Track of the light in a moving light clock.

[rajeshmarndi]

There is a moving light clock at a certain velocity. For an outside observer, the light just seemed to be traveling in a slant path. So far, it is right for the outside observer, the light is going in a slant path and hitting the top bar and then again returning and hitting the bottom bar.

Now, suppose the moving light clock changes its velocity periodically, then if I'm right, the track of the light now for the outside observer, will be, as if it is following and changing its track, as if the light knows when to change the track. How would the outside observer explain, the changing of the track of light in the space?

I hope I have made my question clear.

What is it, I'm not understanding here?

Thanks very much.

 

[Bill_K]

Now, suppose the moving light clock changes its velocity periodically, then if I'm right, the track of the light now for the outside observer, will be, as if it is following and changing its track, as if the light knows when to change the track.

It doesn't. As long as the clock is moving uniformly, everything is fine. A photon from mirror A aimed at mirror B will hit mirror B. But if you launch the photon, and then speed up, then obviously the photon will miss the mirror!

 

[terberculosis]

The light clock thought experiment was used as an example of special relativity, which only covers inertial reference frames. Inertial reference frames are situations which involve constant velocity. No acceleration or gravitational fields allowed.

Your proposed situation falls under the domain of General Relativity, because of the changing velocity. The photon would miss the second mirror if the acting force did not also act on the photon.

If I recall correctly, general relativity indicates that if the clock is accelerated by a constant gravitational field perpendicular to the travel path of the photon, the clock would still function with the path you indicated.

 

[Bill_K]

The light clock thought experiment was used as an example of special relativity, which only covers inertial reference frames. Inertial reference frames are situations which involve constant velocity. No acceleration or gravitational fields allowed.

Your proposed situation falls under the domain of General Relativity, because of the changing velocity. The photon would miss the second mirror if the acting force did not also act on the photon.

If I recall correctly, general relativity indicates that if the clock is accelerated by a constant gravitational field perpendicular to the travel path of the photon, the clock would still function with the path you indicated.

Special Relativity does not just cover inertial reference frames. It is perfectly adequate to deal with acceleration. General Relativity is a curved space theory of gravity.

 

[Dale]

The light clock thought experiment was used as an example of special relativity, which only covers inertial reference frames. Inertial reference frames are situations which involve constant velocity. No acceleration or gravitational fields allowed.

Your proposed situation falls under the domain of General Relativity, because of the changing velocity.

As Bill_K said this is a common misconception. Here is a good FAQ on the topic.
http://math.ucr.edu/home/baez/physics/Relativity/SR/acceleration.html

 

[rajeshmarndi]

It doesn't. As long as the clock is moving uniformly, everything is fine. A photon from mirror A aimed at mirror B will hit mirror B. But if you launch the photon, and then speed up, then obviously the photon will miss the mirror!

Is the light track independent of the moving clock for the outside observer, is what I mean. That is, when the moving clock accelerates, the light will miss the mirror, as you said.

Does it mean, now the photon would continue straight in the slant path missing the mirror? Or it's path is also affected as observed by the outside observer, due to acceleration of the moving light clock, which I think shouldn't?

 

[Bill_K]

Does it mean, now the photon would continue straight in the slant path missing the mirror? Or it's path is also affected as observed by the outside observer, due to acceleration of the moving light clock, which I think shouldn't?

Once it's launched, the photon continues in a straight path in the same direction it started, and the outside observer would see it miss the mirror. Even though the clock gets accelerated, along with the mirrors, the photon just continues on its way.

 

[phyti]

Assume the photon misses mirror.
Replace mirror with a one that extends from front to back on ceiling of moving spaceship. Now we can measure our speed relative to light by amount of deviation from vertical.

Is this possible?

 

[Bill_K]

Assume the photon misses mirror.
Replace mirror with a one that extends from front to back on ceiling of moving spaceship. Now we can measure our speed relative to light by amount of deviation from vertical.

No, this only measures our change in velocity.

