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Mar
16
comment What do cosmologists mean when they talk about “the running of the spectral index”?
Why are the fluctuations called scale invariant only if $n_s = 1$? In other contexts, power spectra are called scale invariant if the exponent of k takes any constant value ...
Oct
26
awarded  Taxonomist
Sep
25
awarded  Yearling
Sep
24
awarded  Autobiographer
Aug
25
comment Will an observer falling into a black hole be able to witness any future events in the universe outside the black hole?
The only people who are still confused about the difference between coordinate and true singularities are at most beginning students. So it is not clear about who s confusion the first sentence talkes about; working physicists can not be meant.
Jul
2
awarded  Curious
May
26
awarded  Nice Question
May
24
awarded  Custodian
May
24
reviewed Approve How exactly does inflation convert random gravity fluctuations into coherent gravitational waves?
May
3
asked How exactly can the hypothetical conformal invariance of the CMB spectrum be established by analyzing tensor modes?
Apr
21
comment What does black hole evaporation correspond to in the accelerating universe / black hole analogy?
Dear downvoter, what is wrong with my question, can you please be a bit more specific and explicit thant just pushing the button ?
Mar
31
revised How exactly does inflation convert random gravity fluctuations into coherent gravitational waves?
Improved title (I hope so)
Mar
26
asked Does the holographic principle contradict eternal inflation?
Mar
24
accepted Do the E and B modes of the CMB polarization have anything to do with electric and magnetic fields?
Mar
24
asked How exactly does inflation convert random gravity fluctuations into coherent gravitational waves?
Mar
23
comment Do the E and B modes of the CMB polarization have anything to do with electric and magnetic fields?
Thanks for this nice answer and claritication, I have already seen such a picture for example from the press announcement :-). What always looks slightly strange to me is, that it seems that in the pattern for $E>0$ it looks from a naive point of view that if the lines are $\vec{u}$ then $\nabla\vec{u} = 0$ than positive ... Can you give more details about how gravitational waves can produce temperature quadrupoles and generally about the mechanism 2 ?
Mar
18
comment Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves?
@Py-ser it was mentioned somewhere in a physics blog and I am looking for papers or direct explanations (in an answer) that explain it further.
Mar
17
asked Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves?
Mar
16
revised Do the E and B modes of the CMB polarization have anything to do with electric and magnetic fields?
Added source of information
Mar
15
asked Do the E and B modes of the CMB polarization have anything to do with electric and magnetic fields?