Can you determine absolute motion?

[curiousphoton]

This is not correct. Light always travels at c, you can't "add" a speed to it. So light would hit all the receptors at the same time.
Remember that EVERYONE will always measure the same speed of light(c).

I believe you are slightly incorrect. Yes, light always travels at c and yes, you can't "add" a speed to it as you've stated.

But saying 'light would hit the receptors at the same time' is misleading. Refer to 'Relativitey', Albert Einstein, Chapter 9. In Mr. Einstein's train example, imagine Points A and B are on the circumference of this thread's sphere. If a pulse is emitted from center-of-the-sphere point M, then either A or B will receive the pulse at a different time, even though C is constant.

 

[Physicist1231]

So if you have two people standing 20ls apart and one flashes a light. Both people know that they are 20ls apart.

We will put flasher at 0,0,0 to make things easy

It makes sense that all at rest light will be at 20ls,0,0 in 20 seconds. We KNOW that part.

Now with that same setup reciever is approaching at .5c. According to relativistic logic the light will hit him after 20seconds inwhich time he has traveled (.5c*20s= 10ls). about half the distace when the light intercepts him.

So now the photon is at both coordinates 20ls,0,0 AND 10ls,0,0 because someone pervieved it?

 

[Physicist1231]

I believe you are slightly incorrect. Yes, light always travels at c and yes, you can't "add" a speed to it as you've stated.

But saying 'light would hit the receptors at the same time' is misleading. Refer to 'Relativitey', Albert Einstein, Chapter 9. In Mr. Einstein's train example, imagine Points A and B are on the circumference of this thread's sphere. If a pulse is emitted from center-of-the-sphere point M, then either A or B will receive the pulse at a different time, even though C is constant.

THANK YOU! I have been asking that question for a long time and just modified that same scenario to see if anyone (believing in relativity) would get that. I really appreciate you bringing out that setup that he had. That was the basis of this conversation. So... Now the question becomes.

Is Einstein wrong in his scenario or is relativity's view of light wrong?

 

[curiousphoton]

THANK YOU! I have been asking that question for a long time and just modified that same scenario to see if anyone (believing in relativity) would get that. I really appreciate you bringing out that setup that he had. That was the basis of this conversation. So... Now the question becomes.

Is Einstein wrong in his scenario or is relativity's view of light wrong?

See: http://www.bartleby.com/173/9.html

Einstein's scenario decribes certain reasoning behind relativity's view of light, therefore asking 'Is Einstein wrong in his scenario or is relativity's view of light wrong', is akin to asking 'did Barry Bond's hit a home run or did Barry Bond's bat hit a home run.' Barry Bonds used his bat to hit a home run, much like Einstein used this scenario as a part of the development of relativity.

 

[Physicist1231]

See: http://www.bartleby.com/173/9.html

Einstein's scenario decribes certain reasoning behind relativity's view of light, therefore asking 'Is Einstein wrong in his scenario or is relativity's view of light wrong', is akin to asking 'did Barry Bond's hit a home run or did Barry Bond's bat his a home run.' Barry Bonds used his bat to hit a home run, much like Einstein used this scenario as a part of the development of relativity.

Ok I will grant you that (though i do not quite agree on the analogy). Regardless, you point brought out that the light would reach one location on the sphere sooner than the other if the apparatus was in motion.


This would mean you can have and define Absolute Motion. Am I correct?

 

[curiousphoton]

Ok I will grant you that (though i do not quite agree on the analogy). Regardless, you point brought out that the light would reach one location on the sphere sooner than the other if the apparatus was in motion.


This would mean you can have and define Absolute Motion. Am I correct?

No. Re-read the example. Light reaches Point A and Point B on the train at different times, t1and t2. But if a third train were introduced and it was moving at some constant velocity other than the original train, then light would reach its Point A and Point B at some other times, t3 and t4.

The point is that observers in different RF's record an event differently and none of the observers are incorrect, even though their results differ from one another.

Therefore, one cannot define Absolute Motion because there is no 'correct' or 'incorrect' RF.

 

[Physicist1231]

No. Re-read the example. Light reaches Point A and Point B on the train at different times, t1and t2. But if a third train were introduced and it was moving at some constant velocity other than the original train, then light would reach its Point A and Point B at some other times, t3 and t4.

The point is that observers in different RF's record an event differently and none of the observers are incorrect, even though their results differ from one another.

