A not so small discrepancy in Relativity of Simultaneity

[Strange]

11 minutes ago, Truden said:

As I said in the OP, do not think of the event as "will not happen".

In the theory of relativity, it cannot happen in one frame of reference and not the other. Therefore the error is in your thought experiment.

You have been given the probable reason. I don't know what else you want.

12 minutes ago, Truden said:

What math can we use here?

Work out what will happen to those extra bits you have added to the doors when accelerated at the rates required by the thought experiment. (They will probably be destroyed.)

[Truden]

34 minutes ago, Strange said:

In the theory of relativity, it cannot happen in one frame of reference and not the other. Therefore the error is in your thought experiment.

You have been given the probable reason. I don't know what else you want.

Work out what will happen to those extra bits you have added to the doors when accelerated at the rates required by the thought experiment. (They will probably be destroyed.)

 

"In the theory of relativity, it cannot happen" is not a valid argument, since we question the theory of relativity.
I don't need to work out anything since the original Ladder Paradox experiment doesn't care about the technicality. Do you think that any door system can allow for a door to move with speed close to the speed of light, then instantly stop and move back with the same speed? I don't think so.
Think of my experiment as constructed in order the doors to stop, when they touch at the red points. Think of the trapezoid part of the door as a solid on the whole length, if it will make it more comfortable for you from a techincal point of view. And instead of the doors stopping on a door frame, take it that they stop on each other, on that short side of the trapezoid, where the red dots are.
And again, the experiment can be replicated in many different ways, not using doors, garage, and ladder. I just thought that this way of presenting it would be easier since everyone already knows the Ladder Paradox.

[Strange]

1 minute ago, Truden said:

"In the theory of relativity, it cannot happen" is not a valid argument, since we question the theory of relativity.

It is a valid argument. The theory is mathematically consistent therefore you can't produce inconsistent results. Relativity might be wrong (it isn't) but it would still be consistent.

I will let someone else try and explain your errors.

[Truden]

1 minute ago, Strange said:

It is a valid argument. The theory is mathematically consistent therefore you can't produce inconsistent results. Relativity might be wrong (it isn't) but it would still be consistent.

I will let someone else try and explain your errors.

 OK. 
To make it even easier for that someone else, let's take the ladder out of the garage path. Let's assume that it doesn't go through the garage. 
For the ladder, the closing of the doors will still be not simultaneous due to its high speed.
Now we can lower the speed of the closing doors, to meet your requirements for rigidity and door speed.
Yet we'll still have a missing event in the ladder reference frame. And as I said, if the third event triggers a bomb,  the garage will blow, but will still be intact in the ladder FoR.
Why? Because in that FoR the event is missing.
 

[J.C.MacSwell]

OK. Lets assume a configuration with no faster than light movements or transmissions. (Sorry no drawing but say two capital "L" shapes, rotated and hinge connected by there tops in mirror image fashion. Verticals of the Ls now horizontal and much longer than their bottoms which will be the doors. Hinge connection such that the thickness of the Ls can lose or gain contact on the underside, "shut points",  which is the exactly halfway point of barn ) So movement will mostly be vertical at the doors despite the rotation.

In the frame of the barn:

the contracted ladder approaches at near light speed. Both doors are open, connected at the central hinge, but not at the "shut points" immediately below it.

ladder enters barn

When it gets to the middle (centre point of ladder right below hinge) doors shut simultaneously. Doors do this as rigidly as possible in this frame. (exact rigidity is not possible for any accelerations in SR in the direction of acceleration) All points of the door are timed to move to allow this (near rigid movement), so no FTL transmission is necessary.

What does this look like in the frame of the ladder? Here it is:

Contracted barn  with open doors near light speed approaches ladder

The back door of the barn shuts, then opens

when the hinge reaches the midpoint of the ladder the hinge shuts (simultaneously agreed in both frames)

when the front door passes the end of the ladder it shuts then opens 

Note how "unrigid" the doors seem in this frame, despite being almost perfectly rigid in the barn frame.

