How to keep time across many planets

[DougFarren]

Here's a problem I haven't seen discussed anywhere before (if I'm wrong please redirect). The basic question is: "How should time be kept on multiple planets?"
At first glance this might seem like a simple question with a simple answer - "Duh, just divide up the planet's day into 24 hours and go from there!" I disagree.

Let's take an extreme example: Humans have colonized a new world. Measured by our standards the planet rotates once every 36.5 hours and has a 451 day year. If you simply divide up the day into 24 hours you end up with a second that's a little over 1.5 standard seconds long - unacceptable. What's the solution?

One possibility is to continue to use our standard length of time and to simply declare the day to be 36 hours, 31 minutes, and 18.5 seconds long. At the strike of 3621:18.5 a new day begins. Confusing - yes, but it could work.

Now let's complicate things even farther. As an author, I find it boring to write a book where humans are the only life forms in the galaxy. So now what happens when multiple species, each with their own unique timekeeping system, decide to colonize a new planet together? How should time be kept? It's doubtful they would use hours, minutes, and seconds. I doubt they would use weeks and months either. Their method of keeping time would be just as alien as they are to us.

One more thing to consider in this discussion - in any star-spanning civilization the need to compare events across space will occur. The news might report that Earth's President was newly elected on February 10th, 2155 (Earth time). The population of a human colony world might want to know what that translates into in their local timekeeping system. How can so many planets keep their historical records in synch? (Sorry Einstein, I'm going to ignore simultaneity issues for now.)

Here's one proposal but it's far from perfect: All the races agree to a central timekeeping standard. Each planet maintains two timekeeping systems; local and galactic.

As a side note - a savvy business traveler making stops on multiple worlds would have to have a sophisticated, programmable timekeeping device in order not to be late for his meetings!

I can be reached at author@dougfarren.com if you want to initiate a side discussion.

[Grokl]

Earth time would be standard across the galaxy, unless we had to negotiate a common standard with an alien race.

Each planet would also have its own time based on rotation and time it takes to move around the system sun. Time would start when the first human landed on the planet being year 0.

[DougFarren]

My problem with Earth time as a standard is pointed out in the third paragraph which states: "One possibility is to continue to use our standard length of time and to simply declare the day to be 36 hours, 31 minutes, and 18.5 seconds long. At the strike of 3621:18.5 a new day begins. Confusing - yes, but it could work."

You can't simply declare a day to be 24 hours long either since that changes the basic definition of how long an hour, minute, and second are.

There really isn't a simple answer. Consider another extreme possibility - we colonize a planet with a VERY slow rotation period. If the planet took 64 hours to rotate and we humans tried to live there as if it was Earth you would end up staying up for over a day and then be expected to sleep for another day. If you truly used Earth time then you would just ignore the day/night cycle which might be even more confusing.

Perhaps the best solution is actually to use Earth time and ignore the planet's natural cycle. I leave the group to discuss this and the ramifications of doing so.

[Grokl]

I did not mean that the new planet(s) would use earth time. Earth time would be standard when speaking of time between people on different planets.

Each planet would also have its own time based on rotation and time it takes to move around the system sun. Time would start when the first human landed on the planet being year 0.

Edit: So if you have a watch you would have planet x time and earth time on it (digital ;-) ).

[Window Bar]

Good topic... though I was hoping you would hand me the answer all tied up in ribbons and bows.

My current WIP faces this issue, and it has been one of those little beauties that gets SAFLed (Set Aside For Later). If the perfect concept happens to come my way, I'll be ever-so-generous and share it.

-- WB

[Chuffalump]

Actually it's already been done. Star Trek did it with it's stardate format. Each planet's time is not only different from every other planet but is different depending on where you are on the planet, i.e. depending on the longitudinal location.

So......each planet has a time based on an Earth(ish) format. A day split into an arbitrary number of hours composed of an arbitrary number of minutes with an arbitrary number of seconds. Actual numbers don't really matter since the locals will get used to it fairly quickly.

Running along side this is a stardate system counting up in decimal earth years from a recognised time point. Such as the first landing on the moon or something. Humans don't need to be able to interpret the stardate unaided. Every timepiece runs the local system and the stardate system. When messaging another planet time is automatically converted from local to stardate. The receiving system converts the received stardate into their local.

If you want to have a common frame of reference in a spoken communication then keep one part of your measurement system in common. You could use the 'second' and format your times similar to Vernor Vinge (ksec, Msec etc). e.g. 'I'll call you again in 1.5ksec'

It might seem cumbersome at first but humans are very adaptable and would soon get used to thinking in the new formats.

[Chuffalump]

The problem with verbal communications between planets is the potential narrow window of availability. I can visualise giant displays in company headquarters showing multiple important planets in real time, so that it's easy to tell if the location you want to talk to is on the night side or not.

[Steven L Jordan]

Since the original designation of hours, minutes and seconds was a rather arbitrary one in the first place, I would suggest replacing it with a more universal measurement based on a set "second," possibly divided into subsets by an easy-to-understand base system like base-10 (which could still be difficult for 8-fingered three-limbed aliens).

Using this system, each planet would choose the numeric total of seconds that constituted a day, starting the count over at midnight. By that count, a Terran day would be approx. 86,400 seconds long, a Martian day would be 88,775 seconds, etc.

Combining this with a stardate brings up problems, however: If a stardate is uniform, it will begin and end at different times for every planet using it. So you'd have a locally-determined day measurement, and your planet's stardate measurement, and the stardate measurement would change to the next day at a different local time every day (today the stardate ends at 82,240, tomorrow it ends at 83,360, the next day it ends at 84,480, etc).

It would be something like keeping track of time according to our 24-hour clock, combined with the timing of the phases of the Moon. I daresay the only way to make a system like that work would be using local time as the standard, and using sophisticated devices to monitor and deduce present and future time and date settings at multiple planets at once.

And that's not even getting into how to synchronize them over distances that can only be covered by time-dilating FTL travel...

[NickeeCoco]

The problem with verbal communications between planets is the potential narrow window of availability. I can visualise giant displays in company headquarters showing multiple important planets in real time, so that it's easy to tell if the location you want to talk to is on the night side or not.

I don't see why not. It's what we do already with cities here on this planet. You can get watches with times of other cities on them too (and a lot of them are not digital either). As someone suggested already, why not a watch that does other planets too.?

[Chuffalump]

I'm guessing here, but I said 'I can visualise.....'

Stick with an intergalactic text message. It's easier.

[kshRox]

Perhaps the best solution is actually to use Earth time and ignore the planet's natural cycle. I leave the group to discuss this and the ramifications of doing so.

If we ignored the environments natural cycle wouldn't this create havoc with our circadian rhythm?

[NickeeCoco]

I'm guessing here, but I said 'I can visualise.....'

I was agreeing with you.

[Chuffalump]

It's all to do with the mental tone I hear in my head while reading. When I read "I don't see why not" now, it sounds totally different.

[ebusinesstutor]

Our new alien overlords will give us their new time standard when they arrive....

[Aldroud]

I like to imagine a future when time is defined in kiloseconds (1000 seconds). A second, defined as 10^43 plank seconds, is the standard measurement of time (local).

Standard periods of time we commonly use would be something like this.
"I need 300 seconds of your time" = 5 minutes

3.6 kiloseconds is approximately 1 hour, old standard. Redefine the hour to be 4 kiloseconds. That gives 21.5 hours in a day. Round it off to 20 hours.

So, one 'day' = 80 kiloseconds.

Metric clock, 20 hours. Ignore the environment, we're technological beings - we use lightbulbs in the dark.

Local time units can be whatever the locals feel like, but now you have a universal time.