Impossible Muons

[@steve1978ger]

"irresponsible scientists shoot whole earth at space particles at near light speed"

[@esajpsasipes2822]

lol

[@Zaluskowsky]

Rofl

[@ItsBobbyBlitz]

@@Zaluskowsky please shut up Zalu

[@thepriestunknown3999]

From a certain perspective...

[@hareecionelson5875]

Says headline on the Mu s at 10

[@stevec7923]

This is a *brilliant* explanation of how time dilation and length contraction are simply the same phenomenon from two different frames of reference. Two sides of the same coin.

[@pabloleonjimenez]

No!!

[@parthbonde2106]

They are not two sides of the same coin so as to say.

[@stevec7923]

@@parthbonde2106 Perhaps you didn't watch the video. Time/length contraction is dependent on the observer.

[@anandsuralkar582]

Two sides of same coin earth

[@Grizzly01]

@@pabloleonjimenez Yes!!

[@thejesuschrist]

Amazing! Evidence for time dilation is awesome!

[@ssiddarth]

You are awesome 😁🤗😋👍

[@HeythemMD]

Wait... does the right check mark mean you're actually Jesus XD ?

[@aadesh_kale]

You are awesome! You might have to study a lot to create such particles.

[@lutyanoalves444]

Yo!! My maaannnnn!! :D

[@vuphihung6610]

Jesus Christ,how can you be so quick?You commented on the video just after it got uploaded for like 10 mins.Good God.

[@ReySilverskin]

The power of spacetime dilation continues to astound me. I always pictured it as applying mainly to large objects, probably because of all those thought experiments. I honestly never thought it would apply to individual particles like this. But now that I think about it, of course it would. Why wouldn't it? Science is cool.

[@ilovemathandswimming]

In soviet muon, ground reach you

[@raghavdoshi803]

You mean the ground reaches THEM

[@lunashi_e]

does that mean muons are russians and flat earthers?

[@Operational117]

Lê Xuân Khôi - James Considering a muon flying at 99.995% the speed of light lasts 100 times as long as a stationary muon, Earth, which is normally around 12000 km in diameter, would look like it’s actually 120 km in diameter in one direction, specifically the direction the muon moves toward. With that in mind, Earth, to a muon, would look like a double-sided pancake. So yeah, we can consider muons “flat-earthers”.

[@paulmichaelfreedman8334]

@@Operational117 A third perspective: The proper speed of the muon is way above light speed (Proper speed is the speed the traveller experiences and can go to infinity - the proper speed of a photon is infinite, for example). To the muon the earth doesn't look flat. It just comes at it way faster than light.

[@VishalMaharathy]

its crazy how people always make a way to make something important sarcastic. love u bro

[@spelunkerd]

For some reason I find time dilation to be easier to comprehend compared to length dilation. Shrinking of an approaching three dimensional object on only the axis of apparent movement seems, more abstract.

[@Bodyknock]

spelunkerd In a way you can think of length contraction as the reverse of time dilation. If you are stationary watching a clock moving quickly from your perspective most of the motion of the clock is in the direction of travel so less of its motion is spent relatively on the ticks of the clock, hence it is experiencing fewer ticks per minute than you experience. On the other hand from its perspective it is traveling from the same point A to point B that you see it traveling, and in its frame of reference time is proceeding the same as if it was at rest, so for it to travel that distance in the same number of ticks on its clock that you see from the outside it must be seeing the distance it is traveling as shorter than the distance you are seeing it travel. Just like in the video we see muons make a long trip with a slow clock but they see their clock at normal rate but traveling a shorter distance and both us and the muon agree on how many total ticks go by on its clock during the entire trip.

[@Videohead-eq5cy]

It's more like time dialation and length contraction are both cause and effect of each other. If time moves slower at the speed of light then you're bound to travel less distance than you seem to move and vice versa

[@ryancraigt]

Mhmm. Length contraction is essentially the biproduct of time dilation from the point of view of the moving object. Good explanations.

[@leonlupus7148]

For the sake of ease of explanation I'm gonna say that 100m/s is enough to dilate your time by a factor of two (just a bit of a stretch I know), so if you were to travel 100m/s for a second, a stationary observer would observe you travelling for two seconds. So from your perspective you had moved 100m, but the observer would see that you had moved 200m. That 200m was "contracted" to 100m for you due to your speed.

[@Blox117]

experiencing totally different rates of time isnt abstract and hard to comprehend? what are you, a time traveller?

[@hymanimy]

Literally just learnt about time dilation and length contraction in class for the first time yesterday. This helped me understand it so much more

[@renelznicolas8659]

Henry, PLEASE make a video explaining how particle detectors work!! Great job, btw. Love you

[@rajveersingh2056]

Sounds like a veritaseum episode

[@Nachoman24]

Forgot too say no homo

[@fuqin9462]

Too dumb to read the Wikipedia article?

