Is relativity science?

[ribuck]

Did Einstein confuse the movement of light with time?  Isn't a precision clock a light clock?

 

No, and no.

 

... if you were to go into space and just fly in circles at 90% the speed of light for two years... How many times would the earth go around the sun? 

 

 I'm not prepared to work through the maths in a forum, but the equations can be found here. The example they use is for a spaceship moving at 80% of the speed of light and travelling from the earth to a star 4 light-years away then returning to earth. Upon return, ten years have passed on earth, but only six years have passed aboard the spaceship, and indeed the people on the spaceship will only have aged six years.

[Pepin]

Okay... See... One of the problems I have, and where I really get confused, is... Did Einstein confuse the movement of light with time?  Isn't a precision clock a light clock?  I believe light speed, is a constant, for light, so if you move a light clock it will slow down... 

 

Saying the speed of light is constant in all reference frames is a little difficult to get the implications of. Essentially, no matter your velocity, you will always measure the speed of light to be the same. If I measure that you are moving at 80% of the speed of light and both you and I measure the light that you are emitting, we will both measure the speed of light.

 

Classically, what we'd expect is that you'd measure a lesser number than I would, just like if you were to shoot a gun off the front of a moving train. In that scenario, to you the bullet would be traveling at lets say 1000mph. If I was outside the train and stationary and lets say the train is moving at 1000mph, I'd measure the bullet's velocity to be 2000mph. But if this was Einsteinian bullet, this doesn't happen, instead I'd measure the bullet to be at X MPH and you'd measure the bullet to be the same.

 

A great thought experiment that Einstein came up with is to imagine that you are on a hover board with a light beam bouncing up and down between two plates. You are moving in a direction that is perpendicular to the two plates at 1/8 the speed of light. We know for a fact that you will measure the light to be moving at speed C (the speed of light). Now, if I am observing you from an outside perspective, we know for a fact that I won't measure the vertical up and down component of the light to be C because you are moving to the right. Instead I'd measure the diagonal motion to be C, which means if I were to measure the light beams vertical components, they would be moving slower. Not just that, but you would be moving slower as well. To get a good visual demonstration of this, I suggest watching this video at the 6:45 mark

 

I'm certain that I'm just repeating what others have already said, but this is a difficult idea to wrap your head around and to really understand. It took me a few months to be comfortable and capable of explaining it.

[ribuck]

.. this is a difficult idea to wrap your head around ... It took me a few months to be comfortable ...

 

It took me a few years.

 

Most of the time, when we learn something new we just need to add some more knowledge to what we already know. In the cases of relativity and quantum mechanics, however, we first need to let go of many assumptions which pervade our daily lives but which do not generalize to all situations.

[Hannibal]

Okay... See... One of the problems I have, and where I really get confused, is... Did Einstein confuse the movement of light with time?  Isn't a precision clock a light clock?  I believe light speed, is a constant, for light, so if you move a light clock it will slow down...

 

No. To put it simply, if one guy sat on a train with his light clock measures a second each time the light pulse bounces up and back down again, then a guy on the platform watching as he train passed by would see the same clock ticking, but the light would be taking a zig-zag path instead of just up and down.

 

As both men measure the speed of the light pulse to be the same constant value, and the man on the platform sees the light taking a longer (zig-zag) path, then the man on the platform must see the clock tick slower. 

 

So... if the light pulse travelled the same distance (obviously it can't travel two different paths simultaneously) & both men measured the same speed, then as speed is distance divided by time and we know that the speed and distance were the same, then the time must have been different according to each man. The man on the train sees the man on the platform's time passing more slowly, and the man on the platform sees the man on the train's time passing more slowly.

 

 

 

On the other hand, if you were to go into space and just fly in circles at 90% the speed of light for two years... How many times would the earth go around the sun? 

 

 

Lets say 0.866 times the speed of light because it comes out at a nice 50% ratio.  In that case you'd see the sun go round twice as fast as normal, and when you land back on Earth you'd say "Holy cow! did you see that? The sun was going round twice as fast as normal!". And your pals would look at you like you're nuts and say "Um... no. You were gone 4 years and the sun went round 4 times. By the way - while you were gone I spied through your spaceship window with my telescope. Why were you brushing your teeth in slow motion?".

[LifeIsBrief]

Maybe it's just me... but, if I saw the earth spinning around, and travelling around the sun at double speed... I'd say "Oh, my clock wrong".  I would then adjust the clock so that 1 day, is one rotation of the earth.  If I didn't... Have we proven that organic matter moves through time, the same way light does? Meaning, isn't it entirely possible, that moving at double speed through time, requires more calories, and water?

 

Have we proven that you wouldn't die of thirst in one day, instead of two, simply by misinterpreting your movement through time?

[ribuck]

Yes we have.

[Hannibal]

Maybe it's just me... but, if I saw the earth spinning around, and travelling around the sun at double speed... I'd say "Oh, my clock wrong".  I would then adjust the clock so that 1 day, is one rotation of the earth.  If I didn't... Have we proven that organic matter moves through time, the same way light does? Meaning, isn't it entirely possible, that moving at double speed through time, requires more calories, and water?

 

Have we proven that you wouldn't die of thirst in one day, instead of two, simply by misinterpreting your movement through time?

 

The GPS system we've already mentioned is just a series of orbiting clocks. They aren't light clocks - the relativistic effects aren't just optical effects.

 

Regarding moving at double speed through time (i.e. compared to someone else's time flow) -  yes, of course you would use twice the calories, etc.

[RestoringGuy]

Lets say 0.866 times the speed of light because it comes out at a nice 50% ratio.  In that case you'd see the sun go round twice as fast as normal, and when you land back on Earth you'd say "Holy cow! did you see that? The sun was going round twice as fast as normal!". And your pals would look at you like you're nuts and say "Um... no. You were gone 4 years and the sun went round 4 times. By the way - while you were gone I spied through your spaceship window with my telescope. Why were you brushing your teeth in slow motion?".

I know you're essentially right, but that oversimplification can confuse people.  Please consider maybe this can clarify some of the misconceptions some other people have (I used to have this misconception).  As you move away from Earth, we both see the other go slow on the way out.  The velocity is relative and both are moving away from each other (who really "is moving"?).  Then on the return trip we both see each other go fast (light waves pile up doppler-style).  The situation is symmetric during all of the uniform motion.  I always wondered why, if the situation is symmetric, why does only one side "lose time"?!?  Relativity should be bogus because the traveller sees the earth move away and back in the same fashion.

