Low-key top comment. 👍George Harrison was the best, most wholesome Beatle. (I said that so the public record reflects my thoughts after societal collapse) 🙃
Well then let’s move 2x the speed of light to watch this video backwards…assuming Einstein was wrong, of course, and there is no upper “speed limit” of causality.
@rodimusmaximus3912 tons of people know Captain D. He's kind of the least well known TH-cam royalty... there just isn't a ton of content that begs comparison to his, which is truly a compliment.
If you're near a gun range and closer to the target than the guns, you can hear the bullets whistling by before the bang of the gun (as most rifles shoot at supersonic speeds). I think the issue (which was also heard in your simulation) is that the hypothetical plane continues to fly and make sounds, therefore interfering with the "backwards" music produced earlier. A bullet ends at the target and thus stops making sound, so the effect is more noticeable, even in the real world. You could improve the effect in the simulated world by having the plane stop playing music once it passes over the observer
The question should be: After hitting the target can you hear the whistling wind from the bullet (which should be in reverse, so I guess it would start loud and fade away). I mean the rifle is not traveling faster than sound, it's the bullet. Your scenario might be a perfect way to test it because the bullet stopping inside the target would cease all sound coming from it. Not having spent any time sitting next to a target myself, I couldn't say but it sure sounds like fun :)
If I understand correctly, the reason this works is that the sound that was emitted by the speaker later reaches you first on the ground because the point it’s being emitted from a point so much closer to you that it takes less time to reach you than the earlier part when the speaker was further away.
I’m a musician/audio engineer turned ultrasound tech and I am not math-y. Amazing job demonstrating concepts like Doppler shift and thanks for exploring questions like this and sharing with the rest of us.
This is wild! Thank you so much for all the mathematical atrocities I'm sure you had to endure in making this video, I'll be sure to deploy my newly weaponised audio physics fact straight into the ears of anyone I can!
Bro read this and said: -I'm gonna do this but I'll add art to it too. So then he deployed his newly weaponized audio physics art&fact straight into the ears of anyone he could've.
That's interesting! One caveat of this would be that you hear two versions of the drone after the sonic boom - one version as it's approaching (but backwards, as though it were flying away from you the way it came) and the other flying away from you normally but at half-pitch.
@@melody3741 Agreed.. he did say something about it being a super quiet NASA drone. If the parameters are changed slightly and a "normal" drone was used, the sound might be more audible.
I was thinking the same, you'd actually hear both the reversed and pitched down version only once the drone has passed and they'd start simultaneously. So it would sound like it's moving forward and backward at the same time as you say
The thing is though, if the source of the sound is traveling faster than the sound, then there will be no more sound once the source has past you. The sonic boom should be the last thing you hear from anything like a plane or a bullet for example (except if the bullet hits the target near to you).
@@musicbro8225 Well, no - the source is still emitting sound, and that sound will travel backwards toward you at the normal speed of sound. It's just that the sound waves will be spaced further apart than if you were standing still. At Mach 2, that's 3x as far as they usually would be.
There's a really cool point in there that was literally just a little note on the visualisation: the sound waves invert in the 4th dimension. It isn't that they're just 'flipped' in the traditional sense; it would be closer to say the waves turned inside out, which is only possible because they don't have any tangible mass. In that sense, the sonic boom just is the interference pattern of the sound waves interacting with themselves as they get inverted.
@@lourdespachla6516 So, if you make a card with two slits in it that light can shine through and you shine a laser at it and put a screen behind, you don't see two lines of light on the screen, instead you will see bands, a fat bright one in the middle and fainter and narrower the further out. The effect can be produced with just one slit but having the two interfering lights accentuates it. The wavelength of the light interacts with the width of the slits causing a ripple effect and when the two ripples effects come together in the middle they interfere with each other, adding and subtracting rather like in phase and out of phase or harmonics. That was back when scientists were trying to prove whether light is a wave or particles; it turns out light can behave like both waves and particles. I wish I could help troywhite but my knowledge is old and sketchy.
@@lourdespachla6516 It's an experiment that shows how different kinds of observations impact the outcomes of certain phenomena on atomic and/or subatomic scales. In particular, the double slit experiment demonstrates that photons exist as both a wave and a particle. Rather than explaining more than that, I'd recommend finding a video on here to explain more if you're interested. It's a lot of complex physics, and it's easier to understand with visuals.
Just a few days ago I was out on a really quiet hill at night and saw a plane flying silently on my right overhead, and a full 30 seconds or more later I could hear the sound of the plane on my far left, on the edge of the horizon. Really interesting to have any of this explained, it’s fascinating!
Well, that is simply due to the fact that sound takes time to travel. It could have been moving much slower than the speed of sound, but it was so far away that it took longer to reach you than it did to pass your position. It's the same reason why echoes have a delay.
I have been waiting for this video for ever! Thanks so much Benn for your incredibly high quality vids. Your physics / audio deep dives are my fave. Nobody else does it like you :D
This was a great video! For me and my own hyperfixations it's great to have such a plane explanation for why the V12/V10 F1 cars sounded like they do to the crowds relative to how much they scream at a near static pitch from the driver perspective.
1:50 this is why i like hearing about concepts I already know, and that is someone will explain it in a new way and give me a whole new perspective and way of modeling how our universe works. comparing sound waves to arrows and talking about them losing energy.
I'm a dev & musician, and this one was tricky to wrap my head around. Your video does a great job of answering the question and breaking it down, thank you!
Seems like the conceptually easier way to look at this is to put the sound source at rest in the atmosphere and then move through the pressure-wave field at high velocity. Then listen to the music from the rest frame of the aircraft. This would remove or limit some of the confounding issues and it would be pretty easy to see that you encounter the waves in reverse order.
To be fair, that was the original question as well. The observer was moving at twice the speed of sound and the emitter was stationary. This does allow for the problem to be trivialized; it's far more controlled as you could then assume the observer had zero drag.
Fun fact: You can use the Doppler equations and the recording of the drone to calculate the aircraft velocity with a fairly significant degree of accuracy.
No, because why would it? Does thunder play in reverse? Do sonic booms happen in reverse? The only thing that would happen different, is WHEN you hear the sound.
I LOVE this! I started off studying the scalar science as I'm a sound healing dj looking for unique methods to improve my platform. This is really opening another world for me!