Edit:  This is what I was referring to in my earlier post, for any given point* in one frame you can construct for agreed simultaneity at one point* and time  only on the other frame.

point* is actually a plane perpendicular to direction of relative travel

I chose to make this point of agreement coincide at the hinge and mid point of ladder...nice symmetrical snapshot of the setup in the barn frame...very distorted barn in the other with both doors open and hinge closed

Edited November 18, 2017 by J.C.MacSwell

[Truden]

6 minutes ago, J.C.MacSwell said:

OK. Lets assume a configuration with no faster than light movements or transmissions. (Sorry no drawing but say two capital "L" shapes, rotated and hinge connected by there tops in mirror image fashion. Verticals of the Ls now horizontal and much longer than their bottoms which will be the doors. Hinge connection such that the thickness of the Ls can lose or gain contact on the underside, "shut points",  which is the exactly halfway point of barn ) So movement will mostly be vertical at the doors despite the rotation.

In the frame of the barn:

the contracted ladder approaches at near light speed. Both doors are open, connected at the central hinge, but not at the "shut points" immediately below it.

ladder enters barn

When it gets to the middle (centre point of ladder right below hinge) doors shut simultaneously. Doors do this as rigidly as possible in this frame. (exact rigidity is not possible for any accelerations in SR in the direction of acceleration) All points of the door are timed to move to allow this (near rigid movement), so no FTL transmission is necessary.

What does this look like in the frame of the ladder? Here it is:

Contracted barn  with open doors near light speed approaches ladder

The back door of the barn shuts, then opens

when the hinge reaches the midpoint of the ladder the hinge shuts (simultaneously agreed in both frames)

when the front door passes the end of the ladder it shuts then opens 

Note how "unrigid" the doors seem in this frame, despite being almost perfectly rigid in the barn frame.

 I don't get your point with the rigidity, but you should abandon the rigidity argument.
I already said many times; this scenario can be replicated in many different ways without garage doors and ladder. But if you want it with doors, I can make them move vertically and still have the touch event. Or we can put two very short pins on the hinges, where the speed is the lowest or many, many different ways to satisfy your concerns.
But your concerns must be about the logical output, not the technicalities, because the original Ladder Paradox does not meet any technical requirements, but is still a valid thought experiment. 
In my previous comment, I said that we can place the ladder outside the garage and lower down the speed of the doors to whatever speed suits you. The relativity of simultaneity does not depend on the speed of the doors. Even if they move with 100miles per hour, in the ladder FoR they'll still not close simultaneously. 
We are not interested in whether the ladder will pass through the garage, but whether the event is missing in its reference frame. In that context, we can create thousands of experiments to show that in one of the reference frames an event is missing.
 

[J.C.MacSwell]

24 minutes ago, Truden said:

 I don't get your point with the rigidity, but you should abandon the rigidity argument.
I already said many times; this scenario can be replicated in many different ways without garage doors and ladder. But if you want it with doors, I can make them move vertically and still have the touch event. Or we can put two very short pins on the hinges, where the speed is the lowest or many, many different ways to satisfy your concerns.
But your concerns must be about the logical output, not the technicalities, because the original Ladder Paradox does not meet any technical requirements, but is still a valid thought experiment. 
In my previous comment, I said that we can place the ladder outside the garage and lower down the speed of the doors to whatever speed suits you. The relativity of simultaneity does not depend on the speed of the doors. Even if they move with 100miles per hour, in the ladder FoR they'll still not close simultaneously. 
We are not interested in whether the ladder will pass through the garage, but whether the event is missing in its reference frame. In that context, we can create thousands of experiments to show that in one of the reference frames an event is missing.
 

...and with it...Special Relativity...so you are left with creating your "thousands of (thought) experiments", based on what?

All you have come up with is that assuming rigidity is not consistent with SR...and we knew that already.

[Strange]

19 minutes ago, Truden said:

I don't get your point with the rigidity, but you should abandon the rigidity argument.

It is a bit pointless trying to ignore the explanation and then saying there is no explanation.

The reason it is relevant is because you are using a mechanical structure to transfer information (the time at which the door becomes fully closed) from the two doors. This is no different from using flashes of light when the doors are closed. The flashes would be simultaneous in one frame of reference and not another. Your mechanical arrangement will not change that: neither frame of reference will see the rods/door-extensions/whatever meet but they will have different explanations for why not. In one case it will be because the doors closed at different times, in the other case it will be because the mechanical structure was distorted (that will be true in both cases, but is only important in one).

Your new version of the experiment where you just close the two doors with no worry about the ladder passing through isn't really relevant because, obviously, if you keep the doors closed then at some point everyone will see them as closed. The measurement of simultaneity needs to be related to an event (e.g. the time at which the doors become fully closed). This event will happen at a different time in each frame. There is no way of communicating information instantly between the two doors; nor is there any way of communicating the information in such a way that the communication will take the same time in both frames of reference.

