# Special Relativity nonsense

So at the moment they passed each other according to the person at N1 of ship1, according to the person at T2 of ship2 he hasn't yet reached the person at N of ship1. How is that possible?
Wait a minute. What is this "moment they passed each other" event that you're referring to? Be specific. Are you talking about the moment when T1 and N2 are aligned, or the moment when N1 and T2 are aligned? Those are different moments, in both frames.
I am referring to the moment that N1 and T2 are aligned. Because N1 has already passed T2 and also N1 has not yet reached T2 that means that there was a moment in the past when N1 and T2 were lined up according to the observer at N1 and N1 had not yet reached T2 according to the observer at T2.

I am referring to the moment that N1 and T2 are aligned.
"Moment" in whose reference frame? You did not specify.
There is no "real" reference frame. Only those of the observers, and they may not agree.

The moment that N1 and T2 are aligned according to the observer at N1, N1 and T2 are not aligned according to the observer at T2. This is impossible. It is impossible for the observer at N1 to look down and see the observer at T2 and yet at the same time the observer at T2 can't look up and see the observer at N1.

The moment that N1 and T2 are aligned according to the observer at N1, N1 and T2 are not aligned according to the observer at T2. This is impossible. It is impossible for the observer at N1 to look down and see the observer at T2 and yet at the same time the observer at T2 can't look up and see the observer at N1.

Look at the words you are using:

"...at the same time..."

The whole point of relativity of simultaneity is that you cannot assume events occur "... at the same time..." according to different observers.

As JamesR said:
What is this "moment they passed each other" event that you're referring to? Be specific. Are you talking about the moment when T1 and N2 are aligned, or the moment when N1 and T2 are aligned? Those are different moments, in both frames.

It is true to say that "at the moment that T1 and N2 are aligned, T2 has already passed N1, according to an observer on ship 1". It is also true to say "at the moment that T1 and N2 are aligned, N1 has not yet passed T2, according to an observer on ship 2".

There is no inconsistency in this, because observers on ship 1 and ship 2 do not share the same notion of simultaneity.

The moment that N1 and T2 are aligned according to the observer at N1, N1 and T2 are not aligned according to the observer at T2. This is impossible.
That's because you're wrong.

N1 and T2 only align at one particular time in the frame of ship 1, and at one particular time in the frame of ship 2. Both ships agree that N1 and T2 are only aligned at one time (on each of their clocks).

It is impossible for the observer at N1 to look down and see the observer at T2 and yet at the same time the observer at T2 can't look up and see the observer at N1.
I agree. Both ships agree that when N1 and T2 are aligned, observers on the ships at N1 and T2 can see one another.

Zeno:

All this was explained to you over a year ago, in exquisite detail by Janus. Did you read back over the thread before reopening it for this year's effort? Or did you just press your mental "reset" button and forget that this stuff was carefully and patiently explained for your benefit?

You've had over a year to digest the information that was given to you. But here you are back again, still stuck on the same problem. In the past year, you could have purchased or got some introductory relativity textbooks out of a library, looked at introductory relativity on the web, sat down with somebody who understands relativity to help you work through the problem. Didn't you do any of those things? Why won't you do any work, if you want to learn this stuff? Even when people spoon feed you, you make no progress.

When all is said and done, I think you should probably recognise that relativity is beyond your capacity to understand, and give up. After all, you've been struggling with this stuff literally for years (are we up to a decade or more, yet?). The average undergraduate student in physics usually can manage to understand these issues in a few weeks, but it's been years and you've made no progress. Maybe physics just isn't your thing. Why not take up interpretive dance, or something, instead?

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Ship1 at rest on top.
Code:
``````       T----------------------N
<----- N----------T``````
Ship2 at rest at bottom.
Code:
``````T----------N ----->
N--------------------T``````
Because N1 has already passed T2 according to N1 there was a moment in the past when the observer at N1 could look down and see the observer at T2.
Because N1 has not yet reached T2 according to the observer at T2 there wasn't a moment in the past when the observer at T2 could look up and see the observer at N1.
This is impossible.

N1 and T2 only align at one particular time in the frame of ship 1, and at one particular time in the frame of ship 2. Both ships agree that N1 and T2 are only aligned at one time (on each of their clocks).
This also must be the same moment in both frames of reference. If you follow special relativity, the event of N1 lining up with T2 occurs at different times in the different reference frames as I have shown above. This is impossible.

Because N1 has already passed T2 according to N1 there was a moment in the past when the observer at N1 could look down and see the observer at T2.
In which frame? You can't mix frames. You need to specify whose "moments" (i.e. whose time) you're using. This sloppiness has been a constant characteristic of your "work" with relativity forever. How do you ever expect to understand it if you forget to pay attention to which reference frame you're using? Relativity is all about translating from one frame to another.

In your top picture, T1 is aligned with N2. T2 passed N1 some time in the past, according to the observer on ship 1.
In your bottom picture, T1 is aligned with N2, again. N1 has yet to pass T2, according to the observer on ship 2.

I've bolded the observers in each case, to draw your attention to the relevant frames. You even drew the pictures yourself and labelled them "Ship 1 at rest on top" and "Ship 2 at rest at bottom". That is, two pictures, one drawn from the perspective of ship 1 and one drawn from the perspective of ship 2.

So, let's correct your statements:

"Because N1 has already passed T2 according to N1 there was a moment in the observer 1's past when the observer at N1 could look down and see the observer at T2, according to the observer on ship 1."

And:

"Because N1 has not yet reached T2 according to the observer at T2 (i.e. as measured by the observer on ship 2), there wasn't a moment in the observer 2's past when the observer at T2 could look up and see the observer at N1."

