Why Does Light REALLY Bend?
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- Опубликовано: 12 дек 2019
- A lot of optical illusions can be explained by Fermat's principle of least time, but why does light obey it? On a fundamental level, it all comes down to quantum mechanics, specifically quantum optics, where we use the famous "Feynman path integral formulation" to explain light through photons.
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*Clarification:* In my quantum animations, that is not multiple photons taking different paths. It is a _single photon_ taking multiple paths simultaneously. We're releasing only one photon at a time. Adding those phasor arrows together gives us the _probability_ of receiving a single photon at any given moment.
*Minor Correction:* I show the paths leaving the source at the same time and arriving at the detector at different times, when it should actually be the other way around. Paths that take more time should be leaving the source earlier in order to arrive at the detector at the same time as the others. The reason we can add the phasor arrows together is because the paths arrive at the detector at the same time.
Still confused. Doesn't single photon imply that all paths "left" the detector at the same time?
@@ewthmatth No, because we don't actually know when it left the laser. All we _really_ know is when it _arrived_ at the detector.
The Science Asylum
Photon arrives all at once.
Potentially took all the paths.
It could have left at different times, because it arrives all at once...
Is there a way to detect when it left?
Or if it left at the same time, as well...
Can a photon move at C relative to another photon?
Wait, it was one photon...
F*ckit, quantum particles are f*cky AF.
How can laser light take multiple paths? I thought photons from a laser were meant to all be in phase... which would mean they all travel in the same direction...?
@@EternalSilverDragon In quantum even the laser pointed at a vacuum will have uncertainities
Richard Feynman could explain better than i can
Yoooooo plot twist “that’s just a lens” mind absolutely blown
totally.
I was literally like "shit son..."
Absolutely !!
Nice black hole animation too!
Absolutely what I was gonna say. Amazing explanation.
this comment was at the top of the comment section so i accidentally read it before that part... and it still got me
WOW
Just before the lens was revealed, I thought "add different pieces of glass to adjust the travel time for each ray sound like what a lens does", and oh boy, thank you for making me feel smart. ;)
Disruptive Times That is actually smart, not just a feeling. Don’t doubt your own abilities.
Thats Fresnel!
There is something going on here aside from physics. It's Nick's ability to teach. NEVER in my life have I learned as much so easily.
❤️
Same
Super talented!
"We just used quantum mechanics to explain how lenses work"
Me: happiness noise
What about magnets, though?
That actually exploded my mind. The way he presented the whole thing didn't even make me see it coming till he dropped it on me
@@klaik30 Surprise! 🤯
*happiness noises intensifies*
The Science Asylum if a lens works as per your animation then in a real lens why do the photons at the top are refracted to the bottom and bottom to the top, resulting in an inverted image, what does this have to do with the time it takes light to pass through glass to get to a sensor, that doesn’t explain how a lens works!
More of these "quantum mechanics explains macro scale phenomena" please. these are by far my favorite things to learn
Yes
Science becomes an elaborate piece of art in this channel.
elaborate, yet accessible
Why don't they teach us this quantum mechanical way it makes more sense then the classical way? Also I liked the video a lot it was very informative!
Because they're afraid people won't believe it ...and, judging from the comments I get on videos like this, I don't know that they're wrong.
I wouldn't agree on that "they" are afraid that noone would _believe_ it. I think most people are just not prepared enough to _understand_ it (even if they wanted). I mean, just talking about statistics, probabilities and Boolean algebra is way too complicated for most people. And then you are trying to explain reality using all that fancy stuff. No way! 😉
@@ScienceAsylum in the current political climate, it's difficult for me to imagine that a sizeable proportion of the US would not believe anything.
Also, not all science teachers have the same depth and breadth of knowledge. I would go as far as to say that the teacher you get itself follows a bit of a probability curve, one that is generally not weighted in the student's favor. This was never apparent to me growing up, but now in my 50's as an engineer and programmer looking back, I can easily pick out which of my teachers were actually good and which were simply well-meaning.
What this means is that for those teachers able to connect advanced concepts to simple every-day life, being able to use these advanced concepts in an explanation probably (ha) requires additional hands-on proof (which this channel does very well), like removing portions of the mirror in the mirror video for example, to get students to really understand that some/many of these advanced concepts are actually happening in reality and not just convenient mathematical constructs.
-Matt
@@deinfreund Fair point.
