Lorentz Length Contraction in Special Relativity | Doc Physics

Unfortunately, not agreeing on how time passes also affects whether we agree on how far apart events are. Sorry!

[@TheSkyIzzBlue]

You just explained in 14 minutes what my professor couldn't explain in two class periods. Thank you very much. You, sir, are a gentleman and a scholar.

[@DocSchuster]

That's the compliment my 7th grade math teacher used to use! I'm flattered!

[@frankdimeglio8216]

@@DocSchuster The stars AND PLANETS are POINTS in the night sky. Gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites, as gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE; AS ELECTROMAGNETISM/energy is gravity; as E=MC2 is CLEARLY proven to be F=ma ON BALANCE !!! UNDERSTANDING TIME (AND TIME DILATION) PURSUANT TO THE BALANCED, THEORETICAL, AND CLEAR MATHEMATICAL PROOF THAT E=MC2 IS F=MA (OF NECESSITY): Stellar clustering ALSO proves ON BALANCE that ELECTROMAGNETISM/energy is gravity, AS E=MC2 is CLEARLY F=ma ON BALANCE. Gravity is ELECTROMAGNETISM/energy, AS E=MC2 is clearly F=ma IN BALANCE !!! This explains the fourth dimension AND the term c4 (from Einstein's field equations). Gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites, AS E=MC2 IS F=ma ON BALANCE; AS the stars AND PLANETS are POINTS in the night sky. GRAVITATIONAL force/ENERGY IS proportional to (or BALANCED with/as) inertia/INERTIAL RESISTANCE, AS E=MC2 IS F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. TIME dilation ULTIMATELY proves ON BALANCE that E=MC2 IS F=ma IN BALANCE, AS ELECTROMAGNETISM/energy is gravity; AS gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE. Accordingly, the rotation of WHAT IS THE MOON matches it's revolution. The stars AND PLANETS are POINTS in the night sky. So, it makes perfect sense that the planets will move away from WHAT IS THE SUN very, very, very SLIGHTLY. Carefully consider what is THE EYE ON BALANCE !!! (Very importantly, outer "space" involves full inertia; AND it is fully invisible AND black.) E=MC2 is CLEARLY proven to be F=ma ON BALANCE. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE, AS ELECTROMAGNETISM/energy is gravity. (Gravity is ELECTROMAGNETISM/energy ON BALANCE, AS E=MC2 IS clearly F=ma IN BALANCE.) Carefully consider what is the speed of light (c). A PHOTON may be placed at the center of what is THE SUN (as A POINT, of course), AS the reduction of SPACE is offset by (or BALANCED with) the speed of light (c); AS ELECTROMAGNETISM/energy is gravity; AS E=MC2 IS clearly F=ma ON BALANCE. The stars AND PLANETS are POINTS in the night sky !!! Indeed, TIME is NECESSARILY possible/potential AND actual IN BALANCE; AS E=MC2 is CLEARLY F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. Carefully consider what is THE EARTH/ground AND what is THE EYE ON BALANCE !!! The sky is BLUE, AND THE EARTH is ALSO BLUE. THE EARTH is a BALANCED MIDDLE DISTANCE form in relation to the speed of light (c) AND what is THE SUN (AS what is a linked AND BALANCED opposite) pursuant to the universal (and CLEAR) fact that E=MC2 IS F=ma ON BALANCE, AS ELECTROMAGNETISM/energy is gravity. The stars AND PLANETS are POINTS in the night sky. Gravity is ELECTROMAGNETISM/energy. E=MC2 IS clearly proven to be F=ma ON BALANCE. Carefully consider what is THE EARTH/ground !!! Great. "Mass"/ENERGY involves BALANCED inertia/INERTIAL RESISTANCE consistent with/as what is BALANCED electromagnetic/gravitational force/ENERGY, AS E=MC2 IS F=ma IN BALANCE; AS ELECTROMAGNETISM/energy is gravity. Accordingly, objects (AND WHAT IS the falling MAN) fall at the SAME RATE (neglecting air resistance, of course); AS ELECTROMAGNETISM/energy is gravity; AS E=MC2 is CLEARLY proven to be F=ma ON BALANCE. Gravity is clearly ELECTROMAGNETISM/energy, AS E=MC2 is clearly F=ma IN BALANCE !!! It all CLEARLY makes perfect sense, AS BALANCE AND completeness go hand in hand. Gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites, AS E=MC2 is clearly F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. E=MC2 is CLEARLY F=ma ON BALANCE. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE, AS ELECTROMAGNETISM/energy is gravity. Gravity is ELECTROMAGNETISM/energy ON BALANCE !!! (Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE. BALANCED inertia/INERTIAL RESISTANCE is fundamental.) I have mathematically unified physics/physical experience, AS E=MC2 is CLEARLY F=ma ON BALANCE !!! GREAT !!! ELECTROMAGNETISM/energy is gravity !!! By Frank DiMeglio

