What is the difference between translation and rotation?
What is the difference between translation and rotation ?
If this were a mathematics site, the question would be at best naive.
But this is physics site, and the question must be interpreted as a
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- 3,798
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
16
votes
3
answers
1k
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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
11
votes
1
answer
700
views
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
10
votes
4
answers
1k
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Experimental evidence for parallel universes/multiverses
My idea of physics is that it is a collection of mathematical laws relating observables. And that one can perform alot of mathematical derivations on these laws to produce new laws between observables....
- 101
9
votes
1
answer
1k
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What are the different ways to measure the spatial curvature of the universe?
Just what the question asks. Assuming the Friedmann-Rovertson-Walker (FRW) metric, what measurements can be performed to determine the spatial curvature of the universe.
- 3,492
9
votes
6
answers
4k
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What is the evidence for Inflation of the early universe?
The theory of Inflation explains the apparent consistency of the universe by proposing that the early universe grew exponentially for a 1E-36 seconds. Isn't a simpler explanation that the universe is ...
- 415
8
votes
2
answers
1k
views
Compactness of spacetime: experiment and math
It is common to find models built on a compact spacetime. In mathematics, compactness is a very nice property $-$ and lot of powerful results depend on it.
But
how safe is assuming compactness of ...
- 1,544
7
votes
2
answers
659
views
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
7
votes
2
answers
561
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What's the significance of large-scale anomalies in CMB
What's the significance of large-scale anomalies in CMB that are confirmed by Planck? I've read somewhere that the cold spots can provide support for string theory or it may be due to a parallel ...
- 71