It's about time.

[Age]

Sure, the speed of light is the speed of light ... the speed of sound is the speed of sound... etc... "regardless of the distance it travels"...

The thing with the speed of light being this magical constant c is that it's only constant in a vacuum, and as Paradigmer is alluding to, there is no such thing as an absolute vacuum.

Here is ANOTHER clarifying question:
If the speed of light is ONLY constant in a vacuum, and there is NO such thing as a vacuum, then HOW does any one KNOW that the speed of light is a constant?

The speed of sound is dependent on the medium and the density of the medium. For example in air the speed of sound at sea level is about 750mph, depending on the temperature and air pressure. In water, it's over 3000mph. If the air (or water) is moving, that changes the speed relative to the listener. If the wind is blowing in the direction of the source of sound, then speed of sound you will measure is 750mph minus however fast the wind is blowing. Conversely, if the wind is blowing from the sound source, then what you measure is 750mph plus windspeed. And then if you or the source is moving, that too has its effect. Most of that is true of light, with one crucial difference - no matter what the relative speeds are, you will always measure the speed of light as the speed appropriate to the medium and conditions it is passing through. That's down to the observed length contraction - the faster you are going, the more distance is contracted, so although the relative speed is more than c in some meaningless 'absolute' sense, the distance the oncoming photon appears to travel is much less - cancelling out the superluminal speed form your perspective. Conversely, a photon that is catching you up from the rear has a relative speed which is much less than c, but because space appears stretched out, it appears to travel much further so the miles per hour are measured as the same.

...but, as I see it, the distance of travel is the same, no matter if an external observer might see something else...

Well, if it works for you, and it's consistent with the evidence, don't mess with it. Just be willing to change your mind in the light of new evidence. That's pretty much the situation most of us find ourselves in.

Great advice.

[Age]

If any one is Truly interested in learning and understanding this further, then all of this can be explained.

Age, if you are Truly interested in explaining it to anyone who cares to listen, could you do so in your own thread please?

But I am NOT interested in those who 'care to listen'. I did NOT even write nor say this, but you twisted around and distorted what I ACTUALLY wrote and said. Those who Truly listen to NOT see NOR hear things, which I did NOT say NOR write.

I am INTERESTED in those who are 'interested in learning and understanding more and anew', as I wrote AND EXPLAINED. Those ones WILL show and REVEAL themselves, to me. And when they do, then I am Truly interested in sharing, explaining, and understanding WITH them.

Even you wrote; " explaining 'it' ". Now, what do you think or believe the 'it' IS, exactly?

If someone was Truly listening to what I was saying, then they could and would explain what the 'it' IS, exactly. And, then I would have more evidence of those who are Truly listening and Truly are curious and interested in learning and understanding more and anew.

[AlexW]

That's down to the observed length contraction - the faster you are going, the more distance is contracted, so although the relative speed is more than c in some meaningless 'absolute' sense, the distance the oncoming photon appears to travel is much less - cancelling out the superluminal speed form your perspective

Well, yes, thats what I was saying: the object itself doesn't as such travel faster (light would still travel at the speed of light) but it actually contracted the distance it travelled ... and: it is only "alive and measuring time" when actually in existence on the screen
The speed is still the speed of light, but due to the contracted distance less time (which is nothing but counted „bits“ of movement) has ticked past.

[uwot]

...the object itself doesn't as such travel faster (light would still travel at the speed of light) but it actually contracted the distance it travelled ...

Do you really mean this? Suppose someone took a journey from the Earth to the Sun; would someone at a suitable vantage point see the Earth and Sun get closer together?

[seeds]

... as far as I can tell, this is not a proof (or proper explanation) for the clock actually ticking less often when travelling at higher speeds... but maybe I am missing something?

Yeah, I see where you're coming from and in the case of the stone you are right. At normal speeds we simply add the horizontal speed to the vertical speed, so we would judge that the stone on the train is going faster overall, because it has travelled further in the same time. But the speed of light is the speed of light regardless of the distance it travels; hence the further it travels, the longer it takes.
(Note for pedants: Yup, relativity works even at low speeds, but if you can perceive the difference of a gazillionth of a second between the stones landing, you're a better man than I. Or woman.)

The following is just my own speculative blatherings, but I suggest that the thought experiment of the person on the moving train dropping a stone (or a ball, or whatever), vs the stationary person doing the same thing, was simply meant to help visualize what the word “relativity” means with respect to different observers in different frames of reference.

Whereas, on the other hand, to visualize the relativity of time, one needs to use other types of thought experiments involving varying gravitational fields, or increases in mass.

For example, if we take two identical clocks and keep one here on earth and place the other one on a planet whose gravitational field is, say, a thousand times stronger than that of the earth’s gravitational field,...

