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#physics

11 posts11 participants0 posts today
Public
Dr. John Barentine FRAS

JWST just keeps dropping bangers this week.

This image is of a galaxy in a cluster called SMACSJ0028.2-7537. But it's a two-fer, courtesy of general relativity: "What at first appears to be a single, strangely shaped galaxy is actually two galaxies that are separated by a large distance. The closer foreground galaxy sits at the center of the image, while the more distant background galaxy appears to be wrapped around the closer galaxy, forming a ring."

The apparent 'wrapping' of the background spiral galaxy results from the gravity of the foreground elliptical galaxy. It warps the space (and time) around it, changing the paths taken by light from the background object, creating a funhouse mirror effect. In honor of the theorizer of general relativity, these configurations are called 'Einstein rings'.

More info: esawebb.org/images/potm2503a/

📷: ESA/Webb, NASA & CSA, G. Mahler

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.
#Astronomy#Astrophysics#Physics
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Ele Willoughby, PhD

Happy birthday to Wilhem Röntgen (1845-1923), the German physicist who discovered x-rays and earned the Nobel Prize for physics in 1901. I’ve depicted him in this thermochromic portrait at work, studying this mysterious, newly discovered, invisible form of light, based on a photograph of him in his lab, using a Crookes tube to produce x-rays. The form of the print mimics the nature of his discovery -
🧵
#MastoArt #linocut #sciart #Roentgen #physics #histstm #xrays #printmaking

Linocut print of Röntgen in thermochromic indigo ink over his skeleton in white with a blue Crookes tube, table and papers
Public
Mikko Tuomi

Back in 1915, Einstein put forth his most ambitious idea: the general theory of relativity, combining #gravity with #relativity to create an entirely new conception of our #Universe.

In most conventional circumstances, the predictions of Einstein’s theory are indistinguishable from that of its predecessor: Newton’s law of universal gravitation.

Is it possible, then, to somehow reduce Einstein’s equations down to Newton’s equations?

#physics
bigthink.com/starts-with-a-ban

Big ThinkAsk Ethan: Can we turn Einstein's equations into Newton's law?Einstein's General Relativity has reigned supreme as our theory of gravity for over a century. Could we reduce it back down to Newton's law?
Continued thread
Public
Alexander Knochel

This statement is only as useful as it is, because the theorem tells us exactly the formula for the conserved quantity.

You can think of the theorem as a machine which takes the mathematical expression of the fundamental laws as input and churns out a formula for the quantities which don't change over time in the presence of these #physics laws..

Continued thread
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Alexander Knochel

It alludes to the essential insight from the theorem: That *symmetries* in the laws of nature are directly related to so-called *conserved quantities* which cannot be lost or destroyed or created.

Much of our troubles with energy nowadays are due to the fact that energy cannot simply be made to appear, or created anew, it needs to be sourced in one form (i.e. chemical, nuclear,....) and can merely be converted to a useful form.

Now, it turns out that the conserved quantity which we traditionally associate is with "Energy" is just the one which is tied to time translation invariance, i.e. the fact that the laws of nature, formulated in a suitable format, are the same tomorrow as they were yestersay.
/
#physics

Continued thread
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Alexander Knochel

Let me start this way:

I get asked rather often - "what is energy, actually"?

Over the years, I had a variety of different answers which always turned out to be either kind of vague, mysterious at worst, or not very general and unsatisfactory.

Thanks to Noether's theorem, I can instead give the following very precise statement:

There is a conserved quantity which is associated, via the Noether Theorem, with the time translation invariance of the fundamental laws of nature. I call this quantity the Energy.

Let's take this statement apart a bit./
#physics

Public
Alexander Knochel

So today is the birthday of Amalie Emmy Noether.

I cannot speak competently about her work in pure mathematics - in other words, the majority of her ground-breaking accomplishments elude me somewhat.

But as a theoretical physicist, I can speak about her contribution to #physics which is so wonderfully deep yet simple.

So this is a short Thread on Noether's Theorem /

An old bw photograph of youngish Emmy Noether looking to the right, wearing a white blouse and a big bow tie
Public
Ele Willoughby, PhD

Happy birthday Pierre-Simon, marquis de Laplace (23 March 1749 – 5 March 1827), French mathematical physicist (who incidentally, did invaluable work in geophysics). He was pretty hard-headed and probably didn’t really have any imaginary friends, but nonetheless Laplace’s Demon is my 3rd in the series of Imaginary Friends of Science. In 1814, when he envisioned an entity such
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#linocut #printmaking #histsci #MastoArt #Laplace #LaplacesDemon #physics #determinism #ImaginaryFriends #Science

My linocut print of Laplace’s Demon. The demon, who looks like Laplace with giant long-horn cattle horns seated in the lotus position with his palms together as in prayer, is printed in black. Between his horns is space in black with comets, galaxies, stars and planets carved away showing in white. Around him are deep yellow radiating triangles and the words “Laplace’s Demon” following the shape of the horns.
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