# 0 Velocity?

## Recommended Posts

OK, I have a question here.

If getting close to the speed of light distorts how time is percieved(slows time down), then what about not moving at all, compaired to how we perceive time.

We are moving. Exactly how fast can be up for debate. Studies have shown the milky way is moving at 370 miles per second(Relative to other galaxies). The solar system, is also moving within that system, and the earth is moving there within. I see that it could be also possible that all of the galaxies we know of are moving at a rate, relative to something else we are not aware of, and therefore cannot calculate that speed.

So my question is, ... if we are moving so fast, how would time be distorted if we were to not be moving at all?

• Replies 63
• Created

#### Popular Days

time would run faster at 0mph

##### Share on other sites

We are always stationary in our own frame of reference. Moving or not moving only has an effect if you are comparing clocks with someone else in some way. If the galaxy stopped rotating for some reason it would not affect our clocks at all - it would only have an effect for an outside observer who was looking at our clocks.

##### Share on other sites

fair point, but i think by time we mean in relation to aymptiomatically flat time, or any time which does not change when we do

##### Share on other sites

According to Einstein, none of us are stationary at all. We're all moving at the speed of light, it's just that most our momentum is being translated along the Time axis. Two people sitting side-by-side aren't actually sitting still -- they're moving through space-time at the same rate and along the same vector. If one of them moves off in another direction, then some of his momentum has been taken away from T in order to be translated along X, Y and/or Z. Thus he appears to have not moved as far along in time as the first person.

(Photons, on the other hand, move entirely along the X/Y/Z axes, and never along T, which is why they always seem to be moving at the same, unchangable speed.)

If you look at it that way, rather than try to memorize various paradoxes and their resolutions, not only will relativity make a lot more sense, but much of quantum mechanics and particle physics will drop neatly into place as well.

##### Share on other sites

Hmmm, thats an interesting way of looking at it Pangloss. Know where I can read more about that?

##### Share on other sites

Brian Greene's "The Elegant Universe". I was just talking about this in another thread, I didn't know this stuff myself, I've just been reading it over the last week or so. Great book.

(Wait... I just made it up out of thin air! Really! I'm a genius! No? What do you mean you don't believe me?!)

##### Share on other sites

According to Einstein' date=' none of us are stationary at all. We're all moving at the speed of light, it's just that most our momentum is being translated along the Time axis. Two people sitting side-by-side aren't actually sitting still -- they're moving through space-time at the same rate and along the same vector. If one of them moves off in another direction, then some of his momentum has been taken away from T in order to be translated along X, Y and/or Z. Thus he appears to have not moved as far along in time as the first person.

(Photons, on the other hand, move entirely along the X/Y/Z axes, and never along T, which is why they always seem to be moving at the same, unchangable speed.)

If you look at it that way, rather than try to memorize various paradoxes and their resolutions, not only will relativity make a lot more sense, but much of quantum mechanics and particle physics will drop neatly into place as well.[/quote']

That is a very "elegant" way of looking at everything, but it seems to lead to one problem. This makes the time dilation dependent on some absolute motion in 3-space. Actually, it makes time an absolute, along with 3-space. They just trade momentum back and forth. This is no longer relativity.

Let's say two people (clocks) are moving along the X-axis at some rate (10,000 mph), and their momentum along the T-axis is reduced in order to accomplish that translation. They are both moving together, and their clocks are running at the same rate. One of them then decelerates along the X-axis. He is then moving at 5,000 mph along the X-axis. Since he is then moving slower in the X,Y,Z frame, his momentum in T should increase (his clock should run faster). This makes the clock rate dependent on its absolute velocity in 3-space.

How does this match with relativity?

##### Share on other sites

Let's say two people (clocks) are moving along the X-axis at some rate (10' date='000 mph)[/b'], and their momentum along the T-axis is reduced in order to accomplish that translation. They are both moving together, and their clocks are running at the same rate. One of them then decelerates along the X-axis. He is then moving at 5,000 mph along the X-axis. Since he is then moving slower in the X,Y,Z frame, his momentum in T should increase (his clock should run faster). This makes the clock rate dependent on its absolute velocity in 3-space.

How does this match with relativity?

10,000 mph with respect to what? You've assumed an absolute velocity to make a conclusion about absolute velocity. All you know initially is that the clocks are not moving with repsect to each other.

##### Share on other sites

10' date='000 mph with respect to what? You've assumed an absolute velocity to make a conclusion about absolute velocity. All you know initially is that the clocks are not moving with repsect to each other.[/quote']

swansont - you're "absolutely" right

##### Share on other sites

I've got a question, and I'd start another thread, but my profile doesn't seem to want to let me do that.

What does the theoretical speed limit of "c" apply to? I've seen it posted that matter cannot reach the speed of light. I'm assuming that, since we're talking relativity here, that means two frames of reference cannot move away from one another at "c", if those frames are constructed of something physical.

So that means that two reference frames, however unrelated, can never move away from one another at speeds >= c? Is that right?

If that's right, I have another question. What possible physical limit can be placed on the motion of an object wrt any unrelated frame of reference? Basically, how can you place a real, physical limit on something based only on the choice of reference frame?

I could be way off here, but I figured I'd ask.

##### Share on other sites

I've got a question' date=' and I'd start another thread, but my profile doesn't seem to want to let me do that.

What does the theoretical speed limit of "c" apply to? I've seen it posted that matter cannot reach the speed of light. I'm assuming that, since we're talking relativity here, that means two frames of reference cannot move away from one another at "c", if those frames are constructed of something physical.

So that means that two reference frames, however unrelated, can never move away from one another at speeds >= c? Is that right?

