Why can't you go faster than light

[JohnnyMalaria]

You are assigning a physical attribute to something that is virtual.

A spot isn't a tangible thing and you can't touch a shadow. You can touch the physical object that is being obscured from a light source.

Think what a spot is. It is the scattering of a very large number of photons from a surface (or interface between dissimilar materials) over a concentrated area and that propagate to an observer. A photon leaves the source, travels to the surface and the scattered photon reaches your eye. On a large enough timescale it seems as if the spot is continuous and moves when the light source moves. But if you turn the light source off, the spot disappears. Every time you observe the spot, it is a different set of photons. There's no connection between the spot at t=0 and t=something whether the light is on all the time or just for a fraction of the second at the beginning and end.

[tggzzz]

You are assigning a physical attribute to something that is virtual.

A spot isn't a tangible thing and you can't touch a shadow. You can touch the physical object that is being obscured from a light source.

You'll have to specify what you mean by "virtual" and "tangible" - and check whether you are using them in the same sense as other people.

You can't touch a rainbow, or brockenspectre, or a sun dog, or even the sky. Does that mean they don't exist?

Think what a spot is. It is the scattering of a very large number of photons from a surface (or interface between dissimilar materials) over a concentrated area and that propagate to an observer. A photon leaves the source, travels to the surface and the scattered photon reaches your eye. On a large enough timescale it seems as if the spot is continuous and moves when the light source moves. But if you turn the light source off, the spot disappears. Every time you observe the spot, it is a different set of photons. There's no connection between the spot at t=0 and t=something whether the light is on all the time or just for a fraction of the second at the beginning and end.

Irrelevant.

[JohnnyMalaria]

Irrelevant.

No it's not.

If you are male, have a full bladder, take a whiz outside and pee in one place, you'll get a puddle (unless you're standing over a drain or the edge of a cliff). If you point Percy at a different location, you'll get another puddle. If you wiggle your thingy back and forth then you'll see that the stream of water is actually a series of discrete droplets (single chamber choked flow atomization). If you do it fast enough then the puddle of water will seem to move fast - faster than it should. But each puddle is made by pee droplets emitted in that direction. How the first puddle came about has absolutely no relation with the second. There is no correlation. This is what's irrelevant.

Of course, in this experiment you'd have to be able to pee like a shire horse with tremendous velocity sitting on a merry-go-round and spinning at very high speed. 

(If you're not male then you are missing one of life's wondrous gifts )

[CopperCone]

can you help my dick started to glow blue after I conducted this experiment???

[JohnnyMalaria]

North Pole in January.

[tggzzz]

Irrelevant.

No it's not.

If you are male, have a full bladder, take a whiz outside and pee in one place, you'll get a puddle (unless you're standing over a drain or the edge of a cliff). If you point Percy at a different location, you'll get another puddle. If you wiggle your thingy back and forth then you'll see that the stream of water is actually a series of discrete droplets (single chamber choked flow atomization). If you do it fast enough then the puddle of water will seem to move fast - faster than it should. But each puddle is made by pee droplets emitted in that direction. How the first puddle came about has absolutely no relation with the second. There is no correlation. This is what's irrelevant.

Of course, in this experiment you'd have to be able to pee like a shire horse with tremendous velocity sitting on a merry-go-round and spinning at very high speed. 

(If you're not male then you are missing one of life's wondrous gifts )

Sigh.

You are confusing how fast the drops travel to their landing place (radial velocity) with how fast the landing place moves (tangential velocity).

The radial velocity is, of course, limited by the speed of light in a vacuum.

The tangental velocity is, of course, omega*r where omega is the angular velocity in radians/s, and r is the radius at which the drops land. Since r can be arbitrarily large, the tangental velocity can also be arbitrarily large.

[hamster_nz]

On deeper analysis you will find there is no one 'landing spot'... Each projectile has it's own landing spot determined at the time of release, and heads straight for it, following the laws of motion.

There is no 'tangental velocity'. All projectiles move straight away from the source unless under the influence on an external force.

The location of a landing spot is a position that is a function of time. If you measure the rate of change in position you might get a number greater than the speed of light, but nothing is actually moving that fast.

[tggzzz]

The location of a landing spot is a position that is a function of time. If you measure the rate of change in position you might get a number greater than the speed of light, but nothing is actually moving that fast.

That paragraph is internally contradictory.

[hamster_nz]

The location of a landing spot is a position that is a function of time. If you measure the rate of change in position you might get a number greater than the speed of light, but nothing is actually moving that fast.

That paragraph is internally contradictory.

Not at all.

Can you tell me what is the mass (or energy if you like) of the thing that might be moving at greater than the speed of light?  Does it have any momentum?

I think you will find it has zeo mass, zero energy and zero momentum. It is a nothing - so it can change position as fast as it wants.

[tggzzz]

The location of a landing spot is a position that is a function of time. If you measure the rate of change in position you might get a number greater than the speed of light, but nothing is actually moving that fast.

That paragraph is internally contradictory.

Not at all.

Can you tell me what is the mass (or energy if you like) of the thing that might be moving at greater than the speed of light?  Does it have any momentum?

I think you will find it has zeo mass, zero energy and zero momentum. It is a nothing - so it can change position as fast as it wants.

All that is correct[1] - but it isn't what you wrote!