...then we can imagine the cogs and gears of the clock on the other planet (right down to the infinitesimal cogs and gears of its quantum constituents) as being constrained or inhibited (literally slowed down) by reason of being subjected to the stronger gravitational field of the other planet.

And if after 10 years we were to bring the two clocks back together in a neutral area in the vacuum of space, we would discover that the less constrained earth-clock would have ticked-off far more seconds than the other clock.

Now, theoretically, the same thing would occur with the cogs and gears of the quantum constituents that comprise the bodies of humans who are placed in a similar situation of stronger and weaker gravitational fields.

And that brings us to the “twin paradox” and how if one twin stayed on earth while the other twin traveled in a frame of reference (a space ship) that is moving close to the speed of light...

(a situation that allegedly increases the mass [gravity] of the ship [and the twin] in a way that is comparable to being subjected to the greater mass and gravity that was experienced by the twin clock in the other example)

...then a similar outcome is incurred, wherein the “clockwork” of the quantum fabric of the spaceship and the spaceship twin would have moved slower than that of the earth-bound twin, thus slowing down the aging process.



In other words, the way in which we experience the movement or passing of what we call “time,” seems to be inextricably dependent upon the strength or weakness of the gravitational field of the particular frame of reference we are held within, and how that gravitational field affects the speed of not only the movement of light,...

...but also, and again, the speed of the movements of the quantum constituents that comprise our bodies and brains and the overall frame of reference itself.
_______

[uwot]

The following is just my own speculative blatherings, but I suggest that the thought experiment of the person on the moving train dropping a stone (or a ball, or whatever), vs the stationary person doing the same thing, was simply meant to help visualize what the word “relativity” means with respect to different observers in different frames of reference.

Well, it's meant to help visualise the time dilation due to motion, which is described in Special Relativity.

Whereas, on the other hand, to visualize the relativity of time, one needs to use other types of thought experiments involving varying gravitational fields, or increases in mass.

That's gravitational time dilation, as described in General Relativity.

For example, if we take two identical clocks and keep one here on earth and place the other one on a planet whose gravitational field is, say, a thousand times stronger than that of the earth’s gravitational field, then we can imagine the cogs and gears of the clock on the other planet (right down to the infinitesimal cogs and gears of its quantum constituents) as being constrained or inhibited (literally slowed down) by reason of being subjected to the stronger magnetic field of the other planet.

Well seeds, there are two things that demonstrably affect how fast clocks tick, motion and gravity. There is no evidence that non-ferrous clocks are affected by magnetic fields as far as I know.

And if after 10 years we were to bring the two clocks back together in a neutral area in the vacuum of space, we would discover that the less constrained earth-clock would have ticked-off far more seconds than the other clock.

Seeds me old china, the experiments have been done. Atomic clocks are so fantastically accurate that they can register a difference in Earth's gravitational field at about a foot's elevation. That's General Relativity. Nor do you have to move a clock very far, at the same elevation, for the effects described in Special Relativity to register.

Now, theoretically, the same thing would occur with the cogs and gears of the quantum constituents that comprise the bodies of humans who are placed in a similar situation of stronger and weaker gravitational fields.

Not theoretically, demonstrably.

And that brings us to the “twin paradox” and how if one twin stayed on earth while the other twin traveled in a frame of reference (a space ship) that is moving close to the speed of light...

We're a way off doing that with human beings, but, again, it's been done with clocks.

(a situation that allegedly increases the mass [gravity] of the ship [and the twin] in a way that is comparable to being subjected to the greater mass and gravity that was experienced by the twin clock in the other example)

Not really. One way to measure mass is by how much you have to push it to push it to move it, which because everything is moving really means to make it move faster. Consider the Bugatti Veyron, a pointlessly fast car that people with silly money will buy simply because it is the world's fastest production car. Someone, I forget who, comes along and pips it by an mph or two. Bugatti then have to beef up their motor by 150bhp, about the same bhp as a Mini Cooper, which does 150mph. At the silly speeds the Bugatti does, about 250mph, that extra 150bhp only gets another 5mph. At that speed, the air is so compressed, it's like driving through cake. At close to the speed of light, even in the apparent emptiness of space, it's like driving through granite, and the bhp you need in your Bugatti is waaaaay off the scale. As the speed of light is as fast as anything can be moved out of the way, if you could travel at the speed of light, you would effectively be moving through a solid block, which you can't, hence nothing with (rest) mass can travel at the speed of light.

...then a similar outcome is incurred, wherein the “clockwork” of the quantum fabric of the spaceship and the spaceship twin would have moved slower than that of the earth-bound twin, thus slowing down the aging process.

Did you read the OP? Granted it's a bit wordy for a forum, but I do try to explain why 'time slows down' (as in clocks tick less) the faster one is moving.

