ISF Logo   IS Forum
Forum Index Register Members List Events Mark Forums Read Help

Go Back   International Skeptics Forum » General Topics » Science, Mathematics, Medicine, and Technology
 


Welcome to the International Skeptics Forum, where we discuss skepticism, critical thinking, the paranormal and science in a friendly but lively way. You are currently viewing the forum as a guest, which means you are missing out on discussing matters that are of interest to you. Please consider registering so you can gain full use of the forum features and interact with other Members. Registration is simple, fast and free! Click here to register today.
Reply
Old 21st August 2020, 12:57 PM   #321
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Ziggurat View Post
No it doesn't. What made you think it does?
This diagram shows how traveling comoving observer crosses 3.4641cs'.






Is accelerating traveling twin crossing 3.4641cs'? Yes.
Why would comoving inertial observer cross different distance?

Last edited by SDG; 21st August 2020 at 01:05 PM.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 01:02 PM   #322
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Pixel42 View Post
You have been given answers in this thread, and in previous ones. Your errors have been explained to you as simply as they can be explained. That you still do not understand how relativity works is your problem, and yours alone. Nobody here is under any obligation to educate you.
Your post is off topic as well.
Nobody makes you read this thread.
Please, do not post if you are not interested to discuss the topic.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 01:21 PM   #323
Pixel42
Schr÷dinger's cat
 
Pixel42's Avatar
 
Join Date: May 2004
Location: Malmesbury, UK
Posts: 12,694
Originally Posted by SDG View Post
Your post is off topic as well.
Nobody makes you read this thread.
Please, do not post if you are not interested to discuss the topic.
I'm mildly interested in why people post questions and then make no attempt to understand the answers. That seems to be the topic of this thread, so I will continue to read (and occasionally comment on) it.
__________________
"If you trust in yourself ... and believe in your dreams ... and follow your star ... you'll still get beaten by people who spent their time working hard and learning things" - Terry Pratchett
Pixel42 is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 01:22 PM   #324
Myriad
The Clarity Is Devastating
 
Myriad's Avatar
 
Join Date: Nov 2006
Location: Betwixt
Posts: 17,055
Originally Posted by SDG View Post
This diagram shows how traveling comoving observer crosses 3.4641cs'.[/url]

If the overlapping blacked dashed lines are supposed to represent the trajectory of the "comoving observer," why does the line not cross event A? In your other diagram (from page 51) the comoving observer's blue world line crosses event A. Why the discrepancy? Which diagram is supposed to depict the comoving observer?

There are three pairs of coordinates labeled in the diagram in the quoted post, which do not appear to represent correct coordinates on either of the sets of axes in the diagram, given that event A occurs at the origin.

I conclude that nothing of interest can be "shown" by this erroneous diagram that is neither self-consistent nor actually represents the scenario described.
__________________
A z°mbie once bit my sister...
Myriad is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 01:34 PM   #325
HansMustermann
Penultimate Amazing
 
Join Date: Mar 2009
Posts: 17,246
Originally Posted by SDG View Post
This is the view of comoving inertial observer with the traveling twin.
When it comes to acceleration, the view, i.e., what it looks like, doesn't matter at all.

E.g., let's say we have one twin just floating around somewhere in the Bo÷tes void, i.e., in space as flat as physically possible, and the other one firing his thrusters to go 10g in the other direction. Sure, from the view of both of them, it's the other one that is accelerating away. But only one of the frames (well, chart) is actually non-inertial. Only one of them actually has to apply GR corrections. Only one of them sees an event horizon behind him.

And although it's not GR, the same applies to the twin "paradox". Each of them might "view" the other as going 5 light year away and then coming back, but only one of them actually switches between two different frames. The other is sitting in a single inertial frame the whole time.

So basically sometimes things are not what they look like. (Like, there was this time when the sign on the door said "women", but inside there was only a public toilet )
__________________
Which part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn" don't you understand?

Last edited by HansMustermann; 21st August 2020 at 01:35 PM.
HansMustermann is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 02:02 PM   #326
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by HansMustermann View Post
When it comes to acceleration, the view, i.e., what it looks like, doesn't matter at all.

E.g., let's say we have one twin just floating around somewhere in the Bo÷tes void, i.e., in space as flat as physically possible, and the other one firing his thrusters to go 10g in the other direction. Sure, from the view of both of them, it's the other one that is accelerating away. But only one of the frames (well, chart) is actually non-inertial. Only one of them actually has to apply GR corrections. Only one of them sees an event horizon behind him.

