Lecture 3 | Topics in String Theory

[@joabrosenberg2961]

Schwarzschild Metric and horizon; Alice going into the Black Hole 41:30; Bob never sees her getting into the BH 48:00; Thermodynamic of BH 58:00; BH Evaporation 1:15:00; Conservation of Information is the most basic rule of physics 1:37:00

[@Dyslexic-Artist-Theory-on-Time]

Could quantum mechanics represent the passage or Arrow of Time? This theory is based on just two postulates, 1.The first is that the quantum wave particle function explained by Schrödinger’s wave equation represents the forward passage of time or Arrow of Time itself photon by photon, quanta by quanta or moment by moment. 2. The second is that Heisenberg’s Uncertainty Principle that is formed by the wave function is the same uncertainty we have with any future event. No strings!

[@oscarheath5507]

@brian estremos String theory is basically the idea that the basic little things that make up all matter (e.g. the electrons going around atoms) aren't points or blobs, they're tiny tiny 'strings' - lines, either looped or just dangling, that wiggle around and drift through space Its useful because it is much easier to make string theory work with gravity than quantum field theory, and in fact gravity is an inevitable consequence of string theory Its been criticised though, because the energy scale on which it differs from normal particle physics is far, far higher than anything scientists could feasibly test - for the time being, it appears untestable Nonetheless it is theoretically very interesting and provides some very beautiful connections between seemingly unconnected ideas. It also helps make sense of Quantum Chromo-Dynamics, which is how the nuclei of atoms work, and which is almost impossible to accurately compute using Quantum Field Theory I hope this helps, peace and love

[@erikwislinsky5961]

Fantastically helpful comment, thanks so much

[@raemclellan7693]

Thanks for these great lectures! Assuming Bob (with the help of his magic SpaceX rocketship) can remain a fixed distance away as Alice falls into the black hole: From Bob's perspective, Alice is asymtotically slowing down as she approaches the event horizon and she appears to never cross over. However, whatever light illuminating Alice also has a flux, or number of photons/time. And since Alice's time is slowed from Bob's perspective, the number of photons depicting Alice reaching Bob decrease with time as well. So Alice appears dimmer and dimmer as she approaches the event Horizon and eventually can no longer be seen by the human eye. Perhaps with an integrating camera, enough photons could be caught to build and image. But at some point, Bob will no longer be able to see Alice. Like an old soldier, she just fades away. It would be interesting to know how close Alice has to be to the event horizon before time dilation is sufficiently great to affect the photon flux reaching Bob and how long Bob would have to wait to see that effect. Also how the required proximity compares to Alice's dimensions of height, width, etc. Speaking of which, what effect does the event horizon have on the chemical bonds of Alice's constituent atoms? Do the bonds break as they cross the event horizon? Would the virtual photons comprising the electrodynamic forces binding Alice's molecules be disrupted? Perhaps if she's traveling fast enough, the time it takes to move an intra-molecular distance wouldn't be enough time for the atoms to move relative to each other, that they wouldn't "re-connect" properly once they both passed the event horizon? Or would the quantum uncertaintity and thermal energy be sufficient to displace atoms in that time so they reconnect to different atoms or not at all after the time they were incommunicado during the passage? How quickly (in her rest frame) must Alice pass thru the event horizon to avoid disintegration? Is free-fall truly fast enough at any speed? I believe there will also be some red-shifting of Alice's image as well, as the photons climb up out of the gravity well. But that is probably small and finite as it comes only from the gravity gradient between Bob's position and the event horizon, which is a fixed amount and not something that diverges to infinity, unlike the time dilation as Alice approaches the event horizon.

[@KrzysztofDanielCiba]

I was really waiting for that cookie to show up. :-) I wish I had such a great mind lecturer during my study times.

[@water0heaven]

At around 15:40, that omega he mentioned is in fact twice the area surrounded by the three curves, which is not the concept of an ordinary angle, to be precise.

[@alphaomega1089]

Only a quick note on information conservation with that eraser coming to rest. The information has been conserved. It transferred that information into time and space. Even the mass is aware of its motion and the person who pushed it (memory of doing so physically or mentally remembered to predict it'll do the same again). Nothing is lost or it'd disappear from our time frame. We are not important. We are only memory storage. Atoms are we. We are so far down that intellectual tree it is ridiculous to assume otherwise. The illusion of tricky is for those unable to remember one and the same. We don't have to know everything.

