I am writing a story with an immortal race of aliens with psychic powers. Their minds are separate from their bodies and located in a pocket dimension inaccessible to ordinary matter. Their bodies are psychicly animated stone or metal.

Notable points:

  • They can die temporarily (ie: get disconnected from their body) by being crushed or vapourised. They can re-animate their original body or construct a new body from material in a 100m radius of where they died. They can also die permanently if they run out of energy and have no way of getting more.

  • They can only control one body at a time. Only one immortal can control one body at a time. Control over their bodies relies on the (cross sectional) area of each limb, stick-like limbs are not as strong as tree trunk-like limbs.

  • Older immortals are more powerful than young ones. Old immortals generally control larger bodies and have more powerful psychic powers. Immortals are motivated to have large bodies because this gives them increased awareness of the world around them. They can only communicate and interact with each other through the physical world, mind-to-mind communication is impossible. Their bodies act as an 'anchor' and allow them to interact with the physical world so the loss of a body entails complete loss of contact with everyone.

  • They reproduce slowly (compared to humans) with a new generation every 250-500 Earth years. Reproduction is like mitosis, the mind splits a little bit off. This mind fragment will have to construct a new body for itself.

  • Cancer or other diseases are not an issue but they need to absorb energy or they will become less powerful and later completely impotent. Energy can be absorbed as Heat. They take advantage of the energy gradient between their home dimension and their body in order to absorb energy. Using their psychic powers drains energy and they can absorbe energy through their stone/metal bodies. Larger bodies require more energy (proportional to the weight that needs to be moved) but can also absorb more energy (absorbsion is proportional to the surface area of the body).

  • The immortal aliens prefer hot rocky planets, like Venus and Io (Jupiter's Moon) and are currently about Kardashev I or a little below. They can only use solid rocks or metal for their bodies and have access to most surface minerals. They are not a highly technological species, they prefer to use their psychic powers. They only need energy (solar prefered) and a suitable material for their bodies. Material for shelter is optional. They can only anchor to solid objects.

  • Their psychic powers include Telekinesis, Levitaion and Pyrokinesis. Moving an object telekinetically requires the same amount of energy as moving it by normal means. The same with Levitation and Pyrokinesis. Using the body to move objects is more energy efficient than using telekinesis. Since their body acts as an 'anchor' for the mind, destruction of the body means a loss of access to psychic powers. Creating a psychic effect further from the body uses more energy, proportional to distance. (Probably the square of distance).

New mind fragments can control up to $0.0664\, \mathrm {m^3}$ of material (thats about human sized) and each century they can grow between 20% and 30% larger (volume). A new mind fragment starts anchored to a $0.1\, \mathrm{m^3}$ of suitable material at a temperature of 450°C. The alien mind requires a bare minimum of 1220 watts of energy, but 1500W is the recomended minimum. The energy requirements of the brain increase by an average of 20% every 50 years. New mind fragments can borrow energy from their 'parent' if needed. Assume that their methods of gathering energy from the sun/ambient heat are only 1% (see Edit below) efficient. Each immortal alien needs enough room to gather energy for itself and to defend its energy gathering area. More power is better young immortals will need to defend their mineral deposites and collection areas from older immortals that want more energy and 'real estate'. For the sake of the question, energy is in demand.

I can forsee these immortal aliens building sun pits (?) that focus light and heat into a small area.

Would the Sqare-Cube law prevent them from growing past a certain point? When would population become an issue? Which of energy absorbsion or living space become an issue first? How would their civilisation form itself? What other issues might they run into from being immortal and having these psychic powers?

Edit: As per my coment on Murphy's answer, newborns have a heat-to-energy efficiency of 20%-30% which stays constant for the first century but then drops to 1% after about a miilennia. This (correctly and awesomely) means that "the oldest, largest and post powerful would also be the most greedy".

  • $\begingroup$ To know about population concerns, you'd need to tell us where they live and what resources they have access to. $\endgroup$
    – zeta
    May 20, 2015 at 7:05
  • $\begingroup$ Removed For questions that require answers based in hard science, not magic or pseudo-science tag, as it's fundamentally incompatible with the premice. I think reality-check, which is in-story-universe contextual, is what you wanted. $\endgroup$
    – JDługosz
    May 20, 2015 at 7:12
  • $\begingroup$ "Stone or metal" contradicts "only rock" $\endgroup$
    – JDługosz
    May 20, 2015 at 7:15
  • 2
    $\begingroup$ Energy can be absorbed as heat sounds very wrong according our knowledge of physics. We can extract energy from a difference of temperature, but there is not even a theoretical way to get energy out of heat alone. $\endgroup$
    – SJuan76
    May 20, 2015 at 11:24
  • 1
    $\begingroup$ @SJuan76 It says they use the energy differential with their home dimension. So I guess that dimension is the cold end? $\endgroup$ May 20, 2015 at 15:58

5 Answers 5


ok, so they must remain solid.

