Category Archives: Biology

Q: If the number of ancestors you have doubles with each generation going back, you quickly get to a number bigger than the population of Earth. Does that mean we’re all a little inbred?

Physicist: In a word: yes.  But it’s not a problem in large populations. The original questioner pointed out that in the age of Charlemagne (more or less when everybody’s 40-greats grandfolk were living) the world population was between 200 and … Continue reading

Posted in -- By the Physicist, Biology, Evolution, Probability | 7 Comments

Q: What is radioactivity and why is it sometimes dangerous?

Physicist: Here’s every particle you’ve ever interacted with: protons, neutrons, electrons, and photons*.  Dangerous radiation is nothing more mysterious than one of those particles moving crazy fast. The nucleus of some kinds of atoms are unstable and will, given enough … Continue reading

Posted in -- By the Physicist, Biology, Particle Physics, Physics | 1 Comment

Q: Why does carbon dating detect when things were alive? How are the atoms in living things any different from the atoms in dead things?

Physicist: As far as carbon dating is concerned, the difference between living things and dead things is that living things eat and breathe and dead things are busy with other stuff, like sitting perfectly still.  Eating and breathing is how … Continue reading

Posted in -- By the Physicist, Biology, Particle Physics, Physics | Leave a comment

Q: Why can some creatures walk on water yet I (a human) can’t?

Physicist: Surface tension. There are a lot of details and phancy physics behind surface tension, but the main idea behind surface tension comes from what separates liquids from gases.  Small things (like individual molecules) have a tendency to stick to … Continue reading

Posted in -- By the Physicist, Biology, Physics | 5 Comments

The nuptial effect

Every day, on average, 2-3 physicists get married.  On Saturday I’ll be attempting to push that average to as high as 3-4. So (for our regular readers), there’ll be a longer gap between posts than usual.  The future Mrs. Physicist … Continue reading

Posted in -- By the Physicist, Combinatorics, Evolution | 22 Comments

Q: Why doesn’t life and evolution violate the second law of thermodynamics? Don’t living things reverse entropy?

Physicist: In very short: nope. The second law of thermodynamics is sometimes (too succinctly) stated as “disorder increases over time”.  That statements seems to hold true, what with all of the mountains wearing down, machines breaking, and the inevitable, crushing … Continue reading

Posted in -- By the Physicist, Biology, Entropy/Information, Evolution | 14 Comments