tag:blogger.com,1999:blog-2240954547063076010.post7797502399248012496..comments2017-10-19T07:20:04.200-07:00Comments on Susskind's Blog: Physics for Everyone: Leonard Susskindnoreply@blogger.comBlogger597125tag:blogger.com,1999:blog-2240954547063076010.post-58610986072917810132017-10-19T07:20:04.200-07:002017-10-19T07:20:04.200-07:00sir we have wave function in form of Aexpi/h(Et-...sir we have wave function in form of Aexpi/h(Et-px).....lets think mathematically as expected if we derivate wrt position i.e., gradient what will happen derivative of exponential wold come back to be exponential and we will bring p down....i.e., Pacting on Wavefunction=p times wave funcion..........my quesion is why dont we derivate wave functin with respect to momentum so that we will bring x down....and that must be equal to positon operator....but in quantum mechanics we have position operator as x why is that so? thanksAbrar Naqashhttps://www.blogger.com/profile/10332296427535954677noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-28347197316088860052017-09-09T09:05:57.429-07:002017-09-09T09:05:57.429-07:00professor, Is there a conclusion to newton bucket ...professor, Is there a conclusion to newton bucket experiment ,I searched the net but there was no satisfactory explanation ,can you please explain it ?Mayank Vashishthahttps://www.blogger.com/profile/05105086155395569008noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-28391593949526565202017-08-13T16:36:04.090-07:002017-08-13T16:36:04.090-07:00Hi Dr. Susskind,
It's a pleasure to have you ...Hi Dr. Susskind,<br /><br />It's a pleasure to have you on the net. I just knew of this blog while I was watching your lectures on relativity from 2008. Congrats for your brain and hard work! :)<br /><br />I was wondering what happened at some point in time that the four dimensions of space and time did not solve all the problems and scientists had to increase the number of dimensions finally to 11, if I'm updated enough!?<br /><br />Thanks.<br /><br />Best,<br />ErfanErfan mohagheghianhttps://www.blogger.com/profile/17380360420079092875noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-60420700587059229462017-08-13T16:32:57.411-07:002017-08-13T16:32:57.411-07:00This comment has been removed by the author.Erfan mohagheghianhttps://www.blogger.com/profile/17380360420079092875noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-15575966685216904462017-06-25T18:16:14.766-07:002017-06-25T18:16:14.766-07:00Dr. Susskind feels good to know you want to help p...Dr. Susskind feels good to know you want to help people to provide them knowledge on physics and astronomy , not just through your video lectures but also through blog ...<br />Thanks and professor after lots of continuous thinking I came to conclude Einstein's view point of the expansion of the universe might be wrong and we actually don't need any critical density for contraction of universe because I think it started contracting right after big bang ... Please correct me professor if I'm wrong and take care ......Diwasthakurhttps://www.blogger.com/profile/02583217904301832298noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-79684564102013899812017-06-25T18:01:39.774-07:002017-06-25T18:01:39.774-07:00Dr. Susskind , I've always been respected you ...Dr. Susskind , I've always been respected you and taught from you but I've finally found a theory that confirms some topics of Einstein's GR might not be correct and that's about the expansion of the universe and we actually don't need any critical density for contraction of universe because I can say our universe is contracting right after all matters formed . I used Newton's simple laws to make this theory ..... <br /> Dr. Susskind please reply me if you want to check whether its possible or not ...<br /> Thank you Diwasthakurhttps://www.blogger.com/profile/02583217904301832298noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-46705976773390073932017-04-25T15:45:41.310-07:002017-04-25T15:45:41.310-07:00Professor Susskind's lecture on entanglement s...Professor Susskind's lecture on entanglement seems to contain an error which undermines the breaking of the inequality.<br /><br />[ see<br />Lecture 5: Quantum Entanglements, Part 1 (Stanford) October 23, 2006<br />From time = 28 mins to time = 1 hour 12 mins. Susskind, L.<br />https://www.youtube.com/watch?v=XlLsTaJn9AQ&p=A27CEA1B8B27EB67<br />AND<br />otes on Susskind’s lecture 5, courtesy of paul@lecture-notes.co.uk<br />http://www.lecture-notes.co.uk/susskind/quantum-entanglements/lecture-<br />5/violation-of-bells-theorem/ ]<br /><br />0.073 is the proportion calculated for A and notB (when theta = 45 degrees). Ie for Alice = 1 and Bob = -1. But such a low value of the proportion in A and notB implies a 2x2 table of measurements with a positive correlation. The four proportions in the cells are 0.073, 0.427, 0.073 and 0.427. The smaller proportions must be in the diagonal cells to obtain a negative correlation as fitting in the Bell experiment. Ie 0.073 is appropriate for cell Alice = 1 and Bob = 1. So the inequality AB’ + BC’ ≥ AC’ was not shown to be broken.ben6993https://www.blogger.com/profile/11246990849377879772noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-49279408972225272782017-01-17T11:11:24.596-08:002017-01-17T11:11:24.596-08:00I am sabelo zwana from sa doing my first at mathem...I am sabelo zwana from sa doing my first at mathematics and mathematical statistics i have been trying to understand theory of relativity can u please explain it to me in detailUnknownhttps://www.blogger.com/profile/07792883379653033832noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-34118741300186700992016-11-17T05:28:34.556-08:002016-11-17T05:28:34.556-08:00Dear Prof. Susskind,
