So, I wondered what do I think? What are the ten most remarkable scientific ideas?
I have used the following rough criteria. The idea
- is far from obvious
- is often not thought about because we have become so used to it that we take it for granted
- may evoke not just an intellectual response but also a somewhat emotional one of wonder and awe
- is profound but can be simply stated
- is a specific law, principle, or property, rather than a general scientific idea such as that laws can be encoded mathematically, experiments must be repeated, the same laws apply everywhere in the universe.
1. The universe had a beginning.
2. Time has a direction.
3. The fundamental constants of nature are fine-tuned for life.
4. All elementary particles are identical.
5. Energy is quantised.
6. Particles are fields and fields are particles.
7. All of life has a common molecular template (DNA and proteins).
8. Everything is made from atoms. The periodic table of chemistry.
9. Evolution: many small genetic variations can produce biological diversity.
10. Emergence and reductionism. Complexity can emerge from simplicity.
Here are some runners up. Some are more specific versions of those above.
A. The genetic code. DNA prescribes protein synthesis.
B. Genetic information is encoded in DNA.
C. Water is a unique liquid with remarkable properties with important implications for biomolecular function.
D. Diffraction of waves [x-rays, electrons, neutrons] can be used to determine the atomic structure of materials.
E. The geometry of molecules and chemical reactivity is determined by quantum mechanics [and can be described by potential energy surfaces].
F. The second law of thermodynamics: entropy is a state function. Free energy determines stability of open systems.
G. Symmetry constrains physical laws; spontaneously broken symmetry leads to different physical interactions and states of matter.
H. Macroscopic properties are determined by microscopic properties.
I. Protein folding. Amino acid sequence uniquely determines protein structure which determines function.
I am missing anything about earth science due to my ignorance.
Presumably, others have compiled such lists and taught courses based on them. Please let me know. One example is a course by Robert Hazen and James Trefil. Each chapter is centred around a great idea.
What do you think?
How would you change the above lists?
I would come up with the following top few:
ReplyDelete0. There is no centre in the universe and physical laws are the same everywhere;
1. Space-time is relative and can be curved;
2. Velocity and position can not be simultaneously measured with absolute certainty, even in principle;
3. Vacuum is not empty;
4. Universe is expanding;
I am not quite sure about point 3 for the following reasons:
ReplyDelete1) Firstly, fine-tuning of the fundamental constants is only one of three explanations for the constancy and fineness of the fundamental constants; the other two being the multiverse, and Wheeler's it-from-bit. (The multiverse is not testable but so aren't many aspects of quantum mechanics.)
2) Moreover, although recent experiments suggests temporal constancy of the fundamental constants, I am not sure if this is resolved. For example, as you suggest in point 9, without evolution as an explanation for speciation almost everything about life would seem fine-tuned. It is not clear to me that the universe did not evolve from similar simple rules; this is somewhat along the lines of the it-from-bit theory, where --- because information is assumed to be an innate property of the universe --- we shouldn't be surprised if information content keeps increasing (If so, why is information an innate property? That might still be counted as remarkable, of course.)
3) Finally it seems to me that a case for fine-tuning is almost always made in absolute terms; it could be that the constants (some of them at least) are tuned only relative to each other, which then indeed does not require fine-tuning. For example Weinberg makes the point about one of the resonance energy-levels of carbon-12 that are required for its abundant production, one of the oft-cited arguments for fine-tuning: he says that if measured with respect to carbon's ground state, then it is indeed a 1% fine-tuning; but if measured, as he argues should be, with respect to beryllium's energy levels (for fusion with helium), the tuning is only within 20%, which is not very fine.
About point 2, given our current theories, I agree. It seems to me that time entering our major theories like quantum mechanics or general relativity not in quite the same way as space, is a sign of this (unless string theory suggests an emergent time from AdS/CFT correspondence?). As a non-expert, I am already a bit wary about stretching these points!
And on a general note, I think most remarkable facts are only so because of the order in which we discover the laws: I believe Witten says somewhere* that he can conceive of an alternate planet where string theory is formulated before quantum mechanics, and even before classical mechanics.
*Sorry to name-drop without the reference!
1. The speed of light is a constant in all inertial frames
ReplyDelete2. All fundamental particles come in only two known types - bosons and fermions
Your number 4 has my strong support.
ReplyDeleteAlso, the universe obeys universal laws that can be described using simple mathematics.