8.02x - Lect 35 - Doppler Effect, Big Bang, Cosmology
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- เผยแพร่เมื่อ 13 ก.พ. 2015
- Doppler Effect, Big Bang, Cosmology
Assignments Lecture 33, 34, 35, 36: freepdfhosting.com/33429fbcb9.pdf
Solutions Lecture 33, 34, 35, 36: freepdfhosting.com/1d839ac5ee.pdf
Optional Assignments Lecture 33, 34, 35, 36: freepdfhosting.com/b12020bee7.pdf
Optional Solutions Lecture 33, 34, 35, 36: freepdfhosting.com/de2e9ba7f2.pdf - วิทยาศาสตร์และเทคโนโลยี
This website contains all my 94 course lectures (8.01, 8.02 and 8.03) with improved resolution. They also include all my homework problem sets, my exams and the solutions. Also included are lecture notes and 143 short videos in which I discuss basic problems.
ENJOY!
I just found you today. I am honored to know that someone like you exists. Thank you for your work sir!
Thank you very much for the answer. I rewatched the lect and it is a bit clearer now :)
One more (begginer) question:
Can we generate a fake em wave not by using an oscilating charge, but by creating an oscilating magnetic field and also creating an oscillating electric field separately and overlap them? For example, if we take a solenoid and put it between the two electric plates. Then we apply apply AC current through the solenoid and AC voltage to the electric plates. We orient solenoid and plates so that the fields are perpendicular to each other and sync their phases so that we get something that looks like an EM wave.
Would we get something like a volumetric cylindrical EM wave instead of a plane wave, that would not travel but just be inside the solenoid? I wonder if we, in theory, use very high AC frequency in the visible light range, and if the plates and the solenoid are so big that the person can walk inside the solenoid, would the person be able to see the light inside? The light that does not travel...
where is link
The end brought a tear to my eye.
I'm 73 years old and sitting through 802, again!
super, I am 83 years old and sit next to you in the lecture hall 26-100.
This is awesome. I had 8.02 in 1970. Too bad that was before Prof. Lewin. I'm looking forward to 8.03 which I didn't take.
One thing common in every lecture of optics that Huygen is a Dutch! Hilarious! 🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣 Nice sense of humour professor!!!!
Walter Lewin is also an Dutch.
Dear Professor Walter Lewin, you're a major inspiration and a very wonderful person. It's such a privilege that in this age we can get to see your lectures on TH-cam. I've always wanted to attend your classes but unfortunately when you were teaching I was too young for school. Lots of love and best wishes.
amazing, in every lecture , I give to you a sound applause in my heart, thank you very much for sharing this lectures professor , kind regards from Honduras Central America
Wow, thank you!
Yay! Done with the course. It was a honor to sit in your class sir. No one can teach the way you do. You must be teaching teachers how to teach. I better start preparing for my finals :)
Thank you very much sir.
+sanath kumar Good luck with your finals!
thank you sir :)
Learning Astronomy in E&M course... What an AMAZING thing!! I think to find such a thing in another teacher's lecture is very hard. Thank you professor I've learned very important things in Astronomy
Amazing lecture with very deep and thought provoking parting words
just amazing 🤩🤩 thanks a lot sir Lewin for 8.02× and other videos which are so helpful to understand physics😊
Thank you Dr. Lewin.
:)
Hello Mr Walter Lewin, first I apologize for my bad english. it's because I'm french. And you know french people speaks often bad english.
But with your famous science lectures I understand you so well !! You're the best teacher I never had, really I'm fond of your lectures. So tahnk you very very very much for your sharing of your knowledge : it seems so easy to understand with you.
The last lines were extremely heart-touching sir !!! Today, I completed 8.02 and I seek your blessings to start with 8.03 sir.
Hello Sir, would you mind even uploading the video lectures on modern physics because I promise you that you will definitely get a 100k more subscribers.
Sir please try to upload them as it is not only my request but the request of 100 million students who gain immense knowledge by watching your extremely beautiful lectures.
Thank you
I am very curious to know about of cosmology .
Thanks professor
I remember a reference to flatland in Mathematics and the Imagination which is one of my favorites. I actually found a 14th edition which was from the late 50's, nice binding with gold aleph on the cover and for 2 or 3 dollars at the thrift store so its an awesome find there plus I think its signed by Bertrand Russell so pretty cool bonus though he didn't write it, he's only referenced in it.
I like the ending. Thank you, Sir.
Finally I have the technical details of redshift
at 22.15 the acid tests ! It has a whole other meaning for me...
I immediately think at the book, One flew over the cuckoo's nest written by Ken Kesey.
