Sunday, June 28, 2020

Biology vs. Physics

This is the fifth post in the series on things to learn. See the intro or the last post on learning physics.

The natural sciences are divided into two branches: the physical sciences (primarily physics and its derivatives) and the life sciences (a.k.a biology). Biology is different than physics in many ways, which affect how one learns it:
  • Less Math - Math is fundamental to all of physics but it's more incidental in biology. This can make biology easier to learn for many people.
  • More complexity - As challenging as physics is, it's ultimately about simple concepts. But biology is about life, which is complicated.
    • Textbooks filled with terminology and small details can make learning biology more tedious. However I think there may be a way to focus more on the overall concepts involved than on the exact terminology and details. When learning for general curiosity, you don't need to know every exact term, you can just learn the terms that will be repeated enough to be worth learning. (See XKCD's thing explainer for an exaggerated example of explaining concepts with less terminology.)
  • Unknown frontier - Physics has already solved most areas that a layman would be interested in. The current frontier of physics deals with problems that would be hard a non-physicist to relate to, and it would take years of learning to understand them. Meanwhile biology is filled with unsolved questions in every area from neuroscience to nutrition to genetics to diseases, and one encounters these issues right away. 
    • Update: this point is debatable since there are unsolved questions in physics that a layman would be interested in.
  • Practical - If you're not an engineer you're unlikely to use knowledge of physics for anything practical. But biology topics like nutrition and disease are relevant to living longer and healthier lives.
There are other ways that physics and biology differ:

Inherent or accidental?
It seems that many parts of physics could be intuited based on other principles and couldn't be any other way:
  • Falling objects - Galileo argued against the Aristotelian idea of motion (that heavier objects fall faster) not only with experiments but by pointing out the logical paradoxes that would result.
  • Inverse-square law - While one could imagine forces decreasing in other ratios, decreasing in proportion to r2 seems the most logical since a force radiating out from a point will spread out according to the formula for a sphere's surface (4πr2).
  • Relativity - While most people wouldn't intuitively think of Special Relativity, it seems Einstein was able to recognize that it was the "only way" possible. He was able to derive this based on a deep understanding of the implication's of Maxwell's equations, and he may not even have been aware of the Michelson-Morley experiments.
Questions in physics are still resolved through experiments, but maybe this is to demonstrate the truth to those who don't have the right intuitions of the way nature "needs" to be. When Einstein was asked what if the experiments had disproven his theory of General Relativity, he said "then I would have felt sorry for the dear Lord. The theory is correct." While physics cannot just be pure deduction like mathematics, it's the closest one can get. The eventual goal of physics is to find the theory of everything from which everything else is derived.

Biology however deals with the complex messiness of life, and there's many ways to be a living thing. Scientists can may make predictions based on the data they have, but they can't derive how systems "must" be. Living things are "accidental" in the Aristotelean sense of having traits that they happen to have but could lack.

Ancient and medieval physics used teleological explanations as Aristotle emphasized the "final cause" (or purpose) as one of the "four causes" to explain the way things are, and argued against Democritus who rejected it. Modern physics, starting with Francis Bacon, returned to the physics of Democritus and dropped "purpose" from consideration. Since Isaac Newton, the motion of heavenly and earthly bodies is explained with simple physical laws, without reference to any goal or "natural place" of matter. 

Unlike rocks or stars, living things act with purpose. Even a simple bacterium seeks food, evades predators and maintains its internal state. While scientists no longer use theological explanations to explain why organs and organelles have certain functions and designs, these elements still exist and are worthy of explanation. Some use the term teleonomy to distinguish modern explanations of biological purpose from earlier ones.

In short physics is about mathematical explanations for "simple" things from atoms to galaxies, while biology is about the complexity of life, with all its purpose. 

Tuesday, June 16, 2020

Learning the Physical Sciences

This is the fourth post in the series on things to learn. See the intro or the posts on math and software development.

Should Studying Science be Mandated?
Most people won't become scientists so learning science is about satisfying curiosity about how the world works and came to be, not about learning a practical or career-oriented topic. Beyond the most essential understanding of how the word works, the physical sciences should be an optional part of the K-12 curriculum. Students who are interested in science can be encouraged to learn it since some of them may appreciate the opportunity and a fraction of them will later use it in their careers. Those who are uninterested are unlikely to become scientists themselves, but they can always catch up later if they desire to.

