Originally Posted by bright
Do you sometimes believe in gravity and sometimes you disbelieve in it too?
Lots of people would answer: "Yes I always believe in gravity" and yet lots of people would not even know what gravity really is.
Did you know that I am currently exerting a gravitational force on you? And that you are exerting a equal gravitational force on me? And that in fact you are currently exerting a gravitational force on your computer screen, your mouse pad and the stationery on your desk?
This is a necessary implication of the law of gravity - that every two objects in the universe are attracting each other with a force equal to the product of their two masses and a gravitational constant, divided by the square of the distance between them.
Most people don't know that. They just think of gravity as meaning "Things fall down, not up". Which is a rather misguided notion of what gravity is. Nevertheless they would confidently say: "Yes I always believe in gravity."