Mostly scientific stuff like astronomical observations — e.g. did this event observed at one telescope coincide with neutrinos detected at this other observatory.
Note I didn’t say they are more important than the Internet. That’s a value judgement in any case. I said that NIST level 0 NTp servers are more important to these use cases than they are to the Internet.
All these use at least GPS for timing
No, they don’t. GPS is orders of magnitude less reliable than the most up to date metric time synchronization over fixed topology fiber links.
I wonder why we bothered building GPS signal waveguides into the bottom of a mine then. Clearly we should have consulted the experts of hacker news first.
Losing NTP for a day is going to affect fuck-all.
I'm not even sure why you're trying to argue this. It's well established that Time over Fiber is 1-2 orders of magnitude more accurate and precise than GNSS time. Fiber time is also immune to many of the numerous sources of interference GNSS systems encounter, which anyone who's done serious timekeeping will be well acquainted with.
Trying to argue that neutrino experiments use GPS time, because they do?
I’m sure synchronising all the worlds detectors over direct fiber links would… work, but, they aren’t.
Unless you are trying to argue internal synchronisation in which case, obviously, but that has absolutely zero to do with losing NTP for a day, the topic of conversation.
The deployments are still obviously limited, but this is something you can straight up buy if you're near a NIST facility [0]. I believe the longest existing link is NJ<->Chicago, which is used for HFT between the exchanges.
[0] https://shop.nist.gov/ccrz__ProductDetails?sku=78200C
I doubt that very much. GPS time integrity is a big deal in many very important applications -- not the least of which is GPS itself -- and is treated as such.
Yes, an individual fiber distribution system can be much more accurate than GNSS time, but availability is what actually matters. Five nines at USNO would get somebody fired.