Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: myuncle on 12/04/2021 18:23:01

Title: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: myuncle on 12/04/2021 18:23:01
Letís say there are two tv playing the same movie, one screen is in front of you (direction of spaceship travel), the other screen is behind you (opposite the travel direction). I suppose the movie played by the screen in front of you will appear and reach your eyes as if the movie was played at higher speed than normal. The movie played by the screen behind you will appear and reach your eyes as if the movie was played at slower speed than normal.
The sounds will reach your ears in the same way from both tv speakers, and they will both sound normal, like on Earth. But they will be both out of sync with the images: the sounds coming from the screen in front of you will reach your ears after the images, and the sounds coming from the screen behind will reach your ears before the images.
Playing tennis inside the spaceship. Seeing and feeling will be out of sync. Actually letís make it easier than tennis. There are two guys throwing a tennis ball to hit your head. Like for the tv case, one guy is in front of you (direction of spaceship travel), the other guy is behind you (opposite the travel direction). When the guy in front of you throws the ball, you will feel as if the ball is hitting your head after it reaches you. When the guy behind you throws the ball, you will feel as if the ball hits your head before the ball reaches you.
What do you think? 8)
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Halc on 12/04/2021 18:49:33
You've not said if the ship is accelerating or not.

If it is not accelerating, then it is stationary in its own frame and the two movies will be indistinguishable in every way, assuming you're the same distance from each of them and they were started simultaneously relative to the frame of the ship. Nothing is out of sync. Playing tennis will not work in free-fall.

If the ship is accelerating, then you can apply the equivalence principle and say that the experience is the same as watching two screens in a building, one a few floors above you, and one a few floors below you.  If they're started simultaneously in the frame of the building, the one above you will run faster and slowly get out of sync with the one below you. Same thing on the ship. Playing tennis only works if you're horizontal relative to each other, not one above the other, so the tennis thing would be like trying to play tennis in an elevator shaft, which doesn't sound much like tennis.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Bored chemist on 12/04/2021 19:10:52
The great thing about the word "spaceship" is that it isn't well defined.

Imagine that I enlist the help of some aliens to build a ship.
They have immense resources and technology and can do things that we consider "miracles"- but they are still bound by the laws of physics.

I ask them to build me a ship capable of carrying me and my friends (reasonably) safely through the cosmos.

What I didn't take account of was their sense of humour.

They just copy the solar system and put me + my "crew" on the "New Earth".
Fortunately, some of my friends are farmers so... Here I am, on my ship which looks pretty much like Earth.


Now imagine that I choose to measure the speed of my ship with respect to a cosmic ray that's going past at nearly the speed of light.
Well, that's as good a reference as any.
And it means that I'm traveling at nearly the speed of light.

Now, can you explain why watching a couple of films, or playing tennis would be any different?
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: myuncle on 12/04/2021 19:12:31
You've not said if the ship is accelerating or not.

If it is not accelerating, then it is stationary in its own frame and the two movies will be indistinguishable in every way, assuming you're the same distance from each of them and they were started simultaneously relative to the frame of the ship. Nothing is out of sync. Playing tennis will not work in free-fall.

If the ship is accelerating, then you can apply the equivalence principle and say that the experience is the same as watching two screens in a building, one a few floors above you, and one a few floors below you.  If they're started simultaneously in the frame of the building, the one above you will run faster and slowly get out of sync with the one below you. Same thing on the ship. Playing tennis only works if you're horizontal relative to each other, not one above the other, so the tennis thing would be like trying to play tennis in an elevator shaft, which doesn't sound much like tennis.

I am talking about free fall, no acceleration, I thought it was obvious, but thank you for chiming in. And no tennis, just a ball thown to hit you.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Bored chemist on 12/04/2021 19:14:49
Did you see my point about measuring my speed WRT a passing cosmic ray?

We are on a ship travelling at nearly the speed of light; it's just that you didn't notice.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: myuncle on 12/04/2021 19:33:19
Did you see my point about measuring my speed WRT a passing cosmic ray?

