Category Archives: Physics

Q: Satellites experience less time because they’re moving fast, but more time because they’re so high. Is there an orbit where the effects cancel out? Is that useful?

The original question was: I read that due to time dilation from both gravity and speed, GPS satellites need their clocks adjusted to match Earth’s time or else the whole idea would fall flat on its face. So my question … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 11 Comments

Q: What would happen if a black hole passed through our solar system?

Astronomer: Most black holes form when a star which is ten times more massive than our Sun runs out of fuel for fusion. This causes the star to collapse, explode as a supernova, and, if enough material is left over … Continue reading

Posted in -- Guest Author, Astronomy, Paranoia, Physics | 81 Comments

Q: If you are talking to a distant alien, how would you tell them which way is left and which way is right?

Physicist: Assuming this question isn’t about interstellar political leanings, the answer is: it’s tricky, but it can be done. This is worth trying out just once in your life.  Try to define left and right for someone using only physical … Continue reading

Posted in -- By the Physicist, Particle Physics, Physics | 26 Comments

Q: Would it be possible in the distant future to directly convert matter into energy?

Physicist: You hear about nuclear devices taking advantage of “E=mc2” to turn matter into energy, so nuclear power seems like it might be a good way to go.  But it so happens that everything that releases energy loses mass in … Continue reading

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

Q: What’s the difference between anti-matter and negative-matter?

Physicist: Anti-matter is exactly the same as matter, but different.  If you, and everything else on the planet, were suddenly turned into anti-matter, you’d never know the difference.  While the “anti-” of anti-matter may seem to give it an air … Continue reading

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

Q: Why does gravity make some things orbit and some things fall?

Physicist: This subtlety was one of the great insights of Newton; that the “falling apples” force and the “circling planets” force are one and the same. Whether gravity pulls an object into orbit or just “makes it fall” depends on … Continue reading

Posted in -- By the Physicist, Astronomy, Physics | 15 Comments