Category Archives: — By the Physicist

Q: Why are orbits elliptical? Why is the Sun in one focus, and what’s in the other?

Physicist: This question always bothered me too.  The short answer is: it falls out of the math.  Specifically, the math of first year physics and second year calculus.  The fact that the Sun is in one focus is just one … Continue reading

Posted in -- By the Physicist, Astronomy, Physics | 55 Comments

Q: What would happen if everyone in the world jumped at the same time?

Physicist: Sounds like a party! It would create a spherical wave that would descend through the Earth, focus at the core, and then expand again hitting the entire surface again, at more or less the same time, a little under … Continue reading

Posted in -- By the Physicist, Physics | 8 Comments

Q: How can electrons “jump” between places without covering the intervening distance?

Physicist: Frequently in quantum mechanics you’ll find that particles are restricted to only a certain set of states or locations, and yet somehow they can move from one to the next. It’s like moving between islands without crossing any water. … Continue reading

Posted in -- By the Physicist, Physics, Quantum Theory | 20 Comments

Q: Why do we only see one rainbow at a time?

Physicist: A rainbow is an angle-dependent illusion.  They don’t actually exist anywhere, they just appear to.  Since they can only exist at a particular angle (with respect to you and the Sun), you can never see them anywhere else in … Continue reading

Posted in -- By the Physicist, Physics | 27 Comments

Q: Why does putting spin on a ball change how it moves through the air?

Physicist: This question is especially perplexing after a first year physics course, where every question starts with “ignoring air resistance…”. There are a couple of different way to approach the answer, but I like this one best. Way back in … Continue reading

Posted in -- By the Physicist, Physics | 19 Comments

Quantum mech, choices, and time travel too!

Physicist: Recently I sent a series of emails back and forth with a reader that seem interesting enough to post. Conversations (near a chalkboard especially) are the best way to learn just about anything.   Q: I wake up at … Continue reading

Posted in -- By the Physicist, Philosophical, Physics, Quantum Theory | 6 Comments