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Author Topic:   The Twins Paradox and the speed of light
Bolder-dash
Member (Idle past 977 days)
Posts: 983
From: China
Joined: 11-14-2009


Message 196 of 230 (680180)
11-18-2012 10:21 AM
Reply to: Message 195 by NoNukes
11-18-2012 9:44 AM


Re: Twin paradox space time diagram
Now hold on a minute, are you claiming there would be an age difference between the twins if there was acceleration involved in one of the twins velocity, or if there is no acceleration but just constant velocity or in both cases?

Cavediver is supposed to be an expert in this field, and he can't seem to even answer this in English, so maybe you can.


This message is a reply to:
 Message 195 by NoNukes, posted 11-18-2012 9:44 AM NoNukes has acknowledged this reply

Replies to this message:
 Message 197 by cavediver, posted 11-18-2012 10:33 AM Bolder-dash has responded

  
cavediver
Member (Idle past 990 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 197 of 230 (680182)
11-18-2012 10:33 AM
Reply to: Message 196 by Bolder-dash
11-18-2012 10:21 AM


Re: Twin paradox space time diagram
Cavediver is supposed to be an expert in this field, and he can't seem to even answer this in English, so maybe you can.

I'm sorry, was I pitching my explanations a bit too high for you? Just say the word and I'll dumb it down to your level. Now, you were going to bring me some Einstein quotes, I believe...?


This message is a reply to:
 Message 196 by Bolder-dash, posted 11-18-2012 10:21 AM Bolder-dash has responded

Replies to this message:
 Message 199 by Bolder-dash, posted 11-18-2012 10:51 AM cavediver has responded

  
Bolder-dash
Member (Idle past 977 days)
Posts: 983
From: China
Joined: 11-14-2009


Message 198 of 230 (680183)
11-18-2012 10:48 AM
Reply to: Message 193 by cavediver
11-18-2012 7:27 AM


Re: Twin paradox space time diagram
Well, you can try. Of course, there would by necessity be times when he would be unsure - sure as before he had even entertained Special Relativity, and around the time that the apparent clock paradox (as he termed it) first occured to him. But I'm sure you have something much more concrete than that...

At first you come out saying that it is crap to suggest that Einstein wasn't satisfied with answering this problem, and now you meekly assert that yes, he may have had doubts at times, but that he answered it successfully many times, when in fact you know full well he had doubts about this issue up until his deathbed. I mean come on cavediver, if you call yourself a scientist, why don't you even attempt to discuss in an honest fashion. Einstein repeatedly stated that he wasn't sure that relativity could be applied to real life physical events. In 1921 he said:

"The idea of the measuring rod and the idea of the clock coordinated with it in the theory of relativity do not find their exact correspondence in the real world. It is also clear that the solid body and the clock do not in the conceptual edifice of physics play the part of irreducible elements, but that of composite structures, which may not play any independent part in theoretical physics."

The thing is you know this, of course. And yet you still feel the need to try to win your point by acting like its preposterous to suggest that Einstein wasn't comfortable with an answer to this. Its such a childish position you take, as if all you really care about it trying to appear correct, instead of trying to be truthful. Is your argument so weak, that you feel the need to create false ones. Do you seek to provide honest answers, or are you just here to try to show your manhood? Because its not very authentic or scientific of you. I think you just do it on purpose to be adversarial.


This message is a reply to:
 Message 193 by cavediver, posted 11-18-2012 7:27 AM cavediver has responded

Replies to this message:
 Message 200 by cavediver, posted 11-18-2012 11:05 AM Bolder-dash has responded

  
Bolder-dash
Member (Idle past 977 days)
Posts: 983
From: China
Joined: 11-14-2009


Message 199 of 230 (680185)
11-18-2012 10:51 AM
Reply to: Message 197 by cavediver
11-18-2012 10:33 AM


Re: Twin paradox space time diagram
Then answer the question, will the twins have different ages if one is traveling only at a constant speed, or if one is traveling at an accelerated speed, or in both cases?