He started the gatherings in the Sixties calling... the acid test.
The house band was, the Grateful dead
dear Prof.Walter , i would like to know ur opinion for the current standard model of the atom and also for ur thoughts regarding the unified theory linking the general relativity and QM .
thanks in advance
It is a beautiful hypothetical conclusion you come to about the end of the universe and a carbon copy beginning again. Unfortunately, that is only the case in the universe where Kirchoff's loop rule always holds :)
Greetings from Ukraine. Thank you for the great lecture with a very promising ending - "meet you in a 100 billion years" :)
my ❤️ and thoughts are with Ukraine
@@lecturesbywalterlewin.they9259 So nice to hear that! Thank you for your support 🙏🏻
Congratulation for the 400,000 follower
thank you very much, I had not noticed.
excellent!
Thanks 👍👍
Dear Professor,1. What do we mean by the expansion of the Universe? What is expanding? I mean the current expansion rate of the Universe is 72km/sec/Mpc, which is equivalent to 72 picometer/year/meter.Does that mean, A one-meter long scale on the Earth, after one-year, will expand by 74 picometers? 2. Is expansion is uniform in all space? Or it also varies according to matter dominant curved space? I mean will the expansion rate same near the sun and one light-year away from the sun? (Assuming that there is no gravitational effect of any other massive object)
Use google. There have been important developments in the past 15 years. I gave this lecture in 2002.
Universe is expanding means the Space is Expanding not objects. Only space between objects is expanding.
professor you should also give your valuable lectures on modern physics and electronics to realise the beauty of physics
:)
Dr. Lewin, this is about 10:51 in the lecture. Due to the Doppler shift, the entire spectrum is supposed to shift to the blue or the red side right? So, how do we know if that particular line belongs to calcium at 3933.664 Angstroms?
>>> So, how do we know if that particular line belongs to calcium at 3933.664 Angstroms?>>>
There is 100 years of documentation about countless lines in spectra. Ratios are known to a high degree of accuracy. Intensities can also be used if needed. For more information use google.
Thank you sir.
thanks
Excellent lecture Sir. Thanks and Regards 🙏🙏🙏🙏🙏🙏🙏🙏🙏
Thanks for liking
What do you call the machine that is expanding the universe?
Professor , you said the velocity that is in the beta equation is the relative velocity then you said it is the radial velocity .Which one is correct ??
It's BOTH the radial velocity and the relative velocity between the receiver and the transmitter. It's meaningless to ask which of the 2 is moving; in SR only relative velocities have meaning. In my equation it's the radial component of the relative velocity.
Wahst happens when two objects near ligh speed approach Eachother. What about when they pass each other?
Sir, here at 7:27 you're telling the velocity to be radial velocity :) and if it is so then at perpendicular motion, you'll observe no doppler shift even due to time dilation. This is contradictory to what you said in the previous video on Doppler shift.
In relativistic doppler shift gamma*(1 - beta*cos(theta). If theta is 90 degree there is still gamma. This is called "transverse Doppler shift". This played a KEY role in understanding SS433. use google. click on "transverse Doppler shift" in wikipedia. Watch my lecture th-cam.com/video/313C1zo9pyE/w-d-xo.html
Thank you professor for this outstanding playlists..🌹
A question i wanna ask if there's any general relativity/cosmology lectures covered by MIT.
yes there are. Search MIT OCW; Prof Alan Guth
Found them, thank you prof.👍🏻
Sir big fan
hey walter - i have a question regarding relativity . i tried to find a lecture of you explaining about it with no success.
anyhow my question is mostly theoretical and is considering the laws of special relativity.
lets say we have a star that is about to collapse to itself and become a black hole . in addition lets say i travel in a spaceship towards that star in a speed close to the speed of light.
will i see the star as a black hole ? the reason im asking that is because of 2 things that happen thanks to relativity :
1. the length of the star shortens .
2. the relative mass of the star is greater
hence the relative density of the star is greater .
thx for any reply :)
the length of the star and its density does not change in its own reference frame.
www.scienceforums.net/topic/80055-does-the-density-or-the-volume-change-when-you-have-an-object-moving-near-c/
@@lecturesbywalterlewin.they9259 Thats right but in my frame of reference it does change. So do i see it like a black hole even though that in its own frame of reference it is still a star?
>>>So do i see it like a black hole even though that in its own frame of reference it is still a star?>>>
*that is not correct.* If you saw it as a bh you would not receive any radiation from it. Yet you will see the EM radiation from the star Dopplershited (relativistic Doppler shift) into very hi energy gamma rays.
