I want to build a character that can control a light source's brightness in different ways. I want to see if instead of proportional to $1/r^2$, my light and darkness controlling character could make it proportional to $r^2$?

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    $\begingroup$ The problem is that light is tied into fundamental physics at a very intricate level. You might check out this question. That's about inverse linear rather than direct square, but it should give an idea of what kinds of physics changes would happen. It would be profoundly weird. $\endgroup$
    – Cadence
    Jul 17 '18 at 4:16
  • $\begingroup$ Also worth noting; "light" is just a section of the electromagnetic spectrum. I suspect that control over the "brightness" of x-ray or gamma sources would be far more useful than visible light. $\endgroup$
    – jdunlop
    Jul 17 '18 at 4:22
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    $\begingroup$ So you want a light that grows stronger as it propagates? $\endgroup$
    – L.Dutch
    Jul 17 '18 at 5:11
  • $\begingroup$ @L.Dutch Now that would be a useful super-power. Effectively amplifying low-light sources into blindingly bright ones at a distance. $\endgroup$
    – a4android
    Jul 17 '18 at 5:22
  • $\begingroup$ @Cadence I dont think that would apply. The question mentioned is about a whole universe rather than a local magic phenomenon caused by the hero (villain?). As the control is magic, the OP could simply ignore the consequences for local space or still apply the conservation of energy law by having energy escape diffferently based on the magic of controlling light. $\endgroup$
    – Demigan
    Jul 17 '18 at 6:19

What you describe is roughly what happens in so called gaining medium.

Normally, as light propagates in any medium, gets attenuated according to the law $I(x)=I_0e^{-\alpha x}$, where $\alpha$ is called absorption coefficient.

In a gaining medium $\alpha$ is negative, resulting in light being amplified as it travels through the medium. This is used in laser cavities and light amplifiers.

To generate a gaining medium one needs to achieve population inversion in the medium, or, in layman terms, there need to be more excited than neutral atoms in that medium. I.e. RF excited CO2 can act as amplifier for infrared light.

So, if your guy is able to induce inversion population, he can achieve what you want. Oh, mind that the exponential grows even more than the square...

  • $\begingroup$ Yes. This kinda answers it. I want my photokinetic character to be able change it from 1/r to 1/r, 1/r-² or even 1/r-³. The character I'm building can use light for both illusory and destructive effects. What I meant by inverse square was the opposite of how light usually decays from a source. $\endgroup$
    – shawnny321
    Jul 18 '18 at 5:12
  • $\begingroup$ @shawnny321, please clarify it in your question. As you see, it has been put on hold for this $\endgroup$
    – L.Dutch
    Jul 18 '18 at 5:37

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