And although it's not GR, the same applies to the twin "paradox". Each of them might "view" the other as going 5 light year away and then coming back, but only one of them actually switches between two different frames. The other is sitting in a single inertial frame the whole time.

So basically sometimes things are not what they look like. (Like, there was this time when the sign on the door said "women", but inside there was only a public toilet )
The twin paradox needs a roundtrip.
The roundtrip can be done in a curved trajectory or it can be done linear way (away, stop, coming back).
These are different scenarios.
In order to do a linear roundtrip it makes sense to analyze away trip first.
The last posts were aimed at the acceleration/deceleration and stopping at a distance.
This is a first leg of the linear twin paradox.
It is supposed to be simple but we cannot agree on the distance crossed and time it takes.
It is tricky like that sign you mentioned.

Last edited by SDG; 21st August 2020 at 02:03 PM.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 02:08 PM   #327
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Pixel42 View Post
I'm mildly interested in why people post questions and then make no attempt to understand the answers. That seems to be the topic of this thread, so I will continue to read (and occasionally comment on) it.
I see, psychology
How do you know I made no attempt to understand the answers?
What's your take, what distance is crossed?
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 02:30 PM   #328
Robin
Penultimate Amazing
 
Join Date: Apr 2004
Posts: 12,801
Originally Posted by SDG View Post
It is easy to show how to distinguish between linear and rotational acceleration.
Of course, who said otherwise. All the more reason that your equivalence between them is wrong.
__________________
The non-theoretical character of metaphysics would not be in itself a defect; all arts have this non-theoretical character without thereby losing their high value for personal as well as for social life. The danger lies in the deceptive character of metaphysics; it gives the illusion of knowledge without actually giving any knowledge. This is the reason why we reject it. - Rudolf Carnap "Philosophy and Logical Syntax"
Robin is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 02:36 PM   #329
Robin
Penultimate Amazing
 
Join Date: Apr 2004
Posts: 12,801
Originally Posted by SDG View Post
How do we settle the time of the traveling twin that stops?

Is it 4s' or 2s'?

I showed exactly why it is 4s'.
The travelling twin has 2s on his clock. Any clock that remained stationary in the original frame will have 4s on it.
__________________
The non-theoretical character of metaphysics would not be in itself a defect; all arts have this non-theoretical character without thereby losing their high value for personal as well as for social life. The danger lies in the deceptive character of metaphysics; it gives the illusion of knowledge without actually giving any knowledge. This is the reason why we reject it. - Rudolf Carnap "Philosophy and Logical Syntax"
Robin is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 03:09 PM   #330
Robin
Penultimate Amazing
 
Join Date: Apr 2004
Posts: 12,801
Originally Posted by SDG View Post
How do you know I made no attempt to understand the answers?
Because every time someone says you can't treat a non-inertial frame like an inertial frame you respond by treating a non-inertial frame like an inertial frame.

Whenever someone points out that the limitations of some simplification you are using is not a problem with the underlying theory you respond by treating the limitations of a simplification you are using as a problem for the underlying theory.

So either you have made no attempt to understand the answers or you have and you are simply ignoring them.

Can you point out some problem that is not just a limitation of a simplification you are using or that doesn't stem from trying to treat a non-inertial frame the same way as an inertial frame?
__________________
The non-theoretical character of metaphysics would not be in itself a defect; all arts have this non-theoretical character without thereby losing their high value for personal as well as for social life. The danger lies in the deceptive character of metaphysics; it gives the illusion of knowledge without actually giving any knowledge. This is the reason why we reject it. - Rudolf Carnap "Philosophy and Logical Syntax"
Robin is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 03:14 PM   #331
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Robin View Post
Of course, who said otherwise. All the more reason that your equivalence between them is wrong.
I pointed out the relationship between gravitational and rotational acceleration.
The idea is that gravitational acceleration cannot be distinguished from the linear acceleration in flat spacetime.