Therefore, one cannot define Absolute Motion because there is no 'correct' or 'incorrect' RF.

ok so let's say that points A and B were motionless and we know that they are equi-distant (only talking Equidistant reference points from a central location) If the apparatus was absolutely motionless it would light would reach all points at the same time. If the apparatus was in motion in any direction at any speed there would be a time difference reading. Using the same scenario. With only Equi-distant bodies. Just in a spherical formation around a central one.

 

[JesseM]

I believe you are slightly incorrect. Yes, light always travels at c and yes, you can't "add" a speed to it as you've stated.

But saying 'light would hit the receptors at the same time' is misleading. Refer to 'Relativitey', Albert Einstein, Chapter 9. In Mr. Einstein's train example, imagine Points A and B are on the circumference of this thread's sphere. If a pulse is emitted from center-of-the-sphere point M, then either A or B will receive the pulse at a different time, even though C is constant.

I think you yourself are being fairly misleading here, because you don't make clear that you mean "at a different time" only in one particular frame, the frame of the observer at rest relative to the tracks. In the frame of the observer at rest relative to the train, A or B do receive the pulses at the same time. And simultaneity is relative in relativity, so neither perspective is more "correct" in relativistic terms.

 

[JesseM]

do you have the math on that? Cause using Newtonian Physics (seems to be a cusw word on here some times then that Photon that was emitted would have reached all three individuals at the same time but each person is in a separate location. So thus that one photon is in X (number of reference points) places at the same time.

To understand what's going on here, you have to understand that each observer is using clocks at rest relative to themselves which have been synchronized according the the Einstein clock synchronization convention--the idea is that each observer defines two of their clocks to be "in sync" if they set a light flash off at the midpoint between the two clocks, and both clocks show the same reading at the moment the light strikes them, because each observer assumes that the light traveled at the same speed in both directions relative to themselves. But this necessarily implies that if I have two clocks which I define to be in sync, in your frame my two clocks must be out-of-sync! After all, suppose I am in a ship that is moving relative to you, with clocks at the front and back of the ship, and I set off a flash at the midpoint of the ship and set both to read the same time when the light strikes them. And suppose at the moment I set off the flash at the middle, the ship is passing by you, and you are right next to the flash as it happens, so in your frame you define your own position to be "the position where the flash occurred". In that case, since the ship is moving forwards in your frame, from your perspective the clock at the front of the ship is moving away from "the position where the flash occurred", while the clock at the back of the ship is moving towards that position! So if you assume that light moves at the same speed in both directions in your frame, then according to your own definition of simultaneity the light must catch up with the back clock before it catches up with the front clock. So if I set both clocks to read the same time when the light hits them, then in your frame the clocks must be out-of-sync, because the back clock will show that time at an earlier moment (in your frame) than the front clock. It works out that if the clocks are synchronized in my frame, and the distance between them in my frame is D, then if the ship is moving at speed v in your frame, then at any given instant in your frame the two clocks will be out-of-sync by an amount vD/c^2.

If you combine this equation for the out-of-syncness of moving clocks with the equation for length contraction, which says that a ruler of length L in my frame is shrunk to a length L*sqrt(1 - v^2/c^2) in your frame, and the equation for time dilation, which says that two ticks of my clock which happen at a time interval of T apart in my frame happen at an interval of T/sqrt(1 - v^2/c^2) in your frame (which is equivalent to saying that in your frame the rate at which my clocks tick is only sqrt(1 - v^2/c^2) the rate of your own clocks), then you can construct a simple example to show how both observers measure the speed of a single light beam to be 1c in their own frames, using their own rulers and synchronized clocks. Here is such an example:

Say there's a ruler that's 50 light-seconds long in its own rest frame, moving at 0.6c in your frame. In this case the relativistic gamma-factor of 1/sqrt(1 - v^2/c^2) is equal to 1.25, so in your frame its length is 50/1.25 = 40 light seconds long. At the front and back of the ruler are clocks which are synchronized in the ruler's rest frame; because of the relativity of simultaneity, this means that in your frame they are out-of-sync, with the front clock's time being behind the back clock's time by vD/c^2 = (0.6c)(50 light-seconds)/c^2 = 30 seconds.

