Groups > sci.physics.relativity > #408232

Re: twin paradox with distant mirror

From	Odd Bodkin <bodkinodd@gmail.com>
Newsgroups	sci.physics.relativity
Subject	Re: twin paradox with distant mirror
Date	2017-02-07 08:21 -0600
Organization	Aioe.org NNTP Server
Message-ID	<o7cl57$1rhj$2@gioia.aioe.org> (permalink)
References	(1 earlier) <o7ccjm$pov$1@news.albasani.net> <656a8583-49e6-442c-a336-2341ba93975d@googlegroups.com> <3b6438bb-1934-4bf2-b04d-226f53a2fc57@googlegroups.com> <88ddab8e-7260-4740-b2a0-3cc6c63ba312@googlegroups.com> <e24c274a-d640-4535-9018-0efe9b5c23ee@googlegroups.com>

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On 2/7/2017 8:00 AM, gertjacobusse@gmail.com wrote:
>> In B's frame of reference the distance is length contracted, this is why.
>
> Thank you, the fast and competent responses are really helpful, I think I understand a bit more
> now (although it is not parsimonious for me and my naive space/time perception to alter both
> space and time to maintain a constant c). I think I need to dive into the equations of Pauls
> links to understand more details.
>
> For me at least one question remains: is this twin paradox thought experiment even theoretically
> possible? B needs to change from his outgoing frame (speed 0.99c relative to A) to an incoming
> frame (speed -0.99c relative to A). Relative to his own inertial frame, B would need to change
> his speed 2*0.99*c (faster than light) in the direction of A. Isn't that impossible?
>

The change in VELOCITY is 2*0.99*c, not the change in speed. Speed and 
velocity are distinct in physics. Speed is the magnitude of the 
velocity, sign removed. The change in velocity accounts also for change 
in direction (here sign).

I assure you, there's nothing forbidden about a change in velocity of 
2*0.99*c.

-- 
Odd Bodkin -- maker of fine toys, tools, tables

Thread

twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-06 11:55 -0800
  Re: twin paradox with distant mirror Ned Latham <nedlatham@woden.valhalla.oz> - 2017-02-06 22:33 +0000
  Re: twin paradox with distant mirror "Dono," <sa_ge@comcast.net> - 2017-02-06 15:11 -0800
    Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-06 23:44 -0800
      Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-07 02:46 -0800
      Re: twin paradox with distant mirror "Paul B. Andersen" <relativity@paulba.no> - 2017-02-07 16:29 +0100
  Re: twin paradox with distant mirror rotchm <rotchm@gmail.com> - 2017-02-06 21:40 -0800
    Re: twin paradox with distant mirror "Dono," <sa_ge@comcast.net> - 2017-02-06 22:27 -0800
  Re: twin paradox with distant mirror "Paul B. Andersen" <relativity@paulba.no> - 2017-02-07 12:55 +0100
    Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-07 04:51 -0800
      Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-07 05:33 -0800
        Re: twin paradox with distant mirror "Dono," <sa_ge@comcast.net> - 2017-02-07 05:45 -0800
          Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-07 06:00 -0800
            Re: twin paradox with distant mirror "Dono," <sa_ge@comcast.net> - 2017-02-07 06:17 -0800
            Re: twin paradox with distant mirror Odd Bodkin <bodkinodd@gmail.com> - 2017-02-07 08:21 -0600
              Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-07 06:51 -0800
                Re: twin paradox with distant mirror "Dono," <sa_ge@comcast.net> - 2017-02-07 07:09 -0800
              Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-08 06:23 -0800
                Re: twin paradox with distant mirror mlwozniak@wp.pl - 2017-02-08 06:51 -0800
                Re: twin paradox with distant mirror gertjacobusse@gmail.com - 2017-02-08 13:30 -0800
                Re: twin paradox with distant mirror mlwozniak@wp.pl - 2017-02-08 22:49 -0800

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