We pride ourselves that every human being is slightly different. We have a unique face, unique fingerprints, unique voice, all of which are so distinctive that we can identify each other with them. Animals have the same uniquess (ask any herder or vet), and that is true not only for large animals but small animals and insects too. There is great individual variation among the tiniest creatures. And now we know that individuals vary because their genetic code varies by individual; no two chromosomes are the same.

The non-living world is the same. Among the inert, each individual specimen varies. Famously, no two snowflakes are identical. No two crystals of any substance is 100% identical. Their uniqueness is derived from slight differences in the environment they are grown in. Tiny imperceptible variations is temperature and purity of substance will generate differences in the crystal.

As far as we can see in the macro world, no two objects are exactly the same. Every tree is unique. Every rock is unique. Every cloud, every lake, every river. Every planet and every star in the galaxy is, to the best we can determine, unique as well.  No two worlds will be alike.

But down in the micro world we have a different assumption. The current orthodox dogma is that every atom of an element is exactly the same. All oxygen atoms are identical.  Of course, we know that atoms are not the indivisible bits we onced believe them to be, but are in fact composed of many sub-particles. But the orthodoxy is that these subatomic particles themselves are identical. All protons are the same; all quarks are the same.

It is very unlikely that the Law of Universal Uniqueness does not apply to the atomic world as well. The hard fact that the quantum level is almost defined by uncertainty means that there must be variation between entities. No two oxygen atoms could be the same because their very borders are uncertain. No two iron atoms are the same because none of their protons, electrons and neutrons are the same either. My bet is that as we continue to probe the sub-atomic world we’ll come to see that there is a large variation between atoms and sub-particles. And that as in the human-scale world, this uniqueness matters. The variation is meaningful, not just trivial.

In all real things the Law of Universal Uniqueness applies. In fact, this will be one way to detect reality vs a simulation. If all items of a type are identical — at any level, particularly the base level — then you are in a simulation.