Relation of time and speed of light

[disarray]

With regards to the question as to why nothing can go faster than light, or, to be more precise, why is the speed of light 299,792,458 metres per second and not, for example, 4529553 m/s.

 

I think that it is expecting too much to ask why it is at that particular speed, instead of, say a 100,000 metres faster of slower or whatever. Rather, I think a more fruitful question to ask

is why is their a limit to the speed at all.

 

I imagine that the answer has something to do with the physical limit to how fast information can be transported from, say on electron to another, so that if light traveled significantly faster or slower communication or something else would not function properly.

 

Indeed, one might ask the same thing about the other things such the speed of sound, or the wavelength of the color lemonchiffon. The world is full of set numbers, as per, for example, the periodic table.

 

Indeed, the anthropic principle asks why the physical constants are what they are, pointing out, like many a theologian, that if any one of several were any different, that the universe would not have existed, or would have not expanded, and certainly would not have provided the conditions for life to exist.

 

So perhaps we don't know the answer to the question, barring the rather circular answer provided by a theologian that God picked numbers our of 'thin air', or just saying that "it is what it is."

 

I tend to agree with those who suggest that the way that the periodic table "unfolds" is the only possible way that it could, much the same as stating that it is inevitable that irrational numbers will appear once one sets up a system of counting, or that any system will be be incomplete or have results unrelated to its basic axioms (as best as I can paraphrase Goedel).

 

Excuse my philosophizing, but I like Paul Valery's comment that "...the universe is a flaw in the purity of non-being" as if to suggest that they go together like love and marriage, so to speak. In the same sense, it seems to me that other things, such as the qualities of a hydrogen atom and two oxygen molecules. We can't always say why there is a limit to how fast sound goes, etc., but we can see that everything has to coexist in the same universe, and that the various speeds just reflect some kind of "pecking order" of the various forces, as Nietzche claims in the "Will to Power" when trying to discredit the literal belief in cause and effect.

Edited June 16, 2016 by disarray

[imatfaal]

 

With regards to the question as to why nothing can go faster than light, or, to be more precise, why is the speed of light 299,792,458 metres per second and not, for example, 4529553 m/s.

...

 

The speed of light flows from the fact that it is electromagnetic radiation propagating in wave form through a vacuum with a certain vacuum permeability (mu zero) and a certain vacuum permittivity (epsilon zero) - this combined with Maxwell's equations allow you to calculate the speed of light in a vacuum and shows that it must be invariant. It was from here that Einstein started

[michel123456]

 

 

Yes.

I don't understand.

If we replace the analogy with this one:

you have a flashlight that turns from red to green every second. Two flashlights. You send one of flashlights at the edge of the universe. When you observe your flashlight red, you know the other is green, and vice-versa.

So you make the experiment and at some instant you observe the flashlight indeed red. You know the other one is green. But even if you smash the light while being red, does that mean the other flashlight will stop flashing from one colour to the other? and stay on green? Or that the other light will "feel being smashed" ? As if they were one single object?

Edited June 16, 2016 by michel123456

[swansont]

I don't understand.

If we replace the analogy with this one:

you have a flashlight that turns from red to green every second. Two flashlights. You send one of flashlights at the edge of the universe. When you observe your flashlight red, you know the other is green, and vice-versa.

So you make the experiment and at some instant you observe the flashlight indeed red. You know the other one is green. But even if you smash the light while being red, does that mean the other flashlight will stop flashing from one colour to the other? and stay on green? Or that the other light will "feel being smashed" ? As if they were one single object?

 

 

You can't arbitrarily change the example, because the original example was about entangled states, and the new one is not.

 

I think that it is expecting too much to ask why it is at that particular speed, instead of, say a 100,000 metres faster of slower or whatever. Rather, I think a more fruitful question to ask

is why is their a limit to the speed at all.

 

That gets more into philosophy than physics. There has to be a value, though it could be infinite. It turns out that it's not. "Why" isn't something science readily addresses at the fundamental level. Science describes how nature behaves, not necessarily why it behaves that way.

