[ExI] Relativity in Linearly Moving and Rotating Frames
lcorbin at rawbw.com
Mon Sep 29 07:25:05 UTC 2008
Damien B writes
>>>once you grasp that the Earth is rotating once a day,
>>>how obvious is it which body is orbiting the other?
>>One is supposed to be able to shut oneself up in a laboratory
>>and confirm whether or not one is in an accelerated frame.
> Yes, but I don't happen to have one about my person. Nobody
> does. We "know" naively that the sun spins around the earth
> because we *see* the bloody thing moving while *we're* plainly
> not moving.
There is much that we have learned about the world that is
not evident to our senses. Does one also equally doubt that
the continents float? Has anyone ever seen a continent float?
Do you think that a proton is made of three qworks (well,
that's how it's supposed to be pronounced)? Etc.
The entire realist program rests on the assertion that it is
possible for us to have very little doubt about a lot of things
that we have deduced only very, very indirectly. And yet,
how is that possible? It's only because the alternatives are
And we do not forget that all knowledge is conjectural only,
that all hypotheses are provisional and tentative. Yet, still, we
believe. We must believe. You must allow a doctor to stick
a needle in your arm and complete a sort of magic ritual. Why?
Because we have made many, many conjectures that have
withstood the test of time, and have never been successfully
criticized. So we find ourselves having no choice but to believe,
if we are going to be honest with ourselves.
> Which has nothing at all to do with which one orbits the other,
> but gave almost all humans the overwhelming impression that
> it does. Now, when we break free of that motionless flat earth
> illusion, but before we set up huge slow pendulums, I'm not
> sure it's all that obvious that the earth orbits the sun. I mean,
> the planets cavort back and forth, so they're special cases,
> break out the epicycles...
You are *so* right! Many, many honest and learned men refused
absolutely to believe anything so preposterous as that the Earth
moved, or that the stars did not circle the Earth every day. All
the evidence that it does move and they do not is indirect.
Yet it survives criticism. It's the last theory standing among all the
others. The rest of them ran afoul sooner or later, of evidence or
> , Jim, but both sun and moon plod along in much the same way,
> yet we're meant to intuit that one orbits earth and the other doesn't.
I don't think that we're meant to intuit it at all. On a dark night as I
look up towards Sagittarius, and then cast my eye to the left (since
I live in the northern hemisphere) about ninety degrees to Deneb,
I try as hard as I can to intuit what I know to be true: Deneb is only
1400 or so light years ahead of us, as we both circle around the center
of the vast visible Milky Way. Sometimes I can "see" it, but only for
> (Well, one's bright all the time and the other waxes and wanes,
> which is a clue--but what if we orbited Jupiter instead? Gets tricky, neh?)
Yar. Haven't a lot of SF stories had intelligent races evolve on cloud
enshrouded planets, or on such primary-secondary-tertiary systems
which take their astronomers almost forever to figure out? I remember
that Coeurl's race http://en.wikipedia.org/wiki/Coeurl didn't have any
planets besides their own, and didn't never did have the idea of
> I suspect most of us non-scientists "know" the true answer only
> because we've been told repeatedly since childhood.
It's the whole "network of knowledge" thing. W. V. Quine and
J. S. Ullian wrote a book about it, I think, called "The Web of Belief "
though I have not read it. ("So many books, so little time" as my
friend's t-shirt says.)
We go with the lesser miracle, whether it's a Moon Hoax or the
Loch Ness Monster. And we must occasionally find that what
"everyone knew" turns out eventually to get shot down in flames.
P.S. Sorry for the preachy tone, but I'm pretty upset with some
people at work right now, and am planning grandiose speeches,
denunciations, and confrontations galore. Savonarola will have
nothing on me come Wednesday.
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