[@NatarajanPhysicist]

professor Leonard susskind you are genius always

[@bindon8581]

00:57:14 "Einstein, incidently, , did not believe in Black Holes." There's something curious here. Bob can only approach the speed of light, having mass, yet he escapes the Black Hole Horizon, the point of no return. His trajectory or geodesic saves him. In other words, gravity or inertia saves him, like a slingshot effect on a spacecraft around the moon or a planet. Let's reiterate, the acceleration away is a product of the inertia. [ let's assume there's nothing special, no extra force, pulling Alice into the massive BH. Leonard did say the BH was huge. But if there's nothing out of the ordinary at the Horizon, how has it got so huge, the BH? What size must it get before it's no longer an attractor? One assumes it was gobbling up stars and material, originally; or why is at the very centre of galaxies, if it 's not an attractor? Don't tell me BHs are conjectural? If that's the case on the 'easier to see' astrophysical scale, why should I believe anything I'm told on the infinitesimal scale, the scale of strings? Maths isn't proof; it's axioms are deductive, not Popperian. 2 + 2 = 4 isn't objective; nor is it true in other dimensions, even 3 dimensions. To see that, write 2 + 2 = 4 on A4 paper, then fold it in half!!! "Einstein, incidently, , did not believe in Black Holes." I don't know what to believe anymore. Einstein was a realist. Modern physicists are Hans Christian Andersons. ]]

[@bindon8581]

Qh, spoke too soon. BHs attract by being colder than their surroundings. If we want tp be conjectural, we can assume experimental physicists are trying to make radiating or contracting BHs as a source of energy. Personally, I tie a canister to the back end of a cow to collect the methane. Much safer. Cows are blamed for rising greenhouse gas. Either the sun is getting hotter or cattle are responsible for rising temperatures, not the burning of fossil fuel. Yeh, right. CO2 is now at nearly 410 ppm, a rise of 130 ppm post Industrial Revolution. Mass extinctions occur around 500 ppm, about 20 years on present trends.

[@davidwilkie9551]

If the composition of the universe is read "topically" as a physical object, then measurement and mathematics have the most descriptive attributes of reproducibility, to transfer learning techniques from lecturers to students. The quantifiable mechanism, mathematics, is an inherent function of spacetime, and the infinite distributions of relative intensity of information in Quantum Fields/Feynman Diagrams, is used to represent the subject of description. Ie the representation is a low intensity copy, a relocation of the approximate concept essence that is itself a phaselocked bonding of time-duration cycles; ..mathematical logic made manifest as a rule of measurement. The features and phenomena of what is a QM expansion/inflation of timing, is an instantaneous image in spacings composed of spin/reflection, "strung" in a temporal tension state as exemplified in crystals, layer upon layer of the QF of time. Typical reliance on the stability of measurable space-length is not applicable to dimensions other than "free space" , and even that is "gravitationally" unstable because all phenomena are scaled versions of quantum foam bubbles and divergence/convergence of information intensity. Big Bang and Black Hole models are dominated by the actual mathematical QM projections of relative timing, not "classical" assumptions and if there's conflict in comprehension of phenomena, it's due to the order in which concepts are assembled mentally. So the artist's representational techniques of superimposed layering of 2D images, that flattens the universal picture into a plane, is equivalent to explaining/illustrating the QM Inflation process by "Normalized" String Theory, or orientating "jump" timing, ...unraveling the vortex of spacetime from the universal vanishing point. Ie the temporal representation is obvious in the visual sense, and it's not prioritised as it exists because of "overfamilarity" (?). Also, de-personalized information is hard to come by in the human knowledge libraries, everybody wants credit financially, and credibility of belief, even though scientific research is an abstract methodology of reductionist simplification. (Present company excepted?)

[@jreedmcu1]

about to graduate, wheew! nothing to be afraid of, feel like you accomplish something! One word of advise, "Finish."

[@apspacking]

Leonard will never pass away. A grate man never dies. Then, please later on send your cookies for me. Thank you.

[@jreedmcu1]

your videos always make me hungry

[@FirstRisingSouI]

I watch these lectures in 1.5x speed. It makes me feel like a badass.

[@Stopa42]

+FirstRisingSouI Nah... He just speaks so slow to watch in normal speed and do not fall asleep :-).

[@abhinandan008]

2x speed. Alpha badass

[@grunder20]

Excuse my ignorance, but what is String theory?

[@DanielFBest]

Beautiful!

[@Onoma314]

When this great man passes from this life, I will visit his grave and bring not flowers, but cookies :)

[@randymartin5500]

Brilliant clarification to the student at the end of the lecture: The entropy doesn't define the probability distribution . Probability distribution defines the entropy. Entropy is one number and one number cannot define the i-th p

[@postbodzapism]

And 2 is 1

[@stevenmildred55]

This isn't the string theory I was thinking of.

[@NoActuallyGo-KCUF-Yourself]

You're talking about TIMECUBE aren't you?

[@Dilaton100]

2 = 1 in Planck units LOL :-D I just love these jokes

[@angelmorales2241]

Mire ha mi y tengo ke exponer sobre Hoyente local permanente y los polos sur o norte oeste y ya se trata de brujula y conpas cosa seria en un diputa a ditansia lugar faborito no exsite es un trabajo y movimientos de paso un Ofisina de ufolojia mi propuesta

[@TheShenergy]

Cafe information open 24/7 :) wicked comment Justin! :D u fractal me! lmao and going for a snack.

[@UristMcTubedwarf]

im afraid of collage now...

[@rmerkle1]

Type "True Theory of Everything Quadrant Model of Reality 1" into KZbin for the theory of everything.

[@lesterakrho5734]

LoopOkip

[@jreedmcu1]

:)