LASERS!?

Let me start this post by stating the obvious: lasers are awesome. However, this is not entirely due to the pioneering work of Dr. Evil.

Though one has to recognize his work.

Other than their use in popular fiction, lasers have a startling amount of applications in the real world, too, from running your CD player, to creating microchips, to wreaking havoc and destruction, to malfunctioning during PowerPoint presentations.

So… what are lasers, anyway? The simple answer: photons. The more complicated answer: When an energy source is pumped into an atom, the electrons that the atom holds get ‘excited’. This makes them jump up in energy level; the electrons physically jump to a place farther away from the atom’s nucleus. Eventually, the electron tries to release that energy, in order to get back to its original state (or something close to it). This release of energy is contained within a photon, a massless particle. This photon has a wavelength proportional to the jump of the electron, which gives it a specific color to the human eye.

This diagram may or may not be helpful.

In the case of a laser, these photons become trapped between two mirrors, one of which is only partially reflective. Being trapped in this tube makes the photons hit more and more atoms, which in turn make the atoms’ electrons jump, which in turn creates more photons. When enough photons are made (which takes a grand total of a couple of nanoseconds) they are able to filter out through the partially reflective side in a direct stream of photons.  

It looks kind of like this. 

What makes lasers different from, say, a light bulb, is that lasers:

1. Consist of entirely the same photon wavelength. It’s entirely one color, not a blend.
2. Have one direction. The way a laser tube is designed makes it impossible for a photon to come out angled. Of course, once the stream of photons hits anything, like air, it can become dispersed. 

Making the photons more energetic, or shooting more photons out, makes the laser ‘stronger’. Upping the energy of a laser is responsible for the different colors in your laser pointer: red is the lowest-energy color, and so is the easiest to manufacture.

As mentioned before, lasers are used for hundreds of thousands of very practical applications. If you were trying to make that lightsaber you’ve wanted for so long, though, you may find that you’re out of luck. Unlike a lightsaber, a real laser has no magic length at which the beam stops; a laser sword would go on forever, which would make it more like a blaster. And, according to most sources, lightsabers are actually made of plasma, not light, making them much more… physical.

Not to worry, though. Though the laser has limited use as a weapon, they’re still going strong when it comes to scientific advancement. Britain is hard at working making the world’s biggest laser, one that could capture virtual particles in the vacuum of space. Completing such a project would be quite a feat. 

It looks kind of like this. 

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If you still want that lightsaber, Michio Kaku is here to help: How to Build a Lightsaber. Of course, if you want to go a cheaper route, you could always make your own.