"The alien mind requires a bare minimum of 1220 watts of energy, but 1500W is the recomended minimum."

"Assume that their methods of gathering energy from the sun/ambient heat are only 1% efficient."

" A new mind fragment starts anchored to a 0.1m3 of suitable material"

These statements combined are problematic, they imply that they need to absorb a constant flow of a minimum of 150,000 watts as newborns. .

That's a lot of energy. Focus that much on anything with a surface area of only 1.3 meters (cube with a volume of .1 meters ^3) and it may be problematic. Even assuming it's being sucked away into some cold pocket universe near the centre this is going to be tough to avoid the outer surfaces melting or turning to gas.

115.4 kW per m^2 is a lot.

that's about ~~ 85 × electromagnetic energy flux of the sun on Earth (solar constant) and ~20 times the electromagnetic energy flux of the sun on mercury.

Even if your newborn is made of copper, hammered flat and painted black they're going to have trouble not starving even in direct sunlight on mercury.

You might want to up that efficiency from 1% unless you want energy problems to be really brutal.

lets assume they can use any metal. metals and minerals with an extreme melting point like Tungsten or Tantalum hafnium carbide(melting point of 4,215 °C) are going to be some of the most valuable and fought over comodities because they allow for maximum heat tolerance while copper is likely to be popular for the young and poor since it would allow fast absorbtion at lower temperatures.

So surface area is the important thing.

Can they store a large quantity of energy? Can they change body?

If so older, rich immortals are likely to have "feeding bodies" that look like big CPU cooling fans made of Tungsten or similar high-temperature material which they could submerge in vats of liquid iron to feed as much as possible and combat bodies optimised for durability and strength.

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If they can't change bodies or store a lot of energy then they'll likely go with the Tungsten bodies but with more practical shapes and perhaps lunglike pumps for when they want to have a "meal" of heat to pump liquid metal across fanlike internal surfaces.

But that's for the old and powerful who can control copious supplies of energy.

The younger ones are going to struggle more. the very poorest will simply bask in the sun with cobbled together mirrors focused on themselves in rock bodies and expend the minimum energy at night in an attempt to not starve.

The "middle class" might have metal bodies and perhaps arrays of mirrors focused on vats of molten salt.

Extreme cold will be a potent weapon, exhaust an opponent and drench his body in LN2 and he may not even have enough energy to reclaim a body.


"each century they can grow between 20% and 30% larger (volume)"

"The energy requirements of the brain increase by an average of 20% every 50 years."

Along with declining efficiency this would mean that as they get older their requirements increase faster than their volume so eventually they would starve but could put it off or a long time by turning themselves into vast constructions of heat fins submerged in molten metal. So not truly immortal.

  • $\begingroup$ I will admit that the figure of 1% was pulled out the air, 20%-30% might be better for newborns... Hmm what if their energy absorbtion efficiency declines as they age? eg: Starts high at 30% but after their first century (hopefully after they have a nice reserve) it starts to decline until finallt it dips to 1% after a millennia. Does that make sense? You mention changing bodies, sounds like ritual suicide to take advantage of reincarnation, which makes sense in horrifying and awesome way. I am undecided. $\endgroup$
    – amziraro
    May 20, 2015 at 13:08
  • $\begingroup$ declining efficiency could work. It would also mean that the oldest, largest and post powerful would also be the most greedy. I like it. $\endgroup$
    – Murphy
    May 20, 2015 at 14:34

Would the Sqare-Cube law prevent them from growing past a certain point? When would population become an issue? Which of energy absorbsion or living space become an issue first? How would their civilisation form itself?

Unfortunately I think this premise:

The immortal aliens prefer hot rocky planets, like Venus and Io (Jupiter's Moon)

Isn't what would actually happen. Once they achieved space, your species would be far better off to simply stay there instead of going back to a planet. Unlike humans - who need crazy things like ecosystems and air - your aliens are perfectly happy floating around the asteroid belt, and it offers a lot of advantages.

