How can i check and calculate if a certain vacuum pump can hold an object that weights X kg? By "hold" I mean not let that object fall to the floor due to gravity
Is it by gravity? How could gravity produce a repulsive force?
I see many references to the speed of light in a vacuum implying that it is only truly a constant measurement in a vacuum. I can live with that, but what kind of vacuum? Are we still talking about ...
How can one show from General Relativity that gravity is attractive force, and under which conditions it becomes repulsive, also why positive energy vacuum drives repulsive gravity?