a story about special relativity,who can explain it？

[TonyYuan]

A race between Newton and Einstein, who will win?
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?

scene2:https://photos.app.goo.gl/Zy12Qxz1WHXEehVg6
What is the relative speed of AB?

scene3:https://photos.app.goo.gl/cTUiMYNjXCdveHnQ6
What is the relative speed of AB?

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

 

[TonyYuan]

The bending of light and the speed of light are two different things. Your assertion is that light slows down, this is what you need to support, where are your answers and sources?

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.

 

[ralfcis]

What are your answers Tony. No one is going to respond until you show you've put in some effort. Now it's probably even too late for that.

 

[TonyYuan]

What are your answers Tony. No one is going to respond until you show you've put in some effort. Now it's probably even too late for that.

It may be that I directly copied the link without insert link, which caused you to be unable to open it. It should be OK now.
Google Photos is not very skilled, I hope that this problem will not happen again in the future.

 

[(Q)]

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.

I understand now that I can see that picture, thanks.

The bold outlines your critical error here, the beam does not act as a single unit, the beam is made up of photons and it is the photons that act independently of one another within the beam so that all photons will be moving at c before and after refraction. There is no slowing down of any photons other than when they transverse the medium of refraction.

 

[TonyYuan]

I understand now that I can see that picture, thanks.

The bold outlines your critical error here, the beam does not act as a single unit, the beam is made up of photons and it is the photons that act independently of one another within the beam so that all photons will be moving at c before and after refraction. There is no slowing down of any photons other than when they transverse the medium of refraction.

You can focus on the law of refraction: sinθ1/sinθ2 = v1/v2 = n2/n1.

I understand what you mean. This derivation is a rough light path model, but its conclusion is correct. I saw the derivation of this law of refraction and found it more interesting, simple and easy to understand. So directly copied over.

It is my pleasure to discuss these issues with you. Hope our efforts can reduce doubt for more people.

 

[(Q)]

You can focus on the law of refraction: sinθ1/sinθ2 = v1/v2 = n2/n1.

I understand what you mean. This derivation is a rough light path model, but its conclusion is correct. I saw the derivation of this law of refraction and found it more interesting, simple and easy to understand. So directly copied over.

It is my pleasure to discuss these issues with you. Hope our efforts can reduce doubt for more people.

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.

 

[TonyYuan]

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.

Yes, I fully agree with you that the speed of light will return to normal after leaving the medium.By the same token, the light will return to normal after leaving the gravitational field.

 

[Halc]

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.

This is actually a pretty good description of diffraction. What was the point? Yes, light travels at c only in a vacuum.

The bold outlines your critical error here, the beam does not act as a single unit, the beam is made up of photons and it is the photons that act independently of one another within the beam so that all photons will be moving at c before and after refraction. There is no slowing down of any photons other than when they transverse the medium of refraction.

I don't see any critical error. The beam can be considered a bunch of parallel waves, just like water in this case. Diffracted light behaves very much like waves and not particles.

 

[TonyYuan]

https://photos.app.goo.gl/LbJoTK2q5dX11TBe7
There are usually two reasons that can cause the object's motion path to bend. One is the velocity caused by the force in the vertical direction, and the other is the refraction caused by the unevenness of the medium or the unevenness of the field. Then the bending of the light is probably caused by the latter. The sun is surrounded by the gravitational field. The gravitational field is stronger as it goes inside. When light passes through the gravitational field of the sun, the light is bent similarly to refraction due to the unevenness of the gravitational field. The curvature of this path is different from the curvature caused by the direct action of gravity on an object. Therefore, it is not appropriate to calculate the bending angle of light using the classic flat throw theory.
https://photos.app.goo.gl/fcHk2UjEQufwdmw1A
This is because the theory of flat throw thinks that there is a co-directional acceleration process under the pull of gravity at the beginning, before the acceleration caused by gravity becomes negative, the light will be farther away from the sun and the influence of gravity will be smaller. The deflection angle will also be smaller. This is the reason why the angle of light deflection calculated by the classic flat throw theory is too small. Newtonian mechanics is not wrong, but this time it was not used correctly.
The rotation of the earth does not affect the strength of the gravity field. We should consider the revolution of the earth around the sun, and the gravitational field moves with the earth. The data we calculated are basically consistent with the experimental observation data given by Janus. But Janus thinks that the gravitational field of the earth is too weak to affect the bending of light, which is wrong.

