Re: Physicist Discovers How to Teleport Energy - MIT Technology Review

[David Farber <dave () farber net>]

Begin forwarded message:

From: David Byden <farber2 () byrden com>
Date: February 8, 2010 8:14:47 AM EST
To: dave () farber net
Subject: Re: [IP] Physicist Discovers How to Teleport Energy - MIT Technology Review


Dave:

I take issue with this statement in the article:
"a measurement on one particle immediately influences the
other, even though they are light-years apart."
I've seen this statement repeated in dozens of articles about
teleportation, and it shows that the author is out of his or her depth.

My beef is: what does 'immediately' mean?

Relativity theory tells us that there is no single frame of reference pervading
the universe; nobody can claim that they are at rest while the rest of us are
moving.  For much the same reason, there is no universal "now"; no single
instant of time shared by everyone. Events at separate locations that seem
coincident to one observer can occur in either order (A then B, or B then A)
for other observers, even allowing for the time it takes light to reach them.

To really grasp what's going on here and what its limits are, imagine this;
a special die is thrown on Earth and, by prearrangement, another is thrown on
a distant planet. Through a strange quantum process, both dies show the
same number - but nobody knew in advance what the number would be.
Now, obviously, such a mechanism cannot be used for faster-than-light
communication, and it does not matter which die is thrown "first" in any
observer's frame of reference.

David





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