How Many Ordinary Laser Pointers Will Kill A Human Being?

How Many Ordinary Laser Pointers Will Kill A Human Being? Click To Tweet

Do you remember the evil Death Star killer machine from the movie Star Wars? Its laser beam was so powerful that it would destroy an entire planet in seconds. Well, lasers are dangerous- we are given this advice right from the early age. They shouldn’t be shone in the eyes as it could harm our vision.But, what if someone decides to make a smaller version of Death Star and creates a deadly weapon? How many ordinary laser pointers will be needed to make this weapon?

Well, before we start looking for the answers, let’s recall our high school knowledge about lasers. The word laser stands for “light amplification by stimulated emission of radiation.” It’s a single and focused beam of light that spits large amounts of energy on a single point.

The cheap laser pointer available in the marker cost less than \$2 and come with a power rating of 5-milliwatt. But, it surely is not powerful enough to kill anyone. To do this, you’ll need to combine many laser pointers and use their energy in one direction.

James Kakalios, a physics professor at the University of Minnesota and the author of The Physics of Superheroes says that making a death ray from lasers is very tough.

To kill a person, the easiest way would be to target the eye and ultimately melt the brain (excuse me if it’s too graphic).

So, to kill a person by focusing a mighty laser into someone’s eyes, how big and powerful laser pointer do you need?

Rebecca Thompson of the America Physical Society, who holds a Ph.D. in physics, has done some calculations and came to a conclusion. So, here’s her answer:

For a laser to kill someone it essentially needs to be hot enough to boil or burn the tissue. It would take about a 1kW laser to boil through someone’s eye to their brain in a reasonable amount of time, meaning they probably couldn’t get away. Each cat toy level laser pointer is roughly 5mW. It would take 200,000 laser pointers all focusing through a lens to an exact point to create a laser powerful enough to kill. Each laser pointer (assuming the ones from laser pens since the pen tip is smaller than the cat toy laser) is 5mm across. So if you had 200,000 of them they would be in a grid about 7’ x7’. To get them to focus on a single spot, though, they would need to be in a semi-circle with a radius of about 5.5’. So if you wanted to create a death ray with laser pointers, you could buy 200,000 laser pointers, mount them on a piece of a sphere with radius 5.5’, aim them all through a lens and ask your victim to sit very, very still.

Well, don’t try this at home or school.

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