Space, the final...

Frontier. Yes, you thought i would replace frontier with something witty didnt you, the jokes on you-i am neither clever nor funny

The problem:

We are travelling through time, the 4th dimension at all times. Time and space are the same thing, so as we travel through space we travel through time, correct? if this is wrong, the problem itself is a load of rubbish - if all the planets and everything were to stop would we stop going through time? I would think that time would freeze until motion started again (eg when the universe stops expanding and starts compressing it is possible somewhere would reach exactly no velocity in any direction) but how owuld motion start again if time has frozen? i dont understand this and makes me think i must have got something majorly wrong. Any explanations please?

Is there ever a stillness?
And if there is, if there is a local stillness, does time behaves differently then?

In total vacuum, with no matter at all, is it toally still? Then is time standing still at those conditions?

In total stillness, is there a possibility to measure time then? And if not, is this a proof that the time stands still?

No, I think time is allways going, no matter what.

Originally posted by mazziewag
Frontier. Yes, you thought i would replace frontier with something witty didnt you, the jokes on you-i am neither clever nor funny

The problem:

We are travelling through time, the 4th dimension at all times. Time and space are the same thing, so as we travel through space we travel through time, correct? if this is wrong, the problem itself is a load ...[text shortened]... rstand this and makes me think i must have got something majorly wrong. Any explanations please?

Yes your assumption at the start is wrong and the question is a load of rubbish. Time is a dimention different to the three spacial dimentions so travelling through space does not nescicerally mean travelling through time, or vise versa.

Originally posted by danandi1
Time is a dimention different to the three spacial dimentions so travelling through space does not nescicerally mean travelling through time, or vise versa.

Your answer is right, but this little bit isn't quite true. It doesn't matter that it's difference to the other three, it could be the same and the answer would still be true. Take the three spacial dimensions, just because you're moving forward doesn't mean you're moving sideways or up/down. (This holds whatever your frame of reference, providing your co-ordinates are linearly independent)

Originally posted by Zeddicus
Your answer is right, but this little bit isn't quite true. It doesn't matter that it's difference to the other three, it could be the same and the answer would still be true. Take the three spacial dimensions, just because you're moving forward doesn't mean you're moving sideways or up/down. (This holds whatever your frame of reference, providing your co-ordinates are linearly independent)

so what part of my quote is incorrect?

Originally posted by danandi1
Time is a dimention different to the three spacial dimentions so ....

I may have read it wrong - sorry if so, but I read this bit as meaning that the answer was so because time was a fundamentally different dimension from the three which make up space, rather than just being linearly independent.

Originally posted by danandi1
so what part of my quote is incorrect?

One thing, there is preliminary evidence in the COBE MBR data that suggests the whole universe is spinning. If that is true it would change a lot of theories about the universe but it would also mean there wouldn't be any place not moving. Besides, even if a planet was motionless, you would still have motion inside, every molecule in a planet would be in motion, every electron cloud furiously flying around its nucleus, etc. There is also the motion of the various attractors, for instance, the whole galaxy is spinning around its own axis and that motion is on top of one where Andromeda galaxy is flying towards our galaxy at about 600 Km/sec because of gravitational attraction and we are also part of a galactic cluster moving towards another attractor yet to be fully identified, something hundreds of millions of light years away. Its like somebody stirring a cup of coffee, there is no place where there is no motion. Even at absolute zero tempurature there is molecular motion. So it would not matter if the universal expansion came to a screeching halt, there would be relative motion of every particle, every dust mote, every nebula, every cloud of hydrogen, every sun, every planet within that solar system. And like one poster said, you can have zero motion in one dimension and motion in another and its still moving. If something is spinning its moving in all dimensions at once or at least three out of 4, time plus two dimensions. In electron clouds, the cloud moves in all four dimensions at once so nothing can ever force anything in the universe to be totally still. Every motion in the universe effects every other motion due to gravitational attraction so the motion of a butterfly on earth still is felt on a galaxy a billion ly away, it just takes a billion years for that motion to effect that galaxy because gravitation moves at light speed. Even if you could somehow stop every planet, and every partical from moving in the entire universe, there would still be gravitation that would be creating distortions of space and time and would still be making motions, however small, due to gravity waves.

Originally posted by sonhouse
One thing, there is preliminary evidence in the COBE MBR data that suggests the whole universe is spinning. If that is true it would change a lot of theories about the universe but it would also mean there wouldn't be any place not moving. Besides, even if a planet was motionless, you would still have motion inside, every molecule in a planet would be in mo ...[text shortened]... tions of space and time and would still be making motions, however small, due to gravity waves.

What is the universe spinning relative to?

Originally posted by danandi1
What is the universe spinning relative to?

Its cos the giant tortoises are chasing their tails

Originally posted by danandi1
What is the universe spinning relative to?

An inertial frame?

Originally posted by mtthw
An inertial frame?

But if there is no stationary object in this frame then it has no meaning. You could say every object is spinning at every possible speed relative to a made up inertial frame.

Originally posted by danandi1
But if there is no stationary object in this frame then it has no meaning. You could say every object is spinning at every possible speed relative to a made up inertial frame.

Inertial frames can't rotate. They can only move at uniform velocity. That's why you can tell the Earth is rotating, rather than everything else in the universe revolving around us.

Originally posted by mtthw
Inertial frames can't rotate. They can only move at uniform velocity. That's why you can tell the Earth is rotating, rather than everything else in the universe revolving around us.

I never said they could. If you think my second sentance i wrong, what about the first, this still stands.

Also your second sentance is wrong whether the earth is spinning or everything move relative to us just dependt on the way you look at it - it is all relative - The universe sees us moving with respect to it and we see the universe moving with respect to us, neither is wrong.

Originally posted by danandi1
I never said they could. If you think my second sentance i wrong, what about the first, this still stands.

Also your second sentance is wrong whether the earth is spinning or everything move relative to us just dependt on the way you look at it - it is all relative - The universe sees us moving with respect to it and we see the universe moving with respect to us, neither is wrong.

This is true for linear motion, but rotation is more complicated. Look at Foucault's pendulum experiment - this will give qualitatively different results in the two cases of a rotating Earth and a rotating Universe. So it's not just a matter of how you look at it.

Because inertial frames don't rotate, we can define the rotation of an object with respect to "an inertial frame".

Originally posted by mtthw
This is true for linear motion, but rotation is more complicated. Look at Foucault's pendulum experiment - this will give qualitatively different results in the two cases of a rotating Earth and a rotating Universe. So it's not just a matter of how you look at it.

Because inertial frames don't rotate, we can define the rotation of an object with respect to "an inertial frame".

Sorry, you are probably correct - but does this mean that the universe can be defined as rotating with respect to an inertial frame assuming that the universe is evereything.