On 2008-02-29, Erik Max Francis <max@[EMAIL PROTECTED]
> wrote:
> The potential energy is not in the field itself, nor does the
> strength of the field change based on the arrangement of objects
> within it.
Electromagnetic fields do have energy, and the change in energy of a
charged object can be understood in terms of energy transfer between
the field and the object.
In the weak-field limit a similar property can be defined for
gravitational fields (with the field energy density being negative),
but it really doesn't work in general.
> The strength of a gravitational field depends on the mass of the
> gravitating body; for the gravitational field to "become more
> intense," it would have to increase in mass, which is clearly
> ludicrous.
An object falls to Earth. It gains in kinetic energy, and its mass
now adds to Earth's mass, intensifying the field. Not as ludicrous as
you try to make it sound.
- Tim
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