They are very much alike and it is Einstein who came with the EP, assuming an unrealistic uniform gravitational acceleration.
Another EP version calls for 'local' effects of motion. What local is good enough local?
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 03:38 PM   #332
Roger Ramjets
Philosopher
 
Roger Ramjets's Avatar
 
Join Date: Jun 2008
Posts: 5,159
Originally Posted by SDG View Post
and it is Einstein who came with the EP, assuming an unrealistic uniform gravitational acceleration.
Einstein was 'unrealistic' but you can't even get your terms right. What exactly are you trying to prove?
__________________
We don't want good, sound arguments. We want arguments that sound good.
Roger Ramjets is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 03:39 PM   #333
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Robin View Post
Because every time someone says you can't treat a non-inertial frame like an inertial frame you respond by treating a non-inertial frame like an inertial frame.

Whenever someone points out that the limitations of some simplification you are using is not a problem with the underlying theory you respond by treating the limitations of a simplification you are using as a problem for the underlying theory.

So either you have made no attempt to understand the answers or you have and you are simply ignoring them.

Can you point out some problem that is not just a limitation of a simplification you are using or that doesn't stem from trying to treat a non-inertial frame the same way as an inertial frame?


Have you ever heard about momentarily comoving inertial reference frames?













That's the X/R idea that was already discussed in this thread as well.
Going back to this diagram because I am asked to be precise.




There is the dashed world line - real life acceleration.
There is the red line representing the accelerated observer with the X/R calculation.
The blue line is for the inertial observer.
The question, does the blue inertial observer crosses the same distance as the accelerated traveling twin?
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 03:42 PM   #334
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Roger Ramjets View Post
Einstein was 'unrealistic' but you can't even get your terms right. What exactly are you trying to prove?

Where we can find parallel gravitational acceleration lines of a meaningful magnitude in the universe?
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 03:49 PM   #335
HansMustermann
Penultimate Amazing
 
Join Date: Mar 2009
Posts: 17,246
Originally Posted by SDG View Post
The twin paradox needs a roundtrip.
The roundtrip can be done in a curved trajectory or it can be done linear way (away, stop, coming back).
These are different scenarios.
In order to do a linear roundtrip it makes sense to analyze away trip first.
The last posts were aimed at the acceleration/deceleration and stopping at a distance.
This is a first leg of the linear twin paradox.
It is supposed to be simple but we cannot agree on the distance crossed and time it takes.
It is tricky like that sign you mentioned.
Well, now you've modified the problem, but you still have one of the twins switching between two frames: moving and stopped. Meanwhile the other frame still is only one frame, and inertial at that. Things are still not exactly symmetrical, no matter how they might LOOK from each other's perspective.

But even that's not important for why things aren't going to be symmetrical, because it's even simpler than that.

Let's put it like this: let's say the moving guy goes all the way to Ross 128, which I'm choosing just because it's almost exactly 11 light years away. It makes the maths easier if I don't have to worry about a lot of decimals. Let's also pretend that Earth is an inertial reference frame, which it isn't, but it's close enough for government work. And that Ross 128 is at a fixed position in it, which again it isn't really, but close enough.

And I'll even go with your 0.866c speed. A gamma value of 2 is easy enough for maths.

Agreed so far?

In which frame did we measure that 11 light year distance? Well, in Earth's frame, innit?

Now remember that 20m ship and 10m hangar example I used on the first page? Like how the guy in the hangar saw the distance measured in the ship's frame (like the ship size), compressed to half, BUT, and this is the important part, the guy on the ship also saw the same thing about distances measured in the hangar's frame (like the hangar length) also compressed by the same factor?

Well, now we essentially have the same problem in a 11 ly long "hangar". One end of the "hangar" is on Earth, the other end of the hangar is at Ross 128. But otherwise it's the same problem.

Like in the hangar example, the guy sitting back on Earth is not just seeing a different speed on the clock of the guy in the rocket. He also sees the rocket squashed to half length.

Like in the hangar example, the guy in the rocket doesn't just see a different clock speed on Earth. He also sees the "hangar" length squashed to half. Except in this case the "hangar" length is the distance between Earth and Ross 128. When he starts going at 0.866c, he sees Ross 128 coming at him at 0.866c, BUT, and this is the important part, from only 5.5 light years away.

So now let's look at what each twin sees:

- For the guy on Earth, in whose frame that 11 ly distance to Ross 128 was measured, he sees the rocket moving at 0.866c for the whole 11 ly distance. So it will take t=l/v=11/0.866=12.9 years to get there. (Rounded to one decimal.)

- For the guy in the rocket, the distance to Ross 128 is only 5.5 light years. And Ross 128 is coming at him at 0.866c. And it will reach him in t=l/v=5.5/0.866=6.4 years. (Again, rounded to the same precision.)

