One of my favourite things about this channel, is that it doesn't dumb things down. It's very well explained! But it doesn't rely on mediocre metaphors to do so.
Exactly this! Back in highschool I always looked in higher level books to understand stuff, just saying "accept this and learn it by heart" didn't work for me. :)
i agree. i know there's kids and people who don't know, but sometimes it's likesometimes they start off everything as if we are in first grade, which is great, but sometimes it's like there's 5 minutes of actual discussion of the topic and the other 30 minutes is an introduction just to be able to talk about it. ive heard about the double slit experiment like 50 times just on UA-cam, more than i ever learned about it in school or before UA-cam physics videos were a thing...
That was a trip down the memory lane! During my master degree in phisics, my research group developed a self-referencing interferometric method to measure spatial and temporal coherence of light beams. It uses the interference between the field scattered by weakly interactive particles (a colloidal suspension of polystirene nanoparticles in water) and the uneffected field: each nanoparticle emits a weak spherical wave that produce a pattern of circular fringes, whose visibility contains the information about the coherence of the light beam. All the circular patterns combine to form a speckle field, but since the scattered intensity is small compared to the incident beam, you can ignore the second order interactions and it can be demonstrated that the 2D spatial autocorrelation of the speckle field provide a sort of "average" of all the single patterns, allowing you to extract the information on the coherence with a very good signal to noise ratio. As a bonus, since all the nanoparticles move randomly of brawnian motion, if you use the difference of two picture taken at different times you can remove all the source of static noise (defect on the cell, dust on the optics, etc) retaining all the statistical information of the changing interference patterns. This article explains all the theory and some applications Heterodyne Near Field Speckles: from laser light to X-rays, , Advances in Physics: X, 6:1, 1891001 DOI: 10.1080/23746149.2021.1891001
@@ronin6158 sorry for the late reply. Honestly, my (limited) understanding is that it doesn't really matter: "wave" and "particle" are just names that we gives to a particular subset of behaviors of any elentary particle. Under particular conditions photons undergo geometric scattering and carry momentum; under particular conditions electrons and protons produce diffraction and interference patterns. You can even merge or split photons, and it has been experimentally observed "quasi-particles" generated by almost any kind of vibration... So yeah, I think it would be hard even to give a clear and distinct definition of "particle" and "wave". Then you have some theoretical physicists saying that everything is made of vibrations of strings of extra dimensions coiled up together. What the fuck does it even means?!
The introduction of this video shows most of the channels I watch the most. And then there is yours, every time showing contents on a different new level, easier to grasp but somehow illuminating. I can’t thank you enough for producing this outstanding content!
I also watch these other channels but, apart from Physics Explained, I find them useful introductions to something I may wish to go and learn more about elsewhere. That's where this channel (and, again, Physics Explained) differ, they both offer the same intro but just go _that extra mile_ (sorry, I'm not very good with words) into the subject and at just the right level. There's just _more to it_ then the 8-minute wonder videos. Which is why I guess they're longer than 8 minutes, lol.
There are a handful of them that are absolutely useless. This dude here explains things much better. Leave the "science guy" to "nye" lol... Dorky presentations like action lab are half the problem with people's understanding.
@SVT tell me you've never studied physics at a college level without telling you've never studied physics at a college level; Also very american way of thinking, college is pretty much free all around the world, you base yourself on a shit premise I encourage people to go to college unlike this dumbass
@@harriehausenman8623 Agreed. As soon as possible, all scientists get free 'all the stuff (house, car, food, fun, no maid)' plus some kind of gamified equipment budget.
A photon NOT being light is the thing that makes the most sense here. In the same way that an electron isn't electricity. Btw. you are on your way to 100k subs. Congratulations!
Yes, I remember discussing this with you over a year ago when I still only had like a few thousand subscribers and thought it unlikely I would ever go over 10K. But in retrospect, making videos back then was just as much fun as it is now, so fortunately really nothing much has changed (apart from the time it takes to answer all those comments...).
I love how all these experiments on your channel are things I’ve read about but never seen a demo of. In complete honesty I woke up at 3 in the morning when you uploaded this to start watching it. No other channel on UA-cam captivates me like this one! Kudos!
The demo really helped me make sense of it, the hard part for me is understanding why Stimulated is temporally more coherent than Spontaneous. They both have the same wavelength and amplitude (after the filter) but since the stimulated emission is more orderly it's less quantized?
Your industry experience and the long time cooking your understanding is invaluable to understanding this beyond cliche textbook examples; thank you so much for doing these experiments for us and showing how to better think about these phenomena with cases beyond the flashy counterintuitive situations.
This is a great video! It reminds me of an article by William Beaty called Lasers: What is Coherent Light? His point is you can make any light source spatially coherent by putting it in front of a pinhole, but it also makes it dim. He then goes on to say "And finally I know why lasers are so wonderful: lasers are pinhole light sources which are ...actually bright!"
That raises the problematic truth that lasers are not different in kind from other light sources. Photons carry no memory of how they were generated. Laser radiation is not necessarily coherent, temporally or spatially. Conversely, coherent light does not only come from lasers. So there is literally nothing special about laser light. "Nothing special", as in, not a distinct species. The whole world, including physicists, thinks of laser light as different from all others, when it isn't.
@@RichardKinch One question I have, talking about temporal coherence. Is it fair to say that having high temporal coherence is equivalent to the source having a very narrow frequency bandwidth? Like if you put a narrowband source in front of a pinhole does it have both high temporal and spacial coherence? I don't know of many narroband sources other than lasers though. Maybe like a gas discharge tube?
@@Hunter271828 Narrowband, yes. And potentially a very stable center to the narrow. A narrowband filter on a broadband source is necessarily inefficient (i.e., dim) and the inverse method of a narrowband laser source.
I always wondered when people presented the double slit experiment due to Young by using lasers, often arguing that using lasers gives them the type of coherent light they need to see the fringes. But then how does Mr Young did it without lasers. Then once I saw a video by Veritasium where he researched how Mr Young did it back in the time. Basically, he made two small slits in a big black box to produce coherence. In the video this box is built btw.
I have struggled to wrap my brain around this optical stuff for years, and finally just "Not for me". This was super eye-opening, and it all started to click. This channel is rapidly becoming one of my favorites.
If I understand one of your main points correctly, it’s not light that behaves as a particle but the energy. Light itself is a wave but the energy involved (when transferred into or out of something else) behaves in a “particle-like” manner. That’s mind blowing and makes more sense than any other description of wave-particle duality I’ve ever heard. thank you.
EM Radiation are open loops... while Chemical matter is closed loops... when radiation is absorbed into chemical matter is momentarily acts like a particle (closed loop).
I teach my students that light is neither a particle nor a wave. Both are mathematically models which we can use to describe certain experimental observations. In my understanding, neither of the two (plus plain geometric optics as a third) models makes the claim to represent the true nature of light. We cannot in a better way (yet?) tell, what light is. We use the model which is easiest to use in order to explain an observation - I work with solar cells. The absorption of light in a semiconductor with a given band gap energy is easily explained with the photon model. The refraction of incident light through multiple layers with different diffractive indices, as well as the exponential Lambert-Beer absorption, standing wave phenomena etc are easily described by the wave model.
As I learned more about physics it slowly dawned on me that the weird thing about wave-partical duality isn't reality the duality but that light would ever behave as a particle at all since the wave model works so well. I think however that the particle model became so popular because it's incredibly easy to explain and it works really well as an explanation in most circumstances. Like the particle model works just fine for chemistry, biology and engineering and it's much easier to conceptualize than waves. Quantum mysticism shows us that people have a hard time understanding waves at all if they don't have any science education so it's not a shock that pop science generally relies on the particle model.
Fantastic explanation! Most other videos on the topic leave you with a sense of confusion as the presenter describes a magical process that defies common sense.
Probably because they never understood it to begin with. The Physics Explained video he referred to is what should be taught to cut off all the confusion on the subject.
Superb content as always ! This reminded me of a Feynman QED lecture where a guy in the class kept insisting that we simply "have to" use wave mechanics & Feynman was like, "NO Sir ! See, you already know too much". Calculating the probability of an event like a photomultiplier activating under specific conditions must be quite a different animal I suppose. At least that's my current nonsensical novice take. Anyway, I find ALL of this stuff very interesting. Such nifty equipment too. Really looking FWD to the rest of the series !
QED falls apart hard once you start asking questions about electrostatic interaction. With all due respect to Feynman, his logic works well only for cases where you already have emitted photons. For static fields it does not apply very well at all.
Timely as I work to explain spatial coherence to a client with a production optical problem. Thank-you for your insight and high quality experimental set-ups. You have given me more comprehensible arguments to particularly complex ideas. I hope I can return the favor one day in some small way.
Excellent video in all aspects - the clarity of the explanations, the pertinence of the illustrations, and the audacity to tackle such a difficult theme - many, many thanks!!!
I really appreciate your approach to answering your questions with experiment, and to be satisfied only when it makes sense intuitively, rather than being satisfied with a confusing answer from the consensus of popular ideas
Excellent as always. I love your explanations, and find the wave model of light to be far more intuitive than the corpuscular model for most practical purposes.
Thanks Les, I guess in lasers, there is no way around the wave character and it is actually quite difficult to find particle-like behavior. You can observe it in a detector when you attenuate a laser to very low intensity levels, however that has nothing to do with the light consisting of packets of energy. It's just the response of the detector to temporal constructive coherence.
