I have been an astrophysicist in MIT since 1966 and have worked in the field of X-Ray astronomy. I am famous for my freshman and sophomore lecture courses in physics, now available online for free. They are watched by thousands of people everyday all over the world and are recognized for my inspiring demonstrations and their clarity. I can make difficult concepts simple.. I have also written the book "For the Love of Physics" which has been translated in 12 languages and is a bestseller in popular science. Two of my courses have also been offered as MOOCs and have been a huge success. For a brief promo, watch this video


Ask me Anything!

EDIT: I'm leaving now. Thanks for the questions!

Comments: 136 • Responses: 43  • Date: 

sonic_shock33 karma

Not a question, but I just wanted to thank you Walter Lewin. I dropped out of school when I was 13 and didn't know what I wanted to do with my life. But discovering your lectures and you infectious passion for teaching physics got me hooked and I started learning things I never thought I was able to, and thanks to MIT's Edx program I was able to continue that learning path into other subjects like chemistry and computer science. Now after many years of self-study I have finally been admitted to university for a degree in Physics later this year and I feel like I owe it all to you. So thank you, Walter Lewin.

WalterLewin16 karma

Thank you for your kind words

cookies5079626 karma

Hello Dr.Lewin, I have watched your physics lectures online and just wanted to thank you for teaching them with passion and love unlike some of my professors. Stupid question here: how long did it take you to master drawing a dotted line with chalk the way you do? Thanks!

WalterLewin29 karma

I can teach anyone how to do it in 2 minutes we need chalk and a blackboard.

deknegt11 karma

Which things (about anything) still blow your mind to this day?

ex. I understand completely how radio waves work, but how it all gets translated to something perfectly understandable is something that still blows my mind despite knowing the technicals.

WalterLewin24 karma

It surprises me that we can still live on Earth. We are polluting our drinking water and air. It's only a matter of time i guess.

The more you work with physics concepts, the more comfortable you will feel. However, there are many things in physics that you will never "understand" and they have been postulated. Newtons laws of motion have been postulated, they cannot be proven. Einstein's speed that cannot exceed c has been postulated, it cannot be proven. Yet it can be shown in thousands of different ways that that postulate is consistent with observations. THe same is true for Newton's Laws.

constructdistraction11 karma

Hello Professor!

What advice would you give someone in high school trying to get into physics and engineering?

I also just want to say, your lectures are legendary and I always watch them to review the topics being taught in my class.

WalterLewin20 karma

try to get admitted to the best University that would accept you and study Physics and Engineering

bamcrunchbolt6 karma

Firstly, thanks for helping me graduate with a respectable GPA -- and more importantly, helping me really grok intro physics.

I'm now a high school physics teacher, and I've noticed something really interesting and weird about my students. If they have a formula like y = mx, they're fine; if that formula becomes c = lambda*nu, they don't take it as well. So here's my question: In what ways can I help my students become comfortable with math in a physics-y context?

WalterLewin10 karma

PRACTICE - and give some easy examples in which you change the notation without changing the question. Students see then that "symbols" be it x, y, q, p, z or nu are ONLY names, but have no intrinsic meaning. Of course, we have certain conventions and they make things easier to remember. charge q, mass m, velocity v, speed of light c, temperature T, time t etc. Students will make them part of their culture through PRACTICE.

exscape6 karma

Hello, professor Lewin!
I'm hoping you recognize me from 8.01x and 8.02x. I enjoyed both of them immensely, so clearly my first question must be:

  • Has there been any more discussion about whether there will be an edX course for 8.03x: "Vibrations and Waves"?

  • Is there anything in particular that you're extra excited about in modern physics (in any field)?

Also, I just want to say thank you for all your work and your infectious enthusiasm for physics!

WalterLewin8 karma

no decisions have yet been made by MIT's Physics Department on putting 8.01x or 8.02x again on line and there are no plans yet to prepare an 8.03x version.

constructdistraction6 karma

Any life advice you would give?