  1. Space - in the sense that they get a ton of room. Instead of fighting over the pitiful land area of a planet, your aliens can now spread out over entire planetary orbits. This gives them access to a massively increased amount of energy.
  2. Gravity - namely, the lack of it makes their psychic abilities a lot more powerful, and largely eliminates the square-cube law.

I envision that the aliens would create giant concave mirrors to focus solar energy, then nestle their actual "body" in the center. This also gives them a backup if their body is accidentally destroyed - they can take part of the mirror to reform. They could also use parts of these mirrors to communicate across the solar system, flashing messages to each other by slightly modifying the refraction or angle of the mirror.

Elders will want to be as close to the sun as possible, to maximize energy. Younger aliens will need to be further from the sun, slowing their development. However, this offers the possibility for an economy.

As resources grow scarce (asteroids mostly used up) you need to go further and further from the sun to find more. Elders would offer young aliens time in their mirror collectors (probably fractions of an orbit) in exchange for raw materials. So you'd end up with Elders closest to the star, with truly incredibly large mirrors - some might even be able to counter gravity and turn into Statites. And out from that would be increasingly more numerous but younger aliens, all trying to compete and create larger collectors, and trading/bartering energy for useful components to increase the size of their mirrors.

So basically, a race that naturally forms into a Dyson Swarm.

What other issues might they run into from being immortal and having these psychic powers?

I have a suspicion/hypothesis that immortality is an evolutionary dead end. On earth very few organisms are immortal, and most of those are very simple compared to a human being. The more advanced ones that I'm aware of (such as lobsters) have another mechanism that limits their lifespan, so while they're technically immortal in practice they aren't going to live forever.

The problem, as I see it, is that immortality is selected against on a species-wide level. There's a common misconception - I think stemming from the phrase "survival of the fittest" - that evolution is about creating the most powerful, fittest individual. But that's not the case at all. Evolution is more about which species are best adapted to their environment, and over long enough periods of time, that requires flexibility. Because environments change.

But an immortal species is in a trap. They've gone for more powerful, immortal individuals, but that means they've stopped - or slowed - how fast they evolve as a species, which reduces the chance that they'll be able to adapt if/when conditions change.

This makes me think that for an immortal sentient to evolve, they need to have some other mechanism that either 1) makes them functionally not immortal, like lobsters, or 2) they need to be able to adaptable/flexible as individuals, not just as a species.

So you can't have immortal elder aliens who are hidebound and reactionary - they need to be forward-looking individuals who can change tactics and strategy as the situation demands, giving up cultural momentum if the situation demands it. Maybe even evolving themselves as required, the equivalent of conscious gene manipulation.

  • $\begingroup$ Re immortality as a dead end: maybe time is different in their home space, and 100 years is a season for them. Maybe they don't have programmed cell death kind of thing, but stopped dying so much once they found our plane, got into space, or something. $\endgroup$
    – JDługosz
    May 20, 2015 at 18:52
  • $\begingroup$ There is always the story of the phoenix, Once there old the will elect to die and be reborn. Dying being the only way to combat the declining returns on solar collecting $\endgroup$
    – Mellester
    Jul 21, 2018 at 16:43

Eventually, the elderly would basically have to fling themselves into the sun for energy to meet their requirements. They would have to move closer to the sun, on a slow but regular basis to meet energy needs.

The biggest question is how much heat can there bodies actually and minds actually handle. A temperature of 450C is basically a lifeform that needs to exist near lava on a planet. At what point do there bodies or minds simply melt or burn up?

They would have to form a shell around the sun at the minimum safe threshold.


The adherence to normal energy ideas makes this proper SF with a modified universe. That is, you can be strict about applying your rules and forming plot points through their limitations and side effects. Keep up with that as a defining concept.

Because of that, it makes sense to ask about square-cube law and a few of the other points you ask. How are the golem bodies being animated? not muscles or hydrolic jacks in the limbs, and it is those things that have strength proportional to the cross section area and weight proportional to their volume. So no, the square-cube law does not apply.

How do they move? Somehow they can apply force to invidual mineral grains or rocks (through another dimension it seems) and thus move the components of the statue as well as being able to move an object directly. So why would he move or need limbs? Animating the rock of the arm to then push on the object is just wastful if they can move the object directly. Since you mentioned bodies made of (only) certain materials, there may be limits on what they can apply forces to or how effecintly they can do so or how easy it is for them.