 

The answer I have learned is that the space traveller is the only one who changes inertial frames (and it's much like changing gravitational frames).   So you not only have to travel at 0.866c to witness a mismatch, but only one side, the traveller, must shift from one uniform motion to another (or do so in a series of thrusts,etc.).  Only then can the inequality in clocks be measured as real, seen as more than just an observational quirk. Without shift in frames both sides can just say the other is equally "slow".  The flight of aircraft around the world does this inertial dance by changing its vector of motion little by little as it follows the curvature of the earth.  That's why the aircraft "loses" a small bit of time compared to the stationary clock, not just because the plane is moving.  If you could hold the plane still and fly the earth around it, the opposite should happen, because earth would be experiencing the centripetal forces needed to vary its frame.  Things like the "twin paradox" do not work if neither (or both) twins change their frame in a symmetric way.  This used to confuse me, but now I know it's not just the speed that causes measurable relativistic time dilation.  It's the change in inertial frame that matters.

[ribuck]

... Please consider maybe this can clarify some of the misconceptions some other people have (I used to have this misconception).  As you move away from Earth, we both see the other go slow on the way out.  The velocity is relative and both are moving away from each other (who really "is moving"?).  Then on the return trip we both see each other go fast (light waves pile up doppler-style).  The situation is symmetric during all of the uniform motion.  I always wondered why, if the situation is symmetric, why does only one side "lose time"?!?  Relativity should be bogus because the traveller sees the earth move away and back in the same fashion.

 

You can understand this situation without needing to consider inertial frames at all. Your example is only symmetric during the outward journey.

 

Consider what happens when the outgoing craft reverses direction at the far end of its journey. Immediately this craft sees the light waves from earth piling up "doppler-style", and sees things happening faster on earth.

 

But it's not symmetrical for the guy on earth: he doesn't see the change yet. He doesn't see it until he receives light waves that came from the spacecraft after it reversed direction! So the earthbound observer sees the spacecraft guy moving slowly for more than half of his elapsed time, which nicely accounts for the space traveller arriving back to earth younger than his twin that he left behind.

 

From a mathematical point of view it's easier to work with the inertial frames of reference rather than with the doppler shifts, but the overall result is (necessarily) identical.

 

I wish someone had explained this to me when I first learned relativity at high school, as I find it much easier to interalise this way.

[pretzelogik]

Does the fact that the earth is hurtling around the sun at 67,360MPH have an impact on the relativistic effects of space travel?

[Hannibal]

Does the fact that the earth is hurtling around the sun at 67,360MPH have an impact on the relativistic effects of space travel?

 

It's all relative. So when a shuttle for example goes into orbit, it is also hurtling around the sun at 67,360 mph, give or take. There is no absolute frame of reference, so if we're measuring differences between earth and shuttle, from the perspective of either, then motion relative to something else, such as the sun or any other thing, is of no concern.

[Hannibal]

I know you're essentially right, but that oversimplification can confuse people.  Please consider maybe this can clarify some of the misconceptions some other people have (I used to have this misconception).  As you move away from Earth, we both see the other go slow on the way out.  The velocity is relative and both are moving away from each other (who really "is moving"?).  Then on the return trip we both see each other go fast (light waves pile up doppler-style).  The situation is symmetric during all of the uniform motion.  I always wondered why, if the situation is symmetric, why does only one side "lose time"?!?  Relativity should be bogus because the traveller sees the earth move away and back in the same fashion.

 

The answer I have learned is that the space traveller is the only one who changes inertial frames (and it's much like changing gravitational frames).   So you not only have to travel at 0.866c to witness a mismatch, but only one side, the traveller, must shift from one uniform motion to another (or do so in a series of thrusts,etc.).  Only then can the inequality in clocks be measured as real, seen as more than just an observational quirk. Without shift in frames both sides can just say the other is equally "slow".  The flight of aircraft around the world does this inertial dance by changing its vector of motion little by little as it follows the curvature of the earth.  That's why the aircraft "loses" a small bit of time compared to the stationary clock, not just because the plane is moving.  If you could hold the plane still and fly the earth around it, the opposite should happen, because earth would be experiencing the centripetal forces needed to vary its frame.  Things like the "twin paradox" do not work if neither (or both) twins change their frame in a symmetric way.  This used to confuse me, but now I know it's not just the speed that causes measurable relativistic time dilation.  It's the change in inertial frame that matters.

 

I would encourage people to ignore things like doppler shift, because that IS just an optical effect as the OP alluded to (although i'll admit that it's kindof complicated, as the speed of light being the universal speed limit makes it a 'speed limit of reality'). Also, in reality your view (optically speaking) of the situation would be pretty much wiped out by red/blue-shift, Tyrell effect/tunelling, etc.

 

So I have to disagree strongly with this:

 

 

Only then can the inequality in clocks be measured as real, seen as more than just an observational quirk

 

 

Those relativistic time dilation effects, without any kind of acceleration being considered at all, ARE REAL. They aren't 'observational quirks'. The 4d geometry of space-time means that the passage of time really is different for both frames of reference with regards to each other. It's not just some kind of illusion.

 

 

 

The solution to the twin paradox (I'm talking to an audience in general now) lies in the fact that the turnaround in the journey falls outside of the bounds of 'special' relativity, as you already pointed out. The best way to understand this (for me at least) is to look at a spacetime diagram of the journey, and to chart the simultaneity of events between the earth twin and spaceship twin (see 'relativity of simultaneity' for anyone to which this is a new concept). 

 

Lets suppose, for simplicity, that our model starts with the spaceship twin passing right by earth at full speed already, and ends passing by at full speed in the opposite direction, right by the earth again. SOMEHOW we can synchronize their clocks at the start, and somehow we can compare them at the "end" (some calculated time that makes both observers agree on when that actually occurs).

 

 

Looking at the chart, you can see:

Taken from the perspective of the spaceship twin, he'll see the earth disappearing into the distance, spinning at 50% of normal. When the spaceship begins to decelerate at the half-way point, that twin will see the earth as being "in the past" (clocks behind, even when you factor in the time for light to travel from clock to distant eye) and it's passage of time beginning to increase. By the  time the spaceship has accelerated back up to full speed in the opposite direction, the earth is now "in the future" because while turning around it's passage of time increased dramatically (relative to the spaceship's - so the same as the spaceships slowing down a lot ), until now it's settled back to 50% as the spaceship's acceleration has fallen back to zero. 

