It is too easy for me to default to "Solar Years" or "Earth Years", with residents referring to the standard time and date system of Mother Earth. But this seems to be too arbitrary and Earth-centric. It seems to me that residents of a future galactic community might use a more standard and generic unit of time, such as the rotation of the galaxy around the core.

I would like to hear the ideas of this fine community, and see if we can come up with something that seems easy to use yet non-arbitrary.

Well it could be measured from the Big Bang, but the numbers needed would be awkward. And with the universe speeding up in its travels, very dicey indeed to calculate constantly.

Suppose there is some deep pulse in the black matter or black energy or something? They keep time by that?

I've often pondered the question myself. Also how useful such thing would even be since problem of distance versus time traversing distance seems to be so...disconnected.

If you have wormholes, black holes, or "subspace" to travel through...how would you reconnect with realtime on the other side? How would such a ship and its passengers reset their watches?

And if you have time dilation while you travel...how certain would you be of exactly how long you were out of "normal" time?

I'd think one of the first things a ship would do upon re-entering normal space would be to check universal time. How? Now that's your question, isn't it?

Radio the nearest point of civilization? But to get the time exact, they'd have to know how far they were distant from the transmitter responding so they could account for the time lag between when the response was sent and they received it as they were traveling (quite fast) either towards the point of origin or away from it.

Without instantaneous communications what's the point of a universal set time?

I only say that because I think some get caught up in the details and forget the goal.

That said, my feeling has always been one of translation. Its unlikely your characters use modern day English, but your readers do. So, say your characters speak Garglespeak, and use the "pulse" for their second. Since, you're not writing in Garglespeak, your using--essentially--a translation. Thus, you don't have to say pulse. You can say "10 seconds."

Or to put it simply, a translation includes the conversion of time and distance measurements into something the reader can understand.

And the reader wants to understand what is going on. No one picks up a book and says, "Gosh, I hope this really confuses me."

If you don't use standard English measurements, please make them clear.

Don't bother to explain them, either. I've seen that, and hated it. I don't want to be doing math while I'm reading, trying to understand exactly how long it took in terms I can understand.

arriki, you make good points. I was imagining, perhaps ignorantly, a system of space travel using some type of space-bending drive, with it's own set of issues and pitfalls, but otherwise make travel over large tracts of space generic. I didn't want to bog down the story with useless and annoying physics. :P

Unless this is just a huge pet peeve of yours I'd leave measurements in metric or english units, the reader will assume that local measurement is being "translated" into units they are familiar with or won't notice at all.

We already do this on space missions where day and night have little relative meaning, but the human body is on a 24 hour biologic clock. As people adjust to their local environment there biology will modify as well. Several hundred years on a planet with a 48 hour day/night cycle and our internal clock will slowly adjust so that it is the norm to sleep 12-16 hours and be up 32-34.

The other reason for keeping traditional units is that the pre-existing history of the colony will be in terran units, so they would more than likely continue to use those units for recording additional history and events. It's been over 2000 years since the last time we had a major overhaul of our calendar, it's not something we do that often.

Here in America, each person and each town had their own time based on noon their time. Clocks visible between two towns might have a different time on each side so the towns could see what time it was there.
The problem was that railroads had to schedual their runs to avoid crashing into each other and different times was a problem. The railroads chose to divide the country into time zones, the actual noon in the middle of the time zone, so that entire tracts of the country could be traveled under the same time.
I would assume that a galactic transportation system would come up with a method for knowing what date and time it really is, no matter where they were in the galaxy. Using features noticeable from any eigth of the galaxy would be used for timing in one way or another. One would note angles between certain galaxies or halo star clusters, and then the measurement of their selected feature and have a good idea where they were and what date it really was. they might know when certain super novas happened and would pick out what condition those novas were, and know approximately when they really are, since the light might travel a hundred thousand years to reach them and they got there in a year.

But scientists still use it. Why? Cuz scientists have always used it. So if you want something other than standard time units, you need a solid *reason* why it is *necessary* in your world, is all I'm trying to say. Just because it makes slightly more sense to have new units doesn't mean it would happen.