Call it A, B, or C, which is it?


This message is a reply to:
 Message 197 by cavediver, posted 11-18-2012 10:33 AM cavediver has responded

Replies to this message:
 Message 202 by cavediver, posted 11-18-2012 11:13 AM Bolder-dash has responded

  
cavediver
Member (Idle past 990 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 200 of 230 (680191)
11-18-2012 11:05 AM
Reply to: Message 198 by Bolder-dash
11-18-2012 10:48 AM


Re: Twin paradox space time diagram
At first you come out saying that it is crap to suggest that Einstein wasn't satisfied with answering this problem, and now you meekly assert that yes, he may have had doubts at times

oh dear, you really need to work on that English comprehension. I was simply and facetiously pointing out that of course Einstein would not have had an answer before the actual question had arisen, and in the minutes before he had managed to actually understand the issue. Do try to keep up.

when in fact you know full well he had doubts about this issue up until his deathbed.

Really? I know full well? Jesus, you must not only be a mind reader but you must be able to see deep into my subconscious mind, because my conscious mind has no such knoweldge and considers the idea that he had such doubts utterly laughable. See? -->

Einstein repeatedly stated that he wasn't sure that relativity could be applied to real life physical events.

No, he did not. Or certainly not that I have seen.

"The idea of the measuring rod and the idea of the clock coordinated with it in the theory of relativity do not find their exact correspondence in the real world. It is also clear that the solid body and the clock do not in the conceptual edifice of physics play the part of irreducible elements, but that of composite structures, which may not play any independent part in theoretical physics."

Are you really so stupid as to think that the above quote suggests that "he wasn't sure that relativity could be applied to real life physical events"? Does it not occur to you, even for the briefest of moments, that Einstein is here talking of the unphysicality of idealised measuring devices? Something that any of us who have actually taught Relativity have stressed ourselves to our students.

Jesus, Bolder-dash, if you are trying to convince us of your utter ineptitude, it is working wonderfully.

blah blah blah

Yep,. Bolder-dash, keep yapping... it is entertaining... for now.

Edited by cavediver, : No reason given.


This message is a reply to:
 Message 198 by Bolder-dash, posted 11-18-2012 10:48 AM Bolder-dash has responded

Replies to this message:
 Message 201 by Bolder-dash, posted 11-18-2012 11:12 AM cavediver has not yet responded

  
Bolder-dash
Member (Idle past 977 days)
Posts: 983
From: China
Joined: 11-14-2009


Message 201 of 230 (680193)
11-18-2012 11:12 AM
Reply to: Message 200 by cavediver
11-18-2012 11:05 AM


Re: Twin paradox space time diagram
A, B, or C cavediver. Its multiple choice. A, B or C?
This message is a reply to:
 Message 200 by cavediver, posted 11-18-2012 11:05 AM cavediver has not yet responded

  
cavediver
Member (Idle past 990 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 202 of 230 (680194)
11-18-2012 11:13 AM
Reply to: Message 199 by Bolder-dash
11-18-2012 10:51 AM


Re: Twin paradox space time diagram
Your question is far too vague. State exactly what you mean. Constant speed does not mean the absence of acceleration; that would be constant velocity. If constant velocity, how are you bringing the two "twins" back into contact?
This message is a reply to:
 Message 199 by Bolder-dash, posted 11-18-2012 10:51 AM Bolder-dash has responded

Replies to this message:
 Message 203 by Bolder-dash, posted 11-18-2012 12:04 PM cavediver has responded
 Message 204 by Bolder-dash, posted 11-18-2012 12:09 PM cavediver has responded

  
Bolder-dash
Member (Idle past 977 days)
Posts: 983
From: China
Joined: 11-14-2009


Message 203 of 230 (680200)
11-18-2012 12:04 PM
Reply to: Message 202 by cavediver
11-18-2012 11:13 AM


Re: Twin paradox space time diagram
Far too vague? Its FAR too vague? Ok, how is this:

I will make them numbers, since you are not as good with letters:

1. The twin who sets out on a journey is at constant velocity, until he reaches his turn around point, he then suddenly stops is accelerated back to the same velocity which is near the speed of light, in approximately one half second, then he continues all the way back at a constant velocity back to the other twin.

