**Ask a monkey a physics question thread**

[Eric]

Sure.


I already knew that tetrachromacy was moderately common in women and not known to exist in men. I didn't know that it's rare for a person with 4 cones to have the "extra" cones be active.

Yeah, that article did a nice job explaining the fact that there is a subset of women in the 4 cone group where the extra cone is active.


On another note, we were watching the Vancouver English Bay fireworks show last night from a distance. As one would think, the light got to us very quickly but the sound waves took longer. It almost sounded like there were two explosions each time, one delayed a little bit from the light and one delayed even more.


We use one word for thunder and another for lightning but they both come from the same event. What are some other examples in the universe where we perceive things to be different when they come from the same event? I guess an obvious answer would be space-time but there are probably quite a few others...

[MadMojoMonkey]

It almost sounded like there were two explosions each time, one delayed a little bit from the light and one delayed even more.

This is almost certainly an echo.

We use one word for thunder and another for lightning but they both come from the same event. What are some other examples in the universe where we perceive things to be different when they come from the same event? I guess an obvious answer would be space-time but there are probably quite a few others...

Whether an object is moving or stationary is a matter of perspective.

Whether a field is electric or magnetic or a combination of both can be a matter of perspective for the above reason, applied to electric charges.

E.g. if you are holding a charged object and you drive past me... to me, your object is a moving charge, hence it creates a magnetic field. To you, it is a stationary charge, hence it creates no magnetic field. We both measure the same total energy in the electromagnetic fields.

I'm sure there are plenty of other things. It is frequently our description (expectation) of a thing or phenomenon which characterizes what we think we perceive.