a story about special relativity,who can explain it？
- Thread starter TonyYuan
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And, how do you know the speed of light is not constant and that SR is not tenable?
General relativity is a physical theoretical model, just like gravitation, all of which are physical models.
If that was the case the we wouldn't have SR. Obviously it is not the case, and the speed of light is constant in a vacuum, and follows geodesics in spacetime.
speed +
Why does the speed of light change direction? The X-ray is bent, which means that the y-direction increases the speed. Where does the y-direction speed come from? It's because of gravity. So the speed in the X direction remains the same? Or has it changed? Can you tell me?
The speed of light measured anywhere on the earth is constant. Whether it's a vacuum or not.
And any scientific theory is as good as it gets, and our best solution at that time.
Again, Light/photons follow geodesics in spacetime
This is also a model. It can be explained correctly with classical physics.
Halc
Registered Senior Member
No it isn't. If I walk along the aisle of an airplane, speed of sound relative to me is not constant. With light, it stays constant. That's huge evidence that there is a medium for sound but not for light.
This is a metaphor. No one has ever measured the speed of light in the sun or a black hole.
Let's focus on my question, the fifth scene.
Fifth scene:
Earth.....................................A---->u=0.2C............................B---->w=0.8C
What is the velocity v of B relative to the earth?
w = (u-v)/(1-uv/c^2) = (0.2C - v)/(1-0.2C*v/C^2) = 0.8C
0.2-v=(1-0.2v)*0.8
0.84v = -0.6
v = -0.714C, the velocity v of B relative to the earth is -0.714C, velocity direction is opposite to A.
But A sees B moving away at 0.8C, what happened?
You can see different u and different w, v can get different directions, which is very interesting. For example:
if v=0.2C,w=0.1C
w = (u-v)/(1-uv/c^2) = (0.2C - v)/(1-0.2C*v/C^2) = 0.1C
0.2-v=(1-0.2v)*0.1
0.98v = 0.1
v = 0.102C,v direction is same to A.
Halc, i want hear your voice.
Earth.....................................A---->u=0.2C............................B---->w=0.8C
What is the velocity v of B relative to the earth?
w = (u-v)/(1-uv/c^2) = (0.2C - v)/(1-0.2C*v/C^2) = 0.8C
0.2-v=(1-0.2v)*0.8
0.84v = -0.6
v = -0.714C, the velocity v of B relative to the earth is -0.714C, velocity direction is opposite to A.
But A sees B moving away at 0.8C, what happened?
You can see different u and different w, v can get different directions, which is very interesting. For example:
if v=0.2C,w=0.1C
w = (u-v)/(1-uv/c^2) = (0.2C - v)/(1-0.2C*v/C^2) = 0.1C
0.2-v=(1-0.2v)*0.1
0.98v = 0.1
v = 0.102C,v direction is same to A.
Halc, i want hear your voice.
Last edited:
So? That's what science/physics does...model what we see. And that model stands as the accepted "scientific theory" until something better comes along. You have not done that and if you had, you would be in line for the Physics Nobel in November.
I gree with you.
No one needs to. It matches and aligns with our successful theory/model perfectly.
So what are you saying? Sorry, I did come into this late, but you seem to be saying that "c" is not constant, which would invalidate SR, which is not the case.
My understanding is that gravity either increases or decreases the energy/frequency depending on which way it's traveling near an object, not the speed.
exchemist
Valued Senior Member
How do you account for the observed flux of muons due to cosmic rays, without using SR?
http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/muon.html
I really haven't studied this and can't express my opinion.
Fifth scene:
Earth.....................................A---->u=0.2C............................B---->w=0.8C
What is the velocity v of B relative to the earth?
w = (u-v)/(1-uv/c^2) = (0.2C - v)/(1-0.2C*v/C^2) = 0.8C
0.2-v=(1-0.2v)*0.8
0.84v = -0.6
v = -0.714C, the velocity v of B relative to the earth is -0.714C, velocity direction is opposite to A.
But A sees B moving away at 0.8C, what happened?
You can see different u and different w, v can get different directions, which is very interesting. For example:
if v=0.2C,w=0.1C
w = (u-v)/(1-uv/c^2) = (0.2C - v)/(1-0.2C*v/C^2) = 0.1C
0.2-v=(1-0.2v)*0.1
0.98v = 0.1
v = 0.102C,v direction is same to A.
exchemist
Valued Senior Member
But if you assert that SR is not reliable, you need to be able to explain this without using it, you see. Accounting for this - and other experiments involving the apparent change in lifetime of sub-atomic particles - is one of SR's notable successes.
I've heard about this experiment. 10 years ago, I had different opinions. But the topic has no energy today. A little sleepy.
I studied the formula given by Janus, and I did the analysis. You can see it.