Dec 6, 2018 · 1h 6m · y-combinator
Leonard Susskind on Richard Feynman, the Holographic Principle, and Unanswered Questions in Physics · Y Combinator
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Theoretical physicist Leonard Susskind discusses his fundamental methodology of resolving physical paradoxes, tracing major developments in quantum gravity, string theory, and the Holographic Principle while sharing reflections on scientific icons, ethics, and public education.
How this conversation actually went
Every chapter scored 0–10 on four independent dynamics. Hover any point for the reasoning behind the score. How this is scored →
The partners as informed peer 2.1 Guest teaching 4.6 Guest disagreement 2.9 The partners pushing back 1.3
speaking balance: gold is the partners, purple is the guest (3 minute bins)
Sharpest disagreement ▶ 0:30 Halting the opening premise on radicalism
Susskind interrupts the host immediately to dismantle the premise that his ideas are outlandish or alternative, asserting he is entirely conservative and mainstream.
Hardest push from the partners ▶ 27:21 Pushing back on the mainstream labelThe host directly challenges Susskind's redefinition of his work, arguing that any fringe idea that eventually gains broad adoption can retroactively be called mainstream.
Biggest teaching moment ▶ 8:35 Distinguishing trivial space LIGO from graviton collidersSusskind firmly corrects the host's analogy between space-based gravitational wave detectors and building an impossible galaxy-scale machine to detect single gravitons.
The partners hold their own ▶ 13:02 Referencing Cornell lecture skepticismThe host demonstrates deep preparation by citing a specific historical remark from Susskind's Cornell lectures where he distanced himself from dogmatic belief in string theory.
the scores for every segment, with the reasoning behind each
| Chapter | Topic | The partners as informed peer | Guest teaching | Guest disagreement | The partners pushing back | Why |
|---|---|---|---|---|---|---|
| Mainstream Physics vs. Radical Reputation | 1 | 5 | 6 | 2 | Susskind immediately halts the host to reject the premise that he is an unconventional radical, asserting he is the most conservative mainstream physicist imaginable. | |
| Defining Contrarianism in Physics | 2 | 4 | 3 | 1 | The host asks for examples of actual contrarians, and Susskind defines contrarianism versus free-thinking using Freeman Dyson and Gerard 't Hooft. | |
| From Plumber to Stanford Physics Insider | 2 | 4 | 2 | 1 | The host asks about Susskind's background as a plumber and where ideas originate, prompting an explanation of paradoxes and quark confinement. | |
| Graviton Detection and Technological Feasibility | 2 | 6 | 4 | 2 | When the host compares detecting individual gravitons to space LIGO, Susskind quickly corrects him by noting space LIGO is technologically trivial compared to an impossible galaxy-scale accelerator. | |
| The Discovery and Genesis of String Theory | 1 | 4 | 1 | 0 | Susskind details how recognizing harmonic oscillator mathematics in hadron scattering led to the formulation of string theory. | |
| Evaluating String Theory Beyond Rigorous Mathematics | 3 | 3 | 2 | 2 | The host demonstrates preparation by citing Susskind's Cornell lectures regarding his skepticism of string theory as a final physical description. | |
| The Imperative of a Grand Unified Theory | 2 | 5 | 4 | 2 | Susskind firmly rejects the idea that unified theories are optional, emphasizing that physical contradictions are intolerable. | |
| The Cosmological Constant and Anthropic Principle | 2 | 5 | 2 | 1 | Susskind explains the cosmological constant problem and Steven Weinberg's anthropic explanation in a multiverse setting. | |
| Black Holes and Information Storage | 2 | 5 | 2 | 1 | The host prompts a definition of information, leading Susskind to explain quantum bits and how black holes store almost all entropy. | |
| Origin and Validation of the Holographic Principle | 3 | 5 | 4 | 4 | The host pushes back on Susskind's claim of mainstream status by arguing fringe ideas merely become mainstream over time; Susskind counters that science is an explanatory validation process, not a popularity contest. | |
| Holographic Mapping and Reconstructing Quantum States | 2 | 5 | 2 | 1 | Susskind explains why 2D-to-3D holographic mappings are mathematically discontinuous jumbles rather than standard visual photographs. | |
| Analyzing and Dismissing the Simulation Hypothesis | 3 | 4 | 5 | 1 | Susskind dismisses the simulation hypothesis as an unhelpful infinite regress and cites Feynman's distaste for jargon-laden philosophical baloney. | |