We are on a ship travelling at nearly the speed of light; it's just that you didn't notice.

you mean the Earth is travelling near the speed of light?
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Bored chemist on 12/04/2021 19:44:04
Did you see my point about measuring my speed WRT a passing cosmic ray?

We are on a ship travelling at nearly the speed of light; it's just that you didn't notice.

you mean the Earth is travelling near the speed of light?
Yes.
And it is also stationary.
That's what it means when people talk about "relativity".
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: myuncle on 12/04/2021 20:21:48
Did you see my point about measuring my speed WRT a passing cosmic ray?

We are on a ship travelling at nearly the speed of light; it's just that you didn't notice.

you mean the Earth is travelling near the speed of light?
Yes.
And it is also stationary.
That's what it means when people talk about "relativity".


Sorry, I don't get you. Doing a quick google search, the speed of the Solar System around Milky Way is approximately 220 km/s (490,000 mph) or 0.073% of the speed of light. And even if you add the Milky Way motion towards Andromeda, the speed is about 368 km/s, which is still nothing compared to light speed.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Origin on 12/04/2021 20:31:12
Sorry, I don't get you. Doing a quick google search, the speed of the Solar System around Milky Way is approximately 220 km/s (490,000 mph) or 0.073% of the speed of light. And even if you add the Milky Way motion towards Andromeda, the speed is about 368 km/s, which is still nothing compared to light speed.
He is saying from the frame of cosmic particle we are traveling at nearly the speed of light.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: myuncle on 12/04/2021 21:31:48
Sorry, I don't get you. Doing a quick google search, the speed of the Solar System around Milky Way is approximately 220 km/s (490,000 mph) or 0.073% of the speed of light. And even if you add the Milky Way motion towards Andromeda, the speed is about 368 km/s, which is still nothing compared to light speed.
He is saying from the frame of cosmic particle we are traveling at nearly the speed of light.

ah ok, who cares about a cosmic particle point of view, I am talking about a freaking human inside a Sci-Fi ship at 98% the speed of light ;D, just for fun. What is he/she going to experience considering that images and sounds have to make their journey before reaching your eyes/ears (and skull in the case of the ball).
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Halc on 12/04/2021 22:01:20
ah ok, who cares about a cosmic particle point of view, I am talking about a freaking human inside a Sci-Fi ship at 98% the speed of light
From the point of the freaking human inside the ship, the ship is stationary by definition. Per the 400 year old Galilean principle of relativity, everything works normally inside the box (ship), so he notices nothing.
You seem to be under the delusion that speed is absolute and it is meaningful for a ship to be going at .98c without giving a reference. The cosmic particle can be the reference.  Anything can. There is no speed I can go where there isn't a planet somewhere that is very very close to stationary relative to me. So Earth is very much moving at .98c relative to some planet 13 billion light years away, and yet we don't see the difference between the various televisions in the pub.

Quote
What is he/she going to experience considering that images and sounds have to make their journey before reaching your eyes/ears (and skull in the case of the ball).
Relativity theory says that no abnormal experience will be had. The one TV is 10 meters that way and the other is 10 meters the other way. Light moves at c relative to the ship or any other inertial frame, so the two are nicely in sync since it takes light equal time to reach you from each direction.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Bored chemist on 12/04/2021 22:04:17
ah ok, who cares about a cosmic particle point of view,
Physics cares.


Once you realise that, from that point of view, we are already going at the speed of light then you know what happens if we are going at the speed of light. Nothing.

No calculations or anything are needed.
You know, with absolute certainty that you can not observe any difference.

Just think of the effort you could save.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: myuncle on 12/04/2021 23:32:40
ah ok, who cares about a cosmic particle point of view, I am talking about a freaking human inside a Sci-Fi ship at 98% the speed of light
From the point of the freaking human inside the ship, the ship is stationary by definition. Per the 400 year old Galilean principle of relativity, everything works normally inside the box (ship), so he notices nothing.
You seem to be under the delusion that speed is absolute and it is meaningful for a ship to be going at .98c without giving a reference. The cosmic particle can be the reference.  Anything can. There is no speed I can go where there isn't a planet somewhere that is very very close to stationary relative to me. So Earth is very much moving at .98c relative to some planet 13 billion light years away, and yet we don't see the difference between the various televisions in the pub.

