Just a question that has confused me somewhat:

For one hour [earth frame time] an object holds a vector at the velocity of 0.9c.

What distances have been covered?

a] From our objects frame?
b] From an Earth stationary frame?

or to put it another way
our object is traveling 0.9c faster than our relatively stationary object [traveling at 2 kms perhour]

I get the impression and I am probably wrong that the object will have travelled just about the entire universe with in that hour from it's perpective however from an earth frame it would have travelled considerably less.

So if we stop our object after one hours flight where is it relative to the starting point?


We do the same calculations from one minutes travelling time and compare of a scale all the way to one hour and beyond if you like.....

For one hour [earth frame time] an object holds a vector at the velocity of 0.9c.

What distances have been covered?

a] From our objects frame?
b] From an Earth stationary frame?
In the rest frame of Earth:
An object leaves Earth at 0.9c for one hour then stops.
The object has travelled 3240 light-seconds.
Earth has not moved at all.

In the rest frame of the moving object:
Before the experiment, the object is moving with the Earth at -0.9c.
The object stops at t=0,
waits for 26 minutes and 9 seconds while the Earth continues moving at -0.9c,
then takes off at 0.9c again as the experiment ends.
During the experiment, the object did not move at all.
The Earth moved -1412 light-seconds.

I get the impression and I am probably wrong that the object will have travelled just about the entire universe with in that hour from it's perpective however from an earth frame it would have travelled considerably less.
The object was "moving" for less than an hour from its perspective.

so you are saying that the earth the sun and the entire universe is moving at -0.9c
relative to our object if our object is at rest.

the earth is obviously not going to move realtive to the universe that it exists in is it?

So to take the frame that the object is at rest and the entire universe is moving at -0.9c means what?

The object stops at t=0,
waits for 26 minutes and 9 seconds while the Earth continues moving at -0.9c,
then takes off at 0.9c again as the experiment ends.
During the experiment, the object did not move at all.
The Earth moved -1412 light-seconds.

Why would the earth have to stop and such.

BUt anyway the probelm is in the diomensional collapse.

How contracted is the universe for our object at 0.9c for one hour...

If we take a snap shot of a single moment at 0.9c how wide is the universe?

Say we give it a percentage of ...eh what, 10% of uncontracted universe.

That would mean that the uiniverse for our object is around say 118billionly*0.1
now what I would like to know is what happens if this object holds this velocity for an hour? how contracted can a contracted universe become?

The thinking:

If an object at v=c means that length has contracted to zero the universe is two dimensional to our object. Thus the diameter of the universe is zero.

So one could surmise that at a v=0.9c the universe is certainly very contracted. BUT the most important thing is that this is only for an instant of time. I wanted to know what would our object see if it held it's 0.9c for an hour.

so you are saying that the earth the sun and the entire universe is moving at -0.9c
relative to our object if our object is at rest.

the earth is obviously not going to move realtive to the universe that it exists in is it?

So to take the frame that the object is at rest and the entire universe is moving at -0.9c means what?

You're assuming some absolute rest frame, defined in some undetermined way by "the universe".

No such absolute rest frame exists. Both Earth and the object are equally entitled to say that the are at rest in the Universe, and the the other is moving.

Why would the earth have to stop and such.
It doesn't. The object stops. The Earth is moving constantly at 0.9c.

How contracted is the universe for our object at 0.9c for one hour...
48.5%. But not for one hour - the object is only stoped for 26 minutes.

You're assuming some absolute rest frame, defined in some undetermined way by "the universe".

No such absolute rest frame exists. Both Earth and the object are equally entitled to say that the are at rest in the Universe, and the the other is moving.
Pete I do understand that relativity states the frame object is at rest and the earth is moving. Using this frame perspective.
Where I get caught up is that if the object is deemed stationary then the entire universe is moving at 0.9c not just the earth......so often when switching frames we seem to forget that when doing so the rest of the universe switches frames as well.

If we consider the universe as a closed system then when say Object A is at rest then object B has velocity. but at all times the universe is there wondering what the f**k is going on....sort of....

if our object in the scenario is travelling at 0.9c with earth at rest then the sun is also at rest with the earth and the solar system is also , the galaxy and so on....because changing frames does not change the relationship the rest frame has with it's environment.

Now the scenario experiment was:

For one hour [earth frame time] an object holds a vector at the velocity of 0.9c.

What distances have been covered?

a] From our objects frame?
b] From an Earth stationary frame?

and I asked why the need to stop either frame when 1 hours continuous travel is called for?

Where I get caught up is that if the object is deemed stationary then the entire universe is moving at 0.9c not just the earth
You're assuming the Earth is stationary in the Universe.

How do you know that the object isn't stationary in the Universe, and that when we pretend the Earth is stationary, we're making the whole Universe move at 0.9c?

and I asked why the need to stop either frame when 1 hours continuous travel is called for?
Because the term "1 hour" is useless without an associated frame.

How do you know that the object isn't stationary in the Universe, and that when we pretend the Earth is stationary, we're making the whole Universe move at 0.9c?

MAybe we should make the universe move with our objet ...ha...that way it wont run into anything....but then again maybe the Earth would be run into.

The frame must include a universal reference surely otherwise the absurd rules supreme.

If earth is moving then it is destroyed unless teh universe moves with it. However our object has no such restraints.

It can move with out the solar system and the galaxy etc. But the earth is part of a larger system and not so easilly moved....gravitational forces being so significant etc....


Because the term "1 hour" is useless without an associated frame.
Possibly you have misread my intent.

I stated one hour in both frames.

object and earth

QQ,
how can you tell if the Universe is moving?
Surely you can only measure speed relative to individual objects?

I stated one hour in both frames.
Then you're talking two different scenarios... I though you were talking about a single experiment.

tis ok Pete I have got an answer in another thread "transfroms with in a frame"