Nick you are appreciated by SO many people. I can’t think of another presenter that has the skills, gift for explaining, sense of humor, clean & clear production visuals, pure science chops, and all in a concise format. You represent the best of what RUclips has to offer. You deserve to be rewarded!
I liked how the black hole "detector" got bigger with each photon. Nice touch.
Thanks 🤓 Attention to detail is very important to me.
I'll never be tired of saying that this is the best scientific channel of RUclips. Your ability to give us deep insight of complex topic is amazing. Every time I whatch one of your videos I can really feel the wonder. Thanks!
Working of lens gave full satisfaction.
Optical Illusions and Quantum Mechanics?
never clicked faster
Same
In other words, you've just followed the least time path to this video
Fast fast
@@skatiruas fermat's principle at play
Or Quantum Illusions and Optical Mechanics. Or Optical Quantum and Illusion Mechanics. Choose one :P
You sir... are shattering one of life's mysteries at a time. And this is mindblowing and wonderful as heaven. Thanks for your work!!!
That was a real eye opener 35 years after finishing my education :) It made me finally fully grasp the concept and workings of Feynman's path integrals. Nice one!
When you think you understand optics, and QM has to throw yet another wrench in the works.
QM is something else
Mind blown at 7:54
Optics is by no means a closed field
We have macro approximations which are good enough for everyday uses of lenses in eyeglasses and telescopes, binoculars and microscopes
However, optics does allow us to trap light in quantum mechanics
It's not really a "wrench", as in even classical optics can also explain the same results, only in a different way. If we assume light is a wave, and that this wave has a continuous value at every point in space, we can still prove stuff like this.
I know I already said it in an earlier video, but still:
I really enjoy the "gradually going deeper into it" style. I bet you'd make a great physics teacher, one who would give at least a few in their class such a good time they'd think about making it their career. But on the other hand: with RUclips, you have a greater audience.
I _was_ a physics teacher for over a decade. RUclips is much better. It's more fun, it has better hours, more reasonable work-life balance, and I can connect with more people.
@@ScienceAsylum Yeah, it's a shame how society treats teachers, the people in charge of the future of our children.
But I am happy to read that you enjoy what you do, and that it has its perks.
@@ScienceAsylum And you don't have to grade tests.
people are gonna start accusing me of being a "fan" of yours... but I'll risk it. Another great video.
Zac, you fan you ! Let's just hope the shit does not hit the fan now that you made your coming out :)
Honestly dude, you have the phenomenal gift of communication. Your videos are literally the only (besides pbs spacetime which can sometimes be too dry...) creator on youtube who is both engaging and educational. I get tired of the same old repeated phrases and thought experiments tossed around the physics and QM world...you always have an original analogy to explain various phenomena which is neither dumbed down nor so advanced its inaccessible.
every time you pop up in my feed with a new video it addresses a new scientific question hardly any other similar channel would adress, and I love u for that man! I absolutely love your videos you are doing a great service to thousands of people and you probably are not even aware of the tremendous impact you have on some of your viewers. Respect!
Thanks! 😊
Same here. I just subscribed. Keep on making that great content.
Brilliant. OK, now *this* one is the best one ever. Seriously. It would be helpful if you had just one "best one ever" so I can find other comments to write, but in the meantime, this is definitely the best one ever. One of the other commenters wrote that this is how quantum mechanics and even classical physics should be taught. I think you could teach this to first graders the way you explained it and they would have a better handle on this than they would on classical physics, because this makes sense! Really well done!
J G +1
Great channel.
You're getting into some good topics recently and explaining them in a very graspable way.
I can see that a lot of thought goes behind your videos.
Great job, looking forward to more!
*Every time i see a video of yours, i always end with the mouth full open about what you have just teached me.*
Even tho I "somewhat" know about quantum mechanics at a basic level, and i know what weird effects it can produce, when you just explain refraction with quantum, the way the light takes every possible path, but the extremes cancels out, its like Wow, of course, OF COURSE!!! Now i understand it! Now everything makes sense!!
Dude, 10/10. You should be the first human to be granted immortality so you never stop warming our hearts with science.
Dude. DUDE. You are STILL blowing my mind after all these years.
🤯🤯 Glad I can deliver 👍
From the title I thought this would be a Relatively video, in answering why light bends in a gravitational field.
This taught me even more than I thought I needed to know.
I like how you're dealing every expansion in scale of Quantum particles... Please continue this series of "explaining everything quantum mechanically" please please please!
