In celebration of 10k followers, here is a new edition of "people you should follow, but that (given their follower count) probably you don't".
i.e. people I follow, with <5k followers, non-locked, active, that in my personal opinion you should follow too.
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In random order: @LCademartiriLab food, chemistry, architecture, and beauty in general. Trigger warning: strong opinions. @VKValev bit of history of Physics + chiral media @DrBrianPatton social justice in science @alisonmartin57 weaving and bamboo structures
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@schrodingerskit my personal window on a part of humanity that I rarely have occasion to interact with @JamesBSumner University politics (and history) @jelena3121 rankings, and why they are BS @joelacarpenter very cool optics-related videos
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Hope you check them out and find someone cool to follow 🙂
7/7
Bonus: people with already a ton of followers, but that imho should have two tons of followers: @thienan496 Mathematics and visualizations @katherineschof8 Music and the Orient @Yara_Haridy Bones, bones, and more bones @GinaGoesOutside who knew reptiles could be cute?
8/7
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#PhysicsFactlet (299)
Fractional derivatives: a brief tutorial/🧵. If you know some calculus you should be able to follow. If you are a Mathematician (or you like to see things done properly) I advise "Fractional Differential Equations" by I. Podlubny instead 😉
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The history of fractional derivatives begins together with the history of the much more common integer-order derivatives, and a number of big names in mathematics worked on it over the centuries.
Afaik, the first to work on the problem was Leibniz himself.
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Since differentiating twice a function yields the second derivative, the Marquis de l'Hôpital immediately wondered whether it makes sense to think about an operator which, if applied twice, gave the first derivative, i.e. some sort of derivative of order 0.5
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#PhysicsFactlet (283)
Lorentz transformations pre-date Special Relativity. How is that even possible?
A thread.
Trigger warning for typos (hopefully just in the text and not in the equations) and carefree manipulations of equations 😉
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The historical route is interesting but complicated, so I will leave that story for someone more qualified to write it. What I want to look at is: how do we get the Lorentz transformations without knowing anything about special relativity?
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A requirement we want all physical theories to satisfy is the "principle of relativity", i.e. the fact that the laws of Physics are the same in every frame of reference. Were this not the case, each of us would experience a different universe, making life quite complicated.
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#PhysicsFactlet (273)
A brief introduction to the calculus of variations.
Trigger warning: lots of formulas manipulated the way experimental physicists do 🙂
🧵 1/
The simplest introduction to the calculus of variations is to solve in a slightly roundabout way a very easy geometrical problem: what is the shortest path between 2 points on a plane?
(spoiler: it's a straight line)
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Let's pretend we have no idea, and so we are forced to take into consideration all possible functions passing through 2 given points. What we want to do is to calculate the length of each of them, and select the shortest one.
(spoiler: we are not REALLY going to do that) 3/
A few days ago I was asked by some last year students advice on how to decide whether doing a PhD is the right thing to do. I will put here a summary of what I told them, just in case it can be useful for someone else.
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[Disclaimer: What follows are personal opinions based on STEM disciplines in Europe. So this is a partial and (by definition) incomplete picture.
Also, I am assuming you like the subject you want to do a PhD in, and that you can find a supervisor who is not a sociopath.]
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During a PhD you will tackle one or more problems/questions that no one has a answer for. This is dramatically different from what you have ever done at Uni, where all problems had a solution somewhere.
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I am experimenting with recording lectures for the coming term.
Here I will make a summary of how it went in (semi)real-time. Wish me luck 😰
First experiment was (as expected) a disaster.
What was supposed to be a 10min video was over 20min long, with me mumbling, mispronouncing half of the words, and in general being too worried about recording to remember to explain anything. 😭
I was definitively optimistic on how much stuff I can fit in 10 minutes. Will need to rethink how I cut the lectures into videos.
Moving all the old Physics factlects to the same hashtag to make easier to find them. As Twitter does not allow me to edit my tweets, I need to repost all of them. Apologies if this floods your timeline.
#Physicsfactlet (1)
The uncertainty principle is not a principle, it is a theorem. Just like the Pauli exclusion principle and many others. It was a principle when it was first formulated, but we have since realised that it can be derived from first principles.
#Physicsfactlet (2)
There is nothing quantum in describing particles as waves. In fact one can rewrite the whole Newtonian mechanics as a wave theory without changing any result or prediction. (See Hamilton-Jacobi formalism)