Category Archives: Physics

Q: What would Earth be like to us if it were a cube instead of spherical? Is this even possible?

Physicist: The Earth is really round.  It’s not the roundest damn thing ever, but it’s up there.  If the Earth were the size of a basketball our mountains and valleys would be substantially smaller than the bumps on the surface … Continue reading

Posted in -- By the Physicist, Astronomy, Physics | 85 Comments

Q: How do velocities add? If I’m riding a beam of light and I throw a ball, why doesn’t the ball go faster than light?

Physicist: Everything in special relativity, no matter how weird, eventually boils down to the speed of light being the same to everyone.  It’s just not immediately obvious how.  The very short answer is: if v and w are pointing in … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 23 Comments

Q: What is the universe expanding into? What’s outside the universe?

Physicist: Probably nothing.  We do know that the universe doesn’t need anything to expand into, and we haven’t seen any evidence that there is anything outside of the universe.  But there has still been some speculation. In the last hundred … Continue reading

Posted in -- By the Physicist, Astronomy, Philosophical, Physics | 63 Comments

Cheap experiments and demonstrations for kids.

The original question was: I recently had to cover teaching children (Age 10 – 14) physics for an hour and I was wondering if you could think of any physics experiments that require few or cheap materials with interesting results … Continue reading

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

Q: Is there a single equation that proves black holes are real?

Physicist: Nope! Using general relativity (which has plenty of equations), and a little borrowed knowledge from other fields (to describe star collapse), you can show that black holes should exist.  But unfortunately there are no proofs in physics, just experimental … Continue reading

Posted in -- By the Physicist, Astronomy, Philosophical, Physics | 11 Comments

Q: As a consequence of relativity, objects becomes more massive when they’re moving fast. What is it about matter that causes that to happen?

Physicist: The laws of the universe are relativistic.  That is, Einstein was right and Newton, although accurately and intuitively describing the world around us, was wrong.  When you try to translate the cleaner Einstein laws into a Newtonian form you … Continue reading

Posted in -- By the Physicist, Physics, Relativity | 12 Comments