Causality, Time and the Experiment Paradox

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Recorded: 2022/03/21 Released: 2022/05/22

Jim talks to Michal Eckstein of the Coperincus Center for Interdisciplinary Studies on how two different ways to order events, that of chronology (this comes before that) and causality (this makes that happen) come together to define time. We then go on to discuss the Experiment Paradox, which pulls together a number of measurement paradoxes in physics.
------------------------------------------- Notes:

1. Michal Eckstein's articles we discussed in this program:

• Eckstein, M. and M. Heller, "Causality and Time Order -- Relativistic and Probabilistic Aspects." (2022) [arXiv]
• Eckstein, M. and P. Horodecki, “The Experiment Paradox in Physics.” Foundations of Science 27, 1 (2020). [arXiv]
• Eckstein, M., P. Horodecki, R. Horodecki, and T. Miller, "Operational Causality in Spacetime" Phys. Rev. A 101 042128 (2020). [arXiv]

2. Michal Eckstein's articles that we discussed in this program:

• Ehlers, J., F.A.E. Pirani, A. Schild, “The Geometry of Free Fall and Light Propagation [2012 Republication].” General Relativity: Papers in Honour of J. L. Synge, 63. (1972).
• Linnemann, N. and J. Read, "Constructive Axiomatics in Spacetime Physics Part I: Walkthrough to the Ehlers-Pirani-Schild Axiomatisation" (2021). [arXiv]
• Minguzzi, E. and M. Sanchez, "The Causal Heirarchy of Space Times." Recent Developments in Pseudo-Riemannian Geometry, 299 (2008). [arXiv]

3. Related Episodes of Physics Frontiers:

• Physics Frontiers 62: Deformed Special Relativity.
• Physics Frontiers 46: Wigner's Friend
• Physics Frontiers 45: Loop Quantum Gravity
• Physics Frontiers 44: Spooky Action at a Distance
• Physics Frontiers 38: Why Is Space-Time Four Dimensional?
• Physics Frontiers 33: Retrocausality
• Physics Frontiers 30: The Consistent Hisotories Interpretation of Quantum Mechanics
• Physics Frontiers 27: The Gravitational Equivalence Principles
• Physics Frontiers 17: The Physics of Time Travel
• Physics Frontiers 12: A Gravitational Arrow of Time
• Physics Frontiers 9: f(R) Theories of 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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Born's Rule

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Recorded: 2022/01/18 Released: 2022/04/24

Jim discusses Gleason's Theorem with Blake C. Stacey of the University of Massachuesetts - Boston. Gleason's Theorem is a theorem in the foundations of quantum mechanics that, for a system meets some simple requirements, you can find a set of valid staes and a rule for calculating probailities, a la the Born Rule. This is the first part of the interview, the next will be on Blake's discussion of how people are trying to reformulate the Born Rule.
------------------------------------------- Notes:

1. Papers we both read for this program:

• Stacey, B., "On Two Recent Approaches to the Born Rule." (2021) [arXiv]
• L. Masanes, T. D. Galley and M. P. Müller, “The Measurement Postulates of Quantum Mechanics Are Operationally Redundant.” Nature Communications 10, 1361 (2019). [arXiv]
• Hossenfelder, S., "Gleason-Type Derivations of the Quantum Probability Rule for Generalized Measurements" Found. Phys. 34 193 (2004). [arXiv]

2. This series:

• Physics Frontiers 63: Gleason's Theorem.
• Physics Frontiers 64: Whence Born's Rule?
• Physics Frontiers 64a: The SICs [Subscribers only until 5/27/2022]
3. Blake Stacey's Book:
Blake Stacey has written a book A First Course in the Sporatic SICs [Amazon]. This book details the use of the strange numbers that Blake and others are using to integrate learning from quantum information theory into quantum foundations. C'mon, it has a section entitled "Quantum Theory from Nonclassical Probability Meshing" -- you have to have it!
4. Related Episodes of Physics Frontiers:

• Physics Frontiers 46: Wigner's Friend
• Physics Frontiers 44: Spooky Action at a Distance
• Physics Frontiers 13: Exotic Photon Trajectories in Quantum Mechanics
5. Please visit and comment on our subreddit, YouTube Channel and if you can help us keep this going by contributing to our Patreon, we'd be grateful.