You know, this depends in no way on Special Relativity. If you and I ride a streetcar, and sit across the aisle and throw a ball back and forth, if the streetcar suddenly speeds up the ball will miss you.

 

[jstephens716]

this is all based on a vertical clock... what if it was horizontal (parallel with trajectory)? Does the whole experiment fall apart or will there still be time dilation? In other words, is time dilation just another way of saying, "we can't measure time with light while it's moving."

 

[Dale]

In a parallel light clock you get both time dilation and length contraction.

 

[jstephens716]

I was under the impression that time dilation was a result of the "hypotenuse" created by the bouncing vertical light while in motion. If the clock is horizontal, we don't get that effect. Is it just a flawed analogy for the theory?

 

[Dale]

Time dilation is easiest to show for such a clock, but the principle of relativity ensures that all clocks show time dilation, regardless of their mechanism.

 

[ghwellsjr]

I was under the impression that time dilation was a result of the "hypotenuse" created by the bouncing vertical light while in motion. If the clock is horizontal, we don't get that effect. Is it just a flawed analogy for the theory?

As DaleSpam said, the vertical light clock is easiest to show on a pair of diagrams such as these from the wikipedia article on Time Dilation. First the one for the stationary light clock:

And then the one for the moving light clock:

However the horizontal light clock can also be shown easily on a pair of spacetime diagrams. First the one for the stationary light clock:

Now this diagram may look more like the previous diagram for the moving vertical light clock but it is for the stationary horizontal light clock. The two thick lines are the two mirrors. The photon starts at the bottom leaving the blue mirror and moving at c (1 foot per nanosecond) toward the red mirror which is five feet away so it takes 5 nsecs as shown going up the vertical axis. At 5 nsecs it reflects off the red mirror and heads back toward the blue mirror at c taking another 5 nsecs so the total time is 10 nsecs for the photon to make the round trip.

Now the diagram for the case where the light clock is moving to the right at 60% of the speed of light:

You can tell that the mirrors are moving at 60%c because, for example, in 10 nsec the blue mirror has moved to the right 6 feet. But because of that, the photon that leaves at the bottom takes longer to reach the red mirror but not as long as it would have taken if it weren't for length contraction which shortens the distance between the two mirrors from 5 feet to 4 feet. You can see this by looking at the Coordinate Time of 10 nsec where the blue mirror is at 6 feet and the red mirror is at 10 feet.

But after the reflection, the photon takes only 2.5 nsecs to get back to the blue mirror because it is moving toward the photon making the total time 12.5 nsecs for the round trip.

So in the stationary case, the light clock took 10 nsecs to make one cycle of the photon but in the moving case it took 12.5 nsecs, illustrating the time dilation for the horizontal light clock.

 

[phyti]

No, this only measures our change in velocity.

You know, this depends in no way on Special Relativity. If you and I ride a streetcar, and sit across the aisle and throw a ball back and forth, if the streetcar suddenly speeds up the ball will miss you.

If a light clock emits a single photon that reflects in a mirror located vertically above the emitter/detector, while in a rest frame, will it still work if it is moving at a constant speed past this same frame?
If yes, how does the photon adjust to a different angle?
If no, does the angle have to be set for a change in speed?

 

[WannabeNewton]

If a light clock emits a single photon that reflects in a mirror located vertically above the emitter/detector, while in a rest frame, will it still work if it is moving at a constant speed past this same frame?

If the photon emerges from one mirror and bounces off the other mirror in the rest frame of the light clock then it must do so in all frames. If this constraint is not imposed then all bets are off. In a given frame we could instead arrange for the photon to miss the opposite mirror by emitting it straight up at the left edge of the bottom mirror and having the light clock move sufficiently fast to the right but if it misses it in this frame then it must miss it in all frames-in the rest frame of the light clock the path of the photon will now be angled to the left. This constitutes a different constraint from the original one.

There's seriously nothing mysterious about this. Just use variations of Bill's example with the ball.

If yes, how does the photon adjust to a different angle?

