# Anatomically correct Kryptonian, part 1

Part of the Anatomically Correct series of questions.

Due to the nature of Superman having so many different powers, I wanted to focus specifically on one aspect of his character: the ability to be powered by differently colored suns.

For this question, I am looking for a creature that becomes stronger (or weaker) when in the presence of suns of different colors. This raises an important question: Is there a difference between receiving red light from a red star, and receiving red light from anywhere else? My answer is this: If it is possible, I'd like the creature to respond only to sunlight. If this is not possible however, the creature may be powered by all forms of light that have the correct wavelengths, regardless of its origin. (for example, there are grow lights that simulate the sun's energy)

The following is how the creature should react to the various wavelengths:

• Red sunlight: No change or increase in strength; this is the default state.
• Orange sunlight: Creature has a slight increase in strength
• Yellow sunlight: Creature becomes much stronger.
• Blue sunlight: Creature becomes even stronger than from yellow sunlight.

The argument from the comics is that more energy is received from suns towards the blue and yellow range than suns near the red range of the spectrum.

I did some number crunching using the equation for photon energy, $$E = \frac{hc}{λ}$$ and found that the energy of photons with a wavelength between 450-500 (blue range) have about 1.44 times more energy than photons with a wavelength between 620-750 (red range).

# How might a creature evolve to receive more energy from higher-energy wavelengths of light?

• Creature must not need higher-energy light to survive. Kryptonians, for example have lived most of their lives under a red sun, exhibiting virtually no superpowers at all.
• Creature must get much stronger under yellow light. For the purposes of this question, let's assume that "much stronger" means their muscles are more than 2x stronger than usual; they can carry double the normal maximum weight.

Optional conditions. Addressing these will give you more points towards best answer:

• Creature gets even stronger under blue light. For blue light, let's say that it makes them 2x stronger than what yellow light does.
• Creature increases strength almost instantly. Rather than taking a long time under the sun to begin exhibiting increased strength, the effect happens almost immediately.
• Creature shows signs for a while even after exposure ends. For Superman, he "stores the sun's energy" in his cells, which enables him to have superpowers for several hours after he is no longer in the sun. This allows him to use his powers at any point during the nighttime in addition to the daytime (during which he is "recharged").
• Creature doesn't need light at all to survive. I understand this might be a stretch, since a creature that has evolved to gain strength from light obviously would have done this for a reason.

For this question, ignore any of Superman's other superpowers.

Worldbuilding context: I was working on a plant-animal hybrid for my world that gains strength based on light frequency, and suddenly I thought "Hey, this kind of sounds like Superman."

• Comments are not for extended discussion; this conversation has been moved to chat. Commented Nov 28, 2019 at 18:40

If we want it to be realistic, there is no way. This is result of few factors:

The solar radiation on the earth in the upper atmosphere (before it is reduced by atmospheric effects and clouds) is 1300 W/m^2. Human body surface is 1.9 m^2, and at least 1/2 of it will be facing away from the sun. Then following that the shape of your body will reduce the effectivity even more. In the end, you end up at some 1000 W in extremely idealized condition. And that's assuming 100% successful energy capture, which is laughable.

That's not enough for superhuman feats. Human usually runs on around 100 W, but that's for rest. When doing extreme feats, their energy output can go up to 1200 W. Even assuming 100% energy conversion rate, aditional 1000 W under ideal conditions is something, but it's kind of, well, meh. Nowhere near close enough for Clark Kent level performance.

So, in the real world, we sadly have to give up. But if we alter the world a little bit, and allow a bit of handwaveium, there's an interesting solution that I believe deserves attention:

Let's be honest, Superman as we know him shouldn't suddenly get weak because he went underground, or there were few cloudy days. You also don't want him affected by lamps. So, we should go in a different direction. Neutrinos. Your superman doesn't absorb energy from sunlight. He absorbs energy from neutrinos.

Right now, there are 100 trillion neutrinos passing through you each second. Most of those are produced in our very own sun. On average they have around 400 keV energy (that's what my preliminary check says, and I'll correct myself after I get feedback on a physics forum I'm member of).

Well, the problem is that total of that is just about 2.3% of solar output, that is around 30 W[corrected after gathering more information]. That's two orders of magnitude less than you could get from sunlight. But unlike with sunlight, with neutrinos, changing rules of the world to fit more neutrinos in is far simpler.

Neutrinos don't really react with normal matter, so even if in Superman's universe, energy of sunforged neutrinos is 100-1000 times higher, the effect on the planet itself will be basically none. You can't do that with sunlight, even 30-50% more sunlight is enough to turn Earth into second Venus.

Effect it would have on the universe itself is different, but seriously, any minor manipulation with universe's laws has headache inducing consequences, and it's probably possible to balance it out with some other changes.

