Primordial Black Holes with Elba Alonso-Monsalve and David Kaiser

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Recorded: 2024/07/03 Released: 2024/09/03

Jim talks with Elba Alonso-Monsalve and David Kaiser about the prospects of a class of primordial black holes as a candidate for dark matter. These tiny black holes form just after the inflationary epoch when it is possible for them to form from inhomogeneities wihtout a prior history as a star. Black holes forming during this time time-frame would not have to be color neutral as baryons and mesons are.
------------------------------------------- Notes:

1. The articles that we discussed for this program:

• Alonso-Monsalve, E. and D.I. Kaiser, "Primordial Black Holes with QCD Color Charge." Phys. Rev. Lett. 132 231402 (2024) [arXiv]
• Alonso-Monsalve, E. and D.I. Kaiser, "Debye Screening of Non-Abelian Plasmas in Curved Spacetimes." Phys. Rev. D 108 125010 (2023) [ arXiv ]

2. Other papers and articles mentioned in the podcast:

• De Swart, J., "How Dark Matter Came To Matter." Nature Astronomy 1 0059 (2017) . [ Free

3.Dave's webpage at MIT.

• One of Dave's books I particularly liked: Drawing Theories Apart
• Dave's OCW lectures on YouTube - Einstein, Oppenheimer, Feynman: Physics of the 20th Century.

4. Related Episodes of Physics Frontiers:

• Physics Frontiers 71: Inflation and the Primordial Graviton Background with Sunny Vagnozzi
• Physics Frontiers 69: The Flavor Puzzle with Joe Davighi
• Physics Frontiers 57: Quantum Effects and Gravitational Waves
• Physics Frontiers 51: Gravitational Wave Astronomy
• Physics Frontiers 31: The Parameterized Post-Newtonian Framework
• Physics Frontiers 10: Requirements for Gravitational Theories

5. Please visit and comment on our subreddit, YouTube Channel, or Twitter account. These are also places to look for announcements of new episodes and the like. And if you could help us keep this going by contributing to our Patreon, we'd be grateful.

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Quantum Machine Learning with Bruna Shinohara

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Recorded: 2024/02/16 Released: 2024/05/31

Jim talks with Bruna Shinohara about quantum machine learning.
------------------------------------------- Notes:

1. The article that we discussed in this program:

• Biamonte, J. P. Wittek, N. Pancotti, P. Rebentrost, N. Wiebe, S. Lloyd, "Quantum Machine Learning." Nature 549 195 (2017) [arXiv]
• Wang, Y., "When Quantum Computing Meets Data Science." [ Free ]
• Schuld, M. and N. Killoran, "Is Quantum Advantange the Right Goal for Quantum Machine Learning?." PRX 3 030101 (2022) [ arXiv ]

2. Other papers and articles mentioned in the podcast:

• Aaronson, Scott, "Read the Fine Print." Nature Physics 11 211 (2015). [ Free
• I'll ask Bruna to send me a link to the large QML article she talked about in the podcast.

/ 3. Related Episodes of Physics Frontiers:

• Physics Frontiers 73: Quantum Money with Jiahui Liu
• Physics Frontiers 64: Born's Rule with Blake Stacey

4. Please visit and comment on our subreddit, YouTube Channel, or Twitter account. These are also places to look for announcements of new episodes and the like. And if you could help us keep this going by contributing to our Patreon, we'd be grateful.

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Maxwellian Ratchets with Alex Jurgens

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Recorded: 2023/12/18 Released: 2024/03/31

Jim talks with Alex Jurgens of INRIA about Maxwellian Ratchets. These are abstract machines that react to outside stimuli, These are highly specified theoretical realizations of Maxwell's Demon, who flaunts the second law of thermodynamics. Jurgens discusses these in terms of entropy, information processessing, and the second law.
------------------------------------------- Notes:

1. The article that we discussed in this program:

• Kiefer, Claus, "Functional Thermodynamics of Mawellian Ratchets: Constructing and Deconstructing Patterns, Randomizing and Derandomizing Behaviors." Phys. Rev. Research 2 033334 (2020) [arXiv]

2. Related Episodes of Physics Frontiers:

• Physics Frontiers 74: Maxwellian Ratchets with David Wolpert
• Physics Frontiers 68: Qunatum Resource Theories with Gilad Gour

3. Books mentioned:

• The Road to Maxwell's Demon, Meir Hemmo and Orly R. Shenker. Claus' book on quantum gravity.
4. Please visit and comment on our subreddit, YouTube Channel, or Twitter account. These are also places to look for announcements of new episodes and the like. And if you could help us keep this going by contributing to our Patreon, we'd be grateful.


