4 ms·
> 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 th
by kmoser 8mo ago
> 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.
- NoMoreNicksLeft 8mo ago>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 8mo agoFor the uninitiated: https://en.wikipedia.org/wiki/One-electron_universe https://en.wikipedia.org/wiki/One-electron_universe
- nivertech 8mo agoSo UUIDv∞ will be at least 536 bit long? And with group IDs, timestamp, etc. - 1024 bit long?
- Dylan16807 8mo ago> 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 8mo agoEven 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.
- zdragnar 8mo agoNew atoms form all the time, either through fusion or fission. The latter is happening right now all around you- either from potassium in plants breaking down, to radon gas that sept up from the ground, to carbon itself. All of these have unstable isotopes with half lives short enough to have at least a little activity near you. Given that constant change to the available combinations of sets, it would seem that a truly capable system would need to be practically infinite, no?
- Dylan16807 8mo agoNo, not every permutation. An atom gets to be in one larger object (recursively). Definitely no multiples. What would that even mean, also you would need unbounded space for multiples of just two atoms.
- kmoser 8mo ago> Definitely no multiples. What would that even mean, also you would need unbounded space for multiples of just two atoms. I have a list and I want to assign a unique ID to each list item. Each list item itself contains one or more items: 1. My umbrella [ID "a"] and my sunglasses [ID "b"] 2. My umbrella ["a"], my sunglasses ["b"], and my umbrella ["a"] List item 2 contains two references to my umbrella [ID "a"].
- Dylan16807 8mo agoSo in a physical sense of identifying things that's nonsense. And again if you allow that then lists of just one or two atoms can take up infinite storage space. That's a super obvious reject. It makes no sense to even try to accommodate it in an ID system.
- wavemode 8mo ago> 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.
- Drakim 8mo agoDon't they have different x,y,z positions?
- ForHackernews 8mo agoThat's unclear https://en.wikipedia.org/wiki/One-electron_universe https://en.wikipedia.org/wiki/One-electron_universe
- antonvs 8mo agoYes, but the issue is that they don't have identity. The idea of assigning unique identifiers to particles is doomed because, basically, "there are no particles, there are only fields" (https://arxiv.org/abs/1204.4616 https://arxiv.org/abs/1204.4616). Particles are how quantized fields present themselves when probed by localized interactions. In general, they're also observer-dependent. The idea of assigning an "ID" to an object reflects a macro-level notion of re-identifiable objects persisting through time. But at the quantum level, that kind of classical individuality - object identity - doesn't exist.
- kmoser 8mo agoJust 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.
- kbelder 8mo agoWouldn'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 8mo agoIf we're talking reality, sure. But you can also consider it a Gedankenexperiment.