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Why You Don't Want Invisibility

 You don't actually wantthe power of invisibility. What would you do if youcould turn invisible? Most of the responses I've heard to that question are less than heroic. Many of them come downto sneaking into places you shouldn't be or borrowingstuff without asking. Of course, you could use the power of invisibility for good. It is one of the fundamental hero powers. But thinking about the scientificreality of this ability, I don't think invisibilityis something you'd even want.

Like super strength and super speed, humans have fantasized about the power of invisibility for a long time. Suddenly disappearing is the subject of great novels like TheInvisible Man by H.G. Wells, the 1933 movie of the same name, and of course the masterpiece Hollow Man starring Kevin Bacon. Many of these stories have considered the consequences of turning invisible, but I think that sciencehas even more to say. So why wouldn't you wantthis classic superpower? First, what is invisibility? Well, whether the source of the power is magical or sciencey, to make something invisibleyou have to change the way that somethinginteracts with light. Everything that you cansee interacts with photons, elementary particles thatare the basic units of light and electromagnetic radiation.

Those photons of light areflying around the universe, and they enter our eyesand give our brains visual information based on theproperties of those photons, like frequency and phase. Now, everything that you can see, then, therefore is either emittinglight that reaches your eyes or is bouncing photons offof itself and to your eyes. So to make yourself invisible, then, you have to change these paths. However your powers worked, they would have to redirect photons so that they would either go around you or an object so that thosedidn't bounce off of you or an object and make it into your eyes, or the photons wouldhave to go through you, kind of like you were transparent. Or a third option isthat you could project what is behind you in frontof you and into people's eyes, kind of like how Predator'scamouflage might work and look.
Yeah, sorry, dude. Yeah, I don't know. Oh, heads up! How invisibility might actually work is the first real problem with this power. The easiest way to make yourself invisible would be to reroutephotons around yourself so that they didn't bounce off of you and into other people's eyes, but if you were doing this successfully, no photons would be entering your eyes to give your brain visual information, and you would be blind. You might be invisible toother people like Kevin Bacon, but they would be invisible to you too. Now, there is a solutionto this, but it is weird. The human eye is an incrediblysensitive photon detector. Experiments have shownthat we can register the impact of a single photonat the backs of our eyes. But that doesn't mean we seean image when that happens. Reportedly, it's like afeeling of seeing something without actually seeing it. So to see an image, weneed many, many photons hitting the backs of our eyes, especially considering thatupwards of 90% of photons that enter the front don't makeit to the back of our eyes.

They just bounce aroundall over the place. So to be both invisible and able to see, you would not only have toreroute photons around your body, you would have to route a lotof photons into your eyes. Which would illuminate them. Apparently this is whatMarvel's Invisible Woman does, but if you did this, your eyes would be visiblewhile your body was invisible, and that is weird. And gross. And doesn't really fit withour conception of invisibility and it would give you away pretty quickly. Get outta here, Kevin! Cut loose, man! Even if you weren't blind, even if you weren't just apair of disembodied eyes, another reason you wouldn't want the power of invisibility is that youwouldn't be truly invisible.

If you can make yourself invisible by rerouting photons around yourself, you'd probably want to dothis right above your skin or, better yet, at your skin,because if you were making . But if just your physicalform was invisible, you also wouldn't want anyobjects or the environment interacting with it togive away your shape. This would immediately limit your powers by making it impossibleto sneak through a world when it was either snowing or raining, and you wouldn't be able tostand in one spot for too long, because the dust and debristhat you would gather would also give away your shape. And in this conception of invisibility, you would have to be naked. So to be truly invisible, if you wanted to sneak around anywhere, you would have to be coldand naked and uncomfortable.

But at least you'd be invisible, right? Well, that depends onwhat is trying to see you. Every second, the average human radiates 100 joules worth of heat energy out into the universe in all directions. Anything with a temperature does this. And so you are always emittinglight, but infrared light. Now, I know we don'tthink of infrared light like we do visible light, butconsider the term red hot. When something is red hot, it is radiating enough heat energy that its wavelengths of infrared light are being pushed up into red light.