The two won't have the same time on their clocks. There is no symmetry.

Basically the key to understanding it is to understand that the Lorentz transform doesn't only apply to TIME. It also applies to DISTANCE.

Yes, they do see each other's TIME modified by the same gamma factor. But the same applies to the DISTANCE. It won't be the same distance in the two frames. Any distance you pick will be measured in one or the other, and needs a Lorentz transform before you know it in the other one.
__________________
Which part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn" don't you understand?

Last edited by HansMustermann; 21st August 2020 at 04:12 PM.
HansMustermann is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 04:11 PM   #336
Robin
Penultimate Amazing
 
Join Date: Apr 2004
Posts: 12,801
Originally Posted by SDG View Post
Have you ever heard about momentarily comoving inertial reference frames?
Yes, of course. We had a long discussion about them in another thread, don't you remember?




Quote:
Going back to this diagram because I am asked to be precise.



https://i.imgur.com/xIVUcQT.png





There is the dashed world line - real life acceleration.

There is the red line representing the accelerated observer with the X/R calculation.

The blue line is for the inertial observer.

The question, does the blue inertial observer crosses the same distance as the accelerated traveling twin?
So let's say that if they both sent a light signal at t=x=0 and someone had recorded its arrival then the signal would have reached their destination at the same time.

On the other hand it might be the case that at T/8 the accelerated traveller might agree with another inertial traveller using this method that the distance to the same point is less than three quarters of the distance he had agreed with the first inertial traveller.

Or to put it another way, from the viewpoint of the inertial traveller, the accelerated traveller would have moved to the left, then swung round to the right and then come back to where he is. So he wouldn't think that someone who had moved would have covered the same distance as someone who had stayed still.
__________________
The non-theoretical character of metaphysics would not be in itself a defect; all arts have this non-theoretical character without thereby losing their high value for personal as well as for social life. The danger lies in the deceptive character of metaphysics; it gives the illusion of knowledge without actually giving any knowledge. This is the reason why we reject it. - Rudolf Carnap "Philosophy and Logical Syntax"

Last edited by Robin; 21st August 2020 at 06:00 PM.
Robin is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 10:15 PM   #337
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by HansMustermann View Post
Well, now you've modified the problem, but you still have one of the twins switching between two frames: moving and stopped. Meanwhile the other frame still is only one frame, and inertial at that. Things are still not exactly symmetrical, no matter how they might LOOK from each other's perspective.

But even that's not important for why things aren't going to be symmetrical, because it's even simpler than that.

Let's put it like this: let's say the moving guy goes all the way to Ross 128, which I'm choosing just because it's almost exactly 11 light years away. It makes the maths easier if I don't have to worry about a lot of decimals. Let's also pretend that Earth is an inertial reference frame, which it isn't, but it's close enough for government work. And that Ross 128 is at a fixed position in it, which again it isn't really, but close enough.

And I'll even go with your 0.866c speed. A gamma value of 2 is easy enough for maths.

Agreed so far?

In which frame did we measure that 11 light year distance? Well, in Earth's frame, innit?

Now remember that 20m ship and 10m hangar example I used on the first page? Like how the guy in the hangar saw the distance measured in the ship's frame (like the ship size), compressed to half, BUT, and this is the important part, the guy on the ship also saw the same thing about distances measured in the hangar's frame (like the hangar length) also compressed by the same factor?

Well, now we essentially have the same problem in a 11 ly long "hangar". One end of the "hangar" is on Earth, the other end of the hangar is at Ross 128. But otherwise it's the same problem.

Like in the hangar example, the guy sitting back on Earth is not just seeing a different speed on the clock of the guy in the rocket. He also sees the rocket squashed to half length.

Like in the hangar example, the guy in the rocket doesn't just see a different clock speed on Earth. He also sees the "hangar" length squashed to half. Except in this case the "hangar" length is the distance between Earth and Ross 128. When he starts going at 0.866c, he sees Ross 128 coming at him at 0.866c, BUT, and this is the important part, from only 5.5 light years away.

So now let's look at what each twin sees:

- For the guy on Earth, in whose frame that 11 ly distance to Ross 128 was measured, he sees the rocket moving at 0.866c for the whole 11 ly distance. So it will take t=l/v=11/0.866=12.9 years to get there. (Rounded to one decimal.)