@@vjrei Regardless, I listened to him, in my free time. It was impossible to listen to the physics teacher while being forced to go to school. So I definitely learned more about this topic here than in school.
@vjrei probably true for me too but if I take away one thing I want to remember that sonic booms are when the water vapor caused by a decrease in temperature cavitates like in a bottle. I didn't know that and it's very interesting so I had to tell someone.
what a cool video :) i love how u took it so many places to get at what was interesting about the question, rather than just answering it to the letter
No, the quastion was if a loudspeaker was on the ground, and it started playing some time before the plane riches the loudspeaker. And you should listen for the ground music on the airplane, in this case sound from ground loudspeaker could be reversed, if listened from the airplane.
As someone that designs my own sounds for my music I love how you did the sound design here, especially in the 3/4th the speed of sound part. It sounded like it was actually traveling at that speed. Great job matching that up. It’s also wild to me that humans figured out how to travel that fast, but we decided against it because it sounds like an explosion and would freak people out. We went from horses and buggies to traveling so fast through the sky that it makes explosions in less than a century. Humanity is actually crazy
I’ve lived beside a busy road all my life, and always thought the sound of passing cars to be quite meditative. I’ve recently made a patch in VCV Rack to emulate the Doppler effect and inverse square law for sound intensity. It takes the perceived change of pitch and soundstage width as inputs. It then calculates the speed of the object that would create that change in pitch, and outputs individual pitch and volume CV’s for left and right channels. It’s so awesome to see someone tackle this from the sound design side of things! I might try to incorporate the sonic boom as a kick next!Keep up the great content!
I always hated physics because my teachers never were like you. What an EASY to understand explanation and absolutely perfectly visualized!!! Instant sub! 😁
Same. My physics teachers always were boring and/or extremely quickly irritated. Just throwing a bunch of formulas at you that you have to memorise, now and then a simple boring experiment with which you have to use one of those formulas, but everything always was done in such an uninteresting way.
@@MarcelNL The problem is trying to just memorize the formulas rather than trying to *understand* the formulas. Part of the reason why teaching that can be difficult is that you may lack the mathematical tools and understanding to really be taught where the formulas come from. Like the formula s = x + ut + ½at² to describe the distance traveled by an object with a given velocity and acceleration over a given time can be difficult if you just memorize it, but if you understand what ut and ½at² are and why they are there and why they look like that, it becomes much easier to remember it. But it is difficult to properly explain why it looks like that without going into integrals. So if your math studies aren't far enough that you actually understand integrals, things just get difficult to explain. Honestly, university physics was where I learned things way easier than in high school exactly because at that point I already did have the tools to properly understand what is going on. So when the teacher just started prodding into the physics of literally everything there is with the statement that when an object with velocity v travels for t seconds, it moves s meters, and then just expanded from there all the way to electrics, hydrodynamics, orbital mechanics and nuclear physics, it was actually funnily enough way easier than physics was in high school. Velocity is just the integral of position over time. And acceleration is just the integral of velocity over time. If you know that and understand what integrals are, s = x + ut + ½at² just kind of falls on your lap. That's when you *understand* rather than memorize the formula.
I fully, FULLY understand you! Actually I often asked what the formulas were based on, and that usually would make the teachers angry: "You don't need to know that! Some scientists who are far more intelligent than you have done tests and these formulas are the results of those tests so just memorise them! You don't need to know the how or what!" Same with the Sin Cos and Tan buttons on the calculator. I asked what those buttons do exactly, and again I didn't need to know that; far more intelligent people than me have made calculations and these calculations are now under that button and I just needed to know when to push that button with certain formulas that I needed to memorise. I loved chemistry and biology; that was all easy to understand but physics I really hated. Same with what we used to call Math A and math B. Math A was very simple; straightforward understandable real life examples that you had to make calculations with. The more factors those calculations had that you had to work with, the more exciting I thought it was. Math B was again with those formulas that you just had to memorise. Obey the teacher, don't ask questions. Just follow orders. Be a drone that doesn't want to grow, just function the way you need to. @@Murzac
Then you get whole body resonamce and harmonics of the medium itself.... When things start appearing here and there simultaniously... With Source moving faster than the inductance of the medium... Hence acting like light and quantum phenomena... Tranvserse across the dielectric plane of inertia... Playing forward and backwords in time simultaniously.. Excellent video. You've dived more into actual understanding of energy and matter than any agency would admit... Only thing, dense atmoshere increases permiability and rerifraction speed. . of sound as sound is medium based... Such an awesome video. Thanks for the hard work.
In L.A. I met a guy who claimed to make the first doppler fx sound for The Jetsons in the same building where my music store was. Cool video, very impressed with your math processed sound examples, and for explaining the sonic boom so well.
I liked everything in these explanations except the shooting arrrows that slow down the farther they get. It works to illustrate the idea of compressing the distance betweek waveform peaks/troughs, though, so ok. but just so folks know, the sound waves keep right on going basically forever at the same speed in their surrounding atmosphere (or media more generally) as when they are first emitted. What they lose isn't velocity, but rather energy, which over time is its power. The main reason a sound wave heard at 96 dB one meter from a speaker, which is about 1/100 of a Watt of power and as loud as a 4-beer Benn, drops to inaudibility far away is because the energy in that sound wave is spreading out over an ever-larger spherical surface, like an inflating balloon getting paler and paler as the pigment particles spread out over the stretching surface area. Eventually the energy is spread so thin that the energy _per unit area_ is below the average energy from all the other noises of our world that pass through that same little bit of area, and the original sound is masked by noise. Or if you live in an utterly silent chamber (echos or no echoes) it falls below your threshold of hearing. (A small bit of power is lost in the friction of moving air molecules, but mostly, its the spreading out that makes loud sounds quiet.) But back to the arrows! OK so I say they move at a constant speed in any chosen direction, but our fast-moving bow-hunter is simply catching up to the previous arrow with each successive _forward_ shot, and shots to the rear, each successive one is shot from further away from the prior one than if the hunter were stationary in the atmosphere around her. It's still not a perfect model because real arrows shot forward by a moving bow hunter realky will go faster than her rearward shots, but sound waves all just stick with one speed moving in any/all directions. In fact if you can understand that constant speed effect, that very clear difference between shooting projectiles and propogating waves in a medium, you've nailed the origin of the Doppler effect!!