WalterLewin43 karma

Depends on your personality and what your goals are. In general for all personalities: eat healthy food, do not smoke, no drugs, no abuse of alcohol, respect freedom of religion don't be so stupid to think that yours is the right one, support the poor; they were less fortunate in life than you. Charity is important. Educate as many people (not only your kids) as possible. Education widens people's horizons and enriches their lives. Education on a global scale will diminish the absurd hatred that exists between races and religions.

externals3 karma

Hi Professor Lewin! I am delighted that you are doing this AMA and that I woke up in time to catch it!

My question is:

What do you think will be the next big breakthrough in physics and how will it change the world?

I am a current undergrad looking to pursue a PhD in physics, and I hope to one day be a great a professor like you. Thank you for your many contributions to countless students everywhere! You're a great inspiration!

WalterLewin9 karma

I do not know - I have no x-tal ball vision

NatalyaSusulovska2 karma

Do you think there's any purpose of human existence?

WalterLewin11 karma

I do not believe there is any purpose to human life. But I respect people who think differently. It comes down to "believing" ("religion"). Anyone is allowed the freedom of "believing". However, I am strongly against countries where people are supposed to believe what is dictated by some governments (and dictators). In some countries you can even get murdered if you do not believe what you are "supposed" to believe.

NatalyaSusulovska-1 karma

Why do you think there's no purpose of existence? Is it possible to remain between rational uselessness of the humanity in terms of the Universe and intuitive search for the reason of being?

WalterLewin18 karma

Natalya arguing about "belief" is a waste of time. Arguments based on "belief" are irrational. You are entitled to belief so am I.

[deleted]1 karma


WalterLewin7 karma

Hello Natalya. I don't believe there is any purpose to human existence. However, I respect the opinion of many who think differently. It comes down to "believing" and I am in favor of the freedom of "believing" (reigion). However, I am strongly against countries where such freedom does not exist. To the extreme that you can be murdered if you do not "think" like you are "supposed" to think as dictated by some governments (and dictators).


Do you find yourself applying physics concepts to other disciplines (economics or psychology for example) or to your personal life (relationships and moral values)?

WalterLewin5 karma

Physics is a new way of seeeing

Read Chapter 15 of "For the Love of Physics"

deeplife2 karma

Professor Lewin, How do you manage to balance teaching and research? How do you manage not to see teaching as a chore? It seems like many professors only want to do research and see teaching as an obstacle in their way.

WalterLewin-1 karma

You will find the answer in my book "For the Love of Physics"

PhysicistInTheMaking2 karma

Dr.Lewin as summer is fast approaching, and it seems as i have not planned anything - i am in highschool- What do you suggest i do over the summer? Please excuse this question, if it is stupid.

WalterLewin8 karma

Read "For the Love of Physics", read it 5 times

Fa1l3r2 karma

Hello Professor Lewin,

I have a few questions:

  1. What or who has inspired you to teach physics and to research concepts in physics?

  2. Will you offer another MOOC course on edX or some other place?

  3. In your view, who, besides you, teaches physics in an engaging and helpful way? Are their lectures and materials also online?

  4. What do you think of the current state primary and secondary education for hard sciences like physics? For the U.S.A., what should change, if anything, or should K-12 teachers do something differently? In your opinion, what is the best nation, region, or city in the world that prepares pre-college students for college-level physics?

Thank you for your lectures and response. I have found your enthusiasm contagious.

WalterLewin7 karma

  1. teaching is in my blood (already when I was 15 yr old) no one in particular inspired me. As far as research is concerned, I was so very fortunate to become a 2-year postdoc at MIT within 4 years of the discovery of extra-solar X-ray Astronomy. I joined the pioneers and I became a Professor at MIT within 6 months. I stayed at MIT ever since. It's heaven for me. At MIT anything is possible if you have talent, ideas and energy.

WalterLewin5 karma

a contagious enthusiasm is a necessary (though not sufficient) condition to be an inspiring teacher.

WalterLewin4 karma

  1. google edX

  2. there are quite a view excellent Physics Teachers. You should search on line.