Now, when the back end of the moving ruler is lined up with the x=0 light-second mark of your own ruler (which of course is at rest relative to you), you set up a light flash at that position. Let's say at this moment the clock at the back of the moving ruler (which is right next to the flash as it happens) reads a time of 0 seconds, and since the clock at the front is always behind it by 30 seconds in your frame, then in your frame the clock at the front must read -30 seconds at that moment, and it will be at a position of x=40 light-seconds since the ruler has a length of 40 ls in your frame. 100 seconds later in your frame, the back end will have moved (100 seconds)*(0.6c) = 60 light-seconds along your ruler and be at position x=60 ls, which means the front end will be lined up with the x=100 ls mark on your ruler. Since 100 seconds have passed, if the light beam is moving at c in your frame it must have moved 100 light-seconds in that time, so it will also be at the 100-light-seconds mark on your ruler, just having caught up with the front end of the moving ruler.

Since 100 seconds passed in your frame, then thanks to the slower rate of the clocks on the moving ruler this means 100/1.25 = 80 seconds have passed on the clocks at the front and back of the moving ruler. Since the clock at the back read 0 seconds when the flash was set off, it now reads 80 seconds; and since the clock at the front read -30 seconds, it now reads 50 seconds. And remember, the ruler was 50 light-seconds long in its own rest frame! So in its frame, where the clock at the front is synchronized with the clock at the back, the light flash was set off at the back when the clock there read 0 seconds, and the light beam passed the clock at the front when its time read 50 seconds, so since the ruler is 50-light-seconds long, the beam must have been moving at 50 light-seconds/50 seconds = c as well! So you can see that everything works out--if you measure distances and times with rulers and clocks at rest in my frame, you conclude the light beam moved at 1 c, and if a moving observer measures distance and times with rulers and clocks at rest in his frame, he also concludes the same light beam moved at 1 c.

For symmetry we can also consider that at the moment the flash was set off, there was a second ruler moving at 0.6c which was also 50 ls long in its own rest frame, but with its front end next to the position the flash was set off, which means at the same moment in your frame the back end will be next to the x=-40 ls mark on your ruler. If we assume the clock at the front end of the moving ruler read a time of 0 seconds when the flash went off, then according to the relativity of simultaneity, the clock at the back end must have read 30 seconds at the same moment in your frame.

25 seconds later in your frame, since the back end is moving at 0.6c it will have moved forward by (25 s)*(0.6c) = 15 light-seconds, so it will have moved from x=-40 to x=-25 along your own ruler. And if the light beam was traveling at c in your frame, then the beam will also be at x=-25 light seconds at that moment. And in 25 seconds, the clocks at the front and back only tick forward by 25/1.25 = 20 seconds, so at this moment in your frame the clock at the front reads 20 seconds while the clock at the back reads 50 seconds. So just like with the first ruler, the clock at the far end of the ruler (the one that wasn't right next to the flash when it happened) reads 50 seconds when the light hits it, and again the ruler is 50 light-seconds long in its own frame, and again in its own frame clocks at either end are defined to be "synchronized" and the clock next to the flash read 0 seconds when it happened. So from this you can hopefully see why an observer at rest relative to these rulers would conclude the light moved at the same speed of c in both directions from the flash, just as was true in your own frame.

 

[Physicist1231]

I think you yourself are being fairly misleading here, because you don't make clear that you mean "at a different time" only in one particular frame, the frame of the observer at rest relative to the tracks. In the frame of the observer at rest relative to the train, A or B do receive the pulses at the same time. And simultaneity is relative in relativity, so neither perspective is more "correct" in relativistic terms.

The time frames have already been established with the individual clocks on each photo receptors. Each one bying synced to the ones immediately surrounding it. Thus All timers are ticking the same time.

One point in that expiriment that I would like to use was that IF the apparatus (or train) were motionless in the absolute sense then according to his setup both A and B would percieve the light at the exact same absolute time. His train was in motion and the results were that one happened first. With that said the apparatus i mentioned WOULD work for its intended purpose!

 

[JesseM]

The time frames have already been established with the individual clocks on each photo receptors. Each one bying synced to the ones immediately surrounding it. Thus All timers are ticking the same time.

Read the beginning of my last post (#44). If the clocks are synched in their own rest frame, they are out-of-synch in other frames. There is no frame-independent way to "synch" clocks at different locations.

One point in that expiriment that I would like to use was that IF the apparatus (or train) were motionless in the absolute sense then according to his setup both A and B would percieve the light at the exact same absolute time. His train was in motion and the results were that one happened first. With that said the apparatus i mentioned WOULD work for its intended purpose!

