I think you’re right: seconds will end up being the universal unit to measure time. But whether or not local times will be synchronized with the time back on earth depends on whether we use FTL travel and communication.

In early America, Boston, New York, and Washington D.C. all were on different time zones, off by a few minutes each (bell towers helped everyone within earshot be synchronized) – it took several days to travel between them and people didn’t have very accurate clocks. The need for synchronized time came with the invention of trains and the telegraph.

If it takes 20 years to send a message to a colony, no one’s going to care if the clocks are synchronized. But it will matter if we have faster-than-light travel.

I’m pretty sure i’ve sat around and thought about this sort of thing before, but i never went anywhere in researching it. Nice work.

@ levinalex:

You know, it’s funny but “A Deepness in the Sky” and “Accelerando” are on my Amazon wish list. I don’t remember correctly, but one of them might be in my most recent order that should arrive at my house any day now. If not, they are definitely going in on my next order.

@ levinalex

This page goes into some more datail and gives more references and seems relevant. (and Accelerando is also a very nice book)

The concept seems to be called Metric Time

You should read Vernor Vinges “A Deepness in the Sky”. It’s a great book and he depicts a society which uses exactly these units (“back in a ksec” is actually used there)

@ jambarama:

Well, I’m assuming you would be using an atomic clocks. So elliptical orbits and all that stuff shouldn’t matter. You base it on the rate of decay of a cesium 133 atom.

But yes, errors will be made but then again you can periodically sync your atomic clocks. Isn’t that what we do now? We have authoritative ntp servers and distributed networks that allow us to make sure we are all more or less on the same page.

Also, I’m not sure how using a second would affect the risk of error. After all, we do use seconds right now – they are our basic time measurement unit. Just instead of using SI prefixes we lump seconds into minutes, hours, days, months and etc. But at the end of the day, we still have to do that bullshit with the leap second to make sure we don’t fall out of sync with the sun rises and sundowns.

@ Chris Wellons:

Oh, I did not think about that. I’d assume we would have some way of compensating for the time dilution. I mean we can calculate this based on the velocity, mass of the ship and length of the trip, no? So you can semi-accurately say that a ship time second is n standard seconds.

What about relativity? Time passes at different rates for different observers. You might have to pick one frame of reference and base your time off of that. If you’re traveling in a very fast spaceship and you say, “This project will be completed within a megasecond” where it’s measured by the passage of time on Earth, that could turn from a week into 2 minutes.

While I’m sure relativity screws this up in someway, I wonder if using such small units in isolation increases the risk of error. I mean, if your measure of a second is off by .001, it isn’t a big deal when you’ve got other measures to check it against. Like it takes 60*60*24 seconds before the sun comes up again tomorrow. If patterns are more irregular on other planets (say they’ve got an elliptical orbit, or two suns), a second measure off by .001 might not be caught, and it’d cause some significant disparities between planets. Maybe that doesn’t matter, but if we have to pick a unit to base all time measurements on, I’d prefer a larger one.