At 12:13 PM Friday 8/19/2005, Warren Ockrassa wrote:
On Aug 19, 2005, at 8:29 AM, Julia Thompson wrote:
Are we going through spacetime at the speed of light, basically?
Yes -- the combined velocity along the space and time vectors is
lightspeed. (I don't recall when exactly this realization was made clear
to me, but when it did get clarified, it made it a lot easier to
understand why FTL travel isn't possible in this universe. It also kind of
freaked me out.)
Asking, though, what the speed of time is is a lot like (exactly like)
asking what the speed of space is. Time, being a dimension, doesn't have a
speed. It's only your motion through it that applies the measure of speed.
When you're at rest, your motion in time is maximized to light's velocity.
When you move, some of the velocity on the time axis is diverted to
velocity in the spatial axes. That's why, if you're moving at a
significant velocity, you get the (relative) effects of time slowdown, but
of course only compared to the framework of others not moving so quickly.
As far as you're concerned, time is still moving at the same rate.
On Aug 19, 2005, at 2:16 AM, Andrew Paul wrote:
Ah, now there is the rub.. See, when people fly away from earth say, and
go fast, time slows down relative to us. And we are moving relative to
other places in the universe, so time is presumably going faster or
slower in said places.
If what you're thinking about here is cosmic expansion, it doesn't apply.
(Argh!) The universe itself -- its underlying structure -- is expanding,
which (argh! Ouch!) does not translate to velocity for the things carried
along in that expansion. So even if you pick a galaxy that's on the "far
side" of the universe from our own, one that's being carried away from us
at a maximum apparent velocity, you won't see time dilation for its
inhabitants relative to us or vice versa.
I was wondering if there are places where time is
going, relatively, slower than it is here, and this made me wonder, is
their like a maximum or minimum speed of time, and where would it occur.
Absolutely. Gravity is effectively acceleration, which means that time
near strong gravitational sources is slowed. And of course Earth's motion
around the sun and our system's motion around the galactic core will
contribute, in their own ways, to slowing down in time, but TTBOMK in
order for these kinds of effects to be noticeable as more than a few
seconds' difference over, say, a month or a year, you've either got to be
very near an extremely dense object (picture the current administration
and multiply by at least a factor of ten), or on a very fast-moving one.
Much faster than you normally see in astronomical objects.
Though the different rates of clocks due to the difference in gravity at
the Earth's surface and in LEO is something which must be taken into
account in order to provide accurate locations from GPS.
-- Ronn! :)
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