Ciro Santilli @cirosantilli  40

Protein folding problem Updated 2025-07-16

Parasites tend to have smaller DNAs Updated 2025-07-16

If you live in the relatively food abundant environment of another cell, then you don't have to be able to digest every single food source in existence, of defend against a wide range of predators.

So because DNA replication is a key limiting factor of bacterial replication time, you just reduce your genome to a minimum.

And likely you also want to be as small as possible to evade the host's immune system.

Power, Sex, Suicide by Nick Lane (2006) section "Gene loss as an evolutionary trajectory" puts it well:

One of the most extreme examples of gene loss is Rickettsia prowazekii, the cause of typhus. [...] Over evolutionary time Rickettsia has lost most of its genes, and now has a mere  protein-coding genes left. [...] Rickettsia is a tiny bacterium, almost as small as a virus, which lives as a parasite inside other cells. It is so well adapted to this lifestyle that it can no longer survive outside its host cells. [...] It was able to lose most of its genes in this way simply because they were not needed: life inside other cells, if you can survive there at all, is a spoonfed existence.

and also section "How to lose the cell wall without dying" page 184 has some related mentions:

While many types of bacteria do lose their cell wall during parts of their life cycle only two groups of prokaryotes have succeeded in losing their cell walls permanently, yet lived to tell the tale. It's interesting to consider the extenuating circumstances that permitted them to do so.
[...]
One group, the Mycoplasma, comprises mostly parasites, many of which live inside other cells. Mycoplasma cells are tiny, with very small genomes. M. genitalium, discovered in 1981, has the smallest known genome of any bacterial cell, encoding fewer than 500 genes. M. genitalium, discovered in 1981, has the smallest known genome of any bacterial cell, encoding fewer than 500 genes. [...] Like Rickettsia, Mycoplasma have lost virtually all the genes required for making nucleotides, amino acids, and so forth.

Homology (biology) Updated 2025-07-16

Fairchild Semiconductor Updated 2025-07-16

Some nice insights at: Robert Noyce: The Man Behind the Microchip by Leslie Berlin (2006).

GlobalFoundries Updated 2025-07-16

AMD just gave up this risky part of the business amidst the fabless boom. Sound like a wise move. They then fell more and more away from the state of the art, and moved into more niche areas.

Infineon Technologies Updated 2025-07-16

SMIC Updated 2025-07-16

SMIC, Explained by Asianometry (2021)

Source.

TSMC Updated 2026-05-27

One of the companies that has fabs, which buys machines from companies such as ASML and puts them together in so called "silicon fabs" to make the chips

As the quintessential fabless fab, there is on thing TSMC can never ever do: sell their own design! It must forever remain a fab-only company, that will never compete with its customers. This is highlighted e.g. at youtu.be/TRZqE6H-dww?t=936 from Video "How Nvidia Won Graphics Cards by Asianometry (2021)".

How Taiwan Created TSMC by Asianometry (2020)

Source. Some points:

UCM failed because it focused too much on the internal market, and was shielded from external competition, so it didn't become world leading
one of TSMC's great advances was the fabless business model approach.
they managed to do large technology transfers from the West to kickstart things off
one of their main victories was investing early in CMOS, before it became huge, and winning that market

Video 2.

The Early Years at TSMC by Asianometry

. Source. 2023.

Arecibo message Updated 2025-07-16

Start codon Updated 2025-07-16

Stop codon Updated 2025-07-16

Amazon Web Services Updated 2025-07-16

Alibaba Cloud Updated 2025-07-16

Google Cloud Platform Updated 2025-07-16

International Organization for Standardization Updated 2025-07-16

Closed access academic journal Updated 2025-07-16

Quartz clock Updated 2025-07-16

How a quartz watch works by Steve Mould (2017)

Source. Mentions feedback loop loop with the quartz tuning fork for the piezoelectricity and an amplifier. Also mentions the choice of 32768 Hertz (

2^{15}

) as the first power of 2 that is outside of the human hearing range, and then how a frequency divider is used to reduce the frequency to get the second counter.

Atomic clock Updated 2025-07-16

How atomic clock works? answer by Ciro Santilli on Physics Stack Exchange.

How an atomic clock works, and its use in the global positioning system (GPS) by EngineerGuy (2012)

Source. Shows how conceptually an atomic clock is based on a feedback loop of two hyperfine structure states of caesium atoms (non-radioactive caesium-133 as clarified by the Wikipedia page). Like a quartz clock, it also relies on the piezoelectricity of quartz, but unlike the quartz clock, the quartz is not shaped like a tuning fork, and has a much larger resonating frequency of about 7 MHz. The feedback is completed by producing photons that resonate at the right frequency to excite the caesium.

Video 2.

Inside the HP 5061A Cesium Clock by CuriousMarc (2020)

Source.

A similar model was used in the Hafele-Keating experiment to test special relativity on two planes flying in opposite directions. Miniaturization was key.

Contains a disposable tube with 6g of Caesium. You boil it, so when it runs out, you change the tube, 40k USD. Their tube is made by Agilent Technologies, so a replacement since that opened in 1999, and the original machine is from the 60s.

Detection is done with an electron multiplier.

youtu.be/eOti3kKWX-c?t=1166 They compare it with their 100 dollar GPS disciplined oscillator, since GPS satellites have atomic clocks in them.

Video 3.

Quick presentation of the atomic clock at the National Physical Laboratory (2010)

Source. Their super accurate setup first does laser cooling on the caesium atoms.

Clifford plus T Updated 2025-07-16

Set of quantum logic gate composed of the Clifford gates plus the Toffoli gate. It forms a set of universal quantum gates.