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Alex C · @neuralex

65 followers · 244 posts · Server neurodifferent.me

I've been snacking on #physics tutorials (mostly on youtube) for a few years now and I keep finding cases where initially there was a paradox or controversy, but over time it was basically solved, but everyone still thinks or acts like the controversy is still live. "Wave-particle duality" is one (there is no duality: particles are waves, and wavefunction collapse is bonkers, the end) and "Spin isn't spin!" is another...

Back during lockdown when I was watching #PBSSpaceTime and #ScienceAsylum and #Sabine and learning about Stern-Gerlach apparatuses and quantum erasers and such, my explanation of "it acts like it's spinning, but it's not spinning!" (after plenty of pondering) was "well maybe it's spinning through an extra dimension, or it's connected to something that's spinning around it that we can't see, like the EM field"

and my armchair visualization was: picture a spinning top, whose point touches a table, and that table is Flatland: in 3D it's clearly spinning but in 2D it's a point (or at least its point is too small to measure, thank Planck) so you can't see the spin but it's there -- so the classical objection "it's impossible for a point to spin!" evaporates, and our visual-thinker brains have something to work with like the mathemagicians' brains already do

So I was confused that this "new proposal" for quantum spin is new, since anyone could have imagined this at any time since 1928:

```
"“The electron is ordinarily thought of as a particle,” he says. “But in quantum field theory, for every particle, there’s a way of thinking about it as a field.” In particular, the electron can be thought of as an excitation in a quantum field known as the Dirac field, and this field may be what carries the spin of the electron. “There’s a real rotation of energy and charge in the Dirac field,” Sebens says. If this is where the angular momentum resides, the problem of an electron spinning faster than the speed of light vanishes; the region of the field carrying an electron’s spin is far larger than the purportedly pointlike electron itself. So according to Sebens, in a way, Pauli and Lorentz were half-right: there isn’t a spinning particle. There’s a spinning field, and that field is what gives rise to particles."
```
- https://www.scientificamerican.com/article/quantum-particles-arent-spinning-so-where-does-their-spin-come-from/

I'm not claiming that my visualizations are solving any actual physics problems, just that physics communicators are prone to throwing up their hands and saying "nobody can explain it!" when actually, um, really? cause here's an imperfect but useful explanation off the top of my head; maybe if you mathed it out it could make some testable predictions or simplify some theorems, or maybe it's just an analogy, but either way it's not nothing

Are physics profs these days saying "so picture a spinning top (where the electron is the tip/center)" to explain #spin (which is probably wrong but also useful), just like they all still say "picture a basketball on a rubber sheet" to explain #GeneralRelativity (which is definitely wrong, and only arguably useful since it uses gravity to explain gravity)? cause most of the lecturers I see end up repeating "It can't be spin! It's too small to spin!" and shrug at the possibility of useful analogies

[Shut up and calculate!](https://www.nature.com/articles/505153a)

yes, "spin 1/2" is weird but that's fine; picture a car racing along a Möbius strip but we can only see along the finish line; every lap it flips so it needs two laps to get back to the top of the track; now map that track onto the edge of the invisible spinning top

i know, hindsight is 20/20, everything is obvious once you see it, so I'm not *really* confused but still vaguely discomfited

#physics #pbsspacetime #scienceasylum #sabine #spin #generalrelativity

Last updated 1 year ago

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C. R. Collins · @crcollins

470 followers · 4618 posts · Server writing.exchange

Currently addicted to PBS Space Time. I could binge these all day. Can't say I understand all of it, but I am a happy physics and space geek. 😆

#PBSSpaceTime

#pbsspacetime

Last updated 1 year ago

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Jim Donegan ✅ · @jimdonegan

1553 followers · 4638 posts · Server mastodon.scot

Could The #Universe Be Inside A #BlackHole?

https://www.youtube.com/watch?v=jeRgFqbBM5E&ab_channel=PBSSpaceTime

#PBS #SpaceTime #PBSSpaceTime #Astronomy #Astrophysics #Gravity #Singularity #BigBang #Expansion #Inflation #Infinity #GR #GeneralRelativity #Geodesic #Geodesics #EventHorizon #WhiteHole #WhiteHoles #BlackHoles #MattODowd

#mattodowd #blackholes #whiteholes #WhiteHole #eventhorizon #geodesics #geodesic #generalrelativity #gr #infinity #inflation #expansion #bigbang #singularity #gravity #astrophysics #astronomy #pbsspacetime #spacetime #pbs #blackhole #universe

Last updated 1 year ago

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Burak Gürsoy · @burak

55 followers · 104 posts · Server gursoy.social

YouTube - What If The Speed of Light is NOT CONSTANT?