Einstein didn't state that nothing can travel faster than the speed of light in a vacuum. He did state, to put it in loose modern terms, that you cannot convey information (i.e. particles, waves) faster than the speed of light in a vacuum.

Except, of course, that now measurements relating to quantum entanglement somewhat muddy the waters

[1] Except for the spot of light being "a nothing". Funny how people can and do use "nothings" to make physical measurements

[RoGeorge]

[apis]

Except, of course, that now measurements relating to quantum entanglement somewhat muddy the waters

Sadly no, you can't use entanglement to transmit information faster than the speed of light.

As you say the modern version of nothing travels faster than c is you can't send information faster than c, where c is a physical constant that happens to be equal to the speed of light in vacuum.

[NiHaoMike]

No it's not.

If you are male, have a full bladder, take a whiz outside and pee in one place, you'll get a puddle (unless you're standing over a drain or the edge of a cliff). If you point Percy at a different location, you'll get another puddle. If you wiggle your thingy back and forth then you'll see that the stream of water is actually a series of discrete droplets (single chamber choked flow atomization). If you do it fast enough then the puddle of water will seem to move fast - faster than it should. But each puddle is made by pee droplets emitted in that direction. How the first puddle came about has absolutely no relation with the second. There is no correlation. This is what's irrelevant.

Of course, in this experiment you'd have to be able to pee like a shire horse with tremendous velocity sitting on a merry-go-round and spinning at very high speed. 

(If you're not male then you are missing one of life's wondrous gifts )

Why can't a girl do it?

[Homer J Simpson]

[Vtile]

https://youtu.be/14ToSwTAgT4

QED 

[RandallMcRee]

The spot isn't moving because it doesn't exist.

Nobody can argue with you or make you change your mind, here: you do not understand the english language the same as the rest of the respondents and readers.

Normally, when you say something does not exist that literally means it cannot be perceived. But obviously the moving spot is perceptual. So what *you* say does not make sense to the rest of us!

Think back to the light beam being traced out by the CRT on an analog scope. Folks have already established that no law of physics is broken by a faster than light moving beam. This beam hits the CRT and causes some of its particles to glow. Those particles are not themselves traveling! They just glow in response to the beam. So, very cleverly, we see the path of the beam, travelling at (perhaps) faster than light, using particles (CRT) that are not travelling at all. Our clever ancestors.

Make sense?

[CatalinaWOW]

No it's not.

If you are male, have a full bladder, take a whiz outside and pee in one place, you'll get a puddle (unless you're standing over a drain or the edge of a cliff). If you point Percy at a different location, you'll get another puddle. If you wiggle your thingy back and forth then you'll see that the stream of water is actually a series of discrete droplets (single chamber choked flow atomization). If you do it fast enough then the puddle of water will seem to move fast - faster than it should. But each puddle is made by pee droplets emitted in that direction. How the first puddle came about has absolutely no relation with the second. There is no correlation. This is what's irrelevant.

Of course, in this experiment you'd have to be able to pee like a shire horse with tremendous velocity sitting on a merry-go-round and spinning at very high speed. 

(If you're not male then you are missing one of life's wondrous gifts )

Why can't a girl do it?

She can.  But her aiming apparatus is not as flexible.

[Brumby]

A spotlight, laser, scope trace, etc. does not consist of anything moving in a lateral direction.  In fact, there IS no movement of anything visible in a lateral direction at all.

What is being observed is a series of photons which emanate from different locations at different times.  The distance between any two locations and the time between emissions from those two locations do not combine to create a velocity of any single element of the system.  Anything of this sort being called "motion" is perceived motion - exactly the same as we see every day on television.

[tggzzz]

Anything of this sort being called "motion" is perceived motion

And with that we enter the realm of philosophy, not physics.

[cncjerry]

The inverse of the laser on the moon is looking from one side to the other by turning your head.  Or pointing your willie at one side of the moon then the other, depending on if you have one.  So I have proven that only men can exceed the speed of light with their genitals.

[RoGeorge]

The only problem will be the length: shrinks to zero when approaching the speed of light.
 

[Rick Law]

The only problem will be the length: shrinks to zero when approaching the speed of light.
 

You cannot shrink length gradually to zero.  Length is quantized.  The smallest length measurement is called a Plank Length which is ~1.62x10E-35 meter.  So you can shrink length one quantum (a Plank Length) at a time but you cannot shrinking it in smaller increments.

[JohnnyMalaria]

Think back to the light beam being traced out by the CRT on an analog scope. Folks have already established that no law of physics is broken by a faster than light moving beam. This beam hits the CRT and causes some of its particles to glow. Those particles are not themselves traveling! They just glow in response to the beam. So, very cleverly, we see the path of the beam, travelling at (perhaps) faster than light, using particles (CRT) that are not travelling at all. Our clever ancestors.

Make sense?

No. That's just pure nonsense.

And, as a native of England living in the US, I sleep comfortably at night knowing that the inability to comprehend the language lies with its adopters, not its creators.

Heaven help us all if we get on to the Twin Paradox.

[German_EE]

"Only two things travel faster than light, gossip and starships named Enterprise"

Leonard McCoy MD

[Mr. Scram]

Nice video, except it doesn't cover the "Why" part from its title. 

It does briefly, but the title is fairly clickbaity.