| Scientific Discovery, Ethical Responsibility, and Societal Misuse | 3 | 4 | 3 | 2 | Host probes moral responsibilities of modern tech creators versus Manhattan Project scientists; Susskind distinguishes the scientific drive from political application. | |
| Lifelong Scientific Curiosity and Quantum Gravity | 2 | 6 | 2 | 1 | Susskind details the ER=EPR hypothesis connecting Einstein-Rosen wormholes with quantum entanglement and complexity theory. | |
| Quantum Teleportation Limits and Quantum Computing Applications | 2 | 5 | 3 | 0 | Susskind clarifies that quantum teleportation cannot exceed the speed of light due to classical decoding constraints and outlines quantum computer simulation capabilities. | |
| The Pedagogy of Physics and Demystifying Science | 2 | 3 | 1 | 0 | Susskind reflects on why he teaches public courses, explaining how honest pedagogy sharpens his theoretical concepts and demystifies real science for working people. |
Statements from this episode (30)
Susskind: When Conventional Approaches Fail, Outlandish Ideas Must Be Tried
“When you've tried everything and it doesn't work, there may still be something left that you haven't tried yet because you thought it was too outlandish. Well, you got to try it.”
Susskind: Contrarians Like Freeman Dyson Have High Probability of Being Wrong
“Like all contrarians, he's got a very large probability of being wrong.”
Susskind: Richard Feynman Was Mainstream, Not a Contrarian
“No, he was about as mainstream as you can be, but also had his own, he had his own very special scientific personality.”
Susskind: Modern physicists are pushed into rigid, overly mainstream training
“Well, unfortunately, I think you have to be really mainstream. Sometimes I think too much. Sometimes I think too much. By mainstream now, I mean people are often trained within a framework which is fairly tight and rigid.”
Susskind: Contrarians oppose mainstream views solely for the sake of it
“Free thinking, but that doesn't mean being a contrarian. A contrarian is somebody who is contrary just for the sake of being contrary.”
Susskind: Quantum Field Theory Originally Dictated All Particles Could Be Isolated
“From all that we knew about the subject as quantum field theory, the subject that governs particle physics, from all that we thought we knew, any kind of particle that exists should be possible to kick it out and observe it directly in the laboratory.”
Susskind: Space-based LIGO is technologically feasible and will be built
“It's trivial in the sense that in principle we can do it. We will do it. And it probably doesn't involve any technological hurdles, which are insurmountable.”
Susskind: Producing gravitons will remain insurmountable for a million years
“Building a machine that could produce gravitons At least for the next million years is going to be insurmountable. It's not, I think it's not going to be done. On the other hand, maybe I'm wrong.”
Leonard Susskind: String theory became mainstream despite its radical origins
“Which is extremely mainstream, you'll notice.
[571] Podcast Host: Which is super mainstream, yeah.
[572] Leonard Susskind: But it wasn't when we started it.
[574] Podcast Host: Correct.
[575] Podcast Host: Well that's where the idea, right.
[576] SPEAKER_02: R…”
Susskind: String theory cannot describe real particles without modification
“We know that the formal, by formal I mean mathematically rigorous structure that string theory became, it became a mathematical structure of great rigor and consistency that It, in itself, as it is, cannot describe the real world of particles. It has to be mod…”
Susskind: LHC gave no new information, leaving particle physics stalled
“We seem to have run out of new experimental data, even though there was a big experimental project the LHC at CERN. What if that is a great big machine that produces particles and collides them. And I would say I don't want to use the word disappointingly. Wel…”
Susskind: Dark energy is 120 orders of magnitude smaller than expected
“The dark energy is, Is a tiny, tiny minuscule fraction of what it could be. Why is it so small? 10 to the minus a 120 of what the natural expectation for it would be.”
Susskind: A vast, varied multiverse is the only sensible cosmological explanation
“No, it's not mine, but I think it's the only thing that does at the moment seem to make any sense, is to say the universe is extremely big, much bigger than we can see, and varied. Varied means it has properties which are different from place to place.”
