Monday, April 21, 2008

The full address for the Stanford Continuing Studies Modern Physics
Courses is

http://www.learnoutloud.com/Catalog/
Science/Physics/Modern-Theoretical-Physics/23022

LS

288 comments:

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Mahbub Alam said...

Prof Susskind,
I see string theory predicts scattering amplitude. Isnt it possbile to test these predictions in scattering experiments? Or other theories have these same predictions, so we cannot be sure?
Thank you
Mahbub

Polish Warper said...

http://www.theresonanceproject.org/pdf/torque_paper.pdf

Polish Warper said...

http://theresonanceproject.org/pdf/quaternions_spinors_twistors_paper.pdf

Did Haramein discover Unified Field Theory?

Vaibhav Khamgaonkar said...

Respected Sir,

I am Vaibhav,Engineering graduate in Electronics from Mumbai(India). I have very much interest in Physics & i am learning physics from your lectures.

I have some queries regarding Big bang & Black hole..
Sir, As we all know that Black holes have extremely dense matter situated on a single point & we know that all the laws of physics ends on black hole but sir is it correct since E = M * c^2 still holds on it(sir please correct me if i am wrong).

And another question is, Sir do we really think that before the big bang nothing was there? i am asking this question because i have searched a lot for this & i didn't get any solution which could satisfy me. Sir, I had a dream few days ago where i have seen that Explosion of a Black Hole(super massive black hole) is nothing but a Big bang since every thing is located at single point.(All the forces are located on a single point)
another thing is that which i saw, radius of the super massive black hole is very very large so that the event horizon is not visible from the center then this situation becomes exactly similar to that of big bang (where there is no event horizon or it would have been very very far from its center) but sir if we zoom out this drastically we may see the event horizon where matter could be available which means Space & time may available or we can say that our universe still exist before big bang.
and after the big bang it would have gone away from its original position.

Sir,Can this be possible which i am thinking?

pedro juan said...

Dear Professor,

Please add a Lecture concerning to Tensors and its applications.

PJ

pedro juan said...

Dear Professor,

Please add a Lecture concerning to Tensors and its applications.

PJ

Jose Limérez said...

Dear Professor: In your lecture of special relativity, I can understand the concept of Proper time, but not its mathematical expression.
It seems to me that dt2-dx2 is just an arbitrary definition, not coming from a mathematical deduction and that it has been selected only because it is invariant under Loretz transformations. So, as a crazy idea for my clarification, why not using ds, that is also invariant, or any other, to define the proper time.
Thaks for your great help. Jose Manuel-Spain.

Darsh Kodwani said...

In the 1st and 2nd lecture of quantum mechanics this year, the number of dimensions in a vector space was defined as the number of mutually orthogonal vectors that can be found. However does this principle not break down in a one dimensional space (how would you have something orthogonal to a vector in a one dimensional space, other than a numerical multiple, which was said not to classed as orthogonal)?

moises bessalle said...

Dear Dr.Susskind; On your first lecture about special relativity you assume that light travels at the speed "c" in any inertial reference system, but WHY does that happen? WHY does light in vacuum travel at "c" no matter what the velocity of the observer? I imagine it has something to do with space-time being pseudo-euclidean and not euclidean but I still can't associate the math with physical reality. Hope you can answer me. Thank you

moises bessalle said...

Dear Dr.Susskind; On your first lecture about special relativity you assume that light travels at the speed "c" in any inertial reference system, but WHY does that happen? WHY does light in vacuum travel at "c" no matter what the velocity of the observer? I imagine it has something to do with space-time being pseudo-euclidean and not euclidean but I still can't associate the math with physical reality. Hope you can answer me. Thank you

Deniz Yuret said...

Prof Susskind,

I have watched the first two lectures in the quantum theory course. It seems to me that the spin experiments as described so far are compatible with the following scenario:

1. Each electron spin really points in some random direction in 3-space.

2. The measuring device only reports the sign of the cosine between the spin and the device axis.

3. Each measurement disturbs the spin in a random direction compatible with the measurement result, e.g. if we measure sigma_z = +1, the spin angle is reoriented to a random unit vector with a positive z component.

With this as our "model" we can derive every probability you describe with a bit of trigonometry. There is no quantum weirdness going on here (so far). Why are we going to extraordinary measures of overthrowing regular logic, getting complex numbers into the picture etc.? Are there simple examples that clearly demonstrate the need for such a representation?

best,
deniz

Gerry said...
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Gerry said...
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Gerry said...
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Gerry said...

