minutephysics - 2018-04-03
Go to http://brilliant.org/MinutePhysics for 20% off a premium subscription to Brilliant! Mark Rober's youtube channel: https://www.youtube.com/markrober The previous videos in this series: Chapter 1: Why Relativity is Hard https://www.youtube.com/watch?v=1rLWVZVWfdY& Chapter 2: Spacetime Diagrams https://www.youtube.com/watch?v=hTxWAQGgeQw This video is chapter 3 in my series on special relativity, and it covers boosts, galilean transformations, newtonian relativity, and of course Lorentz transformations, the constancy of the speed of light, relative changes of velocity between inertial reference frames, etc - some of the stuff Einstein figured out. I introduce the mechanical minkowski diagram, aka mechanical Lorentz transformation, aka spacetime globe. Support MinutePhysics on Patreon! http://www.patreon.com/minutephysics Link to Patreon Supporters: http://www.minutephysics.com/supporters/ MinutePhysics is on twitter - @minutephysics And facebook - http://facebook.com/minutephysics And Google+ (does anyone use this any more?) - http://bit.ly/qzEwc6 Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Created by Henry Reich
"Assume the cat moves at a third of the speed of light" that is one speedy little kitten
And what the HECC did he do to the cat?
so you mean any cat at 3 am for no reason?
But it's a perfect sphere, so that's OK.
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.
Yeah I noticed that too
So Henry is not just abusing cats like Schrödinger did, he's mistreating sheeps as well.
Good one!
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.
Only by the current 'understanding' which is incomplete. Science is infamous for throwing out plausible or even very real ideas because it isn't convenient for them.
"Minute Physics"
Legit uploads a 12 minute video 😂😂
It's still in minutes not hours
Time spans depend on the observer 😂
@Bjowolf2 yes, time is relative XDDDK
@erik zalan szabo It's really the PROJECTED (observed) part or component of the length of an object that shrinks - and "back projected" time that expands (dilates) - NOT their actual length and time themselves!
The factors of the Lorentz-transformations are really cosines, if you look at them in the right way.
sqrt ( 1 - v^2 / c^2 ) etc. - think of a circle with the radius c.
If you think of these as complex values ( i.e. a two dimensional time plane etc. ), it becomes easier to understand.
So the two observers don't really have the same time ( paths or "directions" ) in the first place - their real ( or imaginary? ) time axis ( experienced time ) appear to be rotated in relation to each others. This way there are no weird paradoxes at all.
Having a velocity relative to another observer really means that you are partially "out of" his or her spatial and temporal dimensions ( 3 + 1 complex (!) dimensions ) - and vice versa.
Is it minute or minute. Change your perspective.
Major sudden realization: The speed of light is the eigenvector of the Lorentz transformation!
The Lorentz factor 1/ gamma = sqrt ( 1 - (v/c)^2 ) - i.e. the amount by which a length of a moving object ( with velocity v along the x-axis relative to an observer ) contracts from the perspective of the observer - looks suspicially like a cosine, if you interpret it geometrically ( a velocity unit circle with c = 1, and v along the y-axis (!) ).
So in this image this Lorentz contraction is really a sort of projection on to the x-axis of the observer - the length doesn't actually shrink, BUT its projection does (!) - more and more so as v approaches the upper speed limit c, and 0 for v = c.
So the faster the object moves, the more its projection - or its presence rather! - along the x-axis of the observer contracts - the faster the object moves relatively to an observer, the more it is out of his / her spatial dimensions ( x - axis in this case ).
Maybe we need to start thinking of time and length - and thus speed - as complex (2D) variables?
Is it light speed or rate of induction. How does light speed up after traveling through glass? Did the speed change or the rate of induction?
Yeah, I just had that revelation too.
@ConradsStudio Thank you so much for the video recommendation. Subscribed 3B1B now.
The determinant of the transformation is 1. Kind of makes you think, what is preserved?. ;)
You explained the idea of Special Theory of Relativity so easily that I wish you were one my profs teaching me in college. I had to read so many books and visualize so much to understand the intuitive ideas of relativity, wish I had got this video in the 2nd year of my college... terrific job dude...
