Ciro Santilli @cirosantilli 34

Condensed matter physics is one of the best examples of emergence. We start with a bunch of small elements which we understand fully at the required level (atoms, electrons, quantum mechanics) but then there are complex properties that show up when we put a bunch of them together.

Includes fun things like:

As of 2020, this is the other "fundamental branch of physics" besides to particle physics/nuclear physics.

Condensed matter is basically chemistry but without reactions: you study a fixed state of matter, not a reaction in which compositions change with time.

Just like in chemistry, you end up getting some very well defined substance properties due to the incredibly large number of atoms.

Just like chemistry, the ultimate goal is to do de-novo computational chemistry to predict those properties.

And just like chemistry, what we can actually is actually very limited in part due to the exponential nature of quantum mechanics.

Also since chemistry involves reactions, chemistry puts a huge focus on liquids and solutions, which is the simplest state of matter to do reactions in.

Condensed matter however can put a lot more emphasis on solids than chemistry, notably because solids are what we generally want in end products, no one likes stuff leaking right?

But it also studies liquids, e.g. notably superfluidity.

One thing condensed matter is particularly obsessed with is the fascinating phenomena of phase transition.

The first diodes. These were apparently incredibly unreliable, especially for portable radios, as you had to randomly search for the best contact point you could find in a random polycrystalline material!!

And also quality was highly dependant on where the material was sourced from as that affected the impurities present in the material. Later this was understood to be an issue of doping.

It was so unreliable that vacuum tube diodes overtook them in many applications, even though crystal detectors are actually semiconductor diodes, which eventually won over!

For a long time, before artificial semiconductors kicked in, people just didn't know the underlying physical working principle of these detectors. What I cannot create, I do not understand basically.

Most notable example: gallium arsenide, see also: gallium arsenide vs silicon.

An important class of semiconductors, e.g. there is a dedicated III-V lab at: École Polytechnique: www.3-5lab.fr/contactus.php

Amazing talk by Richard Feynman that describes his experiences at Los Alamos National Laboratory while developing the first nuclear weapons.

Transcript: calteches.library.caltech.edu/34/3/FeynmanLosAlamos.htm Also included full text into Surely You're Joking, Mr. Feynman.

This section is about companies that design semiconductors.

For companies that manufature semiconductors, see also: company with a semiconductor fabrication plant.

Poor countries don't have a lot of money.

Therefore, you have to pick a few key the next big thing deep tech bets, and invest on those enough.

These have to be few, because your country is poor, and so you can't invest on everything.

Therefore, the bets have to be well selected, because it is useless to make several insufficient investments: you have to pick a few ones, and put enough time and money into each one of them for them to stand any chance. These bets should be made and reevaluated on 5/10 year horizons.

The key things that you have to select are:

And then you only tax those companies heavily when the start to bring in real money. These are startups remember! You only need 5 unicorns a year to call it a success. And countries should not be greedy and invest through equity, but rather recoup their investment through taxation alone.

Ciro's second removed uncle, who was a physicist at the University of Campinas, one of the best universities in the country, told him an anecdote. He had moved from fusion energy research to solar cell research. At some point, there was a research lab that needed 10 million to buy a machinery critical for their experiment. They asked and asked, and finally the government gave them only 2 million. So in the end they spent those 2 million in random ways, but of course did not achieve their research goal and no money came out of it.

He also explained how as a result of the insufficient investments, he felt clearly that some of the semiconductor production facilities related to solar power he saw simply were not able to control the production process adequately to produce consistent silicon. As a result, everything failed sooner or later as people found more and more bugs that they did not have the time to solve.

Another key investment is enticing back experienced exchange-students who have learnt new techniques to be heads of laboratory/founders to back in your country.

A fantastic initiative from Brazil for example is BRASA, which aims to put together Brazilian exchange students to make a difference back in Brazil.

Do not try to forbid external companies from selling in your country. Instead, fund your own companies to be able to fight the external market off. And if they can't, let them die and pick a different bet. Video "How Taiwan Created TSMC by Asianometry (2020)" has a good mention. Protectionism is something that Brazil notably tried to do, and look at what it led, not a single international success.