I have a question about invariants (scalars). I shall use X^m for X upper index m and X#m for the lower index. Prof Susskind stated in lecture 3 of Special Relativity that if A^m and B^m are 4-vectors then A^m.B#m is invariant.
The difference between B^m and B#m is in the sign of the time component. However the sign of the time component in B^m seems to be arbitrary, so we could put C^m=B#m component by component and C is a 4-vector. In that case A^m.C#m is invariant. But this is just the same as A^m.B^m. This suggests that all such products are invariant which didn't seem to be what was intended. Is there a fault in this reasoning?

Claudio Arena said...

Dear Dr. Susskind,
I've recently read your book "the black hole war", and really liked it. I tried to understand as much as I could, but I still have one doubt. You talk about conservation of information as something that need to be maintained, and I hope to be right in saying the book is actually about this. So my question is, for neutral kaons and neutral B-mesons decays, where time reversal is not respected, is information conserved? If yes, how? and if not, wouldn't that be a problem? Thanks!

Rajguru said...

Dear and Respected Prof. Susskind
Wishing you a happy new year.............
I am a physics student from India following your video lectures on internet. Sir I have a problem about the electric field lines. I wanna know whether the electric field lines form close loop in any situation like a non conservative fields (electric field produced by a changing magnetic field). Because electric field produced in a close loop (by a changing magnetic flux) is always in the same direction around the loop so does the notion of electric field lines work in for non conservative situation also...........
Thank you sir

Toad Frog said...
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Benjamin Williams said...

I have a question regarding a thought experiment of mine:

Suppose you are in a space suit, and are falling into a very large black hole with miniscule spagettification effects. According to the equivalence principle, you should not notice when you have passed the event horizon. Everything above you looks pretty normal (sped up and blue shifted, but otherwise normal) and below you there is just a black void, since you must see the same thing when you are inside a black hole as when you are outside.

Let's say you fall feet first. After you pass the event horizon, everything below you is part of the black void, since light and information cannot reach you. That means that you cannot see your feet, and no information can be passed from your feet to your brain, so you have no feet. Your chest cannot send blood up to your brain, so you have no heart. The lower half of your eyes cannot communicate with the upper half of your eye balls, so you have no eyes. You were alive and functioning when outside a black hole, but the upper parts of your body lose any physical interaction with the lower parts. If we start this experiment outside the black hole, your feet are the first to pass the event horizon, and so you lose all connections with your feet, and any parts that pass the horizon before your head. It is rather painfully obvious that you are passing the event horizon.

This seems to be at odds with the idea that nothing can tell it's passed the event horizon.

Let's assume that there really has to be no way of detecting when you pass the event horizon. This requires that information can be transmitted upwards, for at least a small distance, from a black hole. To see the consequences of these assumptions, let's have two particles on opposite sides of the event horizon, within a millimeter of each other. The inner particle emits a photon towards the outer particle. According to the emitting particle, the photon leaves at the speed of light. This means that the light has some component of velocity as it travels upwards. However, since light can be transformed into mass, and that possible mass is traveling away from the singularity, the total energy of that photon must decrease, which means that the wavelength increases. Let's say that the acceleration of the black hole at the event horizon is about 1G. It's hard to believe that the photon is unable to travel the 2 cm between the emitting and receiving particles because of that small distance. If that's the case, then black holes are not really black, but a dark red, with objects nearer the horizon being brighter and less red that objects deeper in the black hole.

Both results seem ridiculous and the governing principles, which individually are laws and are compatible here in the rest of the universe, are contrary at the event horizon.

Where have I gone wrong?

jamie savage said...

Hello, you have been a great teacher to me from afar. My concern involves the motion of a body. What is motion at the quantum level? I have put considerable thought (an unusual amount) into this question, and my conclusion contradicts Special Relativity. I keep rethinking and questioning myself, but I always end up at the same result. The general hypothesis is: The motion of a body entails a contraction to the length of space relative to the body in the direction of motion, with a corresponding expansion to the length of space relative to the body opposite the direction of motion. Could this be true? Most people I explain this to think I'm a crackpot, I just blame it on my ADD. I have a six page document, and publication is pending.

Thanks for everything.

Jamie P. Savage

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Thales said...