 

Now the earth is "in the future" by quite a lot, but it's time is flowing more slowly relatively to the spaceship, again, so that when the spaceship twin gets back to the start the earth is now %50 "in the future", relative to the travelling twin's time spent flying.

 

 

From the earthbound perspective, the other twin simply sees the spaceship zoom off with the astronaut ageing at 50%, and zoom back again ageing at %50.  When they both "meet" at the end, both agree that the spaceship twin is younger.

 

The diagram below shows the journey with an instantaneous turnaround, and the simultaneity gap shown is what I was referring to by the earths time rapidly speeding up during turnaround (i would assume that it's actually the acceleration forces causing the spaceships time to run very slowly - the relative effect is the same):

 

[Phillip Brix]

I apologize ahead of time for not reading the whole topic.

I’ve also never really understood the theory of relativity.

here's my problem. let's say we have an observer, an object going 60% of the speed of light relative to the observer, and the observer is emitting a light beam. in order for the theory of relativity to be true, from the perspective of the light beam itself both objects must essentially be going zero. Anything other than zero for the 60% light object, would mean that the 60% light object would see the light beam going slower than normal.

 

I agree light is constant-in the medium under which it it traveling. If its traveling in the air its going one speed. if its traveling in a vacuum its going another.

Here's the problem. Imagine you're in an airplane going 60% of the speed of light. You fire a light beam.

now I’m fairly confidant that while its in the plane it will go the speed of light, because you're carrying your medium with you.

however, does it go the speed of light relative to you after it exits the plane? If it does, then the speed of light is not constant in air. If it doesn't then the speed of light is constant in air, but the theory of relativity needs to be rethought.

 

also I’m highly skeptical of the Michel Morley experiment. i don't understand why it failed. The earth is not just traveling through space, Its accelerating, that is changing velocity - both direction and speed -  while doing so. So I don’t see how the speed of light cannot change under such a circumstance, as I’m pretty sure the velocity of light should change under an accelerating frame of reference, even according to Einsteins theory.

The only way I personally can make any sense of it is if gravity isn't a force accelerating matter but as yet something else we haven't discovered.

[Hannibal]

Glad to see that you're better versed in physics than Einstein and all that came after him

 

 

here's my problem. let's say we have an observer, an object going 60% of the speed of light relative to the observer, and the observer is emitting a light beam. in order for the theory of relativity to be true, from the perspective of the light beam itself both objects must essentially be going zero. Anything other than zero for the 60% light object, would mean that the 60% light object would see the light beam going slower than normal.

 

 

Photons move, in a vacuum, at C (maximum possible speed of anything). As such, they don't experience time - at 100% C the passage of time drops to zero. Therefore, from a photon's perspective, it is everywhere at the same time. It is timeless. Your scenario doesn't make sense in that context, as from a photon's perspective, it isn't moving.

 

 

I agree light is constant-in the medium under which it it traveling. If its traveling in the air its going one speed. if its traveling in a vacuum its going another.

Here's the problem. Imagine you're in an airplane going 60% of the speed of light. You fire a light beam.

now I’m fairly confidant that while its in the plane it will go the speed of light, because you're carrying your medium with you.

however, does it go the speed of light relative to you after it exits the plane? If it does, then the speed of light is not constant in air. If it doesn't then the speed of light is constant in air, but the theory of relativity needs to be rethought.

 

Your logic is all broken because you're choosing arbitrary frames of reference at different points throughout the same thought experiment.  Experiments have proven that light travels at a constant speed (through a constant medium - in this case air ) for every observer, regardless of relative motion.

 

Your mistake is to measure the speed relative to air inside the plane, and then air outside, when the actual observer which the light movement is relative to is the passenger. The air inside the plane is moving zero relative to the passenger, so when you choose to use that frame of reference there is no problem. BUT, when you randomly choose to change the frame of reference half way through to that air outside, then it shouldn't be surprising that it doesn't add up. If the passenger fires the pulse inside the plane, then a stationary man floating on a cloud outside as the plane flies through it at 500mph would measure the pulse at the same speed as the passenger that fired it. How? because speed is distance over time, and as the distance and speed remain the same, then the time must be different. The two men are experiencing a "faster" flow of time relative to the other guy.

 

 

 

also I’m highly skeptical of the Michel Morley experiment. i don't understand why it failed. The earth is not just traveling through space, Its accelerating, that is changing velocity - both direction and speed -  while doing so. So I don’t see how the speed of light cannot change under such a circumstance, as I’m pretty sure the velocity of light should change under an accelerating frame of reference, even according to Einsteins theory.

The only way I personally can make any sense of it is if gravity isn't a force accelerating matter but as yet something else we haven't discovered.

 

How does "I don't see how" equate to the theory being wrong? "I can't see how" is the whole point. "I can't see how" is fixed by supposing that time slows relatively with relatively increasing speed. Experiments verify that it does. 

 

And for the sake of the experiment, there is no indicator that anything is accelerating.  For all we know he experiment is stationary, while the universe moves. The parameters of the experiment don't violate 'special' relativity.

[LifeIsBrief]

Regarding moving at double speed through time (i.e. compared to someone else's time flow) -  yes, of course you would use twice the calories, etc.

 

Different quote:

 

Photons move, in a vacuum, at C (maximum possible speed of anything). As such, they don't experience time - at 100% C the passage of time drops to zero. Therefore, from a photon's perspective, it is everywhere at the same time. It is timeless. Your scenario doesn't make sense in that context, as from a photon's perspective, it isn't moving.

 

I think I'm starting to understand, so I've been trying to remain quiet, but this part really confuses me.  If you will need twice the calories, and water, to move at twice the speed through time, of someone on the planet earth...  Why won't you age?  How is this not the same as having lived the double time?  I still find myself wanting to say "light on your ship is younger, your computers might be, your thoughts may have been slowed by your relativistic movement, a cesium atom might react a certain way, but if you still ate and drank etc... double time... Aren't you going to experience the same effects of age?"

 

If I should pay attention to what I would call the "earth clock" in order to maintain a calorie and water schedule... that seems to suggest that for organic matter there is an objective time, outside of relativity, connected to where we evolved.  It's almost seems as though relativity works from the perspective of a robot.  Does that make any sense whatsoever?

 

Edit: My phrasing here, catches me "for organic matter there is an objective time". I find myself wanting to correct "No, there is a subjective time"... then wanting to say "No, because it is of real consequence for all organic matter, it's not dependent on an individual organic perspective, so it's objective"... Interesting, I'm going to have to dwell on this a bit, maybe it pulls me out of my relativity spiral. 

