The study of the large-scale structure, history, and future of the universe. Cosmology is about asking and answering questions about the "big picture" - the extent, origin, and fate of everything we know.

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6
votes
2answers
250 views

Does the recent re-count of stars in elliptical gallaxies affect our understanding of the universal mass balance?

I've seen several popular reports of a new count of low-mass stars in elliptical galaxies (here's one). Edit: Pursuant to several correct comments I've changed the title to agree with the actual ...
26
votes
5answers
2k views

Could gravity be an emergent property of nature?

Sorry if this question is naive. It is just a curiosity that I have. Are there theoretical or experimental reasons why gravity should not be an emergent property of nature? Assume a standard model ...
5
votes
3answers
752 views

Big bang and time

I heard Carl Sagan talking about the Universe 15 Billion years ago, and the Big Bang. He made the statement that it was the biggest explosion of all time (at first I thought this a subtle pun). This ...
29
votes
5answers
4k views

What if the universe is rotating as a whole?

Suppose in the milliseconds after the big bang the cosmic egg had aquired some large angular momentum. As it expanded, keeping the momentum constant (not external forces) the rate of rotation would ...
5
votes
5answers
3k views

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 ...
21
votes
6answers
2k views

Why isn't dark matter just matter?

There's more gravitational force in our galaxy (and others) than can be explained by counting stars. So why not lots of dark planetery systems (ie without stars) ? Why must we assume some undiscovered ...
-5
votes
1answer
357 views

Why is there something rather than nothing? [closed]

Why is there something rather than nothing? And before you answer "God did it," consider Carl Sagan's reply "then how did God come about?"
3
votes
1answer
372 views

Possibly naive question about quantized space-time

I beg your pardon in advance if this question is naive. In Quantum Mechanics, discrete values of measurements occur only in relation to bound states. This is because of the general solution for the ...
10
votes
10answers
2k views

What is the most efficient way to destroy the universe? [closed]

Don't worry... I won't actually do it, just would like to know how.
11
votes
1answer
372 views

How many atoms per light year does light encounter when traversing interstellar space?

Interstellar space is pretty empty but there a small number of of atoms (mostly hydrogen?) floating around. How many atoms per light year would a photon encounter while traversing interstellar space?
7
votes
4answers
839 views

Nature of decoupling of matter and radiation

I have a question about cosmology. At popular level people explain the time of decoupling of matter and radiation as the moment when temperature falls enough for nuclei and electrons to recombine into ...
8
votes
3answers
495 views

What current alternatives are there to the standard concordance model of cosmology?

The current "standard model" or concordance model of cosmology is Lambda CDM which includes late time acceleration due to a cosmological constant, cold dark matter as the missing matter component and ...