I would like to thank Professor Susskind for his work, that is worth so much for so many people that are trying to learn physics. I understand that he is not answering the questions on the blog anymore, of course, there are so many questions for one person to answer. But I have an unresolved question about a type of "delayed choice quantum eraser" experiment, and I would like to address it specifically to Prof. Susskind, as I have already asked everybody else and they still haven't solved the question. I'm not gonna describe it here as it would take too long for the chance that there is of him answering it, but I will leave my e-mail in the hope that he will contact me, in case he is interested in knowing more about it. Thanks. My e-mail: thalespo@gmail.com

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John Smith said...

Part one

Professor Susskind

I would sincerely like to thank you and everyone else involved in providing free lectures online. I never had the chance to attend university as I left school at the age of 16. I have mild dyslexia which made school a challenge and it was just easier to get a job.

Now this may sound far fetched but from watching your lectures I think I may have worked out a theory of gravity which also explains dark matter and dark energy and does away with zeros.

It involves combining Einstein's special (not general) relativity and Newtons teachings on gravity, in particular the stuff to do with escape velocity

The basis of my thinking is that the concept of gravitational 'acceleration' is flawed and should be replaced with a similar concept that is based on a constant velocity instead, which special relativity is then applied

What I mean by that is

If it's possible for mass at rest to behave in space like it is accelerating in all directions without moving, then, why not in the same kind of way say mass has a constant velocity in all directions without moving, this velocity being related somehow to the same laws that determine the escape velocity of something with mass i.e it changes depending on the distance from the centre of mass as per Newtons teachings.

This would give two measures of velocity that special relativity can then be applied to

Here is an example

Imagine a car that is parked and there is a person standing next to that car, in that car there are two speedometers

There's the normal one which is reading zero, lets call this the 'standard velocity'

The another one is reading 11.2 km/s (at least on the surface of the earth it does) lets call this 'zero distance velocity'

Despite the car not moving relative to the stationary observer who is standing next to the car, I believe it should be calculated as if it were, I don't know if this would be 11.2 km/s or 22.4 km/s (11.2 km/s for both the stationary car and stationary observer) or some function of those values

By applying special relativity to this value we increase the cars weight above what it would be if it were for some odd reason floating out in space far away from any other source of mass

This extra observed weight could be interpreted as dark matter

WR VandenBos

John Smith said...

Part two

In another example lets think of an expanding sphere of gas that contains a given amount of matter and has a given amount of expansion energy.

As the gas expands and its radius increases the escape velocity on the surface of the gas sphere will decrease (as per Newtons teachings) and if we apply special relativity to this value (the 'zero distance velocity') as well as the 'standard velocity' we would find that the matter on the outer surface would behave as though it was decreasing in mass as the sphere of gas was expanding, it would also appear to accelerate as the 'zero distance velocity' and its associated relativistic value decreased

This extra velocity could be interpreted as dark energy

This gives a mechanism in which an apparent mass to energy conversion can take place in which the said dark matter will convert into the said dark energy when matter expands into space, this would be most noticeable on large scales simply because being a function of the escape velocity the amount of matter it takes to build up a high enough 'zero distance velocity' would need to be large to become noticeably relativistic

This would be a positive feedback self reinforcing system, in some cases that would cause oscillations between apparent dark matter and apparent dark energy, I believe that this could be responsible for the spiral arms in galaxies by creating 'gravity hills' in between the arms with the peak of the hill being the lagrange point, on one side of the gravity hill mass would behave like it has dark matter and on the other side of the hill mass would behave like it had dark energy effectively creating band gaps, this suggests that on large scales gravity is quantitative

Lastly if we think of mass as being able to behave like it's moving without needing to move, we can explain the apparent g-force felt when standing on the ground as being a function of continues constant 'zero distance velocity' as opposed to a type of acceleration

I believe this is due to the geometry of the space that mass exists in causing an imbalance in the otherwise omnidirectional 'zero distance velocity'.

This is evident in the fact that my feet have a slightly higher 'zero distance velocity' than my head rather than moving evenly in all directions, this imbalance in my 'zero distance velocity' is pushing me in a direction toward the centre of mass, kind of like a continuous impulse force or even a type of zero distance continuous free fall

One of the significant fundamentals of my idea is the fact there is no zero velocity even when dealing with mass at rest relative to an observer

Mass at rest behaves as though it's moving relative to itself

This makes a lot of sense in an expanding Universe with no centre

I mean if there can't be one centre to the universe, why would there be lots of them?