[@frankdimeglio8216]

@@DocSchuster UNDERSTANDING TIME AND THE CLEAR MATHEMATICAL PROOF THAT E=MC2 IS F=MA ON BALANCE, AS ELECTROMAGNETISM/energy is gravity: ELECTROMAGNETISM/energy is gravity. The stars AND PLANETS are POINTS in the night sky. Gravity AND ELECTROMAGNETISM/energy are linked AND BALANCED opposites, AS ELECTROMAGNETISM/energy is gravity; AS “mass”/ENERGY IS GRAVITY; AS E=MC2 IS F=ma. Therefore, the planets will move away very, very, very slightly in BALANCED relation to what is THE SUN. (Also, carefully consider what is THE EARTH.) Great !!! This explains the cosmological redshift AND the “black hole(s)”. GRAVITATIONAL force/ENERGY IS proportional to (or BALANCED with/as) inertia/INERTIAL RESISTANCE, AS E=MC2 IS F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. Gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE, AS E=MC2 IS F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. Gravity IS ELECTROMAGNETISM/energy. “Mass"/ENERGY involves BALANCED inertia/INERTIAL RESISTANCE consistent with/as what is BALANCED electromagnetic/gravitational force/ENERGY, AS E=MC2 IS F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity. SO, the rotation of WHAT IS THE MOON matches it's revolution; AND objects fall at the SAME RATE (neglecting air resistance, of course) !!! Time dilation ULTIMATELY proves ON BALANCE that E=MC2 IS F=ma, AS ELECTROMAGNETISM/energy is gravity !!! It all CLEARLY makes perfect sense, AS BALANCE AND completeness go hand in hand. Balanced inertia/INERTIAL RESISTANCE is fundamental. Time is NECESSARILY possible/potential AND actual IN BALANCE, AS E=MC2 IS F=ma ON BALANCE; AS ELECTROMAGNETISM/energy is gravity !!! GREAT. Stellar clustering ALSO proves ON BALANCE that E=MC2 IS F=ma, AS ELECTROMAGNETISM/energy is gravity. By Frank DiMeglio

[@ouroborosnagyok9306]

btw don’t land on Alpha Centauri..... IT’S. A. STAR.

[@RichardFeynmanRules]

Damn! What a fine presentation of time and length dilation! Bravo! Your mind experiment with Benny and Alice helped me better understand how frames of reference actually work, even though the results are not exactly intuitive or what "common sense" might say. I found the "proper length" and "proper time" explanation especially helpful. I now plan to watch the rest of your videos! Thanks!

[@SLfromknifetown]

I feel like a baby you'd just played pikaboo with - Way too happy with that enthusiastic voice of yours making things hard to intuitively understand very understandable. I think I might even subscribe. Consider me a schroedinger's subscriber. And good job.

[@Goldiney]

This has become one of my all time favorite videos. I've seen DOZENS of videos on the subject, and this is BY FAR the best. Wow. Great job.

[@hadijaffri9856]

whoever u are u cleared all the doubts in my mind and I cant thank you enough for that. The physics textbook i have had misprinted the equation of proper length as L/gamma.

[@DocSchuster]

You're quite welcome. Keep learning!

[@aremka2]

Thank you so much! I've been struggling a lot trying to understand the difference between length and proper length along with time and proper time. This really helped clarify it all for me!

