All Questions
15
questions
-6
votes
1
answer
97
views
What exists in the world according to the special relativity? [closed]
Before I learned about special relativity, I thought that only one 3-dimensional state of the world exists. Then, like in game of chess, in one "turn" previous state is destroyed - and the ...
1
vote
1
answer
149
views
Is there a way to view Einstein's spacetime "from outside" to intuitively understand it?
Is there a way, in Einstein's relativity (special and general) to view spacetime from a point of view that sits "outside" of it, to intuitively understand it?
We humans can only see 3 ...
- 107
2
votes
0
answers
50
views
Does shape dynamics introduce a temporal order on events separated by a space-like interval such that their simultaneity is not relative?
I've read some popular books and articles that reference shape dynamics (e.g., The Singular Universe and the Reality of Time, https://www.pbs.org/wgbh/nova/article/shape-dynamics/). I have also ...
- 181
2
votes
0
answers
48
views
Does expansion of space over time assume a particular space/time dichotomy?
Regarding the expansion of the Universe, Wikipedia states:
The expansion of the universe is the increase in distance between any two given gravitationally unbound parts of the observable universe ...
- 222
2
votes
3
answers
218
views
Does our past light-cone have some extension in three-dimensional space?
On spacetime diagrams cosmologists represent our past light-cone as a two-dimensional surface extending back in time, on which are situated all light-emitting events which we can observe today. This ...
- 928
1
vote
1
answer
155
views
Lower limit to the distance between two mouths of a wormhole?
This is more like a conceptual question. Wormholes are tunnels connecting two different parts of the same universe or connecting two parts in different universes. Taking the former one as an example; ...
- 3,464
0
votes
2
answers
290
views
Flow of time in a block universe
On asking how there could be a flow of time in a block universe one user said
"In the block universe concept
there is no physical flow of time. The flow of time is a purely mental sensation that ...
user282467
1
vote
0
answers
52
views
What implications does special relativity have on the accelerating expansion of the universe? [duplicate]
Under special relativity we have the Lorentz factor:
$$
\gamma = \sqrt{\frac{1}{1-\frac{v^2}{c^2}}}
$$
Which essentially mathematically describes how the relative speeds between objects can never ...
- 261
3
votes
1
answer
96
views
Are questions about "when" an event outside the visible universe occurred meaningless?
It seems to me that the answer is yes, first of all because it is impossible in principle to use Einstein's definition of simultaneity in such cases since signals cannot pass from the event to us, and ...
- 290
3
votes
1
answer
289
views
The relationship between time, relativity and entropy
I came across a discussion about the nature of time and whether or not time is an illusion on a physics forum. I'm not so much interested in the philosophical issues regarding time, but the following, ...
- 586
1
vote
2
answers
195
views
Newton's First Law and things that are very old [closed]
Recently I've been revisiting physics text books, and books by Feynman, and others.
A curious thought has arisen, while I was reading about Mach's principle, and it seems to gnaw on my mind. I hope ...
- 390
2
votes
2
answers
2k
views
How can the universe be dodecahedron-shaped?
Physicsworld references "Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background" by J.-P. Luminet et al., published in Nature (...
- 1,145
1
vote
1
answer
182
views
Can the universe have different ages?
There is a similar question on here, but I figured this focuses on a more specific aspect. My apologies if it is seen as a duplicate. I am not a cosmologist. I do have a background in physics, ...
- 1,062
1
vote
0
answers
70
views
As space-time expands between two stars, what happens to the gravitational potential energy seemingly lost as U~1/r => ZERO.?
As the space-time between two stars grows (the accelerating expansion of the universe) the gravitational potential energy between two stars is reduced as 1/r -> ZERO (r is the distance between stars).
...
0
votes
1
answer
301
views
Could there be a time dilation of 2,000,000x between Earth and other parts of the universe?
Don't ask me why, but you may be able to guess why I would ask such a question. The question is, what kind of conditions would have to be present in a universe in order for billions of years pass in ...
- 145