B Relativity of simultaneity and the balance of the systems

[jartsa]

Haha
As I already said, there are countless examples (at leas to my understanding of the problem) that can be used.
Let's focus on only one

Let's focus on the example with a space station with unfolding solar panels.

Ah but now I want to change it to a space station with panels that are first transparent and then become opaque, liquid crystal panels or similar.

May I do this last change pretty please?

The panels bend a little bit when they become opaque and start absorbing photons. One panel bends first, then the other, then the panels are equally bent, that's what happens in the frame where the space station is in motion.

The photons impart momentum to the panels, that momentum travels to the space station through metal rods or something.

Ok now I have a question:

If in the frame where the space station is in motion two photons hit simultaneously the two panels, does the space station feel the two impulses simultaneously or non-simultaneously?

 

[Sisoeff]

I think what you are missing is that the observation that two events are simultaneous can be agreed upon by all if everyone understands how relativity works. If an observer at A detects two simultaneous events and releases some energy, an observer at B will be able to use his/er understanding of relativity to calculate that two events which B did not observe simultaneously A did observe simultaneously.

Your way of thinking is a bit like standing at a train station confused about how a train can get there at 10:00 if it is somewhere else at 11:00 -- as long as you know how to read the schedule, it shouldn't confuse you!

Thank you, Russ.
You are right that an observer in B can calculate and find out that there are two simultaneous events which release energy, or put the lights on.
(Let's use "lights on" instead of energy, please. Peter made me feel uncomfortable with "release of energy" output)
Must I understand that it is OK for science to have an effect without having corresponding cause in the reference frame?
When we observe the Universe and we don't understand certain effect, can we assume, that the cause of the effect lies in another frame of reference, but which one we would never know.
To me it looks like an open door for great speculations and miss interpretations.

 

[Ibix]

Well, it is logic, and science requires logic.
You didn't tell me whether you understand the idea.
Saying that "If the lights are on they are on." does not gives me any understanding.
What do you mean by that?
What is missing in the scenario.
The fact that the observer does not know why the lights are on, or that they should be on, doesn't change the given scenario.
I already set it for you, and you know that lights goes on as a result of two simultaneous events.
I started from the ladder paradox, which explains relativity of simultaneity, and I'm explaining why I see problem in that explanation.
For better understanding we changed the scenario few time, not in great details, but I thought that it is enough for you guys to understand it.
Non of you even told me what you don't understand, and I don't feel like you have the intention to help me.
Sorry!

I explained what was wrong with your analysis of your balanced barn problem in my first post on this thread. Peter has pointed out the problem with your "touching two sides of a piece of metal" version of the problem. The general point is that it takes time for the effects from an event to propagate, and that ends up meaning that consequences such as "does the barn tip?" are frame indepedent. Everyone agrees that the barn does not tip. They don't necessarily agree on the sequence of all the things that lead to that result. But they do agree on what all those things are, and they agree on the final consequence. If the barn tips according to one observer it tips according to all. Or in my slightly pithier language from earlier, if it tips, it tips.

The general issue with all of your scenarios is that you seem to think that you can build something that will only react to simultaneous events. You can't. You can pick a frame and build something that will only react to events that are simultaneous in that frame. However, if you analyse the device in any other frame you will find that it reacts to events that are separated by some time $\Delta t$, and that $\Delta t$ is exactly the time diffrrence you find in this frame between events that are simultaneous in the first frame.

So yes, I understand your scenario descriptions. I also understand what is impossible about them. I already explained the correct analysis of one of them and Peter has explained another. We are happy to help, but you have to read the help we provide.

 

[Ibix]

Thank you, Russ.
You are right that an observer in B can calculate and find out that there are two simultaneous events which release energy, or put the lights on, which he doesn't see.
(Let's use "lights on" instead of energy, please. Peter made me feel uncomfortable with "release of energy" output)
Must I understand that it is OK for science to have an effect without having corresponding cause in the reference frame?
When we observe the Universe and we don't understand certain effect, can we assume, that the cause of the effect lies in another frame of reference, but which one we would never know.

Every effect has a cause. Observers don't necesarily agree on the order of all of the events leading up to something (except those that are causally related themselves), but they agree that all of the same things happened.

