Right. It is only against an unarticulated background that representations can make sense to us.
What you see as a light sphere is seen by everyone else as a light ovoid if they measure you to be moving.
You will also find that a flash of light at the centre of your sphere hits the walls simultaneously but, owing to the relativity of simultaneity other observers will see the flash hitting the walls of the ovoid at different times.
Here is a good intro to SR: https://en.wikibooks.org/wiki/Special_Relativity
Flannel Jesus requested that I “ping” him in this thread so that he could answer my question about Special Relativity and its second postulate.
My question to Flannel is: The second postulate of Special Relativity states that the speed of light is constant. If a light is emitted from the center of a cube in motion in space, will the light hit the center of each wall at the same time in the cube?
I think that, in Relativity, you’ve got it right - the light does not hit all the walls at the same time.
But in the cube frame of reference the distances from the center of the cube to the center of the walls are all the same, correct?
Yes, and in the cube frame of reference the light does hit the walls at the same time. In relativity.
You just stated that the light does not hit the walls at the same time. Now you are saying the light does hit the walls at the same time.
You are in the cube. You have receivers at the center of each wall. You send a light from the center of the cube. Does the light reach the receivers at the same time?
When I google Relativity of Simultaneity, I get this:
The receivers are separated in space. Whether the light hits them at the same time, as per the quoted sentence above, is not absolute, but depends on the observer’s reference frame, in relativity.
In the reference frame of the box, assuming it’s travelling in an inertial frame (ie not accelerating), the light will hit all sides simultaneously.
In another, different inertial reference frame, the light will not hit all sides simultaneously.
This is totally false.
You are in the cube. If the lights hit all the receivers at the same time they will all have the same timestamp as to when the light hit each receiver. If the light hit them at different times then they will all have different timestamps. There is only one reality, they either have the SAME timestamps, or they have different timestamps.
The receivers don’t suddenly change from “the same times” to “different times” after the fact depending on who you ask. They either are all the same for all, or they are different for all.
In relativity:
A “timestamp” isn’t an objective feature of reality. A timestamp is measured by something - perhaps a clock of some sort. In relativity, both the box frame of reference and the non-box frame of reference will actually predict the same things about the clocks on the four walls, they’ll just predict those things for different reasons.
In the box frame, the four clocks are, presumably, synchronized. They will read the same time because the light hits four synchronized clocks at the same time.
In the non-box frame, the four clocks are not synchronized. They are offset from each other. After the light hits each one, they will, funnily enough, read the same time as each other, because there’s a way to hit four unsynchronized watches at four (or three, I guess - the two middle clocks are probably supposed to remain in sync I guess) different times, such that all the clocks have the same reading.
So you get the same timestamp from the clocks no matter what your frame of reference is. It’s just, the clocks are synced in one frame and not synced in another.
It’s not a matter of “what time was it” it’s a matter of “same on all” or “different on all”. What you are trying to say is that the receivers will claim to be “the same” in the cube, but will claim to be “different” in some other frame of reference. That is impossible.
Look at my pic in the OP. The distances are noted at each time. It is impossible for the light to have reached each receiver at the same time in the cube. That would mean the distances and times would not add up to 299,792,458 m/s. The light sphere has a center which does not travel in space. The center of the cube has a center that travels a distance away from the center of the light sphere.
There is NO WAY you can say the light hit all the receivers at the same time in the cube, unless the cube had an absolute zero velocity in space, which is shown to be not true in the pic.
I’m not sure what you mean by this exactly. What does it mean for the receivers to claim to be something? Do you just mean, if we stop the clocks when they’re hit with the light, what will the clocks read? Or do you mean something else?
Right, there is one clock in the cube frame of reference. All the clocks on the receivers tick as one, just like all the clocks in your living room tick as one.
So if the light sphere hits all the receivers simultaneously all the receivers will have the exact same timestamp as to when the light hit them. They will all have the same timestamp on them as to when the light hit each one. That is a reality that they were hit at the same time, simultaneously.
Why one clock? Why not four clocks, one for each wall of the box? I don’t think I understand the scenario you’re trying to build here.
So in your living room it’s 12:00 on one clock and 12:01 on the other clock?
I don’t understand the point of your question. I’m asking you why you would use one clock instead of four clocks. Can you explain it without rhetorical questions back to me? I would like to understand.
I don’t mean there is just one physical clock in the cube, as I stated all the clocks tick as one. Each receiver has its own clock and all the clocks in the cube are synchronized to tick as one clock. If I am at one receiver and it reads 12:05:01, then I know for sure that the other theoretically perfect clocks read 12:05:01 at that same time.
They all tick as one and read as one.
Sure, in the reference frame of the box they are all synchronized, that’s perfectly fine. Four clocks synchronised in that reference frame.
Right, so then you send a light from the center of the cube. There is a reality of either the light reached all the receivers at the same time, or it reached all the receivers at different times. Agree?
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Relative = from our/a perspective… so the only measurable change, being that of distance x ¿speed?
Pardon my intrusion