Proving H.G. Wells’ physics wrong

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This is something that has bothered me for a long time. In “The First Men in the Moon”, an inventor named Cavor creates a metal alloy that is opaque to gravity. When the alloy is finished, the roof flies off the laboratory because the air above it becomes weightless and shoots off into space. We are told that if the sheet of Cavorite (as the gravity-blocking substance is called) hadn’t likewise risen into the air and been catapulted off the Earth, the atmosphere would continue siphoning off into space until the whole planet would be asphyxiated.

This doomsday scenario fascinated me when I first read the novel as a kid, but I think it is wrong. Imagine yourself a molecule of air several hundred feet up. Then the furnace-sized sheet of Cavorite would seem to cover only a very small part of the Earth’s surface, while all the rest of the planet would continue to attract the molecule. And the same applies to molecules not directly above the sheet (see diagram below) - part of the planet is blocked off from them, though as you approach the horizon, the gravity-lessening effect of the Cavorite becomes smaller and smaller.



Of course right above the sheet, the molecules will be completely weightless, and a low-pressure zone will result such as we find above an airplane wing, but the higher up you get, the heavier the air will be, pressing down open the weightless air below. The way I see it, there should be no effect on the atmosphere at all. As far as solid objects go, if you place an object onto the sheet of Cavorite, it will jerk up into the air due to the centrifugal force of the rotating Earth, but stop and hover as soon as the gravity exerted by the uncovered surface around the sheet is exactly equal to the centrifugal force. Can anyone with a more extensive knowledge of physics confirm or deny my conclusions?

Your analysis might be correct if gravity were a force, subject to some form of scattering. However, at least in Newtonian and Einsteinian physics, gravity is a field effect, a warping of space-time caused by the presence of mass. Objects are attracted to one another - we are held to the curved surface of the Earth because we are pulled toward the planet's center of mass. Were there something capable of canceling the field effect in a line straight up, it would continue to be canceled in that line, right on out until it wouldn't matter any more (because the gravity being canceled would be too weak to be felt anyway).

However, it does seem likely that in the ensuing inverted supertornado, the piece of Cavorite would be tossed about, moving its focus of effect and disrupting the whole atmospheric-evacuation process rather quickly. Mr Wells was, of course, unfamiliar with the sheer power of a tornado - not a lot of those in England, and he wasn't really well enough to travel about much.

Current thinking would imply that gravity is the result of mass warping the fabric of space-time and not a result of "gravitons". However, even if there were gravitons, that material would only block a small surface area of the sphere of the Earth. The net effect would still be downward gravitation, just not close to the material.

Gravity works as if matter pulled at matter, but I believe that it is a curvature of space-time in a time direction. Such a "shielding effect" could do anything and I can't set restrictions on it.

I think actually the sheet of Cavorite would act the same way you see objects behave in zero gravity (which Wells couldn't have seen, since he died in the 30s... However, if you pushed it upswards, it would just continue to drift, pushed by winds, heat, etc., until eventually it would probably just drift away. (since it, and the entire Earth are moving at the same speed, it shouldn't go flying anywhere)

If it was a constant effect (a native property) of the material, that is.

If it required some sort of energy (electrical, whatever), it would revert to normal mass and gravitational attraction, and lawd hep the poor fool under it when that happened.

There would have to be some force remaining in place for a tornado like that. As the source of the gravitational disturbance, the effect would be strongest at the point where the Cavorite was.

Think of it like you would a radioactive material, only with gravity instead.

Of course, I never took physics (which is the mathematical description of life, the universe, and everything...


btw - I think the literary term for what Welles was talking about is called a deus ex machina...