Yearly Archives: 2011

Q: What causes buoyancy?

The original question was: I know that the buoyant force on an object equals the weight of the liquid that it displaces.  However, I have some questions as to what it means to ‘displace’ a liquid,  for example, does an … Continue reading

Posted in -- By the Physicist, Physics | 3 Comments

My bad: If atoms are mostly made up of empty space, why do things feel solid?

Physicist: Thanks to a comment in the original post, I did a little research and found that I was wrong, wrong, holy crap wrong.  Here’s some of that comment: “The source of the ultimate “excluded volume” forces is entirely quantum … Continue reading

Posted in -- By the Physicist, Mistake, Quantum Theory | 30 Comments

Q: How many mathematicians/physicists does it take to screw in a light bulb?

Mathematician: Theorem (Bulb Screwing) It only takes one mathematician to screw in a light bulb. Proof: Let the “bulb screwing number” of a profession , be the minimum number of people of profession that must be assembled to screw in … Continue reading

Posted in -- By the Mathematician, -- By the Physicist, Brain Teaser, Philosophical | 23 Comments

Q: Why is it that (if you exclude 2 & 3) the difference between the squares of any two prime numbers is divisible by 12?

Physicist:  That’s a really cool property! Every prime number (other than 2 and 3) can be written in the form 6j+1 or 6j+5.  For example, 17 = 6(2)+5 and 31 = 6(5)+1. This is because numbers of the form 6j, … Continue reading

Posted in -- By the Physicist, Brain Teaser, Math, Number Theory | 8 Comments

Q: Why does relativistic length contraction (Lorentz contraction) happen?

Physicist: This probably should have come before the last post. Length contraction is a symptom of “tilted now planes”.  For someone moving past you events physically in front of them happen earlier than they should (according to you), and events … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 24 Comments

Q: Why does Lorentz contraction only act in the direction of motion?

Physicist: A lot of things get messed up by relativity, like when and where stuff happens, how massive things are, or how time passes.  Length contraction is an effect that literally makes things shorter in the direction of motion.  So … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 22 Comments