- For the guy in the rocket, the distance to Ross 128 is only 5.5 light years. And Ross 128 is coming at him at 0.866c. And it will reach him in t=l/v=5.5/0.866=6.4 years. (Again, rounded to the same precision.)

The two won't have the same time on their clocks. There is no symmetry.

Basically the key to understanding it is to understand that the Lorentz transform doesn't only apply to TIME. It also applies to DISTANCE.

Yes, they do see each other's TIME modified by the same gamma factor. But the same applies to the DISTANCE. It won't be the same distance in the two frames. Any distance you pick will be measured in one or the other, and needs a Lorentz transform before you know it in the other one.
The Lorentz contraction is the consequence of the relativity of simultaneity.
It is not physical space contraction between the stars.
If the stars are inertial, no relative motion between them, they are in the same inertial reference frame then the distance L0 is defined by how long it takes for the light to cross the distance between them.
If it is 11 light years then it is 11 light years.
The traveler has to cross 11 light years because the traveler starts and stops in the same frame.
The simultaneity line is the horizontal line in the beginning and at the end.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 10:33 PM   #338
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Robin View Post
Yes, of course. We had a long discussion about them in another thread, don't you remember?





So let's say that if they both sent a light signal at t=x=0 and someone had recorded its arrival then the signal would have reached their destination at the same time.

On the other hand it might be the case that at T/8 the accelerated traveller might agree with another inertial traveller using this method that the distance to the same point is less than three quarters of the distance he had agreed with the first inertial traveller.

Or to put it another way, from the viewpoint of the inertial traveller, the accelerated traveller would have moved to the left, then swung round to the right and then come back to where he is. So he wouldn't think that someone who had moved would have covered the same distance as someone who had stayed still.


Here is another point of view, very extreme one but it might be useful.
Do you remember the X/R analysis.
How long for the front to cross the distance? Let's say 2s'.
But when the front is moving across the back stays back, that's the extreme 10100 X/R ratio analysis.
The acceleration is causing the front clock de-synchronize with the back clock.
The front clock 2s' and the back clock 0s' in the meantime. Not exact 0s' but very close to it.
How long for the back to catch the front? Another 2s'.
The back 2s' and the front 0s' in the meantime.
The total is 4s'.




The front is opening coming up first then the back is catching up.
That's the extreme X/R analysis.
We cannot say that the front and the back are accelerating in parallel because that would not allow for the de-synchronization between the front an the back clocks.
The clock de-synchronization between the back and the front is the reason the result cannot be 2s'.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 10:50 PM   #339
Robin
Penultimate Amazing
 
Join Date: Apr 2004
Posts: 12,801
If you are saying that relativity is weird or counter intuitive then I doubt you will get many arguments.

But it is mathematically consistent and experimentally verified, which is the important thing.
__________________
The non-theoretical character of metaphysics would not be in itself a defect; all arts have this non-theoretical character without thereby losing their high value for personal as well as for social life. The danger lies in the deceptive character of metaphysics; it gives the illusion of knowledge without actually giving any knowledge. This is the reason why we reject it. - Rudolf Carnap "Philosophy and Logical Syntax"
Robin is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 11:03 PM   #340
Robin
Penultimate Amazing
 
Join Date: Apr 2004
Posts: 12,801
Originally Posted by SDG View Post
Here is another point of view, very extreme one but it might be useful.

Do you remember the X/R analysis.

How long for the front to cross the distance? Let's say 2s'.

But when the front is moving across the back stays back, that's the extreme 10100 X/R ratio analysis.

The acceleration is causing the front clock de-synchronize with the back clock.

The front clock 2s' and the back clock 0s' in the meantime. Not exact 0s' but very close to it.

How long for the back to catch the front? Another 2s'.

The back 2s' and the front 0s' in the meantime.

The total is 4s'.





https://i.imgur.com/3TyzBkF.png



The front is opening coming up first then the back is catching up.

That's the extreme X/R analysis.

We cannot say that the front and the back are accelerating in parallel because that would not allow for the de-synchronization between the front an the back clocks.

