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View Full Version : Is there anything that's not moving?

wierdaaron
08-16-2009, 03:59 PM
Electrons move around atoms. Tectonic plates move around the surface of the planet, the planet spins like a top and rotates around the sun. Our solar system spins around inside the milky way, which itself spins around the universe.

It seems like as far back you pull or as close in as you zoom, everything is in motion. Is anything not moving? Is it possible that the universe or multiverse is just sitting there?

Could it be that motion is a universal constant, and it's as impossible for stillness to exist as it is for nothing to exist. Stillness seems to be defined as an absence of motion, the same way that cold is an absence of heat. In that way, there's no such thing as not moving.

Or should I put the bong down? I mean my friend's bong. I mean should he put down his bong?

dracoi
08-16-2009, 04:07 PM
I am not moving. In my frame of reference everything in the universe (including the universe) is moving relative to me.

Rhythmdvl
08-16-2009, 04:11 PM
I am not moving.

That's not what it looks like from here.

wierdaaron
08-16-2009, 04:11 PM
Have you met my associate, Galileo?

Chronos
08-16-2009, 05:25 PM
The first problem is the one that dracoi mentions: For anything that's not accelerating, you can attach your reference frame to that thing, define it to be stopped, and the laws of physics can't tell the difference. So the first thing you want to do is to choose what reference frame you think is most significant, or least arbitrary, or the like.

The closest you'll be able to find to that is something called the locally comoving cosmological reference frame. At any given point in the Universe, you can use the properties of the Universe's expansion to define a single logical reference frame. The problem with this is that it's a different reference frame at every point in the Universe. So even if Galaxy A is at rest in its own locally comoving reference frame, and Galaxy B is at rest in its locally comoving reference frame, Galaxy A will still be moving relative to Galaxy B and vice-versa.

EdwardLost
08-16-2009, 08:42 PM
my career

Exapno Mapcase
08-16-2009, 10:28 PM
Chronos, isn't it true that if something in the universe really weren't moving it could be used as an absolute reference point? And there can't be an absolute reference point?

HorseloverFat
08-16-2009, 11:52 PM
Space and time are the same thing. Relativity shows that there is no absolute time or space. So, no, there is no absolute reference point, unless you want to use pre-relativity physics.

Stealth Potato
08-17-2009, 12:12 AM
Chronos, isn't it true that if something in the universe really weren't moving it could be used as an absolute reference point? And there can't be an absolute reference point?

I don't know if we can even create a coherent definition for "not moving" that isn't just "not moving with respect to reference frame X." What exactly would it mean?

Have you met my associate, Galileo?

I tried, but he was moving too fast for me.

Indistinguishable
08-17-2009, 01:34 AM
Perhaps let's just ask if there are any two things which are not moving with respect to each other.

groman
08-17-2009, 06:13 AM
Mell most things will have some angular momentum even if you declare them to be not moving.

Boyo Jim
08-17-2009, 08:42 AM
Things chilled to absolute zero? And at the center of the Universe?

Exapno Mapcase
08-17-2009, 09:12 AM
That may be a whoosh. If not, there is no center to the universe and nothing can possibly be at absolute zero because of quantum uncertainties.

Really Not All That Bright
08-17-2009, 09:19 AM
That may be a whoosh. If not, there is no center to the universe and nothing can possibly be at absolute zero because of quantum uncertainties.
Quantum uncertainties = this thermometer sucks. :D

John DiFool
08-17-2009, 09:44 AM
my career

My bowels.

Boyo Jim
08-17-2009, 09:45 AM
My love life.

KarlGauss
08-17-2009, 10:54 AM
I am out of my league mentioning this, but from a purely mathematical, topological perspectve, I am pretty well certain that in a closed system of moving "things" there must be at least one point where things are at rest. A classic illustration of this is the fact that there must always be somewhere on the surface of the Earth where the wind is not blowing. I believe this is a consequence of a Fixed Point Theorem but dare not say more lest someone be fooled into thinking that I know what I'm talking about.

Giles
08-17-2009, 11:10 AM
I am out of my league mentioning this, but from a purely mathematical, topological perspectve, I am pretty well certain that in a closed system of moving "things" there must be at least one point where things are at rest. A classic illustration of this is the fact that there must always be somewhere on the surface of the Earth where the wind is not blowing. I believe this is a consequence of a Fixed Point Theorem but dare not say more lest someone be fooled into thinking that I know what I'm talking about.
I think you are talking about Brouwer's fixed point theorem, which assumes a continuous function from a convex compact space to itself. I'm not sure that motion in the universe is continuous (if it is, how can objects collide with each other?), or that the universe is a convex compact space.

Chronos
08-17-2009, 11:57 AM
A classic illustration of this is the fact that there must always be somewhere on the surface of the Earth where the wind is not blowing.That's an application of the Hairy Ball theorem, but that depends on the number of dimensions. It works on the surface of a sphere, but not on the circumference of a circle or the surface of a hypersphere, and I'm pretty sure it also doesn't apply to any of the possible shapes of our Universe.

CC
08-17-2009, 12:19 PM
Here, let me see if I can slow things down here. You ask a simple question and get a set of arcane answers. When you ask "Is there anything that's not moving?" you mean - even if you don't say it - "...compared to something else." Moving only means moving when you compare it to yourself or to something else. No object is moving if it's not being compared to something else. Go back to your "friend's" bong and see if there's a different version of the question you want to ask.