Introduction
Physics is the most fundamental and encompassing natural science, interacting with and mutually stimulating nearly every discipline. It provides methods, tools, and theoretical language for chemistry, biology, astronomy, geology, and even psychology.
Important Clarification: Mathematics is not a natural science (its validity does not depend on experimental verification), but this doesn't mean it's "not good" — just as love is not a science, yet it is important and beautiful.
⚗️Chemistry
Highly integrated with physicsThe laws of inorganic chemistry (Mendeleev's periodic table, etc.) are in principle explained by quantum mechanics; therefore theoretical chemistry is essentially physics.
Statistical Mechanics = Physical Foundation of Thermodynamics
When countless molecules collide and transition randomly, it's impossible to track each one. Statistical mechanics provides the framework for dealing with heat and irreversibility.
- Physical chemistry: studies reaction rates, mechanisms, and transition states
- Quantum chemistry: uses quantum laws to describe bonding, energy levels, and spectra
- Organic chemistry: large molecules related to life, more complex but governed by the same physical laws
🧬Biology
Physics at the molecular levelNerve signals are propagation of electrical and membrane potential; terminals release acetylcholine to trigger muscle contraction, but how muscle fibers convert chemical energy to mechanical work remains partially unknown.
Metabolic Networks and Enzymes
The Krebs cycle is catalyzed by numerous enzymes. Enzymes are not consumed in reactions; they "lower the activation energy" by creating "valley shortcuts," enabling reactions to proceed under mild conditions.
Isotope tracing (e.g., C-14, C-13) and other physical techniques have enabled the decoding of complex metabolic pathways.
Proteins are chains of 20 types of amino acids; disulfide bonds, bulky side chains, and proline "bends" collectively determine their 3D structure and function.
DNA Double Helix and Genetic Instructions
DNA consists of double-stranded complementary base pairs (A-T, C-G). During replication, strands separate and each serves as a template for new strands; short RNA fragments carry the code to ribosomes to guide protein synthesis. The "codon → amino acid" translation rules are a core topic of molecular biology.
✨Astronomy
Closely connected to physicsThrough spectroscopic analysis, we discovered that stars are composed of the same atoms found on Earth (helium was first discovered on the Sun). Statistical mechanics and atomic physics allow us to calculate the matter distribution and radiation properties inside stars.
Stellar Energy and the Origin of Elements
Stars "burn" hydrogen into helium through nuclear fusion and progressively synthesize heavier elements in their internal "furnaces"; isotope abundances provide evidence of the "cosmic forge."
🌋Earth Sciences
Several key problems unsolvedThe instruments come from physics, but turbulence and convection make weather, volcanic, and orogenic processes difficult to model precisely; the physical properties of Earth's core under high pressure and mantle flow still require experimental and theoretical breakthroughs.
🧠Psychology and Neuroscience
Memory mechanism still unknownPsychoanalysis lacks reproducible experimental evidence. Sensation and neurophysiology can be physicalized, but how memory is encoded in neural networks remains an unsolved mystery.
Analogies with computing machines help understand the overall structure, but we are still far from explaining human behavior; simply understanding "how a dog works" would already be a major achievement.
Historical Questions and a Century-Old Problem
For physics to serve other sciences, it needs physically describable information (atomic composition, structural information, etc.). Other sciences often raise "how did things become as they are" historical questions (biological evolution, star formation, Earth's origin, etc.).
The Unsolved Central Problem: Turbulence
From high-speed water flow in pipes to stellar convection, mantle movement, and weather systems, turbulence from first principles remains unsolved; slow flow (laminar) is solvable, but real "wet water" is still difficult.
The Universe in a Glass of Wine
"The whole universe is in a glass of wine." From evaporation and reflection, to molecules and isotopes, to the distillation of rocks and the furnaces of stars, physics weaves the separated disciplines back into a whole.
"Knowing a little does not diminish the mystery — the truth is often far more wonderful than anything we can imagine."