[@pauldavis2108]

Believe it or not they are very simple. Detectors like this one in the video are scintillation detectors. When the muon passes through the detector material it gives some of it's energy to the electrons in the material, those electrons then re-emit that energy as light. Photosensors detect the light and turn itto electrical pulses which are digitized and the amplitude/time recorded so that the orginal muon path can be recreated.

[@Noname-67]

@@fuqin9462 hi not dumb person, I thought you read all Wikipedia article, why would you come here

[@bjs301]

I learned this in college decades ago. I've forgotten most of the physics I learned back then, but this always stuck with me. It's just an awesome real-world proof of relativity.

[@PabloPerroPerro]

After watching your series on special relativity, I understand this video, and it has blown my mind. Awesome!

[@flensdude]

In other words, Earth is flat! ... ... for objects moving at relativistic velocities due to length contraction.

[@josephburchanowski4636]

Yup, when moving at non-relativistic velocities from the reference of someone on Earth; the Earth is a Parker Oblate Spheroid. When moving at relativistic velocities relative to someone on Earth (since velocity can only exist relative to something else, we are technically moving at relativistic velocities relative to muons "hence why were are what contract from its point of view"). Ever try seeing if you could get someone to attack you with Ad hominems because you claimed "It is a scientific fact that the Earth is flat in some inertial reference frames" ? I always find it hilarious how people who think they are on the side of science; attack actual physics without ever realizing that they are wrong.

[@zachb99]

holy shit they were right all along lmao

[@prateekkarn9277]

@@zachb99 they won't understand shit lol

[@Crimsonraziel]

@@josephburchanowski4636 Only if you're falling towards the surface fast enough. On impact it becomes a globe again. Also running around in circles on the surface doesn't turn it into a disc either.

[@jongyon7192p]

if the earth is flat... WHY R THERE MOUNTAINS AND VALLEYS???

[@PersianMapper]

I clicked on this faster than a Muon could say length contraction

[@FaisalHusayn]

🇮🇷😘👍

[@levmarchuk998]

same

[@thomassgdf8270]

@@AstolfoGayming Were you there (not to hear them)? 🤔

[@georgf9279]

You mean "length contr..." R.I.P.

[@Blox117]

did you just assume my choice of lepton?

[@karl1ok]

Holy cow, this is an insane, and mind blowing example of real-world physics

[@koolguy728]

isnt all physics... real world physics...? isnt that the point of physics?

[@jerrymiyahtylerious2847]

@@koolguy728 ye it is the guy up there is just dense

[@karl1ok]

@@koolguy728 a lot of physics is hard to grasp, and thus I place it in the back of my head as "standard physics". This video made me acually understand how this phenomenon workes, and thus got promoted to physics I understand, aka "real world physics".

[@zodiacfml]

Actually, it really is. The topic of Muon is nothing remarkable but its properties are when compared to photons/electromagnetic radiation. If Muons decays then photons travelling at exactly the speed of light will never decay! Photons don't have a sense of time or age until it collides into something.

[@michaelwoodhams7866]

Nitpick: at 2:26 "at least 66 km before decaying" should be something like "typically 66km before decaying" or "on average 66km ...."

[@mcig98]

3:12 that stickman just turned into an *OK*

[@paulmichaelfreedman8334]

OK

[@mmixlinus]

@@paulmichaelfreedman8334 O+

[@djotter]

I saw this demonstrated at Jungfrau in Switzerland about 10 years ago. They had a reseach station detecting muons at 3500m above sea level and again closer to sea level (I think in Bern?), and at that altitude difference, the rate of detection of muons should be very different because of their half life, but it was almost identical. I don't remember if they could explain it on the information panel I read, but it is nice to hear an explanation all this time later :)

[@pascal-ox7wm]

They have a live detector on display at the Einstein Museum in Bern. It lights up every time a muon is detected - pretty cool.

[@morgansearle3912]

Just finished the first module of special relativity, and honestly this is helpful. I would appreciate it more if it also covered the peculiarities of Einstein velocity addition and exactly how Doppler shift calculations are supposed to work, because that's a REAL sticking point for basically all of us, but it was nice to see the muon dilation experiment in more concrete terms here.

[@theguyfrommars8929]

"Muons Impossible" - Starring Time Cruise and Length Contraction

[@mr.curious1714]

This is a brilliant explanation and I think the best available on youtube, and in just 4.5 minutes. I also had a doubt that *What about Muons' perspective* , many explain this, but no-one explains the length contraction in this simple way. You are the best YT channel for all these amazing science stuff to be explained in such simple way, just like legendary Richard Feynman did.

