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Dec
18
awarded  Yearling
Nov
22
answered How can an infinite universe expand?
Oct
19
comment What were the 2 satellites I saw this morning?
I'm voting to close this question as off-topic because not about astronomy
Oct
19
comment What were the 2 satellites I saw this morning?
Almost certainly not astronomical objects.
Oct
19
comment Is the time lapse considered when estimating the age of the universe?
Which time-lapse are you referring to?
Oct
18
awarded  Revival
Oct
16
comment Two species of dark matter?
@RobJeffries I'm particularly concerned about the waste of brain, of which comparatively little is spend in the dark-matter 'industry'.
Oct
16
comment Two species of dark matter?
@RobJeffries thanks for your comment. I'm fully aware that dark matter is only still a hypothesis and hinges on the correctness of GR, which in turn is not experimentally verified on the relevant field strengths (or shall I say 'weakness'). The cuspiness issue is not a fundamental problem, as its prediction ignores baryonic effects, which must play a role on small scales. Moreover, on galaxy-cluster scales, the cusps are there (the mass profile in the outer parts of central-cluster galaxies is what we expect for the inner parts of the cluster halo).
Oct
15
comment Two species of dark matter?
@AlexeyBobrick There is zero evidence for supersymmetry. AFAIK, supersymmetry has not made a single falsifiable prediction that was later verified. Supersymmetry is a classiacal WOMBAT (= Waste Of (tax payer's) Money, Brain, And Time).
Oct
15
revised Two species of dark matter?
added 12 characters in body
Oct
14
revised Two species of dark matter?
added 208 characters in body
Oct
14
comment Two species of dark matter?
Would the downvoters please indicate what I could improve with this answer and/or why it's not useful?
Oct
8
comment Could there be dark matter black holes?
@questionhang As I've said 'since DM cannot lose its excess energy and angular momentum as easily as gas'. It can only lose it via gravitational interactions (with anything), but that is very inefficient.
Oct
6
comment What will happen to life on Earth when the Andromeda and Milky Way galaxies collide?
I was not asking for a comment, but for improvement to your answer, and I was not asking because I doubted it, but to give you a chance to improve your answer (though I was a bit surprised at the time scale of only 1Gyr).
Oct
5
comment What will happen to life on Earth when the Andromeda and Milky Way galaxies collide?
The only remotely sensible answer here.
Oct
5
comment What will happen to life on Earth when the Andromeda and Milky Way galaxies collide?
You should provide evidence (via links to respectable sources) for your claims that in 1-2 billion years water on Earth will be evaporated.
Oct
5
comment What will happen to life on Earth when the Andromeda and Milky Way galaxies collide?
Why do you assume that any humans or even any observing life forms will be around on Earth in 4billion years?
Oct
5
comment When will all eight planets in our solar system align?
Ignoring [...] interference from any bodies [...] interfering with their orbits -- this obviously includes the Sun, and without the Sun, the planets orbits are not well defined. Hence your question is unclear.
Oct
5
answered When will all eight planets in our solar system align?
Oct
5
comment When will all eight planets in our solar system align?
There are several blunders in this answer. First, using all digits in your tables (which implies converting to centidgrees and centidays) I actually get $x\approx1.698\times10^{42}$ (from the same online tool), which amounts to $1.29\times10^{33}$yr. I don't know how you obtained the lower value, but I strongly suspect you omited some digits. Secondly this shows that when adding more digits the solution tends to infinity: the correct answer is: radial alignment never occurs. Finally, assuming that the planets' orbits are following this simple motion is just wrong.