Is it theoretically possible to become invisible and if so how?
In: Physics
Well for one it depends on your definition of “invisible”. If you mean “not visible to the naked eye”, sure, just turn the lights off.
If you mean invisible to the naked eye in daylight you could hide somewhere…
Now these are obviously trivial and probably not what you’ve meant but I just want to make clear that “invisible” is relative, it just means “unable to be seen”.
Now if you want to be invisible while using neither of the trivial techniques you could theoretically have a suit that captures light from one side and projects it into the eyes of who ever you want to be invisible to. This would not be very scalable though as projectors would create potential “blind spots” (like the blind spots in our eyes where the eye doesn’t capture light).
You could also try to bend light around your body by using some medium. You basically have to find a way for light from “behind you” to reach the eyes of the observer while no light that hit you does.
But depending on the medium you use you might be invisible within a certain spectrum but visible in a different spectrum, because the refractive index for example depends on the wavelength of light.
So first you have to define your “invisible” and then find a technique that achieves that goal. Being invisible to humans without technology is very different to being invisible to humans with technology, or being invisible to radar, sonar and so on.
In the end, theoretically there are multiple ways to become invisible and I’ve actually seen some tests of the projector method years ago that worked quite nicely. I don’t know whether there are more techniques.
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