Time slots

Hey,
I am trying to learn about ethereum 2.0 and currently I found this website: https://ethos.dev/beacon-chain/
Are there any other detailed resources for the actual algorithms being used?
Also, a little question. The article says that there is a 12 second time slot? How does a node measure the time though? I guess it can't use a local clock…
submitted by /u/ethmaniac
[link] [comments]