The photon doesn't need to adjust anything-the only thing the photon cares about is its path through space-time which is the absolute geometric characterization of its trajectory. The coordinate dependent spatial path of the photon is not at all frame-invariant, and changes from frame to frame in accordance with the frame-invariant constraint we've set that the photon must emerge from one mirror and reflect off the opposite mirror composing the light clock. This constraint must be met in all frames and so the spatial path of the photon changes from frame to frame in order to hold true to the constraint.

 

[jstephens716]

As DaleSpam said, the vertical light clock is easiest to show on a pair of diagrams such as these from the wikipedia article on Time Dilation. First the one for the stationary light clock:

And then the one for the moving light clock:

However the horizontal light clock can also be shown easily on a pair of spacetime diagrams. First the one for the stationary light clock:

Now this diagram may look more like the previous diagram for the moving vertical light clock but it is for the stationary horizontal light clock. The two thick lines are the two mirrors. The photon starts at the bottom leaving the blue mirror and moving at c (1 foot per nanosecond) toward the red mirror which is five feet away so it takes 5 nsecs as shown going up the vertical axis. At 5 nsecs it reflects off the red mirror and heads back toward the blue mirror at c taking another 5 nsecs so the total time is 10 nsecs for the photon to make the round trip.

Now the diagram for the case where the light clock is moving to the right at 60% of the speed of light:

You can tell that the mirrors are moving at 60%c because, for example, in 10 nsec the blue mirror has moved to the right 6 feet. But because of that, the photon that leaves at the bottom takes longer to reach the red mirror but not as long as it would have taken if it weren't for length contraction which shortens the distance between the two mirrors from 5 feet to 4 feet. You can see this by looking at the Coordinate Time of 10 nsec where the blue mirror is at 6 feet and the red mirror is at 10 feet.

But after the reflection, the photon takes only 2.5 nsecs to get back to the blue mirror because it is moving toward the photon making the total time 12.5 nsecs for the round trip.

So in the stationary case, the light clock took 10 nsecs to make one cycle of the photon but in the moving case it took 12.5 nsecs, illustrating the time dilation for the horizontal light clock.

Well, this is not exactly a parallel clock, right? They've changed the way the clock operates. This kind of illustrates that it wouldn't be possible with a parallel clock where the light reflects between only two points, a & B. They're version of a parallel clock operates by bouncing the light off three different points... I just don't think it translates, or maybe I missed something.

 

[Dale]

It is a parallel light clock. Note that the vertical axis is time, not space.

 

[ghwellsjr]

Well, this is not exactly a parallel clock, right? They've changed the way the clock operates. This kind of illustrates that it wouldn't be possible with a parallel clock where the light reflects between only two points, a & B. They're version of a parallel clock operates by bouncing the light off three different points... I just don't think it translates, or maybe I missed something.

I think you missed something. Or maybe I don't understand your concern. If you are talking about this diagram:

...it might look like the light is bouncing off of three different points, but A and C are the same mirror, just shown at two different positions in time. Actually, it would have been better to show the top mirror in three places side by side and the bottom mirror in three places side by side where each pair of mirrors above and below represent both mirrors in three different places at three different times. So at all times, wherever the photon is, there is a mirror above and a mirror below.

Does that make sense to you? Or did I misunderstand your concern?

 

[jstephens716]

Just curious, how can this be demonstrated on a clock that doesn't tick with light?

And... say you have two synchronized clocks, send one whizzing past the other in space. According to relativity, they will each perceive the other's clock to run slow, right? So what happens when you compare the times of these two clocks? They'll be the same, won't they? Clock A can't register slower than Clock B if Clock B registers slower than clock A.

I think the problem with light in motion is that, by representing light speed as x=t, there will be tiny instants in time during which things aren't actually where they appear to be in physical space... the light refracting off of those objects will pass through your reference frame according to the given equations, but it's not where the objects actually are at that point in time.

