# Unit of time **URL:** \ **Category:** Factual Questions\ **Created:** [September 4, 2003, 5:13pm UTC](https://boards.straightdope.com/t/unit-of-time/199555 "2003-09-04T17:13:27Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![insider](https://avatars.discourse-cdn.com/v4/letter/i/bbe5ce/32.png) [@insider](https://boards.straightdope.com/u/insider)\ **Post date:** [September 4, 2003, 5:13pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/1 "2003-09-04T17:13:27Z")
What is the longest Unit of time measurement? What is the shortest? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [September 4, 2003, 5:29pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/2 "2003-09-04T17:29:32Z")
The shortest that makes any sense is the Planck time. The longest would be the age of the Universe. ---
**Author:** ![DarrenS](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DarrenS](https://boards.straightdope.com/u/DarrenS)\ **Post date:** [September 4, 2003, 6:08pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/3 "2003-09-04T18:08:32Z")
I read somewhere (I know, the ubiquitous “somewhere”) - I think it was in Scientific American on reflection - that current thinking, or maybe research, is indicating that time may _not_ be quantized after all, instead flowing continuously - anyone heard about this? The best cite I could find was [this](http://www.sciam.com/askexpert_question.cfm?articleID=000A03B0-6000-1C71-9EB7809EC588F2D7) - they are sitting firmly on the fence. The longest conceival measure of time - **QED** - did you mean the age of the universe _up till now_, or the total age of the universe, from Big Bang to - what? - proton decay? Heat death? One thing seems certain - the road ahead stretches way further than the road behind us. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [September 4, 2003, 6:19pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/4 "2003-09-04T18:19:23Z")
Did someone here say that time _is_ quantized? Also, I think the OP was asking about a unit of time that has a name, not just the longest span of time that we can imagine. There’s a millennium, that’s the longest that I can think of offhand. But that’s just a prefix meaning “thousand” added to a word that means “year.” If we allow that, then we could go “yottaennium” to denote 10^21 years, but I don’t think that’s fair. The logest fundamental unit I can think of is “year.” ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [September 4, 2003, 6:31pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/5 "2003-09-04T18:31:14Z")
IIRC there are some words in Hindu theology for enormously long time spans. My Websters says an eon/aeon is an unmeasurably or unimaginably long time or a billion years, take your pick. ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [September 4, 2003, 6:41pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/6 "2003-09-04T18:41:50Z")
**nanoseconds** microseconds milliseconds seconds minutes hours days weeks fortnight months years decades centuries millenia **aeons** One aeon = 1.0 × 10^-14 nanoseconds =) ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [September 4, 2003, 6:44pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/7 "2003-09-04T18:44:12Z")
The definition of infinity might suit the purpose as the longest measure of time. > [@](#): > > Main Entry: in·fin·i·ty > Pronunciation: in-'fi-n&-tE > Function: noun > Inflected Form(s): plural -ties > Date: 14th century > 1 a : the quality of being infinite b : **unlimited extent of time** , space, or quantity : BOUNDLESSNESS > 2 : an indefinitely great number or amount \ > 3 a : the limit of the value of a function or variable when it tends to become numerically larger than any preassigned finite number b : a part of a geometric magnitude that lies beyond any part whose distance from a given reference position is finite \ c : a transfinite number (as aleph-null) > 4 : a distance so great that the rays of light from a point source at that distance may be regarded as parallel ---
**Author:** ![chappachula](https://avatars.discourse-cdn.com/v4/letter/c/d2c977/32.png) [@chappachula](https://boards.straightdope.com/u/chappachula)\ **Post date:** [September 4, 2003, 7:01pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/8 "2003-09-04T19:01:19Z")
there is a measure used by astronomers called a “jiffy” its the smallest fraction of a second ever considered to be relevant in science–a decimal point followed by 43 zeros and a 1. try saying “one to the minus 43rd of a second”-it’s easier to say “a jiffy”. It is (I think) the amount of time it took the Big Bang to create the basic quantum particles that later coagulated into the protons and electrons. (Something like that, anyway. I ain’t no quantum physicist). (Actually,–I dont know how you define “unit”–but I’m not sure that it could be called a “unit” of time, because it is only used for one purpose-defining that one aspect of the Big Bang theory. I dont think scientists measure other events in jiffy’s.) ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [September 4, 2003, 7:26pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/9 "2003-09-04T19:26:31Z")