@@lecturesbywalterlewin.they9259
Perfect! Thx! Im a big fan btw!
Hello, dear profesor Lewin your lectures are briliant, but this one about BigBang hypotesis is mostly based on beliving.
There are more and more evidence today that Earth has much more important place in Universe than it was beliving based on scientific dogma in 20th century. One example is "Axis of Evil".
The "Axis of Evil" is a name given to an anomaly in astronomical observations of the Cosmic Microwave Background (CMB). The anomaly appears to give the plane of the Solar System and hence the location of Earth a greater significance than might be expected by chance - a result which has been claimed to be evidence of a departure from the Copernican principle.
What is your opinion about this?
Professor Lewin... I've a question... May be it's kind of a dumb one.... sorry but.... If the sound source is going away from me with a speed equal to the speed of sound....I'm not clear how the sound wave reach me.... Would you clarify me Sir??
here is your answer
th-cam.com/video/tDC2UDhRGkA/w-d-xo.html
Thanks Professor...... Its clear now....... Grateful for the help... Respect & Love from India.... Wish I had a chance to have a teacher...a guide...a mentor... like you....in my student life... God bless you Sir....
Respected Sir, We know that every every electromagnetic radiation wavelength is fixed as in visible light violet and red have 400nm and 650nm respectively. But when we study wein's law there is peak wavelength which is inversely proportional to temperature of the body. How peak wavelength is different from EM radiation wavelength?? sir please help me
Peak wavel relate to black body radiation.
the universe is expanding with const. acceleration, so what is the reason for that acceleration i.e whats the origin behind that constant acceleration. is it the big bang which caused this
the acceleration is due to the *dark energy* ; it's not constant - use google
Sir I want to know more about dark energy and I already searched Google but IAM finding something missing when I try to find so please suggest what to do??
5:00 Its probably not the best idea to argue against a red-light-ticket with dopplershift. You may get a speeding ticket also. Unfortunally they are not for free in most cases.
What I do not understand is how can you say something is moving in de universe if you are on a rotating ball rotating around a sun which hurls trough space in a wobbling vortex way which rotates around a galaxy which in it self rotates with dust rings which rotates even counterwise.?
Use google!
What a way to CRUNCH THE LECTURE😅😂
i have heard from somewhere that law of conservation of energy does not obey in cosmological doppler shift of light my question is that wheather this statement is wrong or right
that is not correct - use google
Lectures by Walter Lewin. They will make you ♥ Physics. Thanks Dr lewin now i have right answer
Appreciate your work :)
so that model of expansion is only for that increasing red shift proportional to distance and for not to became the centre of the universe. I understand that expansion solves that problem well. but it is very strange idea to think over. But if acceleration is increasing last time period then it must be viewer for the far objects and higher for the nearer objects. If I read about gravitational red shift then it is to take in account, that we have to know how big is that star- A neutron star is compact and another star of the same mass but big diameter would produce less gravitational red shift. But also all sources do tell, that all formulas for gravitational red shift are not exact but some near approximated solutions. But then all data in astronomy are very risky to be wrong at all in very high range of failure. Sorry for my english.
en.wikipedia.org/wiki/Expansion_of_the_universe
What year are these from Walter?
2002
sir could you please give me a derivation of Doppler effect in sound waves
watch my lecture or use google
Can I have lecture's note please.
Doppler light effect... if light is sent over a distance of 1Billion light years to my eye, the universe is expanding, does that effect the frequency if you add additional space in between? After writing this I guess it wouldn’t.. hm or would it?
question is unclear
The light frequency as the light travels through the expanding universe does change. That is actually the reason of cosmological red shift, not the speed of the galaxies at the emission/reception of the light.
Hi professor I'd thank you to recommend the best book you know about Physics Cosmology.
Thank you Sir.
+Jordi GS Please search the web. Find one that will fit your present knowledge of math.
+Lectures by Walter Lewin. They will make you ♥ Physics. i dit it !! , but i want to know your opinion. I'm interested basically in concepts. My level of mathematics is not bad. I'm Nuclear Engineer. It's much better than my level of english language ... Please, serching in the web is always risky without a good advise. .
+Jordi GS Just tell me please wich is the best one for you from a conceptual point of view.
THANK YOU !!
+Jordi GS PS Your Lect 35 is magisterial. Thank you for make a poor nuclear engineer love Cosmology and Astrodynamics thaks to your 8.01 Lectures. I've purchased two amazing books (Vallado and Bate). Fantastic!!
+Jordi GS GREAT!!!