29 minutes ago, Truden said:

But your concerns must be about the logical output

Your "logical" conclusion is wrong. You just need to make the effort to understand why. As you are unwilling to do this, this thread is probably pointless.

Also, as you are clearly trying to contradict relativity, I shall suggest it is moved to the speculations forum. Then, if you just continue with unsupported assertions, it will probably be closed.

[Truden]

 

17 minutes ago, Strange said:

It is a bit pointless trying to ignore the explanation and then saying there is no explanation.

The reason it is relevant is because you are using a mechanical structure to transfer information (the time at which the door becomes fully closed) from the two doors. This is no different from using flashes of light when the doors are closed. The flashes would be simultaneous in one frame of reference and not another. Your mechanical arrangement will not change that: neither frame of reference will see the rods/door-extensions/whatever meet but they will have different explanations for why not. In one case it will be because the doors closed at different times, in the other case it will be because the mechanical structure was distorted (that will be true in both cases, but is only important in one).

Your new version of the experiment where you just close the two doors with no worry about the ladder passing through isn't really relevant because, obviously, if you keep the doors closed then at some point everyone will see them as closed. The measurement of simultaneity needs to be related to an event (e.g. the time at which the doors become fully closed). This event will happen at a different time in each frame. There is no way of communicating information instantly between the two doors; nor is there any way of communicating the information in such a way that the communication will take the same time in both frames of reference.

Your "logical" conclusion is wrong. You just need to make the effort to understand why. As you are unwilling to do this, this thread is probably pointless.

Also, as you are clearly trying to contradict relativity, I shall suggest it is moved to the speculations forum. Then, if you just continue with unsupported assertions, it will probably be closed.

I don't think that you read my answers to you and the rest.
There is no argument about the door touching on the short side of the trapezoid. THEY TOUCH!
It is given as part of the experiment construct. You cannot say that the doors don't touch. THEY TOUCH.
There is no walls or door frames to stop the doors. They meet and THEY TOUCH.
And don't tell me that they'll crash into each other, please.
I still try to figure out how the walls of the original Ladder Paradox resist such impacts from the doors 

Edited November 18, 2017 by Truden

[Strange]

3 minutes ago, Truden said:

There is no argument about the door touching on the short side of the trapezoid. THEY TOUCH!

If they do, then they do in both frames of reference and the question then is: When do they touch? The instant at which they come together will be different for each frame of reference.

Edited November 18, 2017 by Strange

[Truden]

Just now, Strange said:

If they do, then the question is: When? The instant at which they come together will be different for each frame of reference.

Oh, we are going somewhere. Thank you.
The point is that the doors can only touch when they are closing simultaneously and since there is no simultaneity in the ladder FoR, they'll never touch in that reference frame.  

[J.C.MacSwell]

2 minutes ago, Truden said:

Oh, we are going somewhere. Thank you.
The point is that the doors can only touch when they are closing simultaneously and since there is no simultaneity in the ladder FoR, they'll never touch in that reference frame.  

Why not? That event takes place in that frame if it takes place in any...just not at the same times with respect to that frame as either door is closed. (nether door is closed at the same time in that frame)

[Strange]

16 minutes ago, Truden said:

The point is that the doors can only touch when they are closing simultaneously and since there is no simultaneity in the ladder FoR, they'll never touch in that reference frame.  

You can't have it both ways. You just said that the ladder is no longer there and the doors are closed for a long period of time. Therefore they will appear to be closed in both frame of reference. I can close the front and back door of my house simultaneously (e.g. with a bit of string tied to each) and walk back and forth between them to see they are both closed at the same time. Another frame of reference will see them both closed. But will disagree about the time at which they both closed. 

It doesn't matter how you arrange to communicate the instant of closing between the two doors: beams of light, rods, odd shaped extensions to the doors. That mechanism will be triggered at different times in each frame of reference.

If, as in the ladder version, the doors close and open really quickly then there will be no "clap" in either frame. If there is a clap, then it will happen at different relative times in each frame of reference.

Edited November 18, 2017 by Strange

[Truden]

OK, let see when the event happens in the ladder FoR.

[J.C.MacSwell]

3 minutes ago, Truden said:

OK, let see when the event happens in the ladder FoR.

