Search Results
| Search type | Search syntax |
|---|---|
| Tags | [tag] |
| Exact | "words here" |
| Author |
user:1234 user:me (yours) |
| Score |
score:3 (3+) score:0 (none) |
| Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
| Views | views:250 |
| Code | code:"if (foo != bar)" |
| Sections |
title:apples body:"apples oranges" |
| URL | url:"*.example.com" |
| Saves | in:saves |
| Status |
closed:yes duplicate:no migrated:no wiki:no |
| Types |
is:question is:answer |
| Exclude |
-[tag] -apples |
| For more details on advanced search visit our help page | |
Results tagged with cosmology
Search options not deleted
user 298599
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.
0
votes
2
answers
314
views
Hubble parameter change in empty universe
According to the expression in the picture above, the Hubble parameter H(z) at time z is affected by the density distribution. In the empty universe, the density value is zero, and then the equation …
- 327
0
votes
0
answers
41
views
The distance to last scattering surface incerease?
The cosmic background radiation was released 38 million years after the Big Bang and is observed as the last scanning surface.
How does the distance to the last scattering surface differ when the obse …
- 327
1
vote
1
answer
70
views
Expansion velocity and recessional velocity
Differentiation of scale factors means the rate of expansion. But at the same time,
recession velocity has the following relationship: $\dot{𝑑}=\dot{𝑎}𝜒$
Do the recessional velocity and expansion v …
- 327
2
votes
1
answer
499
views
What is the scale factor $a(t)$?
Scale factors are used to refer to the velocity of expansion of the universe, curvature of the universe, etc.
Scale factors can be defined in the form $D(t)=a(t)D(t_o)$, meaning that scale factors can …
- 327
2
votes
0
answers
69
views
Does the cosmological redshift of the same object has a same value as it evolves
https://arxiv.org/abs/1802.02444
According to the link above, the following phrase comes out:
" One must keep in mind that in the real universe, the same object( or comoving position) does not take di …
- 327
2
votes
1
answer
779
views
Is Hubble graph straight line or curve?
According to this paper, the graph explaining Hubble's law is expressed in two cases. The first is when the hubble parameter is constant over time, and the second is when it changes over time.
My qu …
- 327
0
votes
0
answers
50
views
How to explain the accelerated expansion universe
enter image description here
Some textbooks describe accelerated expansion with an H value, as shown in the two figure above. It is said that the H value is accelerated because it is smaller in the p …
- 327
1
vote
0
answers
154
views
Explain Hubble's law using proper distance and comoving distance
As far as I can understand, Hubble's law has the form of V(to)=HoDo at a close distance. The meaning of this equation is as follows.
For example, when z=0.01, the emitted photons arrive at us and tel …
- 327
1
vote
0
answers
111
views
Korean SAT question error: Hubble law
I brought some of the questions from the Korean SAT. In the context of Hubble's law, galaxies A, B, and C appear like pictures. (The $y$-axis is the recessional speed, and the $x$-axis is the distan …
- 327
1
vote
1
answer
82
views
Is the cosmological Doppler effect more effective at long wavelengths?
When observing the Doppler effect of a particular galaxy, is the wavelength change greater for long wavelengths?
According to the simple Doppler effect formula, the wavelength change is proportional t …
- 327
0
votes
1
answer
113
views
Why does starting point of graph differ?
Why open universe, flat universe, closed universe have a different starting point?
I know they have different age.
I want the solution using mathematical method
- 327
1
vote
2
answers
173
views
Kinematic behavior of a flat, a closed, an open universe
according to An Introduction to Modern Astrophysics, 1263p, there is explanation about evolution of scale factor.
“ For the early universe($R<1$) there is little difference among the kinematic behav …
- 327
0
votes
1
answer
227
views
Redshift graph of Type Ia supernova: Two case
The redshift graph obtained from a well-known supernova study appears in two cases in Google search.
When I find the relevant data, regardless of whether the y-axis is set to distance or grade, the …
- 327
4
votes
1
answer
421
views
Redshift of the Cosmic Microwave Background: increasing or decreasing?
$$\dot z\equiv\frac{\mathrm d z}{\mathrm d t_{\text{obs}}}(t_0)=(1+z)H_0-H(z)$$
The picture and equation above are quoted from Liske et al. (2008).
According to the equation, the redshift of the cosm …
- 327
-1
votes
2
answers
246
views
What is the meaning of $O(10^{-14})$?
What is the meaning of the symbol,O(1),O(10^-4),in the picture above the text box?
I am not a computer engineer or a computer language major.
Please tell me simply. I don't want an explanation with …
- 327