/sci/ - Science & Math » Thread #13181959

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Do lenses do work?

Anonymous Mon 24 May 17:51:37 2021 No.13181959 View Reply Original Report

Quoted By: >>13181991 >>13182147 >>13182185 >>13182195 >>13182200 >>13182324

Because a photon traveling through a lens changes direction, so mustn't there be a force to cause the change in direction, and work done as a result??

Anonymous

Anonymous Mon 24 May 2021 17:52:56 No.13181970 Report

Quoted By: >>13182127 >>13182185 >>13182384

Also what is the force acting on the particle??

Anonymous

Anonymous Mon 24 May 2021 17:57:03 No.13181991 Report

Quoted By: >>13182027 >>13182100 >>13182120 >>13182559

>>13181959
>so mustn't there be a force to cause the change in direction, and work done as a result
dont think in terms of energy, think in terms of momentum. if the lens bends the photon down, the lens will be pushed up (by a miniscule amount)

>a photon traveling through a lens
photons dont quite "travel through" a lens, nobody fully understands what the fuck happens to a photon as it goes "through" a medium

Anonymous

Anonymous Mon 24 May 2021 18:03:19 No.13182027 Report

Quoted By:

>>13181991
huh, okay ye that makes sense, so like an inertial force or something?

Anonymous

Anonymous Mon 24 May 2021 18:12:46 No.13182100 Report

Quoted By: >>13182120

>>13181991
>nobody fully understands what the fuck happens to a photon as it goes "through" a medium
Relativity is the most tested theory in the history of science but physicists can't explain refraction, kek.

Anonymous

Anonymous Mon 24 May 2021 18:16:59 No.13182120 Report

Quoted By: >>13182221 >>13182382

>>13181991
>>13182100
https://www.youtube.com/watch?v=NLmpNM0sgYk

Anonymous

Anonymous Mon 24 May 2021 18:17:31 No.13182127 Report

Quoted By: >>13182711

>>13181970
Gravity. It's instantaneous. It accounts perfectly for the motions of planets (including the so-called "anomalous" precession of Mercury) and would account for every observed behavior of photons around matter. Physicists get triggered if you point this out though.

Anonymous

Anonymous Mon 24 May 2021 18:21:10 No.13182147 Report

Quoted By: >>13182172

>>13181959
Yes there is force according to some basic physical models. Consider that light is an electromagnetic wave and the glass is a dielectric. The electric field will induce an electric charge on which the wave will exert a force.

Anonymous

Anonymous Mon 24 May 2021 18:25:31 No.13182172 Report

Quoted By: >>13182196

>>13182147
what about water
water isn't dielectric

Anonymous

Anonymous Mon 24 May 2021 18:27:22 No.13182185 Report

Quoted By: >>13182221

>>13181959
No, the energy of the light coming into and out of the lens is the same. Net work is zero.

>>13181970
Electromagnetic. Pretty much all conventional phenomena you encounter can be explained by some implementation of electromagnetic interactions, with the exception of gravity.

Anonymous

Anonymous Mon 24 May 2021 18:29:08 No.13182195 Report

Quoted By: >>13182204 >>13182208

>>13181959
A photon can't change directions at all, ever, because this would require it to change velocity. And as we all know, the velocity of light is constant.

Refraction doesn't exist. Don't overthink it, kid. Stop asking inconvenient questions.

Anonymous

Anonymous Mon 24 May 2021 18:29:15 No.13182196 Report

Quoted By: >>13182203

>>13182172
Water is dielectric. Hugely dielectric, the dielectric constant is about 80.

Anonymous

Anonymous Mon 24 May 2021 18:29:37 No.13182200 Report

Quoted By: >>13182292

>>13181959
The photon doesn't pass through the lens and bend, it is absorbed and remitted by the atoms in the lens. There is recoil against the atoms due to conservation of momentum.

Anonymous

Anonymous Mon 24 May 2021 18:30:05 No.13182203 Report

Quoted By: >>13182222 >>13182234

>>13182196
What about water that isn't pure?