Quote
What is he/she going to experience considering that images and sounds have to make their journey before reaching your eyes/ears (and skull in the case of the ball).
Relativity theory says that no abnormal experience will be had. The one TV is 10 meters that way and the other is 10 meters the other way. Light moves at c relative to the ship or any other inertial frame, so the two are nicely in sync since it takes light equal time to reach you from each direction.
According to Relativity speed of light can't be exceeded or changed. I am not arguing with that, the images from the two tv travel at the same speed, but what I don't understand is why the direction wouldn't affect the watching experience. For example, on the ISS they shoot two laser beams, one is shot towards the Earth, the other laser is shot towards the opposite direction. The two lasers will travel obviously at the same speed, but which one of them will reach the Earth? Is the direction irrelevant?
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Janus on 13/04/2021 00:16:21
ah ok, who cares about a cosmic particle point of view, I am talking about a freaking human inside a Sci-Fi ship at 98% the speed of light
From the point of the freaking human inside the ship, the ship is stationary by definition. Per the 400 year old Galilean principle of relativity, everything works normally inside the box (ship), so he notices nothing.
You seem to be under the delusion that speed is absolute and it is meaningful for a ship to be going at .98c without giving a reference. The cosmic particle can be the reference.  Anything can. There is no speed I can go where there isn't a planet somewhere that is very very close to stationary relative to me. So Earth is very much moving at .98c relative to some planet 13 billion light years away, and yet we don't see the difference between the various televisions in the pub.

Quote
What is he/she going to experience considering that images and sounds have to make their journey before reaching your eyes/ears (and skull in the case of the ball).
Relativity theory says that no abnormal experience will be had. The one TV is 10 meters that way and the other is 10 meters the other way. Light moves at c relative to the ship or any other inertial frame, so the two are nicely in sync since it takes light equal time to reach you from each direction.
According to Relativity speed of light can't be exceeded or changed. I am not arguing with that, the images from the two tv travel at the same speed, but what I don't understand is why the direction wouldn't affect the watching experience. For example, on the ISS they shoot two laser beams, one is shot towards the Earth, the other laser is shot towards the opposite direction. The two lasers will travel obviously at the same speed, but which one of them will reach the Earth? Is the direction irrelevant?
If the TVs are not moving relative to you, you will see no difference in images coming from either one.  The only way you would see a difference is if one was moving away from you and one was moving towards you.
Relativity say that the speed of light( in a vacuum) is invariant, and  that anyone in an inertial frame ( in this case non-accelerating) will measure light as traveling at c relative to themselves.
So you, in the spaceship would measure the light coming from the TV's as traveling at c relative to yourself. If the TV's are equal distances from you, you will see the same images at the same time from both of them.
Now, for someone that you are traveling at near c relative to would also measure the light from each TV as traveling at c relative to them, and that you would be rushing towards the light emitted by one TV, and running away from the light emitted by the other.   He will however agree with you that the same images from the TV arrive at your eyes at the same moment.
For this to happen, the image from one TV will have had to be emitted before the same image was emitted by the other TV.

Thus for you, both TVs emit the same images at the same time and they arrive at the same time. The emission of the program from the TV are synchronized to each other.  But for the other observer in order for you to observe simultaneous images, the two TV's cannot be in sync with each other.
This is the Relativity of Simultaneity.  Simultaneity is not absolute ( different frames of reference can disagree as whether given events are simultaneous or not). 
While this seems counter-intuitive, and goes against previous notions of how time behaves, it is the way time works in our universe.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: myuncle on 13/04/2021 00:57:10
ah ok, who cares about a cosmic particle point of view, I am talking about a freaking human inside a Sci-Fi ship at 98% the speed of light
From the point of the freaking human inside the ship, the ship is stationary by definition. Per the 400 year old Galilean principle of relativity, everything works normally inside the box (ship), so he notices nothing.
You seem to be under the delusion that speed is absolute and it is meaningful for a ship to be going at .98c without giving a reference. The cosmic particle can be the reference.  Anything can. There is no speed I can go where there isn't a planet somewhere that is very very close to stationary relative to me. So Earth is very much moving at .98c relative to some planet 13 billion light years away, and yet we don't see the difference between the various televisions in the pub.

