I believe that a universal calendar will be needed, since the days,
months and years in the colonies will be different of ours here in Earth.
And also, what can be used as reference for a universal calendar,
while it will be only in our MW, its right, but at universe level?
Somebody has some idea?

Yes, sure.

I would suppose that we would have to work with an independent (as far as we can tell) measure, called the second. Its standard international definition is:

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.

See http://www1.bipm.org/en/si/si_brochure/cha...1-1/second.html

This definition can (as far as we know) be used universally. The only remaining factor is the reference time. This is arbitrary, though, and probably a pollitical issue. It can for example be defined as 00:00:00 on 1 January 2000 according to the Gregorian Earth-calendar (some more significant date might be preferred).
See Wikipedia: Gregorian Calendar

Seeing that a sencond is such a very short time, we can possibly make use of longer time units based on the second, for example kilosecond, megasecond, gigasecond, etc... An average Earth-year is then 31.556952 megaseconds. An average Earth-day is 86.4 kiloseconds. We might as well define a specific Earth-year and a specific Earth-day and do away with leap years, if this is possible. I do not have the necessary astronomy knowledge to know whether such definitions can be made. Does the Earth complete each revolution around its own axis in exactly the same time always? And revolutions around the sun?

Oh, and chuck months away. Using seasons should be a fine replacement. We would still need weeks, because humans require at least one rest day for each 6 days of work (as far as I know, this has been "proven" emprically).

I think we should call it the Scientific Calendar. Then we can use the terms BS and AS for indicating dates before and after the Scientific Calendar reference.

Very good idea Fracois!

the BS/AS sounds good, but...
...This would make we forget two thousand years of..., well we have our history.

Thanks, really fine the kilosec, megasec point, I had not thought about this.

Maybe we don't need a universal calendar. Would it actually matter if we thought it was Friday the 11th of February when the Centaurans thought it was Tuesday the 45th of Octember?

The easiest thing would be to let each planet define its own length of day and year, then base their calendar on, say, the day the planet was first colonised. If you're visiting a planet, just ask them what the date is before you arrive.

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No, don't worry. We don't have to forget about history just because of something as silly as a calendar change.

Of course you are correct. There is no need for a universal calendar other than convenience. But, I am sure you can agree that it might make things easier if everyone used the same calendar. Then you would always have an absolute reference frame when you discuss history with other neighbours in the galaxy. But sure, this is not a necessity. At least, I don't think so.

I've been giving this some thought now. I am wondering about an easy system for using a calendar based on seconds. Even I, as a scientist, would need a computer to translate the date to something meaningful.

We are used to a simple system based on days. We all know the definition of a day: one cycle of day and night. But unfortunately, the same definition on another planet in another star system won't result in the same length of time, especially if the planet is in a system with 2 suns. So if we want to use a universal time reference, then how do we simplify the system? Is it possible?

I guess we should still have local calendars with days, weeks, seasons and years when we find ourselves on some planet (if it is applicable to that planet). The only difference would be the date/time we use when documenting history, or anything else. If I write something down with a date attached, it does not really matter on what day of what year it happened. What matters is whether it happened before or after some other event.

I think this also answers the question of whether a universal calendar is necessary. It might happen that politics between two planets require date comparisons (eg. for patents). It would then be appropriate to have a universal calendar.

When you are in space, there are no days or years anyways, so a second-based calendar might even make more sense.

So I'll make one suggestion for simplification. Say something happens on the 42nd day of the 5th year for some planet. Obviously, you can't really translate that to senconds without discarding some information. You would for example be able to translate it to within 86.4 kiloseconds if you work with 24h days. We could standardise the usage to round it down to 50 kiloseconds and say the event happened on UT (Universal Time) 122 M 350 k (or perhaps even UT 122.35 M). Some other planet might have 200 kilosecond round days, giving something like UT 122.4 M. Of course, you can record the exact seconds if it is available.

I agree that we should adopt a universal calander. One based on scientific study and observation rather than some arbitrary time constraint set down by some emporer's whim or some man's religeous beliefs. When it comes to science and technological development. I feel that keeping political, religeous and personall whims out of it is the only way to keep the purity of scientific study intact. Developing a universal calander that eliminates all this would be a huge step in the right direction. While we are at it, lets universalize the weights and measures systems too. Why does one country have the right to think they can have their own unique system while the rest of the planet is on another?