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Undecidability and Theories of Everything with Claus Kiefer

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Recorded: 2023/08/07 Released: 2024/01/28

Jim talks with Claus Kiefer about his recent essay on the relationship between the Gödel's incompleteness theoerems and the possibility of developing a theory of everything. Incompleteness was originally developed to show that every axiomatic system that is sufficiently robust admits well-formed statements that have a liar's paradox-like structure - if you assume the statement is true, you can prove it's false, and vice-versa. This statement is then said to be undecidable. Undecidability also famously comes up in the halting problem of computer science and the continuum hypothesis. Professor Kiefer speculates here that theories of everything are similarly undecidable.
------------------------------------------- Notes:

1. The article that we discussed in this program:

• Kiefer, Claus, "Gödel's undecidability theorems and the search for a theory of everything" (2023) [arXiv]

2. Other papers referred to in this podcast:

• Cubitt, T.,D. Perez-Garcia and H.M. Wolf, "Undecidability of the Spectral Gap." Nature 528 207 (2015) [arXiv]
• Goedel,, K., "On Formally Undecidable Propositions of Principia Mathematica and Related Systems." Monatshefte für Mathematik und Physik 38 173 (1931) [Free]
• The Undecidable [Amazon], M. Davis, ed. Reprints Goedel's paper and other work from the 1930's. Dover book.

3. Related Episodes of Physics Frontiers:

• Physics Frontiers 69: The Flavor Puzzle with Joe Davighi
• Physics Frontiers 62: Deformed Special Relativity
• Physics Frontiers 45: Loop Quantum Gravity
• Physics Frontiers 35: The String THeory Landscape.

4. Books mentioned:

• Quantum Gravity, 3rd. Ed., Claus Kiefer. Claus' book on quantum gravity.
• The Physical Basis of the Direction of Time, H. Dieter Zeh. Excellent book going over how the arrow of time might be directed via different aspects of physics. Video Review
• The Undecidable [Amazon], M. Davis, ed. Reprints Goedel's paper and other work from the 1930's. Dover book.
• The Character of Physical Law, Richard Feynman
• Road to Reality, Roger Penrose
• Non Standard Analysis, Abraham Robinson or Applied Non-Standard Analysis, Martin Davis. Two books on non-standard analysis. Despite The Undecidable and Applied Non-Standard Analysis being about 6" from each other on my bookshelves for at least a decade, I didn't make the connection that the editor of the first was also the author of the second until this moment.
• Goedel, Escher, Bach, D. Hofstadter.

5. Please visit and comment on our subreddit, YouTube Channel, or Twitter account. These are also places to look for announcements of new episodes and the like. And if you could help us keep this going by contributing to our Patreon, we'd be grateful.

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The Measurement Problem with Nick Ormrod and V. Vilasini

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Recorded: 2023/07/17 Released: 2023/08/20

Jim talks with Nick Ormrod and V. Vilasini about their use of categorical probability theory to study the measurement problem of quantum mechanics. They use the CPT to analyze a no-go theorem to see where there are weaknesses in the underlying structure of quantum mechanics without referring to particular mathematical formualtions of the subject, allowing them to show that the measurement problem comes from difficulties in our understanding of the evolution of quantum states or the way we interpret measurements.
------------------------------------------- Notes:

1. The article that we discussed in this program:

• Ormrod, N., V. Vilasini, and J. Barrett, "Which Theories Have a Measurement Problem?" (2023) [arXiv]

2. Other papers referred to in this podcast:

• N. Ormrod and J. Barrett, "A No-Go Theorem for Absolute Observed Events Without Inequalities or Modal Logic." [arXiv]
• V. Vilasini and M. P. Woods, "A General Framework for Consistent Logical Reasoning in Wigner's Friend Scenarios: Subjective Perspectives of Agents Within a Single Quantum Circuit." [arXiv]
• Maudlin, T., "Three Measurement Problems." Topoi 14 7 (1995).