Thanks for your efforts and a great video. Is the backwards sound played only for a moment, as you say at the end? Isn't there a continuous path of it behind the speaker, the same as there's a path of sonic boom[ing]s?
The underwater arrow analogy is very wrong. The sound is not running out of "speed" the further it gets away from the source, it runs out of _amplitude._ There's no good particle analogy for the wave nature (hence the duality) other than maybe if you shoot millions of arrows, they will have constant speed forever, but each of them has some probability to disappear from existence at any given time (tune the probability distribution to fit the 1/r² behavior, but that's just details)...
The easiest way to experience this would be to move the listener, (or a microphone) and leave the source and medium stationary. If the listener moved rapidly away from the sound source it would indeed "hear" music backwards.
If you followed the drone going 2X speed of sound playing music forward, with another drone going 2X speed of sound that had a microphone and recorded what it heard, would the music be perfectly backward continuously?
Most of the report of a firearm is from sonic booms: the expanding gasses exit the muzzle at supersonic velocities, and, for almost all rifle calibers and for some handgun calibers, the projectile is also supersonic at the muzzle. Suppressors (which don't silence a gunshot, just mitigate the volume to varying degrees) work by introducing baffles at the end of the barrel which slow down the gasses, and usually the projectile to some extent (they're pointless on supersonic calibers because the crack of the projectile is at least as loud as those of the gasses). (Trivia: a properly maintained and used suppressor will spit some of the lubricant inside right behind the projectile.) The most effective suppressor I know of (that can be verified as existing) is the integral suppressor Heckler and Koch put on some variants of the MP5 (not available to the public, only military, police, and high-end private security might be able to get them), where the sounds of the submachine gun's mechanisms are louder than the report. I've heard urban legends of a Soviet sniper rifle that was fully suppressed by way of a piston-like cartridge that didn't let the gasses escape at all, and because it was bolt-action, there was no sound made by the action, but I've seen no evidence that it actually existed.
I was still scratching my head for awhile on how does this work. Yes, I'm a bit slow. I feel like the crux of the matter was somewhat skimmed over in a few second of animation. It's there but not really explained visually. What helped me visualize this better was pausing at 7:17 and naming the last circles A, B, C, D and actually seeing in what order they got the the listener.
Astounding! I really enjoyed this. Good question "Caleb-bunch-of-numbers". Still trying to understand the Sonic Boom only happening once for each observer.
Amazing that Been actually went and replaced the atmosphere of the Earth in order to craft this experiment and show it to all of us! Sure my skin is melting off now but it's worth it!!
Question: What would happen if we sped up the play back from the loud speaker on the drone proportional to the drone's speed, assuming that 0 M/s is the "natural" state. As an alternative to creating a tungsten hellscape? We would probably have to record what the observer hears and then play it back at a regular ratio so we could hear it go backwards? Context: From what I understood we had to go into the tungsten hellscape cause we needed to fly the drone slow enough to give the loud speaker enough time to produce the alphabet, otherwise we fly over it before anything meangingful was produced.
The question makes me think of hypothetical tachyons, and how if you could see them, there would be nothing at all until suddenly two of them shot away from you in opposite directions, all purely due to doppler effects (and the tachyons outpacing light, of course).
the wave form is lagging behind the drone making the first part of the sine wave of the word being played last and the last part of the sound is played first . and the letters are also in reversing order meaning you hear D (backwards) first and A (backwards) last and then as it passes over you hear A (normal) first "in lower tone" and then D (normal) last.
Ok, so this was fantastic. ...What about orbiting bodies? There are two questions here: 1. If you are in a vehicle with a speaker, orbiting a central point, could you theoretically orbit at a specific distance and speed such that you are only able to hear the sound of the speaker as you come back around? Moving faster than the speed of sound, so you're ahead of the soundwaves of the speaker, but in an orbital velocity, so... Idk, I feel like there's something interesting there, I'm having a hard time wrapping my head around exactly how that would work. lol 2. If you are in a vehicle orbiting a directional speaker (maybe you can only hear the speaker for, say, a quarter of the orbit), how fast do you have to be going before you experience no gaps in the sound? lol
Another nice video and it's an interesting idea, but it's still theoretical. The problem is that the Doppler effect, as we know it, only works for sources with a lower speed than the wave, in our case the sound wave. At higher speeds, it still works, but it's more complex. I mentioned the wave because it can appear in light too, being a partial wave, and we can see the red shift in the galaxies. Anyway, when the speed of the aircraft is higher and it is approaching us, we hear no pitch bends. No sound will come. You already explained that. When it passes us, all the sound waves arrive at once, and theoretically, the pitch is infinite. Another problem is that when an object moves faster than the speed of sound it generates a shockwave. That shockwave is destroying our sound locally before it reaches the observer. Not really destroyed but the interference with the shockwave is what we hear as the boom. Another problem is that the sound source, or music in this case, would be so far behind a second ago that only a fraction would be able to reach us if the shockwaves didn't exist, and it would die fast from the air pressure. Theoretically, yes, on paper, those sound waves should arrive in reverse order, but that was before we actually achieved the speed of sound (19th century). In practice, it's all at once. I looked up that research paper and it's not conducted or supported by any physics universities. Further more it says "reproduced sound fields are investigated via numerical simulations" and "virtual sound sources", which is all... theoretical.
I just now realized you are The Flashbulb! How embarrassing! I've been listening to you since Kirlian Selections came out and keep stumbling across your TH-cam content and never realized there was a connection. How funny! Great content! Thanks for all the entertainment over the years!
great video I think that something great to point at is you have a visual proof right there at 7:06-7:28 where the right edge or forward traveling waves arrive in reverse order to their generation... really any speed above the speed of sound is "backwards" and 2 times is just "correctly timed/pitched".* (except not actually 100% because of drag! close enough though) if one imagines each circle as a letter you can see they're created A B C D E F but arrive F E D C B A separately interesting is meanwhile also arriving you have G H I J K in that order in a sequence determined by some factors like the ratio of speed to speed of sound, the drag/slowing effect of the medium (how quickly the waves lose speed) etc
the amount of fun in the question definitely directly correlated to the amount of fun in the video. I also liked the Fibonacci sequence shirt when talking about the whip, nice touch
When I was in the military, we would occasionally have "Air Shows" on the base. One maneuver would be a jet plane would fly well away from the crowd and then return and fly over the crowd At a speed just slightly below the speed of sound. The effect is enormous. You do not hear the aircraft at all until the plane is overhead and at a very high volume of sound. I don't know if they allow that demonstration any more because of fear of injuring people in the crowd should the plane crash into the crowd.