[@alexneff3512]

This is amazing I couldn’t thank you more I’m doing a presentation in school on this and this really made more sense and incorporated the math better than the professional crash course video

[@subhasbagchi7008]

brilliant presentation.....no effort at all to make me understand better......i ever noticed person teaching relativity often get confused with their intuition........but you sir brilliant

[@paulg444]

The Doc operates from the stratosphere and beyond !

[@insanarafat8832]

this vid cleared a lot of things up for me.Cheers!

[@mbayliss4939]

A very thorough and methodical explanation. Thank you very much.

[@milkman4641]

Benny! Benny! Benny and the jet! Sorry...I had to. Great video!

[@wowtrax]

You are an incredible person. This makes my course make a lot more sense, thank you so much.

[@DocSchuster]

I'm so glad you liked it. YOU are the incredible person!

[@dontknow7796]

wowtrax i

[@DocSchuster]

Do the events both occur at the same place as seen by Ben-Dog? Or does Alice have that privilege?

[@pipertripp]

Nice explanation. It seems like at lot of battle is simply getting the terminology nailed down. I was very confused about who's measuring what and who's at rest and who isn't. Between you, Brian Greene, and Prof Dave I think I have the essence of it.

[@MysticMD]

You should post a video about Lorentz velocity transformation!! :)

[@munawarkarim8026]

Nice presentation - one issue I would like to point out. The requirement that both observers be on inertial frames. In the example being discussed one observer is on Earth's surface. This observer has weight that is countered by a normal reaction. The observer is not on an inertial frame. Best to have this observer in free fall to satisfy the required condition. Thanks.

[@saitharak3520]

thank you sir for such a good explanation

[@Cractoide]

Great video!

[@HamzaQayyum]

I think it'd be easier to call ∆t• (delta t naught) and L• (L naught) the shorter of the two times/distances, given that you already know length and time get shorter as your approach the speed of light.

[@godwinpaul1224]

awesome videos

[@beccateng9977]

In your previous videos, you always give the guy on earth delta t_0 and the guy in the space ship t because the guy on earth isn't moving. How come now it's the guy in the spaceship that is assigned delta t_0? I don't quite understand the explanation of the delta t_0 assignment to Alice. Thanks

[@foreverraining1522]

But what if we place mile markers from earth to alpha centauri? Alice would then be able to count the number of mile markers and arrive at the same distance that Benny does. Also, what if Alice is informed by an onboard computer which calculates distance as vt. The computer would not make the same reference-frame adjustment that we do and therefore would inform Alice of the same time and distance that Benny observes. Alice's perception of travelling a shorter distance is not the actual reality.

[@msmlcole]

lol, "at any rate"! I see what you did there ^.^

[@AdrianLParker]

I construct a train that can quantum leap. The train is 1 mile long. I drive the train into a tunnel that is closed at one end, the tunnel is half the length of my train. I have an observer at the end of the tunnel. I drive my train into the tunnel at 99.99% the speed of light. The train will quantum leap to somewhere safe the exact instant the end of the train enters the tunnel. Is the observer in the tunnel killed, or no? He observes the train being very short, but someone sat on the train knows the train's length as being double the length of the tunnel.

[@ryangrove2082]

excellent video

[@code988yay]

someone should make a video game based on a physics engine with the speed of light being a very slow number, that would be fun

[@Peacemeister]

If we are talking about car speeds, for example 100-200km/hr, how could we simplify the equation to give us a more precise decimal point of the difference between contracted and proper length. Whenever I try to plug this into my calculator it somehow assumes atomic distances are negligibly 0. Well I would like to know exactly what the atomic distances are. Ive heard of an equation saying.. Delta(L) = L_0 *[(v^2)/(2c^2)], for v

[@edtoohey4761]

+Brennan Peace This equation is indeed the small speed approximation (provided you carefully keep track of the sign so that you do in fact describe a contraction, not an expansion). Note that the conditions v

[@lilliereed8433]

As far as the formula quoted at the very beginning -- that is literally where you lost me. I thought that the formula for time where something was moving quickly was expressed by this equation: t = (gamma)((t0) -(deltax*v/c^2). Is that not the correct equation -- like is it referring to a different value of t? Or are you using an approximation without the beta term?

