The “land of giants” thought experiment

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mick haupt 98gLyuDFNAs unsplash

The “land of giants” thought experiment is a thought experiment about 

how it might be possible to reduce the size of humans and

other living things in order to increase the size of inanimate objects.

 It was proposed by 17th-century philosopher René Descartes in his “Meditations on First Philosophy”.

Descartes asks what the world might be like if humans were larger.which point does fullinwider intend to make with the “land of giants” thought experiment? 

He suggests that, if humans were larger, the Earth would be smaller: 

“Suppose that some god were to increase my size

while keeping that of everything else unchanged and that he brought me near to the sun; wouldn’t I heat up?”

 And, if humans were larger, they would also be more massive

“Suppose some god were to make me larger again and turn me into a giant; wouldn’t I become heavier?”

Descartes uses this reasoning to deduce that there is a relationship between the size of something and its physical properties. 

Thus he argues that a being cannot become any more physically extended, heavy, bright, dry, cold, hot or capable of acting

 from a distance from any physical cause if its size remains unchanged.

Descartes suggests that it is much more fitting to suppose that the world is made up of much greater quantities of much smaller things than much larger things.

 In other words:

Either we may presume all bodies to be infinitesimally small and infinitely numerous; or we may suppose them all to be equally large and infinitely few. 

It is not therefore necessary…that nature took infinite pains to make the infinitely small: she did not however..

.make the infinitely great either unnecessarily large or relatively infinitesimally small.

Furthermore, in this second case, if we suppose the world to be made up of infinitely small particles, 

we can understand how it is possible for there to be a great number of bodies (infinitely large and infinitely few in number), for example: 

It is also possible that there are many worlds; they may even be infinitely many;

 though they are not [otherwise] infinite in number [since there is a finite quantity of matter]. 

It makes no difference at all whether the matter contained in these worlds is much larger than that contained in ours or much smaller.

 For we can easily conceive that it might be much larger or much smaller than ours.

Descartes concludes with the remark,

 “We are therefore convinced that the bodies of animals are composed of parts which are themselves materials of bodies ever smaller, 

and thus capable of being divided to infinity.”

Physics experiments have shown that space can be curved.

 The most notable example is Einstein’s theory of general relativity.

 According to general relativity, space-time curves around large concentrations of mass-energy (e.g., stars or planets).

 It is not known whether there are any regions in our universe where it is possible for space to be “flat”, i.e., without curvature.

Physicists generally regard this as a fascinating question, but for the purposes of this thought experiment

 we will ignore curvature as such and confine ourselves to what is said to be simpler: the concept of “flatness”.

As Descartes pointed out, if there were infinite quantities of matter, then it would be possible for objects to cover the entire universe (“infinitely far”). 

This is clearly an absurd notion. 

Therefore, we can reduce (or increase) the size and mass of objects without changing their physical properties (e.g., physical extension and mass). 

If we do this, then there must be some limit on how much space can be covered by material objects without them touching each other.

 This limit is described as “flatness”.

If the universe were “flat”, then it would be possible to fit an infinite number of objects in a finite space. If this were the case, 

then there would be no edge or boundary to our universe. This absurd notion can easily be dismissed.

 Descartes’ suggestion that the world could be made up of much smaller parts cannot therefore be correct,

 since it leads to an infinite number of objects occupying a finite amount of space.

Therefore, either the universe is curved or it has a boundary or edge (i.e., is not “flat”).

Since we cannot assume that the world is “flat”, we can assume that it is curved.

 Descartes’ suggestion that the world could be made up of infinitely many infinitesimal particles also suggests 

that it is curved, since a flat surface does not have an edge or boundary.

This leads us to a number of interesting paradoxes. 

A famous example is the “interminable universe” paradox: if a universe was infinitely large,

 then there would be no reason for it to come to an end, and therefore there would be no reason why it could not cover all space. 

Therefore, there would never cease to be new matter (“infinite” materials) at any point in time from any possible point of view. 

However, if the universe were infinite in size, then an observer in some finite region would never be able to see beyond his own immediate surroundings.

Another example is the “exploding universe” paradox: If a Universe was infinitely large at a particular point,

 then it would have to exist for all time—a single event which could not be described. 


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