If that's right, I have another question. What possible physical limit can be placed on the motion of an object wrt any unrelated frame of reference? Basically, how can you place a real, physical limit on something based only on the choice of reference frame?

I could be way off here, but I figured I'd ask.[/quote']

Any object with mass in an inertial reference frame cannot acvhieve c. Causally connected things cannot move faster than c.

##### Share on other sites

Don't forget that time is relative to the observer.

##### Share on other sites

So no physical object in the universe is moving away from any other physical object at c? Now from a third party, can those two physical objects be seen to be moving away from one another at c?

##### Share on other sites

Any object with mass in an inertial reference frame cannot acvhieve c. Causally connected things cannot move faster than c.

This is not true if simultaneity isn't relative Mr Swanson, you could specify that.

##### Share on other sites

This is not true if simultaneity isn't relative Mr Swanson, you could specify that.

There's really no need to make such caveats when discussing physics that has been demonstrated to be valid for over 100 years. It's like demanding that one specify that the moon is not made of green cheese when discussing astronomy. Or a Warning: This product is safe to eat label on your food.

If you insist on using a title, please us the correct one, (Dr) though addressing me by my user name is perfectly fine.

##### Share on other sites

So no physical object in the universe is moving away from any other physical object at c? Now from a third party, can those two physical objects be seen to be moving away from one another at c[/b']?

Yes, up to but not including, 2c. (locally)

(first question is no anyway due to Hubble but yes locally in either objects rest frame)

##### Share on other sites

There's really no need to make such caveats when discussing physics that has been demonstrated to be valid for over 100 years. It's like demanding that one specify that the moon is not made of green cheese when discussing astronomy. Or a Warning: This product is safe to eat label on your food.

If you insist on using a title' date=' please us the correct one, (Dr) though addressing me by my user name is perfectly fine.[/quote']

Ok Dr, but you know... oh nevermind.

Regards

##### Share on other sites

So no physical object in the universe is moving away from any other physical object at c? Now from a third party, can those two physical objects be seen to be moving away from one another at c?

Note that I said inertial frame, which means that special relativity applies. On large scales you have to use general relativity, and space itself is expanding. Locally nothing is travelling faster than c, but that motion is superimposed on an expanding space, which means you can get recessional velocities that exceed c.

##### Share on other sites

If you insist on using a title' date=' please us the correct one, (Dr) though addressing me by my user name is perfectly fine.[/quote']

Can we call you "Doc"?

##### Share on other sites

Can we call you "Doc"?

I suppose, though it would be a foreign experience so I might not respond to it. (The only PhD where I've worked that insisted on being addressed by Dr was someone who got a degree from an unaccredited school)

##### Share on other sites

So no physical object in the universe is moving away from any other physical object at c? Now from a third party' date=' can those two physical objects be seen to be moving away from one another at c?[/quote']Yes, up to but not including, 2c. (locally)

(first question is no anyway due to Hubble but yes locally in either objects rest frame)

Is that really true ? Can't the Third party speed limit be higher ?

I will try to make a reference frame where 2 objects will "distance" themselves higher in opposite directions.

(Just to learn not to prove anything.)

The frame includes Two dimensions.

In the center of the frame there is a tower where all measurements are made.

The tower could be considered at standstill and includes the only observer.

West of the tower is a platform moving from North to South with a measured speed of 0.99c.

On the West platform is a second platform moving from East to West with a measured speed of 0.99c.

Using Pythagoras this second platform is moving away from the tower with 1.4c.

East of the tower is a third platform moving from South to North with a measured speed of 0.99c

On the East platform is a fourth platform moving from West to North with a measured speed of 0.99c

Using Pythagoras this fourth platform is moving away from the tower with 1.4c.

Now from the observers perspective, inside the tower, will not the second and the fourth platform "distance" themselves at a rate of 2.8c ???

##### Share on other sites

Is that really true ? Can't the Third party speed limit be higher ?

I will try to make a reference frame where 2 objects will "distance" themselves higher in opposite directions.

(Just to learn not to prove anything.)

The frame includes Two dimensions.

In the center of the frame there is a tower where all measurements are made.

The tower could be considered at standstill and includes the only observer.

West of the tower is a platform moving from North to South with a measured speed of 0.99c.

On the West platform is a second platform moving from East to West with a measured speed of 0.99c.

Using Pythagoras this second platform is moving away from the tower with 1.4c.

East of the tower is a third platform moving from South to North with a measured speed of 0.99c

On the East platform is a fourth platform moving from West to North with a measured speed of 0.99c

Using Pythagoras this fourth platform is moving away from the tower with 1.4c.

Now from the observers perspective' date=' inside the tower, will not the second and the fourth platform "distance" themselves at a rate of 2.8c ???[/quote']

If you are in a set of inertial frames the Lorentz transform/velocity addition applies and none of the speed will exceed c. If you want to see anything with v>c you have to be in a situation where GR applies and have space expanding.

##### Share on other sites

If you are in a set of inertial frames the Lorentz transform/velocity addition applies and none of the speed will exceed c. If you want to see anything with c>v you have to be in a situation where GR applies and have space expanding.
I am not in a set of frames here, only one, which all measurements are made in, thus no velocity transforms should be necessary. Maybe I should have clearified better that the plattforms are attached to eatch other...

( "c>v" misstype, should be "v>c" or "c<v" ? )

Anyway I have already realized my misstake, if the platforms are attached to eatch other then the speed between any platform and the tower would be below c, thus the maximum speed the second and the fourth platform "distance" themselves with would be just below 2c, (in this frame).

Which was exactly what J.C.MacSwell posted.

## Create an account or sign in to comment

You need to be a member in order to leave a comment

## Create an account

Sign up for a new account in our community. It's easy!

Register a new account

×

• #### Activity

×
• Create New...

## Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.