All Questions
19
questions
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Can we consider that the photons that were not and will never be detected live in a zero-dimensional space? [closed]
According to Einstein’s theory of relativity, any particle traveling at the speed of light experiences no passage of time. It follows that if a photon travels through space then within any two points ...
- 115
1
vote
0
answers
75
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How long until light reaches me if I travel away from a point? [closed]
Let's assume that:
I'm 1 light year away from some point in space
I'm travelling away from that point at 0.5c (or whatever fraction of the speed of light it takes for relativity to play a big role)
A ...
- 111
1
vote
4
answers
781
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Frame of reference of a photon [duplicate]
I'm curious about the fact that it is impossible to consider a frame of reference where a photon is the reference itself (meaning a frame of reference where this photon can't move).
I looked for ...
user343933
7
votes
3
answers
2k
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Is photon path pre-defined at the time of emission? [duplicate]
I am probably missing an important aspect here, but here are two thought experiments I came up with that make me quite a bit confused. Can some one explain to me, if I am missing any important aspects ...
- 79
0
votes
1
answer
110
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Why the proper time of photon is zero? [duplicate]
I'm currently taking classes on General Relativity, and whilst working on Geodesis equation:
Find out that for mass particle q is equivalent to proper time but in case of photon the proper time of ...
- 33
0
votes
2
answers
622
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Do photons travel instantaneously? [duplicate]
Special Relativity tells us - the faster things travel their time is slower relative to a stationary observer. Do massless particles, like photons travelling at the speed of light, “experience” zero ...
- 49
2
votes
1
answer
1k
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Energy of a photon in different reference frames
I'm currently reading Gravitation by MTW, and in it they postulate that the energy of a photon in a moving observers reference frame is,
$$E = -\mathbf{p} \cdot \mathbf{u}$$
Where $\mathbf{p}$ is the ...
- 221
1
vote
1
answer
72
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What is speedlight travel "really" like (for a photon)? [duplicate]
To begin with, I'm clearly not a physicist but I'm certainly interested by several physics questioning.
So, my question here is, according to Einstein's relativity, I understood that travelling at the ...
1
vote
2
answers
504
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Time and distance in a photon's frame of reference
Disclaimer, not a physicist.
When I look at the sky I can see the star Rho Cassiopeiae. In my frame of reference, the photon hitting my retina has traveled for 4000 years and 3.78x10^16 km. In the ...
- 111
0
votes
1
answer
80
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Would an observer going faster than the speed of light in a vacuum be able to observe photons that they emit? [closed]
If I could exceed the speed of light in a vacuum, would I be able to see photons that I previously emitted?
Would this be theoretically possible?
3
votes
3
answers
2k
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Proper time for a light particle
For a mass point in a local intertial system on which no forces act, we have that
$$ \frac{\partial^2\xi}{d\tau^2}=0$$
where $\tau$, the proper time, is defined through $ds = c d\tau$
and the $\xi$ ...
- 91
10
votes
2
answers
992
views
What is the size of the world for a photon?
At relativistic speeds the distances contracts. What is the contraction ratio in the dimensions along the axis of travel between a static observer and a photon passing by?
- 1,586
4
votes
2
answers
289
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Is the existence of a photon relative? [duplicate]
If an observer passes an electron, in such a way that the observer is accelerating, the observer would see photons because accelerating charges induce electromagnetic waves.
But from point of view of ...
- 3,348
1
vote
2
answers
156
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How can photon have wave properties if they travel at the speed of light? [duplicate]
I am not a physicist so please excuse me if this is a dumb question.
As far as I understand Relativity, as observer (in this case a photon) travels at the speed of light, time stops. So how can the ...
- 753
1
vote
1
answer
266
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Pair production in different reference frames
I understand that energy of photons is defined by their wavelength/frequency. This frequency (and so energy) will be different for different observers: observer moving towards the photon will see ...
- 323