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Questions tagged [light]

For questions concerning electromagnetic radiation in the visible spectrum.

14
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5answers
4k views

Using light as a barrier to block people without grilling them

We know that light exerts pressure upon matter. I'm imagining a hallway where an intense light source on one end shines towards the other end. The goal is to have the beam of light exert so much ...
2
votes
2answers
124 views

Mechanism to slow down the light emitted by an object such that it will result in inaccurate position of the object to the observer?

Let's say that there are two people named S and C. They are not far apart; less than 10 meters. Let's also assume the scenario takes place in late evening or in the night, for simplicity. Normally ...
13
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3answers
2k views

Is it really possible to see across a ringworld? [duplicate]

Almost all illustrations of ringworlds that I've come across tend to show off the shape of the ringworld from the surface. This doesn't seem realistic to me, because the ringworld's radius would ...
22
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13answers
4k views

Always a full Moon for the Emperor - Can this be achieved with solar panels and LEDs?

The Emperor of the World wants there always to be a full moon. His Scientific Advisor (the SA) comes up with a plan. He plans to cost out the venture, hand it over to the Keeper of the Treasury who ...
4
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4answers
215 views

Purple plants on a planet orbiting a green star?

Before I continue, yes, green stars don't really exist visually. Although stars like the Sun are green stars, they appear white (and are known as yellow dwarfs) because it doesn't only emit green ...
8
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3answers
426 views

The Complicated Nature of Photokinesis

I am currently working an a magic system that involves Photokinesis. However, I am having difficulty understanding its limits and its capabilities. Visual example The best definition for this type ...
12
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1answer
159 views

Would Rayleigh scattering (blue skies) be noticeable in an O'Neill cylinder?

In my story there is a full size (Island Three) O'Neill cylinder, 5 miles in diameter and 20 miles long. It doesn't have windows, but is lit internally down the center of the cylinder with a 20 mile ...
5
votes
3answers
147 views

Determining the energy efficiency of a Light Wand

So, I'm working out some of the types of wands people can purchase in my flintlock fantasy setting, and I'm having an issue with one of them. Before I get to that, let me explain how Magic in my ...
22
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6answers
5k views

What does a solid, 1 mile diameter subterranean glass sphere look like?

There is a solid glass sphere that is 1 mile in diameter. It is completely covered in dirt and rock, except for one small room that is built adjacent to the sphere. One of the four walls of this ...
35
votes
6answers
5k views

What light colors/bulbs should be used inside a spaceship?

I've noticed in recent scifi shows/movies such as the Expanse or Star Trek that the lighting inside spaceships have two characteristics: Punishingly blue lighting Dark/dimmed miscellaneous lighting ...
-3
votes
1answer
203 views

What if light didn't decay by a square law, but instead by an INVERSE square? [closed]

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 ...
6
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2answers
116 views

Vision on Titan/Early Earth and the technicalities of a creature seeing in near infrared

I am trying to develop an alien species that could live on Titan and at first I supposed it would be easy with the species being able to use yellow, red and near-infrared wavelengths of light to see. ...
2
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2answers
112 views

Albedo of a planet like Crait

If a planet like Crait existed and was covered by (mostly) white sand, what would its average albedo be? Crait is a planet from Star Wars that has a thin layer of white salt on its surface.
2
votes
1answer
133 views

How bright does this planet look from its neighboring planet?

I have two planets that share an orbit around a pair of stars at a distance of 2.05 Earth-AU from the Barycenter of those two stars. (I can provide more details about the two stars, if needed) Using ...
18
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5answers
3k views

Can visible light be blocked while still allowing for light for plants to survive to pass through?

What I'm thinking for this question is that some kind of filter is put around the sun by aliens that prevents some kinds of solar energy from passing through but allows other types. Like if it ...
10
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4answers
2k views

How do vampires react to passive UV light sources?

Certain fantasy creatures are extremely sensitive to concentrated UV light. eg modern vampires. They either slowly or rapidly burn up in-front of you when exposed to direct sunlight or modern high ...
4
votes
2answers
184 views

Is it possible for a planet with life to orbit around a white hole?

