All Questions
14
questions
4
votes
5
answers
647
views
What can we accept in thought experiments in relativity?
Although title is more broad, and you are welcome to give examples, I will ask about why we accept certain things as acceptable in Einstein's thought experiments using a specific experiment:
Consider ...
- 351
2
votes
1
answer
76
views
What does it mean that an observer can provide a quantitative temporal order only to the events on his worldline?
I'm currently reading the introduction to Naber's The Geometry of Minkowski Spacetime, and in this post I'm writing down a few silly questions that keep popping into my head. I have near-zero formal ...
1
vote
2
answers
132
views
Do events very far away happen in a different timeline?
I am not sure how to ask this question in a concise manner so I am sure somebody out there explained it but I cannot seem to find it.
So I recently watched some videos explaining that $c$ not only ...
- 119
1
vote
1
answer
89
views
What does hypersurface of simultaneity exactly mean?
HSS - "Hyper Surface of Simultaneity"
Listening to different sources online I understood that HSS for a observer represents the points that are at same moment of time.
Consider a 1d world. ...
-1
votes
1
answer
73
views
The train-and-platform VS Causality and Simultaneity
for long time I was ruminating on the train and platform experiment and “what if” extension of this experiment…
So, what if the light striking on either end triggers system (one on each end) with ...
- 19
1
vote
1
answer
849
views
Why Going Faster-Than-Light (FTL) Leads to Time Paradoxes? [duplicate]
In this video: https://www.youtube.com/watch?v=an0M-wcHw5A&lc=UgxqC71gefTRIuVubGt4AaABAg.9jI6ltMIeu59jx2P8cpn_z
In the video the following events happen:
A supernova goes off.
Earth sees the ...
- 2,706
50
votes
5
answers
12k
views
Could I, within my lifetime, reach any star I wanted if I went fast enough?
Disclamer: I'm not talking about FTL travel here. I'm also not talking about any weird space warping mechanics like wormholes and such.
I've always thought that if a star was 4 light years away, then ...
- 621
4
votes
3
answers
183
views
Can information travel faster than speed of light in this situation?
I know the answer is no but I have a thought experiment that seem to be violating that. Imagine two persons living on two different planets namely A and C which are 10 light years apart. There is a ...
- 49
3
votes
0
answers
98
views
Axiomatization of SR: can we replace light rays with timelike world-lines?
If I eliminate a lot of details and just sketch the general ideas, then a common way of presenting SR is this:
Axiom 1: Clocks exist.
Axiom 2: Light rays exist.
This is the approach followed in, e.g....
user4552
36
votes
3
answers
9k
views
Is there a frame of reference in which I was born before I was conceived?
I'm struggling to understand the relativity of simultaneity and position.
If my conception and birth are separated by time but not space, a frame of reference in which my birth and conception are ...
- 740
-1
votes
1
answer
2k
views
Why specifically does FTL violate causality? [duplicate]
Take this non-FTL scenario, involving a phone call and the postal service.
I send a postcard to my friend in Paris, asking whether they would like to visit me. Since it will take some time to arrive,...
- 127
2
votes
1
answer
627
views
Light cone and order of events?
If one event lies outside the light cone of another, can the events to some observers appear in a different order in one reference frame compared to the other, and is this the only time when this is ...
user43487
2
votes
2
answers
94
views
Is it ok to have two events $A$ and $B$ so that for one person $A$ occurs before $B$ but for another $B$ preceds $A$
Imagine two laser beams A and B are released at the same moment to bounce between two mirrors, A was moving and B was at rest, doing the calculations I found that for a person at rest B would reach ...
9
votes
5
answers
8k
views
Why is causality preserved in special relativity?
PART 1:
I was reading the article Relativity of simultaneity Wikipedia. I couldn't understand this line:
"if the two events are causally connected ("event A causes event B"), the causal order is ...
- 1,601