The clock de-synchronization between the back and the front is the reason the result cannot be 2s'.
How long is it from the front to the back?
__________________
The non-theoretical character of metaphysics would not be in itself a defect; all arts have this non-theoretical character without thereby losing their high value for personal as well as for social life. The danger lies in the deceptive character of metaphysics; it gives the illusion of knowledge without actually giving any knowledge. This is the reason why we reject it. - Rudolf Carnap "Philosophy and Logical Syntax"
Robin is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 11:23 PM   #341
Roger Ramjets
Philosopher
 
Roger Ramjets's Avatar
 
Join Date: Jun 2008
Posts: 5,159
Originally Posted by SDG View Post
Where we can find parallel gravitational acceleration lines of a meaningful magnitude in the universe?
What are 'gravitational acceleration lines' and how can they have a magnitude? What will they look like if we find them?
__________________
We don't want good, sound arguments. We want arguments that sound good.
Roger Ramjets is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 21st August 2020, 11:29 PM   #342
Pixel42
Schr÷dinger's cat
 
Pixel42's Avatar
 
Join Date: May 2004
Location: Malmesbury, UK
Posts: 12,694
Originally Posted by SDG View Post
I see, psychology
How do you know I made no attempt to understand the answers?
By reading your posts in this and previous threads.

Quote:
What's your take, what distance is crossed?
I've wasted all the time I'm going to waste trying to educate someone who refuses to learn.
__________________
"If you trust in yourself ... and believe in your dreams ... and follow your star ... you'll still get beaten by people who spent their time working hard and learning things" - Terry Pratchett
Pixel42 is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 12:40 AM   #343
HansMustermann
Penultimate Amazing
 
Join Date: Mar 2009
Posts: 17,246
Originally Posted by SDG View Post
The Lorentz contraction is the consequence of the relativity of simultaneity.
It is not physical space contraction between the stars.
If the stars are inertial, no relative motion between them, they are in the same inertial reference frame then the distance L0 is defined by how long it takes for the light to cross the distance between them.
If it is 11 light years then it is 11 light years.
The traveler has to cross 11 light years because the traveler starts and stops in the same frame.
The simultaneity line is the horizontal line in the beginning and at the end.
The question isn't whether there's any motion between them. The question is in which frame you measure it. There also isn't any motion between the tip and tail of the rocket, yet in the frame of the guy back on Earth, that distance is shorter.

And in what frame you start or stop is irrelevant. The moment you started or stopped, you changed frames. What is the case in that frame is not the same as in the frame when you were moving. Neither when it comes to measured distances, nor when it comes to simultaneity. In fact, the fact that the same distance is measured differently is, in fact, having to do with the fact that events which are simultaneous in one frame are not in another. That also includes the frame when you were stopped and the frame when you were moving.

I.e., what you wrote above is just about the dumbest thing ever, if you presume to lecture about how relativity works.
__________________
Which part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn" don't you understand?

Last edited by HansMustermann; 22nd August 2020 at 02:39 AM.
HansMustermann is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 01:06 AM   #344
Darat
Lackey
Administrator
 
Darat's Avatar
 
Join Date: Aug 2001
Location: South East, UK
Posts: 94,843
Originally Posted by SDG View Post
I posted questions.

Do you have some answers?

It is not important what I think in regards to your question.

Your question is off topic.

I am not going to discuss that.
SDG - do you really think you have spotted something that literally generations of physicists and mathematicians have got wrong?
__________________
I wish I knew how to quit you
Darat is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 01:07 AM   #345
Darat
Lackey
Administrator
 
Darat's Avatar
 
Join Date: Aug 2001
Location: South East, UK
Posts: 94,843
Originally Posted by SDG View Post
Your post is off topic as well.

Nobody makes you read this thread.

Please, do not post if you are not interested to discuss the topic.
SDG - do you really think you have spotted something that literally generations of physicists and mathematicians have got wrong?
__________________
I wish I knew how to quit you
Darat is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 07:51 AM   #346
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Robin View Post
How long is it from the front to the back?
The L0=3.4641cs'
That's the 6.9282cs in the left moving platform frame when simultaneity is at work.

SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 07:54 AM   #347
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Roger Ramjets View Post
What are 'gravitational acceleration lines' and how can they have a magnitude? What will they look like if we find them?
What can I say, google is your friend.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 07:55 AM   #348
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Pixel42 View Post
By reading your posts in this and previous threads.


I've wasted all the time I'm going to waste trying to educate someone who refuses to learn.
Yet, you are still reading this thread.
I guess it must be entertaining.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 08:09 AM   #349
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by HansMustermann View Post
The question isn't whether there's any motion between them. The question is in which frame you measure it. There also isn't any motion between the tip and tail of the rocket, yet in the frame of the guy back on Earth, that distance is shorter.

