a story about special relativity,who can explain it？

[exchemist]

Sorry, but your conclusion that the light slowed is not correct. The only time the photons slowed was while it went through the refractive medium. Before and after that, the photons traveled at c.

And even then it is only the phase velocity that is slowed. The signal velocity, so I understand, still travels at c when light passes through an optically dense medium. One has to be awfully careful with refraction, I have found, occasionally to my cost.

 

[TonyYuan]

A race between Newton and Einstein, who will win? Who can give the answer?
https://photos.app.goo.gl/o2WkLK5M3uji7aMc7


There are several scenarios here. The distances between A and B are the same.
If you are interested, you can try to answer the following questions based on these scenarios.
scene1: https://photos.app.goo.gl/GTvVoKDWDBqPPe4c9
What is the relative speed of AB?
Janus gave the answer: w=(0.2c+0.4c)/(1+0.2c*0.4c/c^2) = 0.555c.

scene2:https://photos.app.goo.gl/Zy12Qxz1WHXEehVg6
What is the relative speed of AB?
Janus gave the answer: w=(-0.2c+0.4c)/(1-0.2c*0.4c) = 0.217c.

scene3:https://photos.app.goo.gl/cTUiMYNjXCdveHnQ6
What is the relative speed of AB?
Janus gave the answer: r=sqrt[1-(0.4c)^2/c^2] ; w=sqrt[(r*0.2c)^2+(0.4c)^2] = 0.44c.

scene4:https://photos.app.goo.gl/UuUJ6ABoY2M6W5jv6
What are the speeds of A and B relative to C? Who can give the answer?
A and B who will reach Earth first?


scene5:https://photos.app.goo.gl/UowoF19W5MfZ6GAJ6
What are the speeds of A and B relative to C? Who can give the answer?
A and B who will reach Earth first?

scene1,2,3 Janus has given the answer, the race game is still waiting for Janus' answer, scene4,5 who can give answer?

 

[exchemist]

scene1,2,3 Janus has given the answer, the race game is still waiting for Janus' answer, scene4,5 who can give answer?

The more you treat this facetiously, as a "game", the less likely you are to get replies.

But perhaps that is what you want, so that you can spuriously claim "victory", when everyone ignores you.

 

[TonyYuan]

The more you treat this facetiously, as a "game", the less likely you are to get replies.
But perhaps that is what you want, so that you can spuriously claim "victory", when everyone ignores you.

For each friend's response, I will take it seriously and will answer your questions one by one. Why do you think this is a game? We can discuss these scientific issues very seriously, and we can also discuss these issues together happily. If you do n’t know the answer, just say you do n’t know. This is not a shame.
Using my current knowledge to analyze, scenarios 4, 5 can only reach conflicting conclusions. That's why I organized the 5 scenes into a topic to ask questions. I hope that if you know, you can give an answer bravely. If you don't know, then wait quietly for an authority like Jadus to answer.
If I am wrong, you can become my teacher and tell me what is right. If I am right, my article can also bring meaningful wisdom to more people.
exchemist, my friend , my chemistry course has always been excellent, and I have won the National Olympic Chemistry Competition award. I believe that I will also have some good ideas on the topic of chemistry, which we can discuss together.

 

[exchemist]

For each friend's response, I will take it seriously and will answer your questions one by one. Why do you think this is a game? We can discuss these scientific issues very seriously, and we can also discuss these issues together happily. If you do n’t know the answer, just say you do n’t know. This is not a shame.
Using my current knowledge to analyze, scenarios 4, 5 can only reach conflicting conclusions. That's why I organized the 5 scenes into a topic to ask questions. I hope that if you know, you can give an answer bravely. If you don't know, then wait quietly for an authority like Jadus to answer.
If I am wrong, you can become my teacher and tell me what is right. If I am right, my article can also bring meaningful wisdom to more people.
exchemist, my friend , my chemistry course has always been excellent, and I have won the National Olympic Chemistry Competition award. I believe that I will also have some good ideas on the topic of chemistry, which we can discuss together.

I don't think it's a game. What I'm saying is you are creating that impression.

You, post 62: "Is this a math game?"
You, post 64: "As a teacher, I want to find out whether it is a mathematical game."
You, post 123: " .

Digital game.

"
You, post 124:" ......

Digital game.