Light deflected by just 0.0006 arc-seconds =1.667*10^-7 degree. This is the observation data given by Janus.
The earth's angular speed : 360/365*24*60*60 = 1.1415*10^- 5 degree/s.This is my calculated angular speed of the Earth's revolution around the sun.
If the time of light passing through the earth is 0.01 seconds, about 3000 km,the angle of rotation of the earth is 1.1415*10^- 7 degree. It can't be ignored!

 

[Write4U]

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?

 

[TonyYuan]

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?

This is a good question. This issue was also analyzed in my previous article. I think that on the one hand, the gravitational field will cause the refraction of light, and on the other hand, because light will be pulled by gravity, the speed of light will be superimposed on the gravitational field, that is, the speed of the earth's revolution around the sun. So the speed of light relative to the earth is constant.
Note: Light is held by the gravitational field and the speed of light will be superimposed on the gravitational field. This is different from the classic flat throw theory.

 

[(Q)]

I don't see any critical error. The beam can be considered a bunch of parallel waves, just like water in this case. Diffracted light behaves very much like waves and not particles.

Good point. But I don't think the beam can behave as one unit which is what Tony was suggesting.

 

[(Q)]

Yes, I fully agree with you that the speed of light will return to normal after leaving the medium.By the same token, the light will return to normal after leaving the gravitational field.

Gravity can cause the geodesics light travels to curve, but light will still be moving at c regardless of any gravitational field.

 

[TonyYuan]

Gravity can cause the geodesics light travels to curve, but light will still be moving at c regardless of any gravitational field.

The geodesic described in General Relativity and the gravitational field here are both models. You can use a geodesic or gravitational field independently. Do not mix the two together.

 

[(Q)]

The geodesic described in General Relativity and the gravitational field here are both models. You can use a geodesic or gravitational field independently. Do not mix the two together.

I can only assume by that response is that you don't know what a geodesic is and what happens to it in a gravitational field.

 

[TonyYuan]

I can only assume by that response is that you don't know what a geodesic is and what happens to it in a gravitational field.

The geodesic can be defined as the local shortest or longest path at two points in space. For example, the longitude of the earth is a geodesic. Maybe I'm not right, I'm not an expert on this.
General relativity tells us that space-time curvature caused by mass causes planets to move along geodesics. This model is perfect and I like it too. This process can also be best described using Newton's classical physics.

 

[(Q)]

The geodesic can be defined as the local shortest or longest path at two points in space. For example, the longitude of the earth is a geodesic. Maybe I'm not right, I'm not an expert on this.
General relativity tells us that space-time curvature caused by mass causes planets to move along geodesics. This model is perfect and I like it too. This process can also be best described using Newton's classical physics.

A geodesic is simply a path through space and is affected by large objects gravity when they are near it such that the path curve towards the object. If something is traveling along the path, it will move in a straight line if the geodesic isn't being affected by gravity, but once that something gets closer to a large object, the geodesic will curve and the something will curve along with it. The key here is that the something still thinks it's moving along a straight path even though the path is curved. The something does not experience any forces acting on it, which Newtons first law would usually require if the something were to change direction.

 

[TonyYuan]

A geodesic is simply a path through space and is affected by large objects gravity when they are near it such that the path curve towards the object. If something is traveling along the path, it will move in a straight line if the geodesic isn't being affected by gravity, but once that something gets closer to a large object, the geodesic will curve and the something will curve along with it. The key here is that the something still thinks it's moving along a straight path even though the path is curved. The something does not experience any forces acting on it, which Newtons first law would usually require if the something were to change direction.

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

 

[Write4U]

Perhaps this may not be pertinent, but Einstein's man in a box proves that what appears as a geodesic path may not be longer than a straight path.
In that case, what appears as a curved path actually travels in a straight line but it is the environment that is moving relative to the light.