[@Nitram2810]

"The earth moving toward to at 99.995% the speed of light" Am i the only who was terrified by this mental picture??

[@hainsay]

I think it's a fairly light thought actually

[@wyattb3138]

My mind is blown thinking about that and it’s amazing that this happens in real life and isn’t crazy science fiction.

[@General12th]

HE WIPED MY FACE WITH A PLANET

[@Y337n3ss]

“vibe check”

[@nandakumarcheiro]

The earth moving towards the sun is varied as the color of sun is changing from orange red in the morning to yellow white later on.

[@xXPvPSkillerXx]

If I could just dilate the time of my weekends...

[@mmmhorsesteaks]

Gotta go fast!

[@TheMiracleMatter]

@@mmmhorsesteaks That would do the opposite, scrub !

[@mmmhorsesteaks]

@@TheMiracleMatter Not from my perspective...

[@mmmhorsesteaks]

@@JordanNexhip say jonathan and me are both wearing watches but he's really fast during the weekend. Say it's 0:00 saturday morning and weekend starts. By the time weekend's over for me; it might only be sunday morning for jonathan.

[@NielsCG]

you can do it

[@curtin-hammett]

This is insanely beautiful.

[@minomorr7399]

Omg I just learned this this semester!! You have no idea how happy this makes me!!

[@dumpeeplarfunny]

The quality of content for KZbin videos is better than college lectures, and they're better at communicating information. Too bad we can't get an entire degree presented with such professionalism and affordability.

[@danielk5338]

so myons made in the lab don't travel at that speed ? are they slower ?

[@TheAgamemnon911]

Short answer: Yes. Long answer: Lab experiments can't produce energies per particle on the level of cosmic radiation. Also, if you smash two particles in a head on collision instead of shooting one at a stationary target, the resulting particle shower is also relatively slow in the laboratories frame of reference.

[@danielk5338]

@@TheAgamemnon911 ok thx 👍🏻

[@Thrill98]

this makes no sense at all

[@WubbyPunch]

Agamemnon that was the kind of explanation that only someone who already understands, would understand lol

[@Videohead-eq5cy]

He made a mistake explaining that bit, I think. Muons are supposed to have a half life of 1.5 microseconds when they're at rest in lab frame or their own frame. So if they move at nearly the speed of light for that amount of time the don't reach very far. That's the conundrum. But if you put relativity into work, it checks out

[@Jordan-zk2wd]

Fascinating that these two factors, length contraction and time dilation, can lead to no contradictions in observations like number of particles of some type observed, despite being totally different effects. That agreement is of course baked into the spacetime interval in fundamental way, but that it can be baked into that is baffling...

[@gracicot42]

Being totally different effects? No it's the same effect. If treat time like other dimension, then time dilation is just length contraction applied to time. Time is stretched, so is space.

[@Uejji]

They're not different effects. They're the same effect viewed from different observers. In this case, we observe the time dilation, the muon observes the length contraction. We would also see the muon as length contracted and the muon would see us a time dilated, but neither of those are important for resolving the muon paradox.

[@Blox117]

the real mystery is why spacetime has these things baked into it instead of fried.

[@Jordan-zk2wd]

@@gracicot42 no, time dilation and length contraction are different. One stretches one squishes IIRC. This was covered in a previous video in his Special Relativity series. There is a comparable affect, distance dilation, for distance and another comparable affect, duration contraction (or something), for time. Also, the formulas for space and time are somewhat different, space and time have different maths applied in the Lorentz Transformation: x'=y(x-vt), t'=y(t-vx/c^2) (where y is my attempt to replace the symbol for gamma on my phone), and in the spacetime interval (ds^2=dx^2+dy^2+dz^2-ct^2). Notice the extra factors of c in both, as well as the minus sign in the spacetime interval which give's space it's hyperbolic character (noticed recently you can see hyperbola's in the space globe actually). I suppose though to be fair in natural units the c's have a value of one (sans units) which do in fact make the direction you are travelling in, x, and time, t, transform in numerically identical ways, but I would caution against simply saying time time an identical dimension which transforms the same so of course time and space are treated the same because 1) time transforms the same as the direction of travel x, not the y or z directions, and 2) the minus sign in the spacetime interval is a fundamental difference

[@gracicot42]

@@Jordan-zk2wd I stand corrected. Thank you!

[@justanotherhotguy]

KZbin is back at suggesting what’s interesting yet not even questioned at this particular second. Well, not anymore, I’m interested!

[@marcogota2325]

My physics teacher explained this beautifully to us while talking about special relativity, stuck with me for many years.

[@shreeyamittal1771]

Loved this video! First time I understood a minutephysics video in one try.

