From: mk_thisisit
The discussion takes place in Los Alamos, New Mexico, a site famously known as the base where the nuclear bomb was created, a place that irreversibly changed the world of science. 01:52:00 01:55:00 01:57:00 02:00:00 This is the setting for an interview with Professor Wojciech Żurek, described as one of the most outstanding physicists globally. 02:06:00 02:09:00
Bridging Classical and Quantum Physics
Professor Żurek is noted for his work in combining classical physics with quantum physics, a feat previously unachieved by others. 02:17:00 02:20:00 02:22:00 His research focuses on the “point of contact” between these two realms. 00:54:00 17:59:00
Decoherence
The core concept connecting classical and quantum physics is decoherence. 02:30:00 02:34:00
- Einstein’s Concern: Albert Einstein, a “father” of quantum mechanics who later distanced himself, questioned how macroscopic objects appear in definite states when quantum mechanics allows for objects to be in multiple states simultaneously (e.g., a glass being “here and there”). 02:40:00 02:53:00 02:56:00 03:00:00 03:03:00 03:07:00 03:12:00 03:16:00 He argued that this contradicted observation. 04:06:00 04:09:00 04:12:00 04:15:00 04:19:00 04:23:00 This multi-state existence is called quantum superposition. 04:38:00 04:41:00 04:43:00 04:46:00
- Role of Measurement and Environment: In quantum physics, states are poorly defined until a measurement is made. 05:31:00 05:33:00 05:36:00 05:38:00 A “measurement” doesn’t require a person or device; any correlation that transfers information from an object to its environment (including observers like us) acts as a measurement. 05:52:00 05:55:00 05:58:00 06:00:00 06:03:00 06:07:00 06:09:00 06:14:00 For example, photons and air particles in the environment “know” where a glass is, and we “know they know” by observing it. 06:18:00 06:21:00 06:23:00 06:26:00 This interaction causes the quantum system to “cease to exist” as a superposition, leading to a disruption of coherence, which is decoherence. 06:34:00 06:35:00 06:38:00 06:39:00
- Decoherence’s Effect: The transfer of information about an object’s location prevents it from existing in multiple places simultaneously; it must “decide” on one location. 06:42:00 06:45:00 06:46:00 06:49:00 Decoherence removes the information that previously allowed for superposition. 10:01:00 10:04:00 10:08:00 10:12:00
Quantum Darwinism
Professor Żurek is the creator of Quantum Darwinism. 00:10:00 00:13:00 00:14:00 01:11:00 02:11:00 08:48:00 08:50:00 08:52:00
- Beyond Decoherence: While decoherence explains how superpositions are “mowed down,” 10:16:00 10:20:00 10:23:00 10:33:00 10:36:00 10:38:00 10:40:00 10:44:00 10:47:00 10:49:00 10:52:00 10:55:00 10:59:00 quantum Darwinism goes further. It posits that environmental factors not only select quantum states that can survive interaction (called “Pointer States” 09:37:00 09:41:00) but also cause information about these states to be replicated in many copies. 08:54:00 08:58:00 09:00:00 09:03:00 09:08:00 09:12:00 09:14:00 10:08:00 10:10:00 10:30:00 10:40:00 11:01:00
- Information Replication: We perceive classical reality because information about certain quantum states is replicated in billions of copies through interaction with the environment (e.g., photons). 11:49:00 11:54:00 11:59:00 12:03:00 12:07:00 12:10:00 This allows observers to obtain information without directly interacting with the object. 11:05:00 11:13:00 11:16:00 11:22:00 11:25:00 11:27:00 11:31:00 11:34:00 11:36:00 11:40:00 The environment ensures that these “surviving” states are duplicated. 12:27:00 12:29:00 12:33:00 12:36:00 12:39:00 12:44:00 12:47:00 12:49:00 12:50:00
- Darwinian Analogy: The theory is named “quantum Darwinism” because it involves a selective process where only certain “fit” quantum states (those resistant to environmental disturbance) survive and have their information replicated, akin to natural selection. 12:52:00 12:55:00 12:58:00 13:04:00 13:07:00 13:08:00