Once a student commits to learning a topic in high school or college, they can force themselves to continue learning it even when it's difficult, since they want to do well in the course. This is the one benefit of schools - they provide a structure or incentive system where people can learn. Once someone leaves school and is just learning on the side for enlightenment, they're less likely to "force" themselves through difficult topics. However, when you're learning on your own, you can choose to learn the most interesting topics.

Learning the Concepts in Science
If you're learning science just to satisfy curiosity, you don't need to learn every technical detail covered in textbooks.

Q: Can you learn physics without advanced math?
A: I think so:
  • Many areas of physics (such as mechanics) can be understood with basic algebra and maybe a sprinkle of simple calculus.
  • Even in other areas, it seems one can get at at least a partial conceptual understanding without covering all the mathematical details.
While a researcher or engineer may need to know all the mathematical nitty gritty, someone learning physics for knowledge can likely skip over some of these details. In the past it was even possible to make significant discoveries in physics with limited knowledge of math. For example Michael Faraday was "one one of the most influential scientists in history" despite the fact that "his mathematical abilities... did not extend as far as trigonometry and were limited to the simplest algebra". (Though even there, James Maxwell's equations were needed to fully understand the implications of Faraday's discoveries.) Physics became more complex over time, so later developments in physics require more math to truly understand them, but one can still learn a simpler version of any topic.

Books that cover concepts in Physics
These are books that give an overview of physics and its development:
  • Seven Ideas That Shook the Universe - different paradigms in physics: Copernican astronomy, Newtonian mechanics, energy and entropy, relativity, quantum theory and conservation principles & symmetries.
  • The Evolution of Physics (By Albert Einstein and Leopold Infeld) - As summarized by the table of contents, it covers The Rise of The Mechanical View; The Decline of the Mechanical View; Field, Relativity; and Quanta. Slightly similar to the above book, though from Einstein's perspective.
  • The Character of Physical Law (by Richard Feynman) - Instead of covering all of physics, it goes through certain ideas as examples of physics. This is the written version of a series of lectures by Feynman so it isn't as edited as the above books, but it contains Feynman's unique style.