[@megaeliminator3260]

I love the *KNOWLEDGE* you provide

[@Cavething777]

sans

[@megaeliminator3260]

@@Cavething777 yea you think you are *humerus*

[@vividandlucid]

But you know what I like a lot more than materialistic things? *K N A W L E D G E*

[@4ltrz555]

*K N A W L I D G E*

[@blue9139]

Oh no don't make me shoot u with cringe blaster

[@DA-bm2mj]

I'm happy for this video's author for how he makes up a problem (that I as a non physicist didn't know it even existed) and then how he successfully solves it lol

[@saoirsemurray1310]

1:33 A touch proud that at this point I was like ".............maybe time dilation?..."

[@RedJoker9000]

Love minphysics video and paradoxes. Putting them together got you a like and a favorite.

[@kockarthur7976]

It's about time we got a video on this. Great job Mr. minutephysics.

[@ananyapathak8312]

Cats want to know about impossible meowons

[@ginnyjollykidd]

Kitten explanation of muon is simple and easy to understand.

[@fishchan5020]

Ananya Pathak LOL you killed me

[@LoopZoopler]

You're kitten me

[@oldtimer5111]

Ananya Pathak ,Schrodinger is the man to ask about that.

[@fgvcosmic6752]

I think cations are good enough for them

[@oliverkirkland420]

What's a cow's favorite particle? A moo-on! ((i'm sorry))

[@kyogrix]

Time for you to mu-ve-On

[@mr.j_krr_80]

@@kyogrix much better... Muuuuuuch BETTER

[@VocalMabiMaple]

@@mr.j_krr_80 MOOOOOOuch better

[@MattZelda]

What's a Pokemon's favorite particle? A mew-on. I'm not sorry.

[@cowthedestroyer]

Moo?

[@lachlandunn2137]

Could you use high energy muons to assist in the cold fusion of the 1950s? How would this work relativistically?

[@jubaourdja4579]

That is a very good question

[@hardeepsinghmehra520]

This makes relativity so understandable. Instead of teaching in "what-ifs" scenarios, this is what should be taught.

[@OrdinarilyBob]

This is so amazingly complicated, yet also makes perfect sense the way MinutePhysics descibes it that I'm simply gobsmacked and terribly pleased at the same time. Thanks! :)

[@abdu_jilani]

Anyone here after the recent breakthrough experiment

[@mrl9418]

Hi, great video. I gave a question : how do muons in a laboratory decay in the 2.2 microseconds (which I suppose is the time as measured by the lab) and not the same as in the atmosphere? They start out at a lower speed? Or how are they decelerated ?

[@muonnampeeti9979]

Thanks for telling me what my name means

[@timelapsehq3846]

wow 😂

[@kyilmaz2]

Amazing videos dude. Thank you. There's very little on the internet that's above my head that I can learn from.

[@uflnuceng]

In 2000 I did my bachelor's research project by making a muon telescope... thanks for the walk down memory lane.

[@TheCentrifugeChannel]

So .. I have tried how an automatic clock in my centrifuge behaves (at a g-force of 2000g). The result was obvious :D Do you think because of the acceleration (3570 RPM), the time behaves differently for a digital clock inside and outside of my laboratory centrifuge ? (because of relativity)

[@danieljensen2626]

Possibly (probably?), but for non-linear movement the situation is really complicated. You'd have to either approximate the circular path as a series of very small straight lines, or somehow invoke General Relativity. In either case I don't think there's any simple way to calculate the expected effect. And probably it would be quite small and hard to measure anyway.

[@AwkwardCheeseIsAwkward]

@@danieljensen2626 Dude, you have no idea what you're talking about. Seriously.

[@danieljensen2626]

@@AwkwardCheeseIsAwkward I'll admit that this is a weird problem and I'm not well versed in GR, but I am a physics PhD student, and I am quite familiar with special relativy...

[@danieljensen2626]

@@erazure. PhD student, don't have the degree yet, but Special Relativity only applies to non-accelerating reference frames. An object in a centrifuge is constantly accelerating, so you can't just take the magnitude of the tangential velocity and calculate the time dilation caused by that. (Obviously the tangential velocity is trivial to calculate, that's not the problem). So strictly speaking you cannot answer the question with special relativy at all. I believe what you could do though is break the circular motion up into infinitesimal linear segments, where you can sort of pretend special relativy does apply. Then you could account for the time dilation occurring during that infinitesimal movement, but you could not simply add those up, because you also have to account for the change in reference frames between every infinitesimal segment. I'm pretty sure this would be extremely non-trivial. A quick search of "relativistic rotation" on Google scholar reveals that this is actually a somewhat open area of debate.