I've wondered about this question since college, I asked my prof but I don't think I phrased the question well so I didn't get a satisfying answer. Thanks for clearing it up so many years later!
Great video with a very interesting topic. The only problem I see is the analogy of arrows traveling underwater to explain the doppler effect. Here some confusion may arise between a change in the wave's amplitude and it's perceived frequency (or wavelength). The doppler effect arises for waves simply because the source of the wave moves at some speed and therefore the center of the next wave-front is displaced compared to the previous one. This changes the distance between the wave-fronts, which is the wavelength, when observing them. As you can see in the depiction of the doppler shifted waves in the video, this change in wavelength depends on the angle between the observer and the direction of movement (compression for angles smaller than 90° and expansion for angles larger than 90°). Now it is important to note that this has no relation to the amplitude of the wave. The effect for an object slowing down may look similar, but can be observed even if the source of the object (in the video this would be the submarine) is not in motion relative to the observer. This is not true for the doppler effect.
wouldn't you hear it both forwards *and* backwards? at 7:14 the simulation visualises the source waves that originate from before passing the observer, to eventually reach the observer in an inverted state, and the waves from *after* it has passed the observer reach the observer in non-inverted order.
Since both sound and light have a wavelength component, similar weirdness in our vision would occur as an object approaches the "barrier"......like if you could fly at 1/2 to 3/4 the speed of light past our sun, you'd see a subtle smear of a sun; red on one edge and blue on the other.....like doppler effect but for your eyes. Cuz different 'colors' are just a change in 'pitch' of visible light.
I interpreted the question to mean that the source and the medium are at the same velocity, and the observer is traveling away from the source at twice the speed of sound. Of course, that would require a mic or ear that works supersonically, and for the waves that the plane generates to be accounted for one way or another. In any case, there are at least two degrees of freedom in the problem, so we should really be answering what would happen in different domains of each
In my understanding the question is related to a situation, where you are on the plane and the speaker which plays the music is on the ground, at stationary to the air (and we assume that we eliminate somehow the wind noise of the plane without blocking the music from the outside). However its a much simpler situation with way less thing needed to take account.
An effect very similar to the doppler effect also applies to light and this is used to calculate both the speed of the expanding universe, and can even be used to calculate the distance/mass of certain stars.
Before watching the video, music (or any sound) WOULD be played backwards past the speed of sound BUT the sound source would have to move at supersonic speed in relation to YOU. So, when your distance to the sound source is constant, it would sound normal. Also, sonic boom is simply sound emitted in a longer period of time arriving at your ear simultaneously, adding up to incredible loudness, because the distance from the sound source decreases at the speed of sound.
Of course music plays backwards after mach 1... it was the SR71 pilots who clued Uri Geller in to all the hidden messages in the Beatles recordings.
Lmao
You shit posting but a wheel spins backwards... matecheck
Paul is dead. We miss Paul
Low-key top comment. 👍George Harrison was the best, most wholesome Beatle. (I said that so the public record reflects my thoughts after societal collapse) 🙃
😂😂😂 Yeah man that's it
Can't believe Benn replaced the Earth's atmosphere with corrosive gas for a video.
I know, right? But can we get a vinyl copy of his albums? nooooooo, too dangerous... X-D
Meh... we were going to dobit ourselves eventually.
My children still can’t breathe but it is well worth it!
Well then let’s move 2x the speed of light to watch this video backwards…assuming Einstein was wrong, of course, and there is no upper “speed limit” of causality.
@@markc4176 Superman (1978) is a documentary. So, should work.
You're becoming like the Captain Disillusion of the audio world.
he should paint his ears silver
@@alex0589 😂
I think this is the first time I've ever seen another soul even speak about Captain D's existence
@rodimusmaximus3912 tons of people know Captain D. He's kind of the least well known TH-cam royalty... there just isn't a ton of content that begs comparison to his, which is truly a compliment.
never heard of this channel but your comment made me subscribe :D
If you're near a gun range and closer to the target than the guns, you can hear the bullets whistling by before the bang of the gun (as most rifles shoot at supersonic speeds). I think the issue (which was also heard in your simulation) is that the hypothetical plane continues to fly and make sounds, therefore interfering with the "backwards" music produced earlier. A bullet ends at the target and thus stops making sound, so the effect is more noticeable, even in the real world. You could improve the effect in the simulated world by having the plane stop playing music once it passes over the observer
The question should be: After hitting the target can you hear the whistling wind from the bullet (which should be in reverse, so I guess it would start loud and fade away). I mean the rifle is not traveling faster than sound, it's the bullet.
Your scenario might be a perfect way to test it because the bullet stopping inside the target would cease all sound coming from it.
Not having spent any time sitting next to a target myself, I couldn't say but it sure sounds like fun :)
If I understand correctly, the reason this works is that the sound that was emitted by the speaker later reaches you first on the ground because the point it’s being emitted from a point so much closer to you that it takes less time to reach you than the earlier part when the speaker was further away.
Thank you. You just explained this better than the 9 minute video.
I’m a musician/audio engineer turned ultrasound tech and I am not math-y. Amazing job demonstrating concepts like Doppler shift and thanks for exploring questions like this and sharing with the rest of us.
This is wild! Thank you so much for all the mathematical atrocities I'm sure you had to endure in making this video, I'll be sure to deploy my newly weaponised audio physics fact straight into the ears of anyone I can!
Bro read this and said:
-I'm gonna do this but I'll add art to it too.
So then he deployed his newly weaponized audio physics art&fact straight into the ears of anyone he could've.
@@Ewr42 you better believe it!
That's interesting! One caveat of this would be that you hear two versions of the drone after the sonic boom - one version as it's approaching (but backwards, as though it were flying away from you the way it came) and the other flying away from you normally but at half-pitch.
