[Physics] Comment

[cj at mb-soft.com]

I see more of why I do not belong in your conversations.  I had been given an extensive education in Physics, so I have some knowledge that "non-physicists" can not have.

Regarding your recent conversation, you again have confused "gravitational force" with what is popularly called "gravity".  Newton explained that when any two objects which have mass, are at a specific distance apart, they DO have a "gravitational force" on each other, per his formula which you all acknowledge.

However, the enttity which is popularly called "gravity" is more correctly called a "gravitational field" (which is technically NOT a "force") 

In addition, the "gravity" is technically also NOT precisely the quantity that the public accepts.  Because our planet has TWO rather massive objects in it, the Earth and the Moon, some more advanced Tensor Calculus needs to e used to calculate the instantaneous value of the "acceleration due to gravity".  Specifically, YOUR weight is actually measurably different at different times of the day.  At "moonrise" and "moonset", your weight is nearly entirely due to the mass of the Earth.  However, around halfway between, you actually weigh less when the Moon is nearest the zenith, and greatest when the Moon is at its nadir.  This actually greatly affects the attempts at very precisely measuring "big G" such that the dozen experimental measurements over recent decades are NOT precisely known, as those dozen calculated values for Big G are amazingly different from each other.  All those experiments  SHOULD HAVE considered these effects of the location of the Earth-Moon Barycenter, which requires that Calculus, such that the various experiments would have resulted in essentially identical mathematical results.  Even some scientists do not seem to correctly know the difference between "gravity" and "gravitational force".  Kind of sad.

It is vaguely similar to the common misunderstanding between "centripetal force" which IS a force, and "centrifugal effect" which does not actually even exist.

Carl Johnson
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