"
You, post 134:"A race between Newton and Einstein, who will win?"
You, post 138: " I will be a good match for Janus. Also, for me, he is the best opponent."
You, post 144: " So please use special relativity to explain this running race and tell us whether Newton won or Einstein won."
You, post 182: " scene1,2,3 Janus has given the answer, the race game is still waiting for Janus' answer, scene4,5 who can give answer?"

And now you start up this chemistry nonsense, beginning by referring to a competition that does not exist.

My crank detector went off long ago, but now my troll detector has gone off as well.

 

[TonyYuan]

I don't think it's a game. What I'm saying is you are creating that impression.

You, post 62: "Is this a math game?" Special theory of relativity is a mathematical game and I always wanted to get an answer.
You, post 64: "As a teacher, I want to find out whether it is a mathematical game." Same as above
You, post 123: " .

Digital game.

" Same as above
You, post 124:" ......

Digital game.

"Same as above
You, post 134:"A race between Newton and Einstein, who will win?" Please see this picture, you will know what this race game is.
https://photos.app.goo.gl/rYqi35mm7YToACys5
You, post 138: " I will be a good match for Janus. Also, for me, he is the best opponent."We are very good opponents. Like James and Curry
You, post 144: " So please use special relativity to explain this running race and tell us whether Newton won or Einstein won."Same as above
You, post 182: " scene1,2,3 Janus has given the answer, the race game is still waiting for Janus' answer, scene4,5 who can give answer?"Same as above

And now you start up this chemistry nonsense, beginning by referring to a competition that does not exist.

My crank detector went off long ago, but now my troll detector has gone off as well.

My friend, if you could read my text carefully, you would not think so. The purpose of the Olympic Games is to become stronger, faster and higher through competition. If you want, then let us continue. It doesn't matter if you don't want to. We are still friends.

We have an old saying here: Don't know each other without hitting.

I like the atmosphere of scientific research here, and hope to work with you to solve various questions and improve various theories. Maybe we have various arguments, but we all seek the truth for a common purpose.

 

[exchemist]

I've read that a photon may spend a thousand years inside the sun trying to escape, but once it reaches the surface it takes 8 minutes to reach the earth.

Is that an example of refraction or just plain obstruction?

Neither. Just an example of attempted thread diversion.

 

[(Q)]

Under the influence of gravity and inertia, physics moves along the geodesic.

Physics doesn't move anywhere, it's not an object, it's a category of science. You really are very confused.

If the force disappears, the object will move at a constant speed in a straight line. When there is mass, there will be bending in space, and when there is no mass, there will be no bending. Mass causes the existence of a gravitational field. Newton's first law does not encounter difficulties in this matter.

We are not talking about bending of light, you are supposed to support your claim that light slows down, you have not done that, all you have done is danced around. Clearly, you need to come clean and admit you're just blowing hot air and have no idea what you're claiming.

 

[(Q)]

If you do n’t know the answer, just say you do n’t know. This is not a shame.

Then, why are you not admitting to not knowing what you're talking about?

 

[(Q)]

You, post 64: "As a teacher, I want to find out whether it is a mathematical game."

And now you start up this chemistry nonsense, beginning by referring to a competition that does not exist.

My crank detector went off long ago, but now my troll detector has gone off as well.

I must have missed that, he says he's a teacher?

 

[exchemist]

I must have missed that, he says he's a teacher?

Well, some teachers I have encountered are cranks, in one way or another. I was taught A level physics (50 years ago) by a man who professed not to believe in molecules. He was an excellent teacher - of classical c.19th physics. But he was not someone who got his algebra in a muddle.

 

[Write4U]

Physics doesn't move anywhere, it's not an object, it's a category of science. You really are very confused.

With respect, (Q), is that not a little bit of cherry-picking?

Definition of physics
1: a science that deals with matter and energy and their interactions
2a: the physical processes and phenomena of a particular system
b: the physical properties and composition of something

https://www.merriam-webster.com/dictionary/physics

Then to make a definitive declaration based on such a minor distinction seems almost hostile ?

 

[Write4U]

Question; Does spacetime get denser in a gravity field? If so, is it possible that light can indeed slow down near a very massive object?
Apparently light can in fact slow down in a dense medium. How about dense spacetime?

Just a question...