 

Thank you for all the responses thus far, by the way.

[ribuck]

... this part really confuses me.  If you will need twice the calories, and water, to move at twice the speed through time, of someone on the planet earth...  Why won't you age?  How is this not the same as having lived the double time?

 

I think there's some misunderstanding somewhere. Time dilation affects every physical process. It really is time itself that passes at different rates for the accellerating and non-accellerating twin. If the space-twin comes back from the journey after five of his years, and ten years have passed for the earth-twin, then the earth-twin has definitely consumed twice the calories, and aged twice as much, and his clocks have advanced twice as much, and the radioactive carbon-14 atoms in his body have undergone twice as much exponential decay.

 

Photons move, in a vacuum, at C (maximum possible speed of anything). As such, they don't experience time - at 100% C the passage of time drops to zero. Therefore, from a photon's perspective, it is everywhere at the same time. It is timeless. Your scenario doesn't make sense in that context, as from a photon's perspective, it isn't moving.

 

Yes, that's one of the fascinating things about relativity. It's clear that there really is something fundamentally surreal about the photon. It behaves totally differently from regular matter. I hope that someday there will be a breakthrough insight from this, that leads us to reorganise our understanding of time and space in a way that makes it conceptually simpler (in the same sense that the discovery of the concept of "zero" made it possible to reorganise and simplify the understanding of mathematics).

[RestoringGuy]

Those relativistic time dilation effects, without any kind of acceleration being considered at all, ARE REAL. They aren't 'observational quirks'. The 4d geometry of space-time means that the passage of time really is different for both frames of reference with regards to each other. It's not just some kind of illusion. 

I am meaning "observational" differently than you are.  I do not mean an illusion or trick like doppler.  Your explanation makes perfect sense except this idea about dilation being called real.  Until the traveller turns around, both parties witness the other as slowed down.   What I mean by "not real" is until the traveller turns around, there is no absolute reality to the claim of "who is slowed down" and "who is sped up" by the dilation.  To me, real dilation can be measured without question as to which clock was time-dilated.  Consider if there are two ships, a "faster ship" is not real but only "observational" (by my definition) because there is always a frame where that particular ship is the slower one.  They still have different objective vectors in 4d, but the word "faster" is an observational result decided by the observer's frame.  You will agree I hope that calling one clock "faster" is not real in an absolute sense before the turnaround of spaceship that uniformly leaves Earth (ignoring the GR effect on the Earthbound clock).

 

It seems the objective idea that "time passes at different rates" is totally bogus before the traveller turns around, because in order to be different rates, one rate must be faster and one must be slower.  And how do you evaluate this before the turnaround?   In that sense, time dilation is not real, but only observational --  not in the dopper-sense (where there is absolute meaning to what is faster), but in a new sense that both parties can have apparatus inside their frame and with their own apparatus they can rightly disagree who is slower.  There is no real answer who is in the time-dilated frame.  With your graph you cannot reconcile the ambiguity of who is slowed down until somebody changes their velocity, and you allow people like the twins to meet up in some fashion and compare their clocks.   If we use the word real to apply to time dilation before the turnaround, the graph can be transformed by Lorentz equations and the guy on the ship can say slowed-down time dilation on Earth is also real.  Whatever.  We are in material and equational agreement, just vocabulary disagreement.

[Hannibal]

I am meaning "observational" differently than you are.  I do not mean an illusion or trick like doppler.  Your explanation makes perfect sense except this idea about dilation being called real.  Until the traveller turns around, both parties witness the other as slowed down.   What I mean by "not real" is until the traveller turns around, there is no absolute reality to the claim of "who is slowed down" and "who is sped up" by the dilation.  To me, real dilation can be measured without question as to which clock was time-dilated.  Consider if there are two ships, a "faster ship" is not real but only "observational" (by my definition) because there is always a frame where that particular ship is the slower one.  They still have different objective vectors in 4d, but the word "faster" is an observational result decided by the observer's frame.  You will agree I hope that calling one clock "faster" is not real in an absolute sense before the turnaround of spaceship that uniformly leaves Earth (ignoring the GR effect on the Earthbound clock).

 

 

Gotcha, and agreed. I'm glad we had this exchange because what you just said is a good nugget - to put it into my own words, all of the relativistic effects are real, but different people in different frames of reference may disagree on that reality. So you're right - reality s typically considered an absolute, but in reality (D'oh) reality is relative.

 

What I find fascinating to try to grok is the fact that there is a speed limit to reality, i.e. if C is an absolute limit to the speed at which information can be transmitted, no matter what, then our experience of the universe is constrained by that speed limit. So if we had a really long ruler and pushed it forwards at nearly C, that ruler would ACTUALLY shrink, because the 'information' (cause and effect of atoms pushing against each other, transmitted forward along the ruler) from the pushing point might have to travel a mile, and by the time it can do that (at C), the pushed end of the ruler is already nearly a mile further forward than when it started.

 

So that universal limit actually limits our experience of reality, and more boggling to me is that "our experience" of reality in this context, IS our reality, because the universe can only have any effect on us, at all, within the constraints of that speed limit.  If a speeding (ALOT ) car shrinks in length because of the universe's inability to transmit information fast enough, such that the car just misses us rather than hitting us, we do live! 

[Hannibal]

 

LifeIsBrief, on 16 Oct 2013 - 07:43 AM, said:

... this part really confuses me.  If you will need twice the calories, and water, to move at twice the speed through time, of someone on the planet earth...  Why won't you age?  How is this not the same as having lived the double time?

 

I think there's some misunderstanding somewhere. Time dilation affects every physical process. It really is time itself that passes at different rates for the accellerating and non-accellerating twin. If the space-twin comes back from the journey after five of his years, and ten years have passed for the earth-twin, then the earth-twin has definitely consumed twice the calories, and aged twice as much, and his clocks have advanced twice as much, and the radioactive carbon-14 atoms in his body have undergone twice as much exponential decay.

 

 

 

(please excuse the weird quote nesting)

 

This - I think LifeISbrief is confusing "travelling to the future" by having one's own time slowed down, relatively speaking, with travelling faster though time (i.e. time flowing faster to get to the future which might sound more intuitive).

I forgot to ask....

 

As someone already mentioned, why does this always come up here? Why don't people just pop over to a physics forum where there are recognised experts who have explained this all a thousand times before, properly with fewer mistakes.