[@danieljensen2626]

@ You can believe whatever you want man, I was just trying to answer the question. I don't actually know if that's how it's done, probably there are other approaches, that's just how I would do it. Which I bring up not to brag, but rather to say I haven't actually tried to work out the problem and I might be completely wrong. But yeah, I'm borrowing the segments thing from problems I've done where you treat linear acceleration that way, I don't actually know if it would work for rotation but it seems like it might.

[@nathanhardcastle1729]

You drew the muon with a positive charge at the begging, was that deliberate

[@MenacingPerson]

antimuon

[@ThePixelPear]

2:58 Flat Earth confirmed!

[@Owen_loves_Butters]

Technically, for a particle traveling at 0.9999999991c (might've messed up the number of 9s there), the Earth would actually be flat for them.

[@kylerossmannn]

this is the best video ive watched on youtube to date

[@vaisakhvm1726]

Awesome!!! Cheers to SR, muons, and minute physics

[@kayraaa2646]

"If you want cold fusion, you need muons and they ain't cheap." "Our world is bombarded with muons that arrive here at relativistic speeds" Hmmmmmm.............

[@tis_ace]

1g of hydrogen has like 6.023 × 10²³ particles. U need a metric shit ton(thats alot in imperial) of cosmic rays to produce even a lil bit of muons which would eventually collide with the proton and deutron whi h inturn would catalyse the nuclear reaction. But I do have a idea tho, u can use the earth's magnetic field and solar wind dynamic as a giant particle collider to generate muons and catalyse the reactors in space. Also this would greatly decrease the delta v needed to bring the He³ fuel from the moon to earth orbit. The problem would be building the reactors in space and transmission of the generated power

[@kayraaa2646]

@@tis_ace Do we have to build such a thing in space? Aurora lights start at 80km, inside our atmosphere. Building one in space wouldn't really have a huge advantage compared to building a magnetically confined fusion reactor on the ground.

[@tis_ace]

@@kayraaa2646 auroras are created when the said energetic particles predominantly from the solar wind(some cosmic rays too) are redirected by the earths magnetic field to the polar regions where they come into contact with the upper regions of the atmosphere(hence the 80 km value you gave), by idea was to situate a tokomak or other magnetically confined fusion device in the van Allen belts (the region where the solar wind and cosmic rays are trapped semi permanently) and hence lead to collisions with the confinement thermos thus creating the muons and a bunch of other things which catalyse the fusion reaction.

[@tis_ace]

@@kayraaa2646 I was banking on the fact that these particles are highly penetrative(on reasonable scales)

[@kayraaa2646]

@@tis_ace How much magnetic confinement would we need when we're using muon catalyzation too, anyway? I don't think we'd have to send an entire TOKAMAK to orbit.

[@Dimensionaught]

Are the ones created in the lab not going near the speed of light?

[@TheAgamemnon911]

not near enough to get the same relativistic effects.

[@marioa9748]

I thought the same thing. I couldn't find anything from a quick search but they have something close to 200 times the mass of an electron so I would guess muons we create in lab settings are pretty stationary. Electron's in molecules only go a fraction of the speed of light. This is all from browsing around a bit though so I could be dead wrong lol

[@attilathenun]

Mario A Min created in particular accelerators do travel at relativistic speed, but nowhere (or least very unlikely to) near the speed of light for the time dialation to really matter.

[@robinsuj]

At 95% of C the efect reduces perceived time to 31%, at 99%C it's to 14%, at 99.9% to 4.5%, at 99.99% to 1.41%; I hope you see what I'm trying to show. The effects get much larger the closer you are to light speed.

[@unk4617]

I mean they'd have to create the muons at high speed considering we usually make them by literally smashing particles together it'll be difficult to achieve muons speed since the particles which are both colliding are going near light speed so the particles they create only move at a fraction of the speed they had

[@danielg.9472]

Gps Satellite Clocks is also an elegant application of the time dilation I would say

[@Nerb1]

At 1:02 you say muon half life is 1.5mico seconds. So to detect a muon 10km into the atmosphere, you just need 4.2 million muons on their way without any time dilation. What is the frequency of muon creation?

[@GlitchedBot]

I've watched videos about this soo many times and my mind is still blown away...

[@nixel1324]

0:18 "K-On"s? Cosmic rays are weeb confirmed.

[@JarieSuicune]

@1998SIMOMEGA They are referencing en.wikipedia.org/wiki/K-On!

[@CavCave]

You're the weeb here. Get out of here. We're discussing physics here, not anime.