 

[(Q)]

With respect, (Q), is that not a little bit of cherry-picking?
https://www.merriam-webster.com/dictionary/physics

Then to make a definitive declaration based on such a minor distinction seems almost hostile ?

Perhaps, you can make heads or tails of what Tony said? I assumed he thought "physics" was the object itself. Did I misread that?

"Under the influence of gravity and inertia, physics moves along the geodesic."

 

[Write4U]

"Under the influence of gravity and inertia, physics moves along the geodesic."

or losely translated;

"Under the influence of gravity and inertia, 2a: the physical processes and phenomena of a particular system ("....moves along the geodesic.")

"Under the influence of gravity and inertia, b: the physical properties and composition of something ("....moves along the geodesic.")

Even as layman I don't find that difficult to understand....

 

[(Q)]

Question; Does spacetime get denser in a gravity field? If so, is it possible that light can indeed slow down near a very massive object?
Apparently light can in fact slow down in a dense medium. How about dense spacetime?

Just a question...

That may be answered with a quantum theory of gravity, of which there currently isn't one. That is, with the field equations, the stress energy tensor predicts how particles following their geodesics will behave in a gravity field, but as yet, there is no understanding how this is caused. So far, the findings don't show light slowing down in a gravity field, it either gains energy or loses it, ie; blueshift or redshift.

 

[TonyYuan]

Physics doesn't move anywhere, it's not an object, it's a category of science. You really are very confused.
correction:Under the influence of gravity and inertia, the object moves along the geodesic.
We are not talking about bending of light, you are supposed to support your claim that light slows down, you have not done that, all you have done is danced around. Clearly, you need to come clean and admit you're just blowing hot air and have no idea what you're claiming.

https://photos.app.goo.gl/37wqMvBY1c9RvNQS8
Let the speed of light in media 1 and 2 be v1 and v2, and take the width of the beam as d.
If the left end of the beam is in contact with the interface at t = 0, then the right end of the beam will only touch the interface when t = dsinθ1 / v1, at this point, the left end of the beam has advanced v2 * dsinθ1 / v1.
sinθ2=(v2*dsinθ1 / v1)/d.
n1=c/v1; n2=c/v2, then we can get the well-known law of refraction: sinθ1/sinθ2 = v1/v2 = n2/n1.
The refraction of light must be due to a change in speed, either faster or slower. From the direction of light bending through the sun, the speed is slower.

Hope my explanation can help you understand my point

 

[TonyYuan]

Question; Does spacetime get denser in a gravity field? If so, is it possible that light can indeed slow down near a very massive object?
Apparently light can in fact slow down in a dense medium. How about dense spacetime?

Just a question...

From the perspective of light bending, the light is refracted under the gravitational field. The law of refraction has clearly stated that the refraction of light is related to changes in the speed of light.

 

[TonyYuan]

That may be answered with a quantum theory of gravity, of which there currently isn't one. That is, with the field equations, the stress energy tensor predicts how particles following their geodesics will behave in a gravity field, but as yet, there is no understanding how this is caused. So far, the findings don't show light slowing down in a gravity field, it either gains energy or loses it, ie; blueshift or redshift.

The Doppler effect only affects the frequency of light, which affects the energy density of photons, but the total photon energy does not change and does not affect the speed of light.

The Doppler effect can also be used to illustrate that light is being pulled by a gravitational field. When the star is stationary relative to the earth, we cannot observe the Doppler effect, but when the star is far away, the wavelength of light is stretched to show a red shift, and when the star is near, the wavelength of light is compressed to show Blue shift.
If light is not being pulled by the star's gravity, the frequency of the photons will not change.

 

[Write4U]

From the perspective of light bending, the light is refracted under the gravitational field. The law of refraction has clearly stated that the refraction of light is related to changes in the speed of light.

That seems to be supportedby this;

Does the speed of light change in air or water?
Yes. Light is slowed down in transparent media such as air, water and glass. The ratio by which it is slowed is called the refractive index of the medium and is usually greater than one.* This was discovered by Jean Foucault in 1850.

When people talk about "the speed of light" in a general context, they usually mean the speed of light in a vacuum. They also usually mean the speed as measured in an inertial frame. This vacuum-inertial speed is denoted c.

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html

But the question remains, does spacetime (the vacuum) itself become denser in the gravity field of a massive object?