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Spacetime is a four-dimensional topological manifold with a smooth atlas carrying a torsion-free connection compatible with a Lorentzian metric and a time orientation satisfying the Einstein field equations (EFE).
\[\underbrace{(\mathcal{M},\mathcal{O},\mathcal{A},\nabla,\text{g},\mathcal{T})}_{\text{Relativistic spacetime}}\]
#spacetime #space #time #physics #relativity #generalrelativity #specialrelativity #differentialgeometry #manifold #theoreticalphysics #einstein #lorentz

#Lorentz #einstein #theoreticalphysics #manifold #differentialgeometry #specialrelativity #generalrelativity #relativity #physics #time #space #spacetime

Last updated 2 years ago

Original post

JordiGH · @JordiGH

818 followers · 21351 posts · Server mathstodon.xyz

So in #Lightyear, Buzz reaches a speed of 0.7𝑐 and somehow that turns his four minutes into four years relative to some planet.

Bro, do you even #Lorentz factor?

I hope Disney fired someone for THAT blunder!

#Lorentz #lightyear

Last updated 2 years ago

Original post

Jeroen Hoogstraten ✔️ · @jeroenhoogstraten

230 followers · 648 posts · Server mastodon.online

Open media

Balkon

Op verkenning door de #wetenschapsbuurt in #Schiedam #lorentz

#Lorentz #schiedam #wetenschapsbuurt

Last updated 2 years ago

Original post

Pat · @Pat

125 followers · 2266 posts · Server qoto.org

Follow up on Causality as an emergent phenomenon...

(Ref. to: https://qoto.org/@Pat/106722620334765036)

I found sources on the topic:

Causality – Complexity – Consistency:
Can Space-Time Be Based on Logic and Computation?
https://arxiv.org/pdf/1602.06987.pdf

Causal Emergence in Quantum Mechanics
https://arxiv.org/pdf/1901.07471.pdf

Perfect signaling among three parties
violating predefined causal order
https://arxiv.org/pdf/1312.5916.pdf

Causality theory for closed cone structures with applications
https://arxiv.org/pdf/1709.06494.pdf

Plus an older article, "CPT Violation Implies Violation of Lorentz Invariance" by O.W. Greenberg, which might be related to the topic.
https://arxiv.org/abs/hep-ph/0201258

I just found these yesterday on arXiv and really haven't vetted them much. There's more out there, mostly from the last decade or so. Not sure why I couldn't find this before -- I tried multiple times this year to find this stuff and now a week after I posted here I find a bunch of stuff. Go figure...

Some of it is about non-locality and some also on temporal non-causality like disordered cause/effect. (Some authors use the term acausality instead of non-causality.)

Also, there's a prof at U. Miss. (Luca Bombelli, www.phy.olemiss.edu/~luca/) with some nice reference lists:

Causality in Quantum Field Theory
https://www.phy.olemiss.edu/~luca/Topics/st/causal_qft.html

Causality in Quantum Theory
https://www.phy.olemiss.edu/~luca/Topics/st/causal_qm.html

Causality
https://www.phy.olemiss.edu/~luca/Topics/st/causal.html

Hope this useful.

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#einstein #bohr #causality #spacetime #belltest #epr #paradox #light
#atom #atoms #electron #proton #quark #neutron #electricity #stem #technology
#cern #matter #energy #higgs #particle #lorentz #simultaneity #lightcone
#physics #QM #relativity #gravity #time #space

#einstein #bohr #causality #spacetime #belltest #epr #paradox #light #atom #atoms #electron #proton #quark #neutron #electricity #stem #technology #cern #matter #energy #higgs #particle #Lorentz #simultaneity #lightcone #physics #qm #relativity #gravity #time #space

Last updated 3 years ago

Original post

Pat · @Pat

125 followers · 2266 posts · Server qoto.org

More detail on the non-causality poll...

I'd expect adherents to quantum mechanics to choose "sometimes".

Since QM appears to introduce uncertainty (probabilistic) in place of causality (deterministic) (i.e., it moves from certainty toward randomness), I don't see why a deeper dive couldn't move entirely to randomness (non-causality).

Non-causality appears to be a generalization of nonlocality (or perhaps complimentary to it).

Because of the results of the Bell test experiments, there appears to be renewed interest in explicit theories of nonlocality (e.g., extentions of de Broglie–Bohm theory) to make QM more palatable.

I think the development of a construct for a non-causal extent with causality emergent at macroscopic levels (or emergent at the quantum/macro interface) could serve the same purpose, but I haven't been able to find anything on that.

*** Does anybody know of anyone who is working on that? ***

Here are some more hashtags to cast the net a bit wider. (feel free to comment even after the poll is complete):

#einstein #bohr #causality #spacetime #belltest #epr #paradox #light
#atom #atoms #electron #proton #quark #neutron #electricity #stem #technology
#cern #matter #energy #higgs #particle #lorentz #simultaneity #lightcone
#physics #QM #relativity #gravity #time #space