Category Archives: — By the Physicist

Q: Can planes (sheets) be tied in knots in higher dimensions the way lines (strings) can be tied in knots in 3 dimensions?

Physicist: Yes! Mathematicians are pretty good at talking about things in spaces with any number of dimensions.  Sometimes that math is fairly easy and even intuitive.  For example, a line has 2 sides (ends), a square has 4 sides, a … Continue reading

Posted in -- By the Physicist, Geometry, Math | 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

Q: How bad would it be if we accidentally made a black hole?

Physicist: Not too bad!  Any black hole that humanity might ever create is very unlikely to harm anyone who doesn’t try to eat it. Black holes do two things that make them (potentially) dangerous: they eat and they pop.  For … Continue reading

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

Q: What if gravity acted like magnetism?

Physicist: The problem with magnetism and the electric force is that they tend to cancel themselves out.  For example, if you have a positive charge the first thing it does is repel all the other positive charges around it and … Continue reading

Posted in -- By the Physicist, Physics | 13 Comments