It did show it but it was too quiet to hear
@@melody3741
Agreed.. he did say something about it being a super quiet NASA drone.
If the parameters are changed slightly and a "normal" drone was used, the sound might be more audible.
I was thinking the same, you'd actually hear both the reversed and pitched down version only once the drone has passed and they'd start simultaneously. So it would sound like it's moving forward and backward at the same time as you say
The thing is though, if the source of the sound is traveling faster than the sound, then there will be no more sound once the source has past you. The sonic boom should be the last thing you hear from anything like a plane or a bullet for example (except if the bullet hits the target near to you).
@@musicbro8225 Well, no - the source is still emitting sound, and that sound will travel backwards toward you at the normal speed of sound. It's just that the sound waves will be spaced further apart than if you were standing still. At Mach 2, that's 3x as far as they usually would be.
Your attention to detail keeps me laser focused and continuously entertained. Plus I learn stuff too!
There's a really cool point in there that was literally just a little note on the visualisation: the sound waves invert in the 4th dimension. It isn't that they're just 'flipped' in the traditional sense; it would be closer to say the waves turned inside out, which is only possible because they don't have any tangible mass. In that sense, the sonic boom just is the interference pattern of the sound waves interacting with themselves as they get inverted.
You may have just helped me figure out the double slit experiment.
@@troywhite6039umm. Whats that?
@@lourdespachla6516 So, if you make a card with two slits in it that light can shine through and you shine a laser at it and put a screen behind, you don't see two lines of light on the screen, instead you will see bands, a fat bright one in the middle and fainter and narrower the further out. The effect can be produced with just one slit but having the two interfering lights accentuates it. The wavelength of the light interacts with the width of the slits causing a ripple effect and when the two ripples effects come together in the middle they interfere with each other, adding and subtracting rather like in phase and out of phase or harmonics.
That was back when scientists were trying to prove whether light is a wave or particles; it turns out light can behave like both waves and particles. I wish I could help troywhite but my knowledge is old and sketchy.
@@lourdespachla6516 It's an experiment that shows how different kinds of observations impact the outcomes of certain phenomena on atomic and/or subatomic scales. In particular, the double slit experiment demonstrates that photons exist as both a wave and a particle.
Rather than explaining more than that, I'd recommend finding a video on here to explain more if you're interested. It's a lot of complex physics, and it's easier to understand with visuals.
No, the sonic boom is from the cavitation, the collapse of the pressure pocket when the plane flys through it.
Just a few days ago I was out on a really quiet hill at night and saw a plane flying silently on my right overhead, and a full 30 seconds or more later I could hear the sound of the plane on my far left, on the edge of the horizon. Really interesting to have any of this explained, it’s fascinating!
Well, that is simply due to the fact that sound takes time to travel. It could have been moving much slower than the speed of sound, but it was so far away that it took longer to reach you than it did to pass your position. It's the same reason why echoes have a delay.
who cares
I have been waiting for this video for ever! Thanks so much Benn for your incredibly high quality vids. Your physics / audio deep dives are my fave. Nobody else does it like you :D
This was a great video! For me and my own hyperfixations it's great to have such a plane explanation for why the V12/V10 F1 cars sounded like they do to the crowds relative to how much they scream at a near static pitch from the driver perspective.
1:50 this is why i like hearing about concepts I already know, and that is someone will explain it in a new way and give me a whole new perspective and way of modeling how our universe works. comparing sound waves to arrows and talking about them losing energy.
The amount of work on research, editing and explanation is much appreciated! Great video!
I love these science/physics vids cause you do a wonderful job of breaking it down and make the learning fun.
science is FAKE!! fake news, all fake..THE MIGHTY POWER OF JEBUS CAN EXPLAIN THIS
I'm a dev & musician, and this one was tricky to wrap my head around. Your video does a great job of answering the question and breaking it down, thank you!
Seems like the conceptually easier way to look at this is to put the sound source at rest in the atmosphere and then move through the pressure-wave field at high velocity. Then listen to the music from the rest frame of the aircraft. This would remove or limit some of the confounding issues and it would be pretty easy to see that you encounter the waves in reverse order.
To be fair, that was the original question as well. The observer was moving at twice the speed of sound and the emitter was stationary. This does allow for the problem to be trivialized; it's far more controlled as you could then assume the observer had zero drag.
Fun fact: You can use the Doppler equations and the recording of the drone to calculate the aircraft velocity with a fairly significant degree of accuracy.
that wasn't fun, it was just a fact.
New question: Fly in a circle at Mach 1 -- does the center of the circle hear a continuous sonic boom?
I think you would hear it once and then constant higher-pressure zone. Great question
I feel like he ready answered this. He said sonic boom is continuous, so yes.
this one is gonna be fun. Just finished compressible fluids class
Oof. That's some deep maths. 🤕😅
@@BennJordanThe video was great and managed to not give me ptsd. Good stuff man.
Curious viewer here. Are there types of compressible fluids other than gases?
No, because why would it?
Does thunder play in reverse?
Do sonic booms happen in reverse?
The only thing that would happen different, is WHEN you hear the sound.
Great video! Love these complex hypotheticals explained simply
I LOVE this! I started off studying the scalar science as I'm a sound healing dj looking for unique methods to improve my platform. This is really opening another world for me!
These videos are better at teaching physics than regular classrooms! Keep making them! 🙂
If I ask you about this video you won't remember a thing.
@@vjrei hehh go ask
@@vjrei Regardless, I listened to him, in my free time. It was impossible to listen to the physics teacher while being forced to go to school. So I definitely learned more about this topic here than in school.
@vjrei probably true for me too but if I take away one thing I want to remember that sonic booms are when the water vapor caused by a decrease in temperature cavitates like in a bottle. I didn't know that and it's very interesting so I had to tell someone.
@@Yoshi92 unfortunately he got several bits of physics wrong though, so you should continue trying to pay attention in your physics lectures :)
what a cool video :) i love how u took it so many places to get at what was interesting about the question, rather than just answering it to the letter
This was awesome! Not only music but also scientific content. Love it! 👍
this felt like the long version of an xkcd comic, i.e. absolutely nerdtastic!
