Ciro Santilli @cirosantilli 37

Initially there were mathematical reasons why people suspected that all boson needed to have 0 mass as is the case for photons a gluons, see Goldstone's theorem.

However, experiments showed that the W boson and the Z boson both has large non-zero masses.

So people started theorizing some hack that would fix up the equations, and they came up with the higgs mechanism.

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High budget movies are shit  Updated 2025-06-17  +Created 1970-01-01

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Movies that are very expensive to make tend to be bad, because they have to make returns and thus appeal to a large amorphous population without any specialization, i.e. the lowest common denominator but in TV Tropes terminology rather than mathematics: tvtropes.org/pmwiki/pmwiki.php/Main/LowestCommonDenominator.

See e.g.:

Looking down the largest flops of all time list didn't help much, only Heaven's gate appears reasonable from the top 20.

On TV Tropes: it's Popular Now It Sucks.

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High-temperature superconductivity  Updated 2025-06-17  +Created 1970-01-01

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As of 2020, basically means "liquid nitrogen temperature", which is much cheaper than liquid helium.

The dream of course being room temperature and pressure superconductor.

Figure 1.
Timeline of superconductivity from 1900 to 2015
. Source.

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History of the Josephson effect  Updated 2025-06-17  +Created 1970-01-01

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In 1962 Brian Josephson published his inaugural paper predicting the effect as Section "Possible new effects in superconductive tunnelling".

In 1963 Philip W. Anderson and John M. Rowell published their paper that first observed the effect as Section "Possible new effects in superconductive tunnelling".

Some golden notes can be found at True Genius: The Life and Science of John Bardeen page 224 and around. Philip W. Anderson commented:

We were all - Josephson, Pippard and myself, as well as various other people who also habitually sat at the Mond tea and participated in the discussions of the next few weeks - very much puzzled by the meaning of the fact that the current depends on the phase

As part of the course Anderson had introduced the concept of broken symmetry in superconductors. Josephson "was fascinated by the idea of broken symmetry, and wondered whether there could be any way of observing it experimentally."

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Magnetic resonance imaging  Updated 2025-06-17  +Created 1970-01-01

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MRI is using NMR to image inside peoples bodies!

Video 1.

How does an MRI machine work? by Science Museum (2019)

Source. The best one can do in 3 minutes perhaps.

Video 2.

How MRI Works Part 1 by thePIRL (2018)

Source.

youtu.be/TQegSF4ZiIQ?t=326 the magnet is normally always on for the entire lifetime of the equipment!
youtu.be/TQegSF4ZiIQ?t=465 usage of non-ionizing radiation (only radio frequencies) means that it is very safe to use. The only dangerous part is the magnetic field interacting with metallic objects.

Video 3.

What happens behind the scenes of an MRI scan? by Strange Parts (2023)

Source.

Video 4.

Dr Mansfield's MRI MEDICAL MARVEL by BBC

. Source. Broadcast in 1978. Description:

Tomorrow's World gave audiences a true world first as Dr Peter Mansfield of the University of Nottingham demonstrated the first full body prototype device for Magnetic resonance imaging (MRI), allowing us to see inside the human body without the use of X-rays.

Featuring the yet-to-be 2003 Nobel Prize in Physiology and Medicine Dr. Mansfield.

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MakeCode Miro Bit  Updated 2025-06-17  +Created 1970-01-01

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makecode.microbit.org

Microbit simulator using some Microsoft framework.

TODO the Python code from there does not seem to run on the microbit via uflash, because it is not MicroPython.

support.microbit.org/support/solutions/articles/19000111744-makecode-python-and-micropython explains.

forum.makecode.com/t/help-understanding-local-build-options/6130 asks how to compile locally and suggests it is possible. Seems to require Yotta, so presumably compiles?

Presumably this is because Microsoft ported their MakeCode thing to the MicroBit, and the Micro Bit foundation accepted them.

E.g. there toggling a LED:

led.toggle(0, 0)

but the code that works locally is a completely differently named API set_pixel:

microbit.display.set_pixel(0, 0, )

Microsoft going all in on adopt extend extinguish from an early age!

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Mark 17 nuclear bomb  Updated 2025-06-17  +Created 1970-01-01

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Mathematician  Updated 2025-06-17  +Created 1970-01-01

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Poet, scientists and warriors all in one? Conquerors of the useless.

A wise teacher from University of São Paulo once told the class Ciro Santilli attended an anecdote about his life:

I used to want to learn Mathematics.
But it was very hard.
So in the end, I became an engineer, and found an engineering solution to the problem, and married a Mathematician instead.

It turned out that, about 10 years later, Ciro ended up following this advice, unwittingly.

Figure 1.
xkcd 435: Fields arranged by purity
. Source.

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Mathieu group  Updated 2025-06-17  +Created 1970-01-01

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Contains the first sporadic groups discovered by far: 11 and 12 in 1861, and 22, 23 and 24 in 1973. And therefore presumably the simplest! The next sporadic ones discovered were the Janko groups, only in 1965!

Each

M_{n}

is a permutation group on

n

elements. There isn't an obvious algorithmic relationship between

n

and the actual group.

TODO initial motivation? Why did Mathieu care about k-transitive groups?

Their; k-transitive group properties seem to be the main characterization, according to Wikipedia:

22 is 3-transitive but not 4-transitive.
four of them (11, 12, 23 and 24) are the only sporadic 4-transitive groups as per the classification of 4-transitive groups (no known simpler proof as of 2021), which sounds like a reasonable characterization. Note that 12 and 25 are also 5 transitive.

