June 03, 2007

The Discoveries: Summary

Done at last!

Here's a list of the Discoveries posts, with blurbs:

The Quantum, Max Planck, 1900.
Explained black-body spectra by introducing the idea that physical quantities can be discontinuous, an idea that many other discoveries build upon. An understanding of black-body spectra can help you understand the cosmic microwave background, too.

Hormones, William Bayliss and Ernest Starling, 1902.
Discovered the first chemical messenger in living tissues. The beginnings of biochemistry.

The Particle Nature of Light, Albert Einstein, 1905.
Max Planck's quantum taken to the next step: light behaves as though it is composed of particles. Einstein effectively discovered the photon here.

Special Relativity, Albert Einstein, 1905. Unified the electric and magnetic forces, and redefined space and time. There's a good reason why "Einstein" is in the dictionary as a synonym for "genius". Special Relativity led to General Relativity, which explained gravity and predicted things like gravitational lensing. (I screwed up my original description of one of his thought experiments. Corrected now.)

The Nucleus of the Atom, Ernest Rutherford, 1911.
Bombarded atoms with radiation, and discovered evidence of internal structure. This eventually led to a much more useful understanding of the chemical properties of atoms, and opened the new field of nuclear physics.

Sidebar: The Properties of Atoms.
The chain of logic by which the masses and volumes of the various elements were originally worked out.

The Size of the Cosmos, Henrietta Leavitt, 1912.
Discovered Cepheid variable stars, the first reliable way to measure distances beyond 500 light-years. Led to the discovery of galaxies, the expansion of the universe, and much more.

X-ray Crystallography, Max von Laue, 1912.
The single most useful observational technique discovered during the 20th century. X-ray crystallography is the way we figure out the three-dimensional structure of mollecules.

The Quantum Atom, Niels Bohr, 1913.
Combined Planck and Rutherford's work to explain many of the properties of Hydrogen. This is where quantum physics began to take off. (I really dislike my summary of this discovery. If you don't understand it, you can blame it on me not understanding it.)

Neurotransmitters, Otto Loewi, 1921.
Discovered that nerve cells, previously thought to transmit signals enirely through electricity, use chemical messengers to communicate with each other. The electric signals only travel along single nerve cells. Opened the way to the study of mind-altering chemicals.

The Uncertainty Principle, Werner Heisenberg, 1927.
Examined the way measurements can perturb a system, preventing you from knowing everything about it at once. Destroyed the ideal of absolute precision and cemented the place of probability in modern physics.

The Chemical Bond, Linus Pauling, 1928.
Extended the quantum model of the atom to the point where it could explain and predict chemical bonds, and thus the structure of simple molecules. Predicting the structure of large molecules is still beyond our computational power, but the theoretical basis is there.

The Expansion of the Universe, Edwin Hubble, 1929.
Using Cepheid variables, discovered galaxies, and the fact that they're all moving away from us as though the universe itself is expanding. (I skimped on this one. It's mostly an examination of the scientists who made these discoveries. Conclusion: there are no stereotypical scientists. The great ones are usually just the students of previous great ones. Maybe I'll revise this into a sidebar and write more about the expansion of the universe, which is pretty amazing.)

Antibiotics, Alexander Fleming, 1929. Serendipity strikes: the accidental discovery of fungi that produce anti-bacterial chemicals. Led to the search for more, and eventually to drug companies designing their own. Oh, yeah, and to the near eradication of bacterial diseases.

The Krebs Cycle, Hans Krebs, 1937.
Mapped the core energy producing metabolic pathway, present in every aerobic organism. Oxygen and food is combined to produce carbon dioxide, water, and ATP, the molecule that powers everything in a cell. A key step in understanding the big networks of chemical reactions that keep us alive.

Nuclear Fission, Lise Meitner and Otto Hahn, 1939.
Discovered that with a little nudge, big atoms will fall apart. Led to nuclear power and nuclear bombs.

The Movability of Genes, Barbara McClintock, 1948.
Really, the discovery all kinds of complexities in genetics. Genes that switch other genes on and off, DNA that gets moved from one part of the chromosome to another, genes that affect mutation rate, structural changes of chromosomes, and much more.

The Structure of DNA, James Watson, Francis Crick, and Rosalind Franklin, 1953.
X-ray crystallography and cardboard models used to figure out the three-dimensional structure of the molecule that carries genetic information. The most important bit is the way the structure of DNA automatically leads to replication.

The Structure of Proteins, Max Perutz, 1960.
Showed how to understand the function of proteins (in this case Haemoglobin), the molecules that do practically everything in a cell. Opened the way to a detailed understanding of the way cells work.

The Cosmic Microwave Background, Arno Penzias and Robert Wilson, 1965.
Discovered the light leftover from a time when the universe was dense enough for all matter to take the form of plasma. Strong evidence that the universe has been expanding for quite some time now.

A Unified Theory of Forces, Steven Weinberg, 1967.
Found a way to describe electricity, magnetism, and the weak interaction as a single, unified system. Elegant.

Quarks, Jerome Friedman, Henry Kendall, and Richard Taylor, 1969.
Bombarded protons with radiation, and discoved evidence of internal structure. This time we're certain we've found the indivisible particles, right?

Genetic Engineering, Paul Berg, 1972.
Hijacked various enzymes to hijack a virus to insert arbitrary DNA into a cell's genome. Allows us to do things that were once impossible.

And that's it, for now. Credit must go to Alan Lightman for collecting these papers, researching them, and putting them all together for us in his book, which inspired me to spend so much time writing about them myself.

Hope you learned as much as I did!


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