I can't digest the fact that everything is relative in this model, except light. If you think of light, one photon at a time moving through a giant 3D grid, it has to be relative... it can't be in two places at once, and we know it doesn't form an instantaneous bridge between it's source and the observer.

 

[ghwellsjr]

Just curious, how can this be demonstrated on a clock that doesn't tick with light?

Easy. Radioactive particles have a built-in clock not based on light. After a period of time, most of them disintegrate into something else. So if they are stationary, we can measure how long it takes for most of them to disintegrate. However, if they are in motion, it takes longer for most of them to disintegrate. In fact this was one of the first "proofs" of Special Relativity regarding high speed muons created in the upper atmosphere by cosmic rays getting all the way down to the surface of the Earth before disintegrating which they could not do if their built-in clock wasn't running slower than when at rest.

And... say you have two synchronized clocks, send one whizzing past the other in space. According to relativity, they will each perceive the other's clock to run slow, right?

Well, let's give it a try with the two horizontal light clocks I diagrammed for you in post #14, except I will now show them with two "ticks" instead of just one. Here's the light clock moving at 0.6c to the right:

And here's the stationary one, except that I'm having its second mirror on the left side so that it won't conflict with the moving light clock and I'm showing its two mirrors in black and green so we can easily tell them apart:

Now I show them together in the same diagram. Notice how I "synchronized" them at the start like you requested but note that they don't stay synchronized since one of them is moving:

Now we want to show how they perceive each other. So I'll simply allow the photon marking the first tick on each clock to propagate toward the other clock:

As you can see, the photons hit the other clock coincident with their second tick. This means that each clock will perceive the other clock as running slow by a factor of 50%. We could continue the drawing out to include more ticks and the same thing would continue to happen.

So what happens when you compare the times of these two clocks? They'll be the same, won't they? Clock A can't register slower than Clock B if Clock B registers slower than clock A.

Do you still think so?

I have shown all these diagrams so that the green/black clock is at rest and the blue/red clock is moving but I can use the Lorentz Transformation process to see the same situation in a diagram in which the blue/red clock is at rest:

Or I can transform to another diagram in which both clocks are traveling at the same speed 33.33%c in opposite directions. Now their clocks stay in "sync":

I think the problem with light in motion is that, by representing light speed as x=t, there will be tiny instants in time during which things aren't actually where they appear to be in physical space... the light refracting off of those objects will pass through your reference frame according to the given equations, but it's not where the objects actually are at that point in time.

It's not a good idea to think of objects "actually" being at some point at some time because it all depends on the reference frame you choose to use. As I have just shown, you can transform from one frame to another and all the coordinates change both in location and in time but whatever any observer perceives remains the same.

I can't digest the fact that everything is relative in this model, except light. If you think of light, one photon at a time moving through a giant 3D grid, it has to be relative... it can't be in two places at once, and we know it doesn't form an instantaneous bridge between it's source and the observer.

You're exactly right, it can't be in two places at once but we can call the place and the time it is there by two different sets of coordinates, can't we? It's no different than having two different scales or coordinates for temperature and a set of formulas to convert between them. We can say that my temperature is 98.6 degrees Fahrenheit or 37 degrees Centigrade and no one gets upset. But if I say that those two photons crossed paths in one coordinate system at 5 feet and at 15 nanoseconds and in another system at -5 feet and at 15 nanosecond and in a third system at 0 feet and at 14.1 nanoseconds, why should that be upsetting?

 

[jstephens716]

Woah, thanks for the thorough response. That wasn't enough thanks... Thank you thank you thank you.

As for the clock... I meant something measurable with more confidence. I noticed the wording, "After a period of time, most of them disintegrate into something else... However, if they are in motion, it takes longer for most of them to disintegrate."

Ok... so most of them take longer, but some don't? Would you say some of them have a slower atomic clock than others?

If so, most of them would disintegrate during the time it takes light to reach Earth from wherever these rays originated, and some would not... regardless of motion.