Great video! I agree popular descriptions of QM get a lot wrong. I also think you're correct that Einstein was wrong in saying energy must be localized in a photon. I think a lot of the confusion re: wave particle duality comes from presenters (understandably) trying to skip teaching the basics of quantum mechanics before jumping into applications. It's very difficult to understand what physicists mean by terms like "superposition" and "uncertainty", and very easy to substitute in your own intuitive definitions. With that disclaimer, here's my shot at a high level explanation: I prefer to think of "wave" and "particle" as two "perspectives" you can view the same system from. If you make a wave-like measurement of the system (e.g. frequency), you'll see a wave. And if you make a particle-like measurement (e.g. position), you'll see a particle. Quantum mechanics says that both of these perspectives are valid, and furthermore: If you "project" the system into one perspective, its state from the other perspective becomes indeterminate. This means that if you make a wave-like measurement, it's impossible to determine the particle it originated from. Further, there's no one "fundamental" perspective: you can consider a particle as a wave packet consisting of a sum of many waves, and you can consider a wave as a sum of many particles. The math might be easier for one, but there's nothing special about the wave formulation. Everything I said above applies to *all* particles, not just photons. Most people are more comfortable thinking of electrons as particles, but their wave-like behavior is incredibly important to fields like solid-state physics. Another good comparison is the phonon, which is widely accepted to have particle-like behavior despite existing in a field. When you get even deeper, even the "more substantial" particles are quantized packets of their associated fields. So, philosophically, whatever you call a photon, you should call the electron, phonon, and proton the same.
Ever since I first heard about the so-called wave/particle duality many years ago I had the intuition that this had to be the case. That the electromagnetic field is “really” a wave and just the interactions are quantized into discrete packets of energy. Nice to see it explained so beautifully. Can’t wait for the next part!
There are so many great channels on UA-cam. Much better than any lecture I had in college. But yours is the only one that has me rewinding, watching again, thinking. Thank you!
Awesome video for my birthday! To explain why: This video actually beings up all those other videos I have watched that didn't make any sense, and actually went on to more interesting things with light than click bait science.
Please, please, please, keep diving into these basic concepts and misunderstandings. I recently had a revelation that for most fundamental concepts, there still wasn't made the perfect video that will provide you with an intuitive understanding of a phenomenon or at least an intuitive understanding of your own previous misunderstanding. What you are doing here is exactly that, and coming much closer than anything about quantum physics on YT I found so far (and I've been passively looking and watching for the past 4-5 years), narrowing down the question; "Why are we still confused about wave-particle duality?" to the assumption that photons, as packets of light are real. My brain is already going full throttle redefining the way I construct thought experiments about EM fields, atomic particles and waves. What I got from this video is that photon is a word, that attributes particle properties to a phenomenon that requires nothing else then wave superposition. Thank you for the gaussian explanation, this finally answered the question that puzzled my mind for a long time, how do you get infinite, continuous waves to form travelling, seemingly discrete packets. It's this ever shifting phase that creates this phenomenon. What I still don't quite grasp is the temporal aspect of it. Since we're talking about waves in a field, there must be an event of "shaking the substrate" that generates those waves and then probably some elastic damping going on until the source goes quiet. It would seem, that if you shake the substrate just for a little bit, you would get this wave packet anyway, since you were not generating waves before or after the event. The result should be the same. How does this tie in to the idea of waves that extend infinitely in space and time, yet when added up, they present you with this wave packet phenomenon? Is it purely a matter of point of view? If so, then infinitely extending waves are just a useful abstraction. The second thing that left me puzzling (as intended, I'm sure) is the absorption event. What does all this mean for quantized absorption? If we assume, that the EM wave passing by the atom starts shaking it and at a certain frequency, the atom can with certain probability decide to immediately absorb all of the shaking and use it to bump it's energy state. The question is - as time passes, the energy of the wave inevitable spreads in space. If it's spread in space, how can it be all of a sudden localized again? Unless it's another emergent trick of wave phenomena. The non-intuitive thing is how can energy of a "photon" be dependent on its frequency? Intuitively, as the wave spreads out, it still contains the same frequencies, but with lower amplitude, there simply must be an amplitude component to the energy of the final wave. The energy could then spread out "continuously" with aplitude, as expected, which would then lead to the conclusion that the absorption event can happen even at very low amplitudes, though with lower probability, since it's not the amplitude but the frequency of the local field that matters. So the claim that "photon's energy depends on it's frequency" would then be very, very, very, very misleading, since it holds true in its convoluted context, but doesn't generalize to intuitions about the wave phenomena, where the amplitude is the main "energy" component. However, now thinking about acoustic waves, same holds there as well. You have air particles moving back and forth, following a sine wave, if you have pure frequency. Given amplitude 1, the particles move distance 2 over the period of one wavelength. Since you have moved a mass a distance, you can compute work and then for low frequencies, one wave cycle takes a long time for the particle to travel, whereas in a high frequency it will travel the distance many times. So inevitably more energy must have been in the system, since more work was done in the same amount of time. I suspect this will be somehow analogous to the behavior of EM waves. Maybe I'm just babbling non-sense, but these are truly questions puzzling my mind I'm trying to figure out :D
Thank you for explaining temporal and spatial coherence. There was a different video I watched that mentioned them but didn’t explain either RC or SC very well. I’m glad UA-cam recommended your channel
I saw the title and thought I would watch it later... Until I realized it was from Huygens Optics and clicked immediately. I really really enjoyed your videos of the mini telescope!
🙏 how are you so damn good at making these videos for us! I hope everyone grasp the deeper meanings imbedded in your work, You really are a special one!
Thought provoking and educational as always, Jeroen! I'm looking forwards to where you're going with this. I implore you to consider into your thinking the typically neglected process of EM generation by means other than orbital electrons transitioning to lower energy states: EM radiation at microwave frequencies and below, basically RF. At those frequencies, "photon" generation can't be explained in terms of orbital electron transitions afaik, and so I think by understanding the factors common to both types of EM generation, we can better grasp what a "photon" is (and isn't).
I hope I have time to incorporate the equivalence of micro- and radiowaves to visible light in the second video. If not, I'll try to make a third video. Contrary to what some want to make you believe, there is not fundamental difference between the nature of the radiation. The difference in behavior is just due to wavelength and number of discrete radiative emitters.
@@HuygensOptics I certainly hope the topic makes it into one of your future videos! The point I was attempting to make isn't that there's a fundamental difference between the various categories of EM radiation or how it's generated, but rather that the common treatment given for photon production provides pretty limited insight into the actual physics that produces these waves/photons. For example, it seems to me that an electron falling to a lower energy state explains when/why a photon is released, but not how.
Really cool video! I never considered before that if a particle travels the speed of light, the only way to have different energy states is to have it change frequency, so "slowing" light would increase its frequency and that explains how optics redirect light! Neato! :D
Dude! Are you reading my mind?? Just as I’m trying to learn more about coherence the PREMIER optics teacher on UA-cam posts a video on it!! So hyped to watch this
This brings me back to my Eindhoven days at the NatLab, Philips' research- and technology center, where we developed the blue LED-laser (around 1989-1990, then still only functional in a liquid nitrogen immersion) and continued to develop the red LED-laser for improvements on the CD-player. I was occupied in handling an interferometer lab-setup, measuring the beam properties and reading the Zernike-polynomials from software that was resident on HP Pascal 9000 workstations. Experienced PhD's showed us, the humble technical-college assistants, the ropes of the trade. There was no internet, only books and whatever we learned from human contact during lessons and casual conversations. Those were the days...
Oh you slam dunked PBS Spacetime, I normally like that channel and host (and still do! They rock at explaining some wild concepts) but that just goes to show what an absolute goat market particle physics and especially information on particle physics for laymen has become. Also all the quantum woo I hate that. Thanks Huygens, you are an idol and wise master to me!
Now this is incredibly fascinating. I love when someone can clearly present a new way of understanding concept. This one sets my imagination on overdrive. Thanks!
Thank you very much, I'd never really understood the true meaning of coherence, in my courses we only talked about the conditions for which coherence was respected without even knowing what that really meant and now I know thanks to you!
I feel that you have come closer to explaining the "true nature" of light than just about any explanation I've run across. Is it a particle? Is it a wave? It is both, neither, and more. Light is as it is - not as the theory says. Dual nature? Sure. Extends from the macro (electricity / audio frequencies) to micro scales (gamma rays/wavelengths), why not? Reminds me of a discussion about one of Apple's latest products - that had tiny laser drilled holes for the speaker. And folks (some professional physicists with lots of letters) where stating that it can't / shouldn't work. The holes were less than 1/2 lamba of the wavelength blah blah blah! They had spent so much time with their nose against the blackboard using sine waves, trig, and calculus, as a model for what sound was they forgot what sound is - the compression & refraction of the medium through which it travels. The holes are nothing more than screen, cloth, etc. So long as they are large enough for the medium to move, sound will too. Once we truly understand (I'll borrow the term 'Grok' to mean 'true understanding') what light is, I believe we have many many more advances beyond where we are at now. Thank you for helping to advance the experimental, theoretical, and philosophical nature of this topic.
In the case of the tiny holes, they are so close together that they sound like a single source. Their sound emission is temporally coherent and at some distance, the sound will be spatially coherent as well.
Okidoki, in 7mins24sec the whole part-wave duality discussion summarized and decided. And as a bonus: it wasn't Einstein that mentioned Photons but Lewis. And.... "not for light" (double bonus thus). Never ever thought of it this way. THAT IS how a good, and above all basic, teaching is done. Klasse Jeroen, dit maakt mijn dag, verbreed mijn inzicht en zal ik nooit meer vergeten. Dank je, tnx !!
Wow, this helped me understand my studies on metamaterials. I know this is a part of the fundamental physics of light but presenting the concepts and experiment like this really motivates the audience to think further. Thank you!
Finally, someone has just proved what Ive been saying for years. The M&M interferometer is NOT able to measure or compare differences in light speed. It just showing a diffraction pattern that the equipment itself has generated, like Newtons Rings pattern also does this. The interferometer is not measuring the length between the two arms by comparing the phases. The apparent phases pattern is caused by misalignment of mirrors and the splitter. Here this researcher shows that he misaligned one of the mirrors on purpose. The it all want to crap when he was able to screw the hell out of the stage and nothing at all happened to the "interference pattern". Before you go claiming that the interferometer can measure differences in light speed, you need to demonstrate that the equipment can actually do that. But no one has ever done that. There is no setup to calibrate the equipment and then show it gives a correct response to a controlled condition of a known velocity.