[disarray]

Thanks Delta for the non higher-mathematics explanation, but I think that there is a danger of getting hung up on what one means by "information." Perhaps the first person is not sending hard-cold verbal-like information to the other person saying "I have a green card." But the explanation you give suggests that the contents of the second person's envelope's (the indeterminately colored or non-colored card) changes into being something with a definite color. So yes, I get it..the first card does not "cause" the second card to be one thing or another....yet at the same time we say that the second card had no color until we looked at the first one....(You can't have it both ways: either the second card had no definite color before we looked at the first one or else it did.) Don't we indeed 'cause' the first card to pick a color rather than just being indeterminate when we look at it, just as we cause an electron to "collapse" when we measure it in the double slit experiment? And If the second card had to definite color until we looked at the first, how can we say that there was no interaction between the two cards....whether or not we label such interaction as 'communication' or 'changing' or 'causing' or 'affecting' or 'exchanging information'?

 

And what do we literally mean by "looking" in the envelope...does this suggest that a photon is both wave and particle until someone looks at it with the naked eye, and then it becomes one or the other. (I gather that we mean we are using some sort of screen or instrument to "look at" [aka measure] an electrons behavior in the double-slit experiment). If so, can someone please tell me what might be happening in terms of the big picture: are humans causing zillions of electrons to collapse each second as they go about their business....are chemicals interacting in such a way all over the universe in such a way as to cause waves to collapse? What is going on here?

 

And has anyone really ever really had any clear idea as to what happens when a wave collapses? Bohr's interpretation of what happens in the double-slit experiment is often dismissed as saying nothing, because it seems to treat statistics as if it were an actual physical thing. Indeed, the Schrodinger equation implies "that we never deal directly with the quantum objects of the microscopic realm. We therefore need not worry about their physical reality, or their lack of it. An 'existence' that allows the calculation of their effects on our macroscopic instruments is enough for us to consider."

http://physics.about.com/od/quantuminterpretations/fl/What-Is-the-Copenhagen-Interpretation-of-Quantum-Mechanics.htm

 

So really, saying that the wave collapses, or other statistical possibilities about an electrons position disintegrate when we "look" at it, does not explain anything per se, (even though it can be described with great accuracy mathematically) and is perhaps not much better than invoking an explanation involving God.

Edited June 16, 2016 by disarray

[swansont]

 

So really, saying that the wave collapses, or other statistical possibilities about an electrons position disintegrate when we "look" at it, does not explain anything per se, (even though it can be described with great accuracy mathematically) and is perhaps not much better than invoking an explanation involving God.

 

 

 

If explanations involving God sufficed, science would not be necessary — if you are asking a question that science is supposed to answer. The "greater accuracy" is the part science does.

[disarray]

well, of course I know that "If explanations involving God sufficed, science would not be necessary." I'm just trying to make the point that we don't really know what happens or perhaps even what we mean when we say that there is a collapse. And yes, it is nice to gain accuracy. But my point is, I guess, that there doesn't seem to be much point in trying to discuss whether or not information is passed between one electron and another if we don't really have any idea what happens when a wave collapses.

Edited June 16, 2016 by disarray

[Strange]

 

So really, saying that the wave collapses, or other statistical possibilities about an electrons position disintegrate when we "look" at it, does not explain anything per se, (even though it can be described with great accuracy mathematically) and is perhaps not much better than invoking an explanation involving God.

 

Wavefunction collapse is just an interpretation (a metaphor, if you like) of what the mathematics says. There are many other interpretations (many worlds, transactional, etc) all of which are ways of describing or visualising what the mathematics says. They all describe the same theory and are thus indistinguishable by science. You can take your pick of whichever appeals to you.

https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics

 

 

And what do we literally mean by "looking" in the envelope...does this suggest that a photon is both wave and particle until someone looks at it with the naked eye, and then it becomes one or the other.

 

They are always both wave-like and particle-like. The idea that they switch between being particles and waves is another bit of bad journalism.

[TakenItSeriously]

why is the speed of light 299,792,458 metres per second and not, for example, 4529553 m/s.

 

If you're looking for significance in the number itself, such as finding a perfect number or a factor of pi or something, don't forget that the units are arbitrary so the literal number "299,792,458 m/s" is going to be arbitrary as well.

 

Who knows, if you based C on Planck units and analyzed the number, maybe something would reveal itself, unless it's already been done.

 

Imagine if a light year was the same number as a year in Plank units and no one ever bothered to check.