This is impossible.
What's impossible about it? You have two different observers. One sees T1 and N2 align before T2 and N1; the other sees T2 and N1 align before T1 and N2. They do not agree that the two alignments happen in the same time order.

Get it yet?

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This also must be the same moment in both frames of reference.
The phrase "the same moment in both frames of reference" is a meaningless phrase. You're talking about two observers with independent conceptions of time. You can't compare "moments" in the two frames. You can only compare events. The observers do not share "moments", except in some kind of vague, ill-defined sense in which you're using the term "moment" to refer to a specific event in spacetime.

If you follow special relativity, the event of N1 lining up with T2 occurs at different times in the different reference frames as I have shown above.
Yes. Two different frames. Two different times. No problem.

This is impossible.
Why is it impossible? Because it offends your common sense? The universe doesn't care about your common sense.

This is a pattern with you. You come here claiming that you've discovered an internal inconsistency or flaw in relativity, and it always turns out that you've made a mistake in applying the theory, or that you simply don't accept what the theory is telling you.

It's fine if you don't want to believe in relativity. But don't pretend that you've found some kind of flaw in it, because you clearly haven't. And, regardless of what you choose to believe, the universe will go right on being relativistic, with or without you. Special relativity is tested literally every day in countless applications. In 100+ years, nobody has ever found a flaw in it. In fact, it's impossible that there is a flaw in the mathematical formulation, since all the results follow from just two (or even one) postulate. If some mathematician or physicist had made a mistake in deriving the basic consequences of the theory, don't you think it would have been found by somebody qualified, in the past 100+ years?

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What's impossible about it?
So you think it's possible for me to see you and yet at the same time you can't see me because you are located somewhere else? Are you sane?
You have two different observers. One sees T1 and N2 align before T2 and N1; the other sees T2 and N1 align before T1 and N2. They do not agree that the two alignments happen in the same time order.
I agree. That is what the diagram shows. How does that resolve the paradox?

So you think it's possible for me to see you and yet at the same time you can't see me because you are located somewhere else?
Is that remotely like anything I wrote above - several times, with careful attention to detail? No, it is not.

Did I not, in fact, say the exact opposite, and explicitly agree with you that it is not possible that N1 and T2 are aligned (or N2 and T1 are aligned) and the observers at those locations not see each other? Read it back and you will find that I agreed with you.

Didn't you read my posts? Are you sane? Don't waste my time.

I agree. That is what the diagram shows. How does that resolve the paradox?
What paradox? There's no paradox.

By now, Zeno, after a decade or more to digest the basics of relativity, you should be aware that different observers do not have to agree on where or when events occur in spacetime. They only have to agree on what happens. Any event that occurs, must occur for all observers. But the spacetime coordinates that different observers assign to a particular spacetime event can differ.

It's not rocket science*. Nobody should need to spend more than a decade struggling to understand the basic concepts of relativity.

Give it up. You're just not cut out for this stuff.

---
* Well, okay, maybe it is rocket science, just a bit.

Zeno: I have a clarifying question for you: Do you want to learn how relativity of simultaneity actually works, or do you want to stay stuck in not understanding it?

Perhaps the question that should be asked of Zeno, is that most certainly he has an agenda of sorts, probably religious. I mean that since science has pushed any need for any IDer back to at least t+10-43 seconds, that would obviously infuriate the more religious fanatics, and so obviously they would see it there duty to claim that one of the greatest realizations in the world, is that it is relativistic and that this is shown to be factual everyday, and continually taken into account with scientific experiments is false or somehow invalid.
I remember another that pushed this line, chinglu or something like that.

Zeno: I have a clarifying question for you: Do you want to learn how relativity of simultaneity actually works, or do you want to stay stuck in not understanding it?
Rhetorical?

Zeno: I have a clarifying question for you: Do you want to learn how relativity of simultaneity actually works, or do you want to stay stuck in not understanding it?

I want to understand it better than perhaps I do .

Simultaneous is about the speed of light .

Rhetorical?
Well, no. I am sincerely asking if he's happy with his ideas, or whether he is merely struggling to break out of his own thought processes.

Let me try to make this more clear...
Ship1 at rest on top
Code:
``````       T-----------------------N
<----- N----------T``````

Ship2 at rest at bottom.
Code:
``````T-------N  ------->
N--------------------T``````

Since T1 and N2 are lined up and the observers can see each other this must be the same moment for both ship1 and ship2. Does everyone agree with this? If you do then let's go back a little bit in time....

Ship1 at rest on top
Code:
``````T-------------------------N
<----- N----------T``````

Ship2 at rest at bottom.
Code:
``````T------N ----->
N---------------------T``````

So the observer at N1 can see the observer at T2 and yet the observer at T2 can't see the observer at N1.
There is obviously a problem here because it is an impossible situation.

Let me try to make this more clear...
Ship1 at rest on top
Code:
``````       T-----------------------N
<----- N----------T``````

Ship2 at rest at bottom.
Code:
``````T-------N  ------->
N--------------------T``````

Since T1 and N2 are lined up and the observers can see each other this must be the same moment for both ship1 and ship2. Does everyone agree with this? If you do then let's go back a little bit in time....

Ship1 at rest on top
Code:
``````T-------------------------N
<----- N----------T``````

Ship2 at rest at bottom.
Code:
``````T------N ----->
N---------------------T``````

So the observer at N1 can see the observer at T2 and yet the observer at T2 can't see the observer at N1.
There is obviously a problem here because it is an impossible situation.

Then what has observer N1 have that observer T2 doesn't ?

Technology of detection .