If people were about 1 foot tall and weighed about 1 pound, would we ever have made a reactor or an atomic bomb? Because critical mass doesn't change, the scale of the project to mine and process radioisotopes would effectively be >100x larger than in our world.

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    $\begingroup$ Are these people still hominids? Or are they squirrelidians? Making big weapons whose sole purpose is to destroy other people might not even be conceivable for other kinds of sophont life. $\endgroup$
    – elemtilas
    Jun 15, 2020 at 18:12
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    $\begingroup$ By your scale argument mining even basic coal or ore would be colossal tasks as well, but they won't even get to the industrial revolution without those steps. Petroleum based industry won't work without similar grand scale projects, so just getting to the point they'd be able to consider nuclear power production would be unlikely (if you follow your logic). $\endgroup$ Jun 15, 2020 at 19:36
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    $\begingroup$ Don't forget the fact that the world could assumedly support vastly larger numbers of Lilliputians than humans. There would be more Einsteins, more Oppenheimers, and more Manhattan projects. Getting past the biology, that's a lot of potential genius. Cumulative need for power would probably end up the same, eventually, so the idea for nuclear power would be just as relevant. $\endgroup$
    – DWKraus
    Jun 15, 2020 at 19:37
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    $\begingroup$ The way the Chicago Pile was put together- Squirrels would have been perfect. "The reactor contained 45,000 ultra-pure graphite blocks weighing 360 short tons (330 t), and was fueled by 5.4 short tons (4.9 t) of uranium metal and 45 short tons (41 t) of uranium oxide. Unlike most subsequent nuclear reactors, it had no radiation shielding or cooling system as it operated at very low power – about one-half watt." $\endgroup$
    – Phil Sweet
    Jun 16, 2020 at 2:35
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    $\begingroup$ It would be hard for squirrel size humanoids to even handle fire. Given wax etc. they could work with a candle, but building a campfire, a forge for smelting metal etc. would be far harder for them than humans even if they had the intelligence. Developing the technology that comes before fission reactors would be far harder if it is possible at all. See also phys.ufl.edu/courses/phy3221/spring10/HaldaneRightSize.pdf $\endgroup$
    – Jim Baerg
    Jun 19, 2020 at 1:39

3 Answers 3



At the size of a squirrel, the human brain would be the size of a nut (well, some people ...). To develop our society we need a brain capable of holding billions of neurons.

Trying to compress all 86 billion neurons into a smaller space will require immeasurably longer sleep time, having no more space in the life span of mini-humans except for eating and sleeping.

We would not have the fire, the wheel, the writing, let alone a society able to create atomic technology.


You didn't say anything science-based! (=

Admitting some handwaving where the mini humans will have these conditions, they will form a society, something like the little ones at Gulliver Travels, the problem is only in the scale of the projects that they will be able to carry out.

Will they be able to work with metals, make forges, in order to build metal structures many times bigger than themselves, just like we build giant mining machines?

Per instance, this is a diesel ship engine:

enter image description here

It is also good to keep in mind that they will not have all the operations in our measure, the total necessary for the critical mass will be obtained within the capacity and technologies that they will employ. The energy demands they have will also be reduced.

With 1% of the mass and 1/5 of the height of average humans a Joule is equivalent to 500 "mini-Joules". 1 MWH for them is equivalent to 500 MWH for us. Other simpler sources will seem more plausible to them most of the time, unless they are at a technological level far ahead of what we are today.

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    $\begingroup$ +1 for the awesome picture, to which I will add that we have built some very large machines. Bucket wheel excavators, for instance, can be pretty freaking enormous. The idea of squirrel-sized people building something like a motor vehicle the size of a compact car (which, for them, would be around ten stories tall) isn't implausible if they have a need to do so. We can and do generally build up to the limits of material strength if we have a reason to do so. $\endgroup$
    – Matthew
    Jun 15, 2020 at 19:20
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    $\begingroup$ We don't know how many neurons are necessary to support complex abstract thought. By your logic, elephants or blue whales should be the dominant species on the planet... $\endgroup$ Jun 16, 2020 at 2:19
  • $\begingroup$ @LawnmowerMan I no went extend with it, if you wish, there more details here. $\endgroup$ Jun 16, 2020 at 2:47
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    $\begingroup$ Please don't forget that it humans were smaller, we would need at least somewhat smaller ships, therefore smaller diesel engines for them. $\endgroup$
    – vsz
    Jun 16, 2020 at 4:23
  • $\begingroup$ @vsz The size of waves won't change just because smaller creatures are traveling, so a small ship would be a bad idea. $\endgroup$ Jun 16, 2020 at 8:40

I concur with Halthawe's at first sight: why couldn't they? answer.

But Consider:
Squirrelmen, being only a foot tall and weighing in at only a pound have very different materials & technological needs. Being relatively light & weak, they could easily make vast yet structurally sound edifices from wood, leaves, and bronze.

They could make a steam train entirely out of copper, brass, and wood. They may never even come to use iron, to say nothing of any more advanced metals. The brass rails of a standard garden railway (No. 1 Gauge) can easily support a hundred pounds or more, whereas a scaled up brass rail could never support the weight of a steel & cast iron locomotive.

No. They never needed to get to enough of the intermediate technological points along the way. Even if the Squirrelmen discovered the physics & math that would allow them build The Bomb, they may simply not have the material to make it a reality.

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    $\begingroup$ Counterpoint: While it's true that they don't need iron or steel, possessing it would provide whichever side that has it an advantage in a war. I think it's fair to say that they would develop iron and steel. $\endgroup$
    – Halfthawed
    Jun 15, 2020 at 18:52
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    $\begingroup$ We could have made steam trains out of bronze and wood. But steam trains came very very much later than iron; the thing with iron is that it is vastly more abundant than copper and tin, which makes it so much cheaper: steel costs about 1/10th of the price of copper, and about 1/30th of the price of tin. The height of the miners is irrelevant, iron will always be very much more abundant and very much cheaper than bronze. $\endgroup$
    – AlexP
    Jun 15, 2020 at 19:55
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    $\begingroup$ @Halfthawed - I actually disagree with you on that. At the scale we're talking, neither bronze nor iron will make weapons that are superior to wood. A cocktail sword would be about the right size for a squirrel to wield. A squirrel probably could not heft a sufficiently large iron or bronze weapon to serve as a mace -- it takes a very powerful punch to subdue an average sized rodent (just watch a video of a cat going after a rat). I think their weapons of choice would be stabbers & slashers, and a sewing needle is no more effective than a toothpick. $\endgroup$
    – elemtilas
    Jun 15, 2020 at 20:46
  • $\begingroup$ @AlexP -- And wood is even cheaper and more abundant! At that scale, metal just isn't as useful as it is to us. $\endgroup$
    – elemtilas
    Jun 15, 2020 at 22:31
  • $\begingroup$ @elemtilas While I totatally agree with you, steel or copper have a fancy property that wood lacks: it doesn't burn when exposed to fire. Saying that they would never develop iron or steel because they don't need anything that resistant and heavy is like saying that we humans would never develop something as silk or plastic because it's not hard enough to make a weapon with them. There are many uses for many things, and an intelligent species will end using them all. $\endgroup$
    – Rekesoft
    Jun 16, 2020 at 9:46

Ignoring all the other issues caused by shrinking humans to the size of a foot, such as the fact that we'd be unable to function biologically and most likely wouldn't be intelligent to begind with...


It may be large relative to the 1 foot sized human, but it's still the same size compared to the deposits present on Earth, so the material is there, it just needs to be mined. A bit of extra work wouldn't slow down, say, the Manhattan Project from being developed.


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