Quote
What is he/she going to experience considering that images and sounds have to make their journey before reaching your eyes/ears (and skull in the case of the ball).
Relativity theory says that no abnormal experience will be had. The one TV is 10 meters that way and the other is 10 meters the other way. Light moves at c relative to the ship or any other inertial frame, so the two are nicely in sync since it takes light equal time to reach you from each direction.
According to Relativity speed of light can't be exceeded or changed. I am not arguing with that, the images from the two tv travel at the same speed, but what I don't understand is why the direction wouldn't affect the watching experience. For example, on the ISS they shoot two laser beams, one is shot towards the Earth, the other laser is shot towards the opposite direction. The two lasers will travel obviously at the same speed, but which one of them will reach the Earth? Is the direction irrelevant?
If the TVs are not moving relative to you, you will see no difference in images coming from either one.  The only way you would see a difference is if one was moving away from you and one was moving towards you.
Relativity say that the speed of light( in a vacuum) is invariant, and  that anyone in an inertial frame ( in this case non-accelerating) will measure light as traveling at c relative to themselves.
So you, in the spaceship would measure the light coming from the TV's as traveling at c relative to yourself. If the TV's are equal distances from you, you will see the same images at the same time from both of them.
Now, for someone that you are traveling at near c relative to would also measure the light from each TV as traveling at c relative to them, and that you would be rushing towards the light emitted by one TV, and running away from the light emitted by the other.   He will however agree with you that the same images from the TV arrive at your eyes at the same moment.
For this to happen, the image from one TV will have had to be emitted before the same image was emitted by the other TV.

Thus for you, both TVs emit the same images at the same time and they arrive at the same time. The emission of the program from the TV are synchronized to each other.  But for the other observer in order for you to observe simultaneous images, the two TV's cannot be in sync with each other.
This is the Relativity of Simultaneity.  Simultaneity is not absolute ( different frames of reference can disagree as whether given events are simultaneous or not). 
While this seems counter-intuitive, and goes against previous notions of how time behaves, it is the way time works in our universe.

Are lasers beams any exception to this rule? Because I would consider the images from the two tv just like thousands of laser beams shot towards the viewer eyes. And it doesn't need to be a tv, it could be two persons singing and dancing the same tune, one person in front of you and the other person behind you. But let's talk about lasers, maybe easier to discuss and understand, because they are directional. A laser is shot for example from the Earth towards the moon, to measure the distance. If the laser wasn't directed exactly towards the mirror, it will never make its journey back to the Earth. Am I right?
Another example, a ship is travelling at the speed of light (I know it's impossible but just imagine that) and will do a flyby of Earth. This ship will shoot one laser ahead (towards the travel direction), and another laser beam at the back (opposite the travel direction). What would we see from Earth during the flyby? I suppose we would only see one laser trail left from the laser at the back of the ship, but we wouldn't see any beam shot from the front. Isn't this all about direction?
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Janus on 13/04/2021 01:45:39
ah ok, who cares about a cosmic particle point of view, I am talking about a freaking human inside a Sci-Fi ship at 98% the speed of light
From the point of the freaking human inside the ship, the ship is stationary by definition. Per the 400 year old Galilean principle of relativity, everything works normally inside the box (ship), so he notices nothing.
You seem to be under the delusion that speed is absolute and it is meaningful for a ship to be going at .98c without giving a reference. The cosmic particle can be the reference.  Anything can. There is no speed I can go where there isn't a planet somewhere that is very very close to stationary relative to me. So Earth is very much moving at .98c relative to some planet 13 billion light years away, and yet we don't see the difference between the various televisions in the pub.