The spin ope...Dear Prof. Susskind,<br /> The spin operator in x direction applied on |u> state will give either |r> or |l> with 50 % chance. But in Lecture 6 and in appendix(The theoretical minimum- Quantum Mechanics), it's shown to produce a |d> state. How can be it possible, when a measurement in x direction will only give |r> or |l>. The blog seems dead for a long time, but I like to get the answer. ANONYMOUShttps://www.blogger.com/profile/15690456117804072243noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-9949738341078926772016-11-03T11:32:46.494-07:002016-11-03T11:32:46.494-07:00Hi,
In your presentation on 'Why is Time a On...Hi,<br /><br />In your presentation on 'Why is Time a One- Way Street?' Published on YouTube on July 16, 2013 (https://www.youtube.com/watch?v=jhnKBKZvb_U ) you have very well explained how time is a one way street but I am getting confused since space-time is treated as one then how would you explain the same phenomena for space-time as one? Can one way street of time be defined as a consequence of homogeneity of space as every point in space is center? Can you please recommend me some paper so that I can understand this concept better? <br /><br />Thank you !Shivani Singhhttps://www.blogger.com/profile/09677294112333441523noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-36497456487245345372016-10-21T05:09:56.224-07:002016-10-21T05:09:56.224-07:00Sir, i'm curious to know if Principle of Least...Sir, i'm curious to know if Principle of Least Action is an axiom or it has got some proof. How can one check the validity of Principle of Least Action for some generalised case. Abhishek Vermahttps://www.blogger.com/profile/05418163665595058091noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-90183468468166664762016-09-20T08:59:58.390-07:002016-09-20T08:59:58.390-07:00Dear Leonard Susskind
Recently I read your magnif...Dear Leonard Susskind<br /><br />Recently I read your magnificent book; "The Black Hole War".<br /><br />I enjoyed reading it even though I daily work as a clerk within tax law and valuation in Denmark. <br /><br />Two questions kept bothering me all the way through. I hope you will take a little time to clarify these for me:<br /><br />1) How does the premise that entropy is connected to heat (excited molecules rumbling around in a tub of water) cohere with heat created from high pressure? I imagine that heat produced in mid-earth would have very low entropy given that atoms/molecules are fixed and locked by dense pressure. Geologists expect large crystals to be found in mid-earth, and these crystals would have no entropy at all. How to explain this difference with heat/entropy?<br /><br />2) From Bob's point of view objects falling through the horizon of a black hole are stuck on the horizon. As I understand it, this phenomena is caused by time gradually slowing down as the objects approach the horizon. Am I correct to assume that light doesn't play a role on the perception of these objects being stuck, given that the gravity of the black hole cannot slow down the speed of light - only at most deplete its energy?<br /><br />Finally I want to thank you for a wonderful reading experience.<br /><br />Sincerely,<br /><br />Jonas Brønd, DenmarkJonas Brøndhttps://www.blogger.com/profile/11280755179314327182noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-77089053418717184522016-09-16T13:23:53.380-07:002016-09-16T13:23:53.380-07:00Dear Professor Susskind,
Is it not, that every ent...Dear Professor Susskind,<br />Is it not, that every entengled pair of particles creates its own wormhole to send informations through time and space... Information passage through time and space is instant, that means entenglment between particles worped time and space to send information... Thats definition of wormhole by default... I would like to get your intell about this...<br />Btw you can use entenglment for communication device during the deep exploration of cosmos... Informations from our probes can use communication device which carry entegled pairs of particles with ones at the Earth and send informations much faster then using electromagnetic signals or any velocity limited ways of travel... I hope my idea help u construct something usefull ...marjan gajovichttps://www.blogger.com/profile/17368004517394990265noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-57449308663743816742016-08-30T00:54:21.592-07:002016-08-30T00:54:21.592-07:00If there was a simple axiomatic way to describe a ...If there was a simple axiomatic way to describe a whole universe, where according to a few rules everything we saw around us was emergent and if it was short to, about 15 or so pages, would you like read about it?<br /><br />https://docs.google.com/document/d/1oINEHGo5ADUcrd0IabKHZQZONkT1cbe1EkrlxE8xlps/edit?usp=sharingBenjamin Brownhttps://www.blogger.com/profile/15987263543552997861noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-91987389839935741492016-08-26T08:38:13.400-07:002016-08-26T08:38:13.400-07:00Summary