@@schmetterling4477 The guy who made the video is a expert in the field of optics, give one example where his video was wrong. Anyway his video is not bullshit far from it, a great work of science. I would watch a video made by you, please make one as good as the above.
@@schmetterling4477 "“These days, every Tom, Dick and Harry thinks he knows what a photon is, but he is wrong,” and he directly said to physicists that “Every physicist thinks that he knows what a photon is, I spent my life to find out what a photon is and I still don’t know it,” and sometimes before his death in 1955, Einstein wrote “All the fifty years of conscious brooding have brought me no closer to the answer to the question: what are light quanta? ........... Of course, today every rascal thinks he knows the answer, but he is deluding himself” (4)." The opinion of Einstein. No course on quantum optics would answer Einstein's question to his satisfaction in my opinion. He was looking for an idea much deeper that you probably would say does not exist and I would say you are wrong.
Thanks for this. I'll be recommending this to people in the future. I'll looking forward to part 2. I suspect you're aware of this, but when you get into the math of how to quantize the electromagnetic field, the math is usually done in terms of coherent plane waves. Observables like energy and momentum are computed in terms of quantized excitations of plane wave modes. Photons mathematically have much more to do with counting these modes than corpuscles.
I chose to watch this over a SpaceX launch which was also waiting in my notifications this morning. I couldn't be happier with my decision. I am however pausing for just a bit to get a little more coffee in my system so I can be alert enough to retain the information :) Excellent content, really excellent! 100K subscriber button soon to be on its way I am sure.
It’s interesting to see the take of this subject with an optical perspective. I come from the land of microwaves and radio frequencies, where Doppler spectra and delay spread limit the coherence time and subsequently distance. I look forward to your demonstrations on spatial correlations, which we usually talk about in terms of angular spread. Knowing a bit about the gaussian beam as a valid solution to maxwells equations, I expect the results will be interesting and explain a lot about the difficulty in fast optics
I am not happy to admit that I lost quite a bit of enthusiasm for this channel when you released some videos using an EM-only interpretation of quantum mechanics, and even more so when Ben Krasnow was duped by its allure as well. It seems our community has never succeeded at finding a way of presenting the wave function that feels satisfying, hence the last century of people trying to find a way around it. I applaud you for openly revisiting your interpretation and hopefully continuing to shed "light" on difficult subjects via your masterful optics perspective. Still subscribed.
Well thanks anyway for the comment. I am convinced that quantization is only in the interaction of EM radiation with matter. I'm also convinced of the fact that any quantization of energy arises from particles actually being waves. The main problem I have with quantum mechanics is that most of it does not make sense to me. Because I don't want to be able to just describe, I want to be able to understand.
@@HuygensOptics Well, that is a tough one, indeed. I am probably not the person to convince you one way or the other. I agree it is uncomfortable having to work under a theory for which we lack the sophistication or knowledge to interpret fundamentally. Hopefully one day we will. I can say that relinquishing a little bit of that sense of "knowing" is a gateway to utilizing quite a bit of predictable and repeatable outcomes which simply cannot follow from EM. If you ever feel a little dangerous, I think you would be very quick to pick up the subject. That said, I admire your colossal efforts to illuminate opaque subjects, and your insights are excellent. I also hope that I never have to go toe-to-toe with you in optics. Truly wishing you well, and interested to see what you come up with in part 2.
With this and Ben's channel it feels more like taking a journey together and trying out explanatory frameworks and see where they break. A long path with lots of windings and even some U-turns. With most other YT channels, it feels like being abruptly placed in the center of the destination and then hearing the explanation how we got there.
@@harriehausenman8623 I really appreciate this perspective. I have followed each of them since their early days on the platform, and I treasure the opportunity to watch a disciplined outsider bring fresh insights into seemingly impenetrable topics. I want to make it very clear that I have the utmost respect for this pursuit, and I think it is far easier to criticize than it is to create. The last thing I would want to do is discourage someone from an honest foray into rigorous discovery and teaching. However, because of this, it is at very best misleading not to distinguish what one considers to be one's own speculation from that of which one is "convinced." Especially in learning quantum mechanics, there is such a temptation to find the "Eureka!" moment, students seem to be biased toward simpler interpretations over more applicable ones. If I watched these few videos as a student, I would probably have struggled to reject their premise later, because it feels so much like the missing piece of intuition. Most of my knowledge outside of Physics is informal, but it represents the great majority of what I have learned. Rejecting explanations, trying crazy ideas, seeing where they break. I respect anyone willing to take on that journey. Trying out frameworks without a strong theoretical background requires a healthy dose of doubt at every stage, as well as a hunger for finding something that changes one's own mind. Being able to model that for thousands of others is a precious thing, and I just wanted to give a little nudge to someone I respect. That said, I think the path Huygens Optics is on has been very fascinating. Maybe he's going to discover where the framework breaks, own up to it, and have gained 10x the understanding of someone who just believed what they were told. That would be a beautiful and rare lesson for thousands of people, showing that it is okay (and truly an advantage) to doubt everything, including doubt. My only hope is that he can share a little more of that during the journey for the people just getting started. Having a population who can access that perspective seems important now more than ever.
Amazing video. I'm not up to snuff on my laser physics, but the results shown at the end would mean that for stimulated emission we have a much more precisely defined band gap (or whatever is between the excited state and the base state) in the material. Whereas with spontaneous emission we have a much wider range of energy gaps across which the electrons relax. Using the equation shown at 19:15 I get a DeltaNu of 90meV. That's not a lot, but much more than I would have expected. 635nm means a 1.95eV wide "default" band gap, so DeltaNu is 1/20th of that. I wonder where the difference comes from. I know that an exciton (electron/hole pair) in a semiconductor creates its own potential well, but that would only explain deviations in one direction, a lower energy gap, so it can't be the complete answer.
I guess there is a lot of things that can contribute to spectral broadening in a doped lattice, like statistical variations in the surrounding of the emitter. Also, a variety of thermal effects should be taken into consideration, which cause exited state life time variations. And- contrary to my expectations- the transition to lasing was actually way more gradual than I expected. Anyway, this is what I measured.
@@HuygensOptics I don't see an obvious connection from the life time of the excited state to the energy of it. The statistical variations certainly contribute to the spread. I don't know enough to quantify their influence. EDIT: So I did some research and feel kinda stupid for not thinking about it earlier... A Laser diode is just a regular pn-diode, in a semiconductor with a direct band gap, with a current sent across the depletion region in flow direction. Until we reach the threshold voltage, aka before we begin lasing, we have only rare charges traveling across the depletion region. Those charges can either recombine across the bandgap, but they can also tunnel a bit, trading the tunneled distance for a difference in energy difference (because of the internal electric field of the depletion region, distance equals energy for charged particles). The probability of the resulting energy gap is not trivial, but I can easily imagine that this results in a gaussian distribution. 90meV are also easily explained with this. Depending on the doping concentration an electric field with 1V/50nm is easily possible (by intuition, didn't do the math), meaning 5nm would have to be tunneled which is realistic.
And the Neutrino Muon G2 Result ( Proven by hydrogen outputs of Neutrino collisions, TempA+TempB+1ºC) Every "Particle" is just a whole in space ;-) Skin Theory - The Higgs velocity mechanism General Relativity: TDR = (Temp/5)^2 seconds (+1c^3 == +1ºC) Lorentz Gamma: TDR = V/c Vc: TDR = (V-c)/c == (Temp/5)^2 seconds ... So for the Muon G2 result we have ... +3x10^8m/s == +1c^3 == +1ºC Which implies Zero Degree Celsius space has a stationary in situ energy potential = At least the Speed of light (i.e. A distance to the the zero line of the BB space). 1c from our 3d space potential. 1c from the Velocity addition over c of the collision (**Into the BB weight space??). 1c from the depth into the BB weight space temperature aperture. (Causes a dowel like flow of space towards the Big Bang aperture binding the two space connection open) This implies the exhibited temperature should be half input temperature because of BB space redshift (**a c^3 additive superimposed distance??). M.B.Eringa, DrDon 1998~Jul 2022 PS: There is an implication that the interface angle between our visible space and the BB space is always 90º regardless of Visible space vector direction!. References: DrDon; Garret; Stephen Hawking; PPS: Garret and myself have long been discussing the top of the C^3 weight space scale. Based on the Higgs velocity mechanism, I am thinking that the scale above the zero line on the atomic scale (i.e. our 3d space side) should be in 1c increments until the zero line and then swap to 1c,1c^2 and 1c^3 increments below the zero line. (i.e. +1c==+1ºC for speeds up to the speed of light) The tricky thing is, the zero line is the top of the c scale, and our 3d spaces' zero line is its' weight temperature back from that zero line, so the scale should actually look like the below for a plutonium "proton" ... + 0c + 1c ... + 20,000c + 0c^3 + 1c^3 .... + 20,000c^3 The magnetic aperture starts at the BB space but the spacial flow "dowel" needs to go the same c distance back into our space, although it likely will collapse into a 3 dimensional sphere afterwards, the magnitude still needs to be represented on the diagram using the c scale. So now I can say this categorically ... Velocity based time dilation calculation So we have V/c gives us a result in degrees Celsius. We live at electron weight, so weight when moving matter would be 5+(V/c) So traveling at the speed of light you have a Time Dilation Factor of (6/5)^2 or 1.44 Seconds Observed for the matters' one second. M.B.Eringa 1981 - 2023
So much conflicting information on single photon/quanta self interference. You seem to get a different answer on every paper or experiment you read. There seems to be a huge amount of confusion on this even among the professionals and experiments. One thing I do not see talking about is that in slit experiments is the knife edge diffraction. In the related subjects there has also been a lot of misinformation on the so called on the quantum eraser and other matters. Part 2 will be interesting. Thanks for making these.