And in what frame you start or stop is irrelevant. The moment you started or stopped, you changed frames. What is the case in that frame is not the same as in the frame when you were moving. Neither when it comes to measured distances, nor when it comes to simultaneity. In fact, the fact that the same distance is measured differently is, in fact, having to do with the fact that events which are simultaneous in one frame are not in another. That also includes the frame when you were stopped and the frame when you were moving.

I.e., what you wrote above is just about the dumbest thing ever, if you presume to lecture about how relativity works.

It is not dumb what I wrote.
Look, the simultaneity is a problem for the measurement.
The rest frame length L0 is what all observers are supposed to agree upon.

Having said that the distance between the tip and the tail of the rocket is not agreed upon during acceleration.
That's what relativity physicists do not agree upon.
There are some that say the length contraction is real, physical and there are others who say it is not real.


Bell's spaceship paradox #Importance_of_length_contraction


Quote:
In general, it was concluded by Dewan & Beran and Bell, that relativistic stresses arise when all parts of an object are accelerated the same way with respect to an inertial frame, and that length contraction has real physical consequences. For instance, Bell argued that the length contraction of objects as well as the lack of length contraction between objects in frame S can be explained using relativistic electromagnetism. The distorted electromagnetic intermolecular fields cause moving objects to contract, or to become stressed if hindered from doing so. In contrast, no such forces act on the space between objects.

Quote:
However, they denied the idea that those stresses are caused by length contraction in S. This is because, in their opinion, length contraction has no "physical reality", but is merely the result of a Lorentz transformation, i.e. a rotation in four-dimensional space which by itself can never cause any stress at all.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 08:14 AM   #350
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Robin View Post
If you are saying that relativity is weird or counter intuitive then I doubt you will get many arguments.

But it is mathematically consistent and experimentally verified, which is the important thing.
The consequence of the mathematical consistency is the reciprocity of the Special Relativity.
It is consistent in creating the paradoxes.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 08:16 AM   #351
Robin
Penultimate Amazing
 
Join Date: Apr 2004
Posts: 12,801
Originally Posted by SDG View Post
The L0=3.4641cs'

That's the 6.9282cs in the left moving platform frame when simultaneity is at work.



https://i.imgur.com/CYocBbl.png
That is just lots of lines on a diagram with no explanation of what they are supposed to represent.
__________________
The non-theoretical character of metaphysics would not be in itself a defect; all arts have this non-theoretical character without thereby losing their high value for personal as well as for social life. The danger lies in the deceptive character of metaphysics; it gives the illusion of knowledge without actually giving any knowledge. This is the reason why we reject it. - Rudolf Carnap "Philosophy and Logical Syntax"
Robin is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 08:37 AM   #352
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Robin View Post
That is just lots of lines on a diagram with no explanation of what they are supposed to represent.
It goes back to post #301, more details in that post.
The black horizontal lines are 3.4641cs' length of the platform ruler in the ct', x' traveling twin frame.
The ruler is crossing 3.4641cs' distance.
The ct, x frame is the platform frame that moves to the left in the train frame.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 10:05 AM   #353
steenkh
Philosopher
 
steenkh's Avatar
 
Join Date: Aug 2002
Location: Denmark
Posts: 6,070
Originally Posted by SDG View Post
Yet, you are still reading this thread.
I guess it must be entertaining.

I too am reading this thread, and for much the same reason: it is fascinating that the same stuff can be explained over and over again, but not having any impact on you.

And it is also fascinating to imagine why you think - in light of the reception here - that you are on to something big that the greatest minds in the past hundred years did not stumble on.
__________________
Steen

--
Jack of all trades - master of none!
steenkh is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 10:41 AM   #354
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by steenkh View Post
I too am reading this thread, and for much the same reason: it is fascinating that the same stuff can be explained over and over again, but not having any impact on you.

And it is also fascinating to imagine why you think - in light of the reception here - that you are on to something big that the greatest minds in the past hundred years did not stumble on.


For starters, is the Lorentz contraction real or not? What do you think?