The temperature analogy... this is kind of what I was getting at with the relativity of light to time & distance. Fahrenheit can be expressed in terms of Centigrade while Speed of Light can be expressed in terms of a Snail's Pace (assuming the snail always moved at the same pace). But the upsetting part is that we would need to add some sort of ambient constant wherein heat could travel from one reference frame to another without losing any energy (to know how hot our heat is we, must be able to compare it to something standard at all times). So this ambient constant "feels" warmer or colder depending on the temperature of the reference frame.

That's the way I view the model based on light speed, especially a light speed that is expressed as x=ct reborn as x=t via the transformations (a.k.a making Light the ultimate authority in how we perceive time and space). It just seems sort of self-centered to assume that things only happen the instant that light reveals an event to the observer... that's all.

p.s. I really appreciate the conversation, simply fascinating. Probably feels like teaching physics to a monkey for most of you.

 

[ghwellsjr]

Woah, thanks for the thorough response. That wasn't enough thanks... Thank you thank you thank you.

You're welcome, welcome, welcome!

As for the clock... I meant something measurable with more confidence. I noticed the wording, "After a period of time, most of them disintegrate into something else... However, if they are in motion, it takes longer for most of them to disintegrate."

Ok... so most of them take longer, but some don't? Would you say some of them have a slower atomic clock than others?

If so, most of them would disintegrate during the time it takes light to reach Earth from wherever these rays originated, and some would not... regardless of motion.

Radioactivity is a probability function. We can't determine anything from anyone radioactive particle but we can from a very large number of them. If we consider the half-life of a muon to be 2 microseconds, then if we had a very large number of them, half of them would disintegrate every 2 microseconds so after 20 microseconds, less than 0.1% of them would be left. At 99% the speed of light, more than 0.1% of them would survive after 140 microseconds. The difference is very easy to observe even if we can't predict exactly when anyone muon will disintegrate.

The temperature analogy... this is kind of what I was getting at with the relativity of light to time & distance. Fahrenheit can be expressed in terms of Centigrade while Speed of Light can be expressed in terms of a Snail's Pace (assuming the snail always moved at the same pace). But the upsetting part is that we would need to add some sort of ambient constant wherein heat could travel from one reference frame to another without losing any energy (to know how hot our heat is we, must be able to compare it to something standard at all times). So this ambient constant "feels" warmer or colder depending on the temperature of the reference frame.

Please note that I said "whatever any observer perceives remains the same" no matter what reference frame you use. This goes for temperature as well. Don't think of heat or anything else traveling from one reference frame to another. Use only one reference frame to specify, analyze and describe everything in a given scenario. Then you can transform all the coordinates (both time and distance) of all the events into a new frame.

What you are doing is like saying that the temperature at one end of a rod is 98.6 degrees Fahrenheit and the other end is 37 degrees Centigrade so there will be a heat flow between the two ends. If you use the same coordinate system throughout then there won't be any difference in the physics involved.

That's the way I view the model based on light speed, especially a light speed that is expressed as x=ct reborn as x=t via the transformations (a.k.a making Light the ultimate authority in how we perceive time and space). It just seems sort of self-centered to assume that things only happen the instant that light reveals an event to the observer... that's all.

Well we certainly can't deny that something did happen the instant that light reveals an event to an observer and that's the important thing. We can't have a theory where that is violated, can we? And the point is that even though it doesn't seem obvious or even like it will work, we can say that the speed of light is the ultimate authority for defining our coordinates for space and time and it results in a simple theory. There is no other theory that is simpler even though there are others that also work.

p.s. I really appreciate the conversation, simply fascinating. Probably feels like teaching physics to a monkey for most of you.

I would not want to teach a monkey anything and I think we all used to feel like monkeys when we first learned Special Relativity. I still feel like a monkey when it comes to General Relativity.