On the other hand, if, like creating time zones for trains, you really do need a Galactic standard, you could set up a transmitter on Earth broadcasting "Earth-Time" to the rest of the Galaxy. Assuming every settlement knows with good precision exactly how far away they are from Earth, they could then detect the signal, compensate for light-travel-time for the signal to reach them, and then they would know exactly what time it is on Earth, and use that as the standard.

At least, as a scientist, that's the most likely idea that popped into my head first. After all, if you have the technology to actually travel to other worlds in our Galaxy, you're definitely going to know exactly how far away they are, by that point. And even if you only know Earth Time to the nearest day, I doubt spaceships from here to Betelgeuse are going to be leaving like twice a day? Or you can make that part of your story "due to uncertainties in the measurement of Earth Time on other worlds, ships can only use any given spaceship-track once a week, to avoid possible collisions." or something.

Hmmm. Now, say, there was this ancient civilization that set up such a signal broadcast millions of years ago. Whether they did it for this purpose or not, the human civilization might use it for that. But, once again, how will the initial signal, the time zero start time reach the more distant colonies? Back to the same problem. Instantaneous some kind of communications, that's what you need. Or something that broadcasts a lot speedier than mere light speed.

[This message has been edited by arriki (edited October 04, 2007).]

Like the rotation of a hydrogen atom (the electron passing around the nucleus)

You could then turn it into a decimal system

10h is ten rotations (very, very, very short amount of time)

10mh is ten million rotations (very, very, short amount of time)

For interplanetary travel, What matters is the local time at the place you're visiting, and the apparent time as seen by the observer (i.e., character). Both of those can be calculated, but nobody will actually do it themselves. Think about airplanes today: Flying East to West, where the time difference is X, and the flight time is Y, the Arrival Time A = Departure time D + Y - X. When traveling West to East, it's A = D + Y + X. But what I tell people who are going to pick me up is, "it says on my ticket that I depart Newark at 9:50 and arrive in Las Vegas at 12:03." The airline did the calculations for me. Ships will be able to do that in space, too; the railroads could have done it as well, but didn't have computers to make the calculation easy. (We have time zones in part because we invented trains before we invented computers.)

Investments: never thought about that. When Jeff on Zorg 9 pays his first installation on his Bose Galactic Headset II, he beams light to his bank on Earth to make the transfer. Since Zorg 9 is 10,000 light-years away, the interest compounds for 10,000 years between the "send" and the "receive" of the payment. Doesn't work, so I'd suppose that investments would be more concrete: "at the completion of a trading run, you'll receive back 10-fold what you lent me." I imagine that if you looked at mercantile systems before the rise of bankers, you'd find plenty of models for that.

As mankind expands from earth, they are not going to be jumping hundred thousand lightyears at a time. Instead, they will go twenty five light years, ten light years, thirty light years, in small jumps. They will be able to see what the distance is from home, and easily figure out how long they had traveled. Remember, we have had radio broadcasts for nearly a century. I doubt we will jump more than a hundred lightyears away in the next two centuries. We will likely use the communications from earth as our measurement as we travel, at least for a while.
We will gather other methods of time calculation as we expand so an earth centered time system would be easy to develop. You are a thousand light years from earth, you leave your colony planet and appear ten light years away, the signals from the colony will give you your distance and time, along with astronomical measurements, You now can reset your universal clocks to match real time.

AS for the merchant trade, The merchant buys the product outright, then travels to the destination and trades what he has for what they have, then returns. The merchants themselves, back in the middle ages, were the ones who became the bankers. They had the funding to loan money.

quote:

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You now can reset your universal clocks to match real time....
...Even a trip of four light years would likely be ten years round trip. A lot happens in ten years.

---

A trip of four light years might appear to take ten years to people on the planets, but that means that it would appear to the merchant as though he had taken a very much shorter trip. He might set his watch to January 1, 2100 on Earth, travel to Alpha Centauri (4 light years away) for a few days, load up his stuff, and travel back to Earth for a few days, and then reset his clock to January 3, 2110. Since the disparity between his apparent time and Time on Earth would be so great, either the computer would take care of it for him or he'd just reset his watch on arrival.

