Re: CONSERVATION OF ENERGY

[Leigh Palmer <palmer@sfu.ca>]

> I believe I see the basis of Leigh's difficulty now; it is not difficult to
> explain - in fact if I continue with the dictionary definition, that may be
> sufficient:

*I* have a difficulty? The impediment, Sir, is on the other foot!

Jim Green is correct in being astonished at a physicist consulting
a dictionary for the meaning of "energy". Much as the dictionary
tries to qualify the definition it still falls far short of being
complete. I'll give you an example of a closed system having a
conventionally recognized energy. It's part of Ludwik's system, by
chance.

I offer you one block of iron at zero pressure and absolute zero.
Most of us here will believe that the energy of this system is
given by E=mc^2, a traditional form. Now, please get some work
out of it.

No, you're not permitted to lower the block into a gravitational
well. Work derived by that artifice would involve a larger system
including the source of the gravitational field. You get the idea.

Having just made this question up on the spot I can think of only
one solution myself. Perhaps discussion of it will be interesting.

> I wanted to end by quoting Feynman's 'parable of the blocks' (Vol 1, para
> 4-1) but I find it difficult to extract the essence of Leigh's sense of
> perfect explanation.
>
> Perhaps it lies here:
> "Energy has a large number of different forms...kinetic energy, heat energy...
> ...nuclear energy, mass energy."
> "It is important to realise that in physics today, we have no knowledge of
> what energy is."

That last statement refers to the kind of energy that is "pure",
energy that is not the outcome of some calculation done on the
parameters of a system. Pure energy is unknown. In terms of the
parable the quotation is "there are no blocks." Those who have
not done so should read the entire piece; a snippet won't do.

Leigh