The existence of transient mass fluctuations in objects subjected to large accelerations and rapid changes in acceleration depends upon "Mach's principle" and some peculiarities of "radiation reaction" forces. Mach's principle is the assertion that the physical origin of all inertial reaction forces is an interaction of the object with chiefly the most distant matter in the universe. (Inertial reaction forces are those things that push back on you when you push on stuff.) Radiation reaction forces are experienced by charged objects as they "launch" energy in the form of radiation when they are accelerated by external forces. (These are recoil forces, like those experienced when "launching" bullets out of a gun in your hand.) When examined, the origin of inertia and radiation reaction turn out to have some very strange consequences, notwithstanding that no "new physics" is involved. These ideas are explored in the following material.

The main document is kept free of detailed arguments and mathematics so that the conceptual argument is relatively unencumbered by technical details. It is written in interrogatory style to directly address questions you may have about this stuff. Links to more detailed discussions attended by some math are provided for several of the key ideas. I have tried to keep the exposition everywhere one that can be followed by anyone with only a modest technical background.


What is the origin of inertia?

Does the gravitational "field" of general relativity theory that produces inertial reaction forces have a real existence independent of the distant matter that creates it?

But radiative interactions propagate at the speed of light. Inertial reaction forces, however, are instantaneous upon the application of "external" forces. How can a radiative interaction that propagates at the speed of light be responsible for a seemingly instantaneous interaction between a local object and the most distant matter in the universe?

So what? Why does this have anything to do with radiation reaction and transient mass fluctuations?

But electromagnetic radiation reaction forces in normal circumstances are miniscule, and gravity is a much weaker force than electromagnetism. So how can that be right?

Granting that inertial reaction forces may be like electromagnetic radiation reaction forces, what is it about radiation reaction that makes it of interest in the business of transient mass fluctuations?

Well, what about gravity?

How do you get these effects (other than finding them in Nordtvedt's paper)?

If you're unconvinced that transient mass fluctuations might really occur, you might ask: Is there any way to get rid of these pesky transient mass fluctuations?

Surely you're kidding. Can this stuff really be right?

If you've made it this far and want more details:

By the way, a note on these documents: There's presently no good format for displaying documents directly in web browsers. In the future that may change, but for now all equations in these documents are displayed as numerous inline gif Images. As a result they may not line up with the rest of the text very well, and in short appear a little funky. Sorry about that, but it's the best that could be done.

Copyright © 1998, James F. Woodward. This work, whole or in part, may not be reproduced by any means for material or financial gain without the written permission of the author.