[@Sillimant_]

@@CavCave cringe

[@mav7677]

So... I've read some books about Einsteins special relativity theory. And there's just one thing I don't understand. For example: - system S' is moving with a speed close to c (as seen from system S). That leads to an time dialation for system S' right? but on the other side, for system S' it looks like system S is moving. So for system S' it looks like time is going slower for system S, right? Now my question is: is there even a time-dialation? Because in the twin-paradox theres just a timedialation because of exelleration. - Or is there actually something like an absolute perspective, where you can tell from that the one object is moving and the other isn't? You would really help me out if someone could explain all of this... (need to know it for a presentation). - ps: im not english... so sorry if my comment sounds stupid.

[@Bodyknock]

MAV Acceleration isn’t the reason for the twin paradox, it’s that the twin in the spaceship experiences two different inertial frames of reference versus the Earthbound twin experiencing only one frame of reference the entire time. Acceleration doesn’t enter into the calculations. There is no absolute perspective, everything believes it is at rest in its own inertial frame and there isn’t some absolute frame that everything can agree on. What is absolute is the speed of time, aka the speed of light. No matter what frame of reference you are in you will always see light traveling the same speed in a vacuum. It’s from that absolute that the rest of relativity such as time dilation and length contraction follows.

Even if it's not the right eay to think of it, i found that the frame of reference that used more energy has the actual time dilation. If you think about it, to get moving from the earth you can either put some energy to move yourself OR build massive rockets to move the earth away from you. In the second scenario, you would age faster than your twin on the earth. Here the muon has a longer lifespan because he was created by high energy beams in the upper atmosphere, while the detector did not move at all, thus not consuming any energy, to hit the muon.

[@Azzinoth224]

MAV Doug Rosengard is correct, Riccardo not. This is a common misconception about relativity, but i will try to explain it to you. There is a difference between relative and absolute quantities. Absolute quantities are the same for every observer, relative quantities are different for every observer. For example in classical physics the length of a car would be considered an absolute quantity, because for an observer inside the car it would have the same length than for an observer ouside the car watching it drive. In classical physics the length of objects is the same for every observer. The number of fingers on your hands would also be an absolute quantity, because every observer, whether or not he is moving, would agree that you have 5 fingers on each hand. Velocity would be an example for a relative quantity. The observer inside one car thinks that the car has a velocity of zero, and if there would be a second car driving next to him with the same speed, he would say that the second car has also a velocity of zero relative to him. For for an observer on the side of the street both cars have a velocity v not equal to zero. So now a good question would be: How is it possible that the same car has two different velocities simultaniously? Isn't that a condratiction? The answer is that for every observer the car has only exactly one velocity, but it can have a different velocity for every observer. Velocity is a relative quantity. But is that real? Or is one velocity actually right and it just looks like the car is moving or not moving for the other observer? Well think about it: If the observer in the first car reaches his hand out of the window and touches the second car next to him, he can do that without hurting his hand, even though the cars are driving at high speeds. So for the observer inside the first car the measured velocity of zero for the second car is totally real, with all its physical consequences. For the observer on the side of the street the situation is like this: If he reaches out to touch the car, his hand will get hurt because for him the car has a velocity, with all its physical consequences. Both observers measure different speeds, both are right and the respective speed is real for each of them. Now in special relativity the number of fingers on your hand is still an absolute quantity, but length's and times are now relative quantities. In some experiment one observer might say "My own clock is going faster", while the second observer says "No, my clock is going faster". Also the first observer claims that his car is longer, while the second observer disagrees. The above example with velocity was easy to understand, because it is intuitive from our everyday experience. With length and time it is not so intuitive, but it really is the same thing, so we can ask the same questions: How is it possible that the same car has two different length's simultaniously? Isn't that a condratiction? The answer is that for every observer the car has only exactly one length, but it can have a different length for every observer. Length is a relative quantity. But is that real? Or is one length actually right and it just looks like the car is shorter or longer for the other observer? The answer is the same as with velocity: Both observers measure different length's, both are right and the respective length is real for each of them, with all its physical consequences. The same it true for time.

[@Bodyknock]

@ It's not about using more energy either. For example, there is a variant of the twin paradox that the Fermi Lab channel has a KZbin video about involving three people all of whom travel at constant speed with no acceleration or change in direction. You get the same effect of a travelling clock leaving Earth and coming back experiencing less time than a clock that stayed on Earth but without any acceleration or differences in energy expenditure. It's simply because the out-and-back clock goes through two frames of reference while the stationary clock only experiences on frame of reference kzbin.info/www/bejne/fZjZkp2rq7ijfJY

[@altrag]

@@Bodyknock That video's explanation is.. not quite right either. The observers may not experience an acceleration, but there is one hidden acceleration involved there: When B and C cross, the time measurement has a flipped sign. In the video's graphical depiction, there's no effective difference between the description at ~7:00 and a scenario where B somehow manages an instantaneous reversal of motion at point 2, which is equivalent to a very large instantaneous acceleration. Now I'm sure mathematically that's probably irrelevant (much smarter people than me have worked on this for a long time,) but it was still a bit jarring to notice (Don's videos are usually spot on.. not surprising being Fermilab and all.) I got a "that's not quite right" vibe almost immediately but it took me quite a while and a few reruns of the video to pin down the actual problem!

