DaddyHoggy wrote:Switeck wrote:Current time has to be estimated/measured by first figuring out where the ship is at then figuring out the time based on objects that are multi-light-years distant and thus viewed as they were multi-years earlier. And considering Oolite's limited "radar" range, I think it's safe to assume ships don't have telescopes with a high enough zoom to clearly see ship-sized objects from light-years away. So for the clock's corrected time to be accurate, it has to be based on something changing at a regular rate yet large and/or bright enough to be resolved/measured clearly. So it's not reasonably likely to be anything human or alien made -- power output would have to be outrageous even by Oolite standards and if viewed from 100's of light-years away...it would also have to be in continual service for 100's of years.
I know how such time estimates can already be done without first building remote super-objects. It would be very hard to do in practice...but my guess is their relative inaccuracy would probably be so great that they'd be worthless for anything more accurate than what year or month it is "back at Earth". That's certainly not good enough to explain Oolite's strangely accurate auto-correcting clock in interstellar space after a misjump.
How about in Interstellar Space - which is normal space just a long way from anywhere - the ship's clock triangulates on the various (weak) signals from all the system clock updates traversing the cosmos from all the surrounding systems' witchspace beacons - perhaps measuring red shift and somesuch to confirm position and to extrapolate time accordingly...
Read up on the signal strength of the Voyager 1/2 probes at their current distances. That's a very tiny fraction of 1 LY. The witchspace beacons certainly are "louder" than that, but I doubt part of their purpose is for deep interstellar navigation. Even if they were, they'd need to be immensely strong RF emitters or gravity wave/space bending to even be detectable at interstellar distances. But assuming they are used, you'd have to know your current location accurate down to less than a light-minute (which would imply micro-arcsecond angular measurements, or at least 4 orders of magnitude more accurate than the best telescopes now and probably more accurate than even light passing through the near-vacuum of space would allow) and then back-calculate the current time based on probable distances to these distant objects.
Much stronger natural sources generating a near-perfect signal would be better candidates.
http://en.wikipedia.org/wiki/Pulsar
"Because neutron stars are very dense objects, the rotation period and thus the interval between observed pulses is very regular. For some pulsars, the regularity of pulsation is as precise as an atomic clock." ...
"Initially baffled as to the seemingly unnatural regularity of its emissions, they dubbed their discovery LGM-1, for "little green men" (a name for intelligent beings of extraterrestrial origin). While the hypothesis that pulsars were beacons from extraterrestrial civilizations was never taken very seriously, some discussed the far-reaching implications if it turned out to be true."
While pulsars are (hopefully!) not beacons made by extraterrestrial civilizations, they may be used as beacons out of convenience.
"turbulence in the interstellar gas causes density inhomogeneities in the interstellar medium (ISM) which cause scattering of the radio waves from the pulsar. The resulting scintillation of the radio waves—the same effect as the twinkling of a star in visible light due to density variations in the Earth's atmosphere"
Which is why such distant observations are probably not accurate enough to synchronize the ship's clock down to the second.