The Natural Philosopher wrote:
Paul Martin wrote:
In article ,
The Natural Philosopher wrote:
Paul Martin wrote:
In article ,
Tim S wrote:

Seriously - yes, there is a mass increase.
I wind up my cuckoo clock. The driving weight (not the pendulum)
rises a metre. Has its mass increased due to the increase in
potential energy?

I think so, yes.

So you're saying that a body's rest mass increases as it leaves a
gravity well and conversely it decreases as it descends one?


Yes. I think that is so.

Well, prove it. It's your proposition and it's impossible to prove a
negative, so it's down to you.

Or rather its more like any way we have of
determining mass - by acceleration and force, will show a slightly
different result in a gravitational field.

Lets face it, mass is a concept derived from Newtonian mechanics.


No it isn't. Mass is defined as the quantity of matter in a body. That
doesn't depend on Newton or anyone else.


As is force, energy and acceleration. All Einstein really said was
that the Newtonian relationships are NOT exact. Merely good
approximations.
As I tried to point out in a rather long post yesterday, you have to
drive a stake in the ground somewhere. Newton chose to define mass as
F=mA, time iun terms of the periodic rotation of the earth about its
axis, distance in terms of things that were commonly held to not
change their length. But in fact we know that in a relativistic
universe, time, space length - all these things can vary depending
on the relative velocity of the OBSERVER.
Mas time and distance are not as invariant as Newtone supposed.
Einstein creates a new view, and relates it to the old via E=mC^2.

You can say that what he did was to leave one stake in the ground -
the invariance of one thing, that can either be seen as energy, or
mass, or some combination of the two. If you like there is a quantity
of something, that can be transformed in the mathematical sense, into
what we would recognise as energy, or what we would recognise as mass.

What he gave us was a formula that enables calculation of how energy and
mass are related _if_ a conversion between the two occurs. What he
emphatically did not say is that such conversions invariably occur whenever
energy is expended or absorbed. Your error lies in thinking that he did.