Going to be a different atom once you walk near. Or temperature changes, the wind blows, and so on.
We’ll need to give each atom a unique ID. That would solve the problem.
Let's start with electrons. I've got SN001 here with me, but I haven't been able to find any others...
IPv8 is accepting RFCs
Earth has about 2^170 atoms. If we ignore the core and mantle, focusing on the crust, surface and atmosphere, we should be able to cram it into IPv6. Even if we add a couple planets and moons in the future. At least if we stop giving each person 18 quintillion IPs just because we once thought encoding MAC addresses in the lower 64 bits was a good idea.
Addressing isn't really the big issue with IPv6. The main issue is that moving to mobile networks means all its assumptions about how routing will work are wrong, since you don't want to lose IP connections when you move across cell towers.
There are 10^80 atoms in the universe, therefore 266 bits are enough to give each a unique identifier. Due to how computers work maybe we can do two numbers: a 32-bit type or area code and a 256-bit counter. Or perhaps we just combine them into a single 272 or 288 or 320-bit number.
You're going to run into problems with quantum mechanics and the non zero amplitude that two identical hydrogens swap place.