Is it possible to create a bulb which can produce darkness instead of light?
No, but let’s imagine a fictional question: What’d happen if you have a bulb producing darkness?
There are other questions answering the real question so let’s just have some fun with this one.
So, now we have a bulb producing darkness!
Let’s list some “realistic” facts about out bulb:
Darkness is just the absence of light.
Humans only perceive certain wavelengths.
Humans perceive light if the photon hits the cornea.
So this bulb accomplish at least one of the following tasks:
Absorb the light.
Change the wavelengths of the visible spectrum.
Change the direction of the light that’s supposed to hit the cornea.
So, lets begin with the first idea:
The bulb absorbs the light!
Fantastic! We just created a black hole!, Now for the good sake of humanity and to have a bulb that at least works more than 1 second let’s just imagine one of the multiple properties of the black hole: ABSORBS LIGHT and modify the trajectory of the light
To all the light there only will be two outcomes: it’ll be absorbed by the bulb or it will be deviated.
Now, let’s imagine you are in Central Station, NY, and you turn the “darkness bulb” on in the middle, what’d happen?
You won't see nothing if you focus in the bulb and all the surrounding light that won’t be absorbed by the bulb? Well.. I think everyone in Central Station will feel like they are drugged (you’ll probably see like this).
The black dot will be where the bulb is and I think you’ll see like this if you stare at the bulb. All the light, including the light behind you, may return to your eyes due to the bulb.
Now there are good and evil purposes for this bulb, let’s just keep the more interesting ones:
If you rob a bank and turn the bulb on just above your head, no cameras will perceive your face. If the police try to shoot at you they’ll probably miss cause they won’t see most of you or they’ll miscalculate your exact position.
If you are lazy and want to look behind you just turn the bulb on and the light coming will “magically” appear in your eyes.
Now, the bulb changes the wavelengths of the visible spectrum.
There are two options here: either the bulb produces a “wave” that transforms the wavelengths or it’s kind of a glass that modifies only the light that crosses the bulb.
If it’s the first one then you really have a “darkness bulb” because it causes.. darkness, the second one would be more like a camouflage or invisibility. Let’s keep just the first one:
We have a darkness flashlight that works just modifying the wavelength into infrared (for example), we would point at any object and suddenly it “disappears”, no longer visible!
So, you’re in the highway, you point directly to the next car, what would you see? just black as a circle from the black hole flashlight? well.. not exactly… We have to remember that the light that you see is the reflection on light into objects so you are modifying the reflection of the light into an object making it not visible… just like air, so it’s an invisible flashlight? yeap. In the daylight there’s that much light that your flashlight will be an invisible flashlight but in the night it’ll be a darkness flashlight, It depends on the amount of light where you are, if you’re in a open space it will just disappear objects but in close spaces it’ll be darkness.
Now, let’s imagine the distance your flashlight covers would be a mile, then you point it directly to the sun.. well as in the night all the objects that still get in touch with light will reflect their light and you’ll be still seeing objects, obviously you’d experience a darker day depending on the power of the bulb. In order to “provoke” total darkness you should me able to cover the hole sun and stars light.
The “thing” that change the direction of the light that’s supposed to hit the cornea.
This “thing”’s only purpose is to point directly to the eyes of the humans and change the direction of the light of modify the wavelength (as the first and second bulbs does).
Either the “black hole” bulb and the “wavelength” bulb are very unique. With all the light in the daylight just imagine you could use the bulb only to “illuminate” you.. then you’re invisible but with the “black hole” flashlight probably you could manipulate become the most famous scientist.
If I have to choose I’ll keep the wavelength flashlight, being invisible has many benefits, just imagine how many pranks you could do!