WR VandenBos

John Smith said...

I have a unified theory as well, but I'm still working on that one

John Smith said...

Part three

Ultimately what I'm suggesting is that two objects with mass will behave as if they get heaver or lighter depending on their distance from each other

I'll try to crunch some real numbers once I figure out how

I know there is linear velocity (standard velocity) I'll call that V1 and I'll call the 'zero distance velocity' V2. I'll also make another unit Vt or total velocity where Vt=V1+V2

Vt in my minds eye should equal to the velocity that Issac Newton would have calculated i.e non-relativistic

V1 would be equal to the velocity That Albert Einstein wold have calculated under special relativity

V2 would be a counterintuitive velocity that is in someway related to the same laws of space that govern the escape velocity and itself would be subject to special relativity

It should be noted that because V2 is omni-directional (putting aside any imbalance that manifests itself as the force of gravity)this means an objects V2 relative to an observer would both red shift and blue shift at the same time because it's behaving like it's moving in all directions with respect to its V1

WR VandenBos

John Smith said...

The secrete sauce in this recipe is transforming the escape velocity into the equivalent V2 in order to do the relativistic calculations, at this point time I'm assuming escape velocity (based on luminous matter) squared will give the correct V2.

Preliminary calculations do show promise

However I need to do more research and fact finding

Alex Postevca said...

Professor Susskind, i have one question about the basics of theory of relativity, and mainly the time dilatation and length contraction, i think we all know the thought experiment with a light clock, a beam bouncing between 2 mirrors, i understood this example, but in my mind i feel that something is wrong there... i will spare you from my arguments right now because i am not sure if i'm right or not, and that is what i want to find out, instead i would want to know what happens if we repeat this experiment, but with the clocks rotated by 90 degrees so that the beam will travel parallel (and not perpendicular) to the clock's vector of movement, i want to know how the beam will be observed from both moving and stationary points of view and how time dilatation and length contraction apply there? i would really appreciate if you could give me the answers which my brain so desperately seeks, thank you in advance and have a nice day!

Terrance Toner said...

Dr. Susskind, just a note to thank you for this blog and your popular books, I'm presntly reading "Landscape" and "BHW", so obviously I'm no physicist. Your books have, however re-kindled my interest in physics and I've begun to review my calculus, stats, etc. Amazing how much a person can forget in 55 years, (I'm vintage 1939). Even my calculus book is ancient, though not autographed by Leibniz, its first publication was in 1897!
Again, thanks.
John Toner

Valentin Manolov said...

If gravitons exist,how do they escape the event hrizon of Your blackhole?

Valentin Manolov said...

i have observed boiling water memorising sounds.And amplify them.If it's due to hidrogene,the Sun mlght be a greate computer,or a creative mind.

bijan shariat said...

DEAR PROFFESSOR SUSSKIND:
MY NAME IS BIJAN AND AM 53 YEARS OLD. I AM CURRENTLY WORKING AS SCIENCE AND MATH TEACHER AT INGLEWOOD U S D. I GRADUATEDDO HAVE SOME DISABILITY CALLED MS( multiple sclerosis). I GRADUATED FROM CAL STATE UNIV NORTHRIDGE IN 1997 WITH MASTER IN PHYSICS. I AM FASINATED BY YOUR LECTURES ON YOUTUBE. I DO LEARN A GREAT DEAL FROM YOU. ONE THING THAT BAFFLES ME IS YOUR LACK OF BELIEF IN ALMIGHTY GOD. YOU ARE TEACHING US HOW COPLICATED AND PERFECTLY DESIGNED THIS UNIVERSE IS. NOW, IS THERE ANY DOUBTS IN THE PRESENCE OF GOD THE CREATOR OF THIS UNIVERSE? BRING YOUR REASONNINGS, IF THERE ARE ANY.
PLEASE DO NOT LISTEN TO ALL THESE NON SENSES THAT SO CALLED RELIGIOUS LEADERS SAY. USE YOUR OWN BRAIN, BECAUSE AT THE END OF THE DAY YOU ARE RESPONSIBLE FOR YOUR OWN THOUGHTS AND ACTS. I’LL BE GLAD TO ANSWER ANY QUESTIONS THAT YOU MIGHT HAVE IN THIS REGARD.

SINCERELY, BIJAN.

AneikwSeMena said...

