All Questions
35
questions
0
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1
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137
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Confusion regarding Special Relativity and Relativity of Velocity? [duplicate]
Suppose that there are two points in an empty space A and B and observers at A and B having clocks:
If A were to be traveling near speed of light, when clock at A passes 1 hour, observer at A ...
-1
votes
1
answer
66
views
Sub-LightSpeed travel according to special relativity vs AP physics
For background, I'm a high school physics Student, and I was recently looking at special relativity out of personal interest, and I read a summarized statement "Time slows down as your approach ...
- 101
4
votes
1
answer
129
views
Wald's definition of energy of a massive particle
In R.Wald's book on "General Relativity" appears on p.61 (section 4.2) a rather peculiar definition of the energy of a massive particle:
$$ E = -p_a v^a \tag{4.2.8}$$
I guess the minus sign ...
- 9,778
-6
votes
2
answers
118
views
Does this break relativity? A humming bird is flying 30 km/h inside of a train [duplicate]
If I am in a high speed train, and I am sitting there, and I see a hummingbird flying $ 30 km/h $ relative to me towards the head of the train.
We all know, the scenario above is 100% possible by ...
- 332
0
votes
0
answers
53
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Question about theory of relativity [duplicate]
If you were running at a constant speed towards a light that is coming towards you and an other light was following you, from your perspective how is it possible that both lights go at the same speed....
- 11
1
vote
3
answers
265
views
Velocity addition in Special Relativity
A train is driving at 0.8c relative to the rails.
On the train, a car is driving with 0.8c relative to the train, in the same direction as the train.
How fast is the car driving relative to the rails?
...
- 41
0
votes
1
answer
51
views
When to consider the velocity of the other reference frame?
Let's say I have a spaceship going away from the Earth with speed $V=3/5c$ and it emits a light signal back to Earth when 1h in hit it spaceship time. This is the problem presented in this video and I'...
- 149
0
votes
4
answers
184
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Spaceships with relativistic instruments
I wonder if it is possible, for future spaceships, to have somekind of instruments on board, that will tell the pilot what his true speed through spacetime is and how much time dilation he is ...
- 107
1
vote
6
answers
897
views
Why doesn't the classical addition of velocities apply to light?
Recently, relativistic physics has sparked interest in me. I read in one of my textbooks that the classical addition of velocities does not apply to light but the explanation given in the book is ...
- 158
-7
votes
7
answers
392
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How is the relative speed of two (or more) objects determined (distributed) in the theoretical context of special relativity?
Let's assume that observers on two moving objects, A and B, each determine, using doppler shift detection devices, that they are approaching each other at the rate of of $.5\,c$.
It's only natural to ...
- 79
0
votes
1
answer
79
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Relativity and speed of light [duplicate]
This might be a stupid question but anyway here it goes.
Let's say that I move towards a friend of mine at 75% of $c$ relative to the earth. Then, he moves towards me at the same velocity.
When we ...
- 25
-3
votes
1
answer
93
views
What is the observed speed of two objects moving 200,000 km/s in opposite directions? [closed]
Point C is at rest at the origin.
Object A is moving east with speed 200,000 km/s, relative to Point C, and starts at coordinate (0, 200 km).
Object B is moving west with speed 200,000 km/s, relative ...
- 694
0
votes
1
answer
74
views
Who observes the light faster when the lamp is also traveling?
Say I have a lamp on a car $M$ in the middle of $A$ and $B$, who are both $c$ distance away from $C$. (so it takes light 1 second to travel to both $A$ or $B$ from $M$). Now the car starts traveling ...
- 101
1
vote
2
answers
118
views
Will the speed of object be the same for observers with different speeds if the speed of the object is closer to the speed of light? [closed]
If we assume an object X traveling at a speed $V$ that is a bit slower than the speed of light (let's say 1000 miles/sec.), what will be the difference in the observations of the speed of object made ...
- 21
-1
votes
2
answers
171
views
Time dilation on a rocket moving towards a photon
I have seen time dilation explained more or less in this way:
If you are in a rocket, racing a photon, and your rocket is almost at the speed of light, technically you would see the photon moving ...
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