I must admit I asked myself the same question when hearing passing sirens and thinking of the doppler effect, glad you chose this subject :)
No, the quastion was if a loudspeaker was on the ground, and it started playing some time before the plane riches the loudspeaker. And you should listen for the ground music on the airplane, in this case sound from ground loudspeaker could be reversed, if listened from the airplane.
As someone that designs my own sounds for my music I love how you did the sound design here, especially in the 3/4th the speed of sound part. It sounded like it was actually traveling at that speed. Great job matching that up.
It’s also wild to me that humans figured out how to travel that fast, but we decided against it because it sounds like an explosion and would freak people out.
We went from horses and buggies to traveling so fast through the sky that it makes explosions in less than a century. Humanity is actually crazy
It's not just because of the noise it makes. It's a compromise between speed, cost and payload/passenger capacity.
I’ve lived beside a busy road all my life, and always thought the sound of passing cars to be quite meditative. I’ve recently made a patch in VCV Rack to emulate the Doppler effect and inverse square law for sound intensity. It takes the perceived change of pitch and soundstage width as inputs. It then calculates the speed of the object that would create that change in pitch, and outputs individual pitch and volume CV’s for left and right channels. It’s so awesome to see someone tackle this from the sound design side of things! I might try to incorporate the sonic boom as a kick next!Keep up the great content!
I always hated physics because my teachers never were like you. What an EASY to understand explanation and absolutely perfectly visualized!!! Instant sub! 😁
Same. My physics teachers always were boring and/or extremely quickly irritated. Just throwing a bunch of formulas at you that you have to memorise, now and then a simple boring experiment with which you have to use one of those formulas, but everything always was done in such an uninteresting way.
@@MarcelNL The problem is trying to just memorize the formulas rather than trying to *understand* the formulas. Part of the reason why teaching that can be difficult is that you may lack the mathematical tools and understanding to really be taught where the formulas come from. Like the formula s = x + ut + ½at² to describe the distance traveled by an object with a given velocity and acceleration over a given time can be difficult if you just memorize it, but if you understand what ut and ½at² are and why they are there and why they look like that, it becomes much easier to remember it. But it is difficult to properly explain why it looks like that without going into integrals. So if your math studies aren't far enough that you actually understand integrals, things just get difficult to explain.
Honestly, university physics was where I learned things way easier than in high school exactly because at that point I already did have the tools to properly understand what is going on. So when the teacher just started prodding into the physics of literally everything there is with the statement that when an object with velocity v travels for t seconds, it moves s meters, and then just expanded from there all the way to electrics, hydrodynamics, orbital mechanics and nuclear physics, it was actually funnily enough way easier than physics was in high school. Velocity is just the integral of position over time. And acceleration is just the integral of velocity over time. If you know that and understand what integrals are, s = x + ut + ½at² just kind of falls on your lap. That's when you *understand* rather than memorize the formula.
I fully, FULLY understand you!
Actually I often asked what the formulas were based on, and that usually would make the teachers angry: "You don't need to know that! Some scientists who are far more intelligent than you have done tests and these formulas are the results of those tests so just memorise them! You don't need to know the how or what!"
Same with the Sin Cos and Tan buttons on the calculator. I asked what those buttons do exactly, and again I didn't need to know that; far more intelligent people than me have made calculations and these calculations are now under that button and I just needed to know when to push that button with certain formulas that I needed to memorise.
I loved chemistry and biology; that was all easy to understand but physics I really hated.
Same with what we used to call Math A and math B.
Math A was very simple; straightforward understandable real life examples that you had to make calculations with. The more factors those calculations had that you had to work with, the more exciting I thought it was.
Math B was again with those formulas that you just had to memorise. Obey the teacher, don't ask questions. Just follow orders. Be a drone that doesn't want to grow, just function the way you need to. @@Murzac
Then you get whole body resonamce and harmonics of the medium itself.... When things start appearing here and there simultaniously... With Source moving faster than the inductance of the medium... Hence acting like light and quantum phenomena... Tranvserse across the dielectric plane of inertia... Playing forward and backwords in time simultaniously..
Excellent video. You've dived more into actual understanding of energy and matter than any agency would admit...
Only thing, dense atmoshere increases permiability and rerifraction speed. . of sound as sound is medium based...
Such an awesome video. Thanks for the hard work.
In L.A. I met a guy who claimed to make the first doppler fx sound for The Jetsons in the same building where my music store was.
Cool video, very impressed with your math processed sound examples, and for explaining the sonic boom so well.
This is the first video of yours that I have seen. It is so well done that you got my subscription. Have a great day.
I just did the same lol
I loved this! You should do more physics videos!
The level of the models displayed in this video was outstanding! Thankyou for this amazing video
Benn Nye the soundience guy
I liked everything in these explanations except the shooting arrrows that slow down the farther they get. It works to illustrate the idea of compressing the distance betweek waveform peaks/troughs, though, so ok. but just so folks know, the sound waves keep right on going basically forever at the same speed in their surrounding atmosphere (or media more generally) as when they are first emitted. What they lose isn't velocity, but rather energy, which over time is its power. The main reason a sound wave heard at 96 dB one meter from a speaker, which is about 1/100 of a Watt of power and as loud as a 4-beer Benn, drops to inaudibility far away is because the energy in that sound wave is spreading out over an ever-larger spherical surface, like an inflating balloon getting paler and paler as the pigment particles spread out over the stretching surface area. Eventually the energy is spread so thin that the energy _per unit area_ is below the average energy from all the other noises of our world that pass through that same little bit of area, and the original sound is masked by noise. Or if you live in an utterly silent chamber (echos or no echoes) it falls below your threshold of hearing. (A small bit of power is lost in the friction of moving air molecules, but mostly, its the spreading out that makes loud sounds quiet.) But back to the arrows! OK so I say they move at a constant speed in any chosen direction, but our fast-moving bow-hunter is simply catching up to the previous arrow with each successive _forward_ shot, and shots to the rear, each successive one is shot from further away from the prior one than if the hunter were stationary in the atmosphere around her. It's still not a perfect model because real arrows shot forward by a moving bow hunter realky will go faster than her rearward shots, but sound waves all just stick with one speed moving in any/all directions. In fact if you can understand that constant speed effect, that very clear difference between shooting projectiles and propogating waves in a medium, you've nailed the origin of the Doppler effect!!