That implies some interesting things. For instance, much trade is based on relationships, but those relationships would be difficult to develop and maintain when people kept aging much faster than you did. The merchant would leave with an order from Tom and return -- a few days or months later in his own apparent time -- with a shipment for Tom's great-grandson.

There's another problem. What would hold its value over such time spans that it would be worth the ship owner's and crew's time to carry back and forth? I think Cherryh touched on that in her merchanter novels.

Gold? Water? Novels/movies? Knowledge? Certainly not the latest Bose headset. Sperm? Animal fetuses frozen? Chocolate? Yeah, have to have good ole Earth chocolate!

rstegman said -- he merchant buys the product outright, then travels to the destination and trades what he has for what they have, then returns.

But imagine -- John on Earth is going on a trading venture to far Betelgeuse. On Earth before he leaves he stocks up on what? It'll be a thirty light year trip there which means a ten years on board ship? What sort of goods can he predict that they will want thirty years from now? Even if he gets the trading news from the ship that just returned from there -- that's thirty years out of date already. And what to bring back to Earth thirty years from now? He had to be an awfully canny trader and have a good crystal ball besides to figure all that out. Or whoever at IBm who's footing the bill for his voyage, needs such.

Also if you have FTL then you don't need to worry about relativity since Einstein, in that universe, was wrong :-)

When travel is at light speed and under it is doubtful there will be anything that warrants the time needed to ship it, the product will more than likely be produceable at the other end. If it can't be produced at the other end, but is an essential item, then they should have brought a larger supply during the original colonization.

Now if you have FTL this changes, since the time commitment becomes dramatically less.

This also changes if the human lifespan increases dramatically.

For galactic time and keeping track of a universal standard I'd suggest uses quantum clocks or some such, you could also exploit this for instantaneous communications. A piece of quanta divided shows a connection to the divided parts that does not respect distance. One part in Australia that is acted upon, the piece in New York reacts as well.

A communication device based on this principle could concievably act as FTL radio or clock.

One is not going to get a mazeratti on the colony, nor would one get other exotic, name brand materials. Patterns and tooling for high tech equipment might also be sent. along with machinery that are cutting edge science or medicine. By its nature, a colony is not going to have that stuff.

Several years ago, I did a couple discussions about whether, with our present technologies, be able to leave earth for the stars within a hundred years. I assumed technology and science advances we know we will have, like robotics and maximim speed computers. I also discounted sciences and technology we might not ever have such as cold fusion or working fusion ractors.
My conclusion, wsa that unless we were going to travel at light speed, which I also discounted for certain reasons, It would have to be generational ships and would really have to be something were we were abandoning the planet to make it even plausible for the expense involved. I assumed that a century was the absolute maximum the journey could last and still work.
All the problems, solutions, and possible incidents that could happen over the entire journey from the time someone starts to push for the project to the time the colony lands, would make for several thousand stories without taxing the imagination.

One should note that no time in earth's history did colonization pay for itself to the mother country. It was always a drain. I don't see stellar colonization being any different.

But - for time...how about time "buoys"? They'd be easy to "ping" once you exit your Faster-Than-Light travel or wormhole or whatever. They'd be notated on ... er, star charts or something so that the captain of the ship would be able to look up the specific signal from that buoy and then let the computer figure out what time it was. I learned on vacation this summer in Cape Cod that all the lighthouses up and down the cape (and father) have their own unique "signatures" - for instance (hopefully I'll remember this right) the Highland light, aka the Cape Cod Light, is white light, 5 seconds, white light. The Race Point Light is ... white light white light 11 seconds, white light (I think.) Woods end is red light, 12 seconds, red light. You get the gist. This could be done on a larger scale in space, I think (and I think it's nifty to use this sort of real-world/nautical idea in space travel because it's something that people who know will think is nifty, and those who don't will just think you're smart. LOL)

You all have given me a lot to think about, and a lot of good information. I can also see how working through these issues can lead one down a road where no writing is ever accomplished, only research!