[LifeIsBrief]

This - I think LifeISbrief is confusing "travelling to the future" by having one's own time slowed down, relatively speaking, with travelling faster though time (i.e. time flowing faster to get to the future which might sound more intuitive).

 

I forgot to ask....

 

As someone already mentioned, why does this always come up here? Why don't people just pop over to a physics forum where there are recognised experts who have explained this all a thousand times before, properly with fewer mistakes.

I apologize for not looking through the forums for a similar topic, as I didn't realize that it had already been discussed here.  I thought this was an interesting place to broach the subject, because very few people at FDR believe that perception is reality.  In a typical physics forum, you may get some interesting answers, but you will also find, that most of the people who believe them, don't believe reality exists, which makes it very hard for someone like myself to take them seriously.  Also, when I bring this subject up in a physics forum, I get lots of links to a definition of relativity... If I didn't understand it in Einstein's own words, what are the odds Wikipedia is going to straighten me out?

 

Having someone of a similar mindset to myself re enforce the idea that this is a legitimate scientific theory is helpful.  My experience with universities, is that they tend to encourage belief in all sorts of insane nonsense, and thus I have what could be classified as an unfair bias against their students.  It's lots of "go back to the 18th century", or "if you read the same thing I read, and don't believe it 100%, you think you're smarter than Einstein, so forget you".  The idea that I could be comfortable living in the uncertainty of "Am I on to something, or completely ignorant?", is baffling to most.

 

To be clear, you're saying that as the person on the spacecraft slows through time, the person on earth, has to eat double the calories, not the person on the spaceship?  I still find myself asking "Why?", and "How did we prove that?".  The fact that the largest time dilation experienced by a human, falls into the realm of minutes, makes me think that this is the part which is theory.  Maybe there have been viral, or bacterial studies which prove that growth rates, and calorie consumption are slowed by relativistic movement in time?  I googled that only once without finding anything conclusive, but I'll do so again.  If you happen to be able to link to such a study it would likely put the final nail in the coffin for me.

 

Finally, I do think the idea of matter being a naturally expanding self replicating phenomena, is a bit terrifying for people who believe in god, even though, in my mind, it shouldn't be.  You still have the "gap" of "Why does something exist rather than nothing", and no Lawrence Krauss, has not completely sold me on the idea that the random chance of quantum physics is the answer to that question.  It is an interesting and compelling argument, but I'm not entirely sold.

 

I really appreciate the time you've spent ironing out and refining some of my nonsense, though.

[Hannibal]

 

To be clear, you're saying that as the person on the spacecraft slows through time, the person on earth, has to eat double the calories, not the person on the spaceship?  I still find myself asking "Why?", and "How did we prove that?".  The fact that the largest time dilation experienced by a human, falls into the realm of minutes, makes me think that this is the part which is theory.  Maybe there have been viral, or bacterial studies which prove that growth rates, and calorie consumption are slowed by relativistic movement in time?  I googled that only once without finding anything conclusive, but I'll do so again.  If you happen to be able to link to such a study it would likely put the final nail in the coffin for me.

 

 

 

Ok... lets see if we can sort this out.

So we synchronise 2 atomic clocks and put one on a plane and fly it around the world. When it lands we compare them and the one on the plane is behind the other. To map that to your scenario, the moving clock is the spaceship twin, and that clock/twin has moved through time, relatively to us on the ground with the stationary clock/twin, more slowly.

This test has been done.

 

We synchronise 2 clocks and put 1 on the ground and the other at a high altitude, and wait a while. When we bring them back together the one on the ground is behind the one that was at altitude for the duration. 

This test has been done.

 

The first is due to time dilation because one clock was moving relative to the other.

The second is gravitational time dilation because time passes more slowly in regions closer to the source of gravitational force.

 

So if we've proven that relativistic effects can slow down actions at the atomic level, then why would you suppose that that same physics, at a more course grained level (biology) would be any different? If every atom that made up a man performed all of it's actions at half speed, then why do you suppose that the man, which all of those atoms collectively make up, would find his body chemistry (which is just applied atomic level physics) is not affected in the same way?

[LifeIsBrief]

"So if we've proven that relativistic effects can slow down actions at the atomic level, then why would you suppose that that same physics, at a more course grained level (biology) would be any different? If every atom that made up a man performed all of it's actions at half speed, then why do you suppose that the man, which all of those atoms collectively make up, would find his body chemistry (which is just applied atomic level physics) is not affected in the same way?"

 

First question first... and seriously, I know I might sound a bit obstinate, and I truly appreciate you taking this time to deal with me anyway...  I totally understand that there is a 99% chance I don't get this, but I want to, so... This is what I would say if being totally honest... Any number of unknown variables.

 

The reason I'm willing to pull the Aether out of my bum when talking about the moon getting smaller, is simply that... There may be any number of unknown variables, that humans have yet to come into contact with.  Dark matter, and dark energy, are both purely theoretical, and exist solely to explain why relativity is wrong about entropy... How is that any different from the Aether that the scientist I have a bit of a man crush on (Tesla), proposed?

 

Obviously at the top of a mountain, there is less air pressure, less oxygen, a different consistency to air, temperature... You may say, "Well of course the tests account for that", but http://www.orgonelab.org/miller.htm these are the same criticisms levied against the Miller experiment, and he believed he had accounted for such things.  Miller, in case you don't know, was the person who tried to replicate the Michelson-Morley experiment and failed, over, and over again, instead proving that the Aether existed.  Also, how did they design a clock that accounts for all that?  It seems like people just assume that machines work the same way everywhere.

 

Why does movement effect clocks?... I agree that light speed is a constant, so if all of our modern clocks involve the movement of light in relation to specific atoms, or the movement of light generally... of course they will prove that time is light based. Even if the atomic clocks have nothing to do with light, once you accept the idea that relativity might not be correct you almost have to assume there is an alternate variable effecting the results (the most popular of which, in scientific circles, has been the ether/Aether).  It almost seems as though relativity uses Occam's Razor, as a proof, rather than an argument.  If the Aether exists, then there are alternate amounts of energy passing through each clock depending on the consistency of the space earth is moving through at any given time.

 

I realize that this is conspiratorial in nature.  It sounds like I'm saying that everyone is intentionally using variables that they understand to prove something they know to be wrong... but, I promise, I'm just suggesting that we don't know everything about physics.  The Aether could be a real thing, or there could be a new force, completely undiscovered, which interacts with motion in a way we do not understand.