@Divyajyoti
I couldn't handle this guy's voice for more then two minutes, let alone everyday in a classroom.
Honestly tho I think the journey of you reading through all that and struggling internally to visualize and understand, while incredibly painful and tedious, is still well worth while, and something a lot of learners avoid at their own peril.
No joke, I understand everything now. In the first minute of the video I understood the fourth dimension. This is the best video ever.
hey Henry can you put the time-globe for sale?
Yeah I'll fight someone for one
OK, one more comment to say the same thing, but... I'M READY TO BUY THE DEVICE, BUILD A COMMERCIAL PAGE MATE! (Mark Rober, I mean... By the way, great job as usual, minutephysics! :) :) :) )
I honestly just memorized this so I can make my friend’s brain hurt
A Youtube channel for you was a smart move, because you wouldn't be making the money you make as a physics teacher. :-)
Oh! So the 'c' stands for cat!
8:08 .. the sheep is moving 50 percent of the speed of light in that example 🤯
speed of light = c
c for cat
boom.
quick physics
What about the cats’ perspectives? How do you transform that?
I thought c is for cookie.
Boom
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.
just a 2 cents about the change of different spacing of the cat after the transformation. The speed stays the same but the wave length of light changes similar to doppler's effect.
"Suck it, Sheldon! An engineer did this." - Howard Wolowitz, circa 2018
...I think...
All the best scientists were engineers
i want a time globe!! seriously, can i buy one?
I clapped my hands whenever I understood something
then I realized I wasn't the only one in the restaurant.
xD
I thought my sound wasn't working at the start - and then I had my ears blown off 5 seconds in after trying to turn up the volume 🙈🙉
+KarAT Feng Yeah she's the new Master Therion :D
@KarAt Feng its called marketing
Rule 1 is that there's a special place in hell for people with channel intros longer than 10 seconds on every video they make.
I've been having an issue with youtube recently where sound doesn't work on some videos consistently. It really threw me off here.
Rule #5 or something of video watching. If you ever suspect your sound might be broken, pause the thing you are watching and start up something else you know usually works, like an audio file. If that works like normal you can open up another browser window to see if it's your browser acting up. If that also works like normal it's probably the video or player that is silent/muted.
That was beautiful, really showing how the speed of light is an eigenvector in these diagrams
just had a final exam over this and more. and this pops in my recommended?
coincidence? i think not!
They are listening!
Nobody:
Me: 4d Lorentz Machine to describe 3 dimensions + 1 time dimension transformations.
At the 8 Minute Mark: couldnt that be also explained via linear algebra in terms of eigenvalues and vectors?
This has been one of the best explanations of Lorentz transformations I have ever seen. I want you to know that.
Wow, good job Mark Rober! Hats off to you, Mr. MinutePhysics guy.
Oh, I see.
There are hyperbolic rails keeping the product of the eigenvalues constant.
c².
😵
Truly, cats can make understanding Special Relativity easy.
MINDBLOWN. I've known that "time slows down when one moves faster" but I'm now starting to see why.
I clicked on this with the speed of cat
Were you transformed?
Paul Paulson Alive or dead?
momiaw - indeterminate.
Speed of light: C. First letter in cat: C.
Coinkydink? I think not.
Simon Clarkstone Becase the c obviously stands for cat.
"Time globe" sounds like something from Doctor Who. I approve.
7:33 is "(more on this later)"
10:30 actually i find the equations less confusing
7:33 More on this Later,
For anyone wondering.
I'm a physics and math instructor. Any way I could get my hands on one of these Time Globes?
I think before it is mass produced, some time should be spent on discussing it's pros and cons and how to improve its function and usefulness even more, if such is possible, and reduce manufacturing costs. But in the video, it looks amazing for a prototype. It would make a great Kickstarter project for sure! The metal version looks beautiful, but I'd settle for a wooden version, or even molded plastic, were it more affordable.
well, you can just use the actual Lorentz transformation in python (or your preffered coding language) for a grid like that to map out how it's going to look ... then you can just take out those values and interpolate the curve ... i think Bezier should do just fine ...
