You know what is really cool? LASERS.
I put that in all caps for two reasons. One, not everyone knows (or remembers) that the word "laser" was originally an acronym. It stood for Light Amplification by Stimulated Emission of Radiation. Of course, it has become a word-- everyone knows what a laser is, and it's perfectly fine, grammatically, to write it just like that. I write it in all caps, mostly, because lasers are FREAKING COOL.
Everyone has seen, probably even used, a laser. Laser pointers are common technology (though when I was a kid and desperately wanted one, they were at least $50, I checked), CDs and DVDs are read by laser, barcodes are scanned by laser-- lasers are everywhere. The laser sight on a sniper rifle is such a well known piece of technology that a red dot appearing on someone in a movie is an instant source of tension-- that person is going to be shot!
The scientific uses for lasers are even cooler. The distance from the earth to the moon is measured by bouncing a laser off a reflector left by one of the Apollo missions. Lasers are used in microscopes to image extremely small things with great accuracy. Lasers can cut more precisely than any mechanical process. Lasers can perform surgery where no incision is necessary. They're used in spectroscopy, which is a really cool concept on its own.
So how do they work? Fairly simply, actually. You pump light into a medium that will amplify it, and then focus it out one end as a beam. Of course, it's not as easy as it sounds. You have to find the right medium so the wavelength that you want is amplified, you have to use an external power source, and so on. But really: create a tube, with mirrors on both ends, so light will reflect. Fill it with a gain medium-- it could be as simple as glass or neon, like a neon light, mixed with helium-- and then introduce a light source. For some, it could be an electrical pulse, like the helium-neon mix. For others it's a light, or a chemical reaction. It depends on what you're using as a gain medium. Make sure that one of the end mirrors is partially transparent, so the amplified light can go somewhere, and you've got a laser. Many will then put a cap on the end so that the light can only go out through a small hole, making the beam small and focused.
So, one of the really cool things about studying physics at this school is that there are a lot of opportunities to play with lasers. All of the labs on the top floor of the physics building have warnings posted on the doors about lasers. And we have some really, really cool lasers. We've got one setup that's doing microscopy-- that is using a laser as a microscope-- that literally counts photons, yielding a much clearer picture than other systems that amplify to that degree. They've got one that can give a 3 dimensional image of a fly's brain. But the coolest one is the one doing something unexpected.
They created a setup that focuses a beam in four dimensions-- that is, in the three spatial dimensions, and also in time. If you're not used to thinking of time as a dimension that's going to either sound nonsensical or extremely simple. In practice it is neither; this was quite an accomplishment. So they did what any good physicist would do with a brand new, very cool laser: they pointed it at stuff. One of the things they pointed it at was glass. Glass is an interesting thing-- it is structurally the same in all directions, because it doesn't have any sort of crystallization. It's kind of an amorphous blob, really. So, one would expect that, when carving things into it with lasers, the direction the laser was moving wouldn't matter-- the whole area touched by the laser is affected the same way. Generally, that's true. Not with this one. With this one, they get one kind of mark when moving to the left, and an entirely different kind of mark moving to the right. The conclusion they came to: their laser is somehow tiled in TIME. One side of the laser is hitting the glass slightly before the other. And they do not know why. So now there's a senior design project trying to take pictures of this phenomenon. And succeeding. At taking pictures of LASERS.
My school is awesome.
I put that in all caps for two reasons. One, not everyone knows (or remembers) that the word "laser" was originally an acronym. It stood for Light Amplification by Stimulated Emission of Radiation. Of course, it has become a word-- everyone knows what a laser is, and it's perfectly fine, grammatically, to write it just like that. I write it in all caps, mostly, because lasers are FREAKING COOL.
Everyone has seen, probably even used, a laser. Laser pointers are common technology (though when I was a kid and desperately wanted one, they were at least $50, I checked), CDs and DVDs are read by laser, barcodes are scanned by laser-- lasers are everywhere. The laser sight on a sniper rifle is such a well known piece of technology that a red dot appearing on someone in a movie is an instant source of tension-- that person is going to be shot!
The scientific uses for lasers are even cooler. The distance from the earth to the moon is measured by bouncing a laser off a reflector left by one of the Apollo missions. Lasers are used in microscopes to image extremely small things with great accuracy. Lasers can cut more precisely than any mechanical process. Lasers can perform surgery where no incision is necessary. They're used in spectroscopy, which is a really cool concept on its own.
So how do they work? Fairly simply, actually. You pump light into a medium that will amplify it, and then focus it out one end as a beam. Of course, it's not as easy as it sounds. You have to find the right medium so the wavelength that you want is amplified, you have to use an external power source, and so on. But really: create a tube, with mirrors on both ends, so light will reflect. Fill it with a gain medium-- it could be as simple as glass or neon, like a neon light, mixed with helium-- and then introduce a light source. For some, it could be an electrical pulse, like the helium-neon mix. For others it's a light, or a chemical reaction. It depends on what you're using as a gain medium. Make sure that one of the end mirrors is partially transparent, so the amplified light can go somewhere, and you've got a laser. Many will then put a cap on the end so that the light can only go out through a small hole, making the beam small and focused.
So, one of the really cool things about studying physics at this school is that there are a lot of opportunities to play with lasers. All of the labs on the top floor of the physics building have warnings posted on the doors about lasers. And we have some really, really cool lasers. We've got one setup that's doing microscopy-- that is using a laser as a microscope-- that literally counts photons, yielding a much clearer picture than other systems that amplify to that degree. They've got one that can give a 3 dimensional image of a fly's brain. But the coolest one is the one doing something unexpected.
They created a setup that focuses a beam in four dimensions-- that is, in the three spatial dimensions, and also in time. If you're not used to thinking of time as a dimension that's going to either sound nonsensical or extremely simple. In practice it is neither; this was quite an accomplishment. So they did what any good physicist would do with a brand new, very cool laser: they pointed it at stuff. One of the things they pointed it at was glass. Glass is an interesting thing-- it is structurally the same in all directions, because it doesn't have any sort of crystallization. It's kind of an amorphous blob, really. So, one would expect that, when carving things into it with lasers, the direction the laser was moving wouldn't matter-- the whole area touched by the laser is affected the same way. Generally, that's true. Not with this one. With this one, they get one kind of mark when moving to the left, and an entirely different kind of mark moving to the right. The conclusion they came to: their laser is somehow tiled in TIME. One side of the laser is hitting the glass slightly before the other. And they do not know why. So now there's a senior design project trying to take pictures of this phenomenon. And succeeding. At taking pictures of LASERS.
My school is awesome.
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