6 ms·
Can someone please explain to me what this is all about like I’m five years old?
by strimp099 5y ago
Can someone please explain to me what this is all about like I’m five years old?
- Groxx 5y agoTime is hard. By asking both super-microscopic stuff and stuff way out in space, you can now find out what time it is!
- bogomipz 5y agoOne is cesium? Whats the other stuff, way out in space?
- tadbit 5y agoGPS
- schwede 5y agoThe GPS constellation.
- jfrunyon 5y agoRubidium. Cesium atomic clocks are more expensive.
- baq 5y agoGalileo sats use these https://www.esa.int/Applications/Navigation/Galileo/Galileo_s_clocks https://www.esa.int/Applications/Navigation/Galileo/Galileo_... so, basically magic.
- loxias 5y agoYou think that's magic, check out optical lattice clocks. Blows my mind every time I re-read about them and accept "yes, this actually works".
- tatersolid 5y agoSome Pulsars have extremely stable frequencies https://www.nytimes.com/1983/02/09/us/pulsar-termed-most-accurate-clock-in-sky.html https://www.nytimes.com/1983/02/09/us/pulsar-termed-most-acc...
- vel0city 5y agoA person with two watches never knows what time it is.
- pugworthy 5y agoNah. They just figure out eventually one of them is kind of wonky and ignore it. Or maybe both are, so they end up just looking at the stove clock. Also you can't tell a story just with the Aesop ending - you have to tell the fable and END with that line.
- oblio 5y agoI can't find the fable.
- TecoAndJix 5y agoI found “Segals Law” https://en.m.wikipedia.org/wiki/Segal%27s_law https://en.m.wikipedia.org/wiki/Segal%27s_law
- oblio 5y agoAh, no, the misunderstanding was with something else. Apparently "Aesop ending" is a keyword/crossword definition. It means "the moral of the story" :-)
- teddyh 5y agoSo what I’m hearing is “Get three or more watches.”.
- foota 5y agoThe combination of a time and guaranteed error bound can be used as a primitive in distributed systems. You can get timestamps from requests coming from different systems and relate them in a meaningful way. At least, in a false negative fashion. E.g., if A occurs at T + 100ms with 1ms uncertainty and B occurs at T + 105ms with 2ms uncertainty you can conclude that A happened before B. This does not allow you to always establish an order (e.g., if there is overlap) but this isn't always necessary. For instance if instead you are B and you want to have something occur after some time A with uncertainty A_uncertainty, then you can sleep until B with uncertainty B_uncertainty such that B - B_uncertainty > A + A_uncertainty.
- bigsparky 5y agoYou must know some pretty smart five year olds!
- foota 5y agoThat doesn't say L5? /s I missed that part :-)
- gnu8 5y agoNone of this has to do with Amazon though. I am very uncomfortable with Amazon (or the others) pretending that they invented precision timekeeping and that it is a special feature only they have because it seems like a lot of people believe it and build systems that rely on an API that is proprietary to a cloud vendor rather than just installing ntp.