3D printing seems like a good option. It's possible to cheaply print linear bearings which are good enough for something like this, and they would be the most expensive part otherwise I think. You could do it on a much smaller scale as well, using plastic rod or wooden dowel even.
yes, but it's the tactile part and actually feeling the thing as yo work it. Besides, great desk ornament.
Elliot Jenner
please sell this in a merch store so peeps like me taking this in class would be helpful
I thought coordinates were (x,y) but at 3:13 you're doing (y,x)
"squeeze rotation" IT'S A SKEW
7:50 squeeze rotationy things!!🤣🤣🤣🤔
me: pauses the video to read the small remarks
youtube: places the navigation bar and play/pause controls over the text, without any way to dismiss them
Go out of full screen.
Or go out of widescreen mode.
or Henry could just make pointless messages to the viewer last more than 1 frame so you don't have to interrupt the video for no reason lol
Yeah view it on your iPhone rather than web browser so get around it
if u r on mobile it's better because you can pause and then tap to hide the statusbar and controls ... this is also really neat for taking screnshots
Nah, you need to work on your speed reading skillz
Very good explanation and I love the time globe. Thank you.
8:53 He's saying number of speed of light in speed of light.
And that is how time dilation causes the speed of light to stay the same
When I was in college a decade ago, doing my CS degree, I would have loved to have videos like this that helped me understand why I was learning certain mathematical functions. I was always very good with math until I got to portions of calculus and then linear algebra. The math involved became so abstract, I could not connect the application of the functions, which for me, hindered my understanding and ability to learn. I know many people have different learning styles, of which, none of the methods apply to me (verbal, written, etc. are the same), but without understanding the application, my mind becomes limited. These videos would have been great primers for aiding my understanding. I never used the "high-level" math that I learned when programming, but learning should never cease, so I greatly appreciate videos of this nature.
11:00
Me, trying to be better at Dart Game : practice...
Mark Rober : I HAVE AN IDEA...
Wait a minute, could you start again from the part about the cat, I lost you around after that :-)
Still hurts my head. Probably should rewatch several times when I am at a better mental state.
https://www.youtube.com/watch?v=6zWy6_Mog70 This will clear it all up
Even after such beautiful explanation, i am still at sea...
E=mC^2 where the C represents the constant velocity of cats in a vacuum?
@whuzzzup So the meow approaches infinite as the cat approaches infinity? Ouch! The real question is, "How can you be 'certain' that the cat is dead or alive to meow in the first place?" (Heisenberg MAY have said that, but I'm not certain.)
@Doug Rosengard Cat speeds are "relative" if they came from the same parents.
We didn't pick the letter C for fun, you know 😂
@grovermatic C^2 is the area of the cross section of the cat in the direction of movement 😉
@cyborgdale do you not mean shrondinger?
I got so excited when I got the notification for this! I love Physics :)
Thank you so much for this video, i finally understand a lot more how relativity works while having light as a constant, and red-blue shifts in light make more sense, because the speed doesn't change, but if you imagine each point as a wavelength, then they get more spread out as they move away from you, or closer together, as they get closer.
3Blue1Brown - 2018-04-03
So good! The animations were well-chosen and super helpful, and the motivation for each successive step feels so natural, despite the fact that you built up to a famously unintuitive idea.
Sakib Abdullah - 2019-10-06
Whattttttt!!!!!!3Blue1Brown is commenting.....It's seemingly the best youtube channel on youtube for Maths.
William McAlpine - 2019-10-21
Is there a resource available to help me understand the equations for when I need to calculate stuff
Sheik das arabia - 2019-11-05
Seems like a crossover
John - 2020-01-15
You two do propaganda for each other?
RenneDanjoule - 2020-03-03
Einstein’s Special Theory of Relativity requires systems of clock-synchronized stationary observers and the Lorentz Transformation. Without both, the Theory of Relativity fails. A system of clock-synchronized stationary observers is, however, inconsistent with the Lorentz Transformation because it is Galilean. The Special Theory of Relativity insists that systems of Galilean observers must transform not by the Galilean Transformation, but by the non-Galilean Lorentz Transformation. The Theory of Relativity is, therefore, invalid due to an intrinsic logical contradiction.