The Planck time (which now uses Dirac’s constant instead of Planck’s constant as a base) is roughly ~10E-43 seconds and was one of the Planck or natural units which were created in order to try and get rid of the arbitariness of units. It’s also the distance that quantum gravity is thought to take over from classical general relativity. The Planck era was the first 10E-43 seconds of the universe, which cannot be described without a theory of QG. ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [September 4, 2003, 7:29pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/10 "2003-09-04T19:29:50Z")
Time’s not quantitized as far as is known, that the Planck time is the shortest meaningful measurement of time currently is not the same as saying that time is quantitized. ---
**Author:** ![biqu](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@biqu](https://boards.straightdope.com/u/biqu)\ **Post date:** [September 4, 2003, 8:22pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/11 "2003-09-04T20:22:34Z")
The [number of years](http://home.earthlink.net/~mrob/pub/math/numbers-10.html#l_p0_207_758) in the Jain unit of time known as a _shirsha prahelika_ is on the order of 10[sup]207[/sup]. In contrast, the approximate [age of the universe in Planck time units](http://home.earthlink.net/~mrob/pub/math/numbers-9.html#l_p0_878e60) (smaller than a year by many orders of magnitude) is on the order of 10[sup]60[/sup]. ---
**Author:** ![UncleBeer](https://avatars.discourse-cdn.com/v4/letter/u/977dab/32.png) [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)\ **Post date:** [September 4, 2003, 8:56pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/12 "2003-09-04T20:56:34Z")
Longest = an afternoon at my mother’s house. Shortest = the period leading up to that. ---
**Author:** ![picunurse](https://avatars.discourse-cdn.com/v4/letter/p/7bcc69/32.png) [@picunurse](https://boards.straightdope.com/u/picunurse)\ **Post date:** [September 4, 2003, 9:15pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/13 "2003-09-04T21:15:44Z")
I have always used the excuse of, unlike other humans, living in non-linear time, for my chronic tardiness. Are you now telling everyone else is moving here too!? I just can’t have it… I knew I shouldn’t have followed that rabbit!. ---
**Author:** ![RogueRacer](https://avatars.discourse-cdn.com/v4/letter/r/7ab992/32.png) [@RogueRacer](https://boards.straightdope.com/u/RogueRacer)\ **Post date:** [September 4, 2003, 9:16pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/14 "2003-09-04T21:16:02Z")
I once heard on a game show (Jeopardy I think) that the shortest unit of time is a **moment**. Of course that’s not quantifiable, but if it’s on a game show it has to be right! 🙂 ---
**Author:** ![Dogface](https://avatars.discourse-cdn.com/v4/letter/d/9d8465/32.png) [@Dogface](https://boards.straightdope.com/u/Dogface)\ **Post date:** [September 4, 2003, 10:08pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/15 "2003-09-04T22:08:05Z")
> [@](#): > > \*Originally posted by alterego \* > nanoseconds You forgot pico, femto, atto, etc. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [September 4, 2003, 10:21pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/16 "2003-09-04T22:21:23Z")
> [@](#): > > \*Originally posted by alterego \* > \*\*One aeon = 1.0 × 10^-14 nanoseconds =) \*\* Eh? Think you mistyped. 1.0 x 10[sup]-14[/sup] nanoseconds is a really tiny length of time–1.0 x 10[sup]-24[/sup] seconds, or almost double the Planck time. On the other hand if you meant 1.0 x 10[sup]14[/sup] ns, that’s only 100,000 seconds or about 27.7 hours. ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [September 4, 2003, 11:00pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/17 "2003-09-04T23:00:30Z")
10E-24 is not almost double the Planck time it’s just under a trillion mutiplied by a trillion mutplied by a million times bigger!!! ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [September 4, 2003, 11:02pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/18 "2003-09-04T23:02:08Z")
Oops now I’ve made a mistake it’s ~10 trillion trillion times bigger ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [September 4, 2003, 11:02pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/19 "2003-09-04T23:02:58Z")
> [@](#): > > \*Originally posted by MC Master of Ceremonies \* > \*\*10E-24 is not almost double the Planck time it’s just under a trillion mutiplied by a trillion mutplied by a million times bigger!!! \*\* Yeah, I realized that after I’d posted. I was looking at the exponents when I said that, obviously. ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [September 4, 2003, 11:06pm UTC](https://boards.straightdope.com/t/unit-of-time/199555/20 "2003-09-04T23:06:55Z")
an easy mistake to make 🙂 [Next page](https://boards.straightdope.com/t/unit-of-time/199555.md?page=2)