[@BracaPhoto]

you just kinda jumped over why the guy "stationary" in the space ship only experiences 2.53 years for alpha centauri to reach him if it's traveling at 0.87 c ... can you explain why the person in the spaceship which we are pretending is stationary thinks alpha c is only "2. whatever" light years away??

[@BracaPhoto]

also how is Benny supposedly stationary in comparison to Alpha centauri if we are moving around the sun? or are we just making that wobble negligible?

[@BracaPhoto]

my gut feeling tells me this is just all a bunch of bullshit in order to explain a few anomalies experienced in science... True physics is somehow simpler than this... Don't come at me with facts bro... haha i know "gut feeling" doesn't account for much but something is fishy going on here ! maybe it has something to do with explaining away the michelson -Morely experiments that they didn't like... didn't this Lorentz length dialation/contraction thing come about to explain that spinning table with lights experiment ?? i know that sounds like i don't know what I'm saying but still something doesn't sit right and i can't put my finger on it! God i hope someone hurries up with this unified theory thing I hear about!

[@AbuSaud.Christos]

cuze it's getting closer to him or the space between him and it is moving .. so it will shrink like if u see a spaceship moving to the left or right .. it will shrink in the direction it's moving w.r.t you

[@drakefire1800]

This is an example of trying to use math to prove science instead of using math to model science. Experiments prove science. The Lorentz transform is just a way to skew a grid with new coordinates. It doesn't prove anything when you skew perspective.

[@xalx2263]

why does delta t subzero change from being earth time to the time on the rocket?

[@RushiP5]

thank you so much! you helped me get through this unit haha

[@76BlueLions]

Thank you for the lecture. Doesn't matter also contract the more it is traveling closer to the c of light?

[@zzzoldik8749]

How about for the point view of photon it self. Length become zero because of length contraction. This is redicilious, we know photon need time to travel long distance, like from sun to earth they need 8 minute.

[@manog8713]

The problem in presenting special relativity is that the arrangements of things to get the expected answers in formal SR is arbitrary. Each observer, on Earth and on the ship, have their own proper time and proper distance. Why do you say the Earth measures proper length and not the proper time? Surely the clocks in Earth frame are all synchroneous which includes the clock on Alfa Centurie. For the Earth obser an event takes place with her own proper length and proper time, and for the ship with his own proper time and proper length. Besides, relativity is about relatibve motion and as such the only difference between the observers on earth and on the ship is that: the ship is moving away from earth from Earth perspective and alfa-centurie is moving towards the ship from ship's perspective. From the ship, the time and length would be measured in exactly the same way as earth measures about the ship moing away. And, there is no way for them to check thier measurements unless they meet again and have a chat in which case v = 0 and there is no relative motion anymore to disagree on anything. Relativity means perspective and nothing more!

[@dimensionentangled4514]

How does the length contraction stuff works? Suppose I have a arrow moving close to the speed of light. So, from my frame I see its length contracts. Now, the question is what would the contraction look like. Does the contraction start from the front end or does it start from the rear end; worst case: contracts towards the centre of the arrow?

[@jimdogma1537]

It seems to me that Benny is at rest relative to the two events, his nose is in the same place before and after the event, so why doesn't he measure the proper time?

[@deathlolo8712]

Hello again. I am still confused by the following question : Are the following situations really symmetric or equivalent ? - Benny is at rest and Alice is going @ the speed v from earth to alpha - Alice is at rest and Benny is going at speed v from the space ship It seems that you consider those two views as symmetric but in that case why Benny and Alice would experience different time.... puzzled.. Thank you !

[@DocSchuster]

Death Lolo They each see the OTHER has experiencing different times. But I do argue for symmetry here! Unless there's an acceleration...

[@deathlolo8712]

Doc Schuster Ok let's assume for symmetry. If we consider Benny's at rest Alice will age 2.5 years to reach Alpha and during this trip Benny will age 5 years. But if we consider Alice at rest and the earth is moving then it is now Benny that will age 2.5 years. So those two situations cannot be true at the same time. For me the is same issue than the twin paradox, we don't need any turn back nor acceleration to see the issue. What is strange is that this theory of special relativity is there more 100 years and it does not seem to have a simple and definitive explanation to this twin paradox. At least I did not find any. Thus I understand this creates doubt on the validity of the theory. So do you have an explanation to explain the issue with Benny and Alice and more general the twin paradox ? Thank you for what are doing. Merci !

