Learning Physics
This is the fourth post in the series on things to learn, see the intro or posts on math and programming skills. This post will discuss the physical sciences.
Should Studying Science be Mandatory?
Most people won't become scientists so they can learn science to satisfy their curiosity about how the world works and came to be, even if it’s not practical. Beyond the most basic concepts, the physical sciences should be an optional part of the K-12 curriculum. Students who are interested in science can be encouraged to pursue it further since they will appreciate it more and a fraction of them will later use it in their careers. Other students won’t find it as interesting and are unlikely to become scientists themselves, but they can always catch up later if they change their minds.
What role do schools have?
Once a student commits to learning a topic in high school or college, they can join a class as a way to 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 and incentive system to help people can learn. Outside of school, when you’re just learning on your own, it’s harder to "force" yourself to get through difficult topics that you’re interested in. On the other hand, you can also completely skip topics you’re not interested in. Schools should provide more flexible courses so students can still commit to a certain curriculum, but one that they can customize.
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 so you can adjust your curriculum accordingly.
Question: Can you learn physics without advanced math?
Answer: 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, 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 that seem worth learning more about, with some miscellaneous comments and questions.
Mechanics - Force & Motion & Inertia
Understanding the basic concepts intuitively
Example - Newton’s third law (action and reaction) can be more easily understood if you imagine every surface is covered in springs.
The basic formulas and their calculus
Example question: Intuitively, why is Kinetic Energy proportional to v² when momentum is proportional to v (velocity)?
Answer: Lets' say you want to stop a frictionless moving car by attaching a friction block to it, which will drag on the ground with a constant force. A car going 2x as fast will take 2x as much time to stop (since it has 2x the momentum). However it will take 4x as much distance to stop the car (since the car was going faster initially). All that distance involved the same rate of friction heat creation, so the car going 2x as fast must have 4x the Kinetic Energy. 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 example shows that some math is needed to understand even basic physics. (This example is also related to 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? (See also Feynman on the conservation of energy.)
Gravity
How Newton discovered the law of gravity from a better understanding of motion.
(I.e. how Newton built on Galileo to create Newton's laws of motion, then connected them with Kepler's laws of planets and then connected that with the moon's motion and discovered 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.
When reading Einstein's writings, it’s interesting 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. The first law is about the "absolute" store of energy, which never changes. But energy can only be used when it flows from "high" to "low" states, and over time energy differences even out so entropy always increases. The book also 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 theories of thermodynamics developed from the technological development of steam engines (compare this also with how computers developed)
Practical applications in everyday life
Why opening a fridge won't cool the room
comparing the efficiency of an electric and gas stove, or an electric and gas car
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?
Consider reading parts of Scott Aaranson's Quantum computing since Democritus (or the lecture notes)
Interpretations of quantum indeterminacy
See lecture notes
Bohemian mechanics (pilot wave theory)
See also articles in Stanford Encyclopedia of Philosophy
Other topics in the physical sciences
Astronomy & astrophysics - How the universe developed
Astronomical spectroscopy - interesting unification of laws on earth and in the stars
The formation of all elements (Big Bang nucleosynthesis and 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 the 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?
The properties of more complex molecules; eventually this overlaps with biochemistry
Earth science
Development of earth - how did Earth initially form and develop? How did life eventually affect the atmosphere?
Earth's magnetism - how it’s generated by internal motion, how it changes over time, how it interacts with solar radiation
Weather - what causes the weather, the basics of warm and cold fronts, simple weather predictions, advanced weather predictions, the butterfly effect
Global warming - measuring it, predicting it, estimating its impact, counter-measures