We Can't Measure the Speed of Light

[Grumblenuts]

According to Veritasium anyway:




A thoughtful, rigorous, compelling presentation. Watch the whole thing.. But is he right? He quotes Einstein pompously describing this notion as,

neither a supposition, nor a hypothesis about the physical nature of light, but a stipulation about the nature of light that I can make of my own free will to arrive at the definition of simultaneity.

and finishes up, waxing philosophically:

So if we can never measure the speed of light, and it makes no difference, to any of the laws of physics, then what's the point in even talking about it? Well, that is certainly one valid perspective in a debate that has been ongoing since 1905. Some physicists appeal to Occam's razor. Isn't it just simpler if light travels at the same speed? Most working physicists just accept the convention and move on with their lives, but I think it's important to point out that it is just a convention, not an empirically verified fact.

Personally, I find it fascinating that this is something about the universe that is hidden from us. Sure, the round trip speed of light is 'c', but does the one way speed even have a well-defined value? And if it doesn't, what does that mean for the concept of simultaneity? When is right now on Mars? Does it even make sense to talk about things happening at the same time if they're separated by distance? Y'know maybe this is an odd quirk of the universe and there's no good reason for it or maybe, when physics takes the next paradigmatic leap, our inability to measure the one way speed of light will be the obvious clue to the way General Relativity, Quantum Mechanics, space and time are all connected. And we'll wonder why we didn't see it before.

Or perhaps why we didn't just listen to Nikola Tesla in the first place. Of course, I have tons to respond with, but what I'd really like to know is whether others disagree with any of this or, like me, disagree with it entirely?

 

[Fort Fun Indiana]

According to Veritasium anyway:




A thoughtful, rigorous, compelling presentation. Watch the whole thing.. But is he right? He quotes Einstein pompously describing this notion as,

and finishes up, waxing philosophically:

Or perhaps why we didn't just listen to Nikola Tesla in the first place. Of course, I have tons to respond with, but what I'd really like to know is whether others disagree with any of this or, like me, disagree with it entirely?

I have heard this before. Technically accurate. There are limits on our accuracy of measuring anything at all. There isn't anyone out there NOT rounding off pi.

 

[Fort Fun Indiana]

According to Veritasium anyway:




A thoughtful, rigorous, compelling presentation. Watch the whole thing.. But is he right? He quotes Einstein pompously describing this notion as,

and finishes up, waxing philosophically:

Or perhaps why we didn't just listen to Nikola Tesla in the first place. Of course, I have tons to respond with, but what I'd really like to know is whether others disagree with any of this or, like me, disagree with it entirely?

"Simulteneity" is a construct. Like, a sphere, or a straight line.

 

[Grumblenuts]

There are limits on our accuracy of measuring anything at all.

I don't find any of this to be about that.

"Simulteneity" is a construct. Like, a sphere, or a straight line.

"a stipulation about the nature of light that I can make of my own free will to arrive at the definition of simultaneity."

 

[Fort Fun Indiana]

I don't find any of this to be about that.

"a stipulation about the nature of light that I can make of my own free will to arrive at the definition of simultaneity."

A sphere is also well defined .

As for accuracy of measurements:

No, this specific discussion of the speed of light is not about that general idea. But it fits into it nicely

 

[Grumblenuts]

Fair enough.

 

[JoeMoma]

It is possible that everything that we think we perceive isn't real because we are living in a simulation like The Matrix Movies.

 

[Fort Fun Indiana]

Fair enough.

"The universe is under no obligation to make sense to us."

 

[Grumblenuts]

It is possible that everything that we think we perceive isn't real because we are living in a simulation like The Matrix Movies.

Yeah, of course anything we seemingly can't disprove may be presumed possible, but I generally don't take fictional notions seriously just because they're clearly crafty or popular, do you? We used to say the Moon was made of green cheese. The absurd can certainly prove entertaining without implying a basis in reality. Art for art's sake. That said, use of a matrix or a space filling web analogy may help people better comprehend fundamental terms like "field" and "pressure."

If you entirely agree with Veritasium and wish to express that, by all means, be my guest. But,
again, what I'd really like to know and discuss here is What do you disagree with him about? and Why?

 

[Grumblenuts]

For example:

I disagree that measuring the (one way) speed of light is impossible.. in the senses that it's obviously long been done, scientifically, and with increasing accuracy. Of course, stating that also requires disagreeing with him (and Einstein) about being uncertain that dividing a perfectly reflected (two way) measurement by two can be relied upon to provide the only meaningful or logical result each way, given neither moves significantly in relativistic relation to the other. And even if relative movement is a significant consideration, that too simply calls for mathematical correction, not presuming any rate from zero to 2c is equally likely if even possible.

However,.. I do agree that measuring "the speed of light" is impossible.. but for entirely different reason. Light actually goes nowhere. It has no speed. We never observe the source "light" itself. We can only detect the EM energy that the medium transfers to us through itself. Even that must be a reflection for our eyes / brains to visualize it as colors. We would actually see very little if we could survive in space with no helmet or anything else between us and the Sun. Just what little passively reflects off its gaseous exterior. Other stars would be dim as well. Close planets and moons would seem unnaturally bright though and looking directly at the Sun's energy would quietly destroy our vision in no time, given the cold and vacuum conditions hadn't destroyed it first.

 

[JoeMoma]

Yeah, of course anything we seemingly can't disprove may be presumed possible, but I generally don't take fictional notions seriously just because they're clearly crafty or popular, do you? We used to say the Moon was made of green cheese. The absurd can certainly prove entertaining without implying a basis in reality. Art for art's sake. That said, use of a matrix or a space filling web analogy may help people better comprehend fundamental terms like "field" and "pressure."

If you entirely agree with Veritasium and wish to express that, by all means, be my guest. But,
again, what I'd really like to know and discuss here is What do you disagree with him about? and Why?

There is no logical reason we should expect light to have a speed of c/2 in one direction and infinite speed in the opposite direction either. It is just as fictional as living in "The Matrix".

 

[Grumblenuts]

There is no logical reason we should expect light to have a speed of c/2 in one direction and infinite speed in the opposite direction either. It is just as fictional as living in "The Matrix".

Yeah, I doubt even Einstein would agree with Veritasium on much of this. He seemed pretty convinced that c is a constant.

Einstein concluded that simultaneity is not absolute, or in other words, that simultaneous events as seen by one observer could occur at different times from the perspective of another. It's not lightspeed that changes, he realized, but time itself that is relative. Time moves differently for objects in motion than for objects at rest. Meanwhile, the speed of light, as observed by anyone anywhere in the universe, moving or not moving, is always the same.

(c + c) / 2 = c
(c/2 + ∞) / 2 = ?
(2c + ∞) / 2 = ?
2c = ?