Specific Topics in Physics
Here are some interesting topics in physics they seem worth learning more about.
  • Mechanics - Force & Motion & Inertia
    • The basic formulas and their calculus.
      • Example question: Intuitively, why is Kinetic Energy (KE) proportional to v2when momentum is proportional to v (velocity)?
        Answer: Lets' say you want to stop a frictionless moving car by putting a friction block on which drags on the ground with a constant force. A car going 2x as fast will take 2x as much time to stop since, as expected since it has 2x the momentum. However it will take 4x as much distance to stop the car. All that distance involved the same rate of friction heat creation, so the car going 2x as fast must have 4x the KE. Similarly if you want to drop a block and have it go 2x as fast as another block, you'll need to raise it to 4x the height. This was also a controversy between followers of Newton and Leibniz, see Vis Viva.
    • How/why is inertia and conservation of momentum so fundamental in all of physics?
  • Gravity (Newtonian)
    • How Newton discovered the law of gravity from a better understanding of motion.
      (I.e. how Newton built on Galileo to create his Newton's laws of motion, then connected them with Kepler's laws of planets and then connected that with the moon's motion and universal gravitation.)
    • Basic math of satellites and planets in orbit
    • Key concepts in general relativity
  • Electromagnetism
    • Understanding what electric and magnetic fields are are and how they interact with charged particles.
    • How special relativity resolved issues raised by Maxwell's equations. 
      • Interesting when reading Einstein's writings, how strong his intuition was to avoid any special frames of reference and how this took priority over other intuitive ideas such as about absolute time...
  • Thermodynamics
    • What is entropy? Besides the fundamental meaning for particles, how does it affect non-thermodynamic order? Whats was the entropy of the universe initially? How does gravity affect entropy? (See also heat death paradox, as well as this question.)
      Understanding Physics (by Isaac Asimov) gives basic explanation the laws of thermodynamics. First law is about the "absolute" store of energy. But energy can only be used when it flows from "high" to "low". And over time differences even out so entropy increases. Book has this more philosophical observation:
      We thus find there is an odd and rather paradoxical symmetry to this book. We began with the Greek philosophers making the first systematic’ attempt to establish the generalizations underlying the order of the universe. They were sure that such an order, basically simple and comprehensible, existed. As a result of the continuing line of thought to which they gave rise, such generalizations were indeed discovered. And of these, the most powerful of all the generalizations yet discovered — the first two laws of thermodynamics — succeed in demonstrating that the order of the universe is, first and foremost, a perpetually increasing disorder.
  • How does "information" as a physical concept connect to this? (see wikipedia and stanford article.)
    • Is the second law of thermodynamics more "proven" than other natural laws?
    • How the theoretical science developed from the technological development of steam engines (and compare with how computers developed) 
    • Practical applications in everyday life (e.g opening fridge won't cool room)
  • Nuclear physics
    • The nuclear bonds (and how E=MC2 not that relevant).
      Compare nuclear bonds with chemical energy.
      (Bonus: the weak force and how it relates to electromagnetic force) 
  • Quantum mechanics - to what extent can it be understood by a layman?
Other topics in the physical sciences
  • Astronomy & astrophysics - How the universe developed
    The formation of all elements (Stellar nucleosynthesis). The cycle of stars. How matter regrouped after stars exploded.. (See Wikipedia on Stellar population.)
  • Chemistry
    • how does the number of protons/electrons determine the properties of elements?
      • Much of this is more basic chemistry, as seen in repetition in the periodic table
      • Sometimes the specifics of how properties like color are determined can involve more complex areas, e.g. need relativistic quantum mechanics to explain why gold is gold-colored instead of silver. 
    • How does the structure of electrons in chemical compounds determine their properties? 
  • Earth science
    • Development of earth
    • Earth's magnetism
    • Global warming

Thursday, June 11, 2020

Skills to Learn for Software Developers and Others

The previous post discussed math topics I'm interested in learning, this will discuss programming-related skills that are important and I'd like to improve at.

While there are many technical skills important for software developers, this post will cover general (non-programming) skills, and programming skills that are useful for other careers.

General skills
These are general skills that are important in software development and in many other office jobs as well:
  • Focus - Often one encounters difficulties and it's easy to get frustrated and distracted. The test is still failing? Might as well browse emails or the web. But switching tasks breaks up the train of thought you had so you'll take even longer to solve the problem. (One second, just going to check my emails. Now where was I..? ) Often one needs relentless focus on an issue in order to make progress quickly. And not just "guess and check" thinking where you randomly try different things hoping you'll find a solution, but "binary search" thinking where you hone in on the issue until it's solved. There are times when it can be helpful to take a break and return to the problem later, but that should be done after you've given the problem solid focus and hit a wall. 
  • Typing 
    • While raw typing speed should never be a significant bottleneck when programming, any effort on typing or fixing typos can take your focus off the main issue at hand.
    • Programmers type far more chats and emails than actual code; it's best to do this as quickly as possible.
    • Besides basic typing skills, one should also be comfortable with the relevant keyboard shortcuts for their OS, terminal and IDE. Moving to the mouse is another micro distraction that is best avoided. 
  • Memory / note system - When learning programming one struggles with remembering all sorts of details about language and syntax, but eventually you get the overall hang of how things work, and can easily look up syntax as needed. But there will still be many issues that you solve (or get help with) where you'll want to remember the solution for the future, and your memory isn't always enough. It's useful to have a note or bookmark system to quickly lookup how to do things.
General programming skills 
These are programming skills that are useful for many jobs, not just for professional software developers: 
  • SQL - The world is built on SQL, often with a few other layers stacked on top of it. Besides writing SQL when developing an actual application, it's essential in many other cases such as:
    • analyzing experiments or general usage of a product
    • finding sample data to test something out
    • querying logs to debug an issue in production
Many alternatives to SQL have been developed, but there's often no avoiding SQL itself. It helps to become proficient with it so one can quickly find the data they need and avoid common bugs such as accidentally duplicating rows. Many other professions, such as analysts or product managers, will also find it useful.
  • Regex - Programming is often about finding the right example to base your code on, or about quickly finding and replacing text. Regex makes this faster. Anyone who deals with large data or texts will find it helpful as well. 
  • Scripting - Sometimes it's useful to write a quick script to help generate code or analyze data. Non-professional programmers may want to write a script to help with their science research or with their spreadsheets.
Worth learning
While one can learn many skills on the job, often it's helpful to take a step back and learn the subject in-depth. This way you can learn how to do something properly instead of just finding the easiest solution at the time. This would be an area where schools could help, but as expected, they don't give these subjects their proper due.