So what is it about "rock" that is different from other materials? Maybe they like silicon atoms or particular chemical bonding configurations, so some minerals are better than others and simple material made of few kinds of atoms don't give them any grip from their home dimension.

How do they feed off heat? The home dimension or some different one could serve as a cold side to allow heat to flow. The hot environment of Venus all around their control region projection into our universe (whatever that is) can serve as energy that can flow into a different cold universe dimension. That means they can remove heat from their surroundings, an implicit power that can be directed for that effect.

Update: their whatever projection into our space doesn't feed by itself. It is the control over minerals that can work in the other direction, the thermal motion applying force to their "grip" and generating power. Naturally the entire volume of their body serves as energy-harvesting apparatus, not just the surface.

What limiations arise: they may have a capacity on how much they can grip. So materials inefficient for gripping consumes the capacity but is hard to control and is less efficient at feeding. They want most efficient mineral types, and highest temperature that allows said minerals to exist.

Living space or energy absorbtion being an issue first? Insufficient data. How much space does their projection into our reality take? If that is their power source, then they can be smaller in hotter environments, explaining their preference. Also they can push the minerals that exist there, but not ice, methane, etc. so they would be powerless on a comet.

So to quantity the answer, you need to set values for energy needs and gripping efficiency re feeding off heat. Maybe gripping more stuff uses effort, so larger bodies require more energy. If the feeding flux is less than the overhead, they are losing energy to control more.

If they need a particular heat flux to live, be alert, be happy, etc. that would give a sustainable resource level to each world. Can they go inside the planet and soak up heat there? Why not the sun?

Why do they want to move physical objects around? Do they make chess pieces or something? It's not for feeding or manipulating their environment for living conditions.

  • $\begingroup$ You have raised some very good points here that i will address i further in my question, quickly however: I ask about the Sq/Cb law because they absorb energy via their 'skin' and having larger bodies expends more energy and they also need a body to absorb energy. They are not omniscent either, their level of awareness is limited by the size of their body. They can also only control solids, slipping into the centre of a planet or star would destroy their body and they would not be able to gather more energy. I will edit my question to reflect these points. Thankyou! $\endgroup$
    – amziraro
    May 20, 2015 at 7:53
  • $\begingroup$ I think that the entire volume of the body would be absorbing energy, not just the surface. The thermal motion on the mineral grains that they are "holding" and can move by appling forces can work backwards as a generator, given a cold dump too. Ok, that explains the need for bodies and limiting environmental conditions. $\endgroup$
    – JDługosz
    May 20, 2015 at 8:05
  • $\begingroup$ I have edited the question to deal with some of the points you have raised. Also: "The adherence to normal energy ideas makes this proper SF with a modified universe" -- That is the intention, the 'Astral projection', 'psychic powers', etc is mainly because I am really bad at naming things. This is my first time doing serious world building and not just handwaving things, heh, hopefully I will get better :D. $\endgroup$
    – amziraro
    May 20, 2015 at 9:07
  • $\begingroup$ Try different "dimensions" as a trope. They live in a different space and reach ours via a 4th spacial dimension. To modernize, look at braneworld cosmology theory. They live on a parallel brane separated from ours by a few millimeters across the bulk. $\endgroup$
    – JDługosz
    May 20, 2015 at 10:21

@murphy's answer about heat sinks makes me think. I suggest that the entire volume of gripped minerals (since they're being held through the 5th dimension), but that removes the heat from it which must be replentished from the surface.

They may have a working volume made of minerals that they optimally grip, as well as they can obtain. But that is connected to other material with good heat conductivity or adaptors to withstand harvesting hotter sources then their main mineralmcan handle.

If they can't directly grip pure metal at all, they need limbs and digits made of the controllable stuff. These may be ad-hoc pseudopods, or maybe well-practiced limbs are easier.

They don't have to be contiguous. A digit may be on the outside of layers of non-controlled matter, as long as it's in range. It can even be loose, hovering near by. Imagine a detachable hand! Hovering uses constant energy that a piller supplies for free passively, so it's used sparingly. They can make their bodies into tools for constructing their extended bodies and environments.

I hope you run with this, and write an interesting story like Robert L Forward's aliens. A zoölogy treatment would be an interesting microfiction.


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