I believe I have been holding a misconception for a long time, surely dating back to some sketchy science fiction. I would like to verify what truth there is in this. Say you had person $A$ floating in a vacuum, and an exact copy of person $A$ but made out of antimatter, call them person $B$, was...

I was cycling with my little sister who was a little upset by the fact that I would arrive first at the end of a small bridge when we both started from the middle (where the plane is not inclined). Once we arrived home our dad told her that there was nothing to complain about as I am heavier than...

I want to know why every question starts with an assumption that a rod, cyliner, plane, etc. is very long.

In my textbooks it is written that when an object is kept at focus, its image is formed at infinity and is real. But how is this possible because parallel lines never meet and it is necessary for rays to meet to form image. Furthermore on youtube there are videos where the object is kept at focus...