How could a laser kill someone

How many laser pointers would it take? to kill a man & quest;

Everyone doesn't know laser pointers shine in your eyes. You are damaging your vision! (Main emphasis couldsince your blinking eye reflex would probably protect your retina.) But what if you were an evil villain determined to make a death ray? How many laser pointers would it take to create a deadly weapon?

That sounds like a crazy question because it is. Laser pointers are purposely designed to be safe for everyday use. It is common knowledge that staring at a laser can be dangerous. But the question of how many laser pointers it would take to deliver a fatal blow is inevitably the question of how deeply ingrained any given laser pointer is.

A quick primer on laser

Before we dig into the gruesome mystery of how to kill a person with a laser dot (or a whole lot of it) let's again ask a question from high school physics: what is a laser?

The word laser is actually an abbreviation for "light amplification through stimulated emission of radiation." In plain English, a laser is a single beam of light, a series of photons in the same direction. (Usually light shoots out in all directions) High-powered lasers deposit large amounts of energy on a focused point, producing heat and, in extreme cases, malignant burns. The United States Navy, for example, has a laser that is powerful enough to blow a drone straight out of the sky.

The strength of each laser - and therefore danger - is determined by the number of outputs, which are usually measured in milliwatts of electricity. In the United States, the Food and Drug Administration (FDA), all products must be 5 milliwatts or less, and some cheap laser pointers have an output power of less than 1 milliwatt. But you can also google "cheap laser pointers" and find a 5 milliwatt device for less than $ 2. Since these laser pointers come from faraway foreign countries, they are often missing hazard safety stickers, required by the FDA. Sometimes they even lack a critical protective shield to protect dangerous infrared light from escaping the pointer.

The dangers of infrared light alone are hardly fatal at this level. Infrared light is most dangerous because it is invisible so your blink reflex won't kick your eyes before your retina starts to burn. Even still that burn would damage your vision, but it wouldn't kill you. To do this, you would need a laser much more powerful than 5 milliwatts.

Or would you?

Now let's get down to business

The crazy thing about lasers is that the carriers of multiple low-power lasers focus and create a single powerful beam. However, this is not an easy task. Multiple laser pointers would need to be perfectly focused through a lens that would send the combined energy towards the target. It's kind of like the "don't cross the bar" trick by Ghostbusters but much more scientific.

If - as our morbid target requires - you wanted to kill someone, the easiest way would be to shoot her right in the eyes. Powerful enough, lasers could cut through the retina and burn through the person's brain tissue. But it would take a while and you would have to focus the laser on a specific point. So basically you would have to buckle the person down or immobilize them in some way.

This gruesome scene is hardly the Death Ray type of solution you see in cartoons. The time factor is particularly difficult given the simple physics of the situation. James Kakalios, professor of physics at the University of Minnesota and the author of The physics of superheroessays that building a death ray from laser - and even a death ray in general - is pretty darn hard.

"To blast a hole in something, you have to deposit more energy, in a short time, faster than the energy path that can be dissipated," explains Kakalios. "If you can do this then you can overwhelm the bonds that hold the material together and the atoms fly away." But if the excess energy removed from the laser can be done as heat, then all you have to do is warm up the material. "

But what if you warm up brain matter? It melts. Considering the fact that we're talking about cobbling together a powerful laser from multiple laser pointers, it probably still takes a decent amount of time to burn through someone's brain.

Laser blasting heads is a burgeoning technique in neuroscience. In small doses, rays of light from lasers can actually trigger brain activity and even heal pain. Tim Spellman, a postdoctoral fellow in neuroscience at Columbia University, spends his days shooting laser mouse brains for the sake of medical research. However, he is also well aware that the continued presence of high-powered lasers could do significant brain damage.

"Basically, you're going to have to heat the tissue to burn enough fat since the brain is mostly fat - that's somewhere between 300 to 500 degrees," Spellman said in an email. "But how quickly that happens in an actual human brain is something you don't know until you try. But my guess is 10 seconds or even minutes."

How many laser pointers would it take?

So we decided that laser pointers could be focused through a lens to create a more powerful beam given the right circumstances. We have also found that a high-powered laser could burn through a person's eyes and, given a sufficiently long period of time, their brain could melt. But just how big would this laser pointer rig have to be?

Pretty big, according to Rebecca Thompson of the American Physical Society. When we asked Thompson who had a Ph.D. in physics from the University of Texas, the morbid question of death and laser pointer, she keeps crunching some numbers and reviewing her work. It is worth quoting her answer in detail:

For a laser to kill someone it must essentially be hot enough to boil or burn the tissue. It took about a 1kW laser to cook through someone's eyes in front of their brain in a reasonable amount of time, meaning they probably couldn't get through. Each cat toy-level laser pointer is about 5 MW. It took 200,000 laser pointers, all focusing through a lens on an exact point to create a laser powerful enough to kill. Each laser pointer (assuming those made from laser pointers since the pen tip is smaller than the cat toy laser) is 5mm in diameter. So if you had 200,000 of them they would be about 7 "x 7" in a grid. Call them to focus on a single point; however, they must be in a semicircle 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, glue them to a piece of a 5.5 'radius ball, aim them all through a lens and ask your victim very, very quietly to sit.

And how exactly would the recording have to be?

Focusing through the eye and the brain would be the easiest, for sure, but it would take a fairly accurate hit to make sure the person died. The brain stem is right there, but it should burn right through.

So there you have it. Just mount 200,000 laser pointers on a sphere the size of a small car, concentrate their rays through a special lens and point precisely focused on an immobilized person's brain stem. And you've got a laser pointer powered death ray yourself.

Do not try this at home.

Illustration by Jim Cooke / Photo via US Navy / Wikipedia

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