[@sesemuller4086]

Shouldn’t this also help with cold fusion? The lifetime of muons should greatly increase if the muons travelled close to the speed of light. Thus, they could fuse more atoms... just sayin.

[@taints23]

Hmm

[@diane92157]

to thinking was I what is That

[@FirstnameLastname-bh9qs]

I was also considering this, but in order for Muon fusion to work, you need all of the particles to be traveling at the same speeds, which means that they share a reference frame and have the same degree of time dilation.

[@matiss234]

en.wikipedia.org/wiki/Muon-catalyzed_fusion

[@killermaster4937]

Not exactly, for a particle to travel in relativistic speeds you need to provide them with relativistic amounts of energy. So this can't help the net energy gain

[@martusins5206]

I am looking in the video at 2:26 minutes: Does the muon in the lab frame (earth) (1) travel 66 km in 2.2 micro-seconds or (2) travel 66 km in 220 micro-seconds?

[@benjohnston9455]

even with only having a laymans sense of quantum mechanics and relativity this is an awesome video to explain a few concepts in quick and easy to digest format.

[@Noxterous]

4minutephysics

[@ginnyjollykidd]

😁

[@WiredUp4Fun]

You can’t have 4minutephysics without minutephysics

[@XEinstein]

For minutephysics it's still minutephysics. He's just moving faster than you are.

[@kostantinos2297]

It's actually one minute that seems from our perspective as four due to time dilation.

[@blackflash9935]

Actually 5* Because 4:33 or 273 seconds is ~5m or ~300s rather than ~4m or ~240s (If you look at the whole video, because without the sponsorship it is closer to 4m). And even though this is a joke, for the people that are curious Henry has said that he purposely didn’t call it oneminutephysics so he wouldn’t have that time restriction.

[@ThatPsdude]

But from my perspective the Jedi are evil! :O

[@mr.j_krr_80]

So you people thought there are no "cat" stuff on this episode? The MEWons laugh at you.

[@fuxpremier]

Great video as always. There seems to me there is a small mistake at 1:12 though. If muon half-life is 1.5 μs, then after 10 μs, there should be around 1% left rather than 0.1%, shouldn't it?

[@nuzzleTOO]

yes it should...

[@robertlinke2666]

okay, that is actually really cool, and puts a sense of reality onto otherwise very abstract concepts. thnx guys!

[@stephengreen3566]

I...actually....understood this. Amazing. Great video.

[@chenlevy3773]

just for reference: at 50% light speed gamma factor is =1.15(1.00 is ordinary ) (our clock is 1.15 slower ticing then stationary clock ) at 87% gamma its 2 which means 2 times slower then stationary clock .my example for time dilation and Lorentz contraction : the distance from earth to sun is 150m kilometer (our perspective - earth frame) it takes 8 min to light reach our sun and vice versa so far so good. but from spaceship perspective (traveling from earth to sun at 87% light speed) its the rest of the world (or sun choose one) moving relative to us and the distance is Lorentz contacted by gamma 2 which means 150m kilometer(earth perspective) / 2 = 75m kilometer the new distance .and it takes 4 min to light to reach from earth to sun (compared to 8) 99% light speed is gamma 7 . (1 years in our spaceship 7 years on earth).

[@PanduPoluan]

I have to thank you profusely for this video. I *_finally_* understand about relativity theory's time dilation // length dilation. Too many books articles simply wrote that from one's POV, the other's clock seems to run slower, _and vice versa_ ... but if both are running slow against each other, they're either splitting the universe into two realities... or cancel each other ?!?!?! 😫 I give up. But your explanation of time dilation from one POV vs length dilation from the other's POV ... NOW EVERYTHING CLICKS INTO PLACE 😃 Thank you!!

[@madao7865]

I had all the puzzle pieces but still failed to put them together so the reveal just put the biggest smile on my face. You cheeky ...

[@KeithMoon1980]

This video is the first one that has made length contraction make intuitive sense. Thanks!

[@KirbyTheKirb]

This is such a quality episode, I wish it had 5million+ views, very interesting and people are missing out.

[@iloveshw]

So at what speed does is the half-life calculated and at what speed are muons created in the lab?

[@alyssag.2530]

Hey, we just talked about this in our physics lecture as an example for time dilation!