No, it wouldn't. If A and B were using clocks that were synched in their own frame using the Einstein synchronization convention I discussed in my previous post, then they would show the same time when the light hit them regardless of whether they were at rest in the absolute sense or moving in the absolute sense. Please look over the numerical example in my previous post to see how this works (for the purposes of that example, feel free to imagine that you are at rest in the absolute sense while the other ruler is moving in the absolute sense--it makes no difference to the subsequent calculations, we still conclude that both of the moving clocks read a time of 50 seconds when the light from the flash strikes them)

 

[grav-universe]

To an observer with a relative speed, the photons will strike the back of the large sphere first because the light travels back at c while the back of the sphere moves toward the light at v, and then the light strikes the front of the sphere at a later time since the light travels forward at c while the front of the sphere travels away from the light at v, but that is just relativity of simultaneity. Observers in different inertial frames will not agree upon simultaneity issues. In the frame of the spheres, the light always strikes the large sphere simultaneously because that is how each inertial frame is synchronized to measure c with light traveling equal distances in equal times according to the Einstein simultaneity convention. We can only measure the relative speed between the spheres and the observer this way, not an absolute speed.

ETA - Oops, I guess this has been said. I thought there was only one page. :)

 

[Physicist1231]

So are you (jesseM) saying that you can never have anything syncronized in an absolute sense? Ever under ANY circum stances according to relativity?

If not, under what conditions can this exist?

The simplest definition that we will use for simultanious is two actions occurring at the same time. As needed we can set that "according to X this is simultanious. But really I am looking in the absolute form.

 

[jtbell]

Two events (e.g. "clock A reads 10:48:00 PM" and "clock B reads 10:48:00 PM") can be simultaneous in at most one inertial reference frame. Even this "single-frame simultaneity" is possible only if no signal traveling at a speed less than or equal to c can "connect" the two events. If such a signal can connect the two events, then they cannot be simultaneous in any inertial reference frame, because the signal would travel instantaneously in such a frame.

 

[Physicist1231]

By simple logic saying that things two thing happening at the same absolute time is a little of an outlandish statement.

You can set up an expiriment where you have two lights right next to each other. (say 1 foot apart) and put an observer anywhere. Now you can set each light to go off a a slightly different frequency. According the the observer Light A flashed before Light B. As the observer keeps watching, the interval time between flashes A and B becomes increasingly closer. and closer... until perhaps they appear syncronized according to the observer... it keeps going... Now the flashes are at a rapid pace but now B looks like it is flashing first. and the intervals between get longer and longer. This cycle can go on and on.

Now it may not have been the exact time that the observer thought they were syncronized but at some point in an absolute sense this was reached.

 

[DaveC426913]

Now it may not have been the exact time that the observer thought they were syncronized but at some point in an absolute sense this was reached.

But it is not absolute; it is dependent upon the observer.

Absolute doesn't simply means synchronous from one observer's point of view; it means 'all possible observers agree'.

Two observers watching your setup will disagree on the timing of events. Neither is absolute. Both are relative (there's that word again).

 

[russ_watters]

So are you (jesseM) saying that you can never have anything syncronized in an absolute sense? Ever under ANY circum stances according to relativity?

Yes! That's what the word "relativity" means!

The simplest definition that we will use for simultanious is two actions occurring at the same time. As needed we can set that "according to X this is simultanious. But really I am looking in the absolute form.

It just plain doesn't exist.

 

[JesseM]

So are you (jesseM) saying that you can never have anything syncronized in an absolute sense? Ever under ANY circum stances according to relativity?

Well, if one frame's definition of coordinate simultaneity happens to match absolute simultaneity (assuming such a thing as absolute simultaneity exists, I don't believe in it myself but that's a philosophical issue), then synchronizing clocks in that frame would also synchronize them in an absolute sense. But relativity says that even if an absolute frame exists, no experiment would tell us which frame is the one whose definition matches the absolute one--if we had many sets of clocks synchronized in many different frames, God might be able to point at some set of clocks and say "those are the ones that are absolutely synchronized", but we mere humans would have no way of knowing experimentally which set (if any) was the one that was absolutely synchronized.

 

[Physicist1231]

Absolute doesn't simply means synchronous from one observer's point of view; it means 'all possible observers agree'.

That is not true at all. Othewise there would be no absolute anything at all. (I am assuming this is your point though). As brought out in the previous setup it may not have been the same time PERCIEVED by the observer but rather that point of time where the clocks were truly and absolutely flashing at the same time. You know that according to the observer that he perceived Light A flash THEN Light B, Then they synced, then they were opposite. It happened somewhere in there... Questions is how to define it.

Logicly (as did Prof E.) he put a person (M) in the exact middle of two lightning pads (A and B). Provided the entire setup was at absolute rest the light would travel from each pad to the observer (equidistant from both) cover the same amount of distance (absolute distance) at the same velocity (absolute velocity of C) thus at the same time.

