Lec 34 | 8.01 Physics I: Classical Mechanics, Fall 1999

[drumass666]

I typed in to YouTube search: "the world's a better place...the heat is losing"

I am pleasantly surprised.

[xtremetom180]

some sweet info here

[rodswebdesign]

good work here

[FlemmingKepler]

In Brazil we learn some of these equations on school.

[SuperNeutronX]

Top Teacher!

[Kricardose]

I am very happy to see the vidoe The Wonderful Quantum World Breakdown of Classical Mechanics after you give this

[bebeheuy]

I Love The Video The Wonderful Quantum World - Breakdown of Classical Mechanics It Can Increase My Knowledge

[Mjhond]

Steady I Really Like This Video The Wonderful Quantum World Breakdown of Classical Mechanics

[deyomash]

i have seen that the momentum has to be defined as momentum p devided by lorentz factor.

[MustangGTR2]

I will halt watching these series as quantum makes little sense to me.

[seadarie]

great lecture.

[Alternativemusic213]

THIS GUY HAS TO BRING ME TO BLACK MESA

[proaudiohd]

I wish every teacher were like this!

[iateyourgranny]

@kristijan0kroflin the uncertainty he talks about in the first lecture is an uncertainty in measurement: the accuracy of a scale is in millimetres, perhaps smaller for more precise instruments. but one eventually encounters a block, as one tries to measure both momentum and position more and more accurately, and this is heisenberg's uncertainty. it is an uncertainty in the very properties of the object itself, not merely in how we measure them

[MrAmaterasu96]

i am 15 years old .............. i understood this too somewhat extent! yay!

[Mrazmerize]

@kristijan0kroflin What I know is that you will get the same results because of the same conditions, and thus, "constant uncertainty". I think that's what he is trying to say.

[CuriousKirchhoff]

Professor Walter Lewin...forever !! :)

[J0tunhe1m]

Why can't all teachers be like him?

[Jipzorowns]

hwheahwehawehae he's dutch!:-D

[NLlBufu]

@Jipzorowns

Really?

Thats pretty awesome.

[superblub11]

Can someone explain me the answer to the question; ''If we're all vacuum, then why can't the other hand go threw a other hand?''

[EJNewbury]

@superblub11 I'm fairly certain it's due to electromagnetism. You can't phase through other objects because of the repulsions that take place.

[superblub11]

@EJNewbury Thank you very much sir =).

[punkistz]

@superblub11 as a beginner in physics, my bet would be on the electrostatic repulsion (culomb's law) between the electrons of the two atoms who are trying to pass through each other.

[x1x2x3ct]

not worth watching

[Mlpard]

Truly this proffesor is far better that all teachers I have ever had. hw is that kind of Teacher ... these do not need to deal with absence statistics because students are looking forward to the lecture anyway.

My adorations :)

[tanyaticphysics]

gr8 lectures sir. If interested in physics, visit tanyaticphysics.webs.com

[chaz3345]

dude this is colledge level material? Im a sophomore in high school and we know things far beyond this. He's awesome. Love his simplicity.

[RJonStreetz]

Al right seriously answer me. I am in 11th grade and I know this stuff ( in fact everyone in my class does ). So how is it possible that its being taught at MIT?

I live in India BTW. So is it that in US this stuff is taught atfer 12th??

[oshi1000]

@RJonStreetz but i bet u have not been taught with such insight & details along with historical experimentations & descriptions,(obviously, its india, and the pathetic education system)...

anyways, in this case, i think may be they do this 'revision' thingy, i guess for few or more months in the start...then get into serious higher physics later on... MIT level!!!! XD

BTW i am from delhi, and am just done with my 12th...(in PCM) ofcourse...

[animefreak619240]

doing high school physics makes this much easier c:

[Nabo00o]

27:28

So he says electron motion is explained by zero point energy...

Well at least its admitted it comes from somewhere.

[Nickah37]

Is het dutch? :p

[stamnion]

nice educator!

very good lecture!

but guys that's the 1st of 1,000,000

i got this lesson when i was 14 years old and 100% free...

is this MIT's level?

that's why NASA is full of greeks...! :)

[Luigi2533]

okay its settled im gonna do a physics degree :)

[Peekingduck]

great lecture

[mcslowlife]

who do professors look like nerds?

[jazzguitar2010]

@mcslowlife Because by your definition of "nerd," most of them probably are!

[wildcatone1]

wow i finally get why this happens, i read it in the book like 50 times and didnot understand it.

[spoconycygan1]

kurwa



[GelandnaleG]

THEWAVENATUREOFMATTER1:02

YELLOWSTARONRITEPOCKIT2:01

THEWAVENATUREOFMATTER1:02



[mdalikhoja777]

simply awesome ! but is there any practical way to teach all this to every student who want to be a future physicist ??????????

[lakeabaya]

God bless youtube

[xgamesterz]

those people dont know how good their lecturer is.. just listen to the applause

[reneemagray]

this man is amazing . He is our new Einstein

[eyeandi1]

well hughes, when you are a tenured professor of physics at MIT you can teach your class however you like. Until then, I'll go with Professor Lewin.

