Physics Question #255

Lee Riffee, a 27 year old male from the Internet asks on March 18, 1999,

With all that the U.S. military is doing by developing laser weapons as an anti-missile defense, I have been wondering if a laser beam could kill a person, as in the movie "Goldfinger". I used to work in a laser "job shop" where I witnessed multi-kilowatt carbon dioxide and Nd YAG lasers ignite and vaporize many materials. Some of the workers there had been seriously burned too. If a 5 kilowatt laser could blast a hole in a peice of plexiglass at fifteen feet in a few secs, (unfocused beam), what could a focused beam of much higher power do to a living organism (a person) assuming said victim couldn't escape the beam, as my ex-coworkers did? Or is there a laser powerful enough to burn a hole through someone instantly? I understand that whatever answer you give me would be theoretical, as I don't think anyone has ever been killed by a laser beam, according to the extensive research I have already done.

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The answer

Samuel Goldwasser answered on November 9, 2001

Daryl Crozier, a Canadian physicist at Simon Fraser University who works on super powerful beams said, "It would be impractical to kill a person with a high power laser beam. There are many easier ways of doing so."

I would add that the U.S. military is quietly working on battlefield laser weapons. They are limited from full development/deployment more from humanitarian considerations than technical (e.g., blinding is not a nice thing to do even in war!).

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