 

Finally, that is the more crazy answer... In my mind, the slightly more sane answer, and I do mean slightly, because I still believe that I am likely wrong... The Heisenberg Uncertainty Principle.  We're just measuring wrong.  You will continue to see changes, but they won't really exist, because it's impossible to know the speed and direction of anything, at any time.  I'm actually not entirely sure I believe in this principle either... but it entirely explains why light might be giving us objectively incorrect results to our experiments.  Maybe... just maybe, the neurons in your brain fire slower, but the atoms in your brain experience time objectively.

 

I know I've said this numerous times, but I really do realize I'm armchair quarterbacking the infinite nature of reality, without the proper physics degree.  This is probably dime store literature more than it's physics, but the fact that my favorite scientist died believing it, gives me that tiny 1% hope...  Also, I'm not sure if you realize this, but, if relativity is correct, we can never leave the solar system.  Earth is it for humanity... I find that very sad, and I don't want to believe it, which again, probably creates my confirmation bias, but if you're willing to try to explain it, thank you so much for your time. I hope, more than think you're wrong...

[RestoringGuy]

So that universal limit actually limits our experience of reality, and more boggling to me is that "our experience" of reality in this context, IS our reality, because the universe can only have any effect on us, at all, within the constraints of that speed limit.  If a speeding (ALOT ) car shrinks in length because of the universe's inability to transmit information fast enough, such that the car just misses us rather than hitting us, we do live! 

Good points.  I agree there is a sense a moving ruler has "actually shrunk", there is also a sense a stationary ruler has shrunk because it could be witnessed from the moving frame.  Like the spaceship time dilation scenario, neither ruler has really officially shrunk (in standard sense of making "a < b" comparison) until we decide which frame is "the one" in which the shrinkage comparison ought to take place.Yes, the speed limit thing has baffled me at times, and I have pointed a laser pointer on a distant wall and thought man if I swing the pointer really fast, that dot ought to move faster than c.  Anyway, without quantum mechanics, yes it might seem everything in our information cone (our timelike event horizon, or whatever) constitutes all of our reality.  On the other hand, with quantum entanglement we are almost forced to deal with information flowing at faster than c.  But it's information between remote objects we must inspect after the fact.  That is, as I understand QM, the superluminal information cannot be environmentally exposed or utilized except by its wavefunction carriers, and those wavefunctions we are forbidden to inspect in way that gives transmittable data at a rate faster than c.The entangled particles themselves seem to have no trouble breaking this limit, as if their indeterminacy and uncertain momentum grants small particles a different frame.  Perhaps its a little bit like why light "slows down" through water and glass.  It doesn't slow in a technical sense, but we observe that light slows because the light can not travel in a microscopically straight line (it is scattered and re-emitted off all the transparent matter, giving us an illusion of slower than c).  My theory is it's possible the reverse is true, that light travels much faster than c, but empty space (without any entanglement at work) acts as an obstacle, taking light on a journey that is not perfectly straight.  Entanglement is a shortcut, but it is a fragile shortcut that can't be leveraged by heavy matter or near a strong gravitational field.

[LifeIsBrief]

Oh, I forgot the most important part of my answer...  Organic matter vs. inorganic matter.  Why would something work for one, but not the other?  Organic matter requires the consumption of energy to move through time.  Inorganic matter does not.  For a particle to move through time at double speed, it would require no extra food and water, or energy.  So, in my mind, we still have to prove that organic matter would react the same way.  I would actually suggest that time does not exist for light, or particles, time is a construction of organic matter.

 

I also said that I believed your neurons would fire more slowly, that was phrased poorly.  I think it's possible that your neurons fire exactly as often, but the photons move slowly.  I still don't quite understand how we could prove that inorganic matter didn't age, or experience time.

[Hannibal]

Oh, I forgot the most important part of my answer...  Organic matter vs. inorganic matter.  Why would something work for one, but not the other?  Organic matter requires the consumption of energy to move through time.  Inorganic matter does not.  For a particle to move through time at double speed, it would require no extra food and water, or energy.  So, in my mind, we still have to prove that organic matter would react the same way.  I would actually suggest that time does not exist for light, or particles, time is a construction of organic matter.

 

I also said that I believed your neurons would fire more slowly, that was phrased poorly.  I think it's possible that your neurons fire exactly as often, but the photons move slowly.  I still don't quite understand how we could prove that inorganic matter didn't age, or experience time.

 

Ok, this is going to sound rude, but I REALLY don't intend it that way.

 

You don't even understand basic A-Level (I don't know what they might be called where you are from) physics, let alone theories of relativity. How can you expect anyone to take you at all seriously when you clam to doubt a theory which you have no understanding of?    

 

I can't use my own judgement to say whether it's true or not, because I am not a physicist and only know a very little popular science out of random curiosity. It's rational for me to believe the scientific community because I accept the scientific method as valid, so I trust those that practise it to convey the best theory they have at the time.

 

The trouble is that I cannot engage in a useful discussion of relativity with you (to the limits that my very casual acquaintance of it allows me) because you don't even understand elementary physics. There's nothing wrong with that, but to then disbelieve the consensus of the scientific community based on your own ignorance of the subject is.... I can't find words for it. Arrogant? Ignorant? Irrational? 

 

"Organic matter" is just a name given to a collection of inorganic matter, which is arranged in a particular way. It's the same stuff.

Good points.  I agree there is a sense a moving ruler has "actually shrunk", there is also a sense a stationary ruler has shrunk because it could be witnessed from the moving frame.  Like the spaceship time dilation scenario, neither ruler has really officially shrunk (in standard sense of making "a < b" comparison) until we decide which frame is "the one" in which the shrinkage comparison ought to take place.Yes, the speed limit thing has baffled me at times, and I have pointed a laser pointer on a distant wall and thought man if I swing the pointer really fast, that dot ought to move faster than c.  Anyway, without quantum mechanics, yes it might seem everything in our information cone (our timelike event horizon, or whatever) constitutes all of our reality.  On the other hand, with quantum entanglement we are almost forced to deal with information flowing at faster than c.  But it's information between remote objects we must inspect after the fact.  That is, as I understand QM, the superluminal information cannot be environmentally exposed or utilized except by its wavefunction carriers, and those wavefunctions we are forbidden to inspect in way that gives transmittable data at a rate faster than c.The entangled particles themselves seem to have no trouble breaking this limit, as if their indeterminacy and uncertain momentum grants small particles a different frame.  Perhaps its a little bit like why light "slows down" through water and glass.  It doesn't slow in a technical sense, but we observe that light slows because the light can not travel in a microscopically straight line (it is scattered and re-emitted off all the transparent matter, giving us an illusion of slower than c).  My theory is it's possible the reverse is true, that light travels much faster than c, but empty space (without any entanglement at work) acts as an obstacle, taking light on a journey that is not perfectly straight.  Entanglement is a shortcut, but it is a fragile shortcut that can't be leveraged by heavy matter or near a strong gravitational field.