Dear Sir,
I'm facinated too by your lectures. They are really great. Well i have a questionand i go right to the point.
How does the second law of thermodynamics (entropy always increases) come into pieces with the law of conservation of energy?
Siencerly
Konstantinos Georgiou

AneikwSeMena said...

What i mean is that everything falls appart if entropy always increases. F=ma is no longer applicable cause you should take into considaration the effects due to entropy as well. E=Mc*c+/- entropy. All the known equations should take into considaration entropy. And how can someone see dissorder in such an orderly universe? Take the solar system... orbiting the galaxy. Then the planets orbiting the sun, then the atom and the electrons orbiting aroun the nucleous.
I've seen a couple of examples trying to explain entropy. The example with the atoms around the walls of a sealed container then you let them go and imagine what will be the result. Yes they will uniforly fill the space of the container but only because these are vibrating. And if they are vibrating the Energy is not 0. If it was zero? Would you have any dissorder?
And can you have any disorder without energy increase? Can you brake a ceramic without the use of energy? No heat to brake the bond or no throwing against the wall?
Sincierly
Konstantinos Georgiou

Miguel Gonzales said...

Hello, I'd like to know the resonant frequencies of the planets in our solar system. Thanks

John Smith said...

Happy new year physics, 'If' it is true that the V2 is the square of the escape velocity that would suggest that a galaxy with an escape velocity of approximately 548 km/s (the square root of C) would have an infinitely high V2 Lorentz factor, This applies only to its V2. Its V1 would have a low Lorentz factor, I'm going to need to scratch my head for a bit and figure out what is subject to V1 and what is subject to V2. Obviously light would be V1 as would be 'some' of the motion. I guess the stuff that can move faster than normal would be V1 and the stuff that's not moving as much as it should would be V2 That's the tricky bit.

WR VandenBos

Jose Severiano Lopes de Queiroz Neto said...

Dr. Susskind I have a small question to place to you. For some years I have been conjecturing about the possibility that for each Black Hole we may have its counterpart a Worm Hole. What is your oppinion ?
I am doing an work that points to this relation.

Jose Severiano Lopes de Queiroz Neto said...

Dear Leonard Susskind

For some years ago I have been thinking that we can´t think about a Black Hole without thinking about its counterpart a Worm Hole. For me they are strongly associated.
I have arrived to this conclusion due to a work on these entities.
What do you have to tell me about this ?

Sincerely

Severiano

Ole Stilling said...

Calculating trajectories in special relativity, I have a smal problem with initial conditions where the particle is at rest. It does not start to move as the experience is when releasing an apple in mid air.

something seems missing.

Samik Sarkar said...

Dear Professor,

I have two queries regarding the basic postulates of Quantum Mechanics

1) As per Uncertainty Principle, position & momentun of a particle can never be measured precisely & simultaneously. Is this principle signify HUMAN's unability of measuring precisely & simultanously.

2) Why wave function is probabilistic not deterministic

Regards,

Samik Sarkar

John Smith said...

I'm working on using better terminology than what I've been using previously and I'll try to tie my previous thoughts together into one future post. From here on out I'll call V1 'Velocity' and V2 'Gravitational velocity' with Gravitational velocity being the equivalent of velocity in the same way gravitational acceleration is the equivalent of acceleration. I would also like to add that gravitational velocity is rotationally invariant in terms of position about its centre of mass. I'm also going to need to start chiming in with my unified theory to explain the square to square root relationship and the general geometry of the two types of space we live in, so there might be a few more ramblings to come before I can pull these thoughts together

WR VandenBos

debroek said...

Dear sir, i like to say that having watched your unprepared lecture on blackholes and hologram have given given me hope to be able to share something i have found,you spoke of B and A and their entanglement. The question is we can check the info of B but not ofA i think that i have solved part of that problem .through a series of what seemed coincidences i discovered a pattern. This pattern revealed that the measurable universe and its laws are a logically flowing from A, but due to having shared some of it previously and having been taken as their own i do not wish to share it publicly at this point as some have been taken by some popular lecturers as their own so if interested please mail me personaly so i may share it. Moshiya888@hotmail.com

Franz said...
This comment has been removed by the author.
Franz said...