 

[jstephens716]

This is where I am now... There is a giant cartoon bullet headed directly for Kevin Bacon's face and someone is watching from a safe distance (all in space). To amplify my point, we could even say that the Observer is traveling away from this event at an incredible speed, watching in the rear-view mirror

I'm going to consider (and so would Kevin) that when the bullet strikes him, that particular moment actually happened. Both the bullet and his face would agree. However, the Observer see's Kevin's smirking face for four more grueling seconds (or longer) before he/she realizes Kevin was hit.

Now, for those four seconds, the Observer perceives Kevin as smirking but, I assure you, he was not.

Is the Observer in the past, is Kevin in the future, or are we just tracking photons?

Again, I may have missed the point. And thanks for any insight.

 

[Dale]

Relativity is what remains after accounting for the finite speed of light. None of the standard relativistic effects (length contraction, time dilation, relativity of simultaneity) are optical illusions. They are what remain after an intelligent observer accounts for any optical delay.

For instance, if I receive a signal from near the sun at 9:54 according to my watch, then I account for the 8 minute delay in light propagation and say that the signal was emitted at 9:46 in my frame.

Similarly, a person 4 light-seconds from poor Kevin recognizes that he was shot 4 seconds ago in his frame once he receives the signal.

People doing relativity are not simply tricked into believing in optical illusions. They carefully account for the propagation of light and find that the universe is different from what you might naively suppose.

 

[ghwellsjr]

This is where I am now... There is a giant cartoon bullet headed directly for Kevin Bacon's face and someone is watching from a safe distance (all in space). To amplify my point, we could even say that the Observer is traveling away from this event at an incredible speed, watching in the rear-view mirror

I'm going to consider (and so would Kevin) that when the bullet strikes him, that particular moment actually happened. Both the bullet and his face would agree.

Everyone agrees that that particular moment actually happened. I'm wondering why you feel the need to emphasize this point. Did I say something that led you to believe that I would think otherwise?

However, the Observer see's Kevin's smirking face for four more grueling seconds (or longer) before he/she realizes Kevin was hit.

Now, for those four seconds, the Observer perceives Kevin as smirking but, I assure you, he was not.

Just like the bullet arriving at Kevin's face is a moment that actually happened, so is the arrival at the Observer's face of the photons carrying the image of that event another moment that actually happened. Likewise the arrival at the Observer's face of the photons carrying the image of the bullet as it is in transit to Kevin's face and all other photons hitting observer faces. The Observer doesn't see Kevin's smirking face with the bullet about to hit it for four seconds.

Is the Observer in the past, is Kevin in the future, or are we just tracking photons?

I'm not sure how to answer that question. When we draw a spacetime diagram, we are showing the progress through time of each observer/object. You can imagine the scenario unfolding by starting at the bottom (the earliest time) and moving upwards (the latest time). If you transform to a different frame, the Coordinates for both Time and Space change but all the actual happenings remain the same, including the times on each observer/object's clocks of when things actually happened. Maybe if I draw some spacetime diagrams for you scenario, it will make more sense.

Again, I may have missed the point. And thanks for any insight.

View attachment 67062

You didn't describe too many details in your scenario so I have taken the liberty to fill them in. We start with the rest frame of Kevin and the Observer on his left side. Shortly after the Observer sees Kevin, he fires the bullet that will eventually hit him. We will assume that the Bullet has a clock, as well as Kevin and the Observer, and they each can see their own clock and both of the other ones. In these diagrams, Kevin is shown as the thick blue line, the Observer as the thick red line and the Bullet as the thick black line. The dots represent one-second increments of time for each clock. If the clock is moving, the dots will be stretched out compared to the Coordinate Time. The thin lines represent photons carrying the images of the various Observers/objects and their clocks to the other Observers/objects:

What I want you to notice is that during the last four seconds of Coordinate Time, the Observer is seeing his own clock tick through three seconds, the Bullet's clock tick through two seconds, and Kevin's clock tick through about 1.5 seconds. Prior to that, the Observer sees Kefin pass him when his own clock was at about 2.5 seconds and Kevn's clock was at about 4 seconds. And before that, the Observer saw that Kevin's clock was ticking more than twice as fast a his own. These are all actual happenings, wouldn't you say?