Edited June 16, 2016 by TakenItSeriously

[Strange]

Who knows, if you based C on Planck units and analyzed the number, maybe something would reveal itself, unless it's already been done.

 

In that case c=1.

[imatfaal]

If you're looking for significance in the number itself, such as finding a perfect number or a factor of pi or something, don't forget that the units are arbitrary so the literal number "299,792,458 m/s" is going to be arbitrary as well.

 

Who knows, if you based C on Planck units and analyzed the number, maybe something would reveal itself, unless it's already been done.

 

It is only the dimensionless constants that you might have any success with (you won't) - most commonly looked at is the fine structure constant alpha which is about 1/137

 

It has been a mystery ever since it was discovered more than fifty years ago, and all good theoretical physicists put this number up on their wall and worry about it.) Immediately you would like to know where this number for a coupling comes from: is it related to pi or perhaps to the base of natural logarithms? Nobody knows. It's one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man

 

 

Feynman in QED

[TakenItSeriously]

In that case c=1.

I cross edited something similar

[imatfaal]

...Imagine if a light year was the same number as a year in Plank units and no one ever bothered to check.

 

The ratio between distance travelled by light and the time taken is 1 in Planck units - so to an extent the above is true by definition; the top of the equation (distance in a lightyear) and bottom of the equation (time in a year) will be the same magnitude so that the ratio (ie speed of light) equals one

[disarray]

Strange: You write that "They are always both wave-like and particle-like. The idea that they switch between being particles and waves is another bit of bad journalism."

 

But doesn't the double slit experiment and the notion of wave collapse suggest that, depending upon the situation, a electron is or behaves very much more like a wave than a particle (and vice versa) suggest that it can shift gears so to speak....Could we say that the electron is neither particle or wave but rather is in neutral (gear) before measured, or, getting back to entanglement, can we say that the card is neither green nor red, but rather in neutral before someone looks in the envelope?

 

In any case, the event of looking at (measuring the state of) the card somehow affects it, does it not, and also apparently affects the state (aka spin, aka color) of the other card, which, like the first card, was, up until then neither red nor green, based on a comment on page 5 that everyone seemed to agree upon: 'The reason that the "spooky action at a distance" thing comes in, is that we know through other means that in the quantum realm neither "card" is in a definite state of being green or red until someone opens their envelop and checks the color.'

 

So I can't see how we can say that looking at the other card does not 'affect' (so yeh, let's say "transfer information" is too strong a phrase) the other one, but merely tells you about whether it is red or green, if the other card was neither until you looked at the first card.

[TakenItSeriously]

The ratio between distance travelled by light and the time taken is 1 in Planck units - so to an extent the above is true by definition; the top of the equation (distance in a lightyear) and bottom of the equation (time in a year) will be the same magnitude so that the ratio (ie speed of light) equals one

You're kidding! Wow, how is it that the linkage of space and time is still just a theory if that's the case?

 

Unless it's based on how plank units are derived. Like if plank distance was derived from plank time and C and perhaps make it a circular result?

 

Oh, wait, that's what you were saying at the beginning. Lol. I was thinking they were independently derived for some reason but that doesn't seem reasonable.

Edited June 16, 2016 by TakenItSeriously

[disarray]

Well, one might similarly ask why there is some particular number for a Planck unit of time or space? But yes, there conceivably might be some connection between such things as Planck units and the speed of light or whatever.

 

I think we can put the question in the "too hard" basket.

 

My point really was that there might be a reason if we were smart enough to figure it out, but more importantly, my point was that the laws are not only the same everywhere, but also that they are ineluctable....not just picked out of a hat at random, but rather couldn't be anything but what they are.

Edited June 16, 2016 by disarray

[swansont]

well, of course I know that "If explanations involving God sufficed, science would not be necessary." I'm just trying to make the point that we don't really know what happens or perhaps even what we mean when we say that there is a collapse. And yes, it is nice to gain accuracy. But my point is, I guess, that there doesn't seem to be much point in trying to discuss whether or not information is passed between one electron and another if we don't really have any idea what happens when a wave collapses.