  3. "college-level physics" is not well defined. Google "the world's best Universities in Physics". That will tell you a lot. The US has a dozen centers of excellence. Europe has 2-3: Oxford, Univ of Cambridge, ETH (Zurich).

Shivanigrover2 karma

Hello professor Lewin I just can't thank you enough for making me see beyond the equations and helped me to grasp the key concepts from those wonderful lectures you are the best teacher ever :)

WalterLewin3 karma

thank you

SanshaSa2 karma

Hi Walter. I am here to say Thank you for all those amazing video lectures. Those helped me understand the hardest of the topics. You are Great and amazing!

WalterLewin4 karma

Thank you Sansha you too are amazing and you are so close to my heart.

Feynmanium1172 karma

Hello professor Lewin, huge fan, thank you for being a sort of pioneer for world class education to the masses. I was wondering what you think of The Khan Academy, and their physics programs? Have you ever thought of continuing more physics classes? Maybe work with an organization like Khan Academy? Lastly a question which I have been dying to know, you got your PHD in Nuclear physics, if you were an undergraduate right now, what field of physics would be studying, and getting a PHD in?

WalterLewin3 karma

I think the Khan Academy is great. I have 121 1hr lectures on the web. They two compliment each other.

I would not know which filed of Physics I would choose now if I were an undergraduate. Keep in mind that I did get my PhD in low-energy nuclear Physics, but switched within one year to a completely different and new field namely X-ray Astronomy in which I became a pioneer. That earned me my position at MIT (not my research in Nuclear Physics done prior to going to MIT).

Torann1 karma

My Dad took your edX course recently and he was delighted to have a great resource and still mentions your name regularly and with great respect. Just wanted to say thank you for what you do.

I suppose I should ask you a question. I'm doing a PhD in Electrical Engineering at the minute, but I'm considering leaving academia altogether once it's done, as I find the constant need for producing paper and defending your research emotionally trying. Was there ever a point in your youth where you considered changing your career path?

WalterLewin5 karma

I changed from Nuclear Physics to High-energy Astrophysics after I got my PhD.

misoporkramen1 karma


WalterLewin3 karma

I cannot tell as I do not know you

ebach1 karma

I recently watched this excellent video. What is your view of free will?

WalterLewin4 karma

too long for me to watch it now

itoowantone1 karma

I just moved to the Boston area. How can a late-middle-aged working guy best take advantage of physics resources at places here like MIT?

WalterLewin2 karma

I suggest you take MOOC courses.

CapAnson1 karma

One question I've always wondered about black holes and the event horizon.. if matter/energy/info can't ever leave a black hole once it crosses it.. could it be "pulled out" if a super massive black hole moved near a tinier one? That would seem to violate the principle, but I can't think logically why it wouldn't work.

WalterLewin5 karma

if two black holes merge the net result is one more massive black hole.

workingclassbum1 karma

Ok my knowledge of physics is pretty basic but I am a scifi nut. So if I can ask what may come across as a question from a simpleton by your standards given the issues of distance and time dilation do you think it will ever be possible for man to visit a star system other than our own and if so how do you beleive it would it most realistically be achieved?

WalterLewin3 karma

perhaps in hundred years but the first astronauts would not reach their goal because it may take hundreds of years to get there. Kids would have to be born on board to keep the mission going and the same would hold for a possible return to Earth

necrotica1 karma

As a man who in many circles can easily be called brilliant, what are your thoughts on Basic Income as a means to solve a lot of social issues in our modern developed world?

For Reference: http://danzynski.hubpages.com/hub/Basic-Income-Guaranteed-Minimum-Income

WalterLewin4 karma

The higher the GNP per person of a country the more resources will be available to solve social issues. This should be done e.g., in terms of FREE EDUCATION and FREE Medicare. However, this question can best be answered by a Politician.

Samahajan121 karma

Sir, when an accelerometer operates on the surface of or inside water, is it still in the same frame of reference as the on land or is any change in calibration required ?

