Tagged Questions
1
vote
2answers
92 views
Is it possible that universe might not be speeding up expansion?
I'm not sure but I was thinking of galaxies shrinking with time while still moving apart from each other at almost a constant speed or less (i.e: uniform/slightly decelerating expansion). This may ...
0
votes
0answers
72 views
Doubts about NASA's announcement of collision between Milky Way and Andromeda [closed]
Andromeda is one of the nearest big gallaxies out there.
We can estimate the distance to the Andromeda Galaxy measuring the apparent brightness of Cepheid variable stars; its distance is currently ...
1
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1answer
57 views
How is Doppler redshift of distant galaxies established?
Doppler redshift of distant galaxies gave first hint that the universe is expanding. I am curious to know how this redshift is actually measured and interpreted from observation. Suppose I observe ...
0
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0answers
90 views
Theoretical early-universe cosmology [closed]
I wanted to know what are the cutting edge/recent papers to read w.r.t theoretical early universe cosmology.
I would like to know of recent review papers
I would like to know of areas which use ...
4
votes
1answer
96 views
Polaris distance correction and implications for cosmological measurements
Polaris has been a guiding light of navigation for centuries. But Polaris also happens to be the closest cepheid variable to our sun. These, together with the type II-A supernovae constitute standard ...
5
votes
5answers
230 views
How is distance measured to far away stars and galaxies?
What I need is an accurate description of the methods used to determine the distance to Andromeda. The Parallax method is for nearby objects as I presume. The red shift method applies, but how do you ...
2
votes
1answer
92 views
Fractal Cosmology and Misner's Chaotic Cosmology
I have a question pertaining to the ideas behind the considered homogeneity and isotropic nature of the universe (at a grand scale) versus the theory of a chaotic and anisotropy structure of the ...
0
votes
2answers
67 views
A thought about Quasars
If Quasars are "beams" of energy exiting a super-massive black hole, in order for them to get through the black-hole's event horizon, they'd have to be traveling faster than the speed of light. My ...
3
votes
1answer
93 views
What would happen in the final days of the universe?
I would like to know the stages of how the universe would end and what would happen and what the possible scenarios are.
I understand that eventually all the stars would burn out and that would ...
2
votes
1answer
177 views
Light coming from distant galaxies
Some of the distant galaxies appear to be receding from us faster than the speed of light due to stretch of the space between us and those galaxies.
By an analogy with the ant on a rope paradox, the ...
10
votes
2answers
348 views
Can $10^{23}$ stars be treated with methods of statistical mechanics?
Statistical mechanics is used to describe systems with large number of particles ~$10^{23}$.
The observable universe contains between $10^{22}$ to $10^{24}$ stars. Can we treat those many stars as a ...
3
votes
3answers
353 views
What makes the earth keep spinning?
I am thinking of what makes the earth keep spinning. Is there anybody here know the answer?
2
votes
2answers
141 views
Was Sun a part of a binary system?
I've read that many stars and other celestial bodies are found to constitute binary systems where the two bodies spin around each other. But our Sun is one of the exceptions. Could it be possible that ...
0
votes
0answers
22 views
Expansion of Universe [duplicate]
Possible Duplicate:
Why space expansion affects matter?
If the Expansion is prevalent, i.e. it is observable and true then shouldn't that result in the expansion of the Milky Way galaxy, ...
4
votes
1answer
41 views
Is there any chance we could eventually observe the supernova of the first (Population III) stars
In an answer to my previous question about the first stars it was stated they probably formed at Z=20 to Z=60 and may have had a mass between tens to 100s to 1000s of times the mass of the Sun.
Given ...
12
votes
9answers
169 views
In astronomy what phenomena have theory predicted before observations?
As far as I know, astronomy is generally an observational science. We see something and then try to explain why it is happening. The one exception that I know of is black holes: first it was thought ...
7
votes
3answers
66 views
Are there any Earth-Meteorites on Earth?
A follow-on from this question, if meteorites can come from Mars, it seems they could have come from Earth and ended up back here (though I'm guessing that to be less likely). Do we have any evidence ...
8
votes
5answers
3k views
Stephen Hawking says universe can create itself from nothing, but how exactly?
Stephen Hawking says in his latest book The Grand Design that,
Because there is a law such as gravity, the universe can and will create itself from nothing.
Is it not circular logic? I mean, how ...
3
votes
1answer
10 views
Could asteroseismology have a significant potential to unravel the mechanisms of solar cycles that last thousands of years?
Could asteroseismology have a significant potential to unravel the mechanisms of solar cycles that last thousands of years?
And what about solar cycles 1 billion years ago and 2 billion years ago ...
1
vote
2answers
433 views
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 ...
3
votes
5answers
1k views
How do we know that earth moves around sun and that too in elliptical orbit
I know the basics of solar system like how earth moves around sun, and that we have so many planets, elliptical orbit of earth, and how far is sun from earth etc etc. I want to take a step back and ...
-2
votes
1answer
412 views
History of Man Acquired knowledge of solar system [closed]
I know the basics of solar system like how earth moves around sun, and that we have so many planets, elliptical orbit of earth, and how far is sun from earth etc etc. I want to take a step back and ...