[@MigWander]

I don't know if I'm getting smarter by watching all of your videos or if this video is just simpler then previous ones, but I actually understood everything you said!

[@jamescollins4500]

That was great. I have read about the time dilation before, but I had never thought of the length contraction. Also the relativity concept of looking at an event from two (or more) perspectives. Thanks.

[@randomgoose01]

I feel so smart being able to understand all of this and actually did calculations with time dialation and length contraction

[@SreenikethanI]

This video makes SO MUCH MORE SENSE after watching thr Special Relativity series of MinutePhysics!!!

[@sasikumarannandakumar6148]

What a coincidence that this video was released just in time to help me in my particle physics test tomorrow

[@apongmamay4862]

Can you do a "minutemythology"? Your voice is just so soothing that i can't stop listening.. please consider

[@ChrisHoppe-wordmeme]

Time for a shout out thanking the channel for being awesome! 👍👍👍

[@blammular]

You should do a video just on the why's and how's of length contraction. That whole concept is crazy.

[@lunkel8108]

I think you would appreciate his series on special relativity utilising the spacetime globe, chapter 5 to be exact.

[@johnfischer1298]

This was beautiful. Thank you very much. This gives me a good base for a problem I’m working on.

[@knkspl]

Wouldn't that mean that when you are traveling at the speed of light you can go anywhere in an instant, because any distance you try to travel becomes zero? And wouldn't that mean that from our perspective (observers) whatever travels at the speed of light is effectively immortal, because for it no time passes at all (for example a 100 light years distance travel would mean for us that an object didn't get older for even a second in one hundred years it was traveling, because for object itself travel distance would be zero which would make travel time zero seconds (100 years travel time = 0 seconds object time ==> object doesn't get older => object has an infinite "lifespan"))?

[@Inexorablehorror]

Already knew about this effect, but a very nice presentation and explanation. Thank you!!

[@alexdilauro9938]

Minor math error at 1:13 ; based on the video's stated figure of a 1.5 microsecond half-life, 10 microseconds would be about 6 or 7 muon half-lives, so there would be about 1% remaining. There would be about 0.1% remaining after 15 microseconds. Other than that, nice video!

[@tylersharkey4727]

This is literally the best thing ever

[@AmitBiswas26]

At 1:37, when a muon is detected, how do you know it formed 10 km above and has traveled that distance to the detector? How do you know it didn't form just 500 meters above the detector? Do we know for sure where the muons are originating?

[@krisv8407]

Didn't know what muons were before this video but surprised by what I have learned. Great stuff!

[@straightXDspear]

I never knew special relativity was even related to muons until now. This video blew my mind!!!

[@bobinmaine1]

This was such a good video. I'm a huge physics geek, literally listen to lectures while at work. So I have had an "understanding" of time dilation and the relativistic nature of Einstein's theory, this video just connected it with reality in a way that no other has for me yet. Great job and thank you.

[@microwave221]

I got a much more intuitive feel for time/length dilation by playing velocity raptor for an hour or so. Also got motion sickness, so I guess I'm glad I don't need to deal with Lorenz contraction too often in daily life.

[@sweetzizi3060]

Thank you so much! I needed some info about muons and you gave me more than I needed!

[@174paul]

Wow! That explanation was just amazing!

[@thomasciarlariello3228]

On March 2019 at in invite only engineering conference held inside MIT"s Electrical Engineering Dept. I gave presentation on applications of muons. During the 1990s a Dr. Mitchell Swartz affiliated with MIT published my peer reviewed articles on such a topic.

[@karthikkeyansmk2727]

bro 1:30 i think why not it is formed instaneous when it hit on the detector , it could also be possible right??

[@CarTLA]

What if we replaced that muon with one of the twins? According to this video, the twin on earth woud age more, while the one falling would experience a shorter interval of time. Since we are talking about inertial frames, wouldn't this break the simmetry of velocity time dilation? I want to clarify I'm not asking about the twin paradox.

[@9753flyer]

Very well put together and explained!

[@blakewright575]

Is it not also possible that some cosmic rays penetrate the atmosphere farther than others?

[@aki_na_t0r741]

Perfect youtube alogrytm I just learned this in my Physiks Course and that is the time I see this in my Recomended vids . But really nice explanation keep that up.

[@meyerflyer34]

This is awesome. I do undergraduate research for a neutrino detector currently being built called DUNE and we have to deal with cosmic rays all the time. Fascinating stuff

[@cobblebrick]

Wait I did undergraduate research on DUNE too! What did you work on?

[@TheTechovision]

I got to do a similar verification experiment in 2nd year physics. I have to admit it was quite the mind blowing realization that SR could be confirmed in such an elegant fashion! Thank you for reminding me of this! :D