 

I should mention that those were just me rambling about the boggles boggling around in my mind - I can't properly understand it, so my examples probably might never occur due to some other factor o.O For example i'm assuming some method to stop the ruler breaking.

 

The laser pen at a distant wall - lets say the moon - still nothing is moving faster than C. A light might shine on point X1 at time t1, and then be shining on point X2 at time t2 such that distance x2-x1 divided by time t2 - t1 is greater than C, BUT no actual thing will have moved faster than C, and there is no way that any information could be transmitted faster than C because a receiver at X2 when the light hits it could not have been aware already that it had previously hit X1. I know you probably already realise this - just saying. 

[LifeIsBrief]

That's a shame.  What's most confusing to me, is that I actually did very well in college physics... I'm good at regurgitating things I'm told.  I just then have a tendency to question why I was told them, and look at alternative views, creating my own makeshift theories.  I could probably pass a test on relativity right now, I just wouldn't agree with some of the answers I would have to write in to be "correct".  Maybe it's just been too many years of mixing, matching, and not functionally using physics, that makes my communication difficult to understand.

 

Living organisms, absorb, and functionally use energy to maintain their structure over time.  Atoms don't, from my understanding.  Maybe I'm unaware of atoms needing to absorb radiation to maintain their structure, in which case they would operate in a similar way to organic material...  If so, I'd have some reading to do.

 

I don't think it's arrogant, to ask questions...  The point would be to overcome ignorance. Irrational would be to suggest that relativity is definitely wrong, but I wouldn't go that far.  I could be kind of stupid, or I might simply be emotionally refusing to believe that it would take infinite energy for us to move to the nearest goldilocks planet in less than a lifetime.  Meh... What you gonna do?  Life is brief.

 

Thanks for trying anyway.

 

Edit: I just want to add, that I asked "Is he just confusing time with light?" and "Isn't a precision clock a light clock?" to which someone responded "No, and no", with no explanation... They happen to be completely wrong in that regard, unless they were arguing over the semantics of microwaves not being the same as light, because it's not visible.  Every "precision clock" we use, including all the ones in space, simply use the constant frequency of light to keep time... So, of course, when you move them, and light has a constant speed, they slow down...  http://en.wikipedia.org/wiki/Atomic_clock

 

"In 1967, the 13th General Conference on Weights and Measures first defined the International System (SI) unit of time, the second, in terms of atomic time rather than the motion of the Earth. Specifically, a second was defined as the duration of 9,192,631,770 cycles of microwave light absorbed or emitted by the hyperfine transition of cesium-133 atoms in their ground state undisturbed by external fields."

 

In fact, once you accept that the speed of light, is what defines time... Haven't you made relativity unfalsifiable?

[ribuck]

I don't think it's arrogant, to ask questions... 

 

It's discourteous to keep throwing out a stream of objections and expecting others to jump through hoops to write explanations.

 

If you want to debunk something, you either need to fully understand what you are debunking (so that you can expose an error), or you need to post an alternative theory that better-matches the experimental evidence.

[RestoringGuy]

Living organisms, absorb, and functionally use energy to maintain their structure over time.  Atoms don't, from my understanding.  Maybe I'm unaware of atoms needing to absorb radiation to maintain their structure, in which case they would operate in a similar way to organic material...  If so, I'd have some reading to do.

Many bad assumptions.  It happens all the time. Atoms absorb energy to move their electrons to different orbitals, or atoms move relative to one another, taking in kinetic energy from the surroundings.  That subsequently makes some reactions more likely than others.  It makes many inorganic compounds possible, like water for example.   "Living organisms" just do this in a way you are more likely to recognize and label "functional".  Atoms do not care if they constitute living matter and suddenly realize it and change how energy flows around them.  It is not true there is living "structure maintained" in a techical sense, because our cells are replaced routinely, and we just call them the same. It is much as rainfall may replenish a puddle and you can call it the "same" puddle if you wish.   It is a linguistic convention and that is all.

[LifeIsBrief]

I would suggest, "some poor linguistic choices", over "many bad assumptions"... because you don't even seem to be challenging my premise.  If radiation makes a an electron move to a different orbital, it doesn't necessarily give us a functioning picture of time.  A living organism, on the other hand, is required to do time sensitive tasks in order to survive, so how they move through time, may, or may not effect that, but we would have to prove it.  I assume I've worn out my welcome on this subject however, so I'll just relax and go back to agreeing with you all that anarcho capitalism is awesome, because... It is.  We agree on lots of things, I don't need you all to take my theories on Einstein seriously. 

 

I imagine that there are a couple people who read this and think it's interesting.  More who read it, and think I'm an idiot... I can live with that.  I'm pretty sure the last sentence of my previous response is the most damning, though I should have changed a word or two. "Once you accept that the speed of light, is what defines time... Haven't you made parts of relativity unfalsifiable?"  I could really just be kind of stupid though... That's life, it's short... Peace and love.

[Hannibal]

I would suggest, "some poor linguistic choices", over "many bad assumptions"... because you don't even seem to be challenging my premise.  If radiation makes a an electron move to a different orbital, it doesn't necessarily give us a functioning picture of time.  A living organism, on the other hand, is required to do time sensitive tasks in order to survive, so how they move through time, may, or may not effect that, but we would have to prove it.  I assume I've worn out my welcome on this subject however, so I'll just relax and go back to agreeing with you all that anarcho capitalism is awesome, because... It is.  We agree on lots of things, I don't need you all to take my theories on Einstein seriously. 

 

I imagine that there are a couple people who read this and think it's interesting.  More who read it, and think I'm an idiot... I can live with that.  I'm pretty sure the last sentence of my previous response is the most damning, though I should have changed a word or two. "Once you accept that the speed of light, is what defines time... Haven't you made parts of relativity unfalsifiable?"  I could really just be kind of stupid though... That's life, it's short... Peace and love.