Both Dr. Hawkings and Dr. Susskind are cor...Summary<br />Both Dr. Hawkings and Dr. Susskind are correct that information is both conserved and destroyed. <br />To elaborate, discrete particle information is destroyed over time due to entropy but the information of where, when and how the particle existed over time is essentially preserved in the standing quantum wave functions. When one wave function collapses upon observation another more complex, more information containing wave function is created waiting to interact with the next observed wave/particle duality outcome. For example, the double slit experiment with single release events.<br />Information that exists as a continuous analogue form as a quantum wave function represents the imaginary component* of the information stored in what is the white hole spherical surface of an expanding sphere (as often described in the holographic model) and this wave function has no discrete singularities but oscillates possibly on the plank scalre and on the rebound so to speak for all intents and purposes this goes backwards in time as limited by HUP.<br />*http://www.hawking.org.uk/the-beginning-of-time.html (please see subscript below for excerpt from the above lecture) Ref 1<br />The above information is what is used by QED to “keep track” of the individual discrete particles that make up the universe and represent for all intents and purposes a physical digital (discrete elementary particles) that exist in two states until observed by or interacted with another analoque wave function.<br />Now the interesting aspect of this comes from Dr. Edward Fredkin and his work on “reversible computing”:……………his quote :” In 1982 Fredkin and Toffoli proposed the Billiard ball computer, a mechanism using classical hard spheres to do reversible computations at finite speed with zero dissipation, but requiring perfect initial alignment of the balls' trajectories, and Bennett's review[7] compared these "Brownian" and "ballistic" paradigms for reversible computation.” Is basically identical to his billiard ball computer but we are suggesting the universe and its discrete individual particles represent a three dimensional billiard table that behaves more like a digital abacus where information is temporarily encoded as three dimensional objects that behave like both a particle and wave until observed.<br />Reversible computing is a model of computing where the computational process to some extent is reversible, i.e., time-invertible. In a computational model that uses transitions from one state of the abstract machine to another, a necessary condition for reversibility is that the relation of the mapping from states to their successors must be one-to-one. Reversible computing is generally considered an unconventional form of computing.<br /><br />Now the interesting part is what Dr. Brian Greene blah blah says (wow this is going to be hard to find)<br /><br />https://www.youtube.com/watch?v=atMuFCpxnUQ&google_comment_id=z12zejcy0zu2y1giz04ch1bwmtyli1zghoc0k (at seven minutes) “layer based on information” this is consistent with Dr. Hawkings online lecture “by virtue of that object having been there but moved on”.<br /><br />Ref 1<br />In fact, James Hartle of the University of California Santa Barbara, and I have proposed that space and imaginary time together, are indeed finite in extent, but without boundary. They would be like the surface of the Earth, but with two more dimensions. The surface of the Earth is finite in extent, but it doesn't have any boundaries or edges. I have been round the world, and I didn't fall off. <br />This says that in the imaginary time direction, space-time is finite in extent, but doesn't have any boundary or edge. The predictions of the no boundary proposal seem to agree with observation. The no boundary hypothesis also predicts that the universe will eventually collapse again. However, the contracting phase, will not have the opposite arrow of time, to the expanding phase. So we will keep on getting older, and we won't return to our youth. Because time is not going to go backwarhappy loserhttps://www.blogger.com/profile/14419547681096912793noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-25065955993489130692016-07-22T13:24:05.528-07:002016-07-22T13:24:05.528-07:00Dear Professor Susskind,
