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Even those sleeping in the countryside have means to limit the amount of external light seeping in their dwellings. The amount of people sleeping en plen air is very limited. … Therefore your new light casting moon would have little to no effect. …

This can be translated to blue traffic light in English. …

Take a credit card, or something else with an hologram in it, and put it under the sun. You see the hologram without needing a power supply for the object, because the hologram has already been realis …

The infrared spectrum or the visible spectrum, just to name two, are just convenient anthropocentric conventions, not a reality set in stone. If you asked a bee what is for them the visible spectrum, …

Light can converge and diverge, as anybody who uses lenses can tell you. Laser is not different, it can converge or diverge, providing that a suitable lens is available. …

An holographic projection appears like a real 3D object, but it is made only of light The feeling of touch is induced by pressure waves, and it requires only the pressure waves to be triggered, not the … holographic image An holographic projection, bein made of light, can only kill with it. …

They can use stars to tell the North, and then the horizon line, recognizable because it gives a sharp separation between starry sky and dark ground, to recognize landmarks which can act as reference …

That not enough to shine any useful light, even holding it very close to the object you want to illuminate. …

Dark matter is responsible for temporal refraction of photons: while for ordinary refraction we see the beam of light slightly changing its direction of propagation in space, for temporal refraction we … The disappearance would account for why the dark matter is "dark": any light we shine on it will be visible somewhere in the past or the future, not in the time we are doing it. …

Something akin to snow blindness, or photokeratitis, can explain this Photokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ult …

Since you ask about avoiding future supernova risks, let me reuse my answer to this question. The question was about the safe distance from a supernova for a Dyson sphere, but since the estimate I do …

Consider that it will be way closer than Venus is to Earth, and stay assured that it will be enough of a light source at night. … It's called Earthshine and it's caused by the Moon reflecting back the sun light cast on it by the lit side of Earth. (image source) …

When we observe something, light shines on it and it's sent back to us. That interaction is very fast, but even if that time was altered it would not affect the light emitted back. …

So Saturn reflects about 3 times more light the Moon per unit surface. … If instead it orbits at the distance of Saturn, we drop into the calculation the value of the solar constant at Saturn, which is 1.1% of Earth's one, meaning that Saturn gets that amount of light with …

beyond generic statement like "talcum is highly reflective" or non normalized spectra, like this one If we make an assumption that talc is from 2 to 3 times more effective than regolith at scattering light … , we get that the talc covered lunar surface would roughly reflect back a similar proportion of light. …