From Newsgroup: rec.arts.drwho.moderated
From Address: jameskuyper@verizon.net
Subject: Re: "The Angles take Manhattan" - ground transport?

On 10/07/2012 10:43 AM, eleven@fish.net wrote:
> In article , jameskuyper@verizon.net says...
>> Time travel might actually be impossible, but so long as top physicists
>> are seriously debating the issue, stories postulating that it can
>> actually be done are entirely legitimate science fiction.
>>
> 
> Top scientists are therefore wasting their time and no doubt "public" 
> money.
> "time" is an abstract concept not something you can travel through.
> Top scientist are therefore just writing mathematical science fantasy.

Wow. Most ordinary objects travel through time at a constant rate of 1
year per year - but if you were making any kind of sense, that would
imply that this forward time travel must also be an illusion of some kind.

With just as much (or as little) sense, I could say the same thing,
replacing "time" with space, thereby justifying the claim that it's not
possible to travel through space.

Einstein's special theory of relativity reduced the distinctions between
time and space, replacing both concepts with a four-dimensional
space-time - and that replacement ultimately led to equations that
describe the release of nuclear energy from a nucleus (whether from the
Sun, nuclear bombs, or nuclear power plants) - but that must all be a
fantasy - many of the people who were living in Nagasaki and Hiroshima
in 1945 must still be alive, and will be grateful to learn that their
deaths were just imaginary. The Sun going dark will, however, interfere
with their joy at their continued survival.

Einstein's general relativity changed space-time from an inanimate
background to an active participant in physics. Massive objects change
the shape of space-time, and the shape of space-time causes objects to
move in curved paths (called geodesics) even when no forces are applied
to them, the same phenomenon that Newton's theory of gravity explained
in terms of gravitational force. General Relativity can be used to make
many predictions about gravity that are somewhat different from those
made by Newtonian gravity, and many of those predictions have been
confirmed, none have failed.

In particular, GR predicts the existence of traveling distortions in the
shape of space-time called gravitational waves, which can carry energy,
momentum, and angular momentum. Gravitational waves are inherently very
weak and difficult to detect; they have not yet been directly detected.
However, if GR is correct, close binary pulsars should emit large
amounts of gravity waves. The lost energy and angular momentum should
cause their orbital periods to decay at a rate that can be both
predicted and measured with considerable accuracy. Those predictions
match those measurements - but that must also be a fantasy, right? After
all, those pulsars can't actually be shining brightly enough to be seen
from Earth - that would require the release of nuclear energy, which is
also a fantasy.
-- 
James Kuyper

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