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#generalrelativity

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Joe Heafner

[2504.01675] Einstein's elevator and the principle of equivalence arxiv.org/abs/2504.01675

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arXiv.orgEinstein's elevator and the principle of equivalenceWe outlines here the design, execution, and educational outcomes of an intervention inspired by Einstein's elevator thought experiment, intended to introduce secondary school students to the principle of equivalence, which is at the basis of the theory of General Relativity. We build an experimental version of Einstein's elevator, which simulated the effects of free-fall in an accelerated reference frame: a detailed description of the experimental apparatus and its construction is provided, highlighting the challenges and innovations in creating a simple yet functional setup using everyday materials.
#ITeachPhysics#GeneralRelativity
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CosmicRami

Whooooaaaa! The new #JWST image is so good! So much physics going on — physics Einstein himself thought about!

This is called an Einstein Ring. When a massive foreground galaxy (in this case, an elliptical galaxy) warps the space-time around it, light from behind it bends in our direction.

The JWST caught this fantastic example, where the background spiral galaxy is getting warped into our view. It appears as a ring, but we can see its structures like its spiral arms, gas features and star clusters.

Incredible science happening here!

📸 ESA/Webb/NASA/CSA/G. Mahler

I added the annotations in the second image.

In the centre is an elliptical galaxy, seen as an oval-shaped glow around a small bright core. Around this is wrapped a broad band of light, appearing like a spiral galaxy stretched and warped into a ring, with bright blue lines drawn through it where the spiral arms have been stretched into circles. A few distant objects are visible around the ring on a black background.
In the centre is an elliptical galaxy, seen as an oval-shaped glow around a small bright core. Around this is wrapped a broad band of light, appearing like a spiral galaxy stretched and warped into a ring, with bright blue lines drawn through it where the spiral arms have been stretched into circles. A few distant objects are visible around the ring on a black background. The image has been annotated to point out the foreground galaxy as well as the background spiral.
#astronomy#astrophysics#generalrelativity
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rexi

phys.org/news/2025-03-gravity-

…quantifies the difference between the metric of #spacetime and the metric induced by #matter fields.

…modified Einstein equations that, in the low coupling regime, i.e., low energies and small curvature, reduce to the classical equations of #generalrelativity…predicting the emergence of a small, positive cosmological constant—a value that aligns with experimental observations of the universe's accelerated expansion…

Phys.org · Gravity from entropy: A radical new approach to unifying quantum mechanics and general relativityBy Queen Mary, University of London
#quantumgravity#quantuminformation
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