Tuesday, June 2, 2020

Maths to Learn

In the previous post I discussed the five categories of knowledge. These posts will go through different subjects that I'm interested in, starting with Mathematics.

  • Theory of computation - key ideas of computation. It's interesting how a mathematical idea about computation grew into physical computers.
    • Turing and Godel's theorems and how they relate to each other. Is there a way one can exclude the halting problem and build a machine that can determine if almost everything will halt?
    • How high level code actually executes on a machine.
  • Review of basic calculus
    • Intuitive understanding of derivatives and integrals.
    • Optimization and related-rates problems
    • Applications to physics
  • Probability & statistics - Ultimately all knowledge comes down to probabilities. Statistics are useful for interpreting studies and experiments and everything else.
    • Review fundamentals of probability
    • Bayesian probability and statistics
    • Pascal's triangle, the normal distribution, the central limit theorem
    • Applying statistics to real-world examples
    • Tools for stats (e.g Google sheets, R, Python)
    • Stats for machine learning
  • Using Mathematica for real world math problems

Besides for calculus, it's interesting how little these topics are taught in schools. Many students don't know basic topics like fractions well and schools should focus on teaching them better. Other students can learn more advanced topics but it does not need to be limited to a narrow curriculum of trigonometry and geometry and specific parts of algebra. (See also my post from 2011.)

Carthago delenda est 

Monday, June 1, 2020

The Case for The Case against Education

In The Case against Education Bryan Caplan argues that education is primarily about signaling certain traits as opposed to learning useful skills, and that much of it is a waste for society. Here are some of my thoughts on the book:

  • Agree with much of the book. It shouldn't surprise most people to hear that schools teach a lot of useless stuff.
  • Caplan focuses on the US but it would be interesting to look at other countries. For example, Caplan dismisses online education as unlikely to become accepted by employers, but Open University is a remote learning option founded in 1969 that is a respectable option in many countries.
  • Caplan's big claim is that schools mainly signal certain traits (such as intelligence and conscientiousness), and he particularly emphasizes that schools signal "conformity" and that employers care strongly about it. I think this depends a lot on industry and the culture of the companies. For example, tech companies seem less concerned about conformity, though perhaps that's why many of them don't require college degrees. Other companies may still require degrees but they may just be conformist themselves without actually requiring conformists for the job. If it became more accepted to not go to college and to hire without degrees, how many companies would still insist on it?
  • Instead of just theorizing about what employers are looking for, it would be interesting to actually check. Big companies have specific criteria they look for when hiring applicants, and they also study the traits of their successful employees. For example, see this article on Google's hiring practices.
  • Not sure if Caplan gets this critique too often but in certain cases I think he gives school too much credit. For example, he says practical majors like engineering primarily involve learning useful skills. In my experience with Computer Science, much of the major consisted of theoretical math instead of practical topics. (That's why there's a practical-focused programming course called The Missing Semester of Your CS Education).
  • Caplan says some pretty extreme things, such as saying there should be zero government funding of education, or that it would be better if education was more expensive. As if the cost of education in America isn't high enough! There are better ways to beat credential inflation than making education more expensive, and ways that would be less unfair to lower-income people. For example, one could encourage companies to do more interviewing or hiring on a college-blind basis (I think the hiring platform triplebyte tried this to some extent.)
  • This may be an issue in general with books, but I'm not sure how much I remember from the middle of the book. I think people can just read the beginning and end of the book to get the gist of it.

(Review originally posted to Reddit.)