Thank you for believing t...Dear Professor Susskind,<br />Thank you for believing that deep understanding of physics should be available to all those who seek it.<br />I deeply enjoy viewing your Stanford lectures.<br />please review my latest publications in slide share regarding the missing anti matter and the non locality of entanglement.<br /><br />http://www.slideshare.net/eransinbar1/anti-matters-gravity-paradox<br />http://www.slideshare.net/eransinbar1/quantization-of-photonic-energy-and-photonic-wave-length<br /><br />I think you will find it very interesting.<br />I am very interested to hear you opinion.<br />Thank you so much <br />Eran Sinbar<br /><br />Eran Sinbarhttps://www.blogger.com/profile/01433460105989331960noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-70657055368389325182016-07-22T00:05:50.312-07:002016-07-22T00:05:50.312-07:00Dear Professor Susskind,
My name is Sayan Datta a...Dear Professor Susskind,<br /><br />My name is Sayan Datta and I am writing from India.<br /><br />I have watched most of your lectures; and many of them more than once. I always had a strong desire to understand some advanced physics, and your lectures were my first genuine introduction to the field after some failed attempts with some books and courses. I thank you for the lectures, which to me were excellent not only because of the ease with which it covered difficult material, but also because they were a deeply honest and genuine effort at reaching out.<br />I have also read your two books based on the lectures and have been eagerly waiting for the third. I hope it comes out soon.<br /><br />Thanks again,<br />SayanSayan Dattahttps://www.blogger.com/profile/10471336056338860961noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-90770263452373786002016-06-21T04:17:30.190-07:002016-06-21T04:17:30.190-07:00I am followingI am followingBernard Kamauhttps://www.blogger.com/profile/08263859059214189113noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-32859834945049954812016-05-19T20:57:04.378-07:002016-05-19T20:57:04.378-07:00it's it as possible to do it on a x y plan ,as...it's it as possible to do it on a x y plan ,as in visual bacic<br /> circle(X +-a,Y+-b)Ri-+ri1(Red-+red[limit1],0,0)<br /> circle(X +-a,Y+-b)Ri-+ri2(0,Green-+green[limit2],0)<br /> circle(X +-a,Y+-b)Ri-+ri3(0,o,Blue-+blue[limit3])<br />i hope so because that the program Im trying to put to together to study it<br />love the lectures great chatting with you :)Unknownhttps://www.blogger.com/profile/06748931406994807633noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-57053676795126654732016-04-16T09:52:45.130-07:002016-04-16T09:52:45.130-07:00I've been watching the lectures of particle ph...I've been watching the lectures of particle physics. I have a question. Are there any baryons similar to the proton and neutron having a spin of 1/2 and three quarks having the same flavor? Why doesn't the proton decay into a spin 1/2 baryon having three up quarks?Benhttps://www.blogger.com/profile/18424039278472445626noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-9219984096871694922016-03-06T22:02:41.116-08:002016-03-06T22:02:41.116-08:00This comment has been removed by the author.Abhishek Vermahttps://www.blogger.com/profile/05418163665595058091noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-71347005553460770792016-03-02T17:44:51.924-08:002016-03-02T17:44:51.924-08:00Sub: Regarding Energy Momentum Tensor in General R...Sub: Regarding Energy Momentum Tensor in General Relativity<br /><br />Dear Professor Susskind,<br /><br />First of all, thank you for making your lessons accessible to everyone. I was going through your classes on General Relativity and in one of the classes you mentioned that the gravitational waves are an example of Energy Momentum Tensor and therefore, Ricci tensor being zero while the Riemann curvature tensor is non-zero.<br /><br />I was wondering if either dark matter or the dark energy could be another possible example for the same case because I read somewhere that even though both of their (dark matter & dark energy) effects are observed, they are not visible. Please do correct me if my assumptions are wrong.<br /><br />Thanks,<br />PrudhviPrudhvi Raj Varma Chhttps://www.blogger.com/profile/05661438344179482834noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-22736734297468928572016-02-29T13:28:22.531-08:002016-02-29T13:28:22.531-08:00I just watched the video about universe being a ho...I just watched the video about universe being a hologram and id just like to say it sounds more to me like ur saying our universe is a blackhole in another universe.<br /><br />OliverOliver Falkhttps://www.blogger.com/profile/00730151754637842012noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-4225803211062493552016-02-22T21:49:18.663-08:002016-02-22T21:49:18.663-08:00This comment has been removed by the author.Tian Kunhttps://www.blogger.com/profile/18211440359807834127noreply@blogger.comtag:blogger.com,1999:blog-2240954547063076010.post-79354367398521135322016-02-22T21:45:11.848-08:002016-02-22T21:45:11.848-08:00Dear Leonard Suskind,
I am a graduate student .It ...Dear Leonard Suskind,<br />I am a graduate student .It is quit excited to contact you here . I want to have a deeper learning of string theory and superstring theory . Can you give me a recomendation of some textbooks .(P.S : My major are mathematics and physics as a undergraduate student before ).<br />Sincerely,<br />K.T.Tian Kunhttps://www.blogger.com/profile/18211440359807834127noreply@blogger.com