Comment by the-mitr
12 hours ago
In the Three Body Problem Trilogy by Liu Cixin some of the more advanced civilisations have the ability to change the speed of light locally with very interesting consequences for the that local space
12 hours ago
In the Three Body Problem Trilogy by Liu Cixin some of the more advanced civilisations have the ability to change the speed of light locally with very interesting consequences for the that local space
I'm being vague to avoid spoilers, but I'll just say that it serves for a very interesting meditation on the concept of loss, and has stuck with me for the 5+ years since I read the trilogy.
Same here, the quote on time passing stuck with me quite a bit.
Pedantic note: The speed of light in glass, optical fiber and water is different from vacuum (much lower). On a certain scale, humanity also knows how to locally alter the speed of light though not to this extent.
It's not actually that the speed of light in a singlemode fiber optic cable is slower, but that the photons aren't travelling in a direct path down the fiber like water down a pipe. They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable.
Basically imagine like if you wanted to walk in a straight line between two points at both ends of a empty, long, narrow rectangular warehouse, and instead of walking in a straight line from A to B, you bounced off each wall at an angle (like a pool ball ricocheting off the bumpers) to get from one end to the other. Making your cumulative distance travelled on foot much greater.
>the photons aren't travelling in a direct path down the fiber like water down a pipe. They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable.
I know there are many other mundane technologies that can be described in sci-fi-ish way, but for some reason I'm particularly amazed by fiber transmitters being compact and cheap enough to be used in mass-produced killer drones.
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> They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable
At the risk of exposing how little I remember from physics, doesn't light in a single mode fiber not bounce? (right about now I'm thinking that it's probably not great to think of photons bouncing because this is quantum level stuff, right? light is a wave, etc. gosh it's been a long time since I tried to really know any of this...)
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Light’s still slower in glass than in a vacuum, though, or it wouldn’t refract at the transition between the two.
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You're conflating two very different meanings of "the speed of light". Confusingly, "speed of light" can refer to the universal constant, c, which does not change in glass, or to the speed that light travels in a medium. Here, we're talking about c. Relativistic effects are based only on c. The Three Body Problem trilogy plot device is also about c.