Those videos are all very, very different than all the explanations I've read/heard before
That certain mix of excitement (bcs AAAAHH SCIENCE HYPE) and fear (of the topic going way over my head) whenever a notif pops up is certainly something 😅
It's really worth so much to have a source of knowledge that challenges you while stil giving you a chance of grasping everything in the end.
Thanks for all your great work here!!!
4:40
Well it _might_ just be math. Seeing as there are multiple mathematical models of QM that all make exactly the same predictions and not all of them treat the wavefunction as a real thing, I don't think we can actually say with any real certainty whether a photon _actually_ takes multiple paths at once. All we can say with any certainty is that treating it mathematically like it does gives us accurate predictions, but that's not the only way to get accurate predictions.
I'm not opposed to the idea of it actually taking all paths at once -- if it really is a physical wave of some sort (as opposed to just being accurately modeled by a wavefunction), then I don't see how anything else would even be possible. But I do think it's important to be clear about what do and don't know for certain.
Fair point.
Exactly. I personally find the Copenhagen Interpretation absolutely ridiculous. The pilot wave theory and Bohmian Mechanics makes way more sense and is actually able to explain stuff like quantum tunneling, the Casimir effect, quantum entanglement etc..... without turning physics into a magic trick. The fact that modern science still won't let the Copenhagen Interpretation go for the obvious better model shows that some scientists are worse than religious people with their dogma. I am not saying this is true of Nick, his videos are great.
Thorough explanations, telling the little details, animations, explaining everything that's necessary in the same video, and some comedy. This is the best!
The impact these videos have is enormous. Even a physics teacher working for 70 years straight in 200 student classrooms couldn't reach as big as a crowd as you just did. Not only this, but your explanations are quick and don't leave out anything and gives you a hint as to what is next so that students can explore on their own, guided by your videos.
Now I'm just staring at my phone's camera lenses, these marvelous quantum mechanics devices!
LOL. Remember a few years ago when everything had "nano technology"?
Nick I can't find words to thank you.
Even if I can't support people on Patreon, you will always remain.
Even if it's only you I will ever support you.
All get 1 but you get 5 and for me it's money.
Love your work.
I'll share with some students.
Thank you!
Nick, you're a goddamn genius, I can't hold it down. Certainly many people have understood these concepts until now, and many have taught them to college students and graduates.
You were one day one of these many students that learned this. But you went beyond that, you learned, got the expertise on it necessary to dominate it, but the difference here is how very simply and intuitively you get to explain the whole concept of a lens for people that aren't necessarily grad students.
I don't know if you were taught the general concept in this simple, clear way, but I expect that you didn't. If so, you'd have to understand it extremely well to present this in a clearer way than the one you were teached with.
I think you exemplify what Feynman preached, by having great capabilities of explaining topics you prove yourself mastering those topics. Thank you very much, I'm deeply grateful for your teaching.
Thanks 😊
Wonderul video! A fine follow-up from the last one on mirrors. I literally clapped when clone asked if the photon really uses all paths and you slam dunked the quantum mechanics of lenses. Thank you very much!
Hooly crap, I had to replay this video 3 times to properly reabsorb the mindblow. I am blown away by your explanations whenever they involve quantum mechanics. You are completely changing my perception of the universe. I don't think I've ever seen such an elegant explanation of optics, and I've seen almost every video about optics.
Mind blown at 8 minutes. What a great explanation of how a lens works! Love your videos. The animation you did for the glass and straw was fantastic too. Thank you!
This really is a great "channel" Nick, The Science Asylum channel, you have impressive knowledge and mad animation skills, love it.
These videos are awesomeness!
Thank you for every single moment it takes to produce these ingenious videos.
You sir are what the world needs more of.
Now I actually understand how lenses work. Thanks!
You're welcome 🤓
Very true.
Man I have to say I just subscribed the other day and I love/ addicted to all your videos . Not only are you informative but you really explain in detail and I have a better understanding of all these topics ...you really made me a big fan !!!
I'm glad you found the channel 🙂
I LOVE THIS RUclips CHANNEL. Nick you've been doing a fantastic job of demystifying quantum with these videos about optics and electrodynamics! :D
As always, new video brings new revelation. This time it's about lenses.
Oh wow. I never thought of it that way. Keep up the good work, Nick.
This is one of the most consistently mind-blowing channels on RUclips.
Explanations like what you've made in this video bring the concept of "probability" down to something I can wrap my brain around. Can't claim to understand QM, but it isn't that impossibly mysterious thing it once was.