Susskind: The anthropic principle is widely hated among physicists
“That's called the anthropic principle, and it's a widely hated idea among physicists.”
Susskind: Black holes store 10^10 times more information than ordinary matter
“Our world is mostly all black holes, it really is, in the sense that the information stored in matter is at least
let me think I think about 10 to the 10th, a factor of 10 to the 10th more information stored in black holes than anything else.”
Susskind: Stephen Hawking was wrong about information loss in black holes
“Stephen Hawking's very, very brilliant insight, even though I think he got the final answer wrong. It was very brilliant insight to ask what happens to the information that goes into black holes?”
Susskind: Maldacena's math validated the holographic principle for mainstream physics
“It wasn't, it didn't come in from the cold, shall we say, until the work of Juan Maldesena, who made a really rigorous, beautiful version of it, which now everybody believes. The mathematics of it was, it came from, it was a string theoretic construction where…”
Susskind: Mapping 3D space onto 2D boundaries produces visual discontinuity
“It is possible to map a three dimensional world onto two dimensions, but never in a way in which the two dimensional stuff looks anything like the thing you're mapping. It will look random. It will look it will look like a simply confused jumble of little tiny…”
Susskind: Quantum computation could reconstruct matter inside black holes
“With a sufficient kind of technology of quantum computation and so forth, and if we knew the precise rules by which black holes evolve, we could reconstruct from the quantum state of the horizon, we could reconstruct what fell in, what's inside, and so forth. …”
Susskind: Reality's 'Program' Is Nature's Laws and the Computer Is the World
“No, no, but I would say, of course we live in a computer program. The program is called the laws of nature, and the computer is, is, is the world.”
Susskind: Richard Feynman was deeply philosophical despite claiming to dislike philosophy
“Feynman this claimed to dislike Philosophy. He did dislike philosophy, but I'll tell you what that means in a minute. And yet he was the most philosophical of all physicists. He really was. He was a deep philosopher. When I say he didn't like philosophy, I mea…”
Susskind: Feynman hated building nuclear weapons and having fun doing it
“He hated the fact that he had participated, he hated the fact that he had participated in the invention of nuclear weapons, and he doubly hated the fact that he had so much fun doing it.”
Susskind: Physicists must discover everything and leave preventing misuse to politicians
“It's not, I don't believe it's the physicist's job to decide what should and shouldn't be discovered. From a physicist's point of view, everything should be discovered if possible. It is the job of politicians and other people of that ilk to make sure that thi…”
Susskind: Dangerous scientific discoveries cannot be hidden and will inevitably emerge
“First of all, I don't think you can hide it. You can't hide it. It's gonna come out. It's gonna come out.”
Susskind: Gravity rules likely originate directly from quantum mechanics
“My guess is that almost everything we know about gravity is coming straight from quantum mechanics and that there are equivalent rules of quantum mechanics which reflect the gravitational things.”
Susskind: Quantum entanglement and Einstein-Rosen bridges are the exact same phenomenon
“In very recent years, we found out that entanglement and Einstein-Rosen bridges are the same thing. That, in particular, an example would be if you have two black holes. Black holes have all kinds of internal structure to them. They're quantum mechanical objec…”
Susskind: Wormholes expand too quickly for anything to travel through them
“The problem is the wormhole grows and it grows so fast that you can't get through it... That's the way these Einstein Rosen bridges behave.”
Susskind: Quantum teleportation cannot enable faster-than-light communication
“In order to do quantum teleportation, you cannot do quantum teleportation without at the same time sending classical information from one place to another. Classical information means, you know, The dots and dashes, Morse code dots and dashes. You can have two…”
Susskind: Quantum teleportation provides security impossible with classical protocols
“It gives you absolute, 100% security that no classical non-quantum mechanical protocol could ever give you. But it can't be done faster.”
Susskind: Classical computers can never simulate 100 entangled qubits
“Classical computers can never be built big enough to explore more than 400, more than actually more than Probably a hundred qubits. A hundred qubits doesn't seem like very much. No classical computer can do the calculation of following what a hundred qubits do…”