Could dark matter be for gravity what a magnet is for e-m. ? I mean, a charge in motion generates a magnetic field which interacts with other charged particles in motion. What about a mass in motion? Does it also create a secondary field other than gravity which affects other massive particles in the nearby? (I used the analogy with magnetic fields and found out that it should have units of 1/s, such as the Hubble parameter). If so, nature itself created the magnet (Ferrite), could it be that dark matter is the "gravitational" magnet? If such thing would exits I think it should be literally invisible and it would have the effect of "gravity" for objects in motion, not for static ones.

Volker Diesel said...

Dear Mr. Susskind.
First of all thanks a lot for giving these lectures. I've watched a lot them and it's been real fun!
I have a question that puzzles me since years. I hope it's physical enough and not too philosophical.
It's about quantum mechanics and it's about what exactly the reason is, why a quantum theory cannot be formulated with either classic laws or at least classic probabilities. Here's my understanding...
1) There's a class of experiments like measuring the spin of an electron along an axis that only give binary answers like totally "up" or totally "down"
2) Repeating exactly the same experiment might give a different answer
It follows that the behavior of the electron cannot be deduced from a single experiment. Instead one has to do many experiments and the relative numbers of ups and downs give a probability. It then follows that one invents a theory that describes these probabilities as good as possible and the result are quantum mechanic probabilities, which are not even like classical probabilities (Bell's theorem violated, etc.).
But what, if some day in the future, someone could measure a new, so far undiscovered, "thing", e.g. a new property of elementary particles or a new field or whatever. If it turned out that this new "thing" was not binary but real-numbered and if it turned out that this new "thing" determined whether the spin at the end of the experiment was up or down, wouldn't it then be possible to throw away quantum mechanic probabilities and come back to a theory that is either totally classic or at least only involves classic probabilities?
To put the question another way: Apart from the observational fact (which I of course accept), that spin measurements so far only give binary answers, is there any other logical argument that would prevent a future experiment from bringing particle physics back to classical physics or at least to classical probabilities?
Thanks
Volker

Unknown said...

Is it a coincidence that there are the same number of constraints in the Riemannian integral(cosmology course) as there are group particles in the Standard Model SUSY and Grand Unificaiton course)?

Bart Kwezelstaart said...

Hey Lenny,

Great work! I am in high school and i am making a paper about special relativity. I was a bit confused when Susskind suddenly made a 'guess' while we were deriving. Thanks for posting the missing links!
I have a question though:
When it came to measuring the relative velocity between frame3 and frame1, Susskind said that you could just add the hyperbolic angle that corresponds with the relative velocity between frame2 and frame1, to the to the hyperbolic angle of frame 3 to frame 2. I made an example but i did not end up with a propper answer: (v= 3, ...m/s)
Could someone work out the right solution to the folowing exmple?
The relative velocity between a train and it's station is 2/3 of the speed of light. In the train is a car. The car and the train have a ralative velocity of 2/3 of the speed of light in the same direction as the velocity from the train relative to the station ( this to disclaim that the car might be standing still relative to the station. What is the velocity of the car relative to the station?
Thanks in advance to the person who solves this :)

regards from Holland,
Bart

Bart Kwezelstaart said...

I just solved the example i posted earlier today: If a train moves with 2/3 of te speed of light(c) relative to a station and inside the train is a car that also moves with 2/3 c relative to the train(in the same direction as the movement of the train), then how fast is this car moving relative to the station?
In this calculation omega is represented by @. The formula's i can be found in Susskinds lecture about special relativity that was uploaded to YouTube on 15-07-2008. He said he left it as an exercise. For those of you who didn't manage to solve it(like me until this morning), Here ya go :)

cosh@= 1/(1-(2c/3)^2/c^2)^(1/2)

cosh@= 1/0,7453....
= 1,3416....

@= inverse cosh(1,3416....)
= 0,8047....

2*0,8047....=1,6094....

cosh(1,6094....)= 1/(1-v^2/c^2)^(1/2)

(1-v^2/c^2)^(1/2)= 1/2.5999....

(1-v^2/c^2)^(1/2)= 0,3846....

1-v^2/c^2= 0,1479....

1-0,1479....-v^2/c^2= 0

v^2/c^2= 0,8520....

v^2= c^2*0,8520....
= 7,6580....*10^16

v= (7,6580....*10^16)^(1/2)

v= 2,7673....*10^8

S Alan said...

I would like to ask you for a way to understand the Doppler shift from the point of view of photons. It would seem one can have any photon energy one wishes merely by changing the relative velocity between the photon source and the photon detector. If an interaction is required to change the photon energy, how would you describe the interactions in the case of Doppler shifts.?

saurabh jankat said...
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saurabh jankat said...
This comment has been removed by the author.
saurabh jankat said...


