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Mr.Trunk · @mrtrunk
10 followers · 18024 posts · Server dromedary.seedoubleyou.me
Gizmodo - Perplexing Pulsar ‘Switching’ Behavior Finally Deciphered by Astronomers

#northamericannanohertzobservatoryforgravitationalwaves #gravitationalwaveastronomy #mariacristinabaglio #technologyinternet #gravitationalwave #generalrelativity #millisecondpulsar #radioastronomy #cotizelati #startypes #pulsar

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1563 followers · 4708 posts · Server mastodon.scot
YouTube - Juan Maldacena - Does Information Create the Cosmos?

#RobertKuhn #CloserToTruth #HolographicPrinciple #holography #generalrelativity #gr #relativity #quantumgravity #gravity #universe #entanglement #wavefunction #superposition #quantumphysics #physics #quantummechanics #qm #cosmology #PhilosophyOfCosmology #science #philosophyofscience #philosophy #cosmos #information #juanmaldacena

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1560 followers · 4691 posts · Server mastodon.scot

#RobertKuhn #CloserToTruth #multiverse #generalrelativity #gravity #topology #flatnessproblem #monopoles #magneticmonopoles #alanguth #guth #standardmodel #inflation #cosmology #PhilosophyOfCosmology #science #philosophyofscience #philosophy #universe #briankeating

Last updated 1 year ago
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Alex C · @neuralex
65 followers · 244 posts · Server neurodifferent.me