WalterLewin4 karma

depends on the design of the accelerometer. One that is used in water will be different from one used in air.

skybrightthoughts1 karma

Professor Lewin, after taking a poor intro physics course at another prestigious university (supplemented by your video lectures), I'm curious as to what your philosophy is when it comes to teaching introductory courses where the students aren't necessarily going to become physicists and aren't necessarily interested in the material. How do you approach teaching 8.01 or 8.02, knowing this?

WalterLewin4 karma

Any broad-based academic, regardless of her/his specialty, should have some basic knowledge of Physics, Math, Chemistry, Math.

JaedanThandi1 karma

Top five books, you think everyone should read? Love your Work! and your dotted lines......

WalterLewin4 karma

that depends on your culture and background. Compare e.g., a Dutchman with someone in Tibet.

externals1 karma

Where or from whom did you learn to do the auto-dotted-line-strike?

I know how to do it, but I am wondering where you learned to do it.

WalterLewin4 karma

My math teacher in high school did them. He did not teach me how to do them as it is very easy.

SnazzyAzzy1 karma

Hi, I don't have much to say but thank you so much for your videos. I watched a bunch of them this past week and last night because I have an E &M final today.

WalterLewin5 karma

my pleasure

LewinFAn1 karma

Favourite physicist?

WalterLewin4 karma

I have not one favorite Physicist I have not one favorite visual artist either

externals1 karma

What field of physics excites you the most at this time?

WalterLewin6 karma


Jaedant1 karma

Top five books every physicist should read?

WalterLewin4 karma

Feynman's 3 text books For the Love of Physics (Lewin and Goldstein) translated in 12 languages The Privilege of Being a Physicist (Weisskopf)

Bleakfall1 karma

Hello Dr. Lewin, my question is have you ever used the website khanacademy.org? If so, what is your opinion of it?

WalterLewin5 karma


neogeogeek1 karma

Hello Professor, what do you think of the recent experiment to convert light to matter (http://www.ibtimes.com/scientists-discover-technique-turn-light-matter-1586166) and what potential studies could result from such research? Thank you for your work!

WalterLewin5 karma

I am not familiar with this article. However, the conversion of electromagnetic radiation into matter is nothing new. Google "pair formation".

qvulture1 karma

If I were a martian in my UFO a mile above MIT and I pressed my anti-gravity button, what would my UFO do/look like from an observer on the ground? No Change? Increase altitude? Go whizzing away?

WalterLewin4 karma

If you pushed your anti-gravity button then the person on Earth would see you moving along a straight line with constant speed (thus constant velocity) - Depending on the direction of the velocity the UFO may hit the Earth (with constant speed), or it may not hit the Earth, it may also stand still (speed zero).

Kayaksamir1 karma

Hi have you ever kayaked or canoed before?

WalterLewin3 karma

yes and yes

misoporkramen1 karma


WalterLewin5 karma

Admission criteria differ for the various universities. Most Universities have an "Admission" website. Take a look!

The_lawbreaker0 karma

I've allways wanted to become a physicist and I was wondering how much does one get paid?

WalterLewin2 karma

that varies a huge amount; it depends on the kind of job you will have and it depends on how good a physicist you are.

drkr39530 karma

Hello Professor! I want to ask that how an interesting subject like "Physics" should be taught? Whether it should be learned only by studying and reading books or actually doing it practically to understand the concepts better and in more efficient manner? or else do you have any other innovative method for it? I know there are many topics which cannot be done practical but can it be understood by connecting those topics with day to day life science?

WalterLewin4 karma

Where possible (and I try that in my lectures) I connect my teaching with daily experiences. There is NO ONE "best" way to teach. It depends on whom you are teaching. Key, however, is: What counts is NOT what you COVER but what you UNCOVER,

rustic_counter0 karma

Do physicists ever consider the social implications of some of their discoveries? Do they concern themselves with the state of the planet or question whether or not humans will make it to the next millennium? Next century?

WalterLewin5 karma

of course they do

think about the Manhattan Project