I have created a planet called Betiler. I don't want Betiler to be in a classic space system like a star and some planets. So I put it around a white hole called Phulom. In my world, wormhole doesn't ...
5
votes
3answers
225 views

What would be easy or difficult to do with the power to directly control light?

Without going into too much detail, let's say someone has a superpower which gives them "control" over actual, physical light: Photons, electromagnetic radiation, what have you. This power requires ...
5
votes
1answer
117 views

Can I see my secondary star?

I have a binary star system and have come up with some stats for it. My primary star is an F-type, with a mass of 1.3 sols and a luminosity of 2.197 sols. My secondary star is a K-type, with a mass ...
25
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16answers
6k views

How to make sure humans do not know the meteorological phenomenon rainbow?

You've got to love the rainbow, it's an awesome sight. But I don't want humans to have the pleasure of seeing the rainbow. What change to the earth, atmosphere and so on, is needed so that humans ...
6
votes
1answer
303 views

Could a light mage microwave your face?

First post, so I’d appreciate suggestions and help on how to make this question better. Question Suppose there’s a sorcerer with power over light. He can use these abilities to perform all the ...
26
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5answers
5k views

How reflective is blood?

If you were on a raft in say, an ocean of blood, and it was very still, would you be able to see the stars of the night sky reflected in it? Would you be able to see your own reflection? How far down ...
9
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2answers
515 views

How would sunlight work in the area of shared atmosphere of a Rocheworld?

(See diagram) Presupposing that a Rocheworld can even exist... I imagine that sunlight would work more or less the same in the atmosphere of any part of an Earth like planet that was tidally locked ...
-2
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1answer
193 views

How would computer monitors work if we could sense the frequency of light?

Human's abilities to perceive light is quite limited. Essentially, we have three type of light sensors that each give a linear signal, and if two different light sources give the same signals they ...
3
votes
2answers
158 views

How to make glowing rain/mist?

So I've been playing Xenoblade Chronicles 2 and one of the effects that is used through the game (and the series really) is that ether (the game's version of mana) can often be seen floating in the ...
5
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3answers
527 views

A double-bright Moon and plant growth

It's Earth and the moon with all parameters as they are in real life with one exception, the moon is twice as reflective as usual. Instead of an albedo of 0.12, the moon has an albedo of 0.24. This ...
-6
votes
4answers
207 views

The Planetary Light Curve

I know that light can be affected by gravity. But what if there was a planet where if you shone a light in a direction and it could hit your back. I'm talking about a planet where light is bent around ...
18
votes
9answers
724 views

Compressed air lighting?

So I've got this civilization that doesn't have electricity, but does have municipal power distribution via compressed air lines. Now, you can do a lot of useful things with compressed air. Even in ...
1
vote
1answer
81 views

What would be more effective for a Shkadov thruster? An entirely white one or a mirror one? [closed]

A Shkadov thruster is a megastructure which reflects all light from a star in a given direction. What reflects more radiation, a white or a mirrored surface?
6
votes
1answer
97 views

Defining the perceived appearance of a moon from a planetary surface

I have a homebrew setting with a moon that has some specific features orbiting an Earth sized planet, and I'm trying to find out how these features would affect how the moon looks from the surface of ...
15
votes
5answers
2k views

How would a microscopic organism create kilometre long fibre optic cables from ice

My story premise is that a human expedition to Europa has happened and the travellers have tunnelled through the ice and formed a colony in the ocean. When they breached into the ocean, they ...
7
votes
5answers
123 views

What traits/actions must give away a light-sensitive out-dimensioner? [closed]

There is a sub-dimension of this reality where a race of humanoid people lives in very low light. Their race has done so for hundreds of years - everyone there has no experience of being outside their ...
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1answer
249 views

How would vision be distorted if gravity was 178 000 times higher on earth's surface? [closed]

Ignore any other effect on earth; I'm only curious about how much and in what way gravity's affect on the light would distort what is seen by the eye. :)
0
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4answers
170 views