A good visualization of Schrodinger’s time dependent wave equation is the 4 minute video in the “Above Threshold” channel called “A quantum mechanics simulation with an explanation”. Although it’s a calculation of the dual slit experiment for an electron, it is very similar to the lab measurement results obtained by Huygens optics in his dual slit experiment. It even includes standing waves inside the dual slits themselves.
It is really strange that sometimes in science when they try to simplify things, as the result we get confusion and even more misunderstanding as with photons. Well remember when I had some problems with understanding of information theory in university due to all it's "simplifications" represented by short definitions and lots of formulas. It wasn't until I read the original articles by Claude Shannon that I understood "yes, that makes sense and is pretty simple".
I am a big fan of this channel, and watch most of the videos several times (probably because I am not intelligent enough to understand the first time....!) One of the thing with this explanation that haunts me is that an experiment with Bucky balls have shown that they too show interference patterns. How does that marry up with this explanation? Thanks again for the significant effort you put in to create premium content.
Big Thanks to you Jeroen for this awesome good video. I appreciate all your videos but this one really stands out and try to explain some long hair content not too simplified. When looking at the wave packet it just remain me about the mathematic for Soliton equation and the behavior, that Soliton can travel through another wave or Soliton without getting distorted when it come out again, same as your two coherent light beams crossing each other. Also thanks for the music video I am a big fan.
One of the most interesting things you teased here was the question of how a particle can absorb a fixed quantum of energy from a wavefront that has spread out over a large area. You said you'd come back to that point but never did! I am deeply intrigued by that thought, so I am really hoping you come back to address that point in a later video :)
There are no particles. There are only people who didn't pay attention in high school where we have been teaching for approx. 50 years that "quanta" are small amounts of energy. The differentiation between "has" a quantum of energy "and is a quantum of energy" is absolutely crucial here. If you don't understand the difference then you will never get the correct ontology for quantum mechanics.
To be more specific: if there are no particles then... what is an 'electron'? What is a 'state' and what is a 'state transition' ? And then ultimately what is the measurement problem? Assuming this is too much to answer in a comment section, is there a video you can link that explains all these things so I can get your overall gist?
@@iestynne We have been teaching the photoelectric effect for half a century as far as I know. The photoelectric effect is an interaction between the electromagnetic field and a metal in which a photon (a quantum of electromagnetic energy) is being exchanged by the field and the solid. When taught properly no mention should be made of photons as particles because the photoelectric effect experiment is completely macroscopic and does not detect "particles" in any way, shape or form.
@@iestynne An electron is also a quantum of energy. The only complication there is that special relativity allows for two different dispersion relations, one for massive quanta and one for massless ones. This we can not teach at the high school level, not even conceptually. Once you learn quantum field theory at the graduate course level you will see why "massive" quantum fields are not a good idea. The standard model therefor uses all massless "naked" fields and mass becomes effective mass through the Higgs mechanism and couplings to other fields. Mathematically this is seriously complicated and I am not the right person to ask about the details. For that you need a theorist. I am an experimentalist. What I can tell you is that nobody has ever performed an experiment in which we have detected particles. We are only ever detecting quanta of energy. What we do see in experiments with high energy "particles" are not particles. We see particle tracks. How they follow from wave mechanics (which is not even the full theory) has been explained in 1929 by Mott, so the actual phenomenology has been covered by theory almost since day one. Very few people know about that paper, though, which leads to an endless comedy of errors about the existence of "particles".
Just found your channel and subscribed. Brilliant work. Generating new questions... @ 18:41 clearly these patterns are the frequency content (spectrum) of a single square wave pulse. Is light (a photon) a pulse, and continuous light overlapping pulses cancelling out all wavelengths other than the fundamental? Looking forward to part 2.
Thank you for bearing the torch. There is a paper on arXiv that touches on these concepts called "Do photon-number-resolving detectors provide valid evidence for the discrete nature of light?"
Thank, interesting paper. It seems that many "single photon" detectors have insufficient SNR to do accurate measurement because the noise floor can alter statistics significantly. Do you know the source of the noise? Is that thermal?
@@HuygensOptics The paper concerns "multi photon" detectors composed in a multiplexed scheme where multiple "single photon" detectors are joined through a beamsplitter network. When two detections happen "close enough" in time the result is deemed a detection of a "two photon state". At least one of the sources of the insufficient SNR is the underwhelmingly prosaic mismatch of the temporal coherence of the optical source and the so-called coincidence window for the PNR detectors (widespread in many experimental works in the literature), where the coincidence window is longer than the coherence time, therefore inflating the resultant number of "multi photon" events. You'd be surprised to see how many research groups pay no mind to simple coherence theory. "Single photon" detector-wise the greatest impediment to a good SNR is the reset (or "dead") time not allowing high count rates. (As shown in the SNR equation) I imagine you've encountered the cognitive resistance to even entertaining the idea of abandoning the photon (or quantized field). I can assure you that just like the phlogiston, it will die hard among the scientific community, and perhaps take much longer. The only thing harder than discovering a certain truth about the universe is convincing other humans who are anchored and invested in the old paradigm.
At 18m12s, that picture is true if the tones are harmonically related and start at zero phase. If not, it'll look more like white noise in the time domain, with some reduced PAPR (peak to average power ratio). In RF/microwave synthesis and communication systems, there are algorithms to adjust the individual phases of multi-tone signals in order to minimize pulse trains with high peak voltages, which would otherwise drive amplifiers into highly non-linear operation. Same at 18m39s, the phase distribution of the infinite carriers has to line up just so. A Fourier transform isn't just the power spectral density, the phase information is important too. That frequency domain plot could just as easily depict a single tone with phase&litude noise, which in the time domain would look like a sinewave with a bit of variation on the phase and amplitude.
Sure, phase information is important especially in Inverse Fourier transforms. In the images, all frequencies are assumed to have the same zeropoint for every frequency. Which of course isn't the case in spectrally broad light. Unless of course you compare the phase of every frequency with itself, as is done in the Michelson interferometer.
Love your content, your insight and the quality of the content you provide. Your view on light being a wave and NOT a particle is a rare thing these days. Keep up the great work.
We never told you that light is made of particles. We told you in high school that the electromagnetic field exchanges energy with external systems in form of discrete amounts that are called photons. That's a very, very different scenario than "particles".
So, it is just a wave as i was thought. But i already changed view on topic, photon can just be a particle with varying parameter so it is creating interference by sum of parameters of many particles absorbed at one time. You can simulate waves by field, but you can simulate waves by shortest path algorithm.
Thanks for the link to the Physics Explained channel Wave Packet video. Now I am wondering if you could make a video demonstrating the production of single photons. Simply reducing the intensity until there is only ony photon left never seemed like a very elegant solution to me. I love to ee you actually demonstrating things with real hardware !
I have for some months been trying to imagine EM phenomena as field perturbations and visualize them in my head. so far all I can handle are radio frequencies. This will help me get over the Terahertz gap ;)
One of my favourite things about this channel, is that it doesn't dumb things down. It's very well explained! But it doesn't rely on mediocre metaphors to do so.
The tragedy our our time is our belief that knowledge is the same as understanding a metaphor.
Very well said.
Exactly this! Back in highschool I always looked in higher level books to understand stuff, just saying "accept this and learn it by heart" didn't work for me. :)
i agree. i know there's kids and people who don't know, but sometimes it's likesometimes they start off everything as if we are in first grade, which is great, but sometimes it's like there's 5 minutes of actual discussion of the topic and the other 30 minutes is an introduction just to be able to talk about it. ive heard about the double slit experiment like 50 times just on UA-cam, more than i ever learned about it in school or before UA-cam physics videos were a thing...
@@amarissimus29 wow. that was deep.
That was a trip down the memory lane!
During my master degree in phisics, my research group developed a self-referencing interferometric method to measure spatial and temporal coherence of light beams. It uses the interference between the field scattered by weakly interactive particles (a colloidal suspension of polystirene nanoparticles in water) and the uneffected field: each nanoparticle emits a weak spherical wave that produce a pattern of circular fringes, whose visibility contains the information about the coherence of the light beam. All the circular patterns combine to form a speckle field, but since the scattered intensity is small compared to the incident beam, you can ignore the second order interactions and it can be demonstrated that the 2D spatial autocorrelation of the speckle field provide a sort of "average" of all the single patterns, allowing you to extract the information on the coherence with a very good signal to noise ratio. As a bonus, since all the nanoparticles move randomly of brawnian motion, if you use the difference of two picture taken at different times you can remove all the source of static noise (defect on the cell, dust on the optics, etc) retaining all the statistical information of the changing interference patterns.
This article explains all the theory and some applications
Heterodyne Near Field Speckles: from laser light to X-rays, , Advances in Physics: X, 6:1, 1891001
DOI: 10.1080/23746149.2021.1891001
I did not understand much but I’m still excited for it!! ahahaha
Pretty impressive stuff. What's your opinion on light being purely a wave?
Are the strings of numbers a computational thing. Goodness , I been
at this too long for sure
@@ronin6158 sorry for the late reply.
Honestly, my (limited) understanding is that it doesn't really matter: "wave" and "particle" are just names that we gives to a particular subset of behaviors of any elentary particle. Under particular conditions photons undergo geometric scattering and carry momentum; under particular conditions electrons and protons produce diffraction and interference patterns. You can even merge or split photons, and it has been experimentally observed "quasi-particles" generated by almost any kind of vibration...
So yeah, I think it would be hard even to give a clear and distinct definition of "particle" and "wave".
Then you have some theoretical physicists saying that everything is made of vibrations of strings of extra dimensions coiled up together. What the fuck does it even means?!
The introduction of this video shows most of the channels I watch the most. And then there is yours, every time showing contents on a different new level, easier to grasp but somehow illuminating. I can’t thank you enough for producing this outstanding content!