In other words, the way in which we experience the movement or passing of what we call “time,” seems to be inextricably dependent upon the strength or weakness of the gravitational field of the particular frame of reference we are held within...

Well, the whole point of relativity is that nothing affects how we experience time. It doesn't matter what inertial frame or gravitational well you are in, time is always counted at the same rate. Our subjective experience of time just depends on what we happen to be doing, which Einstein put like this: "When you sit with a nice girl for two hours you think it's only a minute. But when you sit on a hot stove for a minute you think it's two hours. That's relativity."

...and how that gravitational field affects the speed of not only the movement of light, but also, and again, the speed of the movements of the quantum constituents that comprise our bodies and brains and the overall frame of reference itself.

Now seeds, be honest, did you actually read the OP?

[AlexW]

Suppose someone took a journey from the Earth to the Sun; would someone at a suitable vantage point see the Earth and Sun get closer together?

No, they wouldn't - its not as if space would actually contract and then things suddenly appear to be closer together.

Its not that space contracts at all, its rather that the fast traveling object "skips" parts of the distance that a slow moving object travels through.
I attempted to explain this using the screen analogy - very fast moving objects (faster than the refresh-rate of the screen) simply skip parts of the pixels in their trajectory.

The maximum speed, when measured from the perspective of an external observer who measures the time it takes the object to move from A to B, is faster than the speed of light, while the maximum speed of the object itself is still c.
At least thats the case for the parts of the journey it travels in relativistic space/time - while its speed increased to infinity "within" the sections it skips (which is actually no speed at all - its absolute presence, or rather absence, in/from the relativistic plane) - just like an object vanishes from a screen and pops up some place else - it didn't accelerate to infinite speed, it simply vanishes at location A and materialises at B.

I propose that this vanishing and reappearing happens many times a second - light having a frequency of somewhere between 430–750 terahertz this popping out and back into relativistic spacetime would happen VERY often every second.

[seeds]

For example, if we take two identical clocks and keep one here on earth and place the other one on a planet whose gravitational field is, say, a thousand times stronger than that of the earth’s gravitational field, then we can imagine the cogs and gears of the clock on the other planet (right down to the infinitesimal cogs and gears of its quantum constituents) as being constrained or inhibited (literally slowed down) by reason of being subjected to the stronger magnetic field of the other planet.

Well seeds, there are two things that demonstrably affect how fast clocks tick, motion and gravity. There is no evidence that non-ferrous clocks are affected by magnetic fields as far as I know.

Yeah, you’re right, uwot.

I carelessly conflated magnetism with gravity. I should have worded that using “stronger gravitational field” (of which I have now corrected in the original post).

And if after 10 years we were to bring the two clocks back together in a neutral area in the vacuum of space, we would discover that the less constrained earth-clock would have ticked-off far more seconds than the other clock.

Seeds me old china, the experiments have been done. Atomic clocks are so fantastically accurate that they can register a difference in Earth's gravitational field at about a foot's elevation. That's General Relativity. Nor do you have to move a clock very far, at the same elevation, for the effects described in Special Relativity to register.

uwot, me old bean, I wasn’t trying to detract from the beautiful models you supply. No, I was simply trying to provide a more dramatic way (make that more simplistic way) of visualizing the situation, as in something a little more pedestrian than atomic clocks. (I did say that these were merely my “speculative” blatherings.)

Now, theoretically, the same thing would occur with the cogs and gears of the quantum constituents that comprise the bodies of humans who are placed in a similar situation of stronger and weaker gravitational fields.

Not theoretically, demonstrably.

Either way, I’m assuming that you tacitly agree with what I wrote, yes? no?

And that brings us to the “twin paradox” and how if one twin stayed on earth while the other twin traveled in a frame of reference (a space ship) that is moving close to the speed of light...

We're a way off doing that with human beings, but, again, it's been done with clocks.

Well, if it has been done with clocks, then “theoretically” (am I allowed to use that word in this instance?), it should also apply to humans, no? - (seeing how they are made of the same fundamental “stuff” as clocks).

(a situation that allegedly increases the mass [gravity] of the ship [and the twin] in a way that is comparable to being subjected to the greater mass and gravity that was experienced by the twin clock in the other example)

Not really. One way to measure mass is by how much you have to push it to push it to move it,...

Yes, and all of my (perhaps erroneous) assumptions about that particular issue which, admittedly, were established many years ago via my earlier readings that always seemed to suggest that all of the extra amount of energy one must use to push an object to velocities approaching the speed of light, gets transformed into the object’s mass (relativistic mass). And that, to me (rightly or wrongly), seemed to imply an increase in the object’s gravitational strength (hence my loosely comparing it to the higher gravity of a more massive planet).

I mean, even today, if you type into Google the following...

“At velocities approaching the speed of light does an object acquire greater mass?”