The only thing different about this limited point of view is that he is Equidistant from both events so he can accurately determinie simulnaity (spelling:() provided the entire body is at rest. Yet he would KNOW the entire setup was in motion if he knew he was equi distant and the light hit him at different times.

 

[Physicist1231]

Two events (e.g. "clock A reads 10:48:00 PM" and "clock B reads 10:48:00 PM") can be simultaneous in at most one inertial reference frame.

Not quite. You can have one plane of people (imageine a two dimensional plane of receptors) and have a light on either side that intersects with a striaght line and prependicular to the pane. You now have everyone equidistant to each light. Every one has their own distance from the lights but if they measure the distance between them and both lights they will find it is equal.

With this setup if both lights flash at the same time everyone on that plane will percieve it Simultaniously (at different points in time) but percieve that both flashed at the same time.

 

[DaveC426913]

That is not true at all. Othewise there would be no absolute anything at all. (I am assuming this is your point though).

Without letting it get too general, yes.

As brought out in the previous setup it may not have been the same time PERCIEVED by the observer but rather that point of time where the clocks were truly and absolutely flashing at the same time. You know that according to the observer that he perceived Light A flash THEN Light B, Then they synced, then they were opposite.

It happened somewhere in there... Questions is how to define it.

Yes. It is defined as relative to the observer.

Each observer sees a point where the flashing lights flash simultaneously but they disagree on when that is. Thus it is not absolute, it is relative to the observer.


Simply put, if two events are separated in space then their time is relative to the observer. Full stop.

You are still confused about the meaning of absolute. Just because one observer sees two events to happen simultaneously does not mean that is an absolute phenomenon. For something to be absolute requires that all possible observers will come to the same conclusion.

 

[Physicist1231]

You are still confused about the meaning of absolute. Just because one observer sees two events to happen simultaneously does not mean that is an absolute phenomenon. For something to be absolute requires that all possible observers will come to the same conclusion.

Absolute does not mean that ALL observers agree. Rather it is the difference between Actuallity and Perception. Observers can percieve something but that may not have been what ACTUALLY happened. Absoluteness in this sense is defining what is actually happening in space and time no matter how it is perceived by a limited reference point.

 

[Physicist1231]

No. Geometrically your setup does not work.

We can make it more simple.

Light A is at -10ls,0,0
Light B is at 10ls,0,0
Observer is at 0,0,0

Light A and B emit light at the same time

Provided that the entire setup is motionless the observer will see the lights flash at the same time

Move the observer to 0,5ls,0 and he will observe the same thing just takes a fraction of a second longer to see them.

Move to 0,5ls,5000ls and he will still observe that both happened at the same time. just takes a lot longer to see it.

 

[DaveC426913]

We can make it more simple.

Light A is at -10ls,0,0
Light B is at 10ls,0,0
Observer is at 0,0,0

Light A and B emit light at the same time

Provided that the entire setup is motionless the observer will see the lights flash at the same time

Move the observer to 0,5ls,0 and he will observe the same thing just takes a fraction of a second longer to see them.

Move to 0,5ls,5000ls and he will still observe that both happened at the same time. just takes a lot longer to see it.

Yes. you have shown that, relative to two observers of your choice, they agree that two events have occurred simultaneously.

So what?

That is not absolute. As witnessed by a third observer, who comes in with an equally valid observation and says the events occurred separate in time. And he'd be right.

You still don't get 'absolute'. It does not mean that two observers of your choice agree. Or a hundred. Or a thousand.

It means that their conclusions are independent of their position. i.e. your observers could move their position all they want (an infinity of choices) and still arrive at the same conclusion. That would make it absolute, instead of relative to their position.

 

[Physicist1231]

Two events (e.g. "clock A reads 10:48:00 PM" and "clock B reads 10:48:00 PM") can be simultaneous in at most one inertial reference frame. Even this "single-frame simultaneity" is possible only if no signal traveling at a speed less than or equal to c can "connect" the two events. If such a signal can connect the two events, then they cannot be simultaneous in any inertial reference frame, because the signal would travel instantaneously in such a frame.

Dave,

that setup was mainly for this quote here. not really defining absolute anything. He mentioned that things can only be perceived as simultanious ant at max one point at a time. I was simply showing otherwise.

 

[Physicist1231]

Yes. you have shown that, relative to two observers of your choice, they agree that two events have occurred simultaneously.

So what?