Wait a minute ... would this phenomenon apply to leslie cabients too, assuming we rotate the speaker twice the speed of sound?
Can't begin to tell you how fucking DELIGHTED i am to watch this! You Sir are hilarious in a GREAT WAY!!!
Thanks for your efforts and a great video. Is the backwards sound played only for a moment, as you say at the end? Isn't there a continuous path of it behind the speaker, the same as there's a path of sonic boom[ing]s?
The amplitude will be dropped so much by then I guess. He should do a theoretical when speed sound is just.. 10 m/s?
So is this why going twice the speed of light makes you travel backwards in time?
So basically can you do through-zero FM by moving stuff around really fast?
You just blew my mind - I think that's totes true and yet never would have thought of it in such an elegant way!
The underwater arrow analogy is very wrong. The sound is not running out of "speed" the further it gets away from the source, it runs out of _amplitude._ There's no good particle analogy for the wave nature (hence the duality) other than maybe if you shoot millions of arrows, they will have constant speed forever, but each of them has some probability to disappear from existence at any given time (tune the probability distribution to fit the 1/r² behavior, but that's just details)...
0:55 that should let you know how knowledgeable this guy is
The doppler formula is correct if you're careful with the signs in your definitions..
Jordan takes a American flag (OLD GLORY) and uses it as a rag that can demonstrate his guesses about sound waves.
Well now I need supersonic rotary speakers. Probably made of carbon fiber and superconductive wire motors. And unicorn dust because why not.
THANK YOU for finally answering one of my biggest mysteries!!! The constant sonic boom! THANKS!!!!!!!
Stumbled into this video while scrolling and found it fascinating. Definitely a well-earned hit of the bell icon
I actually have a physical copy of The Theory of Sound (volumes 1 and 2) that I got for free from my school's free book pile. Neat stuff!
The easiest way to experience this would be to move the listener, (or a microphone) and leave the source and medium stationary. If the listener moved rapidly away from the sound source it would indeed "hear" music backwards.
If you followed the drone going 2X speed of sound playing music forward, with another drone going 2X speed of sound that had a microphone and recorded what it heard, would the music be perfectly backward continuously?
"I'm equipped with many visualizations and metaphors, let's go" I'm hooked already.
Most of the report of a firearm is from sonic booms: the expanding gasses exit the muzzle at supersonic velocities, and, for almost all rifle calibers and for some handgun calibers, the projectile is also supersonic at the muzzle. Suppressors (which don't silence a gunshot, just mitigate the volume to varying degrees) work by introducing baffles at the end of the barrel which slow down the gasses, and usually the projectile to some extent (they're pointless on supersonic calibers because the crack of the projectile is at least as loud as those of the gasses). (Trivia: a properly maintained and used suppressor will spit some of the lubricant inside right behind the projectile.)
The most effective suppressor I know of (that can be verified as existing) is the integral suppressor Heckler and Koch put on some variants of the MP5 (not available to the public, only military, police, and high-end private security might be able to get them), where the sounds of the submachine gun's mechanisms are louder than the report. I've heard urban legends of a Soviet sniper rifle that was fully suppressed by way of a piston-like cartridge that didn't let the gasses escape at all, and because it was bolt-action, there was no sound made by the action, but I've seen no evidence that it actually existed.
I was still scratching my head for awhile on how does this work. Yes, I'm a bit slow.
I feel like the crux of the matter was somewhat skimmed over in a few second of animation. It's there but not really explained visually.
What helped me visualize this better was pausing at 7:17 and naming the last circles A, B, C, D and actually seeing in what order they got the the listener.
woah! .......... Your work is crazy! THANKS for this great entertainment & education + Music :D
Astounding! I really enjoyed this. Good question "Caleb-bunch-of-numbers".
Still trying to understand the Sonic Boom only happening once for each observer.
Thank you for scratching the music and science and humor itches all at the same time.
Dude, this is awesome. Great work!
Amazing that Been actually went and replaced the atmosphere of the Earth in order to craft this experiment and show it to all of us! Sure my skin is melting off now but it's worth it!!
Question: What would happen if we sped up the play back from the loud speaker on the drone proportional to the drone's speed, assuming that 0 M/s is the "natural" state. As an alternative to creating a tungsten hellscape?
We would probably have to record what the observer hears and then play it back at a regular ratio so we could hear it go backwards?
Context:
From what I understood we had to go into the tungsten hellscape cause we needed to fly the drone slow enough to give the loud speaker enough time to produce the alphabet, otherwise we fly over it before anything meangingful was produced.
10/10 for this one! Excellent video, and learned a bit of science too!
The question makes me think of hypothetical tachyons, and how if you could see them, there would be nothing at all until suddenly two of them shot away from you in opposite directions, all purely due to doppler effects (and the tachyons outpacing light, of course).
So Benn Jordan is the reason I’ve been getting drone adverts when watching music production videos.
the wave form is lagging behind the drone making the first part of the sine wave of the word being played last and the last part of the sound is played first . and the letters are also in reversing order meaning you hear D (backwards) first and A (backwards) last and then as it passes over you hear A (normal) first "in lower tone" and then D (normal) last.
This was fascinating. I don't know a thing about sound engineering/design stuff. I was entranced still.
Ok, so this was fantastic.
...What about orbiting bodies?
There are two questions here:
1. If you are in a vehicle with a speaker, orbiting a central point, could you theoretically orbit at a specific distance and speed such that you are only able to hear the sound of the speaker as you come back around? Moving faster than the speed of sound, so you're ahead of the soundwaves of the speaker, but in an orbital velocity, so... Idk, I feel like there's something interesting there, I'm having a hard time wrapping my head around exactly how that would work. lol
2. If you are in a vehicle orbiting a directional speaker (maybe you can only hear the speaker for, say, a quarter of the orbit), how fast do you have to be going before you experience no gaps in the sound? lol
Another nice video and it's an interesting idea, but it's still theoretical. The problem is that the Doppler effect, as we know it, only works for sources with a lower speed than the wave, in our case the sound wave. At higher speeds, it still works, but it's more complex. I mentioned the wave because it can appear in light too, being a partial wave, and we can see the red shift in the galaxies.