 

 

My point is that the increase in accuracy is the whole point of science. As Strange has pointed out, the wave function collapse is an interpretation of QM, not QM itself. We don't know what's going on between the particles; all we can do is model what we think is going on and test that model. If we can't test it, we can't figure out what is happening. We can only go on the results. That's the limitation we have.

[michel123456]

 

With regards to the question as to why nothing can go faster than light, or, to be more precise, why is the speed of light 299,792,458 metres per second and not, for example, 4529553 m/s.

 

I think that it is expecting too much to ask why it is at that particular speed, instead of, say a 100,000 metres faster of slower or whatever. Rather, I think a more fruitful question to ask

is why is their a limit to the speed at all.

There is a logical explanation.

If there were no limit, a same object could be at 2 different places at the same time. That would be another universe.

[swansont]

You're kidding! Wow, how is it that the linkage of space and time is still just a theory if that's the case?

 

"Just a theory" is a red flag of a phrase in a science discussion. It suggests you don't understand what a theory is, in a scientific context. (it doesn't mean guess, it doesn't mean untested)

[Strange]

Strange: You write that "They are always both wave-like and particle-like. The idea that they switch between being particles and waves is another bit of bad journalism."

 

But doesn't the double slit experiment and the notion of wave collapse suggest that, depending upon the situation, a electron is or behaves very much more like a wave than a particle (and vice versa) suggest that it can shift gears so to speak....

 

The thing is, they have a number of properties some of which we (classically) associate with waves (such as wavelength or frequency) and some that we traditionally associate with particles (such as being indivisible, momentum*, etc). They are neither waves nor particles. They might look more like one or the other depending on which properties you are measuring.

 

*OK, not strictly true, but I was struggling for an example!

[swansont]

There is a logical explanation.

If there were no limit, a same object could be at 2 different places at the same time. That would be another universe.

 

In a Newtonian model this is not the case. I don't see how you arrive at your conclusion.

[Strange]

In any case, the event of looking at (measuring the state of) the card somehow affects it, does it not, and also apparently affects the state (aka spin, aka color) of the other card, which, like the first card, was, up until then neither red nor green, based on a comment on page 5 that everyone seemed to agree upon: 'The reason that the "spooky action at a distance" thing comes in, is that we know through other means that in the quantum realm neither "card" is in a definite state of being green or red until someone opens their envelop and checks the color.'

 

So I can't see how we can say that looking at the other card does not 'affect' (so yeh, let's say "transfer information" is too strong a phrase) the other one, but merely tells you about whether it is red or green, if the other card was neither until you looked at the first card.

 

The entangled particles are described by a single wave function, as such you can think of them as being a single "thing". When you observe that thing it makes the spin definite (and also stops it being a single thing - they are no longer entangled).

 

This entangled "thing" can be spread over half the universe, but that's OK because quantum effects are inherently non-local anyway (in time and space).

[michel123456]

 

In a Newtonian model this is not the case. I don't see how you arrive at your conclusion.

If I can reach infinite velocity, time to go from one point to another is null.

[TakenItSeriously]

Is that accurate? (the bold part in the above)

In the example of the cards in envelopes, I don't think it is literally true. Though to be fair, Delta did use the expression "taken at face value".

 

It would only be true if there were no way possible to determine the contents of the envelop through cheating, such as switching the envelopes with envelopes where the contents were known, but that would assume perfect security which doesn't exist.

 

We often think of it as being hypothetically true because if no one was cheating, then there would be no way to confirm or deny the contents and it would be an equivalent condition of being impossible to know, but you can never assume no one is cheating with absolute certainty either.

 

Which BTW, is why you should never use a scientist to debunk a con artist. They take for granted too many hypothetical conditions.

 

I keep thinking of the gamblers fallacy where if you flipped a fair coin a thousand times and it came up heads every time, the next flip should still be 50:50. But that's only the mathematician believing it's a fair coin because he was told to assume it was fair or it could be a fair coin but the coin flipper was using slight of hand to control the results. In any case, believing the result should be 50:50 after results showing heads a thousand times in a row, is clearly foolish reasoning.

Edited June 16, 2016 by TakenItSeriously

[swansont]

If I can reach infinite velocity, time to go from one point to another is null.

 

 

Yes, precisely. Information transfer would happen instantaneously, which is a viable solution. Other than nature doesn't happen to work that way.