Now let's transform to the Observer's rest frame:

Go back to the description of all the "actual happenings" for the previous diagram and confirm that the exact same description applies to this frame even though all the Coordinate Time and Space values are different. Can you see that?

Finally, let's go to the Bullet's rest frame:

By now, you should be seeing that all frames depict the same information, they just have different Coordinates. Any questions?

 

[jstephens716]

The point is... the Kevin diagram is just another mirror clock (figuratively speaking) that begins when Kevin gets hit in the face, only it's set to count different time intervals (and, so far, it's only half of the cycle). One problem with SR is that it assumes light won't conform to uniform motion, yet it uses light in uniform motion to illustrate the effects of time dilation with a mirror clock (i.e. that type of clock only exists on a graph). What, I believe, it actually illustrates is that you CAN move in relation to the speed of light, that C is not equal to C in all inertial frames of reference. Furthermore, the coordinates of an event (and it's path of trajectory) in any reference frame will always remain the same to all observers, no matter what (you only experience "motion" when you move out of this reference frame - absolute time passes, it won't wait on anything). Space won't contract and time dilation won't occur... what WILL happen is that everyone will agree on light speed and nobody will agree on time. If everyone assumes their own c' then we can all agree on time again. A quick snapshot of assumptions... (http://en.wikipedia.org/wiki/Galilean_invariance)

Some of the assumptions and properties of Newton's theory are:

The existence of infinitely many inertial frames.

Each frame is of infinite size (covers the entire universe).

Any two frames are in relative uniform motion.

The inertial frames move in all possible relative uniform motion.

There is a universal, or absolute, time.

Two inertial frames are related by a Galilean transformation.

In all inertial frames, Newton's laws, and gravity, hold.
In comparison, the corresponding statements from special relativity are same as the Newtonian assumption. Rather than allowing all relative uniform motion, the relative velocity between two inertial frames is bounded above by the speed of light.

Instead of universal time, each inertial frame has its own time.

The Galilean transformations are replaced by Lorentz transformations.

In all inertial frames, all laws of physics are the same.
So, do the math according to the laws of nature and you get an absolute universe... but do it according to a constant speed of light and you will get a "light universe" where time waits on light to catch up.

I don't doubt that processes may slow down (relative to absolute time) when in motion. It makes perfect sense. We know that atoms have a lot of "empty space" in them... so you go whipping them around and, yeah, you might measure some sort of disturbance. Also, I have to go back and mention this... the half life of radioactive particles. "We can't determine anything from anyone radioactive particle." Ok, but we can tell when we have half of what we started with. This doesn't really give us predictive power over how long a particle will resist disintegration... it marks a specific point in absolute time when, by chance, there are only half of what we started with.

I conclude that there are way too many assumptions to put this all on a graph and call it complete... but that's just my reference frame ;)

 

[dauto]

jstephens716, it seems you now understand fairly well the concepts but still remain sceptical (Nothing wrong with that. A healthy dose of skepticism is an essential element of science). Would the fact that the relativity of time has been actually measured using atomic clocks sway your opinion? Would the fact that the relativity of time must be taken into account for the proper operation of devices such as the GPS that you might have in your pocket right now sway your opinion? Would the fact that the relativity of time is an essential element of a much broader theory - relativity, and that theory has been confirmed in uncountable experiments and no experiment has ever shown it incorrect sway your opinion?

 

[Dale]

Note that it is not part of the mission of PF to convince skeptics about SR. The evidence supporting SR is overwhelming and at this point skeptics can only remain skeptics by ignoring the experimental data:
http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

It is also not part of the mission of PF to advance the state of the art in science. That is not to say that we believe that there will never be a next theory following SR. Rather, we believe finding that next theory is best done through the established professional scientific process instead of an internet forum.

The mission of PF is to educate. We help students and other interested people learn about relativity as it is understood and used by modern professional scientists. This isn't an opportunity for debate, it is an opportunity for learning.