Another great Lucid lesson video.
Why aren't you doing lectures at the Royal Institute?
I'm not British?
@@ScienceAsylum non-sense! We had Sean Carroll and he wasn't very British the last time I checked. If I see him again, I'll ask if he can at least try to use Received Pronunciation. Let's get you over here, you're great!
Totally agreed as fan of Royal Institute lectures.
@ ‘CrouchingTigerHiddenAdam’
Non-sense is correct. We are all made of quantum particles which don’t obey classical equations appropriately.
@ ‘CrouchingTigerHiddenAdam’
Non-sense is correct. We are all made of quantum particles which don’t obey classical equations appropriately.
I'm just loving these videos where you use quantum mechanics to explain classic physics. ❤️
Thank you for taking the time to make this great video.
You are quickly becoming my fav science explainer channel on youtube. Love it bro!
7:49 friking epic
3D modellers pay attention, that engineering toolbox "refractive index" that Nick posted in the description is a goldmine for making materials
Which materials exactly? The only ones from that list that I could ever see myself using are alcohol, olive oil, and water. It has milk on there but that's opaque unless it's relevant for sub-surface scattering.
Awesome explanation!
It was very mindblowing when you came up with lenses and quantum mechanics.
Wish I’d learnt this way in high school!
That lens section was an eye opener.
Thanks for shining a lens on this tricky subject.
Awesome video as always
Way to explain very complex themes in very simple ways
Could you do a episiode on the interactions of electrons and protons?
I find it hard to grasp how 2 objects are atracted by emiting photons between each other
@ *Daniel Alexandre*
There are a lot of things that we understand how they work but not why. It’s still a mystery for many scientists.
Yea that atracting by photon is mistery for me too
Short Answer: They're not actually interacting by emitting photons between them. That's just a useful math trick to get us to an answer quickly on paper.
@@ScienceAsylum 🤔
So does that mean that the proton creates a bend on the electromagnetic field like mass does to space-time?
Thx for taking the time to answer my question btw
@@danielalexandre89 No, curved models don't work for E&M. Einstein tried for years with no success. As beautiful and simple as that would be, it's just not reality.
I love your explaination's. Constant regurgitation of terminology in presentation's phenomenally help's me.
Like everyone else, my mind is blown by how logically you presented this information to tie quantum and classical understanding of this phenomena together. Thank you so much. Just a brilliant moment of things clicking together in my brain.
This reminds of that Vsauce video about the brachistochrone and how light always obeys Snell's law. We have laws that as far as we can tell, the universe obeys, every single time. That's really awesome and scary at the same time.
Hey famous RUclipsrs, when 2 weeks later you do the same explanation your own way, at least remember this master piece.
Awesome job explaining how lenses work. I never thought of it that way. Keep up the good work!
The part that quantum mechanics could explain how all these laws work was such an amazing insight and well explained. Especially the lens part was incredibly satisfying. Thank you again for this inspirational video sir.
That was an absolutely "Genius" proof of concept! I'm showing this to my kids👍
We can't just go with it you said to question everything.
He's helping to answer questions so he means just go with his explanation until he's finished.
Good luck trying to find an explanation as to why quantum mechanical objects are probabilistic XD
Woooooaaaahhhhh...! Your channel is one of the best I found on RUclips. Your explanations are so understandable that they rival those of my high school physics teacher. That's the biggest compliment I can make, that guy was glorious as well.
Great Video once again! Where were you and this video 4 years when I was still teaching Physics. I could have related the quantum world to so many more "real" life examples for my students!
I'm personally still waiting on an explanation on quantum entanglement and "oh shit". or is that a big hole in a very major rule?
His quantum eraser video is probably the best on RUclips, enjoy!
There's no explanation. Neither for entanglement nor for wave function collapse. That's why there are so many interpretations of QM.
@@piranhaofserengheti4878 I always think of entangled particles of being part of the same object and the two points we observe are just it's protrusions from higher dimensions into ours. Think of a 3d circle passing through a 2d plane - two points of intersection which appear separate to the 2d dwellers as they can't see the rest of the object. As the communication 'time' between them is not in our dimension it's not subject to maximum speeds and therefore appears instant. Also it would account for changing one instantly altering the other in the opposite way.