Visible light. It's all on the same spectrum. And so even if you were invisible to people looking foryou with visible light, anyone that was lookingfor your heat signature could see you just as easily as if you were not invisible at all. Heads up! Ha ha, missed me by six degrees. Kevin! No! So while classic invisibilitywould hide your visible light, anyone with something as simple as a thermal cameracould pick you up easily. This wasn't a problem back in 1933, when The Invisible Man movie came out, but today we have thetechnology which would make it almost impossible to sneakundetected through most of the places that you wouldwant to be undetected in. Anyone with a motion or thermal camera, the most common securitymeasure in homes and banks, could pick you up easily. Which would be good, becauseI know what you would do if you were invisible,you bunch of creepos.

I know. You don't have to say it. We all know. Even if you weren't blind, even if you didn't have to be naked, even if you were somehowcompletely undetectable, you still wouldn't want invisibility, because of your own brain. I want you to try something with me, okay? Close your eyes, it'll be fine. Close your eyes, andextend one of your arms. Now extend the pointer finger on that arm, and now bring the tip of your finger to touch the tip of your nose. Okay, now open your eyes. Easy, right? Most people can get within 20 millimeters of their nose first try, no problem. But how can we do this? How are we able to position something accurately in space that we cannot see?

Well, it is thanks to a sense that we have but you may not have heardof called proprioception. It is our body's movement sense. Without proprioception, wewouldn't be able to drive without looking where ourfeet are on the pedals. We wouldn't be able to typewithout looking at our fingers. And we wouldn't even be able to walk without watching our feet on the ground. We wouldn't be able to dance either. I'm sorry. Proprioception relies on information that your body is constantly generating.

Your muscles and your ligaments tell your brain how yourlimbs are positioned in space relative to the rest of your body. All of this informationcombines in the brain with visual informationto give you an idea of where you are and how you are moving. Or not. Incredibly smart boy andneuroscientist Oliver Sacks once told a story of just howimportant proprioception is to our everyday livesin his fantastic book, The Man Who Mistook His Wife for a Hat, which I highly recommend. In it, he describes a patient, Christina, who actually lost her movement sense, thanks to a viral infection in her spine.

Now, Christina made a partial recovery, but only because shelearned to rely entirely on visual information andnot her movement sense. For example, she was able tograsp a fork again to eat, but when she did so, shehad to grab the fork so hard that it hurt her handsand they turned white. As Oliver Sacks put it, Christina was able tohave a possible life, just not a normal one. The sense of your own body, combined with visual information, is critical to normal functioning. So now imagine what itwould really be like to be classically invisible. That is invisible butunable to see your own body. It would be the other versionof what happened to Christina. Think of how hard it would be to walk down a flight of stairs if youcouldn't see your own feet. You could only feel where they were. Imagine how hard it would be to manipulate and grasp objects with zero visual input. There we go. It's not impossible, butit's not very super either. Being invisible wouldbe an incredible hassle. Just walking down thestreet would be so hard.


No, people wouldn't be ableto see your naked, weird body, but you wouldn't be able to see where your body was in space either. And so you'd be stumbling down the street, bumping into other people and obstacles, cold and confused all the while. It would be miserable. So why wouldn't you want the classic superpower of invisibility? Well, it wouldn't make youfeel very superpowered at all. Quite the contrary. You would either be blind ora weird pair of floating eyes. You would be cold and naked. You would be completely visible to anyone with widely available thermal tech. And without the visualinformation that your brain needs, along with your movement sense to make movement through lifepossible and bearable, doing anything while invisible would be, at best, frustrating and,at worst, impossible. If you really could go out of sight, it would drive you out of your mind. Because science. Ow! Dang it, Kevin, you kickedoff your Sunday shoes, and I tripped over them! Basically, to make invisibility work, you have to do a lot of weird stuff.

You could route photons into your eyes and then out of your eyes after they bounced off of your eyes, or you could make yourselfcompletely disconnected from the electromagnetic spectrum, but then you'd fall through the earth and stuff. So you'd have to jumpthrough a lot of hoops. Regardless, classicinvisibility, I don't think, is as cool, or nearly as cool, if you think about it scientifically. See? Same problem.

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Terms and conditions apply, and offers are subjectto change without notice. Visit LifeStream.com forimportant information about limits on LightStreamloans and same-day funding. Thank you so much for watching, David.If you're on Facebook, like,and if you are on YouTube, make sure to like and hitthat notification bell, fam, because we get up to a lot of weird, fun, geeky stuff on this channel.

If you want more ofme, go to Project Alpha at ProjectAlpha.com,where if you sign up now, you can get this show two daysearlier than everyone else, and you can get a geeky debate show that I do with my friend DanCasey called Natural Selection. If you want to follow me and Because Science onsocial media, do so here. Bye. 

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