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Gleason's Theorem

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Recorded: 2022/01/18 Released: 2022/03/20

Jim discusses Gleason's Theorem with Blake C. Stacey of the University of Massachuesetts - Boston. Gleason's Theorem is a theorem in the foundations of quantum mechanics that, for a system meets some simple requirements, you can find a set of valid staes and a rule for calculating probailities, a la the Born Rule. This is the first part of the interview, the next will be on Blake's discussion of how people are trying to reformulate the Born Rule.
------------------------------------------- Notes:

1. Papers we both read for this program:

• Gleason, A.M., "Measures on the Closed Subspaces of a Hilbert Space." Indiana Univ. Math. J. 6, 855 (1957). [arXiv]
• Stacey, B., "On Two Recent Approaches to the Born Rule." (2021) [arXiv]
• Busch, P., "Quantum States and Generalized Observables: A Simple Proof of Gleason’s Theorem." Phys. Rev. Lett. 91, 120403 (2003) [arXiv]
• Hossenfelder, S., "Gleason-Type Derivations of the Quantum Probability Rule for Generalized Measurements" Found. Phys. 34 193 (2004). [arXiv]

2. Other papers one or the other of us read:

• Cabello, A. "Interpretations of Quantum Theory: A Map of Madness." What is Quantum Information?, 38 (2017). [arXiv]

3. Books mentioned in the discussion:

• David W. Cohen, An Introduction to Hilbert Space and Quantum Mechanics[Amazon] The book I found in a college book store in the 1990's. Short, written for mathemtics undergraduate students (at the upper division, high-end SLAC level), but also accessible to philosophy and physics students who can read math. Video review here.
• John von Neumann, Mathematical Foundations of Quantum Mechanics[Amazon] A classic text that started a lot of this quantum philosophy nonsense in the first place. Very difficult read.
• Michaal Neilson and Isaac Chuang, Quantum Computation and Quantum Information.[Amazon] An early, well known book on quantum information. This is one of three technical books that I've had to replace because my original copy wandered off with a graduate student to postdocs unknown.
• John Bell, Speakable and Unspeakable in Quantum Mechanics. [Amazon]
This is a collection of essays by John Bell, some of which are very important, and others of which you might not think are important until you start reading the philosophy of physics literature. Blake mentioned two papers that I think are in this volume. One is "On the Einstein-Poldosky-Rosen Paradox," which was originally published in the small jounal below.

4. Physics-Physique-Fisika, the journal Blake Stacey mentioned in our discussion.

5. Related Episodes of Physics Frontiers:

• Physics Frontiers 46: Wigner's Friend
• Physics Frontiers 44: Spooky Action at a Distance

6. Please visit and comment on our subreddit, YouTube Channel and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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Deformed Special Relativity

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Recorded: 2021/08/08 Released: 2022/02/13

Randy and Jim discuss first order corrections to special relativity in light of quantum gravity: deformed special relativity. What should happen to space time if a minimum length scale is introduced to special relativity?
------------------------------------------- Notes:

1. Papers we both read for this program:

• Amelino-Camelia, G., L. Friedel, J. Kowalski-Gikman, and L. Smolin, "The Principle of Relative Locality." Phys Rev. D 84, 084010 (2011). [arXiv]
• Hossenfelder, S., "The Box Problem in Deformed Special Relativity." (2009) [arXiv]
• Smolin, L., "Classical Paradoxes of Locality and Their Resolution in Deformed Special Relativity." Gen Relativ Gravit, 3671 (2011) [arXiv]
• Hossenfelder, S., "Comments on Nonlocality in Deformed Special Relativity" Phys Rev D 95> 084034 (2010). [arXiv]

2. Other papers one or the other of us read:

• Hossenfelder, S. "Minimal Length Scale Scenarios for Quantum Gravity." Living Reviews in Relativity 16, 2 (2013) [arXiv]
• R. Schtzhold, W. G. Unruh, "Large-Scale Non-Locality in ”Doubly Special Relativity” with an Energy-Dependent Speed of Light." JETP Lett. 78, 431 (2003). [arXiv]

3. Related Episodes of Physics Frontiers:

• Physics Frontiers 57: Quantum Effects in Gravitational Waves
• Physics Frontiers 45: Loop Quantum Gravity
• Physics Frontiers 42: Entropic Gravity
• Physics Frontiers 38: Why is Space-Time Four Dimensional?
• Physics Frontiers 30:The Consistent Histories Interpretation of Quantum Mechanics

4. Randy's obituary and my Patreon post on his death. 5. Please visit and comment on our subreddit, YouTube Channel and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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< a href = https://physicsfm-frontiers.blogspot.com/2022/03/gleasons-theorem.html>( Gleason's Theorem ) Next →

Dark Stars

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Recorded: 2021/06/10 Released: 2021/10/31

Randy and Jim discuss various proposals for objects that mimic black holes. Most of these are based on physics that disallows an infinitely dense point at the center of the black hole, such as string theory or loop quantum gravity, and some include very exotic matter.
------------------------------------------- Notes:

