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I was wondering about the practicality of some superpowers. If someone had the ability to fire lasers out of his/her eyes, would the advantages of this ability be sufficient to overrides the risks? The problems that immediately come to mind are that:

  • such an ability would likely blind the user for at least a few seconds (bad thing in a fight)
  • no matter how you focus the heat, it just doesn't seem like a good idea to fire something like that near your brain. (Really bad thing always)

On the other hand, firing a perfect shot — laser goes out and follows the direction of your sight — at the speed of light will always be a good thing.


I wasn't clear about this, but firing the lasers will probably not kill or maim you. I'm just naturally worried about the word "probably". It means I might die.

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    $\begingroup$ You hit a lot of the points I would consider. You might also think about energy requirements. For example, how many calories do you burn shooting a laser blast? That's always something that tends to break my immersion concerning superpowers. $\endgroup$ – MozerShmozer Jul 19 '17 at 17:55
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    $\begingroup$ This seems relevant $\endgroup$ – Draco18s Jul 19 '17 at 20:35
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    $\begingroup$ @SJuan76 I AM SUPERMAN!!!!!! Seriously, I'm not so worried about the costs of activating it so much as the side effects of the power. $\endgroup$ – Josh Taub Jul 19 '17 at 23:05
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    $\begingroup$ This seems relevant: clayyount.com/hamlets-danish-comic/2014/4/7/any-power $\endgroup$ – n_b Jul 20 '17 at 3:12
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    $\begingroup$ David Brin's first novel, Sundiver, included an alien with laser eyes, and how they work becomes an important plot point. en.wikipedia.org/wiki/Sundiver $\endgroup$ – bgvaughan Jul 20 '17 at 16:04

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I love worldbuilding questions which touch biology!

I would argue that it's not so bad as some other people here present. The main question is, where does this power come from? Evolution? Magic? Technology?

Depending on the answer to this question, some the problems listed above could be easily or very easily solved.

  1. Saccades and blinking are controlled by nervous system and are thus easiest to solve - in fact, nature and engineering has already solved a number of similar problems.

    ex 1. WWI fighter planes had initially a huge problem with firing on one another because the machine gun was mounted behind the propeller, so when the gun fired, the bullets often hit the propeller fans. This was solved quicklly by a simple mechanism which synchronised the firing and the propeller. The same could apply here, with a switch blocking blinking and saccade reflexes during the beam firing.

    ex. 2. Swallowing vs breathing - You don't have to control Your breathing while drinking a tea, dont You? The nervous system is wired to do that for You.

The only question is, how was the nervous system taught to block the reflexes during laser fire. Evolution could do that for You easily, otherwise it was directly magical or technological manipulation (hard stuff).

  1. Burning the lenses - well, we have two options here. First, who said that the laser has to originate from the eyeballs themselves? Maybe it's origin is right in front of the eyeball? Second, there are a lot of transparent materials which have no problem with passing the laser through - especially if the laser is really, really monochromatic. Again evolution would have no problem doing that, since it already produced lenses transparent in the visible spectrum (and the wider the spectrum, it is probably harder to adapt to it). Magic could probably do the same, the technological solution would probably be the hardest here.

  2. Scattering - practice, practice, practice. Again, evolution could help a lot by doing some additional hardwiring in Your brain, and so could technology and magic. Frogs are super precise with shooting their tongues, and so is Vash the Stampede in Trigun (well, he is precise with guns, not tongue).

  3. Power supply - this depends on the physics of Your world, but since we are discussing laser-shooting-eyes, I assume that it's at least a bit different from ours.

I also wanted to point out that whatever Cyclops in X-Men is shooting, it's not laser, it carries way too much kinetic energy.

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I'm not an optometrist or ophthalmologist, but it seems like if you fire a laser through the lenses of your eye, and that laser has sufficient energy to burn a target at a distance, then it stands to reason that this would cause you more than a few problems.

Several specific issues come to mind:

  1. It would raise the temperature of your vitreous bodies so high and so fast that your eyes would effectively flash-boil and explode under pressure. In fact, until the vitreous body boils off, this gel would diffuse your laser to the point that it couldn't be focused on an enemy.
  2. If that didn't happen, then the lasers would melt your eyes' lenses.
  3. For the duration of your laser-attack, you cannot even glance in any other direction. No instinctive glance at movement in your periphery, or you just torched a hundred meters of ground for no reason.
  4. You must make all of your attacks a staring contest. Don't blink. Don't want to burn your eyelids off.

I would suggest that you instead fire your lasers from your nostrils. Burning a few nose hairs is far less damaging in the long run.

Or maybe prehensile mustache lasers?

