Physics Frontiers

Episode 79: Primordial Black Holes with QCD Color Charge with Elba Alonso-Monsalve and David Kaiser Sep 04, 2024

Jim talks with Elba Alonso-Monsalve and David Kaiser about the prospects to describe dark matter as tiny black holes that were created at the end of cosmic inflation. Due to the large inhomogeneities in the distribution of matter at that time, the black holes could form directly from the matter distribution and not be color neutral (in the sense of QCD).
Show notes: http://frontiers.physicsfm.com/79

Episode 78: Quantum Machine Learning with Bruna Shinohara May 31, 2024

Jim talks with Bruna Shinohara of CMC Microsystems. Quantum computing and machine learning are both currently making huge strides. So it is not strange that people are trying to use quantum computing for machine learning.

Episode 77: Maxwellian Ratchets with Alex Jurgens Mar 31, 2024

Jim talks with Alex Jurgens about Maxwellian ratchets, automata that are similar to Maxwell's Demon. They talk about their implications for information processing and entropy.
http://frontiers.physicsfm.com/77

Episode 76: Undeciability and Theories of Everything with Claus Kiefer Jan 29, 2024

Jim talks with Claus Kiefer about the implications of Goedel's incompleteness theorems on the search for the theory.
Show Notes: http://frontiers.physicsfm.com/76

Episode 75: Categorical Probability and the Measurement Problem Aug 20, 2023

Jim talks with Nick Ormrod and V. Vilasini about their use of categorical probability theory to analyze the measurement problem. We discuss categorical probability theory, which allows them to abstract from particular mathematical formulations of quantum mechanics to more general ideas about states and measurements and observers than found in Hilbert space formulations. They use this to look at the various properties of quantum mechanics and how they relate to each other, in particular how relativity affects the measurement problem.
Show Notes: http://frontiers.physicsfm.com/75

Episode 74: Stochastic Thermodynamics with David Wolpert Jul 09, 2023

Jim talks with David Wolpert about the non-equilibrium behavior of computation, what it means for entropy, and how it relates to traditional thermodynamics.
Show Notes: http://frontiers.physicsfm.com/74

Episode 73: Quantum Money with Jiahui Liu Jun 18, 2023

Jim discusses quantum money with Jiahui Liu. Quantum money is a linchpin of quantum cryptography. The ability to create secure banknotes using quantum computers would allow even more secure methods of encryption for communications.

Episode 72: Born Rule and Gravity with Antony Valentini Apr 23, 2023

Jim talks with Antony Valentini about the difficulties of interpretation of quantum mechanics in light of quantum gravity. In particular, Antony discusses the failure of the Born Rule due to the impossibility of normalization (the fact that probabilities must sum to 100%) at that scale, and therefore the need to interpret the wavefunction as something more than merely the knowledge of the observer about the system. They spend some time talking about the de Broglie-Bohm interpretation in light of quantum gravity.
Show Notes: http://frontiers.physicsfm.com/72

Episode 71: Primordial Graviton Background Feb 19, 2023

Jim talks with Sunny Vagnozzi about using the Primoridial Graviton Background to rule out all inflation models.
Show Notes: http://frontiers.physicsfm.com/71

Episode 70: Path Integrals and Entanglement with Ken Wharton Dec 18, 2022

Jim talks with Ken Wharton about how to describe entangled states as sums over histories of particle paths using the path integral method. He shows how this works for Bell-type experiments, entanglements swapping, delayed choice experiments, and the triangle network. This leads to a second way to describe what happens quantum mechanically without introducing non-locality (but requiring other classical ideas to break down).
Show Notes: http://frontiers.physicsfm.com/70

Episode 69: The Flavor Puzzle with Joe Davighi Nov 20, 2022

Jim talks with Joe Davighi of the University of Zurich about the flavor unification at high energies - the merging of all leptons into one kind of particle. The discussion includes symmetries in particle physics, symmetry breaking at low temperatures, and unification schemes in general. Joe also discusses both leptoquarks and proton stability in the context of his theory.