Anonymous

Anonymous Mon 24 May 2021 18:30:11 No.13182204 Report

Quoted By: >>13184000

>>13182195
kek are you the dark matter guy?

Anonymous

Anonymous Mon 24 May 2021 18:30:40 No.13182208 Report

Quoted By:

>>13182195
>And as we all know, the velocity of light is constant
False

Anonymous

Anonymous Mon 24 May 2021 18:33:12 No.13182221 Report

Quoted By: >>13182228 >>13182238 >>13182926

>>13182120
>>13182185
>Pretty much all conventional phenomena you encounter can be explained by some implementation of electromagnetic interactions

How much force does an electric field exert on a photon, again? What's the formula?

Anonymous

Anonymous Mon 24 May 2021 18:33:26 No.13182222 Report

Quoted By:

>>13182203
you mean like pee?

Anonymous

Anonymous Mon 24 May 2021 18:34:28 No.13182228 Report

Quoted By: >>13182239

>>13182221
it was maxwell's equations, did you even watch the video?

Anonymous

Anonymous Mon 24 May 2021 18:36:20 No.13182234 Report

Quoted By:

>>13182203
Dont know. I assume the dielectric constant changes by adding salt or sugar.

Anonymous

Anonymous Mon 24 May 2021 18:37:21 No.13182238 Report

Quoted By:

>>13182221
Electric field exerts a force on the electrons of the glass.

Anonymous

Anonymous Mon 24 May 2021 18:37:23 No.13182239 Report

Quoted By: >>13182255 >>13182264 >>13182347

>>13182228
I did. I have some follow-up questions:

What's the charge of a photon?

What's the formula for the force exerted on a photon in an electric field? Just give me the formula.

Anonymous

Anonymous Mon 24 May 2021 18:40:34 No.13182255 Report

Quoted By: >>13182280

>>13182239
Photon has no charge. Photon has an associated electric field. The force is the electric field x the electron charge

Anonymous

Anonymous Mon 24 May 2021 18:43:10 No.13182264 Report

Quoted By: >>13182286

>>13182239
how the fuck would I know that shit you goddamn dildo

Anonymous

Anonymous Mon 24 May 2021 18:47:25 No.13182280 Report

Quoted By: >>13182603

>>13182255
Ok, so you're saying

F_photon = e*E

Is that your final answer?

Anonymous

Anonymous Mon 24 May 2021 18:48:38 No.13182286 Report

Quoted By:

>>13182264
I want answers motherfucker. Give me the formula.

Anonymous

Anonymous Mon 24 May 2021 18:50:35 No.13182292 Report

Quoted By: >>13182309 >>13182317

>>13182200
Why is it always remitted in precisely the correct direction? Why does the direction change between mediums?

Anonymous

Anonymous Mon 24 May 2021 18:54:18 No.13182309 Report

Quoted By: >>13182317

>>13182292
There is a probability of it being emitted in all directions, which you can get as the phase of the action. Integrate all phases from the photon traveling all paths and you get the distribution of where the photon could go. Take the typical classical limits and you'll recover what is observed to a high degree of accuracy. It's not guaranteed, just highly probable from quantum mechanics

Anonymous

Anonymous Mon 24 May 2021 18:55:52 No.13182317 Report

Quoted By:

>>13182292
>>13182309
https://en.m.wikipedia.org/wiki/Path_integral_formulation
If you wanted to read more into it

Anonymous

Anonymous Mon 24 May 2021 18:57:41 No.13182324 Report

Quoted By: >>13182528

>>13181959
If the speed of light is constant, and speed = wavelength*frequency, how come the wavelength of light in glass is shorter, but the color doesn't change?

If the frequency changes, then since energy = planck's constant * frequency, then light loses energy when it enters glass. If that's the case, how does it regain its original wavelength when it leaves? Where's the new energy coming from?