Technically you made one misleading statement concerning refraction of a straw. Our brain (or some illusion, probably fooling our senses) has nothing to do with this pure physical phenomenon. And since your camera "sees" it all the same, this doesn't require the presence of a man to happen. It's just the light from the part of the straw inside the water happens to get to a different (shifted from expected continuation) place at retina, and likewise it gets to a different place at the matrix of the camera. Brain is not involved here.
Well, probably a brain is required to get amused by the fact that the straw is bent and exclaim: "What the heck?" :)
Beautifully and thoroughly explained as always. Love your videos!!
Excellent explanation! I had never even thought that lenses are shaped they way they are, all thanks to quantum mechanics! More videos like this please!
Υουr videos are just awesome
6:41
Déjà vu!
It really amazes me that only about two decades ago people were required to open up an intimidating textbook or take a course to learn anything about physics. If the encyclopedia was a big change, the internet should open new generations up to all sorts of innovations. I've learned a good bit from this channel over a small period of time and Its changed how I view things around me.. Keep it going man.
Every time, The Science Asylum finds some rabbit hole that expands upon what I had until now thought exhausted. Whoa.
Oh yeah we have an optic series now
Another edit is necessary.
@@bk-sl8ee what is wrong?
@@ekremdincel1505 series*
Our drone, is flown by our drone clone 😂😂
😂
okay wow the lens explanation i didn't see it coming but it made so much sense 🤯 i love your channel!!
Amazing animations Nick, greatly explained :)
Jut blown at quantum part
I will be back in a few minutes. I go to grocery store, in all possible paths!
try capturing the infinite phenomenons that intercept with you along the way in a painting
Mind ---> Blown !
This was sooo awesome, thank you for existing.
Love ur videos. Explaining in short time what has perplexed me all my life.
Only Nick manages to start a
The words "OMG, that's a lense" were exiting my mouth as you said the same thing!
Great video! You have a good way of explaining difficult to grasp concepts at an intuitive level. Can you do a video on non-linear optical effects like complex refractive indices, self focusing and multiphoton excitation, would be great to hear your input on it
really good and thought out examples!
New found respect for the humble lens. Great series of quantum-mirror-reflective-mechanics videos!!
That was the best explanation of how a lens works that I have seen I used to repair binoculars riflescopes and telescopes and I did it mostly intuitively . Watching your explanation gave me a flash of illumination
OMG! Friggin hell that lens thing was cool!! It just came out of the glass thickness and the quantum wave thing!! Man I love this channel - I have had several "Oh my, of course!" moments!!
Nice presentation. I was delighted that you depicted a photon as a wavelet rather than as a constant fixed height tube of em fields moving left to right across the screen, further the explanation of the lense effect was surprising and delightful. Thanks!
Wow! I need to watch this 20 times before I have a valid question. This video was awesome! Thank you for explaining things so simply and deeply at the same time.
You're very welcome! 🤓
It´s not enough that you learned this stuff and I surely hope your teachers were better than mine (took me ages to overcome the damage of one bad teacher in particular), you let us all take front row seats in what I can only describe as big bangs of knowledge in a very thought out minimalistic way. Brilliant! I think you should give courses in teaching, it´s a rare talent only bestowed on a selected few. Mostly not that well Paid, which is a scandal in itself. Keep up the great work. I´m a fan.
From quantum mechanics to a practical example explaining the shape of lenses.
Mind Blown
That is the coolest explanation of why a lens works that I have ever seen. Makes for a really good example of how quantum effects aren’t just ivory tower theoreticals.
OMG didn't expect that lens explanation which was really satisfying
I really think this channel is better than Veritasium... Better explanations and a lot funnier. Keep up the good work!
I started wearing glasses at eighteenths months old. I am now sixty-eight YEARS old. I finally understand the nitty-gritty of how my lenses work, and how the dirty lenses fuzz things up by complicating the probabilities of where the light went, or is, or may be. I think I’m probably a bit fuzzed out of shape now. But, I know why. I think. Wait, that’s must be why I couldn’t hit a baseball in little league. I didn’t know the probabilities of where the darn ball was!
Love your explanations. They are short, sweet, fun and to the point. You are my favorite quantum science guy.
Thanks Nick Once More An Excellent Episode. Thanks for sharing your knowledge with us 🧐😁👍
This is the best physics channel on RUclips by far!
This is probably one of the best explanations I've ever heard
you are amazing teacher☺. I understood refraction clearly. thank you for this video
First guy to ever make me take Griffiths up! Thanks Nick Lucid!