Episode 68: Quantum Resource Theories with Gilad Gour Sep 26, 2022

Jim talks with Gilad Gour of the University of Toronto about quantum resource theories. These are theories of largish systems that describe the relationships between possible states by the different levels of resources required for each. By using resources, a system can move from one state to another. This results in a partial order where between two states there could be two different states inaccessible to one another. Although (usually) these coalesce into an order based on a single property of thermodynamically-sized systems, the entropy, a few do not.
Show Notes: http://frontiers.physicsfm.com/68

Episode 67: Optical Gravity with Matthew R. Edwards Aug 14, 2022

Jim talks with Matthew R. Edwards about his theory of Optical Gravity. This is a Le Sage model of gravity based on graviton filiments.
Show Notes: http://frontiers.physicsfm.com/67

Episode 66: The Limit of General Relativity with James Owen Weatherall Jun 26, 2022

Jim talks with James Owen Weatherall about his work on viewing general relativity as an effective field theory and where it should give way to another theory. General relativity does a very good job of describing the world we see in astronomical observations, but certain results, e.g. singularities, and certain limits, e.g. the Planck scale, hint that there should be another theory that supersedes it. Jim Weatherall argues that this is in a high curvature regime.
Show Notes: http://frontiers.physicsfm.com/66

Episode 65: Causality, Time and the Experiment Paradox with Michal Eckstein May 22, 2022

Jim talks with Michal Eckstein of the Copernicus Institute for Interdisciplinary Studies about how two different kinds of ordering, chronological and causal, give rise to a robust idea of time. Additionally, we discuss the Experiment Paradox, a generalization of other measurement-type paradoxes in physics.
Show Notes: http://frontiers.physicsfm.com/65

Episode 64: Born's Rule with Blake Stacey Apr 24, 2022

Jim talks with Blake Stacey about recent attempts to replace Born's rule. Born's rule is the principle used in quantum mechanics that associates quantum states to the probability of measurement. There has been a recent interest in Quantum Foundations to try to find a less arbitrary rationale for this procedure.
Show Notes: http://frontiers.physicsfm.com/64

Episode 63: Gleason's Theorem with Blake Stacey Mar 20, 2022

Jim talks with Blake Stacey about Gleason's Theorem, a foundational topic in the foundations of quantum mechanics. Gleason's theorem gives us a set of characteristic states for a measurement and the probability rule associated measuring them. This is the first part of the interview. The second part will discuss recent attempts to replace the Born Rule.
Show Notes: http://frontiers.physicsfm.com/63

Episode 62: Deformed Special Relativity Feb 13, 2022

Jim and Randy talk about how special relativity might be amended to incorporate a minimum length scale. Such scales are common in quantum gravity theories, and in the limit where both QM and GR are less important, QG should induce first order corrections to SR. We then talk about how these corrections seem to lead to unreasonable paradoxes.
Show Notes: http://frontiers.physicsfm.com/62

Episode 61: Dark Stars Oct 31, 2021

Jim and Randy talk about alternatives to black holes without event horizons or singularities.
Show Notes: http://frontiers.physicsfm.com/61

Episode 60: Warp Bubbles Sep 12, 2021

Randy tells Jim about developments of metrics describing isolated spacetime bubbles that could, possibly, move faster than light.
Show Notes: http://frontiers.physicsfm.com/60

Episode 59: The Hubble Crisis Jul 05, 2021

Randy and Jim discuss the current tension between measurements of the Hubble constant by different methods, and some attempts to resolve the issue.
Show Notes: http://frontiers.physicsfm.com/59

Episode 58: Phantom Matter Jun 06, 2021

Jim and Randy talk about the Higgs portal to dark matter and the nightmare scenario for particle physicists: what if the LHC never saw any traces of supersymmetric particles?
Show Notes: http://frontiers.physicsfm.com/58

Episode 57: Quantum Effects in Gravitational Waves May 02, 2021

Randy and Jim talk about two proposals to use gravitational wave interferometry to show that gravitons exist through noise measurements.
Show Notes: http://frontiers.physicsfm.com/57