1. Papers we both read for this program:

• Nikitin, I., "On Dark Stars, Planck Cores, and the Nature of Dark Matter ." BLED Proc. 23rd Wkshp. 1, 221 (2021) [arXiv]
• Visser, M., C. Barcelo, S. Liberati, and S. Sonego, "ISmall, Dark and Heavy: But Is It a Black Hole?." PoS BHs, GRandStrings 2008, 105009 (2008) [arXiv]
• Holdom, B. and J. Ren, "Not Quite a Black Hole." Phys Rev D 95> 084034 (2017). [arXiv]

2. Other papers one or the other of us read:

• Nikitin, I. "RDM-Stars and Galactic Rotation Curves." 2021 J. Phys. Conf. Series (2021) [arXiv]

3. Related Episodes of Physics Frontiers:

• Physics Frontiers 57: Quantum Effects in Gravitational Waves
• Physics Frontiers 51: Gracitational Wave Astronomy
• Physics Frontiers 45: Loop Quantum Gravity
• Physics Frontiers 25: Gravitational Field Propulsion
• Physics Frontiers 7: Virtual Gravitational Dipoles

4. Please visit and comment on our subreddit, YouTube Channel and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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Warp Bubbles

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Recorded: 2021/03/25 Released: 2021/09/12

Randy tells Jim about solutions in general relativity that allow for isolated bubbles of spacetime that could, possibly, travel faster than light.
------------------------------------------- Notes:

1. Papers we both read for this program:

• Lobo, F.S.N. and M. Visser, "Fundamental Limitations on "Warp Drive" Spacetimes." Clas. Quant. Grav. 5871 21, (2004) [arXiv]
• Bobrick, A. and G. Maitre, "Introducing Physical Warp Drives." Clas. Quant. Grav. 38, 105009 (2021) [arXiv]

2. Other papers one or the other of us read:

• Lentz, E. " Breaking the Warp Barrier: Hyper-Fast Solitons in Einstein-Maxwell-Plasma Theory ." Clas. Quant. Grav. 38 075015 (2021) [arXiv]
• Carmona, A., J.C. Ruiz, and, M. Neubert "A Warped Scalar Portal to Fermionic Dark Matter." Eur. Phys. J. C 81, 58 (2021) [arXiv]

3. Related Episodes of Physics Frontiers:

• Physics Frontiers 47: Bumetric Gravity
• Physics Frontiers 39: Negative Effective Mass
• Physics Frontiers 31: The Parameterized Post-Newtonian Framework
• Physics Frontiers 25: Gravitational Field Propulsion
• Physics Frontiers 7: Virtual Gravitational Dipoles

Physics Frontiers 6: General Relativity for the Experimentalist

4. Please visit and comment on our subreddit, YouTube Channel and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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The Hubble Crisis

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Recorded: 2021/01/07 Released: 2021/07/05

Randy and Jim the differences between measurements in the Hubble constant and some proposals to resolve the issue.
------------------------------------------- Notes:

1. The papers we read for this program:

• Addison, G.E>, D.J. Watts, C.L. Bennett, M. Halpern, and G. Hinshaw, "Elucidating ΛCDM: Impact of Baryon Acoustic Oscillation Measurements on the Hubble Constant Discrepancy." ApJ 853, 119 (2018) [arXiv]
• Agrawal, P., F.-Y. Cyr-Racine, D. Pinner, L. Randall "Rock'n'Roll Solutions to the Hubble Tension." (2019) [arXiv]
• ..., "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo ." ApJ 909, 208 (2021). [arXiv]
• Carnegie Supernova Project, " The Carnegie Supernova Project: Absolute Calibration and the Hubble Constant ." ApJ 869 56 (2018) [arXiv]
• Yang, T. S. Birrer, and B. Hu, "The first simultaneous measurement of Hubble constant and post-Newtonian parameter from time-delay strong lensing." Mon. Notices Royal Astron. Soc. 497, L56 (2020) [arXiv]

2. Related Episodes of Physics Frontiers:

• Physics Frontiers 56: Multiversality
• Physics Frontiers 35: The String Theory Landscape
• Physics Frontiers 31: The Parameterized Post-Newtonian Framework
• Physics Frontiers 9: f(R) Theories of Gravity

3. Wendy Freedman recently published this article about the same topic, which some people say resolves the tension (It came out in the arXiv in June, we recorded in January, so it wasn't included). After going through it this weekend (7/17-18), I don't think it makes as strong a conclusion as the press made out, but it is worth reading, even at 48 pages. 4. Please visit and comment on our subreddit, YouTube Channel and if you can help us keep this going by contributing to our Patreon, we'd be grateful.

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