Dr. Susskind , antiparticle and particle both are formed in space everywhere as Stephen hawking said and then annihilate then this process requires energy to form particle and antiparticle?also which particle and antiparticle is formed?

Ramez Ghosn said...
This comment has been removed by the author.
Alistair Hendry said...

Could Time be the Torch that lights the Hologram???

Alistair Hendry said...

Dear Sir,

Could time be the torch that lights the Hologram?????

Srijita Mukherjee said...

sir the carnot cycle is an idealised cycle and it was suppossed to be reversible..the refrigerator concept was based on this assumption of reversibility...yet refrigerators has been made in reality..how is that possible??

L Nigogosian said...

I am trying to get a better understanding of quantum mechanics and your book Quantum Mechanics The theoretical minimum and your lectures in the subject have made this possible. Thank You.
My question is the equation in page 285. How is the second equation derived from the first? How can Fi(x,t)be equal to both these equations?

John Fistere said...

How can we consider the surface of a black hole as a hologram representing the interior if it is so chaotic?

Duncan Deepcover said...

Dear Professor,

I understand that one of the things that raises some physicists eyebrows about the Holographic Principle is that it maps information from 3 spatial dimensions onto a 2-dimensional surface.

I am perplexed as to why only 3 dimensions are considered ... if M-Theory is correct, then wouldn't information from the 11 dimensions of subatomic strings have to be mapped as well?

Would 11-dimensional gravitons (if they in fact exist) also be part of the information stored on the 2-dimensional surface like everything else?

A Lapsed Physicist.

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IB ONLINE TUTOR said...

Contact No: 09899235249 or 9818369374
IB World Academy has been helping students excel in IB Math(HL,SL,Studies), Physics(HL,SL), Chemistry(HL,SL), Economics(HL,SL), and Business Management(HL,SL) by providing the right skills for success. Centrally located near Safdarjang Enclave in South Delhi, we have highly skilled and qualified teachers having over 7 years experience teaching different streams of IB Math, Physics, Chemistry, Economics, and Business Management. Our tutors possess B.Tech, M.Sc. (Math), B.Sc. (Math) and B.Ed. degrees. We measure our success by yours and take pride in delivering the highest quality of education service by using our experience and expertise in this field.We tutor students from Grades 7–12. Our students are from Pathways World School, GD Goenka World School, Shri Ram School, and American Embassy School, Lancers International School, Scottish High School, and other reputed IB schools in Delhi and Gurgaon. We have tutors with many years experience teaching International Baccalaureate (IB) Diploma, IGCSE. We provide one-to-one customized sessions between the tutor & student. We’re reputed for our outstanding results and proven success year after year.
IB World Academy is a leading exam preparation institute in Delhi and specializes in preparing students for GMAT, GRE, SAT, SSAT and LSAT exams.
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Meir Krukowsky said...

Dear proffessor Susskind,
I follow your video lessons with enthousiasm.I also read your books the theoretical minimum.
I have a question about timelike and spacelike lecture 3 (about 12 minutes)special relativity.In the one
case you can always find a lorentz transormtion to describe the particle motion and in the other case it is not
possible.I don't understand why.
I also have another question.Is'nt it so that our solar system is a physical system where information travels
instantaniously,F=ma requires no time.If this is true than signals travel much much faster than light.
Thank you very much in advance.
Thank you again for your lectures,without them i couldn't have study eventhough there are some good
books out there ex. Fleisch's student guide to vectors and tensors.Gilbert Strangs linear algebra and others.
Best Regards
Meir Krukowsky

MAURICE PANERO said...

TESTING

indelicato said...

Dear Professor Susskind can you please post the youtube subtitles in the lessons of the latest physics courses on the internet who have none? Thank you

Simthembile. Dlamini said...

Dear Prof

I hope you doing okay, I have been following your lecture videos on youtube for Cosmology, I have a question when you want to solve a(t) in-terms of w, where w=w(t) in other words it is not constant it varies with time. the w(t) from the EoS(Equation of State). please help Prof OR anyone who can be able to help please help me. simther4111@gmail.com that's my email address.

Simthembile. Dlamini said...