[hughesscotland]

His showing of a light/ photons performs through a small slit in a classroom was just so wrong. Funny thing is that not 1 person stopped him via the calculus or display and just asked how? why? I dont believe that.

Maybe you might ask next time?

Nobody knows it all. Old scottish saying "If you dont know, Just repeat what you learned"

[samuel91222]

@hughesscotland what exactly r u trying to achieve? what graviton? define the words u

[hughesscotland]

Dont they work out new theory and calculations with all the information they have available nowdays with advanced tech?

If you think about it the calculations they use are still the same. They were worked out in candle light without a calculator never mind all the things we have now.

Watching the video I did notice the "as this calc" as "that calc"

As you might tell I disagree with the end result of his lecture. No mension of graviton effect, Electron Di-displacement , or electron/vacuum.

[riflemaster]

What does the experiment tell ous?

Is it just that their is a randomness in the behaviour of quantum particles that we cannot predict. Or is their more. What is not so intuitive about this experiment?

[juansadaza]

WOW

[hrudy91]

that was incredible... that's all i can say

[Michaelas11]

its easy. i have a physics phd from mit. yes my name is gordon freeman

[6ZYX6]

HAHA go Freeman! love it

Seriously now... this man is just awsome.. such passion and energy to teach,.. this is a real educator!

[Xlaxsauce]

@Michaelas11

k genius. how fast does light travel away from itself

[riflemaster]

@Xlaxsauce 2c

[sarumanstrength]

Wow this sounds hard.

[freakywithfrogs]

LOL they done broke it down all the wayyy down..LOL LOLL done!

[kristiankroflin]

One question: how come that on one degree of the scale dimension there´s only the electron, proton and neutron and on lower and higher degrees there are particle zoos? Hint: with your monitor you have three extreme colors: RGB and by mixing different degrees of them you can produce 16,7 million "colours". So think about the trinity on the lower and higher degrees of the scale dimension - and if there´s really only the electron, proton and neutron...

[thehintsch]

if i understand your question correctly: there is not only the electron, proton, neutron, there are many more particles like the pion,kaon, myon... and all with their anti-particle. the fact that there are not millions of them like colours comes from the rules you have to put your quarks together to build a particle. for example number of quarks, combination of quark/antiquark and resulting spin of the particle.

[kristiankroflin]

That you did copy nicely. But where´s your own contribution? There´s no reason to give them all kinds of names. Complexity on the descriptive side - that you can do in engineering, not in physics. You chang the degree of the scale dimension (it gets more "microscopic") and then someone begins to invent names and others copy this blindly.

What´s the particle for the antiparticle? It´s the antiparticle for the antiparticle.

[thehintsch]

AND btw if you really had only 3 basic colours your can not produce more than 7 mixed colours ^^ remember that every color has 256 different intensities...

[kristiankroflin]

"for example number of quarks, combination of quark/antiquark and resulting spin of the particle. "

The same rules for how to set up an atom, only on a larger degree of the scale dimension - and only other names. But the name doesn´t change nature by itself.

[kristiankroflin]

The problem is that he doesn´t add up all the electrons with their circular velocities which are the baseball observed on a lower degree of the scale dimension. So you have the masses and the velocities of the electrons of the baseball....

[kristiankroflin]

"Returning to my baseball, take a mass of the baseball of, say, half a kilogram and give it a speed of 100 miles per hour.

Calculate the wavelength that you would find, according to quantum mechanics.

That wavelength is so absurdly small, it is 20 orders of magnitude smaller than the radius of an electron, so it is completely meaningless.

So quantum mechanics plays no role in our macroscopic world of pots and pans and baseballs.

But now take an electron."

[Theroen]

Isn't the Uncertainty Principle ΔxΔp≥ħ/2

[cleocool]

lolol at 2:35

[JayDaddie]

cleocool; thinking of a sucking joke?

[makedonas86]

sin 90 = 1

[luberies]

¡Qué profesor tan excelente y qué alumnos tan fríos, tan poco humanos, ni siquiera apludieron al profesor después de semejante conferencia!

¿Serán así cuando apliquen sus teorías en el futuro? No me gustaría que la vida sobre el planeta dependiera de uno de esos experimentos.

[ThjeshtLife]

he makes it enough interesting even if it's not my jubject

[RottenBrains71]

how ignorant of you in a physics lecture page, yes mexicans can understand this and probably better than you in some cases, I'm mexican.

[McCaler]

My Goodness!!! Do I ever wish right now that I was a child prodigy.

[smeerwrst]

serious

48 minutes

i felth asleep

he can't talk English he dutch guy.

[thepeach69]

That was seriously cool! I want more!

[GeoVerbose]

700-800 SAT

4 GPA

Work.

[BackyardSkunkworks]

And luck...

I had all three and didn't get in.

[greenhawk85]

good stuff mass velocity physical existence human understanding of light and magnetism .

[0polymer0]

I watched the first 11 minutes, is physics in general basically this simple to comprehend? I've been exposed to a lot of what hes talked about already(going to college next year). Which surprised me.

[gimplar]

Yes it generally is this simple. Physics I is all about taking big problems, decomposing them and then solving using the basic principles and equations taught. Most students don't have a problem memorizing these formulas, most have problems applying these equations to more complex problems.