Unification Theories and Forces
Professor Żurek’s work focuses on deriving how the classical world emerges from quantum states, which differs from the common understanding of a “great unification theory.” 17:35:00 17:38:00 17:42:00 17:44:00 17:46:00 17:49:00 17:52:00 17:55:00 17:57:00
- Grand Unification Theory: This typically refers to a deep mathematical formula that aims to unite all fundamental forces. 15:53:00 15:56:00 15:59:00 16:03:00 This concept began with the unification of electricity and magnetism by Maxwell. 16:33:00 16:36:00 16:41:00 16:42:00 Later, electromagnetism was unified with weak interactions. 16:50:00 16:54:00 Theories also exist to unify strong interactions. 16:57:00 17:01:00 17:04:00
- String Theory: String Theory claims to unify these three interactions with the general theory of relativity. 17:14:00 17:17:00 17:22:00 17:25:00 However, it is not considered particularly convincing by some, as it has not yet predicted what is actually happening in our universe. 29:50:00 29:52:00 29:55:00 29:57:00 30:00:00
Gravity
Gravity, according to Professor Wheeler, is not a force but rather the way space is curved. 00:19:00 00:21:00 00:24:00 20:18:00 20:20:00 20:23:00 Objects move along straight lines in this curved space. 20:26:00 20:29:00 20:31:00
- Gravitational Waves: The detection of gravitational waves, an achievement recognized by a Nobel Prize, significantly advanced our understanding of gravity. 20:54:00 20:58:00 20:59:00 21:04:00 21:05:00 21:10:00 21:13:00 21:15:00 21:17:00 21:20:00 Signals from gravitational waves, however, pose new questions as they don’t entirely fit current theories about the universe’s origin, being “too big” or in an unknown range. 21:34:00 21:38:00 21:41:00 21:45:00 21:48:00
Origin of the Universe and Physical Constants
Deep questions arise about the universe’s existence and its fundamental properties. 27:43:00 27:47:00 27:49:00 27:52:00 27:56:00 27:59:00 28:01:00 28:03:00 28:06:00 28:09:00 28:11:00
- Big Bang and Inflation: Theories like inflation and the Big Bang describe how the universe began. 28:20:00 28:22:00 28:26:00 28:30:00 28:33:00 28:35:00
- Physical Constants: A profound question is what created the physical constants and laws. 29:02:00 29:04:00 29:07:00 29:09:00 This was a favorite question of Professor Wheeler, Żurek’s mentor. 29:12:00 29:15:00 29:19:00 29:22:00 29:24:00 29:27:00 29:31:00 29:32:00
- Kibble-Żurek Mechanism: This mechanism, co-created by Professor Żurek, describes what happens when the universe cools after the Big Bang, leading to phase transitions and symmetry breaking. 40:36:00 40:38:00 40:42:00 40:46:00 40:51:00 40:55:00 40:58:00 41:02:00 41:04:00 41:06:00 41:09:00 41:12:00 41:13:00 41:16:00 41:20:00 41:25:00 41:29:00 41:32:00 41:35:00 41:39:00 41:43:00 41:47:00
- Phase Transitions: Similar to water crystallizing, phase transitions involve systems choosing specific directions or symmetries. 42:06:00 42:08:00 42:10:00 42:13:00 42:17:00
- Topological Defects: If these choices of symmetry cannot be reconciled, “topological defects” occur. 42:27:00 42:30:00 42:33:00 42:37:00 42:39:00 42:42:00 42:45:00 42:48:00 42:58:00 43:00:00 43:04:00 43:07:00 These are stable regions where symmetry cannot be defined due to surrounding continuous symmetries. 44:25:00 44:27:00 44:30:00 44:33:00 44:36:00 44:41:00 They are associated with energy and heavy particles (like monopoles) that, if abundant, would have dominated the universe’s evolution, preventing it from looking as it does. 44:44:00 44:46:00 44:51:00 44:55:00 44:57:00 45:01:00 45:05:00 45:06:00
- Inflation Theory Solution: The theory of inflation was partly developed to “dissolve” these topological defects. If the phase transition that creates them happens before inflation, the universe’s expansion dilutes them sufficiently. 45:11:00 45:15:00 45:20:00 45:23:00 45:30:00 45:32:00
