Category Archives: Physics

Q: How can I set up a random gift exchange that’s different from year to year?

The original question was: I’ve got a large family and we do a yearly gift exchange one person to one person. And I’d like to make a algorithm or something to do random selection without repeating for some time. And … Continue reading

Posted in -- By the Physicist, Combinatorics, Experiments, Math | 2 Comments

There’s something new under the Sun!

Physicist: Good news! On October 19th, for the first time in history, we detected an object inside of our solar system that originated somewhere else.  It’s a rock the size of a stadium that passed inside of Mercury’s orbit and … Continue reading

Posted in -- By the Physicist, Astronomy | 9 Comments

Q: Is it more efficient to keep keep a swimming pool warm or let it get cold and heat it up again?

The original question: I’m having a debate with my wife that I think you can help us resolve.  We have a swimming pool in our back yard.  It has an electric heater, which we set to keep the pool water … Continue reading

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

Q: What determines the size of the bright spot when you focus sunlight with a lens?

Physicist: This question really appeals to my ten-year-old self.  If you’ve never tried to burn something with a lens, collect three pairs of sunglasses, a magnifying lens, and something you dislike.  On a bright day, put on all three pairs … Continue reading

Posted in -- By the Physicist, Equations, Geometry, Math, Physics | 1 Comment

Q: If time is relative, then how can we talk about how old the universe is?

Physicist: One of the most profound insights ever made by peoplekind is that time is relative.  This isn’t some abstract idea, mistake, or mathematical artifact.  If you have two identically functioning clocks, you can start them together, move them to … Continue reading

Posted in -- By the Physicist, Astronomy, Physics, Relativity | 61 Comments

Q: How can carbon dating work on things that were never alive?

Physicist: It doesn’t. Carbon dating is the most famous form of “radiometric dating”.  By measuring the trace amounts of radioactive carbon-14 (so named because it has 6 protons and 8 neutrons) in a dead something and comparing it to the … Continue reading

Posted in -- By the Physicist, Particle Physics, Physics | 6 Comments