The cosmological-constant tag has no wiki summary.
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de Sitter versus Minkowski QFT and cosmological constant
WMAP/Planck results confirm than we live in a de Sitter-like phase, i.e., a Universe with positive acceleration or positive cosmological constant! Therefore, I believe that a way to solve the ...
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Cosmological triangle with PLANCK results
Is there an updated version of the cosmological triangle with recent PLANCK results included?
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Cosmological constant
I have always wondered about how cosmological constant is characterized. So since it is still a hypothesis you often read the “cosmological constant measured to be ….”. Shouldn't the statement read ...
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Has unnaturalness motivated new ideas in physics?
The cosmological constant problem arises because the natural scale of the cosmological constant is $10^{120}$ times larger than what we observe. This implies that the dimensionless constant is much ...
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Is antigravity the source of accelerating expansion (dark energy)?
Is antigravity the source of accelerating expansion(dark energy)?
From the observation of 1998, we found that our universe has been continuing accelerating expansion, and the unknown cause for this ...
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Black hole accretion of dark energy
Dark energy physically can be interpreted as either a fluid with positive mass but pressure the negative of its density (pressure has units of energy/volume, and energy is mass), or a property of ...
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How many physical constants should there be?
I see there are different accounts on the number of physical constants. Is there any theory predicting what the number of physical constants is? I agree there should be at least one but I have no ...
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Why is it desirable to have a symmetry to make cosmological constant zero?
It is sometimes stated that absence of a symmetry to make cosmological constant zero is a problem. But observed value of dark energy is very small and non-zero. So why is it desirable to have a ...
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Vacuum energy and perpetual motion
The part of the Einstein equations of general relativity referred to vacuum energy, introduce a repulsive term in gravity. This means that as the space become bigger and bigger, vacuum part become ...
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What are the differences between dark energy and a cosmological constant?
My possibly mistaken understanding is that dark energy changes with time, whereas a cosmological constant is, well, constant. What about gravitational clumping? Detecting relative motion?
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Cosmological constant of standard model of cosmology and observational data
I am curious whether the current Lambda-CDM model of cosmology matches well with observational data, especially expansion of the universe.
How well does Lambda-CDM defend its established status from ...
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Higgs field requires a large cosmological constant — does the Zero Point Field balance it?
I just read Wolfram's blog post on the Higgs discovery.
Still, there’s another problem. To get the observed particle masses,
the background Higgs field that exists throughout the universe has to
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extracting energy from cosmological expansion
This question is a more concrete reincarnation of an old question about energy conservation in GR.
Are there mechanisms to extract energy from the cosmic rate of expansion? putting some extremely ...
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If space is being doubled, how fast is it doubling? [duplicate]
Possible Duplicate:
How long does it take for expanding space to double in size
According to the standard concordence model, I heard that it's likely that space is doubled after 11.4 ...
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How is causal patch complementarity compatible with behavior during inflation?
Causal patch complementarity is the conjecture that in de Sitter space with a positive cosmological constant, the states within the causal patch are sufficient to fully describe the universe with the ...
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Interplay between the cosmological constant and “microscopic” properties of string vacua
As far as I understand, string phenomenology is usually concerned with compactifications of string theory, M-theory or F-theory in which the uncompactified dimensions form a 4-dimensional Minkowski ...
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Are there stable string theory vacua with non-minimal cosmological constant?
Naive reasoning suggests that a string theory vacuum with cosmological constant Lambda1 is always unstable as long as there is a string theory vacuum with cosmological constant Lambda2 < Lambda1 ...
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Does anisotropic expansion of the universe imply quintaessence?
a Recent paper establishes under solid grounds anisotropy in the expansion acceleration rate in the universe. My question is very simple:
can this anomaly be explained entirely in terms of a ...
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Vacuum and repulsive gravity
How can one show from General Relativity that gravity is attractive force, and under which conditions it becomes repulsive, also why positive energy vacuum drives repulsive gravity?
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Do the laws of physics evolve?
Hubble's constant $a(t)$ appears to be changing over time. The fine stucture constant $\alpha$, like many others in QFT, is a running constant that varies, proportional to energy being used to measure ...
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What is meant by positive and negative gravity/energy/spactimecurvature?
I have recently come across some cosmological assertions (based on empirical data) about the universe being self contained in the sense that it is entirely capable of coming into existence from a ...
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Why didn't Newton have a cosmological constant
Einstein initially added the Cosmological Constant because (if I get this right) it seemed to him that the universe should be static. I agree that back then this would have been an obvious assumption. ...
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Are modified theories of gravity credible?
I'm a statistician with a little training in physics and would just like to know the general consensus on a few things.
I'm reading a book by John Moffat which basically tries to state how GR makes ...
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Strings with negative pressure
This question is inspired by the following comment:
the strings in string theory are relativistic and on a large enough piece of world sheet, the internal SO(1,1) Lorentz symmetry is preserved. ...
