[kmoser]

> A more reasonable upper limit might be to assume that every atom in the observable universe will get one ID (we assume atoms won’t be assigned multiple IDs throughout time, which is a concession). There are an estimated atoms in the universe. Using the same equation as above, we find that we need 532 bits to avoid (probabilistically) a collision up to that point.

This doesn't take into account that you will inevitably want to assign unique IDs to various groups of atoms (e.g. this microchip, that car, etc.). And don't even get me started on assigning unique IDs to each subatomic particle.

[wavemode]

> unique IDs to each subatomic particle

You only need one ID for each type of particle. Since the laws of physics dictate that the particles themselves are indistinguishable from each other.

[kmoser]

Just because a given particle is indistinguishable from another of the same type doesn't mean they are the same actual thing. If you are assigning IDs to each item in the universe for accounting/inventory purposes, you'll still want a separate ID for each particle.

[Drakim]

Don't they have different x,y,z positions?

[kbelder]

Wouldn't the minimum discrete unit be something that is capable of recording the ID? Or, if not, space somewhere would need to identify that that atom has this ID, which would take at least as much space.

In other words, the act of 'assignment' presupposes some mechanism of assignment, and at a certain level of granularity the information needed for that mechanism to function is greater than the information the system can store.

It would be like assigning each byte in a stick of ram a 32 bit random access ID, and trying to store the assignments in the same memory space. Memory addressing only works because we assume a linear, unchanging order.

[kmoser]

If we're talking reality, sure. But you can also consider it a Gedankenexperiment.

[Dylan16807]

> This doesn't take into account that you will inevitably want to assign unique IDs to various groups of atoms (e.g. this microchip, that car, etc.).

Sure it does. Those are not going to add up to a single extra bit.

[kmoser]

Even every possible permutation of every single subatomic element in the universe? Even if we just consider atoms, at 10^80 atoms in the entire universe, there are (10^80)! possible permutations, which is many, many, many orders of magnitude larger.

And this isn't even counting sets that include multiples of the same item; once you get into that territory, there really is no upper bound.

[NoMoreNicksLeft]

>And don't even get me started on assigning unique IDs to each subatomic particle.

If a neutrino oscillates between flavors, does it get 3 IDs? Or does it get a new ID with each oscillation?

Thankfully, we only need one electron ID at all.

[liamwire]

For the uninitiated: https://en.wikipedia.org/wiki/One-electron_universe

[nivertech]

So UUIDv∞ will be at least 536 bit long?

And with group IDs, timestamp, etc. - 1024 bit long?