Anonymous

Anonymous Mon 24 May 2021 19:01:25 No.13182347 Report

Quoted By: >>13182365

>>13182239
Photons have zero charge. Electric and magnetic fields do not exert a force on photons for the same reasons photons don't interact with each other (at least in the classical domain).
https://en.wikipedia.org/wiki/Superposition_principle

Anonymous

Anonymous Mon 24 May 2021 19:06:24 No.13182365 Report

Quoted By: >>13182430

>>13182347
Oh OK so the formula is

F_photon = 0

If that's the case, what causes the photon to change directions? If it changes directions then it must change momentum since p=m*v. And if it changes momentum then there must be a force since F = dp/dt. But if F=0 then how does it change directions?

Anonymous

Anonymous Mon 24 May 2021 19:13:41 No.13182382 Report

Quoted By: >>13182892

>>13182120
of course a wave bends when the medium changes. the question is what the fuck happens to a photon

Anonymous

Anonymous Mon 24 May 2021 19:14:27 No.13182384 Report

Quoted By:

>>13181970
Hey, I know! Maybe the glass is actually bending spacetime so the photon is actually not moving at all but only appears to change direction and slow down. Yeah, that makes sense! Can anyone who knows general relativity chime in and explain this?

Anonymous

Anonymous Mon 24 May 2021 19:24:35 No.13182430 Report

Quoted By: >>13182494 >>13182511

>>13182365
A photon is an oscillation in the EM field. You can't change its direction. When incident upon a charged particle such as an electron in glass, the electron will oscillate with the photon, creating a new oscillation in the EM field. This oscillation interferes with the original photon, creating a perceived change of direction. Refraction does impart momentum (for example in optical tweezers), but the underlying reason is more complicated than "it just changes direction."

Anonymous

Anonymous Mon 24 May 2021 19:39:20 No.13182494 Report

Quoted By: >>13182531 >>13182536

>>13182430
So the photon never changes direction?

If no force is exerted on the photon, then why is there a force on the electrons?

Furthermore, let's say the photon travels through 100 miles of glass. At the end of the trip, the actual photon will be over a mile away from the electrons that appear to be photons, correct? How do they effect electrons miles away? And why don't we observe the photons to exit the glass along their original trajectory then?

Anonymous

Anonymous Mon 24 May 2021 19:44:44 No.13182511 Report

Quoted By:

>>13182430
perceived change of direction is change of direction

Anonymous

Anonymous Mon 24 May 2021 19:48:24 No.13182528 Report

Quoted By: >>13182543 >>13182744

>>13182324
>If the speed of light is constant
in a vacuum
the speed of light in a medium is slower

Anonymous

Anonymous Mon 24 May 2021 19:48:59 No.13182531 Report

Quoted By: >>13182554

>>13182494
>the electrons that appear to be photons
wut?

Anonymous

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Anonymous Mon 24 May 2021 19:49:54 No.13182536 Report

Quoted By: >>13182554

>>13182494
In other words, how does that explain the lateral displacement in picrel if the photon trajectory never changes?

Anonymous

Anonymous Mon 24 May 2021 19:51:38 No.13182543 Report

Quoted By:

>>13182528
But that violates special relativity! Say it ain't so anon. Was Einstein wrong? What about Michelson-Morley?

Anonymous

Anonymous Mon 24 May 2021 19:53:21 No.13182554 Report

Quoted By:

>>13182531
How do we explain lateral displacement if the photon trajectory never changes? >>13182536

Anonymous

Anonymous Mon 24 May 2021 19:54:04 No.13182559 Report

Quoted By: >>13182570

>>13181991
It was my understanding that the photon is absorbed by the particle as energy and then, dependant on the makeup of the particle, expelled again as energy, whether it be heat, light, sound, etc. Elementary particles themselves are just complex photon interactions, so it stands to reason that the addition of more photons causes currently not understood photonic interactions on a sub-particle level, up to and including the rearrangement or dissolution of the particle

Anonymous

Anonymous Mon 24 May 2021 19:56:32 No.13182570 Report

Quoted By: >>13182610 >>13182637

>>13182559
>currently not understood
Wait, so modern physics can't explain refraction? I thought this stuff was settled a hundred years ago.