What If The Speed of Light is NOT CONSTANT?

#PBSSpaceTime

https://www.youtube.com/watch?v=Bw8b9YV0EPA

#pbsspacetime

Last updated 1 year ago

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GM7077 · @GM7077

61 followers · 684 posts · Server masto.ai

How Do We Know What #Stars Are Made Of? #pbsspacetime
https://youtu.be/hp2Ek1cA1LE

#stars #pbsspacetime

Last updated 1 year ago

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sean · @ssoper

28 followers · 303 posts · Server noc.social

Ars Technica - NANOGrav hears “hum” of gravitational wave background, louder than expected

just incredible news from the folks at #nanograv who announced that their galaxy-sized detector has revealed the long-theorized background hum of gravitational waves resulting from the likely mergers of supermassive black holes. can't wait to see the #pbsspacetime take on it.

https://arstechnica.com/science/2023/06/nanograv-picks-up-signal-of-cosmic-choir-of-supermassive-black-holes/

#pbsspacetime #nanograv

Last updated 1 year ago

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Jim Donegan ✅ · @jimdonegan

1509 followers · 4428 posts · Server mastodon.scot

What #Supernova Distance Would Trigger A #MassExtinction?

https://www.youtube.com/watch?v=KrRvJUZaswo&ab_channel=PBSSpaceTime

#PBS #SpaceTime #PBSSpaceTime #Astronomy #Astrophysics #Star #Stars #Supernovae #CoreCollapseSupernova #CoreCollapseSupernovae #Betelgeuse #GammaRays #GammaRadiation #MattODowd

#mattodowd #gammaradiation #gammarays #betelgeuse #corecollapsesupernovae #corecollapsesupernova #supernovae #stars #star #astrophysics #astronomy #pbsspacetime #spacetime #pbs #massextinction #supernova

Last updated 1 year ago

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PaJamas · @mooklepticon

15 followers · 185 posts · Server mstdn.social

Open media

Lol #PBSSpaceTime

"aliens yeeting themselves thru the cosmos" https://youtu.be/QMFLcmsjOBg

#pbsspacetime

Last updated 1 year ago

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Jim Donegan ✅ · @jimdonegan

1471 followers · 4180 posts · Server mastodon.scot

Can A #Supermassive #BlackHole Change Direction?

https://www.youtube.com/watch?v=OvPmwVzrI7M&ab_channel=PBSSpaceTime

#PBS #SpaceTime #PBSSpaceTime #Astronomy #Astrophysics #AngularMomentum #Spin #Rotation #Conservation #SupermassiveBlackHole #ParticleBeam #MattODowd

#mattodowd #particlebeam #supermassiveblackhole #conservation #rotation #spin #angularmomentum #astrophysics #astronomy #pbsspacetime #spacetime #pbs #blackhole #supermassive

Last updated 2 years ago

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Xenharmonic Space Raven · @sudoreboot

125 followers · 2744 posts · Server sunbeam.city

YouTube - How Decoherence Splits The Quantum Multiverse

Oops, forgot to add the decoherence part (actual answer to the question advertised).

As you find yourself always in one possible reality -- one fully coherent overall state defining you and all particles entangled with you -- it can be said that all other realities that evolved "in parallel" from a shared point in your history have 'decohered' from yours.

So the answer is: while we don't truly know, there is no reason to think those other realities "went" anywhere; they may be just as real as yours is and exist in parallel, overlapping to various degrees.

Some decohered realities merge back together with yours, and while it isn't proven to be 'the' explanation, you can still observe what the result of such a merging would look like: it would look like a particle behaving like a wave, as demonstrated in the double slit experiment.

#PBSSpacetime did a good video on decoherence, explaining this much better than I could: https://www.youtube.com/watch?v=GlOwJWJWPUs

#pbsspacetime

Last updated 2 years ago

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