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    $\begingroup$ If you use the nostrils don't accidentally fire into your pubic area... $\endgroup$ – L.Dutch - Reinstate Monica Jul 19 '17 at 18:02
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    $\begingroup$ @L.Dutch and whatever you do, DON'T SNEEZE! $\endgroup$ – CaM Jul 19 '17 at 18:26
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    $\begingroup$ Even if you could overcome the issues with the vitreous humor boiling inside your eyeball, you'd still give a whole new meaning to the phrase "don't blink!" $\endgroup$ – Cort Ammon Jul 19 '17 at 18:31
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    $\begingroup$ You also have a related problem of heat dissipation. The most efficient lasers are about 70% efficient, but the most efficient quantum cascade laser (the kind that is small as a grain of rice) is 28% announced in 2016. So your eyeballs are going to explode as they flash into steam. Nothing is going to prevent your brain from being destroyed either. Sadly, nostril lasers will also have a fatal result. $\endgroup$ – Gary Walker Jul 19 '17 at 19:29
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    $\begingroup$ Most superheroes with laser eyes also conveniently come with some form of increased durability, rendering the effects on conventional eyes moot. As the most famous example, Superman of course has super-eyes. Because yellow sunlight. This makes his eyes resistant to his own heat vision because of reasons. It's all very logical when you don't think about it. $\endgroup$ – Jeroen Mostert Jul 19 '17 at 21:55
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Laser eyes have always been Rule of Cool. The power constraints (a laser that does substantial damage in a short time) mean that there's no current energy source that would be man-portable (let alone contained within the eye) and fit the bill. As mentioned in other answers, the biological nature of the eye (the optical purity of its lenses and vitreous humours) also mean that emitting such a beam from within the eye will be incredibly and permanently damaging. And the constant movement of the eye (edited out of our vision by our brain) makes a mockery of "precise aim".

So let us ignore the biological eye, and go with the bionic eye. This avoids the presence of any imperfect biological elements incapable of withstanding the beam, and a camera feeding data to the optical nerve can artificially simulate the minor movements of a natural eye, while remaining rock-steady on the object of focus. The remaining problems are bloom, power supply, space constraints, and cooling. Assuming that you want to do laser cannon-like damage (not just blinding a target like a laser strike), you're talking a laser in the hundred-kilowatt range, easily.

Northrop-Grumman's Firestrike laser is in that range... and it weighs about a ton and a half and requires about a megawatt of power to operate. Definitely plausible on a battleship, less plausible inside someone's head. In addition, a major concern of battlefield lasers is bloom - both for beam diffusion and (important for the person from whose face the laser is emerging) heat blowback near the weapon. If the hypothetically laser-eyed individual is shooting his lasers in a vacuum, that is no longer a problem - but they're encountering different problems. So, even with artificial eyes, the technical challenges are substantial.

So, at the moment, even replacing the fallible human eye with something more robust, so many technical and physical challenges would need to be overcome that any application of it may as well be called "magic" and left at that - as with Cyclops and most of the other X-Men. In that case, magic can provide the power, magic can determine where the beam is supposed to go, and magic can protect the wielder against the adverse effects of their own beam.

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    $\begingroup$ ...never mind the adverse effects of the power itself. Dissipating a megawatt is no small feat. Find yourself a 100W lightbulb that's been on for a while and touch it, and you'll know what I mean. Now scale that up by a factor 10,000. $\endgroup$ – a CVn Jul 19 '17 at 18:33
  • $\begingroup$ Welcome to WorldBuilding! If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$ – Sec SE - clear Monica's name Jul 19 '17 at 18:55
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    $\begingroup$ Those “minor movements of a natural eye” are called saccades and serve a few purposes. Depending on how those non-biological eyes function, they may not require such saccadic movements. $\endgroup$ – can-ned_food Jul 20 '17 at 16:06
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    $\begingroup$ Also, remember that when you say replacing the eye with something more robust, you are really trading a receiver for an emitter. $\endgroup$ – can-ned_food Jul 20 '17 at 16:07
  • $\begingroup$ The frequency of the beam matters to whether or not the humora/lens will absorb much of the energy or basically ignore it. It's been decades since I looked at that sort of data for the human eye, (and I wasn't thinking about slipping lasers through at the time) so I can't say for certain there is a good band to slip through, but it seems likely that there is. $\endgroup$ – The Nate Jul 20 '17 at 18:14
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Ignoring all the biological factors of firing lasers from your eyes, actually aiming at distance (more than a few yards) will be complicated greatly by the eyes natural nystagmus (back and forth motion of our eyes that the brain edits out) which would cause a laser beam to wave around. Though I suppose you could just dampen the effect while emitting the beam. There is also the converging nature of the beams, so they would cross at the focal point, not just shoot out in parallel beams.