When it came to that giant balloon that was getting bigger as you were talking my fear of balloon went sky high I actually got so scared my heart rate went up I have globo phobia it put me off going into all sciences I don't like loud bangs either.😰😱
If the next big bang makes a carbon copy of this world. I will be watching Professor Lewin saving the Flatlander from their big crunch , again .
If we are in the center of the Universe and the explosion happened. Wouldn't the lights start with us and later fade away? So the light didnt travel to us. It traveled from us. Lets say in another 100 Billion Years we will see less stars in the sky. Im confused because I dont understand. How light will move away from us and not leave a trail and then later decide to travel back to us.
Professor, if two objects move in opposite directions with the speed c/2, does that mean for the first object the other is moving away with the speed of light?
Point of reference for speed c/2 can be a point somewhere between the two objects which is not moving w.r.t. objects.
Sir i meet u love of physics pls sir
So the reason why I, as a colourblind person, at distance dont see the red light, is why? 🤔🧐🙂
I bet you can make calculations in relation to this as well. 😉
Sir can you please do something good for Indian viewers. Can all these lectures be translated into an hindi audio voice?
does Doppler shift says that the color of the light we see in the sky of any star is not the actual color but shifted wavelength.....and actual color is calculated using the shift???
the blue light of the sky is due to Rayleigh scattering NOT Doppler shift.
Light from stars is Doppler shifted if there is a radial speed between us and the stars. If this speed is 30 km/s approaching, then the decrease in wavelength 0.01%.
thank u sir
sir to explain why earth and moon attracts each other but they do not come close is because space between them is increasing at the same rate of their approach...is this true if we consider only earth and moon as present in space and no other body
*No, this is NONSENSE*
watch my 8.01 lecture on Keplerian Orbits or use google
What is she doing 31.40
Great lecture but very unfortunate choice of cosmology as a source of a Doppler shift examples. Exoplanets discovery would be a much better example.
Doppler shift has changed our concept of the Universe in a way that nothing else has. Exoplanets have not changed our concept of the Universe.
I agree with exoplanet discovery not being important compared to expansion of the Universe. Moreover, even the first exoplanet discovery required redshift being calculated in general relativity framework while Hubble’s law is observable in special relativity assumptions. Hence, I take back my reservations about the choice of the example.
just realized this is from 2002 ...
Why do you like the Dutch so much?
Because he is Dutch ! :)
Halton Arp would disagree.
Sorry for the long comment. I saw this on a scientific forum and wondered if there's any truth to any of these four claims. I would be grateful if you could confirm any sir, in your free time
1) There's no black holes; they're a mathematical reification. All the simulation and models of them are conjecture yet perpetuated as if they were real. Again there's no direct empirical evidence for them, and it's only assumed that these mystical entities are responsible for cosmic structures, when well known electrical engineering principles can explain them all fully without invoking any imaginary nonsense.
2) All discussion on universe expanding and what ramifications that has are pure speculation, as the expansion model itself is based on elements like redshift signifying distance or speed (as a doppler effect), which are not empirically tested and proven.
3) There is no randomness in the universe, both field theory and the use or "erasers" in quantum mechanics prove it so. Logically, randomness makes no sense anyway, in a system that functions purely on direct interactions between fields. The "uncertainty principle" is a dangerous misunderstanding in QM in regards to the difficulty in measuring the effects of the atomic realm when approaching it from particle logic. The uncertainty principle is the issue where your observational tool interferes with the experiment itself - this was perpetuated via the double slit experiment, which is actually incorrectly reviewed. I, and many others have reproduced the laser experiments, to discover it can have the interference pattern with a single slit, or even around a sewing needle. When elaborating the experiment and using the erasers, you can bypass the supposed "neutralization of interference" which made people believe in particle-wave duality, and gain a result that's not only predictable, but measurable and has no randomness.
4)Laser light is coherent light, and known from holography art, that when split is can create a fractal effect in which every part of the image contains the whole image: this is called incommensurability. In quantum they call that entanglement, or spooky action at a distance where a split laser beam exhibits "entangled particles" that react to one another. The reality, they are coherent in of the same field; a laser is a light-resonant system.
1 2 and 3 is utter nonsense. It's written by crackpots with littler (or no) scientific education. I am not sure about 4.
I wish to be a physicist, I can’t believe you sacrificed your life in the United States, instead of being in the Netherlands. If I could study and pay attention I would do your line of work with attentiveness. right now I wonder in the forest in a truck camper seeking asylum from persecution for not being a normal American, I miss the Netherlands, or the peace your people gave me while I stayed in your country, I am running out of power, chaos theory is now and I hate it.