Your question about which frame something happened in has no meaning. A frame is just a point of view. Things happen. They don't "happen in a frame". It's like asking whether that chair exists when I'm moving. Or implying that it exists for you (because you are stationary) but not me because I'm walking. That's not a description of the universe we live in.

Please see my last post. You seem to think itvis possible to detect simultaneity. You can only pick a frame and detect whether two events were simultaneous in that frame.

 

[A.T.]

does the space station feel the two impulses simultaneously or non-simultaneously?

What does this mean?

 

[Nugatory]

Must I understand that it is OK for science to have an effect without having corresponding cause in the reference frame?
When we observe the Universe and we don't understand certain effect, can we assume, that the cause of the effect lies in another frame of reference, but which one we would never know.
To me it looks like an open door for great speculations and miss interpretations.

You are misunderstanding what a frame is - a frame is no more than a convention for assigning coordinates to events. When I say that a chair is one meter to my left, and someone else says that the chair is two meters to the right of the table, we are using different frames. Thus, it makes no sense to say that something "lies in another frame", or is "in" this frame but not that one. Everything is always "in" all frames always, just as the chair is there no matter what numbers I use to describe its position.

 

[Nugatory]

If in the frame where the space station is in motion two photons hit simultaneously the two panels, does the space station feel the two impulses simultaneously or non-simultaneously?

The impulses travel through the structure of the space station at the speed of sound. In general, they will reach different points in that structure at different times because they have to travel different distances from the points of impact.

However, if both impulses arrive at a given point at the same time according to measurements carried out using anyone frame, they will arrive at that point at the same time using measurements carried out using all frames.

 

[jartsa]

What does this mean?

By this question:

If in the frame where the space station is in motion two photons hit simultaneously the two panels, does the space station feel the two impulses simultaneously or non-simultaneously?

I mean this:
We have a moving rod. Two sound waves start to propagate towards the center of the rod when the two ends of the moving rod are hit simultaneously by two photons, simultaneously in the frame where the rod is moving. The two hits are not simultaneous in the rod frame, because that frame where the hits are simultaneous is the frame where the rod is in motion. Do those sound waves that started off at different times in the rod frame reach the center of the rod at the same time?

As the answer to that question is no, we conclude that the two sound waves spend different times traveling from one end of the rod to the center of the rod, in that frame where the two ends where hit simultaneously, and as we remember that frame was the frame where the rod was in motion.

 

[russ_watters]

Must I understand that it is OK for science to have an effect without having corresponding cause in the reference frame?
When we observe the Universe and we don't understand certain effect, can we assume, that the cause of the effect lies in another frame of reference, but which one we would never know.

Of course! Most of what happens in the universe doesn't happen here, we only observe it from here!

To me it looks like an open door for great speculations and miss interpretations.

I don't see how - as long as you keep the reference frames straight and don't play loose with the wordings of the descriptions, it really is not difficult to interpret relativity of simultaneity. Most of your scenarios suffer from the same problem: you are wording them poorly which makes them tough to interpret. What bothers me is that you don't seem to care about getting them right (and are actually getting upset that people are trying to help you correct them! ) before jumping to the next poorly worded scenario.

 

[Nugatory]

By this question:I mean this:
We have a moving rod. Two sound waves start to propagate towards the center of the rod when the two ends of the moving rod are hit simultaneously by two photons, simultaneously in the frame where the rod is moving. The two hits are not simultaneous in the rod frame, because that frame where the hits are simultaneous is the frame where the rod is in motion. Do those sound waves that started off at different times in the rod frame reach the center of the rod at the same time?

Whereever in the rod the sound waves meet, it will be the same in all frames. See post 57 above.

Do remember, however, that the speed of the sound waves is different in different frames.

 

[Sisoeff]

Of course! Most of what happens in the universe doesn't happen here, we only observe it from here!

I don't see how - as long as you keep the reference frames straight and don't play loose with the wordings of the descriptions, it really is not difficult to interpret relativity of simultaneity. Most of your scenarios suffer from the same problem: you are wording them poorly which makes them tough to interpret. What bothers me is that you don't seem to care about getting them right (and are actually getting upset that people are trying to help you correct them! ) before jumping to the next poorly worded scenario.