...one of the first things to pop-up is this:

A particle moving at one-fifth the speed of light (60,000 km/sec or 37,000 mi/sec) has a mass only 2% greater than its rest mass. When a particle's speed approaches the speed of light, however, the mass increase (called the relativistic mass increase) is significant.

I now realize that there are disputes regarding the nature of “relativistic mass” and whether it is real or not. However, whatever is taking place at extreme velocities, it still apparently produces the effect of slowing down time in a way that seems similar to how strong fields of planetary gravity slow down time. Right?

Now seeds, be honest, did you actually read the OP?

Admittedly, not all of it. But from what I did cover, it has the makings of becoming another one of your splendid and skillfully written articles for the magazine...(to which I confess being jealous of your inroads to the PN editors. I can’t even get them to respond to a simple little cartoon I emailed them. Got any tips?)
_______

[Paradigmer]

Its not that space contracts at all, its rather that the fast traveling object "skips" parts of the distance that a slow moving object travels through.
I attempted to explain this using the screen analogy - very fast moving objects (faster than the refresh-rate of the screen) simply skip parts of the pixels in their trajectory.

The maximum speed, when measured from the perspective of an external observer who measures the time it takes the object to move from A to B, is faster than the speed of light, while the maximum speed of the object itself is still c.
At least thats the case for the parts of the journey it travels in relativistic space/time - while its speed increased to infinity "within" the sections it skips (which is actually no speed at all - its absolute presence, or rather absence, in/from the relativistic plane) - just like an object vanishes from a screen and pops up some place else - it didn't accelerate to infinite speed, it simply vanishes at location A and materialises at B.

I propose that this vanishing and reappearing happens many times a second - light having a frequency of somewhere between 430–750 terahertz this popping out and back into relativistic spacetime would happen VERY often every second.

Oh man this forward time travel explanation is sensational!

However, it is merely a situation that could only happen in the virtual reality that does not refer to the objective reality.

This relativistic concept despite also could not be validated in the subjective reality of the contemporary Einsteinian relativism, its idea could still be pragmatic.

This concept nevermind the reality could be pragmatic for the box office hits by the team Holywood if materialized in their blockbuster movies; the film industry needs people with such ideologies.

[surreptitious57]

If someone was Truly listening to what I was saying then they could and would explain what the it IS exactly

The it is obviously [ very obviously ] the knowledge and understanding that exists within your brain
And less you reveal that knowledge and understanding no one can know or understand what you do

[uwot]

Now, theoretically, the same thing would occur with the cogs and gears of the quantum constituents that comprise the bodies of humans who are placed in a similar situation of stronger and weaker gravitational fields.

Not theoretically, demonstrably.

Either way, I’m assuming that you tacitly agree with what I wrote, yes? no?

I do. Here's the bit in the OP where I say so:

So why wouldn't you notice? How is Galileo’s Principle of Relativity preserved? Well, the speed of light is as fast as anything can go. And just as the light in the light clock is going as fast as it can in the same direction as the spaceship, every atom in your body is doing the same, so there’s no interaction between the atoms and molecules in your body - no biological processes, no mental processes - your body doesn’t age and your brain doesn’t think. There’s no image of you in the mirror, and you don’t even know it. For you time stops.

Now seeds, be honest, did you actually read the OP?

Admittedly, not all of it. But from what I did cover, it has the makings of becoming another one of your splendid and skillfully written articles for the magazine...(to which I confess being jealous of your inroads to the PN editors. I can’t even get them to respond to a simple little cartoon I emailed them. Got any tips?)

Very kind of you to say so. As for tips, I cannot recommend thorough research highly enough.

[surreptitious57]

If the speed of light is ONLY constant in a vacuum and there is NO such thing as
a vacuum then HOW does any one KNOW that the speed of light is a constant ?

Light would be a constant in an absolute vacuum because there would be nothing else to slow it down such as gravity or mass
But absolute vacuums do not exist in Nature because if they did they would have dimension to them so would not be absolute

[surreptitious57]

A photon will only stop travelling at light speed when it is slowed down by either an object or force
Until then it will carry on travelling at c in empty space even though that is not an absolute vacuum

[surreptitious57]

Anything that is massless such as a photon can only travel at c in empty space
So were the Universe entirely empty a photon would travel in it for all of time

[uwot]

I propose that this vanishing and reappearing happens many times a second - light having a frequency of somewhere between 430–750 terahertz this popping out and back into relativistic spacetime would happen VERY often every second.

As far as I can tell, those bits of space that the fast moving objects in your model flit between are the same bits of space that the light in Einstein's light clock actually travel through. It just seems simpler to stick with a fairly mundane explanation, but again, if your model makes more sense to you, as the saying goes; if it ain't broke, don't fix it.