Category Archives: Physics

Q: If atoms are 99.99% space, what “kind” of space is it? Is it empty vacuum?

Physicist: This is a bit of a misnomer. When we picture an atom we usually picture the “Bohr model”: a nucleus made of a bunch of particles packed together (protons and neutrons) with other particles zipping around it (electrons).  In … Continue reading

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

Q: Is geocentrism really so wrong? Is the Sun being at the “center” (i.e. the Earth orbiting the Sun) just an arbitrary reference frame decision, and no more true than the Earth being at the center?

Physicist: When you walk around in this big crazy world, there aren’t any immediate reasons to suspect that the ground under your feet is doing anything more than sitting perfectly still (ring of fire notwithstanding).  Given that, when you look … Continue reading

Posted in -- By the Physicist, Astronomy, Experiments, Physics, Relativity | 7 Comments

Q: Why is our Moon drifting away while Mars’ moons are falling?

The original question was: I know the Moon is getting further away because tides/friction/conservation of angular momentum.  This video claims Phobos is getting closer to Mars because of tidal forces, what gives?  Obviously no oceans to drag around but what … Continue reading

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

Q: Why do we (people) wave our arms when we fall? Is it for attention?

The original question was: When I am about to fall backwards I spin my arms up over my head then down . This seems to help in preventing my fall somewhat. Is this some form of conservation of angular momentum? Physicist: Actually, … Continue reading

Posted in -- By the Physicist, Physics | 2 Comments

Q: What is the state of matter in deep space?

The original question was: What might be the state of matter in [interstellar space]. Average temperature is 2.7K , so all the gases like hydrogen, helium should be in liquid or solid state? Physicist: Matter in deep space tends to take … Continue reading

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

Q: After the heat death of the universe will anything ever happen again?

Physicist: If you wait forever, then you might see something happen.  But the more practical answer is: no. The universe does a lot of stuff (for example, whatever you did today), but literally everything that ever happens increases entropy.  In … Continue reading

Posted in -- By the Physicist, Entropy/Information, Physics | 8 Comments