All Questions
188
questions
-3
votes
3
answers
213
views
Does proper time have two different values or meanings? [closed]
I'm trying to intuitively understand proper time which is defined as the time that is always measured in a moving observer’s or particle's rest frame and is given by the equation
$\Delta\tau = \sqrt{1 ...
- 335
2
votes
5
answers
355
views
Special Relativity and Hypersurface of Simultaneity?
In Special Relativity when I move backwards and forwards my hypersurface of simultaneity moves too.
Does time really oscillate backwards and forwards as I move around? Or is it just the application of ...
- 65
2
votes
2
answers
97
views
Is it possible for a Ricci-flat manifold to have a negative energy measured by distant observers?
Supposing that there is a stationary sphere made of regular matters, the external spacetime geometry can be described by the Schwarzschild metric, which describes a spacetime with vanishing Ricci ...
- 1,455
-1
votes
3
answers
97
views
Is there a "micro" explanation for why time slows down in relativity?
I know the explanation involving a clock based on reflected light. But why would every physical/chemical process be slower? Not that the following is a very good idea, but could it be something like, ...
- 2,238
0
votes
0
answers
27
views
Is it correct to say that acceleration slows the frequency of an oscillator?
My question is based on differential aging or differential timekeeping due to, 1) increased speed, and 2) proximity to center of gravitational field. As far as I know, both involve acceleration, and ...
- 1
0
votes
2
answers
159
views
Observers in General Relativity: do transformations happen between two different observers or between two local coordinates both of the same observer?
In my understanding of general relativity, I am a little confused. Could someone please clarify this:
Given the definition of a manifold with its collection of subsets(patches) and mapping functions, ...
- 306
0
votes
1
answer
209
views
What is the definition of an asymptotic observer?
I can't find the definition of it in Wikipedia or in books on my bookshelf.
- 898
1
vote
5
answers
497
views
Is relativity of simultaneity an "observer issue"?
There are some threads about this, but some answers seem to disagree.
First, this is what Einstein said on this matter:
The light rays emitted by the flashes of lightning A and B would reach him ...
- 11
-2
votes
2
answers
148
views
How meaningful is the notion of 'now' here on Earth? [closed]
So special relativity and the lack of a now moment is causing me a bit of grief.
My friends and families notion of "now" doesn't ever line up with mine; but how much of a difference does ...
- 65
-2
votes
1
answer
103
views
Are the distance of things different as we change the reference frames? [duplicate]
x' = γ(x - vt)
We know the time that has passed from each references are different. And it influences the speed of things in each station and bus, but I think that ...
- 23
0
votes
0
answers
39
views
Is length contraction actually get things smaller or is it just how one reference frame look at things? [duplicate]
I want to check something..
when we nearly reach the speed of light, we'd look the length of things differently. Although we know that the speed of light is the same for all reference frames. Is it ...
- 23
0
votes
1
answer
120
views
Aging when travelling at relativistic speeds
I have a twin. If I acquired a craft that travels at 10% of light speed and wanted to go to Proxima Centauri, it seems now like it would take me 42 years to get there. Would I be 42 years older when I ...
- 740
1
vote
1
answer
81
views
Does the ladder really fit inside the barn?
Does the ladder really fit inside the barn?
If we could take a photo, would we see the ladder inside the barn?
- 55
1
vote
0
answers
170
views
Rindler Observers
In the process of transition from STR to GR, I'm trying to understand what Rindler observers actually are. Here is how one of the questions from our assignment defines them:
If the distance between B ...
- 67
-4
votes
3
answers
203
views
Twins Paradox: Back on Earth, same moment? (and always) [closed]
Supposing twin A, having been on a well-known circular near-light-speed journey, returns to Earth a younger man than twin B.
Let's say A took off at 3pm and upon return has aged 2 hours while B has ...
- 383