Category Archives: Physics

Q: What is dark energy?

Physicist: The universe is expanding and the rate of that expansion is accelerating.  If the universe were full of only matter (both regular and dark) and energy, then we’d expect that the expansion would be slowing.  Dark energy is the … Continue reading

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

Q: What are “actual pictures” of atoms actually pictures of?

Physicist: Actual pictures of atoms aren’t actually pictures at all. There are a few good rules of thumb in physics.  Among the best is: light acts like you’d expect on scales well above its wavelength and acts weird on scales … Continue reading

Posted in -- By the Physicist, Physics, Quantum Theory | 7 Comments

Q: If you were shrunk to microscopic size would you be able to see normally? Would you be able to see microscopic things?

The original question was: In the ‘60s sci-fi classic “Fantastic Voyage,” the crew of a submarine crew are shrunk to microscopic size and injected into the body of an injured scientist.  I realize that this film is rather sloppy from … Continue reading

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

Gravity Waves!

Physicist: A few days ago we managed to detect gravity waves for the first time.  Gravity waves were predicted a century ago by Einstein as a consequence of his general theory of relativity.  This success isn’t too surprising from a … Continue reading

Posted in -- By the Physicist, Experiments, Physics | 10 Comments

Q: Is it possible to parachute to Earth from orbit?

Physicist: Yes and no, but mostly no. It’s certainly possible to parachute safely to Earth from the top (or nearly the top) of the atmosphere, but this question isn’t about parachuting from space it’s about parachuting from orbit.  An orbit … Continue reading

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

Q: Why can’t we see the lunar landers from the Apollo missions with the Hubble (or any other) telescope?

Physicist: About why you’d expect: they’re just too damn small and too damn far away.  Nothing fancy.  That’s not to say that we can never get images, just that you need to be a lot closer.  The lunar landers are … Continue reading

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