Episode 56: Anomalous Magnetic Moment of the Muon Apr 01, 2021

Jim and Randy discuss the measurements of the anomalous magnetic moment of the muon and some of the ways in which the discrepancy between theory and experiment could manifest themselves in new physics.
Show Notes: http://frontiers.physicsfm.com/56

Episode 55: Multiversality Dec 07, 2020

Jim and Randy discuss the rationales for multiverses based on quantum mechanics, string theory, and the anthropic principle.
Show Notes: http://frontiers.physicsfm.com/55

Episode 54: The ANITA Experiment Oct 18, 2020

Randy and Jim talk about the strange results of the ANITA experiment: tau neutrinos that seem to come up out of the Earth.
Notes: http://frontiers.physicsfm.com/54

Electromagnetic Gravitational Repulsion Aug 17, 2020

Randy tells Jim about ways in which electromagnetism reduces the gravitational attraction caused by a body.

Sterile Neutrinos Jul 08, 2020

Jim and Randy discuss the hypothesis of sterile neutrinos, neutrinos that are even more ghostly than neutrinos that are dark matter candidates.

Gravitational Wave Astronomy Jun 10, 2020

Jim and Randy talk about gravitational waves.

X17 May 03, 2020

Jim and Randy discuss a possible "fifth force," the hypothetical X17 particle that has been seen in several experiments.
Erratum: The g-2 of the muon was shown to be off by 1 part in 500,000 in 2001 at Brookhaven. It may not be in there, I'm not sure how much of that I cut out.
Show Notes: http://frontiers.physicsfm.com/50

The Unruh Effect Apr 04, 2020

Jim and Randy discuss the apparent creation of quanta seen by comparing the viewpoints of relatively accelerating observers -- the Unruh Effect.
(There is a little noise that shows up on Randy's track half way through - I did my best)
Show Notes: http://frontiers.physicsfm.com/49
(links to papers, podcasts, and more!)

The Gertsenshtein Effect Jan 19, 2020

Randy introduces Jim to the Gertsenshtein effect, the conversion of gravitational waves to electromagnetic waves through resonances.
Show Notes: http://frontiers.physicsfm.com/48

Bimetric Gravity Nov 24, 2019

Randy introduces Jim to Sabine Hossenfelder's bimetric theory of gravity. In this gravitational theory, there are two types of matter whose only interaction is through gravitation. However, each one reacts to space-time differently, resulting in different metric tensors for each. In low-curvature situations, this creates a kind of anti-gravitation.
Show Notes: http://frontiers.physicsfm.com/47

Wigner's Friend Sep 22, 2019

Randy and Jim discuss experiments that purport to show that there is no such thing as objective reality.
Show Notes: http://frontiers.physicsfm.com/46

Loop Quantum Gravity Aug 16, 2019

Jim and Randy discuss loop quantum gravity, and integration of quantum mechanics and gravity that quantizes space-time itself through the use of uncertain quanta of volumes and the random connections between them.

Spooky Action at a Distance Jul 16, 2019

Jim and Randy discuss experiments that put a minimum superluminal speed of communication between parts of a wavefunction.
Show Notes: http://frontiers.physicsfm.com/44

The Positive Energy Theorem Jun 06, 2019

Randy introduces Jim to a refutation of the positive energy theorem in a universe with a cosmological constant.
Show Notes: http://frontiers.physicsfm.com/43

Entropic Gravity May 04, 2019

Jim and Randy discuss Eric Verlinde's theory thermodynamic theory of gravity. This theory purports to explain gravitational attraction and inertia through statistical mechanics.
Show Notes: http://frontiers.physicsfm.com/42

The Chameleon Field Feb 24, 2019

Randy and Jim discuss the chameleon field -- a way to model dark energy with a scalar boson of varying strength.
Show Notes: http://frontiers.physicsfm.com/41

The Octonions Dec 23, 2018

Randy tells Jim about a way to use an extension of an extension of the complex numbers to reveal the nature of elementary particles.
Show Notes: http://frontiers.physicsfm.com/40