Anyway, when the speed of the aircraft is higher and it is approaching us, we hear no pitch bends. No sound will come. You already explained that. When it passes us, all the sound waves arrive at once, and theoretically, the pitch is infinite. Another problem is that when an object moves faster than the speed of sound it generates a shockwave. That shockwave is destroying our sound locally before it reaches the observer. Not really destroyed but the interference with the shockwave is what we hear as the boom. Another problem is that the sound source, or music in this case, would be so far behind a second ago that only a fraction would be able to reach us if the shockwaves didn't exist, and it would die fast from the air pressure. Theoretically, yes, on paper, those sound waves should arrive in reverse order, but that was before we actually achieved the speed of sound (19th century). In practice, it's all at once.
I looked up that research paper and it's not conducted or supported by any physics universities. Further more it says "reproduced sound fields are investigated via numerical simulations" and "virtual sound sources", which is all... theoretical.
‘The arrows in front would run out of energy faster, and so be closer together’ is conflating two things.
The Doppler effect is NOT absorption.
Good to see another demonstration of the General Relativity Theory and the Uncertainty Principle in action.
Yay Physics
I just now realized you are The Flashbulb! How embarrassing! I've been listening to you since Kirlian Selections came out and keep stumbling across your TH-cam content and never realized there was a connection. How funny! Great content! Thanks for all the entertainment over the years!
Damn coming from being a flashbulb fan, I just found out you have a really cool youtube channel. Hell yeah!
I am not into music that much, but i really enjoy learing interesting things in general, especially with teacher Negan.
great video
I think that something great to point at is you have a visual proof right there at 7:06-7:28 where the right edge or forward traveling waves arrive in reverse order to their generation...
really any speed above the speed of sound is "backwards" and 2 times is just "correctly timed/pitched".* (except not actually 100% because of drag! close enough though)
if one imagines each circle as a letter you can see they're created A B C D E F but arrive F E D C B A
separately interesting is meanwhile also arriving you have G H I J K in that order in a sequence determined by some factors like the ratio of speed to speed of sound, the drag/slowing effect of the medium (how quickly the waves lose speed) etc
Absolutely fantastic video - this kind of video is what makes TH-cam shine as a platform!
the amount of fun in the question definitely directly correlated to the amount of fun in the video. I also liked the Fibonacci sequence shirt when talking about the whip, nice touch
When I was in the military, we would occasionally have "Air Shows" on the base. One maneuver would be a jet plane would fly well away from the crowd and then return and fly over the crowd
At a speed just slightly below the speed of sound. The effect is enormous. You do not hear the aircraft at all until the plane is overhead and at a very high volume of sound.
I don't know if they allow that demonstration any more because of fear of injuring people in the crowd should the plane crash into the crowd.
coolest channel i've stumbled across in years, thank you for making me use my brain again Benn!
Great video and crystal clear explanations for someone who isn’t number savvy 🎉
I've wondered about this question since college, I asked my prof but I don't think I phrased the question well so I didn't get a satisfying answer. Thanks for clearing it up so many years later!
imagine chillin' on your lawn only to FEEL a loud BOOM from a drone whippin' by at 773mph
thank you, Ben
Great video with a very interesting topic.
The only problem I see is the analogy of arrows traveling underwater to explain the doppler effect. Here some confusion may arise between a change in the wave's amplitude and it's perceived frequency (or wavelength). The doppler effect arises for waves simply because the source of the wave moves at some speed and therefore the center of the next wave-front is displaced compared to the previous one. This changes the distance between the wave-fronts, which is the wavelength, when observing them.
As you can see in the depiction of the doppler shifted waves in the video, this change in wavelength depends on the angle between the observer and the direction of movement (compression for angles smaller than 90° and expansion for angles larger than 90°).
Now it is important to note that this has no relation to the amplitude of the wave. The effect for an object slowing down may look similar, but can be observed even if the source of the object (in the video this would be the submarine) is not in motion relative to the observer. This is not true for the doppler effect.
Note, that when I am speaking of the "center of the next wave-front", I am speaking of the center of the radial wave.
wouldn't you hear it both forwards *and* backwards? at 7:14 the simulation visualises the source waves that originate from before passing the observer, to eventually reach the observer in an inverted state, and the waves from *after* it has passed the observer reach the observer in non-inverted order.
That studio tan when outside in the sun almost blinded me
"Unless that person is me after like two beers."
I feel totally seen. Thank you, Benn, for my validation.
Since both sound and light have a wavelength component, similar weirdness in our vision would occur as an object approaches the "barrier"......like if you could fly at 1/2 to 3/4 the speed of light past our sun, you'd see a subtle smear of a sun; red on one edge and blue on the other.....like doppler effect but for your eyes. Cuz different 'colors' are just a change in 'pitch' of visible light.
I interpreted the question to mean that the source and the medium are at the same velocity, and the observer is traveling away from the source at twice the speed of sound. Of course, that would require a mic or ear that works supersonically, and for the waves that the plane generates to be accounted for one way or another. In any case, there are at least two degrees of freedom in the problem, so we should really be answering what would happen in different domains of each
This is why I love your channel
In my understanding the question is related to a situation, where you are on the plane and the speaker which plays the music is on the ground, at stationary to the air (and we assume that we eliminate somehow the wind noise of the plane without blocking the music from the outside). However its a much simpler situation with way less thing needed to take account.
An effect very similar to the doppler effect also applies to light and this is used to calculate both the speed of the expanding universe, and can even be used to calculate the distance/mass of certain stars.
Always wanted Jon Hamm to go over some practical Physics 223 with me, thanks man.
4:54 That SNAP you're hearing is the sound of "Muh Freedumb".
I’m a SR71 pilot I can confirm
This is beautiful. Thank you.
Before watching the video, music (or any sound) WOULD be played backwards past the speed of sound BUT the sound source would have to move at supersonic speed in relation to YOU. So, when your distance to the sound source is constant, it would sound normal. Also, sonic boom is simply sound emitted in a longer period of time arriving at your ear simultaneously, adding up to incredible loudness, because the distance from the sound source decreases at the speed of sound.
This was a relatively short video but felt long with all the info packed in. Super impressive.
This channel is a gem
I want that shirt, benn. merry christmas?!? oh, & supercool essay too!! yaaay!!