Is it theoretically possible to become invisible and if so how?

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Is it theoretically possible to become invisible and if so how?

In: Physics

5 Answers

Anonymous 0 Comments

We’ve actually achieved this with special metamaterials in laboratory settings. Essentially, light is bent around the object so you see what’s behind it, kind of similar to the gravitational lensing effect around black holes. As you can imagine, militaries are very excited about this technology, but as far as I’m aware, we’re likely at least a decade away from having this applicable on an everyday object outside of a lab.

Anonymous 0 Comments

My comment might get removed for not providing a decent enough answer, but I recently watch The Invisible Man which….

SPOILER ALERT

… hinted at a suit that had thousands of cameras attached so that each camera could shoot and then display what it was seeing in its environment – rendering the wearer invisible. I suppose it’s just he same as chameleons and octopuses but with more technology involved.

Anonymous 0 Comments

Theoretically yes, piratically no, at least not for common understanding of the word.

You might try to argue semantics and try to convince people that stuff like darkness, fog, smoke or even a blanket thrown over somebodies head count as invisibility because they prevent you from being seen, but for most people invisibility has a very fixed meaning:

It means that people will look at you and instead of seeing you they will see something that looks like what is behind you as if you weren’t there.

Most of the ‘stealth’ stuff we have for planes and boats, does not satisfy that requirement. These stealth vehicles simply are built to reflect radar as little as possible.

Camouflage as used by the military might be closer to it, but it mostly relies on dressing people in something that sort of looks like the background and our eyes not being very good at telling the difference.

Active camouflage that changes coloration and texture pattern to matches the background would be even closer, but we aren’t there yet. Octopuses can do that (and also change their shape), but technology can’t reproduce it yet and even if we could it wouldn’t be true invisibility.

For true invisibility we would need to reproduce the background exactly, which gets hard when people look at you from more than one direction.

There are some people who think that new materials may help with that but so far it is al science fiction.

One big problem with depictions of invisibility in fiction is that if all light passes either through you or around you somehow magically, you would be effectively blind. (If not blind you would appear as a pair of eyes floating in the air.)

Another problem often ignore in fiction is how far into the electromagnetic spectrum invisibility should extend. You could just cover the frequencies that human can actually see, but that would leave you visible to all sorts of animals and detection equipment.

Even worse humans don’t just reflect incoming light they also give off some infra-red light of their own. There is nothing we can do to stop that. Warm stuff giving of light is a fundamental part of how the world works. Cooling a human down to prevent them from giving of infra-red light, would actually make them more visible (and uncomfortably cold). Any attempt to magically capture all outgoing infra-red light inside an invisibility field would sooner or later cook the human if left on for too long.

This is also why any notion of ‘stealth’ in space is nonsense. You can’t hide the heat you give off.

So in conclusion, we may invent all sorts of technology to hide ourselves better an become less easily visible, but true invisibility would require magic or technology sufficiently advance to be indistinguishable from it and also leave you blind, and hot and still easily detectable by anyone really looking/listening/smelling after you.

Anonymous 0 Comments

Not really. Becoming invisible is largely something you see in science fiction and fantasy rather than actual life.

Invisibility requires either bending light around you or making yourself completely transparent. There is no feasible way to do either thing. It’s a fun idea to speculate on (like time travel or invincibility) but has not bearing in actual science.

Anonymous 0 Comments

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.