[@Fransamsterdam]

+Death Lolo Good observation.

Has the length contraction ever been measured ?

[@jonbold]

No, no, no. Space is not a variable, Time is a variable because it is a trait of baryonic matter. Alice measures her velocity at 1.74c because her time is dilated. There is only one L. She will get there in 2.53 years by her reckoning and Benny's 5.06 years is also correct.

[@Music_Creativity_Science]

Interesting. The principle is then basically: Length = velocity ● rate of change in atoms/quarks. In her case: Length = 1,74c ● her rate of change (slowed down) in her atoms/quarks. Alice's atoms/quarks slowing down, relative to Benny, makes her travel a longer distance per such change. A hypothetical "space-kilometer" apparatus measuring her travelled distance per second in space (now moving back to seconds, which are based on certain atomic rate of change in Cesium), would show a distance factor of 1,74 for Alice and 0,87 for Benny (and therefore the same factor for velocity). So that means that the ability of her eyes to receive detailed information should decrease, the eyes become even more selective what light (of all light coming towards her) reaches her brain. Now assume that both Benny and Alice watch another very distant star (100000 light years away) while her trip is going on. This means that Alice will experience more during her life time, she will see more changes in objects (for example concerning that star), but with a lower observation frequency (less detailed) with her eyes. Like a stroboscope backwards, working slower with shorter light pulses. In other words, she "saves" changes in her atoms, and therefore also lives longer, to experience more. So, accelerate as much as you can, doesn't matter that much if you miss some photons not reaching your brain while you're awake :) Ps. Do you mean that length contraction of the object itself (the rocket) also is physically imaginary (not a variable), just a mathematical construct ?

[@rohitkumar-tw3jj]

these videos are good

[@yonahweiner]

How do you know alpha centari is moving toward the space ship at .87c from the space ships perspective? The space ship measures time differently than the earth observer, and velocity has units of length per time. If the observer on earth and the space ship don't agree on time, they shouldn't agree on velocities either.

[@DocSchuster]

Yonah Weiner The way they don't agree on distance and the way they don't agree on time cancel out their effects. This is actually extremely important - there's symmetry in me watching you or you watching me. Since there's no actual framework or grid for motion in the universe, relative velocities are the only thing we have.

[@yonahweiner]

Doc Schuster So do we have to assume there's symmetry in regards to velocity? Is that something we just know empirically? Maybe there's no change in the relative lengths (by length contraction), but there is a change in the relative velocities.

[@DocSchuster]

Yonah Weiner I can't see it being logical any other way. If I think you're going 0.8c north, you have to think I'm going 0.8c south. Can you explain how it might be different? I can't even imagine.

[@zanescheepers2084]

So, length contraction actually refers to duration from the traveller's perspective, not actual physical distance?

[@deathlolo8712]

Awesome videos ! well done, I like the rythm. In 10 min you can explain clearly complex ideas ! I still need to understand one point : - in your thought experience you assume that both Alice and Benny agree on Speed. As they disagree on length and time why would we assume that they agree on the speed ? Merci !

[@DocSchuster]

Death Lolo That may be a deeper question than it seems. But you can run the numbers for each of their measured times and distances covered for the other guy and find that they measure the same speed, but opposite directions. Additionally, since there's symmetry, it would be weird if they calculated different speeds - whose would be faster?

[@deathlolo8712]

Thank you again. This helps !

[@affafqureshi2710]

I found your lecture very helpful. Still I was not able to understand why alice experiences any distance as say she finds herself at rest

[@anoirtrabelsi8645]

Can we derive the length contraction formula using the relativity of simultaneity ?

[@AbuSaud.Christos]

but what if we want to measure the time that passed on earth with respect to the spaceship ? it will be 1.3? is that normal ?

[@sakibgazi1124]

but light would experience time normally just like a reference frame traveling close to the speed of time. its just that from our perspective light would not experience any time right ?