I also watch these other channels but, apart from Physics Explained, I find them useful introductions to something I may wish to go and learn more about elsewhere. That's where this channel (and, again, Physics Explained) differ, they both offer the same intro but just go _that extra mile_ (sorry, I'm not very good with words) into the subject and at just the right level. There's just _more to it_ then the 8-minute wonder videos. Which is why I guess they're longer than 8 minutes, lol.
maybe it comes with age...
Well said: illuminating
There are a handful of them that are absolutely useless.
This dude here explains things much better.
Leave the "science guy" to "nye" lol... Dorky presentations like action lab are half the problem with people's understanding.
man, i remember not even caring about any of this sort of stuff that all these other channels would get into until after i discovered this one
i took an optics course in college because of you! thanks for the videos!
hell yeah brother!
Same, lol. Shared the link around the class, too.
@SVT tell me you've never studied physics at a college level without telling you've never studied physics at a college level;
Also very american way of thinking, college is pretty much free all around the world, you base yourself on a shit premise
I encourage people to go to college unlike this dumbass
Excellent video! You managed to weave together a huge amount of content in under 30 minutes, without skimping on detail. I learnt a lot. Thank you
Thank you for this compliment. It coming from you really means a lot to me!
I'm so glad I found this channel. This is the real sience, with experiments, reason, and doubt!
Agreed! Contrary to popular belief, real free-thinking scientists are rare.
@@sean_vikoren To be fair, that is mostly because scientists also still have to eat 😆
@@harriehausenman8623 Agreed.
As soon as possible, all scientists get free 'all the stuff (house, car, food, fun, no maid)' plus some kind of gamified equipment budget.
@@sean_vikoren 😁
A photon NOT being light is the thing that makes the most sense here. In the same way that an electron isn't electricity.
Btw. you are on your way to 100k subs. Congratulations!
Yes, I remember discussing this with you over a year ago when I still only had like a few thousand subscribers and thought it unlikely I would ever go over 10K. But in retrospect, making videos back then was just as much fun as it is now, so fortunately really nothing much has changed (apart from the time it takes to answer all those comments...).
I love how all these experiments on your channel are things I’ve read about but never seen a demo of. In complete honesty I woke up at 3 in the morning when you uploaded this to start watching it. No other channel on UA-cam captivates me like this one! Kudos!
My notifications wake you up?? Wow, now that is dedication!
So true. Same here. (except for the waking up part ☺)
The demo really helped me make sense of it, the hard part for me is understanding why Stimulated is temporally more coherent than Spontaneous.
They both have the same wavelength and amplitude (after the filter) but since the stimulated emission is more orderly it's less quantized?
Can't wait for part 2. I've been scratching my head for years about these issues.
Your industry experience and the long time cooking your understanding is invaluable to understanding this beyond cliche textbook examples; thank you so much for doing these experiments for us and showing how to better think about these phenomena with cases beyond the flashy counterintuitive situations.
This is a great video! It reminds me of an article by William Beaty called Lasers: What is Coherent Light? His point is you can make any light source spatially coherent by putting it in front of a pinhole, but it also makes it dim. He then goes on to say "And finally I know why lasers are so wonderful: lasers are pinhole light sources which are ...actually bright!"
That raises the problematic truth that lasers are not different in kind from other light sources. Photons carry no memory of how they were generated. Laser radiation is not necessarily coherent, temporally or spatially. Conversely, coherent light does not only come from lasers. So there is literally nothing special about laser light. "Nothing special", as in, not a distinct species. The whole world, including physicists, thinks of laser light as different from all others, when it isn't.
@@RichardKinch One question I have, talking about temporal coherence. Is it fair to say that having high temporal coherence is equivalent to the source having a very narrow frequency bandwidth? Like if you put a narrowband source in front of a pinhole does it have both high temporal and spacial coherence? I don't know of many narroband sources other than lasers though. Maybe like a gas discharge tube?
@@Hunter271828 Narrowband, yes. And potentially a very stable center to the narrow. A narrowband filter on a broadband source is necessarily inefficient (i.e., dim) and the inverse method of a narrowband laser source.
I always wondered when people presented the double slit experiment due to Young by using lasers, often arguing that using lasers gives them the type of coherent light they need to see the fringes. But then how does Mr Young did it without lasers. Then once I saw a video by Veritasium where he researched how Mr Young did it back in the time. Basically, he made two small slits in a big black box to produce coherence. In the video this box is built btw.
I have struggled to wrap my brain around this optical stuff for years, and finally just "Not for me". This was super eye-opening, and it all started to click. This channel is rapidly becoming one of my favorites.
If I understand one of your main points correctly, it’s not light that behaves as a particle but the energy. Light itself is a wave but the energy involved (when transferred into or out of something else) behaves in a “particle-like” manner. That’s mind blowing and makes more sense than any other description of wave-particle duality I’ve ever heard. thank you.
EM Radiation are open loops... while Chemical matter is closed loops... when radiation is absorbed into chemical matter is momentarily acts like a particle (closed loop).
The more I watch your channel, the more I like optics. Thank you for that.
Very coherent presentation. The work you put in is amazing.
Temporal Coherence is really not the easy topic to understand it correctly. Thank you for such a great lesson!
I teach my students that light is neither a particle nor a wave. Both are mathematically models which we can use to describe certain experimental observations. In my understanding, neither of the two (plus plain geometric optics as a third) models makes the claim to represent the true nature of light. We cannot in a better way (yet?) tell, what light is. We use the model which is easiest to use in order to explain an observation - I work with solar cells. The absorption of light in a semiconductor with a given band gap energy is easily explained with the photon model. The refraction of incident light through multiple layers with different diffractive indices, as well as the exponential Lambert-Beer absorption, standing wave phenomena etc are easily described by the wave model.
As I learned more about physics it slowly dawned on me that the weird thing about wave-partical duality isn't reality the duality but that light would ever behave as a particle at all since the wave model works so well. I think however that the particle model became so popular because it's incredibly easy to explain and it works really well as an explanation in most circumstances. Like the particle model works just fine for chemistry, biology and engineering and it's much easier to conceptualize than waves. Quantum mysticism shows us that people have a hard time understanding waves at all if they don't have any science education so it's not a shock that pop science generally relies on the particle model.
Fantastic explanation! Most other videos on the topic leave you with a sense of confusion as the presenter describes a magical process that defies common sense.
Probably because they never understood it to begin with. The Physics Explained video he referred to is what should be taught to cut off all the confusion on the subject.
Superb content as always ! This reminded me of a Feynman QED lecture where a guy in the class kept insisting that we simply "have to" use wave mechanics & Feynman was like, "NO Sir ! See, you already know too much". Calculating the probability of an event like a photomultiplier activating under specific conditions must be quite a different animal I suppose. At least that's my current nonsensical novice take. Anyway, I find ALL of this stuff very interesting. Such nifty equipment too. Really looking FWD to the rest of the series !
QED falls apart hard once you start asking questions about electrostatic interaction. With all due respect to Feynman, his logic works well only for cases where you already have emitted photons. For static fields it does not apply very well at all.
Timely as I work to explain spatial coherence to a client with a production optical problem. Thank-you for your insight and high quality experimental set-ups. You have given me more comprehensible arguments to particularly complex ideas. I hope I can return the favor one day in some small way.
Excellent video in all aspects - the clarity of the explanations, the pertinence of the illustrations, and the audacity to tackle such a difficult theme - many, many thanks!!!
can't wait for part 2. The more I study about optics the more confused I become, and calling photons particles has never helped.
I really appreciate your approach to answering your questions with experiment, and to be satisfied only when it makes sense intuitively, rather than being satisfied with a confusing answer from the consensus of popular ideas
The most intuitive explanation of the most fundamental principles that are elusive everywhere else
Also completely wrong. ;-)
Meter:9 air:3125 light:64
Excellent as always. I love your explanations, and find the wave model of light to be far more intuitive than the corpuscular model for most practical purposes.
Thanks Les, I guess in lasers, there is no way around the wave character and it is actually quite difficult to find particle-like behavior. You can observe it in a detector when you attenuate a laser to very low intensity levels, however that has nothing to do with the light consisting of packets of energy. It's just the response of the detector to temporal constructive coherence.
Both of your videos are fascinating. The graphs at 18:40 and Les' most recent videos give me some idea as to what part 2 might be about.
this is really eye opening stuff. It really crystallized the energy/wavelength/uncertainty concept for me
So intrigued, can't wait for the second part!
Great video! I agree popular descriptions of QM get a lot wrong. I also think you're correct that Einstein was wrong in saying energy must be localized in a photon.
I think a lot of the confusion re: wave particle duality comes from presenters (understandably) trying to skip teaching the basics of quantum mechanics before jumping into applications.
It's very difficult to understand what physicists mean by terms like "superposition" and "uncertainty", and very easy to substitute in your own intuitive definitions. With that disclaimer, here's my shot at a high level explanation:
I prefer to think of "wave" and "particle" as two "perspectives" you can view the same system from. If you make a wave-like measurement of the system (e.g. frequency), you'll see a wave. And if you make a particle-like measurement (e.g. position), you'll see a particle. Quantum mechanics says that both of these perspectives are valid, and furthermore: If you "project" the system into one perspective, its state from the other perspective becomes indeterminate. This means that if you make a wave-like measurement, it's impossible to determine the particle it originated from. Further, there's no one "fundamental" perspective: you can consider a particle as a wave packet consisting of a sum of many waves, and you can consider a wave as a sum of many particles. The math might be easier for one, but there's nothing special about the wave formulation.
Everything I said above applies to *all* particles, not just photons. Most people are more comfortable thinking of electrons as particles, but their wave-like behavior is incredibly important to fields like solid-state physics. Another good comparison is the phonon, which is widely accepted to have particle-like behavior despite existing in a field. When you get even deeper, even the "more substantial" particles are quantized packets of their associated fields. So, philosophically, whatever you call a photon, you should call the electron, phonon, and proton the same.
