Shrink ray

In science fiction, a shrink ray is any device which uses energy to reduce the physical size of matter. Many are also capable of enlarging items as well.

Science fiction writer and polymath Isaac Asimov wrote:

Miniaturization doesn't actually make sense unless you miniaturize the very atoms of which matter is composed. Otherwise a tiny brain in a man the size of an insect, composed of normal atoms, is composed of too few atoms for the miniaturized man to be any more intelligent than the ant. Also, miniaturizing atoms is impossible according to the rules of quantum mechanics.

Depending on how those atoms were supposed to have been miniaturized, the man might or might not also weigh as much as he originally had; an observation that has been used to various effect over the years that Henry Pym has been featuring in comic books.

The problems of the miniaturized human do not stop there, however. Basic geometry governs such things as the relationship between cross-section, volume, and surface area. The miniature human being may be able to leap several times his own height, but he will also be shivering like a toy dog or a hairless cat outside in the middle of the night; and for much the same reason. It may be impossible for a one-inch high human to kill themselves in a fall of any conceivable height, but they may be able to drown themselves with a single drop of water.

The term "grocery shrink ray" has been used to describe a manufacturer decreasing the amount of product in a package while keeping the package price the same, as a scheme to implement a hidden price increase.

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Wikipedia