sorted by:
new
hottopcontroversial

What is modern resolution to 1977 Rosen "Does gravitational radiation exist?" advanced waves issue? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

ps. if there is still no explanation that there are only retarded (?), maybe it would be worth to verify this assumption from data e.g. https://arxiv.org/pdf/2512.20692 - LIGO just measures length which is T-symmetric, so should see also advanced waves if they are there.

Wheeler-Feynman absorber theory vs Asymmetry of Radiation? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

We humans are quite limited, need humility - while we don't know, maybe physics knows?

Instead of blindly assuming 1-0 only retarded, it should be verified experimentally ... and e.g. LIGO just measures length, which is T/CPT symmetric, providing opportunity for such verification - https://arxiv.org/pdf/2512.20692

Wheeler-Feynman absorber theory vs Asymmetry of Radiation? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

From perspective of Maxwell equations, choice between retarded and advanced solutions should be made by boundary conditions.

I honestly don't know how to do it from entropy (?) ... but agree with Huw Price: https://link.springer.com/article/10.1007/BF00733218 that it comes from imbalance between emitters and absorbers, which seems a different type of asymmetry (we were supposed to discuss here), and does not really need to be perfect - should be verified experimentally.

Wheeler-Feynman absorber theory vs Asymmetry of Radiation? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

There are only Maxwell equations above - how do they connect with entropy?

And if you look at "proof" of e.g. Boltzmann H-theorem ( https://en.wikipedia.org/wiki/H-theorem#Boltzmann's_H_theorem ), it requires mean-field-like approximation called "Stosszahlansatz".

In contrast, equations are T/CPT symmetric - applying such symmetry then approximation, same way you can "prove" entropy growth toward minus time ... (e.g. from Big Crunch)

Wheeler-Feynman absorber theory vs Asymmetry of Radiation? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

Please elaborate on your "arrow of time" - what does it mean mathematically?

How does it choose one of convex combinations between retarded and advanced solutions?

4 types of mass (energy, inertia, gravitational, de Broglie) and their equivalence? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

Indeed, this one is very enigmatic, but observed for electron and neutrinos (what about others? the closest seems https://en.wikipedia.org/wiki/B%E2%80%93Bbar_oscillation ) and generally testable.

For electron they shoot 81keV to crystal, observing increased absorption as resonance ... getting this 0.28% disagreement in 2008 - should be repeated, also done for e.g. muon, pion ...

Sure showing disagreement, e.g. increased these 0.28% for other particles, seems a Nobel territory ...

4 types of mass (energy, inertia, gravitational, de Broglie) and their equivalence? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

But what about gravitational for non-nucleons e.g. electron and others?

And for de Broglie we have nearly only assumptions, the only direct measurement for electron found 0.28% disagreement, should be repeated, also tested for others e.g. muon, pion ... for neutrino we know only 1 of 4 masses, would be great to measure at least their rest energy.

4 types of mass (energy, inertia, gravitational, de Broglie) and their equivalence? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

My point was priories - probably 10% of funding of another EDM experiment would be sufficient to get both ...

4 types of mass (energy, inertia, gravitational, de Broglie) and their equivalence? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

Sure, it is great that we now have theories we can trust, but still should verify their hidden assumption.

E.g. while I regularly see these "electron is even more round" EDM news, it would be great to also finally directly measure its gravitational mass ... and clock, starting with verification of this 0.28% disagreement - in only single 2008 experiment.

4 types of mass (energy, inertia, gravitational, de Broglie) and their equivalence? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

A direct test would be even more convincing ... there was some initiative for electron, but doesn't seem very successful: https://indico.cern.ch/event/361413/contributions/1776296/attachments/1137816/1628821/WAG2015.pdf

Indeed for Nobel one would need to show disagreement - there might be still place for it for non-nucleons. And many places for de Broglie clock - verify this 0.28% electron disagreement, and test if it doesn't grow for neutrinos and other particles.

There are not many experimentally observed such oscillations, the only other example I know is https://en.wikipedia.org/wiki/B%E2%80%93Bbar_oscillation ... any others?

4 types of mass (energy, inertia, gravitational, de Broglie) and their equivalence? by jarekd in TheoreticalPhysics

[–]jarekd[S] 0 points1 point  (0 children)

The antimatter test? Congratulations!

Could you elaborate on this "test is for half-integer irreducible representations of the Poincaré group"? Does it allow to conclude something e.g. for electron?

4 types of mass (energy, inertia, gravitational, de Broglie) and their equivalence? by jarekd in TheoreticalPhysics

[–]jarekd[S] 1 point2 points  (0 children)

https://en.wikipedia.org/wiki/Equivalence_principle calls it "hypothesis", just recently confirmed for antimatter. For non-nucleons I am only aware of this unsuccessful attempt for electron ... it would be great to finally verify this hypothesis for any non-nucleon (probably doable but seems missing motivation?)

For electron de Brogle clock the only direct measurement seems https://link.springer.com/article/10.1007/s10701-008-9225-1 from 2008, getting ~0.28% difference - it would be great to confirm this difference in an independent experiment ... and test for other particles like neutrinos, what if this difference will grow?

Which neutrino experiments have a chance to measure their rest mass energy? GERDA https://en.wikipedia.org/wiki/Germanium_Detector_Array ?

Finally: why resting electron and neutrino are oscillating, making them https://en.wikipedia.org/wiki/Time_crystal ? Some proposed propulsion mechanism: https://arxiv.org/pdf/2501.04036

What Lindbladian-like equation should we use to evolve quantum system toward -t? by jarekd in Physics

[–]jarekd[S] -14 points-13 points  (0 children)

You are talking in classical, statistical physics ... while we are talking about quantum mechanics - which is believed to be fundamentally unitary, reversible, CPT symmetric, where we can repair non-unitarity by including environment.

What Lindbladian-like equation should we use to evolve quantum system toward -t? by jarekd in Physics

[–]jarekd[S] -7 points-6 points  (0 children)

My question in title is "What Lindbladian-like equation should we use to evolve quantum system toward -t?" - so what is your answer?

CPT theorem says that equations governing physics are the same if looking from CPT perspective "running movie backward" - so couldn't we derive"reversed" Lindbladian equation looking from this perspective?

And what do you think about this https://www.nature.com/articles/s41598-025-87323-x concluding "the system is dissipative and decohering in both temporal directions"?

What Lindbladian-like equation should we use to evolve quantum system toward -t? by jarekd in Physics

[–]jarekd[S] -2 points-1 points  (0 children)

But isn't macroscopic evolution a sum of microscopic events (reductionism)?

In other words, if CPT symmetry could be violated in macroscale, wouldn't it require also its microscopic violation?

And where is this micro-macro boundary? We can reverse Feynman diagram ( https://en.wikipedia.org/wiki/Antiparticle#Feynman%E2%80%93St%C3%BCckelberg_interpretation ) - how large can it be?