[@DocSchuster]

+Sakib Gazi YES! Important distinction. Light would see US as experiencing no time. [which is, of course, wrong...from my perspective!]

[@phy6er956]

Hey....plz tell me how was my video on time dilation and relativity and derivation of e=mc2...

[@benjaminkilleen5525]

What does light experience when it goes through a medium of n greater than 1? What about a Bose-Einstein Condensate? Does it still experience no time?

[@DocSchuster]

Wow. Fun. You need to study group velocity and phase velocity under the broad topic of dispersion. I just read, however, that the speed of the wavefront is always c, regardless of the medium's n. So, light still feels no time as seen by us...but it thinks we feel no time...heh.

[@ananditagurung2974]

What is proper length of a rod ?

[@thedreamthieves7987]

can u explain how .87c makes gamma equal 2 just a little confused

[@DocSchuster]

The Dream Thieves Define gamma.

[@souravguha1017]

The Dream Thieves v=0.87c beta =v/c beta=0.87 gamma =1/sqrt(1 - beta^2) which nearly equals 2 :)

[@matrixate]

+The Dream Thieves Set gamma, by itself, equal to 2 and solve for v. Done. You get ((sqrt3)*c)/2. That is ~ equal to 0.86602c

[@AstrophysicistBryan]

Nice lecture. One concept I can't process is at 7: 28 where you mentioned "proper time" is "relative to 2 events".....what "events"... Otherwise, wow. I guess I might as well skip grade 12 physics and learn this instead. :-)

[@DocSchuster]

Aha. An event is simply something that happens at a certain place and a certain time. A lightning strike hitting the ground, maybe, or a hand clap.

[@AstrophysicistBryan]

hm.....I think I'm starting to understand it....thanks :-)

[@user-tm9eo9rv2r]

shit, this dude just calculated 4.4/0.87 without calculater

[@bob123789456]

i'm confused. if light doesn't experience time, why does it still take 8 minutes for it to reach earth from the sun? and what's the point of a lightyear in that case?

[@DocSchuster]

That's what you see - not what light sees.

[@bob123789456]

so even though light doesn't "experience" time, it still takes the light 8 minutes nonetheless? and i'm still confused on how a lightyear works then

[@DocSchuster]

You'll need to reflect more on the fact that there are always at least two observers in relativity problems. In this case, Einstein wants you to consider light and YOU as the observers. Light can't experience time, but YOU think that light does take time to do stuff. In fact, you think it goes 3e8 m/s. So, how far does it go in YOUR year? (answer in meters)

[@bob123789456]

oh ok, i kinda get it now. so then is there essentially no such thing as absolute time?

[@DocSchuster]

Now we're talking!

[@rdbrewer4]

"It's time we let x solve for itself." --y

[@Grejegando]

Why do I think that relativity is completely a philosophical issue rather than a scientific one?! What the hell did I just watch? It took Alice the same "proper time" to reach Alpha Centauri from my perspective (I am on Earth). And from Alice's perspective it also took Alpha C. the same "proper time" to reach her rocket. Where is the problem then? The problem is when you said that I was looking at Alice's clock inside the spaceship and I observed it to be slower than the clock I had on earth. Is that what complicated the matter here? Is this where the puzzle lies? Is this your way of bringing time dilation into this scenario? I don't understand where the problem is. I just think there's no problem in the first place. We are trying to make sense of a scientific mistake called Special Relativity.

[@shitolchayastudio2969]

From Bangladesh.

[@deevya]

good video anand sent me

[@peat11]

If only this bullshit was true my 6 hour journey each year to Cornwall would only be three but alas it is always six but feels like nine.

[@jean-lucethelenedelvaux-hu7211]

so bad that very few people explain from where the lorentz transformation comes from and here again it is considered as it come from god aldo it ist not. After, all the explanation shown in this video is like ridiculous

[@sahidaislam3237]

it is not bengali.plz plz

[@nicholasmartin6353]

Wow, you talk fast, but fun video!

[@qualquan]

no good

[@RTD553]

Not a convincing derivation.

[@stevegovea1]

Great video!