Hi Russ,
Thank you for taking from your time to answer my comments.
Everything of what happens in the Universe has its cause in our frame of reference. We may not see the cause, but it is there, because there is no effect without cause.
I hope that you'll agree with this base law of Physics, without referring to theories.
As for now all theories must account for this law (Causality) - cause and effect.
The presented by me problem (I see it as such) is treating this exact matter.
To me, and according to causality, it is illogical to say that in our frame of reference we can have an effect without having the cause.
According to Special Relativity, whether two spatially separated events occur at the same time is not absolute, but depends on the observer's reference frame.
Which contradicts the law of cause and effect.
How? (explaining my understanding again)
In the ladder paradox thought experiment, if we set the simultaneously flapping doors to close an electrical circuit, thus powering an electrical lamp, we will have in the garage reference frame the cause (simultaneously closing doors) and the effect light from the electrical lamp.
In the ladder reference frame we will not have simultaneity, because it does pass through the garage, but will have the light from the electrical lamp.
So, the cause for the light in the ladder's reference frame is missing, because there is no simultaneity in the ladder reference frame (it passes through the garage), but the effect from the missing cause is present(!)
To me it is obvious that this is in a conflict with Causality (cause and effect)
If you now a way to satisfy the law of cause and effect in the above situation, please share.

 

[jartsa]

Whereever in the rod the sound waves meet, it will be the same in all frames. See post 57 above.

Do remember, however, that the speed of the sound waves is different in different frames.

And the speed of sound waves with different directions is different in all frames except the medium frame.

So I suggest as a solution to the garage doors paradox that the anisotropy of the speed of sound in the garage doors cancels out the non-simultaneity of opening of the doors.

 

[Sisoeff]

You are misunderstanding what a frame is - a frame is no more than a convention for assigning coordinates to events. When I say that a chair is one meter to my left, and someone else says that the chair is two meters to the right of the table, we are using different frames. Thus, it makes no sense to say that something "lies in another frame", or is "in" this frame but not that one. Everything is always "in" all frames always, just as the chair is there no matter what numbers I use to describe its position.

I understand very well what a reference frame is, and I should probably put quotes around that words, because all this conversation comes from my understanding that Special Relativity treats the reference frames as boxes, where in one box can "lie" simultaneity and in the other it will be missing.
Follow the conversation to get the context. See my previous comment.
And thank you for your time. I appreciate it

 

[A.T.]

if we set the simultaneously flapping doors to close an electrical circuit, thus powering an electrical lamp, we will have in the garage reference frame the cause (simultaneously closing doors) and the effect light from the electrical lamp. In the ladder reference frame we will not have simultaneity, because it does pass through the garage, but will have the light from the electrical lamp.

This was addressed in post #45 already.

 

[Sisoeff]

This was addressed in post #45 already.

Did you comment on it? I missed it.
My apologies, I'll find it now.

 

[Ibix]

If you now a way to satisfy the law of cause and effect in the above situation, please share.

As with your other examples, you take into account the travel time of the signals - the electricity in this case. You will find that your system detects simulyaneity in one frame and non-simultaneity in all others. I think I've pointed this out three times now...

 

[PeterDonis]

the cause for the light in the ladder's reference frame is missing, because there is no simultaneity in the ladder reference frame

You are not reading our responses. I have already said, multiple times now, that simultaneity is not a physical thing, and that you should not be focusing on it. And others have said that a "frame" is not a physical thing, it's just a way of labeling events, and events are "present" in all frames, they aren't "present" in some frames but not others.

Let me say the key points again, with emphasis: Simultaneity is not a physical thing. It is not a "cause" of anything. The true cause of the light going on in your scenario is not "simultaneity"; it's something else. And that something else is present in all frames, because all events are present in all frames.

Please read and re-read the above until it sinks in. Then go back over previous posts in this thread and find where we have told you, repeatedly, what the "something else" is that is the true cause of the light going on.

At this point I am closing this thread, because the root question has been answered repeatedly. Sisoeff, if you still have questions after doing what I suggest above, feel free to PM me.