Ever since I first heard about the so-called wave/particle duality many years ago I had the intuition that this had to be the case. That the electromagnetic field is “really” a wave and just the interactions are quantized into discrete packets of energy. Nice to see it explained so beautifully. Can’t wait for the next part!
Great work! Finally a practical demonstration that shows how light can appear as a continuous wave or discrete packets or photons.
I have never seen such beautiful and well explaining coherence experiments during all my time at the university. Hats off!
Your videos always show me how much more there is to learn about light.
There are so many great channels on UA-cam. Much better than any lecture I had in college. But yours is the only one that has me rewinding, watching again, thinking. Thank you!
Awesome video for my birthday! To explain why: This video actually beings up all those other videos I have watched that didn't make any sense, and actually went on to more interesting things with light than click bait science.
Happy birthday! I guess this is my present for you then ;-)
@@HuygensOptics Looking forward to part 2! :D
Yeah! Happy Birthday! 🎂🥳🎆
That dull yet snappy sound was my mind blown. To bits.
(edit) Field Physics is the key to understanding discrete phenomenon.
Please, please, please, keep diving into these basic concepts and misunderstandings. I recently had a revelation that for most fundamental concepts, there still wasn't made the perfect video that will provide you with an intuitive understanding of a phenomenon or at least an intuitive understanding of your own previous misunderstanding. What you are doing here is exactly that, and coming much closer than anything about quantum physics on YT I found so far (and I've been passively looking and watching for the past 4-5 years), narrowing down the question; "Why are we still confused about wave-particle duality?" to the assumption that photons, as packets of light are real.
My brain is already going full throttle redefining the way I construct thought experiments about EM fields, atomic particles and waves. What I got from this video is that photon is a word, that attributes particle properties to a phenomenon that requires nothing else then wave superposition. Thank you for the gaussian explanation, this finally answered the question that puzzled my mind for a long time, how do you get infinite, continuous waves to form travelling, seemingly discrete packets. It's this ever shifting phase that creates this phenomenon. What I still don't quite grasp is the temporal aspect of it. Since we're talking about waves in a field, there must be an event of "shaking the substrate" that generates those waves and then probably some elastic damping going on until the source goes quiet. It would seem, that if you shake the substrate just for a little bit, you would get this wave packet anyway, since you were not generating waves before or after the event. The result should be the same. How does this tie in to the idea of waves that extend infinitely in space and time, yet when added up, they present you with this wave packet phenomenon?
Is it purely a matter of point of view? If so, then infinitely extending waves are just a useful abstraction. The second thing that left me puzzling (as intended, I'm sure) is the absorption event. What does all this mean for quantized absorption? If we assume, that the EM wave passing by the atom starts shaking it and at a certain frequency, the atom can with certain probability decide to immediately absorb all of the shaking and use it to bump it's energy state. The question is - as time passes, the energy of the wave inevitable spreads in space. If it's spread in space, how can it be all of a sudden localized again? Unless it's another emergent trick of wave phenomena. The non-intuitive thing is how can energy of a "photon" be dependent on its frequency? Intuitively, as the wave spreads out, it still contains the same frequencies, but with lower amplitude, there simply must be an amplitude component to the energy of the final wave. The energy could then spread out "continuously" with aplitude, as expected, which would then lead to the conclusion that the absorption event can happen even at very low amplitudes, though with lower probability, since it's not the amplitude but the frequency of the local field that matters. So the claim that "photon's energy depends on it's frequency" would then be very, very, very, very misleading, since it holds true in its convoluted context, but doesn't generalize to intuitions about the wave phenomena, where the amplitude is the main "energy" component.
However, now thinking about acoustic waves, same holds there as well. You have air particles moving back and forth, following a sine wave, if you have pure frequency. Given amplitude 1, the particles move distance 2 over the period of one wavelength. Since you have moved a mass a distance, you can compute work and then for low frequencies, one wave cycle takes a long time for the particle to travel, whereas in a high frequency it will travel the distance many times. So inevitably more energy must have been in the system, since more work was done in the same amount of time. I suspect this will be somehow analogous to the behavior of EM waves.
Maybe I'm just babbling non-sense, but these are truly questions puzzling my mind I'm trying to figure out :D
It seems that according to the Compton effect, photons have directions as well. This place needs careful consideration
Your videos are such a joy!
Why can´t every human be like that, and share there knowledge?!
Specially if it is that fundamental. 🙏
I am a huge fan of these Huygensoptics videos. I use these with my students at UCSD. Thanks for the great work!
this is becoming one of my favorite channels on youtube. I think these explorations will be extremely important in the future
Thank you for explaining temporal and spatial coherence. There was a different video I watched that mentioned them but didn’t explain either RC or SC very well. I’m glad UA-cam recommended your channel
I saw the title and thought I would watch it later... Until I realized it was from Huygens Optics and clicked immediately.
I really really enjoyed your videos of the mini telescope!
🙏 how are you so damn good at making these videos for us! I hope everyone grasp the deeper meanings imbedded in your work, You really are a special one!
Thought provoking and educational as always, Jeroen! I'm looking forwards to where you're going with this. I implore you to consider into your thinking the typically neglected process of EM generation by means other than orbital electrons transitioning to lower energy states: EM radiation at microwave frequencies and below, basically RF. At those frequencies, "photon" generation can't be explained in terms of orbital electron transitions afaik, and so I think by understanding the factors common to both types of EM generation, we can better grasp what a "photon" is (and isn't).
I hope I have time to incorporate the equivalence of micro- and radiowaves to visible light in the second video. If not, I'll try to make a third video. Contrary to what some want to make you believe, there is not fundamental difference between the nature of the radiation. The difference in behavior is just due to wavelength and number of discrete radiative emitters.
@@HuygensOptics I certainly hope the topic makes it into one of your future videos! The point I was attempting to make isn't that there's a fundamental difference between the various categories of EM radiation or how it's generated, but rather that the common treatment given for photon production provides pretty limited insight into the actual physics that produces these waves/photons. For example, it seems to me that an electron falling to a lower energy state explains when/why a photon is released, but not how.
Really cool video! I never considered before that if a particle travels the speed of light, the only way to have different energy states is to have it change frequency, so "slowing" light would increase its frequency and that explains how optics redirect light! Neato! :D
Dude! Are you reading my mind?? Just as I’m trying to learn more about coherence the PREMIER optics teacher on UA-cam posts a video on it!! So hyped to watch this
I do read minds occasionally, but always within the boundaries of statistical probability.
@@HuygensOptics I only read minds of Boltzmann-Brains 😆
The channel remains loyal to its name. Loved the video.
Amazing how you crush all my previous misconceptions and i am very glad of that fact
This brings me back to my Eindhoven days at the NatLab, Philips' research- and technology center, where we developed the blue LED-laser (around 1989-1990, then still only functional in a liquid nitrogen immersion) and continued to develop the red LED-laser for improvements on the CD-player. I was occupied in handling an interferometer lab-setup, measuring the beam properties and reading the Zernike-polynomials from software that was resident on HP Pascal 9000 workstations. Experienced PhD's showed us, the humble technical-college assistants, the ropes of the trade. There was no internet, only books and whatever we learned from human contact during lessons and casual conversations.
Those were the days...
Oh you slam dunked PBS Spacetime, I normally like that channel and host (and still do! They rock at explaining some wild concepts)
but that just goes to show what an absolute goat market particle physics and especially information on particle physics for laymen has become.
Also all the quantum woo I hate that.
Thanks Huygens, you are an idol and wise master to me!
Why are you so much in love with your own bullshit? :-)
Agree, this is a refreshing change. I saw some of the PBS specials with all of the quantum woo--mostly dog shite if you ask me. Fraud.
@@bustercam199 You won't find the real story anywhere on the internet. None of these people know what they are talking about. ;-)
Now this is incredibly fascinating. I love when someone can clearly present a new way of understanding concept. This one sets my imagination on overdrive. Thanks!
Wow! The most compelling video on this subject ever shown on yt. Most creators use graphics only. You, sir, build full lab grade experiments. Thanks!
Thank you very much, I'd never really understood the true meaning of coherence, in my courses we only talked about the conditions for which coherence was respected without even knowing what that really meant and now I know thanks to you!
I feel that you have come closer to explaining the "true nature" of light than just about any explanation I've run across. Is it a particle? Is it a wave? It is both, neither, and more. Light is as it is - not as the theory says. Dual nature? Sure. Extends from the macro (electricity / audio frequencies) to micro scales (gamma rays/wavelengths), why not? Reminds me of a discussion about one of Apple's latest products - that had tiny laser drilled holes for the speaker. And folks (some professional physicists with lots of letters) where stating that it can't / shouldn't work. The holes were less than 1/2 lamba of the wavelength blah blah blah! They had spent so much time with their nose against the blackboard using sine waves, trig, and calculus, as a model for what sound was they forgot what sound is - the compression & refraction of the medium through which it travels. The holes are nothing more than screen, cloth, etc. So long as they are large enough for the medium to move, sound will too. Once we truly understand (I'll borrow the term 'Grok' to mean 'true understanding') what light is, I believe we have many many more advances beyond where we are at now. Thank you for helping to advance the experimental, theoretical, and philosophical nature of this topic.
In the case of the tiny holes, they are so close together that they sound like a single source. Their sound emission is temporally coherent and at some distance, the sound will be spatially coherent as well.
Okidoki, in 7mins24sec the whole part-wave duality discussion summarized and decided. And as a bonus: it wasn't Einstein that mentioned Photons but Lewis. And.... "not for light" (double bonus thus). Never ever thought of it this way. THAT IS how a good, and above all basic, teaching is done. Klasse Jeroen, dit maakt mijn dag, verbreed mijn inzicht en zal ik nooit meer vergeten. Dank je, tnx !!