- Experimental Verification: The Kibble-Żurek mechanism allows for calculation and experimental verification of defect density in laboratory settings, such as liquid Helium or quantum computer simulations of phase transitions. 45:34:00 45:37:00 45:41:00 45:44:00 45:48:00 45:51:00 45:53:00 45:54:00 45:58:00 46:00:00 46:03:00 46:06:00 46:09:00 46:15:00 46:17:00 These experiments offer specific predictions and contribute to understanding how matter behaves. 46:19:00 46:21:00 46:22:00 46:25:00 46:27:00 46:31:00 46:33:00 46:35:00 46:36:00 46:40:00 46:45:00 46:50:00 46:54:00 46:56:00 47:00:00 47:03:00 47:06:00 47:09:00 47:13:00
Information and Consciousness
The nature of information itself is a subject of inquiry. 00:26:00 00:28:00 00:31:00
- Information as Secondary: Professor Żurek suggests that information is not a primary category but a secondary one. 22:00:00 22:03:00 22:06:00 22:10:00 22:11:00 22:13:00 22:16:00 22:19:00 22:21:00 22:23:00 Quantum states have the potential to transmit and exist, leading to what we observe. 22:26:00 22:32:00 22:36:00 22:41:00 22:43:00 22:46:00 22:48:00
- Teleportation: Quantum physics includes phenomena like teleportation, which involves the transmission of information over distances, though full object teleportation is deemed unlikely due to the massive amount of classical and quantum information required. 22:51:00 22:53:00 22:55:00 22:58:00 23:01:00 23:02:00 23:05:00 23:08:00 23:10:00 23:12:00 23:16:00 23:19:00 23:22:00 23:24:00 23:28:00 23:30:00 23:32:00 23:35:00 23:37:00 23:38:00 23:43:00 23:48:00 23:51:00 23:56:00 23:59:00 24:00:00
- Consciousness: The question of how consciousness arises from matter is a very interesting, yet unresolved, problem. 30:06:00 30:09:00 30:13:00 30:15:00 It is currently unknown what consciousness is, making it difficult to formulate the question precisely. 31:34:00 31:36:00 31:38:00 31:41:00 31:43:00 31:45:00 31:48:00 31:51:00
Challenges in Quantum Computing
The most groundbreaking area in quantum physics currently involves attempts to build quantum computers. 24:03:00 24:06:00 24:08:00 24:10:00 24:14:00 24:16:00 24:19:00 24:22:00 24:25:00 24:29:00 24:32:00 24:34:00
- Decoherence as a Barrier: The main problem in building quantum computers is decoherence. 24:52:00 24:55:00 For a quantum computer to operate with hundreds of “kits” (qubits), it becomes extremely difficult for the quantum system to survive environmental interference and remain controlled. 24:59:00 25:00:00 25:05:00 25:10:00 25:28:00 25:31:00 25:33:00
- Fundamental Contradiction: Quantum computer components need to interact strongly with each other to perform calculations quickly. However, strong internal interaction makes them highly susceptible to even weak external interactions, which can derail quantum processes. 25:37:00 25:39:00 25:42:00 25:43:00 25:47:00 25:50:00 25:52:00 25:54:00 25:56:00 25:59:00 26:01:00 26:06:00 26:10:00 26:12:00
- Quantum Simulation/Emulation: A more promising approach than direct quantum computing is to simulate or emulate various complex quantum systems using quantum devices. 26:16:00 26:19:00 26:23:00 26:27:00 26:29:00 26:33:00 26:36:00 26:44:00 26:48:00 These efforts are showing promising results and connect quantum mechanics with solid-state physics. 26:51:00 26:53:00 26:55:00 26:58:00 27:07:00 27:12:00
Philosophical Questions and Reflection
Professor Żurek emphasizes that “ignorance condemns a person to originality” 01:05:00 04:06:00 and that wandering, even into blind alleys, is necessary for scientific discovery, provided one recognizes and corrects mistakes. 37:25:00 37:29:00 37:31:00 37:34:00 He defines a “deep truth” (after Bohr) as a statement whose negation is also a deep truth. 28:42:00 28:43:00 28:45:00 28:48:00 28:50:00 28:54:00 28:56:00