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  • $\begingroup$ Though, crossing the beams in this case could actually be a good thing, if you make the beams some magic wavelength that has an additive effect only when they combine $\endgroup$ – Wayne Werner Jul 19 '17 at 19:37
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Prepare for a lot of collateral damage

While it might seem like it's easy to aim your eyes, it's actually very difficult to keep them perfectly still. Only a small amount of the retina gets a clear and perfectly focused image, so your eyes are constantly flicking around to take in the details of a scene. These flicks are called "saccades", French for "jerks".

Even when you're staring at something, your eye position isn't continuously controlled by the brain. Rather, your brain notices when the eye has started to drift off target, and jerks it back into correct position.

This process isn't consciously controlled, or even noticed, because your brain processes them out to give a steady and continuous image. But if you're firing a laser at any significant range, a flicker of just a few degrees would be a real problem.

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Definitely unpractical.

As others have pointed out, heat dissipation would make your eyes and brain to explode almost instantly.

Moreover, your vitreous bodies would turn into plasma right away. The interesting thing is that from that moment, it would reflect most of the beam, throwing more energy back to your brain that what comes out of your 'eye'. The current works related to handheld laser guns take it into account as hitting flesh with a laser would raise its outer layers to plasma, which would subsequently protect the inner layers from the still hitting beam. The solution they propose is to altern periodically between the regular power of the beam and a significantly more energetic beam in order to blow that plasma layer out of the way.

Interestingly, these same works balance the pro of throwing cheaper energy than balistic weapons with the con of the fragility of the lenses. Indeed, the lenses themselves would be progressively damaged by the beam, lessening their optical purity. A decrease of purity would decrease the amount of energy that's sent toward the target. The difference would be absorbed by the lense itself, damaging them even quicker.

The nature of laser itself - light - brings the advantage of range and its proverbial speed, but any alteration of the optical purity of the medium through which it travals would reduce drastically the beam's energy losses per meter. Dust, rain, humidity, you name it.

And even if you can somehow overcome these cons or make it work in spite of them, you'll be the proud living casing of a weapon that can be deflected by wearing light reflecting clothing.

Although they are among the optimum cool, laser beams become pretty quickly dull once you begin to treat them realistically. In your example, I don't see how you can present your character with laser eyes without having that character have some man-made organs, likely its eyes, its whole face and maybe its brains. Or if it's a magical power rather than a mutation or a technological enhancement, if you're willing to take that road.

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  • $\begingroup$ Welcome to WorldBuilding ksjohn! If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$ – Sec SE - clear Monica's name Jul 20 '17 at 10:58
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One of the reasons people don't have super-powerful lasers at home is the risk of retroreflection: the laser hits something reflective and bounces back and harms you.

So is laser-eyes practical? Probably not for combat.

It can be defeated with 3M's retroreflective material which is cheap and readily available. That's a pretty significant Achilles Heel, comparatively; Kryptonite is difficult to obtain, building a prison out of plastic is enormously difficult.

And it makes

firing the lasers will probably not kill or maim you

into

firing the lasers will probably kill or maim you

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On the other hand, firing a perfect shot — laser goes out and follows the direction of your sight — at the speed of light will always be a good thing.

I'm not sure the factor of instant and automatic aiming wherever your eyes are looking and focused is an advantage. In addition to the micro adjustments and involuntary spasms of the normal eye movement, don't forget the event of momentary distraction...

Team mate: "Hey, Jack!"
LazerGuy: "Huh...?"
Team mate: [frazaaaap]
LazerGuy: "oops"

Or a bystander runs across the field of view behind the target. Just takes a fraction of a moment to fry the bystander.

And what about a person with laser vision that has a lazy eye? THAT can't be good...

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I should probably update when I get home to get the direct citation, but on top of the other issues, Physics of Superheroes points out that in Cyclops' case, he apparently actually has 2 superpowers: laser eyes (or whatever you want to call it) PLUS a superstrong neck/general skeleton to handle the for every force there's an equal and opposite force factor.

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Practical is such a misunderstood word. It often is taken to mean possible. But really it means efficient. Your question is asking not are laser eyes possible but are they useful.

It sounds like you are asking both questions though. Is it possible?

Superman is alien. By definition not human. So comparisons to the human eye are a bit of a waste of time in his case. Superman is stronger faster and nearly indestructible. Sounds to me like any damage he could do to himself is nullified by his indestructibility. He flies into the sun for a recharge. A little laser wont bother him.

As for where he gets his power. He flies into the sun for energy. He is solar powered. And the sun easily has the power to fuel laser eyes.

The real question is it useful. A built in high powered perfectly accurate weapon? Yes it is useful.

As for humans with laser eyes see the other answers here. But I thought it was worth pointing out the obvious exception to most of them.

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