j_bertolotti

j_bertolotti, 11 months ago to random

It is very likely that most of the Physics (and the Mathematical formalism we use to describe it) we give for granted today will be obsolete one day.
And that is why I think it is important to always teach Physics with an eye to what are the experimental evidences that lead people to come up with certain explanations. If we don't we are just teaching people how to be good at a very weird "glass beads game", not how to be scientists.
#ITeachPhysics

j_bertolotti, 11 months ago to random

As much as I love the work of the admins of Mathstodon, is there any instance focussed on optics and/or low energy Physics?
@johnmdudley @sylvaingigan @mickeykats etc etc

oblomov, 11 months ago to random

I think I might have boosted 600 toots just this morning.

Also I hate myself for this because @Tusky can't be configured to hide own boosts in your lists and timelines 8- P

j_bertolotti, 11 months ago to random

I always thought of bees as eusocial animals, but I just discovered that there are a ton of species of solitary bees. And now I feel lied to 😑
#bees

eniko, 11 months ago to random

Very angry to learn that zero times infinity is not zero. Things like this is why I can't respect mathematics

Sardonicus, 11 months ago to random

'Completed in 1998, Maison Bordeaux sits on a small cape-like hill overlooking Bordeaux.
Designed for a couple and their family, but before Koolhaas and OMA were commissioned for the project in 1994 the husband of the family was in a life threatening car accident that left him paralyzed from the waist down.
Despite this the man wanted a complex design, stating: “Contrary to what you would expect. I want a complex house because the house will define my world.”'
https://www.archdaily.com/104724/ad-classics-maison-bordeaux-oma

ColinTheMathmo, 11 months ago to random

Every mathematical proof is a one liner if you start far enough to the left -- Anon

eniko, 11 months ago to random

Can't relate to people who say bluesky is so much better than mastodon. Bluesky feels dead to me. Also one of the arguments I saw was that they had search and algorithms instead of hashtags, and this individual didn't wanna use hashtags

The thing about hashtags is that it makes discoverability opt-in. You decide if you want random word searching bastards to find your posts, which is important since 95% this is done by people looking to harass others

Anyway I wanna wish people luck on bluesky. They're not even out of private beta yet and the people in charge are already talking to press about their plans to add "monetizable value add"

I'm gonna stay here where I can control when I want everyone to be able to find what I say, and where a corporation won't try and carve chunks of functionality out to sell them back to me, a process that inevitably culminates in what happened to twitter and reddit when they can't squeeze enough blood from the stone anymore

christianp, 11 months ago to random

Loads of new people on mathstodon lately. Is this all @samjshah's doing, or is something else going on?

eniko, 11 months ago to random

Going to call everyone trans because calling them cis is a slur

j_bertolotti, 11 months ago to physics

#PhysicsFactlet
Magnetic hysteresis: In a ferromagnet the equilibrium configuration is with all magnetic moments aligned with each other. If we want to flip them, we need to flip all of them at the same time, which requires a stronger field than if the moments were independent, resulting in the characteristic hysteresis loop.

(Simulation done by numerically solve the Landau–Lifshitz equation with a tiny bit of noise added to speed the process up on a square grid of magnetic moment with periodic boundary conditions.)

#Physics #Visualization #ITeachPhysics #Magnetism

Left: a square gray plan with a grid of short lines coming out of it. Each line represents a magnetic moment, and moves following the Landau–Lifshitz equation. An arrow on the left shows the external magnetic field, which starts from up and gradually decrease to zero and then goes negative. The lines representing the magnetic moments move only a little bit until the field is negative and strong, and then start precessing quickly, until they all flip in the new equilibrium configuration. Right: Plot of the total magnetization as a function of the external magnetic field, showing the characteristic hysteresis loop.

j_bertolotti, 11 months ago to random

Technical jargon is a weird beast, so it happens frequently that a word that has a very well defined dictionary meaning is taken by a sub-community and used to mean something completely different (e.g. a "group" in Mathematics does not mean "a number of people or things that are located, gathered, or classed together").
That is fine. But please, don't expect people from outside your sub-field to understand what you are talking about, and don't act surprised when they are utterly confused by your words.

ColinTheMathmo, 11 months ago to random

deleted_by_author

j_bertolotti, 1 year ago to random

Has anybody already made those aperiodic tiles into either fridge magnets or puzzles?

j_bertolotti, 1 year ago to random

#PhysicsFactlet
"Anderson localization" is a weird phenomenon that is not well known even among Physicists, but has the habit of popping up essentially everywhere.
So here is an introductory thread 🧵

The idea of "localization" originally came about as an explanation (by P.W. Anderson, hence the name) of why the spins in certain materials did not relax as fast as expected. What Anderson realized was that when you have a wave (in this case a quantum mechanical wavefunction) that propagates in a random system, interference can play a major role, and potentially impede propagation completely.
The original paper (and, frankly, most of the literature on the subject) is pretty impenetrable, but thankfully Anderson localization can happen any time we have a wave and a random medium, doesn't matter what kind of wave, so we can try to look at a simple system.

Let's start VERY simple with the simple pendulum, and let's make it even simpler by assuming the oscillations are small, and thus we only have to deal with an harmonic oscillator. The pendulum has a natural frequency (i.e. the frequency at which it will naturally oscillate if you just let it go), which will depend on its length and the gravity acceleration pulling it down: ω₀= √(g/L). If you take a bunch of such pendula, they will all oscillate with the same natural frequency.
Let's complicate the problem a bit and add a (elastic) coupling between the pendula. The system in its entirety now will have a number of natural frequencies equal to the number of pendula, resulting in a complex motion that is the superposition of the oscillations at all those different frequencies.
1/

Animation of 10 identical pendula and their natural frequency of oscillation. At the beginning of the animation the pendula are oscillating independently, and thus their natural frequency is the same, but after a short while springs are added, and the natural frequency splits into 10 frequencies.

mcnees, 1 year ago to random

The Gnomes books by Poortvliet and Huygens are beautiful source books for a gentle rpg that exists only in my head.

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