Quote
What is he/she going to experience considering that images and sounds have to make their journey before reaching your eyes/ears (and skull in the case of the ball).
Relativity theory says that no abnormal experience will be had. The one TV is 10 meters that way and the other is 10 meters the other way. Light moves at c relative to the ship or any other inertial frame, so the two are nicely in sync since it takes light equal time to reach you from each direction.
According to Relativity speed of light can't be exceeded or changed. I am not arguing with that, the images from the two tv travel at the same speed, but what I don't understand is why the direction wouldn't affect the watching experience. For example, on the ISS they shoot two laser beams, one is shot towards the Earth, the other laser is shot towards the opposite direction. The two lasers will travel obviously at the same speed, but which one of them will reach the Earth? Is the direction irrelevant?
If the TVs are not moving relative to you, you will see no difference in images coming from either one.  The only way you would see a difference is if one was moving away from you and one was moving towards you.
Relativity say that the speed of light( in a vacuum) is invariant, and  that anyone in an inertial frame ( in this case non-accelerating) will measure light as traveling at c relative to themselves.
So you, in the spaceship would measure the light coming from the TV's as traveling at c relative to yourself. If the TV's are equal distances from you, you will see the same images at the same time from both of them.
Now, for someone that you are traveling at near c relative to would also measure the light from each TV as traveling at c relative to them, and that you would be rushing towards the light emitted by one TV, and running away from the light emitted by the other.   He will however agree with you that the same images from the TV arrive at your eyes at the same moment.
For this to happen, the image from one TV will have had to be emitted before the same image was emitted by the other TV.

Thus for you, both TVs emit the same images at the same time and they arrive at the same time. The emission of the program from the TV are synchronized to each other.  But for the other observer in order for you to observe simultaneous images, the two TV's cannot be in sync with each other.
This is the Relativity of Simultaneity.  Simultaneity is not absolute ( different frames of reference can disagree as whether given events are simultaneous or not). 
While this seems counter-intuitive, and goes against previous notions of how time behaves, it is the way time works in our universe.

Are lasers beams any exception to this rule? Because I would consider the images from the two tv just like thousands of laser beams shot towards the viewer eyes. And it doesn't need to be a tv, it could be two persons singing and dancing the same tune, one person in front of you and the other person behind you. But let's talk about lasers, maybe easier to discuss and understand, because they are directional. A laser is shot for example from the Earth towards the moon, to measure the distance. If the laser wasn't directed exactly towards the mirror, it will never make its journey back to the Earth. Am I right?
Another example, a ship is travelling at the speed of light (I know it's impossible but just imagine that) and will do a flyby of Earth. This ship will shoot one laser ahead (towards the travel direction), and another laser beam at the back (opposite the travel direction). What would we see from Earth during the flyby? I suppose we would only see one laser trail left from the laser at the back of the ship, but we wouldn't see any beam shot from the front. Isn't this all about direction?
To keep things in the realm of reality, let's say that the ship is moving at 0.999c relative to the Earth.
From the Earth, we would see the forward facing laser travel at c, with the ship chasing close behind.  After one second the front of the laser will only be 1/1000 of a light second ahead of the ship.   
The rear facing laser will also move at c in the opposite direction of the Ship, and after 1 sec will be 1.999 light sec behind the ship.
However, for anyone in the ship, after 1 sec, the front laser will be 1 light sec from the ship and the rear facing laser will also be 1 light sec from the Ship.

One reason it makes no sense to consider the ship as moving at c is that then the Earth observer would de no laser emitted from the Front, and the ship observer would still see the front laser shooting out at c from the ship.  When the ship is moving at less than c relative to the Earth, the ship and Earth might disagree as to how fast the front laser travels away from the ship, but they do both say that it does leave the ship.  This does not lead to the type of physical contradiction that having the ship travel at c produces.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Bored chemist on 13/04/2021 08:56:08
Are lasers beams any exception to this rule?
No.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: geordief on 15/04/2021 09:06:08
Should the prohibition be formulated to state that nothing  with mass may be accelerated to a relative speed greater than c?
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Petrochemicals on 15/04/2021 11:48:51
You've not said if the ship is accelerating or not.