That is not absolute. As witnessed by a third observer, who comes in with an equally valid observation and says the events occurred separate in time. And he'd be right.

You still don't get 'absolute'. It does not mean that two observers of your choice agree. Or a hundred. Or a thousand.

You are correct so take out the "limited point of view" since they cannot be trusted. Toss something else into the mix. The Omnipotent Point of view. This view is not limited by space or time.

With this said this OPOV will be able to stop everything as if taking a 3d picture and can then traverse the environment (without time passing for any object).

To determine if Both light A and B flashed at the same time the OPOV analyses each frame of time taken.

This comes back to the difference between Actuality (absolute measurements) and Perception (how it is perceived by others).

In each time frame the OPOV goes to the exact location of Light A.

If light is present in that point in time then move to Light B.

If light exists at Point B then both lights are on at the same time.

He can then go back one unit of time (what ever that would be, second, microsecond, nanosecond ect) and where one moment of time both are off and the next moment in time they are perceived on (according to the OPOV as defined above) then this could be considered the the absolute sense that the lights flashed at the same point in time regardless of how they are perceived by a limited pov.

 

[DaveC426913]

that setup was mainly for this quote here. not really defining absolute anything. He mentioned that things can only be perceived as simultanious ant at max one point at a time. I was simply showing otherwise.

You're battling trivialities while missing the bigger picture.

 

[DaveC426913]

You are correct so take out the "limited point of view" since they cannot be trusted. Toss something else into the mix. The Omnipotent Point of view.

No!

They can be trusted! They are perfectly correct!

There is no omnipotent point of view!

Argh!

 

[DaveC426913]

You are correct so take out the "limited point of view" since they cannot be trusted. Toss something else into the mix. The Omnipotent Point of view. This view is not limited by space or time.
No such thing as omnipotent PoV

With this said this OPOV will be able to stop everything as if taking a 3d picture and can then traverse the environment (without time passing for any object).
No such thing as an absolute snapshot.

To determine if Both light A and B flashed at the same time the OPOV analyses each frame of time taken.

This comes back to the difference between Actuality (absolute measurements) and Perception (how it is perceived by others).
No such thing as an actual measurement.

In each time frame the OPOV goes to the exact location of Light A.
No such thing.

If light is present in that point in time then move to Light B.

If light exists at Point B then both lights are on at the same time.

He can then go back one unit of time (what ever that would be, second, microsecond, nanosecond ect) and where one moment of time both are off and the next moment in time they are perceived on (according to the OPOV as defined above) then this could be considered the the absolute sense that the lights flashed at the same point in time regardless of how they are perceived by a limited pov.

Physicist1231, this is a complete lack of understanding of Einsteinian spacetime. You are using a classical Newtonian model, where space and time are absolute and unchanging backdrops against which all things can be measured.

The classical Newtonian model has been replaced with the Einsteinian model, which has been shown to be correct in what is arguably the most well-tested theory in the history of science.

The very fundamental principle of Einsteinian relativity is exactly this: simultaneity of events is relative to the observer's frame of reference. All other phenom fall out of this one.

Your arguiments are all based on an out-of-date model that has been shown to be false in literally uncountable experiments.

 

[1MileCrash]

Honestly, I may catch some slack for this because relativity does not explicitly make this claim, but it is actually much easier to understand if you take it a step further in that not only can absolute motion not be measured, but it doesn't exist.

 

[jtbell]

He mentioned that things can only be perceived as simultanious ant at max one point at a time. I was simply showing otherwise.

In relativity, different "reference frames" refer to observers that are moving relative to each other. Two observers at different locations, and at rest with respect to each other, both observe the same two events to be simultaneous (or not), after correcting for signal-travel time from the events. Two observers that are moving with respect to each other, differ in their observation of the time interval between two events.

When we talk about a "reference frame" we are talking about the whole collection of possible observers that are stationary with respect to each other, and who are at rest in that reference frame.

 

[DaveC426913]

Honestly, I may catch some slack for this because relativity does not explicitly make this claim, but it is actually much easier to understand if you take it a step further in that not only can absolute motion not be measured, but it doesn't exist.

Good point.

(But if one were going to catch anything, it would be not slack, it would be flak. They're kind of opposites. )

http://en.wikipedia.org/wiki/Flak_(disambiguation)"

 

[1MileCrash]

Too early, they rhyme, close enough. :)

 

[jeppetrost]

Don't know if troll... or just very stubborn...

 

[DaveC426913]

Don't know if troll... or just very stubborn...

No call for that.