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> I saw an interesting lecture (Carl Sagan, I think?) who pointed out that
> if we were the size of insects, we'd barely notice gravity and we'd be
> much more concerned about surface tension, for example.
Yeh, this comes about because gravity forces, mass and inertia etc all scale
with length cubed, but surface tension scales with length squared. This is
an important concept in Engineering when making very small things.
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> That's a problem for time traveling. You have to travel in time yet stay
> in
> the same point in space. Oh wait, that would leave you in the middle of
> nowhere without an atmosphere. You have to stay in the same point in space
> *relative to your planet*!
And rotate with the planet, otherwise you might end up inside some mountain
or falling 500 metres towards the sea!
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scott wrote:
>> That's a problem for time traveling. You have to travel in time yet
>> stay in
>> the same point in space. Oh wait, that would leave you in the middle of
>> nowhere without an atmosphere. You have to stay in the same point in
>> space
>> *relative to your planet*!
>
> And rotate with the planet, otherwise you might end up inside some
> mountain or falling 500 metres towards the sea!
Hmm. But is your planet rotating? Or is your planet actually stationary
and the universe is rotating around it? ;-)
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>> Yes, I *own* the book. ;-)
>
> Where I come from, it'd be embarrassing to admit to that.<G> I read
> perhaps 30-40 pages before I tired of the Mathematica evangelism and
> megalomania. Sure glad libraries exist.
I don't recall much actually being mentioned about Mathematica. I do
recall thinking it was perhaps a tad arrogant to declare that all of
science and mathematics is wrong and that you are right.
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> Hmm. But is your planet rotating? Or is your planet actually stationary
> and the universe is rotating around it? ;-)
Does "stationary" actually mean anything in absolute terms?
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scott wrote:
>> Hmm. But is your planet rotating? Or is your planet actually
>> stationary and the universe is rotating around it? ;-)
>
> Does "stationary" actually mean anything in absolute terms?
That's kind of my point.
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>> Does "stationary" actually mean anything in absolute terms?
>
> That's kind of my point.
Actually for rotation, you should be able to define stationary. Because in
order to rotate you need some force to stop you flying off in a straight
line. On the surface of the Earth, the downwards force that you feel is
ever so slightly less than what it should be due to gravity, because the
Earth is rotating. If the Earth rotated at the right speed then there would
essentially be no downwards force (at least on the equator) and everything
would float.
So, assuming you can measure forces and calculate gravity accurately enough,
you should be able to determine if you are rotating or not, and how fast you
are rotating.
Another method might be to use a gyroscope, it will react differently if the
planet you are on is rotating or not.
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Invisible wrote:
> Hmm. But is your planet rotating? Or is your planet actually stationary
> and the universe is rotating around it? ;-)
The planet is rotating.
http://en.wikipedia.org/wiki/Foucault_pendulum
Didn't you ever go to a science museum? :-)
--
Darren New / San Diego, CA, USA (PST)
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Darren New wrote:
> The planet is rotating.
> http://en.wikipedia.org/wiki/Foucault_pendulum
> Didn't you ever go to a science museum? :-)
Sadly, the science museum near us doesn't even have one of these.
--
~Mike
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Darren New wrote:
> Kevin Wampler wrote:
>> If I recall correctly, the specifics of the possibilities he suggest
>> for how the current laws of physics can be computed by a CA are also
>> provably wrong under a rather reasonable set of assumptions.
>
> I'd like to see that link. Sounds interesting.
>
> But, yeah, I think the ones I've seen that are close to right are
> networks with the distance between nodes being roughly plank length, and
> the only important thing is the number of links coming from each node
> and where they go. Not quite "cellular" as such, but similar.
I'm not sure that this is the same paper I was thinking of, but if not
it seems to have more or less the same content. The interesting bit is
in section 3 and in particular subsection 3.2:
http://arxiv.org/abs/quant-ph/0206089
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