Looking at the classification of k-transitive groups we see that the Mathieu groups are the only families of 4 and 5 transitive groups other than symmetric groups and alternating groups. 3-transitive is not as nice, so let's just say it is the stabilizer of

M_{23}

and be done with it.

Video 1.

Mathieu group section of Why Do Sporadic Groups Exist? by Another Roof (2023)

Source. Only discusses Mathieu group but is very good at that.

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Video game console  Updated 2025-06-17  +Created 1970-01-01

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Who needs a hackable general purpose computer, when you can buy a completely locked down computer that only runs useless programs for which you have to pay thousands of dollars to develop for, cannot run a large percentage of major titles from competitor hardware due to business deals (see also) and will inevitably reach planned obsolescence in 4 years?

By company:

Nintendo video game consoles

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XPath  Updated 2025-06-17  +Created 1970-01-01

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XPath kind of died with the rise of CSS selectors around the beginnning of the 2010's. But that is a shame. XPath is a good standard, and was generally more powerful than CSS selectors for many many years.

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Box2D  Updated 2025-06-17  +Created 1970-01-01

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Craig Steven Wright  Updated 2025-06-17  +Created 1970-01-01

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This dude actually managed to convince a brain-dead British court that he was Satoshi and force a takedown of the Bitcoin whitepaper from bitcoin.org/bitcoin.pdf where it had been for many years prior: coinmarketcap.com/academy/article/bitcoin-org-ordered-to-take-down-bitcoin-whitepaper-because-of-copyright-infringement The page was updated to simply display the following Satoshi quote:

It takes advantage of the nature of information being easy to spread but hard to stifle. - Satoshi Nakamoto

The mere thought that Satoshi would attempt to copyright takedown the Bitcoin whitepaper, and not be able to back his identidy with any cryptographic keys, makes one shrivel to the bones.

Also, kids, this is why you put a fucking license on everything you release to the public, and especially when doing so anonymously!!! A quick CC BY-SA on that paper would have prevented all this bullshit.

The existence of this outrageous fraudster has had two good effects on the world however it must be said:

the release of Adam Back and Martti Malmi early email history with Satoshi: www.forbes.com/sites/digital-assets/2024/02/23/new-emails-reveal-staggering-clues-to-the-mystery-of-bitcoin-creator-satoshi-nakamoto
the memes: Craig Steven Wright memes

Timeline:

2015-12-08 Wired article claims he may be Satoshi: www.wired.com/2015/12/bitcoins-creator-satoshi-nakamoto-is-probably-this-unknown-australian-genius/. A few days later, evidence of foul play emerged, and on 2019-04-30 Wired retracted the article altogether
2016-05-02 publicly claims he is Satoshi www.timesofisrael.com/australian-entrepreneur-craig-wright-says-he-created-bitcoin/
2024-05-20 British judge James Mellor fisting the fuck out of Craig: www.reuters.com/technology/self-proclaimed-bitcoin-inventor-lied-repeatedly-support-claim-says-uk-judge-2024-05-20/
An Australian computer scientist who claimed he invented bitcoin lied "extensively and repeatedly" and forged documents "on a grand scale" to support his false claim, a judge at London's High Court ruled on Monday.
Dr Wright presents himself as an extremely clever person. However, in my judgment, he is not nearly as clever as he thinks he is.

Social media:

Interesting

www.reddit.com/r/Bitcoin/comments/4i7k9a/strange_edits_on_craig_wrights_wikipedia_page/ "Strange edits on Craig Wright's Wikipedia page made two days before the revelation, from an IP address in Barbados (possibly made by Craig himself?)"

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f3d  Updated 2025-06-17  +Created 1970-01-01

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github.com/f3d-app/f3d

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Maxwell's equations  Updated 2025-06-17  +Created 1970-01-01

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Unified all previous electro-magnetism theories into one equation.

Explains the propagation of light as a wave, and matches the previously known relationship between the speed of light and electromagnetic constants.

The equations are a limit case of the more complete quantum electrodynamics, and unlike that more general theory account for the quantization of photon.

The equations are a system of partial differential equation.

The system consists of 6 unknown functions that map 4 variables: time t and the x, y and z positions in space, to a real number:

$E_{x} (t, x, y, z)$ , $E_{y} (t, x, y, z)$ , $E_{z} (t, x, y, z)$ : directions of the electric field $E : R^{4} \to R^{3}$
$B_{x} (t, x, y, z)$ , $B_{y} (t, x, y, z)$ , $B_{z} (t, x, y, z)$ : directions of the magnetic field $B : R^{4} \to R^{3}$

and two known input functions:

$ρ : R^{3} t o R$ : density of charges in space
$J : R^{3} \to R^{3}$ : current vector in space. This represents the strength of moving charges in space.

Due to the conservation of charge however, those input functions have the following restriction:

\frac{\partial ρ}{\partial t} + \nabla \cdot J = 0

(1)

Equation 1.

Charge conservation

Also consider the following cases:

if a spherical charge is moving, then this of course means that $ρ$ is changing with time, and at the same time that a current exists
in an ideal infinite cylindrical wire however, we can have constant $ρ$ in the wire, but there can still be a current because those charges are moving
Such infinite cylindrical wire is of course an ideal case, but one which is a good approximation to the huge number of electrons that travel in a actual wire.

The goal of finding

E

and

B

is that those fields allow us to determine the force that gets applied to a charge via the Equation "Lorentz force", and then to find the force we just need to integrate over the entire body.

Finally, now that we have defined all terms involved in the Maxwell equations, let's see the equations: