Creating armor that renders a soldier invisible. Stimulating the brain to suppress sleep for days. Arming sharks with chemical implants and cameras to work as spies.
This year the Pentagon will spend $78 billion — about half of all government research and development dollars — on a variety of projects, according to the American Association for the Advancement for Science (AAAS).
The vast majority - about $68 billion - goes to traditional spending, like weapons development and space systems. But some fringe research mimics the best of science fiction.
There seems to be no failure of imagination in advancing warfare, but some experts fear these farfetched projects show a little too much imagination.
Just this month, the government confirmed that an Ohio Air Force laboratory had asked for $7.5 million to build a nonlethal "gay bomb," a weapon that would encourage enemies to make love, not war. The weapon would use strong aphrodisiacs to make enemy troops so sexually attracted to each other that they'd lose interest in fighting.
Last year, scientists at Boston University developed brain implants that could steer sharklike dog fish with a phantom odor.
Just three years ago, the military funded a specious study of psychic teleportation, according to the Federation of American Scientists. An 88-page report prepared by the Air Force Research Lab contended that moving through mind powers is "quite real and can be controlled."
"The military has a lot of crazy ideas," said Noah Shactman, editor of the Wired blog Danger Room. "But it's hard to turn these ideas into action."
In her book "Imaginary Weapons," military expert Sharon Weinberger writes that the federal government is spending taxpayer money on war technology at a pace of about $50,000 per second.
"If you don't support long-term investment in funding risky science and technology, you won't get breakthroughs," Weinberger told ABC News.
But investing in wacky weaponry can also have the opposite effect.
"There is more pressure to fund fringy things, much the same way a bankrupted person will be tempted to play the lottery," said Weinberger. "There is the risk that agencies starved of funding will invest in schemes that promise high payoff, but aren't a sound investment," she added.
Scientists are exploring beamed speaker systems that only one person can hear and foam that makes the enemy slip and fall. And they are using something akin to microwaves to penetrate the skin and make the enemy feel as if they're on fire, according to Shactman.
The controversial hafnium bomb — originally a $30 million project to build a nuclear grenade — never got off the ground. The idea was either "the beginning of a new superbomb, or the biggest fizzle since cold fusion," Weinberg wrote in a 1998 article in the Washington Post.
"When it comes to Pentagon funding it's important that imagination is tempered by two things: the laws of nature and the laws of the budget," said Weinberger.
Some of the military's most fantastical ideas come from the Defense Advanced Research Projects Agency (DARPA). The $3 billion agency — which laid the foundation for today's Internet — says it is the "technological engine" for the Department of Defense.