It happens with the ends of the ladder sticking out each door, one about to be shut, the other already shut and reopened.

[Strange]

4 minutes ago, Truden said:

OK, let see when the event happens in the ladder FoR.

Yep. Please show your working.

[Truden]

1 minute ago, J.C.MacSwell said:

It happens with the ends of the ladder sticking out each door, one about to be shut, the other already shut and reopened.

Incorrect. Here is the image of the ladder FoR:

The doors do not meet until the ladder is out.

5 minutes ago, Strange said:

Yep. Please show your working.

There is nothing to show. The doors do not touch in the ladder FoR.
You show me because you are arguing that they'll touch.

[Strange]

12 minutes ago, Truden said:

There is nothing to show. The doors do not touch in the ladder FoR.
You show me because you are arguing that they'll touch.

Burden of proof. You claim the theory is wrong. It is up to you to actually demonstrate this is the case. Drawing made up diagrams won't do it. I could draw a diagram of a free falling lift with someone juggling kittens in it, and claim it disproves the equivalence principle behind GR. But obviously it doesn't.

 

Edited November 18, 2017 by Strange

[J.C.MacSwell]

7 minutes ago, Truden said:

Incorrect. Here is the image of the ladder FoR:

The doors do not meet until the ladder is out.

There is nothing to show. The doors do not touch in the ladder FoR.
You show me because you are arguing that they'll touch.

If you would kindly provide a drawing with both doors open, ladder sticking out each end, and the hinge joining the doors touching closed halfway between them you can save us the trouble.

[Truden]

2 minutes ago, Strange said:

Burden of proof. You claim the theory is wrong. It is up to you to actually demonstrate this is the case. Drawing made up diagrams won't do it. I could draw a diagram of a free falling lift with someone juggling kittens in it, and claim it disproves the equivalence principle behind GR. But obviously it doesn't.

 

Do you even understand what are you saying  
I'm providing the proof, and you have to show the error.

[J.C.MacSwell]

2 minutes ago, Truden said:

Do you even understand what are you saying  
I'm providing the proof, and you have to show the error.

The error is your thinking the hinge area cannot be closed when the ladder is midway in it's path through the barn, given that you set it as an assumption in the other frame.

[Truden]

4 minutes ago, J.C.MacSwell said:

If you would kindly provide a drawing with both doors open, ladder sticking out each end, and the hinge joining the doors touching closed halfway between them you can save us the trouble.

I don't understand your request.
I provided everything you need. 
I gave you the Wikipedia image for the ladder FoR.
What else do you need?
You have to understand that in a frame of reference where simultaneity is missing, we cannot have a touching event.
It's as simple as that. 
 

Just now, J.C.MacSwell said:

The error is your thinking the hinge area cannot be closed when the ladder is midway in it's path through the barn, given that you set it as an assumption in the other frame.

Irrelevant. Study the Ladder Paradox.

[J.C.MacSwell]

2 minutes ago, Truden said:

I don't understand your request.
I provided everything you need. 
I gave you the Wikipedia image for the ladder FoR.
What else do you need?
You have to understand that in a frame of reference where simultaneity is missing, we cannot have a touching event.
It's as simple as that. 
 

The guy on the ladder simply won't have time to propose to the girl in the barn...I will give you that

...but the hinge still touches with respect to all frames if it does in any.

[Truden]

8 minutes ago, J.C.MacSwell said:

The guy on the ladder simply won't have time to propose to the girl in the barn...I will give you that

Ha-ha 
Nice touch.

8 minutes ago, J.C.MacSwell said:

...but the hinge still touches with respect to all frames if it does in any.

I don't know what are you saying and which hinges do you mean.
If you refer to the trapezoid sides of the doors, they'll never touch, because, in the ladder frame of reference, each door closes and opens while the other is open.
That is required by the SR. It is explained in the original Ladder Paradox.

Edited November 18, 2017 by Truden

[J.C.MacSwell]

5 minutes ago, Truden said:

 

I don't know what are you saying and which hinges do you mean.
If you refer to the trapezoid sides of the doors, they'll never touch, because, in the ladder frame of reference, each door closes and opens while the other is open.
That is required by the SR. It is explained in the original Ladder Paradox.

In the ladder frame the connection/touching near the hinge (red points) happens halfway between the time the back door opens then closes, and when the front door opens then closes. It will seem like the system connecting the doors is quite flexible, even if it isn't in the barn frame.