3. Related Episodes of Physics Frontiers:

• Physics Frontiers 46: Wigner's Friend
• Physics Frontiers 44: Spooky Action at a Distance
• Physics Frontiers 30: The Consistent Histories Interpretation of Quantum Mechanics
• Physics Frontiers 2: The de Broglie-Bohm Interpretation of Quantum Mechanics

4. Please visit and comment on our subreddit, YouTube Channel, or Twitter account. These are also places to look for announcements of new episodes and the like. And if you could help us keep this going by contributing to our Patreon, we'd be grateful.

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Stochastic Thermodynamics with David Wolpert

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Recorded: 2023/05/10 Released: 2023/07/09

Jim talks with David Wolpert about the stochastic thermodynamics of compuation. The discussion focuses on recent developments in the relationship between non-equilibrium processes and information processing, having deep implications on how we view the world and how we apply statistical physics to biological, computational, and other systems.
------------------------------------------- Notes:

1. The articles that we discussed in this program:

• Tasmin, F., N. Fuentes, and D. Wolpert, "The Fundamental Thermodynamic Costs of Communications." (2023) [arXiv]
• Wolpert, D., "Minimal Entropy Production of Interacting Systems." New Journal of Physics 22 113013 (2020) [arXiv]
• Wolpert, D., "The Stochastic Thermodynamcis of Computation." J. Phys. A: Math. Theor. 52 193001 (2019). [arXiv] (Review Article)

2. Other papers referred to in this podcast:

• Landauer, R., "Irreversibility and the Heat Generation in the Computing Process" (IEEE Reprint). IBM J. Res. Dev. 5 283 (1961).[Free] [see 4]
• Bennett, C.H., "Logical Reversibility of Computation." IBM J. Res. Dev. 17 525 (1973). [Free] [see 4]
• Sagawa, T., "Thermodynamic and Logical Reversibilities Revisited." J. Stat. Mech. 2014 P03025 (2014).[arXiv]
• Parrondo, J.M.R/, J. M. Horowitz, and T. Sagawa, "Thermodynamics of Information." Nature Physics 11, 131 (2015).
3. Related Episodes of Physics Frontiers:

• Physics Frontiers 68: Quantum Resource Theories
• Physics Frontiers 16: Stochastic Resonance Energy Harvesting
4. Many of the classic works about the thermodyanmics of information, including many by Landauer and Bennett who are discussed in the episodde, are reprinted in Maxwell's Demon [Amazon], edited by Leff and Rex. Supplementing this with some of the references above would be useful. 5. Please visit and comment on our subreddit, YouTube Channel, or Twitter account. These are also places to look for announcements of new episodes and the like. And if you could help us keep this going by contributing to our Patreon, we'd be grateful.


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Quantum Money with Jiahui Liu

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Recorded: 2023/03/28 Released: 2023/06/18

Jim talks with Jiahui Liu about quantum money. Quantum Money is a key milestone in quantum crytography -- not for the breaking of codes (e.g., Shor's algothrithm), but instead for using quantum computing to improve cryptography beyond what is possible in classical cryptography. The difficulty is, however, a fully satisfactory way to implement quantum money is not currently known. Jiahui discusses both how to show that a possible implementation doesn't work, and how she developed another scheme to implemet quantum money. She also discusses the history of quantum money and some of the things quantum crytographers can do once they have a reliable quantum money scheme.
------------------------------------------- Notes:

1. The articles that we discussed in this program:

• Liu, J., H. Montogomery, and M. Zhandry, "Another Round of Breaking and Making Quantum Money: How to Not Build It from Lattices, and More." in Advances in Cryptography - EUROCRYPT2023 Lecture Notes in Computer Science 14004 611 (2023) [arXiv]

2. Related Episodes of Physics Frontiers:

• Physics Frontiers 64: The Born Rule

3. Please visit and comment on our subreddit, YouTube Channel, or Twitter account. These are also places to look for announcements of new episodes and the like. And if you could help us keep this going by contributing to our Patreon, we'd be grateful.

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