• It allows Superman to tap into source of energy produced by star, that neither humans nor animals nor plants can access.

• It doesn't make Superman go weak when he's underground, as the neutrinos still reach him unobstructed, when he's under the roof, daytime or nighttime, etc...

• It makes Superman's power greater near more active stars (where more neutrinos are produced).

• It actually allows Clark Kent to obtain enough energy to be a Superman and overall fits the requirements for him to be a Superman.

Problems are:

• It requires different universe, as the energy produced in form of neutrinos by stars here is not enough around yellow star.

• It still doesn't solve how Superman captures the neutrino energy and converts the energy into physical strength and toughness(which, honestly, is only possible in realm of handwavium anyway, no matter what energy source we give him. And honestly, Krypton already has Kryptonite).

Clearly you're talking about a photosynthetic organism, albeit one with very precise responses to different wavelengths.

My suggestion would be a creature that evolved on a planet orbiting a ternary star system, where the wavelength of sunlight changes dramatically in a cycle with a period of months of years, and which has evolved such that this cycle regulates its breeding cycle. Multiple photosynthetic pigments in the cells absorb energy over a range of wavelengths, but the changes in "strength" are actually hormone-driven rather than directly coupled to the photon energy.

During the 'winter' period where the red dwarf star is dominant, a hibernation-like behaviour occurs: biorhythms slow down, active movement is minimised, strong urge to sleep. The need to store energy through this period explains why Superman is able to store energy through the night and 'recharge' during the day.

The emergence of the yellow star from eclipse behind the red giant marks the beginning of the 'spring' phase of the cycle, where the creature becomes more active and starts to actively feed and prepare for breeding. This transition is very sudden, and there is an evolutionary pressure to react quickly to it - perhaps the creature hibernates in riverbeds which will be very quickly flooded by meltwater, or there is a need to immediately shelter from predators who only hunt in the yellow light (the reverse, needing to hunt prey which only emerge in red light, doesn't really make sense for the creature to still get its energy from sunlight).

Finally, the brief emergence of the blue star heralds the mating season, where the creatures must demonstrate great strength and energy in order to compete in mating rituals. Stored energy is used to supplement the blue light for this short phase, which tails off when the blue star returns to occlusion and females of the species return to hibernation; males may retain an energetic state for a short time to 'mop up' any remaining females, before hibernating again themselves.

The "only responds to sunlight" condition is tricky. It's not really possible for the creature's photosynthetic pigments to only respond to photons of the correct wavelength which have been produced directly by stars. However, stellar spectra are not perfect black-bodies, they have absorption lines where particular frequencies are 'knocked out' by absorption by gases either in the star or in the atmosphere of the planet. An evolutionary vestige may mean that light of a particular wavelength (not present in the spectrum of their homeworld) causes a destructive reaction in their cells, which could range from sunburn to toxic shock; the effect of that would be that 'full spectrum' blackbody radiation such as from a fire or incandescent light source would be toxic to them. You could calibrate this such that 'domestic' lights are not powerful enough to either recharge them nor poison them, but sources powerful enough to draw charge from must be properly filtered in order not to cause pain or damage.

It's a photosynthetic organism with very efficient pigments. They have to be because the organism is a bipedal animal without leaves, not even elephant's ears. The efficiency comes at a price, and the price is being tuned to narrow spectral ranges.

When their skin is under the correct illumination it will convert carbon, water and light into glicose, the carbon comes both from the air and from the organism itself, when in photosynthesis mode the organism exhales less CO2. The extra oxygen the skin is producing is captured by the hemoglobyns, so under the correct frequency the creature has access to much more energy: it produces some of it's own oxygen, rids itself of CO2 and get sugars in the deal. That translate in more endurance compared to earthlings. The extra glicose, not being used, is first stored in the muscles, like creatine. If it isnt used for a long time it is used to fuel muscle building and healing instead of fat building.

The creature eats like a horse as they say: it need a lot of carbon and mineral traces to keep the carbon flowing to the skin and the photosyntesis running.

It will also needs to be heat tolerant: it's body temperature will rise a lot under the strong sunlight, so the cells will need enzymes like the ones in the extremophiles. Or energy sinks like muscle building, a very fast and powerful brain.

About the planet, I would go with @Stephen sugestion. Also, ALL "animals" in this world are like this creature, these adaptations appeared very early in the history of the Metazoa there.

Another consequence: the creature was not made to stay indefinitely under yellow or blue suns. It's lifecycle assumes some rest from the overcharged photosynthesis during the red phase. On earth it will keep building muscle and bone tissue, getting stronger and stronger until it reaches it's physical limits and will suffer a lot if deprived from the solar energy, it won't have the means to keep it's beefed-up body running for long.

Conclusion: the creature gets stronger and stronger under certain, specific light frequencies, eats like a horse, has a very accelerated body and mind, its the tough figher you ask.