Ik voel hetzelfde!
Great explanation, congrats. I'm moving to video number 2 right now.
Finally getting the peace to watch this and the next video. Thank you.
Always very excited to see a new video on your channel. Great work as usual, hitting the sweet spot between informative and entertaining.
Wow, this helped me understand my studies on metamaterials. I know this is a part of the fundamental physics of light but presenting the concepts and experiment like this really motivates the audience to think further. Thank you!
Mind blown, and I've worked 10 years with VIS and NIR spectroscopy but you just gave me so much more understanding I wish I knew earlier :)
I wonder if you are the first UA-camr to give a decent explanation of the difference between spontaneous emission and stimulated emission.
Its great to be able to watch wave phenomena introduced with such a clarity :)
I'm always excited to see a new video from Huygens! ❤️
With you videos, I always feel like we are pondering the questions together 🤗
This channel just makes things so real.
I was waiting for this kind of explanation for years.. here I have it. THANK YOU
Finally, someone has just proved what Ive been saying for years. The M&M interferometer is NOT able to measure or compare differences in light speed. It just showing a diffraction pattern that the equipment itself has generated, like Newtons Rings pattern also does this. The interferometer is not measuring the length between the two arms by comparing the phases. The apparent phases pattern is caused by misalignment of mirrors and the splitter. Here this researcher shows that he misaligned one of the mirrors on purpose. The it all want to crap when he was able to screw the hell out of the stage and nothing at all happened to the "interference pattern". Before you go claiming that the interferometer can measure differences in light speed, you need to demonstrate that the equipment can actually do that. But no one has ever done that. There is no setup to calibrate the equipment and then show it gives a correct response to a controlled condition of a known velocity.
What a privilege to be able to watch this video. Thought provoking, thank you.
@@schmetterling4477 What part is false?
@@schmetterling4477 The guy who made the video is a expert in the field of optics, give one example where his video was wrong. Anyway his video is not bullshit far from it, a great work of science. I would watch a video made by you, please make one as good as the above.
@@schmetterling4477 "“These days, every Tom, Dick and Harry thinks he knows what a photon is, but he is wrong,” and he directly said to physicists that “Every physicist thinks that he knows what a photon is, I spent my life to find out what a photon is and I still don’t know it,” and sometimes before his death in 1955, Einstein wrote “All the fifty years of conscious brooding have brought me no closer to the answer to the question: what are light quanta? ........... Of course, today every rascal thinks he knows the answer, but he is deluding himself” (4)." The opinion of Einstein.
No course on quantum optics would answer Einstein's question to his satisfaction in my opinion. He was looking for an idea much deeper that you probably would say does not exist and I would say you are wrong.
Thanks for this. I'll be recommending this to people in the future. I'll looking forward to part 2.
I suspect you're aware of this, but when you get into the math of how to quantize the electromagnetic field, the math is usually done in terms of coherent plane waves. Observables like energy and momentum are computed in terms of quantized excitations of plane wave modes. Photons mathematically have much more to do with counting these modes than corpuscles.
Personally, I want to stay as far away from fields being quantized as I can.
@@HuygensOptics I too value realism in my physics 😉
I had thought about some of these issues for several years and you gave me some great answers. Wow thanks.
Thank you for your time and effort to make the video! Super helpful and well explained!
I really appreciate the quality of your explanations. Thanks
I chose to watch this over a SpaceX launch which was also waiting in my notifications this morning. I couldn't be happier with my decision. I am however pausing for just a bit to get a little more coffee in my system so I can be alert enough to retain the information :) Excellent content, really excellent! 100K subscriber button soon to be on its way I am sure.
Yep, watching this video requires a large number of coffee quanta.
It’s interesting to see the take of this subject with an optical perspective. I come from the land of microwaves and radio frequencies, where Doppler spectra and delay spread limit the coherence time and subsequently distance. I look forward to your demonstrations on spatial correlations, which we usually talk about in terms of angular spread.
Knowing a bit about the gaussian beam as a valid solution to maxwells equations, I expect the results will be interesting and explain a lot about the difficulty in fast optics
I like explanations that removes magic from physics using argumentes and experiments. I Like and subscribe
I am not happy to admit that I lost quite a bit of enthusiasm for this channel when you released some videos using an EM-only interpretation of quantum mechanics, and even more so when Ben Krasnow was duped by its allure as well. It seems our community has never succeeded at finding a way of presenting the wave function that feels satisfying, hence the last century of people trying to find a way around it. I applaud you for openly revisiting your interpretation and hopefully continuing to shed "light" on difficult subjects via your masterful optics perspective. Still subscribed.
Well thanks anyway for the comment. I am convinced that quantization is only in the interaction of EM radiation with matter. I'm also convinced of the fact that any quantization of energy arises from particles actually being waves. The main problem I have with quantum mechanics is that most of it does not make sense to me. Because I don't want to be able to just describe, I want to be able to understand.
@@HuygensOptics Well, that is a tough one, indeed. I am probably not the person to convince you one way or the other. I agree it is uncomfortable having to work under a theory for which we lack the sophistication or knowledge to interpret fundamentally. Hopefully one day we will. I can say that relinquishing a little bit of that sense of "knowing" is a gateway to utilizing quite a bit of predictable and repeatable outcomes which simply cannot follow from EM. If you ever feel a little dangerous, I think you would be very quick to pick up the subject. That said, I admire your colossal efforts to illuminate opaque subjects, and your insights are excellent. I also hope that I never have to go toe-to-toe with you in optics. Truly wishing you well, and interested to see what you come up with in part 2.
Intrigued. Can you elaborate on the "EM-only interpretation of quantum mechanics"?
With this and Ben's channel it feels more like taking a journey together and trying out explanatory frameworks and see where they break. A long path with lots of windings and even some U-turns.
With most other YT channels, it feels like being abruptly placed in the center of the destination and then hearing the explanation how we got there.
@@harriehausenman8623 I really appreciate this perspective. I have followed each of them since their early days on the platform, and I treasure the opportunity to watch a disciplined outsider bring fresh insights into seemingly impenetrable topics. I want to make it very clear that I have the utmost respect for this pursuit, and I think it is far easier to criticize than it is to create. The last thing I would want to do is discourage someone from an honest foray into rigorous discovery and teaching.
However, because of this, it is at very best misleading not to distinguish what one considers to be one's own speculation from that of which one is "convinced." Especially in learning quantum mechanics, there is such a temptation to find the "Eureka!" moment, students seem to be biased toward simpler interpretations over more applicable ones. If I watched these few videos as a student, I would probably have struggled to reject their premise later, because it feels so much like the missing piece of intuition.
Most of my knowledge outside of Physics is informal, but it represents the great majority of what I have learned. Rejecting explanations, trying crazy ideas, seeing where they break. I respect anyone willing to take on that journey. Trying out frameworks without a strong theoretical background requires a healthy dose of doubt at every stage, as well as a hunger for finding something that changes one's own mind. Being able to model that for thousands of others is a precious thing, and I just wanted to give a little nudge to someone I respect.
That said, I think the path Huygens Optics is on has been very fascinating. Maybe he's going to discover where the framework breaks, own up to it, and have gained 10x the understanding of someone who just believed what they were told. That would be a beautiful and rare lesson for thousands of people, showing that it is okay (and truly an advantage) to doubt everything, including doubt. My only hope is that he can share a little more of that during the journey for the people just getting started. Having a population who can access that perspective seems important now more than ever.
Amazing video.
I'm not up to snuff on my laser physics, but the results shown at the end would mean that for stimulated emission we have a much more precisely defined band gap (or whatever is between the excited state and the base state) in the material. Whereas with spontaneous emission we have a much wider range of energy gaps across which the electrons relax.
Using the equation shown at 19:15 I get a DeltaNu of 90meV. That's not a lot, but much more than I would have expected. 635nm means a 1.95eV wide "default" band gap, so DeltaNu is 1/20th of that. I wonder where the difference comes from. I know that an exciton (electron/hole pair) in a semiconductor creates its own potential well, but that would only explain deviations in one direction, a lower energy gap, so it can't be the complete answer.
I guess there is a lot of things that can contribute to spectral broadening in a doped lattice, like statistical variations in the surrounding of the emitter. Also, a variety of thermal effects should be taken into consideration, which cause exited state life time variations. And- contrary to my expectations- the transition to lasing was actually way more gradual than I expected. Anyway, this is what I measured.
@@HuygensOptics I don't see an obvious connection from the life time of the excited state to the energy of it. The statistical variations certainly contribute to the spread. I don't know enough to quantify their influence.
EDIT: So I did some research and feel kinda stupid for not thinking about it earlier...
A Laser diode is just a regular pn-diode, in a semiconductor with a direct band gap, with a current sent across the depletion region in flow direction. Until we reach the threshold voltage, aka before we begin lasing, we have only rare charges traveling across the depletion region. Those charges can either recombine across the bandgap, but they can also tunnel a bit, trading the tunneled distance for a difference in energy difference (because of the internal electric field of the depletion region, distance equals energy for charged particles). The probability of the resulting energy gap is not trivial, but I can easily imagine that this results in a gaussian distribution. 90meV are also easily explained with this. Depending on the doping concentration an electric field with 1V/50nm is easily possible (by intuition, didn't do the math), meaning 5nm would have to be tunneled which is realistic.
Thank you for pointing me to this video. I just found your channel recently and I enjoy your teaching very much.
Amazing story, looking forward to second part
And the Neutrino Muon G2 Result ( Proven by hydrogen outputs of Neutrino collisions, TempA+TempB+1ºC)
Every "Particle" is just a whole in space ;-)
Skin Theory - The Higgs velocity mechanism
General Relativity: TDR = (Temp/5)^2 seconds (+1c^3 == +1ºC)
Lorentz Gamma: TDR = V/c
Vc: TDR = (V-c)/c == (Temp/5)^2 seconds
...