Physics 1 = If you like puzzles this course will be fun. The problems are neat, compact and make assumptions that really simplify everything. This course really is a test of your analytical ability.

[nocciola123456789]

@0polymer0

I´ve just started to study physics, and it ist in fact easy to understand (even if some things are really, really non intuitive...!!) if explained and seen....

the problem is using physics, see the connections between the things, between something and his mathematical expression.

and even mor difficult is find new theories, as nobody explaines you!

but studying physics it´s the best choice i´ve made in my life, and i think you´ll get an idea of that looking how excited walter is!!

[privatekept]

What happened to Lecture 35? It was there before and now it's vanished into the ether.

[satriani20gc]

yeah it looks like that video is private... :S

[munoz1205]

Wow this professor is a great teacher

[ericcartman888]

Great!!! What is the professor's name?

[mremile72]

Walter Lewin =D

[ericcartman888]

thanx

[jreb01]

This really clarifies what i did in high school. My teacher never explained the concepts, she only gave out the formulas and a few examples so i was a bit confused.

[OgreTaskMaster]

Take a look at the photoelectric effect. When you shine light on a metal, electrons are emited. The wave model says that the energy associated with light is proportional to its intensity (amplitude) squared. What happens in experiment is a bit odd, and in fact does not support the wave model of light. Instead, the energy of light is proportional to its frequency. (E=hf, ~8:00 in) It is a bit more complicated, having to do with kinetic energy of the electrons, but wave model cannot explain this.

[Gicior]

I don't like the laser demonstration, it seems it can be explained by the much simpler wave model of light. Does there exist an experiment that can only be explained by Heisenberg's uncertainty principle?

Also I have a very hard time trying to understand light as a particle. Are there any experiments which definately prove the particle model of light, and cannot possibly be explained by the wave model of light?

[OgreTaskMaster]

Read about the photoelectric effect. It is the most clear cut example of particle properties of light. Roughly speaking, the energy associated with waves should be proportional to the square of the intensity (amplitude). However, experiments show that light carries energy proportional to its frequency (E=hv, ~8:00 in). Changing the intensity of the light does not change the number of electrons emited by the metal. The wave model fails here.

[Gicior]

Yep, you've convinced me. This explains it perfectly. Thanks.

[Adrianrff]

You got something wrong, when you change the intensity of the light, you DO change the number of electrons emited, what doesn't change is the kinetic energy gain by those electrons, since the energy quantum is the same (hv) but if you increase the intensity you send more energy quantums so more electrones will be stripped off the atoms but all with the same energy

[ganges333]

no adrianrff..when u increase the intensity,he emans that the frequency of the light is increased but the rays are kept the same.

so,when the intensity is increased,the no of electrong emitted is the same but they come out with different kinetic energies.

(its a prob with the term used there,intensity,its used in a wrong way.i was scratching my head too.but i figured it out later.)

[Adrianrff]

You are right, it is a prob. with the term "intensity", though it could be ambigious. In physics, intensity is defined as energy flux averaged in time, and has units of Power/Area ([Watts/sec.] in I.S.). So, consider a beam of EM waves that increases the number of photons emitted but with the same frecuency, according to that definition, it would have a higher intensity, and also a beam of EM magnetic waves that increases its frecuency but not the Nº of e emitted would have a higher Intensity..

[Adrianrff]

.. also, since the energy flux is increasing in both cases. Its clear for me that what increases the kinetic energy of the electrons is the frecuency of the Em wave, and not the number of photons. I might be wrong in what a stated before, but i think is a logical conclusion. You tell me. Excuse my sloppy english btw

[Adrianrff]

I just found this in the article of PHOTELECTRIC EFFECT in Wikipedia: "Increasing the intensity of the light beam increases the number of photons in the light beam, and thus increases the NUMBER OF ELECTRONS EMITTED, but DOES NOT increase the energy that each electron possesses. Thus the energy of the emitted electrons DOES NOT DEPEND on the INTENSITY of the incoming light, but only on the energy of the individual photons." This only confirms what already knew. The ambiguity of the term remains

[Bethreze]

Then, you mean that in the visible light range, the more intense light is, the more red will be it??

[ekid2k]

If I aim two flashlights at the same spot, I get light that's brighter than if I only aimed one flashlight.

That's what he means, it's getting darker.

[OgreTaskMaster]

Take a look at the photoelectric effect, for which Einstein won his Noble Prize for his work in. When you shine light on a metal it has been found that electrons are emited. The wave model would say that the energy should be proportional to the square of the amplitude of the waves. But what happens is that there is no correlation between the electrons emited and intensity, but instead the frequency of the light determines the energy of the light. The wave model fails here.

[jonahansen]

The easiest way to see it is to just lower the intensity of light progressively, and use a sensitive detector, like a photomultiplier. Eventually you get to a point where you are getting separate pulses or clicks out of the detector. Can't explain this with waves.

[kmckoy13]

I wish I had clear english speaking professors like this for my physics classes

[ken62310]

my teacher speak perfect good too..

but he never knows how to explain....