4 ms·

Or take a step back and look at the larger picture - devise a universe time that we can all adhere to where ever we are. Why remain earth centric when we're mak

Or take a step back and look at the larger picture - devise a universe time that we can all adhere to where ever we are. Why remain earth centric when we're making more and more steps away from earth?

omnicognate 4y ago
Unfortunately, Einstein threw a very large spanner into the works as far as that idea is concerned: https://en.m.wikipedia.org/wiki/Relativity_of_simultaneity https://en.m.wikipedia.org/wiki/Relativity_of_simultaneity.
- dotancohen 4y ago
  Then how about using the pulses of a distant pulsar to measure time? That should get us through to the next few centuries at least. The fine article mentions that Lunar atomic clocks could be placed in Lunar orbit. However, there are very few stable lunar orbits due to the numerous mascons near the surface. And station-keeping would affect the clocks' accuracy - not to mention that the tidal variations on the Earth side and far side will affect the clocks as well. And any Lunar-specific solution would be unlikely to scale to Mars, Mars' moons, asteroids, and interplanetary spacecraft. Thus reinforcing the distant pulsars' signal as the optimum solution for the time being that humans remain in the solar system.
  - helsinkiandrew 4y ago
    But aren't the pulses of pulsars affected by black holes and wouldn't the pulses arrive at Mars, Moon, Earth at different times anyway?
midoridensha 4y ago
Because it's impossible. There's no such thing as a universal time; it's all relative to wherever you are at that moment. Earth is small enough that relativistic effects between any two points are insignificant, but the Moon is far enough away that it'll be noticeable, though not that much. Anything farther, however, and it all breaks down. Within the system, it'll probably be "close enough" to have an offset between different places. If we expand to different star systems, though, it'll be impossible because they're moving in different directions.
atoav 4y ago
Ever heard of the twin paradox? There can be no absolute time, because time is relative to the observer. And if the observer is near to a big mass or moving very fast time passes differently for them.
bmacho 4y ago
I suggest that we should use a universal date system, and a local clock system simultaneously. The computers can change between them. Other solutions (using a universal time for local things, or using local time but adding leap microseconds here and there) all seem bad to me.

omnicognate 4y ago

Unfortunately, Einstein threw a very large spanner into the works as far as that idea is concerned: https://en.m.wikipedia.org/wiki/Relativity_of_simultaneity https://en.m.wikipedia.org/wiki/Relativity_of_simultaneity.

dotancohen 4y ago
Then how about using the pulses of a distant pulsar to measure time? That should get us through to the next few centuries at least. The fine article mentions that Lunar atomic clocks could be placed in Lunar orbit. However, there are very few stable lunar orbits due to the numerous mascons near the surface. And station-keeping would affect the clocks' accuracy - not to mention that the tidal variations on the Earth side and far side will affect the clocks as well. And any Lunar-specific solution would be unlikely to scale to Mars, Mars' moons, asteroids, and interplanetary spacecraft. Thus reinforcing the distant pulsars' signal as the optimum solution for the time being that humans remain in the solar system.
- helsinkiandrew 4y ago
  But aren't the pulses of pulsars affected by black holes and wouldn't the pulses arrive at Mars, Moon, Earth at different times anyway?

midoridensha 4y ago

Because it's impossible. There's no such thing as a universal time; it's all relative to wherever you are at that moment. Earth is small enough that relativistic effects between any two points are insignificant, but the Moon is far enough away that it'll be noticeable, though not that much. Anything farther, however, and it all breaks down. Within the system, it'll probably be "close enough" to have an offset between different places. If we expand to different star systems, though, it'll be impossible because they're moving in different directions.

atoav 4y ago

Ever heard of the twin paradox? There can be no absolute time, because time is relative to the observer. And if the observer is near to a big mass or moving very fast time passes differently for them.

bmacho 4y ago

I suggest that we should use a universal date system, and a local clock system simultaneously. The computers can change between them. Other solutions (using a universal time for local things, or using local time but adding leap microseconds here and there) all seem bad to me.