What is your take on the question if the traveling twin is going to cross 3.4641cs' in 2s' or 4s'? Why faster than light?
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 12:20 PM   #355
KAJ
Student
 
Join Date: Dec 2017
Location: United Kingdom
Posts: 33
Originally Posted by Roger Ramjets View Post
What are 'gravitational acceleration lines' and how can they have a magnitude? What will they look like if we find them?
Originally Posted by SDG View Post
What can I say, google is your friend.
I just Googled "gravitational acceleration lines" and it gave me "It looks like there aren't any great matches for your search".

Can you (SDG) answer the questions?
KAJ is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 12:21 PM   #356
Darat
Lackey
Administrator
 
Darat's Avatar
 
Join Date: Aug 2001
Location: South East, UK
Posts: 94,843
Originally Posted by SDG View Post


For starters, is the Lorentz contraction real or not? What do you think?

What is your take on the question if the traveling twin is going to cross 3.4641cs' in 2s' or 4s'? Why faster than light?
Why do you think you have spotted a mistake that has gone unnoticed by generations of physicists and mathematicians? Why do you think you are not able to convince anyone of your correction to established physics?
__________________
I wish I knew how to quit you
Darat is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 01:23 PM   #357
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by KAJ View Post
I just Googled "gravitational acceleration lines" and it gave me "It looks like there aren't any great matches for your search".

Can you (SDG) answer the questions?
I am to fast in my mind sometimes.
Thinking about the gravitational acceleration in combination with the gravitational field lines and there you have the mix-up.
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 01:45 PM   #358
SDG
Muse
 
Join Date: Jul 2018
Posts: 927
Originally Posted by Darat View Post
Why do you think you have spotted a mistake that has gone unnoticed by generations of physicists and mathematicians? Why do you think you are not able to convince anyone of your correction to established physics?
I asked a specific question and I presented reasons why I asked the question.
Do you have an answer to the question why a traveling twin would cross 3.4641cs' distance in 2s'?
Why the traveling twin would move faster than light?
SDG is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 02:38 PM   #359
KAJ
Student
 
Join Date: Dec 2017
Location: United Kingdom
Posts: 33
Originally Posted by SDG View Post
I am to fast in my mind sometimes.
Thinking about the gravitational acceleration in combination with the gravitational field lines and there you have the mix-up.
So you were wrong when you referred Roger Ramjets to Google for an explanation of gravitational acceleration lines.

Getting back to your question
Originally Posted by SDG View Post
Where we can find parallel gravitational acceleration lines of a meaningful magnitude in the universe?
Roger Ramets asked
Originally Posted by Roger Ramjets View Post
What are 'gravitational acceleration lines' and how can they have a magnitude? What will they look like if we find them?
If you didn't mean "gravitational acceleration lines" what did you mean? Whatever you did mean, can they have a magnitude? What will they look like if we find them?

Or was your question (Where we can find parallel gravitational acceleration lines of a meaningful magnitude in the universe?) meaningless?
KAJ is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Old 22nd August 2020, 02:55 PM   #360
Roger Ramjets
Philosopher
 
Roger Ramjets's Avatar
 
Join Date: Jun 2008
Posts: 5,159
Originally Posted by SDG View Post
What can I say, google is your friend.
Google says 'gravitational acceleration lines' don't exist (and yes, I googled extensively using different words before posting my question - thank you very much for wasting my time!).

You say Einstein was 'unrealistic', but his theories have been verified by experiment - while your 'gravitational acceleration lines' are a fiction.

Quote:
I asked a specific question...
which was answered in post #2.

But that didn't satisfy you. 331 posts later you finally let us in on what you really want to know - or is it???

I think the truth is you just want to show us how smart you are by proving Einstein wrong. Which will never happen. You see, kooks come in here all the time trying to show us how smart they are, and end up looking like idiots. I don't even have to check your math to know that you are almost certainly wrong, because if you knew what you were talking about you wouldn't be arguing about it here - you would be discussing it with actual physicists.
__________________
We don't want good, sound arguments. We want arguments that sound good.
Roger Ramjets is offline   Quote this post in a PM   Nominate this post for this month's language award Copy a direct link to this post Reply With Quote Back to Top
Reply

International Skeptics Forum » General Topics » Science, Mathematics, Medicine, and Technology

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -7. The time now is 01:45 AM.
Powered by vBulletin. Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum began as part of the James Randi Education Foundation (JREF). However, the forum now exists as
an independent entity with no affiliation with or endorsement by the JREF, including the section in reference to "JREF" topics.

Disclaimer: Messages posted in the Forum are solely the opinion of their authors.