Ask Ethan #30: Long-term timekeeping (Synopsis)

While friendship itself has an air of eternity about it, seeming to transcend all natural limits, there is hardly any emotion so utterly at the mercy of time.” -Robert Hugh Benson

If you were headed out into the Universe -- spaceship and sci-fi technology and all -- it simply wouldn't make sense to keep on counting time in Earth-days and Earth-years, would it? When you're no longer bound to our planet, and particularly if you're gone long enough, as our planet changes its orbit, it sure seems silly, doesn't it?

Image credit: American Physical Society, via http://www.physicscentral.com/explore/action/iceage.cfm. Image credit: American Physical Society, via http://www.physicscentral.com/explore/action/iceage.cfm.

But you still might like to know how much time has passed, wouldn't you? You'd like to have some way of tracking the passage of time in the Universe. Is there some sort of standard that's more universal than an orbit of a rock around a star? In this week's Ask Ethan, we take on perhaps the longest question of them all, and look at how to keep time for arbitrarily long times.

Image credit: © NASA / Goddard Space Flight Center / Dana Berry. Image credit: © NASA / Goddard Space Flight Center / Dana Berry.

Go and read the whole thing.

More like this

“Don’t be too proud of this technological terror you’ve constructed. The ability to destroy a planet is insignificant next to the power of the Force.” -Darth Vader Supervillains always disappoint me. With ambitions like murdering a single human, destroying a city, or endangering all life on the…
"For in the final analysis, our most basic common link is that we all inhabit this small planet. We all breathe the same air. We all cherish our children's futures. And we are all mortal." -John F. Kennedy After a great week over on the new Starts With A Bang blog, where we covered a whole slew of…
"We shall not cease from exploration, and the end of all our exploring will be to arrive where we started and know the place for the first time." -T.S. Eliot It's been a remarkably exciting week for science, and you've had a lot to say about our new articles at the main Starts With A Bang blog.…
“Every dreamer knows that it is entirely possible to be homesick for a place you’ve never been to, perhaps more homesick than for familiar ground.”  -Judith Thurman You'd think that landing on a comet for the first time, with all ten instruments functioning, and collecting more than two full Earth-…

I would think if they brought an atomic clock on board with them the time would still be earth based but what we're used to doing.

By Truthspew (not verified) on 28 Mar 2014 #permalink

Actually with the current definition of the second as "the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom." Time is very portable, and does not refer to the earth at all. As comment number 1 points out, if you carried such a clock with you you could know how much time has passed.
Note that the earth is a poor time keeper, at the micro level, we have leap seconds every so often to make up for irregularities in the earths rotation.
The larger question is if one travels off earth why keep the object with a duration of 86400 since that is directly tied to the earth, why not then go whole hog with a purely metric time system and talk about kilo seconds, mega seconds, and giga seconds. For example one might move to dividing time into 10 kilo second periods.

Lyle- the definition of the second applies on the geoid, meaning the surface of the earth. Gravitational time dilation would affect this in space (clocks would tick faster), though it would be a fairly simple adjustment to make.