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Well, we already have a universal system for this purpose: the SI system. Some people just prefer not to use it, although I don't know the reason. Maybe it's just politics - in which case it will be very hard to convert (accidental pun here) them.

Have a look at http://www1.bipm.org/en/si/si_brochure/

Maybe each planet could have its own reference of time, to keep it simple for it's own inhabitants in regards to seasons and periods of rotaion, etc. The idea of a universal standard is good though. Why don't we just pull from Roddenberry and have a universal "star date". It might be 14:45z 17 March 2565 here on Earth, and 37:64z 50 Memtobruary 106 in colony D44Beta, but we can communicate and syncronize according to the fact that it's stardate 50032.7.

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This discussion has come up before, a while ago.

I think, in our galaxy, the 220 million years for one rotation might be a start, concentric rings out from the center could be sectioned off.

But I think calendars are, and always will be culturally relative, that is why so many are still active today.

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I don't think a universal calendar is a necessity, for two reasons:

1.) On the very largest scales, a universal calendar would be difficult to use because of the limitations of the speed of light, and because events in the universe for the most part happen on time scales vastly beyond human scales.

2.) On the local scale, I think it makes more sense for planets to devise local time scales than to impose a universal one. For instance, Greenwich Meridian Time would be meaningless on Mars, since it would fall back by more than a half-hour each sol. On the Moon, with a solar day almost thirty times longer than Earth's, universal time would be similarly out of whack.

In all these instances, I think it would make more sense to reduce local times to each other than use a universal calendar or time scale.

Just my two bits.

There doesn't really need to be a universal calendar that everyone uses. I suspect that by the time we are actually in need of such a thing translation software will obviate needing to put a lot of effort into the conversions.

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I suppose that for the time being, a universal calander is unnecessary. But as technology and space travel progresses, and the colonization of other worlds, whether it be the moon, other planets or other star systems. a universal time measurement will become a useful tool. I as an aviator for the past thirty years have found that using Greenwich Mean Time for all our takeoff, landing and reporting times is much more efficient than trying to figure out the local time. Although when we do land, we adopt to the local time for our off airport activities.

I think as we do venture into space, a system such as this will be adopted. A Universal time for space travel and then revert to local planetary, (or moon) time after you land.

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Imagination is infinitely more important than knowledge.
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The important things are those that you learn after you know it all.
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To coordinate observations of distant events from different widely spaced viewpoints it will be necessary to have some sort of universal time; this already exists, and is called UTC (Coordinated Universal Time)
http://aa.usno.navy.mil/faq/docs/UT.html
which is based on GMT.

In actual fact there is no real simultanity possible in different reference frames; but UTC is as close as it is possible to get.

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Yes that's true, but since conversion is easy you aren't restricted to having ONLY ONE such universal time for your calculations.

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One interesting and bizarre possibility is that if wormholes between distant stars were possible, they would effectively become time machines;

in a galactic empire connected by wormholes, a new type of time measurement becomes necessary- this is called Empire Time...

this essay gives a little taste of the mind bending possibilities involved
http://www.aleph.se/Trans/Tech/Space-Time/...ormholes.html#6

(we use a modified form of Empire Time at Orion's Arm, incidentally)

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Commerce would require a universal time. Efficient movement of resources between any two points requires the transport know the time to pick up and deliver the shipment. Rather than keeping 100 billion conversion rates between my star's time system and any other star's time system, I keep only the conversion from mine to universal, convert my time, and then transmit that my shipment should arrive at your dock at a specific universal time. You keep only the conversion for your local time to universal and back, and then convert the time I transmitted to your system and schedule your receiving staff accordingly. The only true local thing I would need to know is if the 45th of Octember is the Holy Day of Saint Alvis where all workers wear nothing but jock-straps and combat boots and fight each other in the streets weilding nothing but giant soft foam "we're #1" fingers as weapons in commemoration of the event that made Alvis a saint...

Asimov covered all of this in The Foundation series. He also pointed out that mankind has been living under a 24 hour day and a 365 day year for our entire existence (100,000's of years as H. Sapiens, and millions before that as older species), and this rythm is built into our body's cycles. Just because your new planet doesn't obey that time scale it doesn't mean your body will just switch to the new system over night. Those kinds of changes are evolutionary and take time. Therefore the universal time will be 24 hours in a day and 365 days in a year because that was the universal time where humanity began.

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