Anonymous

Anonymous Mon 24 May 2021 20:02:57 No.13182603 Report

Quoted By: >>13182657

>>13182280
Yes

Anonymous

Anonymous Mon 24 May 2021 20:04:31 No.13182610 Report

Quoted By:

>>13182570
It is understood. Some posters are ignorant and project their ignorance.

Anonymous

Anonymous Mon 24 May 2021 20:10:00 No.13182637 Report

Quoted By: >>13182664

>>13182570
It was first explained in the 19th century in terms of electrical forces. The photon is an electric field and matter has electric charges so thats causes a force. Also the movement of electrical charges generates electric waves so thats how new waves are created, which you see as a change of direction.

Anonymous

Anonymous Mon 24 May 2021 20:14:19 No.13182657 Report

Quoted By: >>13182672 >>13182678 >>13182721

>>13182603
So photons have the same charge as electrons?

Anonymous

Anonymous Mon 24 May 2021 20:15:30 No.13182664 Report

Quoted By: >>13182712

>>13182637
so why doesn't light unbend after it passes through a prism

Anonymous

Anonymous Mon 24 May 2021 20:17:33 No.13182672 Report

Quoted By: >>13182696

>>13182657
Photons aren't real, they're just a convenience for measuring EM waves

Anonymous

Anonymous Mon 24 May 2021 20:18:34 No.13182678 Report

Quoted By: >>13182686

>>13182657
The light that comes out isnt the same light that went in

Anonymous

Anonymous Mon 24 May 2021 20:19:40 No.13182686 Report

Quoted By:

>>13182678
>this is what relatards believe

Anonymous

Anonymous Mon 24 May 2021 20:22:09 No.13182696 Report

Quoted By:

>>13182672
wtf XD you retard

Anonymous

Anonymous Mon 24 May 2021 20:24:46 No.13182711 Report

Quoted By: >>13182717

>>13182127
>Gravity. It's instantaneous.
bullshit
then how do people see properly in space?

Anonymous

Anonymous Mon 24 May 2021 20:25:14 No.13182712 Report

Quoted By:

>>13182664
Im not going to post a book on electromagnetism here. You already got the basic information several times.

Anonymous

Anonymous Mon 24 May 2021 20:26:00 No.13182717 Report

Quoted By: >>13182729

>>13182711
This may shock you but gravity still exists in space

Anonymous

Anonymous Mon 24 May 2021 20:26:34 No.13182721 Report

Quoted By:

>>13182657
No retard. I hate you. I already explained you this, this is like a troll comic routine from abbot and costello.

Anonymous

Anonymous Mon 24 May 2021 20:28:16 No.13182729 Report

Quoted By:

>>13182717
but way weaker than right next to big mass like a planet
so if the gravity was the cause, eye lenses would work differently depending on the gravity force

Anonymous

Anonymous Mon 24 May 2021 20:31:21 No.13182744 Report

Quoted By: >>13183284

>>13182528
the speed of light in a medium is still constant brainlet

Anonymous

Anonymous Mon 24 May 2021 21:04:39 No.13182892 Report

Quoted By:

>>13182382
you didn't watch the video did you

Anonymous

Anonymous Mon 24 May 2021 21:13:10 No.13182926 Report

Quoted By:

>>13182221
Photons ARE electric (and magnetic) fields.

Anonymous

Anonymous Mon 24 May 2021 22:22:53 No.13183252 Report

Quoted By: >>13183263

so how do you calculate the work done then?
Im waiting nerds

Anonymous

Anonymous Mon 24 May 2021 22:23:55 No.13183263 Report

Quoted By:

>>13183252
shine a known amount of photons through a given lens and measure how much warmer it gets, duh

Anonymous

Anonymous Mon 24 May 2021 22:26:54 No.13183284 Report

Quoted By:

>>13182744
depends on the medium
https://en.wikipedia.org/wiki/Graded-index_fiber

Anonymous

Anonymous Tue 25 May 2021 00:58:37 No.13184000 Report

Quoted By:

>>13182204
Who's the dark matter guy?

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