X-Message-Number: 16318
Date: Thu, 24 May 2001 13:10:22 +1000
From: Damien Broderick <>
Subject: re: Time travel and cryonics

>From: "George Smith" <>
>References: <>
>Subject: Time travel and cryonics
>Date: Sat, 19 May 2001 13:19:29 -0700

>I read the article on time travel from the link on Cryonet and was amused to
>note that whereas I had been privately informed by a well meaning Cryonet
>subscriber that the reported capability of actually slowing or stopping the
>speed of light was not actually what was going on, other scientists seem to
>think it is.  

That would be me. I'm puzzled by the apparent contradiction. but I was
reassured by this comment on another list:

< Photons don't "really" get slowed when they pass through a material
medium, whether a window pane or a Bose-Einstein condensate.  At some level
what happens is that they are constantly absorbed and re-emitted, with the
net effect of slowing the wave front.  Relativistic effects don't normally
slow down with the slowed photons; you can go FTL in a material medium, for
example, which is what causes Cherenkov radiation.  So I don't see how
slowing photons in this artificial way can have any effects in terms of
time travel or other relativistic phenomena. >

Damien Broderick

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