So for the Muon G2 result we have ...
+3x10^8m/s == +1c^3 == +1ºC
Which implies Zero Degree Celsius space has a stationary in situ energy potential = At least the Speed of light (i.e. A distance to the the zero line of the BB space).
1c from our 3d space potential.
1c from the Velocity addition over c of the collision (**Into the BB weight space??).
1c from the depth into the BB weight space temperature aperture. (Causes a dowel like flow of space towards the Big Bang aperture binding the two space connection open)
This implies the exhibited temperature should be half input temperature because of BB space redshift (**a c^3 additive superimposed distance??).
M.B.Eringa, DrDon 1998~Jul 2022
PS: There is an implication that the interface angle between our visible space and the BB space is always 90º regardless of Visible space vector direction!.
References: DrDon; Garret; Stephen Hawking;
PPS: Garret and myself have long been discussing the top of the C^3 weight space scale.
Based on the Higgs velocity mechanism, I am thinking that the scale above the zero line on the atomic scale (i.e. our 3d space side) should be in 1c increments until the zero line and then swap to 1c,1c^2 and 1c^3 increments below the zero line. (i.e. +1c==+1ºC for speeds up to the speed of light)
The tricky thing is, the zero line is the top of the c scale, and our 3d spaces' zero line is its' weight temperature back from that zero line, so the scale should actually look like the below for a plutonium "proton" ...
+ 0c
+ 1c
...
+ 20,000c
+ 0c^3
+ 1c^3
....
+ 20,000c^3
The magnetic aperture starts at the BB space but the spacial flow "dowel" needs to go the same c distance back into our space, although it likely will collapse into a 3 dimensional sphere afterwards, the magnitude still needs to be represented on the diagram using the c scale.
So now I can say this categorically ...
Velocity based time dilation calculation
So we have V/c gives us a result in degrees Celsius.
We live at electron weight, so weight when moving matter would be 5+(V/c)
So traveling at the speed of light you have a Time Dilation Factor of (6/5)^2 or 1.44 Seconds Observed for the matters' one second.
M.B.Eringa 1981 - 2023
So much conflicting information on single photon/quanta self interference. You seem to get a different answer on every paper or experiment you read. There seems to be a huge amount of confusion on this even among the professionals and experiments. One thing I do not see talking about is that in slit experiments is the knife edge diffraction. In the related subjects there has also been a lot of misinformation on the so called on the quantum eraser and other matters. Part 2 will be interesting. Thanks for making these.
A good visualization of Schrodinger’s time dependent wave equation is the 4 minute video in the “Above Threshold” channel called “A quantum mechanics simulation with an explanation”. Although it’s a calculation of the dual slit experiment for an electron, it is very similar to the lab measurement results obtained by Huygens optics in his dual slit experiment. It even includes standing waves inside the dual slits themselves.
Simply put a masterful explanation, thank you for sharing this!
It is really strange that sometimes in science when they try to simplify things, as the result we get confusion and even more misunderstanding as with photons. Well remember when I had some problems with understanding of information theory in university due to all it's "simplifications" represented by short definitions and lots of formulas. It wasn't until I read the original articles by Claude Shannon that I understood "yes, that makes sense and is pretty simple".
I didn't understand most of this but it was still interesting! Thank you.
I am a big fan of this channel, and watch most of the videos several times (probably because I am not intelligent enough to understand the first time....!)
One of the thing with this explanation that haunts me is that an experiment with Bucky balls have shown that they too show interference patterns. How does that marry up with this explanation?
Thanks again for the significant effort you put in to create premium content.
Big Thanks to you Jeroen for this awesome good video. I appreciate all your videos but this one really stands out and try to explain some long hair content not too simplified. When looking at the wave packet it just remain me about the mathematic for Soliton equation and the behavior, that Soliton can travel through another wave or Soliton without getting distorted when it come out again, same as your two coherent light beams crossing each other. Also thanks for the music video I am a big fan.
Dankjewel Huygens! heel mooi uitgelegd, en met alle metingen en visualisering is het goed te volgen en zeer interessant!
One of the most interesting things you teased here was the question of how a particle can absorb a fixed quantum of energy from a wavefront that has spread out over a large area. You said you'd come back to that point but never did! I am deeply intrigued by that thought, so I am really hoping you come back to address that point in a later video :)
There are no particles. There are only people who didn't pay attention in high school where we have been teaching for approx. 50 years that "quanta" are small amounts of energy. The differentiation between "has" a quantum of energy "and is a quantum of energy" is absolutely crucial here. If you don't understand the difference then you will never get the correct ontology for quantum mechanics.
I don't understand. Can you explain? This was not taught in any capacity in my high school.
To be more specific: if there are no particles then... what is an 'electron'? What is a 'state' and what is a 'state transition' ? And then ultimately what is the measurement problem? Assuming this is too much to answer in a comment section, is there a video you can link that explains all these things so I can get your overall gist?
@@iestynne We have been teaching the photoelectric effect for half a century as far as I know. The photoelectric effect is an interaction between the electromagnetic field and a metal in which a photon (a quantum of electromagnetic energy) is being exchanged by the field and the solid. When taught properly no mention should be made of photons as particles because the photoelectric effect experiment is completely macroscopic and does not detect "particles" in any way, shape or form.
@@iestynne An electron is also a quantum of energy. The only complication there is that special relativity allows for two different dispersion relations, one for massive quanta and one for massless ones. This we can not teach at the high school level, not even conceptually. Once you learn quantum field theory at the graduate course level you will see why "massive" quantum fields are not a good idea. The standard model therefor uses all massless "naked" fields and mass becomes effective mass through the Higgs mechanism and couplings to other fields. Mathematically this is seriously complicated and I am not the right person to ask about the details. For that you need a theorist. I am an experimentalist. What I can tell you is that nobody has ever performed an experiment in which we have detected particles. We are only ever detecting quanta of energy. What we do see in experiments with high energy "particles" are not particles. We see particle tracks. How they follow from wave mechanics (which is not even the full theory) has been explained in 1929 by Mott, so the actual phenomenology has been covered by theory almost since day one. Very few people know about that paper, though, which leads to an endless comedy of errors about the existence of "particles".
This has been so helpful (and super interesting!)Thank you!
Best description of the photoelectric effect!
Excellent! I am really looking forward to part 2!
Just found your channel and subscribed. Brilliant work. Generating new questions...
@ 18:41 clearly these patterns are the frequency content (spectrum) of a single square wave pulse.
Is light (a photon) a pulse, and continuous light overlapping pulses cancelling out all wavelengths other than the fundamental?
Looking forward to part 2.
Thank you for bearing the torch. There is a paper on arXiv that touches on these concepts called "Do photon-number-resolving detectors provide valid evidence for the discrete nature of light?"
Thank, interesting paper. It seems that many "single photon" detectors have insufficient SNR to do accurate measurement because the noise floor can alter statistics significantly. Do you know the source of the noise? Is that thermal?
@@HuygensOptics The paper concerns "multi photon" detectors composed in a multiplexed scheme where multiple "single photon" detectors are joined through a beamsplitter network. When two detections happen "close enough" in time the result is deemed a detection of a "two photon state". At least one of the sources of the insufficient SNR is the underwhelmingly prosaic mismatch of the temporal coherence of the optical source and the so-called coincidence window for the PNR detectors (widespread in many experimental works in the literature), where the coincidence window is longer than the coherence time, therefore inflating the resultant number of "multi photon" events. You'd be surprised to see how many research groups pay no mind to simple coherence theory.
"Single photon" detector-wise the greatest impediment to a good SNR is the reset (or "dead") time not allowing high count rates. (As shown in the SNR equation)
I imagine you've encountered the cognitive resistance to even entertaining the idea of abandoning the photon (or quantized field). I can assure you that just like the phlogiston, it will die hard among the scientific community, and perhaps take much longer.
The only thing harder than discovering a certain truth about the universe is convincing other humans who are anchored and invested in the old paradigm.
At 18m12s, that picture is true if the tones are harmonically related and start at zero phase. If not, it'll look more like white noise in the time domain, with some reduced PAPR (peak to average power ratio). In RF/microwave synthesis and communication systems, there are algorithms to adjust the individual phases of multi-tone signals in order to minimize pulse trains with high peak voltages, which would otherwise drive amplifiers into highly non-linear operation.
Same at 18m39s, the phase distribution of the infinite carriers has to line up just so. A Fourier transform isn't just the power spectral density, the phase information is important too. That frequency domain plot could just as easily depict a single tone with phase&litude noise, which in the time domain would look like a sinewave with a bit of variation on the phase and amplitude.
Sure, phase information is important especially in Inverse Fourier transforms. In the images, all frequencies are assumed to have the same zeropoint for every frequency. Which of course isn't the case in spectrally broad light. Unless of course you compare the phase of every frequency with itself, as is done in the Michelson interferometer.
Love your content, your insight and the quality of the content you provide. Your view on light being a wave and NOT a particle is a rare thing these days. Keep up the great work.
We never told you that light is made of particles. We told you in high school that the electromagnetic field exchanges energy with external systems in form of discrete amounts that are called photons. That's a very, very different scenario than "particles".
Well that was illuminating.
So, it is just a wave as i was thought.
But i already changed view on topic, photon can just be a particle with varying parameter so it is creating interference by sum of parameters of many particles absorbed at one time.
You can simulate waves by field, but you can simulate waves by shortest path algorithm.
Thanks for the link to the Physics Explained channel Wave Packet video. Now I am wondering if you could make a video demonstrating the production of single photons. Simply reducing the intensity until there is only ony photon left never seemed like a very elegant solution to me. I love to ee you actually demonstrating things with real hardware !
I have for some months been trying to imagine EM phenomena as field perturbations and visualize them in my head. so far all I can handle are radio frequencies. This will help me get over the Terahertz gap ;)