Dear Prof

I hope you doing okay, I have been following your lecture videos on youtube for Cosmology, I have a question when you want to solve a(t) in-terms of w, where w=w(t) in other words it is not constant it varies with time. the w(t) from the EoS(Equation of State). please help Prof OR anyone who can be able to help please help me. simther4111@gmail.com that's my email address.

Ken Abbott said...

Black Holes as neutrino factories? Yes.
Here's a specific mechanism by which Black Holes could emit neutrinos (and evaporate in the process).
http://www.math-math.com/2016/08/how-black-holes-could-be-neutrino.html

John F K said...

I took calc, linear algebra and diff eq 35 years ago and then pursued a career out of science. Would like to learn about tensors to understand Professor Susskinds GR lectures. Tried Schaum's outline but it's too shallow. Can anyone recommend a good tensor calculus textbook?
Thanks.

Leslie D said...

Hi,

I think the site you were probably intending to set up would have needded software for a forum, rather than a blog.

But my question. I was just wondering why the phrase "relativistic mass" has gone out of favour.

Erewhon Society said...

Wouldn't the CBR be the first "thing" to go over the 'Horizon' ?

Erewhon Society said...

Wouldn't the CBR be the first "thing" to go over the 'Horizon' ?

Kathleen and Dave Roberts said...

Heisenberg was out for a Sunday drive when he was pulled over by a police officer. The officers asked "do you know how fast you were going?" Heisenberg answer, "no I do not know how fast I was going, but I do know where I am at."

Kathleen and Dave Roberts said...

There is a hotel near the Stanford physics dept that has a sign over one of the beds that says: "Heisenberg may have slept here."

Kathleen and Dave Roberts said...

How many quantum physicists does it take to change a light bulb. One: one to turn the bulb, one to hold the ladder and three to renomalize the wave equation.

Kathleen and Dave Roberts said...

Why did the chicken cross the road? Whether the chicken crossed the road or the road crossed the chicken depends upon your frame of reference.

Kathleen and Dave Roberts said...

Three quarks walked into a bar together. (Of course they did, it has far, far, far too long ago when it was warm enough for them to walk in independently.)

Kathleen and Dave Roberts said...

Rene Descartes (a philosopher, but also a contributor to physics) was in a bar doing the two things he liked best: drinking beer and philosophysing. At closing the bar tender asked if he wanted a final drink. Descartes said: "I think not." With that, poof, he disappeared.

Kathleen and Dave Roberts said...

A neutron walked into a bar and ordered a beer. He asked how much he owed. The bartender said: "for you, no charge."

Kathleen and Dave Roberts said...

A proton walked into a bar and ordered a beer. The bartender asked if he was sure. The proton said: "i am positive."

Smart Tech said...

Hello sir. i actually have a question from cosmology. it is believed that before the existence of this vast universe it was in a form of nutshell. this concept given by the big bang theory confuses me a lot.
I actually have a question that if the universe existed in the form of nutshell then on what did the nutshell shaped universe stood upon or existed in?
Hope you will solve my problem.
Sincerely,
Gunjan Luitel
Grade- XI
Capital College and Research centre
Kathmandu, Nepal

Smart Tech said...

I would also like you to give some tips on my time theory on the-time-theory.blogspot.com
thank you

John Hensgen said...

Hello Professor Leonard Susskind:)
Is it possible for strong and weak energy to vary? Is this why the corona to be hotter than the surface of the sun? Is it possible for particle strings to be made up of virtual particles?

John Hensgen said...

Hello Professor Leonard Susskind:)
Is it possible for strong and weak energy to vary? Is this why the corona to be hotter than the surface of the sun? Is it possible for particle strings to be made up of virtual particles?

Tufail Abbas said...

Hello Professor,

When you say that 3-D reality has emerged from 2-D hologram, is it necessary to be located on a black holes, which is not verifiable, and not useful for our daily life.

Can't it be that the hologram is imprinted on electron , protons and neutrons itself. Why can't a finite area contain an infinite number of space (i.e. lines).

What do you think about it?

So if we have infinite numbers of lines on surface of particle (say like bunch of steel rods of infinitesimal size), it can continuously come out as perpendicular field out from the surface thus creating 3-D reality like a cage is made from steel rods. Bunch of steel rods do have a small volume, but the cage will have increased volume.

What is the exact problem with such reasoning about the nature of hologram.

Regards

Tufail Abbas
Independence Researcher of Physical Significance

Tufail Abbas said...
This comment has been removed by the author.
Tufail Abbas said...
This comment has been removed by the author.
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