If it is not accelerating, then it is stationary in its own frame and the two movies will be indistinguishable in every way, assuming you're the same distance from each of them and they were started simultaneously relative to the frame of the ship. Nothing is out of sync. Playing tennis will not work in free-fall.

If the ship is accelerating, then you can apply the equivalence principle and say that the experience is the same as watching two screens in a building, one a few floors above you, and one a few floors below you.  If they're started simultaneously in the frame of the building, the one above you will run faster and slowly get out of sync with the one below you. Same thing on the ship. Playing tennis only works if you're horizontal relative to each other, not one above the other, so the tennis thing would be like trying to play tennis in an elevator shaft, which doesn't sound much like tennis.
How does angular acceleration work vis a vis the speed of light. After all the  solar system is under considerable angular acceleration in the galaxy.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Janus on 15/04/2021 16:18:04
You've not said if the ship is accelerating or not.

If it is not accelerating, then it is stationary in its own frame and the two movies will be indistinguishable in every way, assuming you're the same distance from each of them and they were started simultaneously relative to the frame of the ship. Nothing is out of sync. Playing tennis will not work in free-fall.

If the ship is accelerating, then you can apply the equivalence principle and say that the experience is the same as watching two screens in a building, one a few floors above you, and one a few floors below you.  If they're started simultaneously in the frame of the building, the one above you will run faster and slowly get out of sync with the one below you. Same thing on the ship. Playing tennis only works if you're horizontal relative to each other, not one above the other, so the tennis thing would be like trying to play tennis in an elevator shaft, which doesn't sound much like tennis.
How does angular acceleration work vis a vis the speed of light. After all the  solar system is under considerable angular acceleration in the galaxy.
Taking 230,000,000 years to complete an orbit with 28,000 ly in radius doesn't result in a "considerable" amount of acceleration, but a pretty insignificant one.
Locally, any acceleration has no effect on light speed. If you are under acceleration, you still locally measure light as traveling at c.   What can be effected is the "coordinate" speed of light( how fast light seems to move relative to you when it is far from you as measured along the line of acceleration).
Working this out for the orbiting Solar system ( just considering acceleration and not factoring in the difference in gravitational potential), then the coordinate speed for light at the center of the Earth's orbital path would be just 0.00003% faster than at the Solar system( as measured from the Solar system)
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Petrochemicals on 15/04/2021 19:58:37
You've not said if the ship is accelerating or not.

If it is not accelerating, then it is stationary in its own frame and the two movies will be indistinguishable in every way, assuming you're the same distance from each of them and they were started simultaneously relative to the frame of the ship. Nothing is out of sync. Playing tennis will not work in free-fall.

If the ship is accelerating, then you can apply the equivalence principle and say that the experience is the same as watching two screens in a building, one a few floors above you, and one a few floors below you.  If they're started simultaneously in the frame of the building, the one above you will run faster and slowly get out of sync with the one below you. Same thing on the ship. Playing tennis only works if you're horizontal relative to each other, not one above the other, so the tennis thing would be like trying to play tennis in an elevator shaft, which doesn't sound much like tennis.
How does angular acceleration work vis a vis the speed of light. After all the  solar system is under considerable angular acceleration in the galaxy.
Taking 230,000,000 years to complete an orbit with 28,000 ly in radius doesn't result in a "considerable" amount of acceleration, but a pretty insignificant one.
Locally, any acceleration has no effect on light speed. If you are under acceleration, you still locally measure light as traveling at c.   What can be effected is the "coordinate" speed of light( how fast light seems to move relative to you when it is far from you as measured along the line of acceleration).
Working this out for the orbiting Solar system ( just considering acceleration and not factoring in the difference in gravitational potential), then the coordinate speed for light at the center of the Earth's orbital path would be just 0.00003% faster than at the Solar system( as measured from the Solar system)
I think the speed of the  sun in the galaxy is considerable. What about S stars I know they are not 0.66 but a couple of galaxy's with very large black holes passing each other by, I can imagine we will get there.

https://www.cnet.com/news/fastest-ever-star-discovered-orbiting-milky-ways-supermassive-black-hole/#:~:text=Fastest-ever%20star%20discovered%20orbiting%20Milky%20Way%27s%20supermassive%20black,unfathomable%20speed%20of%20nearly%2015%2C000%20miles%20per%20second.