Negative Effective Mass Dec 09, 2018

Randy tells Jim about experiments with Neutrons and Photons in materials that exhibit negative effective mass. Not only do these effects show that the inertial mass of quasiparticles in a material can become negative, they show that these negative mass quasiparticles act like they have negative gravitational mass, as well.
Show Notes: http://frontiers.physicsfm.com/39

The Dimensionality of Space-Time Nov 25, 2018

Jim discusses why the world we observe is 4-dimensional with Randy. We discuss anthropic and fundamental reasons why we need 3 dimensions and no more than one time dimension for reasons of complexity, predictability and stability.
Show Notes: http://frontiers.physicsfm.com/38

The Einstein-Cartan Torsion Field Theory Oct 30, 2018

Randy explains to Jim theories on how to incorporate a native angular momentum into general relativity.
Show Notes: http://frontiers.physicsfm.com/37

The Metamaterial Stress Tensor Oct 15, 2018

Randy tells Jim about recent results in the description of the electromagnetic stress tensor in metamaterials. In particular, we discuss the efforts to computationally model the stress tensor in amorphous metamaterials.
Show Notes: http://frontiers.physicsfm.com/36

The String Theory Landscape Sep 22, 2018

Jim and Randy explore the landscape of string theory in the anthropic manner put forward by Leonard Susskind.
Show Notes:
http:frontiers.physicsfm.com/35

CPT Symmetry and Gravitation Aug 10, 2018

CPT Symmetry is a fundamental symmetry in the standard model. Jim and Randy discuss what happens when it is applied to general relativity.
Show Notes: frontiers.physicsfm.com/34
[Really sorry for the muted tracks on the first upload. The problem has been fixed. - J]

Retrocausality Jul 25, 2018

Jim and Randy look at how quantum mechanics is affected by time. Most importantly, what happens when temporal boundary conditions are used to create standing waves in the wave function of a particle?
Show Notes: http://frontiers.physicsfm.com/33

Tunneling Time Jul 07, 2018

Jim talks to Randy about the amount of time it takes for an electron to tunnel through a forbidden region of space. Astoundingly, how quickly this happens has been a subject of debate for eighty years and is still unresolved.
Show Notes: http://frontiers.physicsfm.com/32

Post-Newtonian Gravitation Jun 08, 2018

Jim discusses the Parameterized Post-Newtonian formalism with Randy. The PPN framework is a general, linearized metric theory of gravity that can simulate all metric theories of gravity and compare them to solar system sized experiments.
Show Notes: http://frontiers.physicsfm.com/31

The Consistent Histories Interpretation of Quantum Mechanics May 24, 2018

Jim and Randy discuss the consistent histories interpretation of quantum mechanics. The brainchild of Robert Griffiths and with a surprisingly strong set of supporters, Consistent Histories seems to be a strong, logical description of what happens in the quantum world.
Show Notes: http://frontiers.physicsfm.com/30

Gravitational Alternatives to Dark Energy May 16, 2018

Jim and Randy discuss how modifications to general relativity can be used to mimic the effects of dark energy. They discuss various forms of gravitational theory that can do the job, as well as the field particles that mediate their "fifth force."
Show Notes: http://frontiers.physicsfm.com/29

The Quantum Vacuum and the Casimir Effect Apr 25, 2018

Jim and Randy review two very convincing papers that make the claim that the Casimir effect is due to materials fluctuations and not the zero point energy.
Show Notes: http://frontiers.physicsfm.com/28

The Gravitational Equivalence Principles Apr 15, 2018

Jim talks to Randy about the different ways in which the equivalence principle of general relativity can be formulated. More than just the equivalence of accelerations, the different possible meanings of the equivalence principle mean different things about how gravity works. From weak to strong, from Einstein's equivalence principle to Schiff's conjecture, the implications of these theories are explored.
Show Notes: http://frontiers.physicsfm.com/27

Antimatter Production at a Potential Boundary Mar 25, 2018

Randy shows Jim an idea for generating antimatter using the Casimir effect that doesn't require a collider.
Show Notes: http://frontiers.physicsfm.com/26

