Yes, but Google Spanner is not open source, so it's not so easy to actually look at it. But what is known to public is that Spanner relies on perfectly synchron

Yes, but Google Spanner is not open source, so it's not so easy to actually look at it. But what is known to public is that Spanner relies on perfectly synchronized atomic clocks within their datacenters, called TrueTime. This solution is very special and does not work for other databases in general.