I've been snacking on 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 and and 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."
```
- scientificamerican.com/article

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 (which is probably wrong but also useful), just like they all still say "picture a basketball on a rubber sheet" to explain (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!](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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Alex Nelson · @thmprover
21 followers · 47 posts · Server mathstodon.xyz

Teitelboim's PhD thesis (and a few subsequent articles) discusses how the surface deformation algebra and "ultralocality" allows us to derive the matter part of the Hamiltonian and Momenta constraints. Teitelboim worked through the Scalar, Vector, and (covariant rank-2) Tensor cases.

Surprisingly enough, it works also for Spin-1/2 fields! We find
\[\delta\psi\sim-\int\{\psi,\mathcal{H}_{i}^{\text{Dirac}}(y)\}\,\delta N^{i}(y)\,\mathrm{d}y\]
where
\[\mathcal{H}_{i}^{\text{Dirac}}\sim \pi\partial_{i}\psi +\frac{1}{8}\pi\partial^{j}(\gamma_{i}\gamma_{j}-\gamma_{j}\gamma_{i})\psi\]
possibly up to an additional term like the second with derivatives acting to the right. This generates the Lie derivative of the Dirac spin-1/2 field
\[\delta\psi = \mathcal{L}_{\delta N}\psi = (\partial_{i}\psi)\delta N^{i} - \frac{1}{8}(\partial_{i}(\delta N_{j}) - \partial_{j}(\delta N_{i}))\gamma^{i}\gamma^{j}\psi.\]
(At least, if I've done my calculations correctly...)

But that's amazing!

#diracfield #algebraofsurfacedeformations #generalrelativity

Last updated 1 year ago
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Sarcasmic · @opethminded
181 followers · 2718 posts · Server mstdn.social

There, I fixed it for you.

A singularity-free force of gravitation:

F=G(m1+m2)/(r+ ℓP)^2

G = universal gravitational constant
m1 = mass of object 1
m2 = mass of object 2
r = the distance b/w the objdcts
ℓP = Planck length

When do I get my Nobel?

#yourewelcome #gravity #generalrelativity #Physics

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1558 followers · 4681 posts · Server mastodon.scot
YouTube - Did Time Really Move Slower in the Past?

#drbenmiles #quasars #quasar #bigbang #infinity #eventhorizon #gravity #TimeDilation #frameofreference #referenceframe #generalrelativity #gr #philosophyoftime #philosophyofscience #philosophy #time #benmiles

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1557 followers · 4678 posts · Server mastodon.scot

#perimiterinstitute #entanglement #blackholes #loopquantumgravity #quantumgravity #QuantumFieldTheory #quantummechanics #qm #generalrelativity #gr #time #space #PhilosophyOfCosmology #cosmology #philosophyofscience #philosophy #physics #science #universe #spacetime #meaning #lecture #juanmaldacena

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1557 followers · 4676 posts · Server mastodon.scot

#davidkipping #coolworldslab #causality #weakenergycondition #wec #gr #generalrelativity #specialrelativity #miguelalcubierre #Alcubierre #spacetime #gravity #propulsion #astronautics #engineering #warpbubble #warpdrive #science #physics #drive #warp #coolworlds

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1557 followers · 4653 posts · Server mastodon.scot

#RobertKuhn #CloserToTruth #stringtheory #gravitationalwaves #time #space #generalrelativity #gr #energy #mass #relativity #astrphysics #expansion #cosmology #PhilosophyOfCosmology #physics #science #philosophyofscience #philosophy #spacetime #juanmaldacena

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1553 followers · 4638 posts · Server mastodon.scot

#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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Jim Donegan ✅ · @jimdonegan
1553 followers · 4634 posts · Server mastodon.scot

#shadow #doppler #optics #gravitationallensing #gravitationallens #lens #AccretionDisk #warpedspace #warpedspacetime #spacetime #gravity #generalrelativity #gr #physics #astrophysics #science #nicklucid #scienceasylum #blackholes

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1548 followers · 4613 posts · Server mastodon.scot

@ninokadic

Absolutely. You don't see him very much on but his contributions are always great. Plus I always like to see philosophers bigging up rather than the constant stream of stuff you get from many.

#quantum #generalrelativity #CloserToTruth

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1546 followers · 4605 posts · Server mastodon.scot

#RobertKuhn #CloserToTruth #generalrelativity #gr #BlockUniverse #asymmetry #freewill #freedom #causation #determinism #spacetime #lawsofphysics #lawsofnature #laws #entropy #timesarrow #now #present #past #future #science #philosophyofscience #philosophyoftime #philosophy #time #real #robinlepoidevin

Last updated 1 year ago
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Jim Donegan ✅ · @jimdonegan
1538 followers · 4582 posts · Server mastodon.scot
YouTube - The Mysterious Theory That Could Change Everything We Know: How Constants of Nature Could Vary

#gr #generalrelativity #relativity #jwst #standardmodel #cdm #lcdm #λcdm #cosmos #universe #astrophysics #astronomy #physics #cosmology #science #PhilosophyOfCosmology #philosophyofscience #philosophy #nasaspacenews #constant #constants

Last updated 1 year ago
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MPI for Gravitational Physics · @mpi_grav
407 followers · 535 posts · Server social.mpdl.mpg.de
Open media

Balzan PhD and Postdoc positions in “Historical and philosophical aspects of solving the two-body problem in General Relativity” offered by @mpi_grav Potsdam, the Lichtenberg Group for History and Philosophy of Physics at the University of Bonn, and the Max Planck Research Group “Final Theory Program” at the Max Planck Institute for History of Science.

ℹ️ aei.mpg.de/1048741/balzan-phd-

#phd #postdoc #generalrelativity #historyofscience

Last updated 1 year ago
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Alexander Rogge · @alexanderrogge
42 followers · 1690 posts · Server brighteon.social
Scientists use Exotic Stars to Tune into Hum from Cosmic Symphony

#gravitationalwaves #PulsarTiming #Pulsars #RadioEmissions #Timekeeping #generalrelativity #relativity #BlackHoleBinaries #blackholes #NANOGrav #CollaborativeResearch #CosmicOrchestra #music #astrophysics #cosmology #RadioAstronomy #astronomy

Last updated 1 year ago
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Alexander Rogge · @alexanderrogge
42 followers · 1690 posts · Server brighteon.social
Time appeared to move 5 times more slowly in 1st billion years after Big Bang, quasar 'clocks' reveal

Keith Cooper - Time appeared to move 5 times more slowly in 1st billion years after Big Bang, quasar 'clocks' reveal:

space.com/quasar-clocks-univer

#TimeDilation #Timekeeping #time #blackholes #QuasarClock #clock #Quasars #Redshift #generalrelativity #relativity #astrophysics #cosmology

Last updated 1 year ago
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MPI for Gravitational Physics · @mpi_grav
395 followers · 523 posts · Server social.mpdl.mpg.de
Open media

Balzan PhD and Postdoc positions in “Historical and philosophical aspects of solving the two-body problem in General Relativity” offered by @mpi_grav Potsdam, the Lichtenberg Group for History and Philosophy of Physics at the University of Bonn, and the Max Planck Research Group “Final Theory Program” at the Max Planck Institute for History of Science.

ℹ️ aei.mpg.de/1048741/balzan-phd-

#phd #postdoc #generalrelativity #historyofscience

Last updated 1 year ago
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Ansgar Schmidt :verified: · @Ansi
513 followers · 1627 posts · Server mastodon.cloud

#NancyGraceRomanSpaceTelescope #acceleratingexpansion #generalrelativity #cosmicexpansion #nancygraceroman #euclidmission #darkenergy #cosmology #featured #gravity #nasa

Last updated 1 year ago
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