But I would imagine from the magical properties of light as I have learned them, there would be no effect.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Janus on 15/04/2021 23:02:18
You've not said if the ship is accelerating or not.

If it is not accelerating, then it is stationary in its own frame and the two movies will be indistinguishable in every way, assuming you're the same distance from each of them and they were started simultaneously relative to the frame of the ship. Nothing is out of sync. Playing tennis will not work in free-fall.

If the ship is accelerating, then you can apply the equivalence principle and say that the experience is the same as watching two screens in a building, one a few floors above you, and one a few floors below you.  If they're started simultaneously in the frame of the building, the one above you will run faster and slowly get out of sync with the one below you. Same thing on the ship. Playing tennis only works if you're horizontal relative to each other, not one above the other, so the tennis thing would be like trying to play tennis in an elevator shaft, which doesn't sound much like tennis.
How does angular acceleration work vis a vis the speed of light. After all the  solar system is under considerable angular acceleration in the galaxy.
Taking 230,000,000 years to complete an orbit with 28,000 ly in radius doesn't result in a "considerable" amount of acceleration, but a pretty insignificant one.
Locally, any acceleration has no effect on light speed. If you are under acceleration, you still locally measure light as traveling at c.   What can be effected is the "coordinate" speed of light( how fast light seems to move relative to you when it is far from you as measured along the line of acceleration).
Working this out for the orbiting Solar system ( just considering acceleration and not factoring in the difference in gravitational potential), then the coordinate speed for light at the center of the Earth's orbital path would be just 0.00003% faster than at the Solar system( as measured from the Solar system)
I think the speed of the  sun in the galaxy is considerable.
~230 km/sec, which is only 0.00077c
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What about S stars I know they are not 0.66 but a couple of galaxy's with very large black holes passing each other by, I can imagine we will get there.

https://www.cnet.com/news/fastest-ever-star-discovered-orbiting-milky-ways-supermassive-black-hole/#:~:text=Fastest-ever%20star%20discovered%20orbiting%20Milky%20Way%27s%20supermassive%20black,unfathomable%20speed%20of%20nearly%2015%2C000%20miles%20per%20second.
Roughly 0.08c,  which gives a gamma of 1.0033.  In terms of time dilation a difference of ~12 sec per hour.
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But I would imagine from the magical properties of light as I have learned them, there would be no effect.
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Nothing magical about light; it just follows the same rules set down by the universe as everything else.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Petrochemicals on 15/04/2021 23:25:50
]Roughly 0.08c,  which gives a gamma of 1.0033.  In terms of time dilation a difference of ~12 sec per hour.


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You've obviously misplaced a decimal.From the article.
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And astronomers have just discovered the quickest of the lot, clocking its fastest speed around Sgr A* at 8% the speed of light.
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Origin on 16/04/2021 12:19:02
You've obviously misplaced a decimal.From the article.
No, 8% of the speed of light = .08c
Title: Re: Watching, hearing, playing in a spaceship travelling near speed of light
Post by: Petrochemicals on 16/04/2021 23:01:53
You've obviously misplaced a decimal.From the article.
No, 8% of the speed of light = .08c
Sorry, doing it on my phone and not reading it properly. I really should answer more throughly.

 If two S planets are orbiting the centre opposite each other at 10% the speed of light, one in its own frame sees the other accelerating at 20 percent the speed of light . This increaced even more if two super large seperate galaxy's with S planets pass by at close proximity.

Theoretically, the one planet would expect the other to experience relativistic effects, but really its just increaced reaction rates due to increaced gravitation. Orbital angular acceleration of orbits is governed by the gravitational pull.