2. The twin accelerates the entire time to time a half way point, turns around and accelerates all the way back to the twin at the same speed as in the case of number one, near the speed of light. Always accelerating.

In scenarios 1 or 2, are they the same age, or different ages when they meet up (not counting the half second that he accelerated to near the speed of light in case number 1) ?

3. They each have a clock starting with the same time. One of the twins begins a journey at a constant velocity, near the speed of light, but they never meet again. Do the clocks remain the same from the standpoint of a third party observer with good eyes who always remains exactly half way between the two twins?


This message is a reply to:
 Message 202 by cavediver, posted 11-18-2012 11:13 AM cavediver has responded

Replies to this message:
 Message 206 by cavediver, posted 11-18-2012 1:12 PM Bolder-dash has not yet responded
 Message 209 by NoNukes, posted 11-18-2012 3:44 PM Bolder-dash has not yet responded

  
Bolder-dash
Member (Idle past 977 days)
Posts: 983
From: China
Joined: 11-14-2009


Message 204 of 230 (680201)
11-18-2012 12:09 PM
Reply to: Message 202 by cavediver
11-18-2012 11:13 AM


Re: Twin paradox space time diagram
And here is another option:

1. One of the twins remains on earth, while another twin is accelerated on a giant circle near the speed of light for ten years and ends up back at earth. When he returns are the twins the same age or different? If different who is younger?


This message is a reply to:
 Message 202 by cavediver, posted 11-18-2012 11:13 AM cavediver has responded

Replies to this message:
 Message 207 by cavediver, posted 11-18-2012 1:16 PM Bolder-dash has not yet responded

  
Bolder-dash
Member (Idle past 977 days)
Posts: 983
From: China
Joined: 11-14-2009


Message 205 of 230 (680203)
11-18-2012 12:19 PM


Also I am very curious cavediver. In your initial answer to this question:


They're not. They are simply ticking as normal - but they are being taken on different length paths through space-time. The one that takes the shorter path naturally ticks less, and hence appears younger when the two watches get back together and are compared. The length of a path through space-time equals the time experienced along that path. But space-time is strange - the *longest* (space-time) distance between two points is a straight line!!

Pick two points in space-time: say P1 is Time's Square 00:00:00 1st Jan 2000; and P2 is Time's Square 00:00:00 1st Jul 2008. So sitting still in Time's square in order to get from P1 to P2 is the LONGEST space-time path between these points. Any other path will be shorter! Repeatedly flying back and forth from JFK to Sydney to get from P1 to P2 will be slightly shorter than staying still, so your watch (and your heart) will tick slightly less on this journey - although almost immeasurably less. Travelling out to Alpha Centauri and back at just under the speed of light will just about get you from P1 to P2 and that path will be much much shorter than sitting still, and so your watch will tick considerably less seconds on this path - perhaps only a few days' worth!! So a watch left to sit still between P1 and P2 will tick away 8.5 years, and your watch on your space-trip may only tick away one week!

You don't mention anything about acceleration, do you? Were you intentionally being far too vague? How could you answer this question without knowing if they were accelerating or not?