 

I suspect that this would be easier to communicate over a pint in the pub, which is why I said i really didn't want to sound rude - talking one at a time via text is not the easiest way to clear things up, so I'd suggest not taking our objections personally.

 

 

 

Once you accept that the speed of light, is what defines time...

 

This is a significant problem for me. I don't now where you get that idea from. It's more like light is massless, so therefore it moves as fast as is possible, and that just happens to be C.

 

I imagine it like this -

 

reduce 4d spacetime to 3d so that you can visualise it. x & y is 2 directions in space, and z is time. If you take a 30cm ruler and suppose that that represents the speed at which stuff moves through space-time (a fixed constant) then:

 

*standing it upright means that you aren't moving at all through space, but the full ruler length through time (z). 

 

* now tilt it a little on the x axis and you can see that you are now moving in x direction through space a little, but you've had to sacrifice some movement through time (z axis).

 

* now tilt it the same, but including some y axis. Now you'll see that you're moving through both x and y space, but you've had to sacrifice even more y axis (time).

 

So it's a bit like there is a constant speed which everything moves through space-time, and if you don't move in space at all then you move at maximum speed through time. Or if you move through space as fast as possible then you don't get to move through time at all (like a photon).

 

 

 

But really... a physics forum will be full of people that can explain it really well, and so when you put forward your objections they will be able to point out exactly where you've miscalculated.

 

 

Note: obviously talking about 'moving' through space independently of time is somewhat contradictory as movement by definition implies a before & after. This is just a limitation of the english language.

[FriendlyHacker]

You need to read a tiny bit more about Physics before saying that you know more about it than the likes of Einstein, Bohr, Heisenberg and Hawking.But hey, maybe you're a Genius, so if you are a Genius show me your mathematical proof that relativity is wrong, and collect your Nobel prize.

 

 

1 - Show mathematical proof

2 - ????

3 - Profit

[Pepin]

A great lecture series I'd recommend on the topic is here. The math may more sense of the theory than a description of it. Then I'd recommend watching this, which is less complex, but really gratifying if you understand the first series.

[anarcho-science-dude]

Didn't read all the comments though those videos Pepin posted might be good (haven't seen them yet). One problem I saw in the comments is that you're thinking in 3 dimensions. The theory of relativity is a 4 dimensional theory and that doesn't mean an object moving through the 4th dimension. All 4 dimensions are linked to each other and to energy and mass.

[SoberEnough]

Seeing this is my first legitimate post on FDR and I actually come from this field maybe I can try to take some time to explain what "relativity" in the sense of Einstein is. I'll try to be succinct and avoid a tl;dr situation.

 

Back in the days, there was Newtonian mechanics. Newton told us how to get the position of a particle given the nature of the forces imparted on it and a mathematical method called calculus. "Mechanics" in this context meant that the path of a particle was completely determined from initial conditions as time was viewed as an almost unique "parameterization" of the states of a system. The notion of determinism is still true in relativistic dynamics, this is how we differentiate classical from quantum mechanics.

 

The only qualms that exist between the relativistic (in the sense of Einstein) and traditional dynamics is the statement that "time is viewed as an almost unique paramaterization" of the state of a system. 

 

The "principle of relativity" predates Newton, in fact, Newton makes considerations of it in his mechanics. Galileo is credited with first realizing that the laws of physics are invariant in frames where we consider relative distances. If you have two observers observing a rock fall, the one which is 3 meters away from the original uses the same laws to predict dynamics. The results of either experimenter are equivalent by the addition of some number.

 

Einstein's notion of relativity was not that of what is actually moving but whether or not the laws of physics are invariant in certain conditions. Historically speaking, Michelson and Morley produced an experiment at the turn of the century that implied (although the implication wasn't clear to scientists at that time) that the speed of light was invariant with respect to your choice of inertial frame.

 

An inertial frame is any choice of origin for an experimenter moving with constant velocity (when bodies experiment we need to generalize these notions, but I digress). Non-relativistically (in the sense of Galileo) speaking, if you are moving at 5 miles per hour and you throw a baseball at 1 mile per hour (you got a weak arm) relative to yourself, to an observer stationary with respect to the 5 mph frame the ball travels at 6 mph. This is a one-dimensional case, but it is easy to imagine. This is just a property of vectors. The 'stationary' ball in the 5 mph frame is in fact already moving at 5 mph relative to your static position, to impart additional velocity makes it travel faster.

 

What Einstein wanted to know is if light behaved in this same way, as the propagation of waves in this time period were impinged on the existence of media that were subject to (Galilean) relativistic properties. Einstein made the very correct assumption that light could propagate through vacuum and that the speed of light must therefore (in vacuum) be invariant in all inertial frames on the basis of the Michelson-Morley experiment.

 

If you work with this assumption, validated by experiment, the effects of time dilation are trivial to demonstrate. The attached picture illustrates the following situation:

 

 

In FRAME 1, you are moving at speed v with a 'light clock' of height h which flashes a particle of light at t₁=0 where it hits a mirror and is reflected back into a detector which produces an audible beep. You measure the time difference to be as illustrated.

 

In FRAME 2 you are stationary with respect to FRAME 1, the time difference has to be determined by using Pythagorean theorem. Notice that the hypotenuse of the triangle MUST be (ct₂ )/2 as this is the actual magnitude of distance sweeped by the photon. 

 

With some minor algebra you get that t₂ and t₁ in fact not equal, but different by a scaling factor (called the Lorentz factor). The question of where relativity is important is in fact determined by the Lorentz factor and if people want I can go into the details of that, and some other superfluous detail I didn't regard here (things that motivate the adoption of Minkowski space for dynamics).

 

The point is this: you don't have to cry about the philosophical notions of relativity. If it is indeed true that the speed of light is invariant in all inertial frames we measure (we have countless experiments to corroborate this fact), then time-dilation occurs. What's more, electromagnetism implies special relativity through its inherent Lorentz invariance. You can sit around pontificating about your own greatness (not that I am saying that is what OP is doing, peopledo this) but the predictions made by SR are being constantly verified. We have computers in space right now that are demonstrating it within fractions of seconds as we speak.

I'm trying not to introduce too much jargon, but someone mentioned a hypothetical "4th dimension." It is important to note that the only people I know of that take that shit seriously are string theorists and they are far from the realm of falsifiability at the present time.

 

Strictly speaking, physicists and mathematicians know the divide between the addition of a dimension to complete Minkowski space as a model for special relativity and physical reality. One adopts Minkowski space to avoid arguing about this crap.

[Bulbasaur]

Very nice summary.