Gravitational Field Propulsion Mar 16, 2018

Randy introduces Jim to several ways in which people have theorized that gravity can be used to propel an object through space. The slingshot effect is the only proven method here, but people have found many ways that theoretically could induce propulsion taking advantage of non-commutative motions in space-time, negative inertia, artificially-induced gravitational dipoles, and creating bubbles in space-time.
Show Notes: http://frontiers.physicsfm.com/25

The Island of Stability Feb 24, 2018

Randy tells Jim about the island of stability: a theoretically predicted oasis of stable nuclear isotopes that researchers keep getting nearer and nearer to discovering. Randy and Jim talk about what they are, how researchers are trying to produce the isotopes, and the theoretical methods that predict their existence.
Show Notes: http://frontiers.physicsfm.com/24

Dark Energy Feb 09, 2018

Randy helps Jim get a handle on Dark Energy. Why do we need it? What could it be? What does it have to do with you? How close are we to knowing anything about it?
Show Notes: http://frontiers.physicsfm.com/23

Weyl and Quasiparticles Jan 22, 2018

Jim and Randy discuss quasiparticles recently found in condensed matter systems that mirror particles theorized nearly a hundred years ago, but never found in the vacuum. Weyl particles are massless fermions, and once it was hoped that neutrinos would turn out to be this kind of particle, and Majorana fermions have real-valued wave functions and therefore many strange and possibly useful properties.
Show Notes: http://frontiers.physicsfm.com/22

The Origin of Inertia Jan 11, 2018

Randy tells Jim about a scheme that uses Mach's Principle - the idea that there is a preferred background frame with respect to the fixed stars - to explain the origin of inertia.
Show Notes: http://frontiers.physicsfm.com/21

Time Crystals Dec 22, 2017

Jim talks to Randy about structures that are periodic in time like crystals are periodic in space.
Show notes: http://frontiers.physicsfm.com/20

The 2T Physics of Itzhak Bars Dec 06, 2017

Randy tells Jim about a theory that complements other theories of fundamental physics based upon a phase space symmetry between the 4-position and the 4-momentum of a particle. The upshot of the theory is that there should be a second time dimension and a fourth space dimension, both macroscopic in extent, and the physics we see are 4D projections from the larger 6D space-time.
Show notes: http://frontiers.physicsfm.com/18

The Physics of Time Travel Nov 24, 2017

Randy and Jim talk about traveling through through time, discussing relativity and, in particular, Kurt Goedel's solution for closed timelike curves in General Relativity.
Show notes: http://frontiers.physicsfm.com/17

Stochastic Resonance Energy Harvesting Nov 06, 2017

Randy tells Jim about ways in which external vibrations can be used to do useful work in large-scale devices. These processes look at have happens when bistable systems (e.g., a bent cantilever) are subjected to random forcing from the environment.
Show notes: http://frontiers.physicsfm.com/16

Five Proven Methods of Levitation Oct 21, 2017

Randy shows Jim five different ways in which a body can be levitated: by magnetism, by superconductors, by Lenz' Law, by acoustics, and most recently by thermophoresis.
Show notes: http://frontiers.physicsfm.com/15

Stochastic Electrodynamics Oct 04, 2017

Randy explains Stochastic Electrodynamics to Jim, the theory that vacuum fluctuations are the cause of quantum mechanical behavior.
Show notes: http://frontiers.physicsfm.com/14

Exotic Photon Trajectories in Quantum Mechanics Sep 14, 2017

Jim and Randy discuss strange trajectories observed in triple slit experiments with metallic plates. Photons seem to pass through one slit, come back through the middle slit, and out the third due to their interactions with surface plasmons. There are implications in this experiment about the way in which wavefunctions need to be interpreted in non-relativistic quantum mechanics.
Show notes: http://frontiers.physicsfm.com/13

A Gravitational Arrow of Time Aug 20, 2017

Jim and Randy discuss a cosmological theory that purports to find an explanation for the arrow of time in gravitational theory based on the shape and distribution of matter and how it evolves.
Show notes: http://frontiers.physicsfm.com/12

