The Last POWER1 CPU on Mars Is Dead (opens in new tab)

Interplanetary internet designs and peering are interesting problems to think about though.

https://en.wikipedia.org/wiki/Intergalactic_Computer_Network

This is actually not that a big deal, in many countries, like Afghanistan and Iran, people observe 3 different calendars for different purposes and they all drift from each other! That is, 1st Jan (Georgian) is not always 24th Jaddi/Dey (Afghan/Iranian - Solar) nor 7th of 7th Jumada i-ula (Lunar/Islamic)..

So people use calendars that look like this for each day: https://en.wikipedia.org/wiki/Rumi_calendar#/media/File:1911...

Fantasy use case: Asteroid mining and traffic control. If you want to boost prepared asteroids to an orbit closer to Mars and you had a space station / spaceships to watch out for, different mining companies might want a clock protocol, a request buffer, and a map instead of synchronously planning, timing, and verifying each and every asteroid orbit change in a central location ("What do you mean you were using Earth time and not correcting for relativity??").

Setup a transmitter at earth which emits a signal at uniform intervals containing current time (seconds since kanye west's marriage). An observer can then deduce current time if it knows where it is. I don't think relativistic dilation would effect this method.

With multiple such emitters synchronized with each other, one might even be able to 'triangulate' the current time. (I haven't worked out any details)

I hear this argument a lot for why we cannot have a universal time standard but it's a weird cyclic argument because it suggests the measurement of time has to be constant while acknowledging that time is relative. So why can't we have a measurement that is also relative?

For example it could be n "ticks" where mass and speed is at a predefined value and allow for decimal points to account for people travelling faster (for example). This means people's life expectancy (for example) could not be measured in "ticks" because "ticks" is used for time synchronisation rather than measuring the passage of time and those who are only interested in the passage of time can use local time zones just like we do now with UTC for keeping equipment synchronised but local time zones for scheduling our human lives.

https://en.m.wikipedia.org/wiki/Proper_time

The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency {\displaystyle \Delta \nu _{\text{Cs}}} {\displaystyle \Delta \nu _{\text{Cs}}}, the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1.

There's no preferred frame of reference, meaning that any frame of reference could work, but you can derive one from the cosmic microwave background if you don't like picking something too arbitrary.

Im not sure pulsars are actually that precise and predictable to not require regular adjustments to equate local times, but it would provide a standard anybody could utilize as long as they could keep an eye on it.

Of course it would break down if someone broke light speed, either with wormholes or some unknown technology, but as long as you are below lightspeed then there shouldn't be any problems.

It's even useful as a consistency model for some distributed systems.

An example we already deal with is GPS satellites orbiting Earth. Their clocks tick a little bit slower on account of how fast they're orbiting, and tick a bit faster on account of being further up Earth's gravity well. The gravitational effect is stronger, and the net effect is that a GPS clock advances an extra 38 microseconds over the course of a day (as measured by a clock on the ground).

http://physicscentral.com/explore/writers/will.cfm

So when you try to standardize on "seconds since the epoch," the inevitable question is "Seconds according to who?"

Vernor Vinge got there way ahead of you, If you haven't read his books and given the way this community slants you are missing out.

> Take the Traders' method of timekeeping. The frame corrections were incredibly complex - and down at the very bottom of it was a little program that ran a counter. Second by second, the Qeng Ho counted from the instant that a human had first set foot on Old Earth's moon. But if you looked at it still more closely ... the starting instant was actually about fifteen million seconds later, the 0-second of one of Humankind's first computer operating systems.

https://en.wikipedia.org/wiki/International_System_of_Units#...

"The SI unit of time is the second (s): The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom."

I'm not a physicist, but I think that's a universal definition - the rate of the periods should be constant everywhere in the universe.

So universal seconds are actually very easy to nail down. Dates are always a little more troublesome. Perhaps seconds since the start of the big bang would be a possibility.

But one thing I am sure of -- we would make good friends ;)

Universal time is, of course, impossible in a relativistic universe, but (no sarcasm) that doesn't prevent us from trying, and getting to "close enough to work with for reasonable amounts of effort". Just as only a small portion of the world works on UTC directly right now, this time standard would be something computers would translate for people. Traveling at 80% the speed of light away from Earth in Earth's frame means you wouldn't want to directly use the resulting definition of a Standard Second for human time, but computers would be able to work with it.

I don't know what the orbiters use, presumably some variant of Julian day.

Also I think the confidence interval for instrumentation looking that far ahead would be so big comparative to current/possible local solutions, we're probably better off doing something in the Solar System instead.

One advantage of synchronizing to some reference in the Solar System, and maybe setting clock boosters as floating checkpoints in space, is we will always be able to find our way home :)

The fact that this phrase of yours is literally true, and it's already 2019, makes me very sad.