Multiverse Premier League [closed]

My parallel universe has the speed of light set at half that of Earth's (1.5*10^8 m/s). How would a Badminton player (P.V Bindu) from Dearth (my universe) fare against a player (P.V Sindhu) from ...
4
votes
3answers
134 views

Confusing predators with reflected or refracted sunlight

Imagine a large butterfly- or moth-like creature, with a wingspan of about one meter (it's moth-like, not actually related to Earth insects). It lives its entire life high in the open sky, never ...
5
votes
3answers
205 views

Flooding lights

I am designing a world with no sun, there is something similar to asteroids in a nebula, not having a sun means no light so I decided to make that "nebula dust" glow, this dust has the following ...
15
votes
3answers
961 views

How large of a telescope would one need in order to read someone's lips on a planet light years away?

If I wanted to image an Earth-like planet at a resolution where one could read the lips of a human speaking on the surface 1, 10, and 1000 light years away, how large would the telescope reflector ...
4
votes
8answers
2k views

How could there be a horizon on a flat earth?

I'm building a world that happens to be flat. Well, it has hills and mountains, but no curvature. However, I still want to limit the eyesight to a few kilometers even if there are no hills around. I ...
2
votes
3answers
221 views

What are some alternative methods of perception on 'dark' worlds?

For instance; life manages to develop on a planet orbiting a black hole. What are some methods that native life could use for perceiving the environment around them? (e.g. echolocation, sonar, gamma-...
3
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2answers
256 views

How to make a planet with differential gravity and constant daylight

I am hoping to create a planet with a greater rotational speed, making it oblong, thus causing differential gravitaion from the equator to the poles. I am hoping for the gravitarion to be lighter than ...
21
votes
5answers
3k views

What are the main problems with beaming light from the Sun to Saturn?

I recently finished reading the Kim Stanley Robinson novel 2312 - set, of course, in the year 2312. Part of the background to the political negotiations and ongoing terraforming in the outer Solar ...
10
votes
4answers
593 views

What could make a star violet?

Part of a series I'm starting since the recent What could make a star green? did quite well and others could use the information here in their worlds. There aren't any "violet" stars. When a star ...
90
votes
9answers
16k views

What could make a star green?

Stars are never green. When a star's spectra "peaks" in the green range, it also releases a significant number of waves of the adjacent colors - so "green" stars appear yellow or white. I want a ...
10
votes
3answers
678 views

Can we identify distinct “colors” beyond visible light?

Let's talk about the visible light "rainbow" In almost all depictions of the electromagnetic spectrum, visible light is shown as a rainbow, and adjacent parts of the spectrum are monotone in color - ...
2
votes
3answers
470 views

Adding mass to light (In laser weaponry) to convert it to kinetic energy

The fictional tech: Lets say I have a crystal, that when a light waves pass through it, imparts some of it's mass onto the light wave. - This is handwave and I'm cool with it. The crystal is ...
1
vote
2answers
327 views

Could a photonic engine actually work?

I have a very specific aesthetic in mind for my science-fantasy setting, technology is largely pneumatipunk supplemented with weired phonotic devices;for "reason" there are few electrical devices in ...
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3answers
127 views

scientific explanation for lack of a shadow [closed]

i am curious to know how to scientifically achieve the lack of a shadow for a person. what would have to happen technology wise for a person not to cast a shadow in direct sunlight. i have only ...
13
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4answers
6k views

Does mirror armour work against laser guns?

The next war will be fought with lasers beside computers, I'm wondering could a bullet proof vest coated with a highly reflective surface protects user from laser blast. The laser in question is ...
33
votes
8answers
6k views

A monochrome planet

I am asking if a planet with shades of gray only is scientifically possible in our universe. Basically everything on the surface of this planet would seem black and white to the human eye. Here are ...
6
votes
3answers
445 views

Effects of a Moon-sized Sun-Cannon on Earth

Inspired by this answer, If that Lunar-plant is used as a weapon (pointed toward specific cities/forest/seas/lakes), how much damage it could really do? Is that able to burn cities, or anything? I ...