Photonic Molecules and Optical Circuits Jul 16, 2017

Randy tells Jim about photonic molecules, pairs of photons that create bound states like molecules do through a force mediated through an ultracold gas and similar ideas in optical circuits. They also discuss application of the same for quantum computing.
Show notes: http://frontiers.physicsfm.com/11

Requirements for Alternative Gravity Theories Jul 01, 2017

In this episode Jim and Randy talk about how to evaluate alternative gravity theories. What sort of things do we want them to explain, what experiments do they have to predict, and what theoretical requirements do they have to meet. This is in some ways a continuation of Episode 9 - f(R) Theories of Gravity, but the discussion is relevant to all attempts to amend gravitational theory.
Show notes: http://frontiers.physicsfm.com/10

In the program, Randy talks about the outline I sent him. I put that up on the Physics Frontiers Blog.

f(R) Theories of Gravity Jun 02, 2017

Jim and Randy discuss gravitational theories that modify general relativity by changing the action using a polynomial dependence on the Ricci scalar. Although not physically motivated, some of these theories produce effects similar to those of dark matter, dark energy, and cosmological constants.
Show notes: http://frontiers.physicsfm.com/9

Vacuum Fluctuations and the Casimir Effect Apr 27, 2017

Jim and Randy discuss how vacuum fluctuations produce the van der Waals forces and the Casimir effect. Van der Waals forces are factors in atomic bonds and the Casimir effect produces an attractive force between nanoscale objects. The claim is that vacuum fluctuations -- the production and annihilation of particle-antiparticle pairs -- are the underlying reason for both effects.
Show notes: http://frontiers.physicsfm.com/8

Virtual Gravitational Dipoles Mar 14, 2017

Randy discusses what the Cosmological implications of a negative gravitational mass would be with Jim. If there were a negative gravitational mass (as opposed to inertial mass), then every time that an electron-positron pair was created in the vacuum, that would create a gravitational dipole. This in turn would create effects similar to dark matter, dark energy, and a cosmological constant -- and this in turn would have an effect on the origin of the universe.
Show notes: http://frontiers.physicsfm.com/7

General Relativity for the Experimentalist Feb 14, 2017

Randy shares some of his favorite papers with Jim: papers on general relativity by engineer and science fiction author Robert L. Forward on how general relativity could be used in a terrestrial environment, including proposals for devices and materials. These papers are "General Relativity for the Experimentalist" and "Guidelines to Antigravity."
Show notes: http://frontiers.physicsfm.com/6

Pilot Wave Hydrodynamics Jan 20, 2017

Randy and Jim discuss a physical analogy to quantum mechanics consisting of a droplet of fluid bouncing off of the waves in a similarly composed fluid that were generated by the droplet's own bounces. The analogy is very close to the de Broglie-Bohm interpretation of quantum mechanics.
Show notes: http://frontiers.physicsfm.com/5

Phononics Jan 05, 2017

Randy tells Jim about the emerging field of Phononics: using quantum particles of heat in materials for information processing in advanced materials.
Show notes: http://frontiers.physicsfm.com/4

Gravitoelectromagnetism Dec 06, 2016

Randy talks to Jim about gravitoelectromagnetism. Based on the similarity between Newtonian gravity and electrostatics, there should be a second gravitational field,the gravitomagnetic field. What are the implications of the existence of such a field, and how large are those effects?
Show notes: http://frontiers.physicsfm.com/3

The de Broglie-Bohm Interpretation of Quantum Mechanics Nov 15, 2016

Jim talks to Randy about the pilot wave interpretation of quantum mechanics, which separates the particle and wave behavior of a non-relativistic quantum particle into that of a particle moving in and exciting a quantum mechanical medium.
Show notes: http://frontiers.physicsfm.com/2

G4V: Four Vector Potential Gravitation Oct 31, 2016

Randy talks to Jim about Carver Mead's G4V, a formulation of gravitation combining the equivalence of inertial and gravitational mass with a vector potential formulation of gravitation (a 4-vector form, with the usual gravitational potential in the temporal component).

Show notes: http://frontiers.physicsfm.com/1

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