Replies to this message:
 Message 208 by cavediver, posted 11-18-2012 1:27 PM Bolder-dash has not yet responded

  
cavediver
Member (Idle past 990 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 206 of 230 (680208)
11-18-2012 1:12 PM
Reply to: Message 203 by Bolder-dash
11-18-2012 12:04 PM


Re: Twin paradox space time diagram
1) twin who stays home ages more

2) twin who stays home ages more

3) third party observer in the middle see both clocks running at same rate


This message is a reply to:
 Message 203 by Bolder-dash, posted 11-18-2012 12:04 PM Bolder-dash has not yet responded

  
cavediver
Member (Idle past 990 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 207 of 230 (680209)
11-18-2012 1:16 PM
Reply to: Message 204 by Bolder-dash
11-18-2012 12:09 PM


Re: Twin paradox space time diagram
1) the travelling twin is younger
This message is a reply to:
 Message 204 by Bolder-dash, posted 11-18-2012 12:09 PM Bolder-dash has not yet responded

  
cavediver
Member (Idle past 990 days)
Posts: 4129
From: UK
Joined: 06-16-2005


(1)
Message 208 of 230 (680210)
11-18-2012 1:27 PM
Reply to: Message 205 by Bolder-dash
11-18-2012 12:19 PM


You don't mention anything about acceleration, do you?

No, because it's not really an important point other than when you approach Special Relativity from its limited historical persepctive. To create two different 4d paths through space-time between the same two space-time points, acceleration must be involved with one or both paths. This is a trvial consequence. The important point is the differing path-lengths, not the acceleration.


This message is a reply to:
 Message 205 by Bolder-dash, posted 11-18-2012 12:19 PM Bolder-dash has not yet responded

  
NoNukes
Member
Posts: 9311
From: Central NC USA
Joined: 08-13-2010
Member Rating: 2.7


Message 209 of 230 (680226)
11-18-2012 3:44 PM
Reply to: Message 203 by Bolder-dash
11-18-2012 12:04 PM


Re: Twin paradox space time diagram
Here is a simple way to answer the question plot the distance from the starting point vs time for both travelers on a space time graph. The maximum duration possible is along a horizontal path between events. That is the path traveled by the stay at home twin. Any path deviating from that will show a smaller duration.

1. Path is approximately an isoceles triangle. Duration is less than for stay at home twin. Let's assume that twin is not squished into jelly.

2. Path consists of curved sections rather than straight lines. Duration is less than stay at home twin.

3. Yes. But if we want to ask questions about ages, we will have difficulty specifying a time for a comparison because the participabts will disagree about whether given events are simultaneous.

ABE:

The convention space time graph has time along the vertical axis. I don't think it changes anything other than to say that the maximum duration between two events would be a vertical line which is the path for the stay at home twin.

End of ABE

I will make them numbers, since you are not as good with letters

Uncalled for. It's no big deal not to understand this stuff or to fail to follow the explanations. No need to lash out at people who do understand. Do you truly understand physics well enough so that your intuition that something makes no sense is something to be trusted? I know that such is not the case for me.

You are right about one thing, Einstein did publish a paper in the late 1910s in which he made remarks about the twins paradox that are now known to be incorrect. But what of it? Is there any doubt now that the twin paradox is based on actual and observed physics? If so perhaps we can address your concerns by pointing to experimental evidence.

Edited by NoNukes, : Address unconventional nature of my proposed space-time plot.


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This message is a reply to:
 Message 203 by Bolder-dash, posted 11-18-2012 12:04 PM Bolder-dash has not yet responded

Replies to this message:
 Message 210 by cavediver, posted 11-18-2012 6:46 PM NoNukes has responded

    
cavediver
Member (Idle past 990 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 210 of 230 (680242)
11-18-2012 6:46 PM
Reply to: Message 209 by NoNukes
11-18-2012 3:44 PM


Re: Twin paradox space time diagram
Einstein did publish a paper in the late 1910s in which he made remarks about the twins paradox that are now known to be incorrect.

Can you point me to this, as I haven't come across this before. Admittedly, there was a whole host of arguments and counter-arguments in the SR early days and I have this picture of Minkowski simply banging his head against his desk, saying "please, just look at it my way". Of course, by 1910, he had sadly already died.


This message is a reply to:
 Message 209 by NoNukes, posted 11-18-2012 3:44 PM NoNukes has responded

Replies to this message:
 Message 211 by NoNukes, posted 11-18-2012 8:30 PM cavediver has responded

  
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