All Questions
73
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Was "flow of time" equally fast during the life of universe? Is Doppler Effect the only interpretation of "shift to red"? [duplicate]
I'm an IT developer and recently I created a project where I tried to send signals between two threads in a slowing down environment. I simulated two points with their own clocks and tried to send a ...
- 101
4
votes
1
answer
675
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Intuitive explanation of COSMIC TIME?
I came across the following statement, while studying a Newtonian model for cosmic expansion:
"If $R(t)$ is the scaling factor, we can define the Hubble parameter as $H(t)=\frac{\dot{R(t)}}{R(t)}...
- 152
1
vote
1
answer
95
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What happens if we let time expand in the FLRW metric?
If we multiplied the time differential (dt) by a scale factor that depends on time in the FLRW metric, what would this imply on cosmology? In particular, what are its implications on the cosmological ...
- 468
9
votes
2
answers
1k
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Has the age of the universe changed in 2023?
I teach high school physics and physical science. I was going through the definitions of theory and law when a couple of my students (of different periods) asked about some recent development that ...
- 203
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48
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Time from big bang to here [duplicate]
New to this so apologies for my ignorance, the simpler the answer the better. Here goes.
Light took 13.5 billion years to get to us from the big bang.
On an imaginary neighboring planet that is much ...
-1
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1
answer
104
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If Inflation never happened before the CMB, and the present expansion were projected backwards, how old would the Universe be since the Big Bang?
The Cosmic Microwave Background Radiation is the oldest thing we can directly observe. To explain the near uniformity of temperature of the CMBR and the flatness of space, Cosmic Inflation was ...
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1
vote
3
answers
279
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Can the age of the universe actually be calculated through Hubble's constant?
I was reading a high-school physics textbook, and it stated that the age of the universe is equal to 1 / Hubble's constant. They even give a derivation: $v = H_{0} D$ and $D = vt$, so subbing in gives ...
- 25
2
votes
1
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131
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Why is cosmological time unique?
According to the definition I have encountered for the concept of cosmological time, it is defined in the following way:
The cosmological principle states that, at each location in the universe, it ...
- 293
-1
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1
answer
77
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Could an observer in time determine whether time had no beginning or had a beginning infinitely long ago? [closed]
I don't know if this is more a question for mathematicians or physicists (or even philosophers), but what would be the difference between time having a beginning infinitely long ago and time having no ...
0
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2
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453
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Calculation of age of Universe
The age of the Universe is about 13.8 billion years, measured by light emitted from the time it emerged from opaqueness. But how was the time from the "beginning" to 380,000 years (era of ...
- 303
3
votes
1
answer
236
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Deriving the age of the universe
I am trying to work out the solution to exercise 8.4 from An Introduction to Modern Cosmology by Andrew Liddle. I could derive the Friedmann equation as below,
$$\dot{a}^2 = H_0^2 \left[\Omega_0a^{-1} ...
1
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2
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153
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Can the age of the universe be much bigger than 13.8 billion
If observable universe is only a small fraction of the existing universe, does it imply that the age of the universe is much more than 13.8 billion years or the expansion of the universe is much ...
- 57
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0
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44
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If the universe is 13,7 billion years old how it could be infinitely large? [duplicate]
If the universe is 13,7 billion years old how it could be infinitely large? Maybe it is curved to account for being finite? But then there should be more spatial dimensions...is it right?
- 1,815
6
votes
3
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543
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To what precision can we determine the age of the universe theoretically?
Does it makes sense to expect/hope that one day we will measure the age of the universe (in Earth's frame of reference for example) much more precisely, down to sub-year precision? Is there an ...
user86478
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Is the Big Bang occurring or did it already occur (a question about time) [duplicate]
I understand how time (space/time) is perceived according to the theories of relativity, but I still don’t understand:
Did the Big Bang occur 13.8 billion years ago or is it occurring relative to us ...
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