# What is the shortest time measurable... **URL:** \ **Category:** Factual Questions\ **Created:** [January 14, 2013, 5:21am UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138 "2013-01-14T05:21:07Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![BunnyTVS](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BunnyTVS](https://boards.straightdope.com/u/BunnyTVS)\ **Post date:** [January 15, 2013, 11:21pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/21 "2013-01-15T23:21:04Z")
> [@ducati](#): > > Sorry, but the time between a woman saying “I do” and her realizing she’s given her last blowjob is roughly 1/4 “Panasecond”. Actually I think you’ll find that is one of the few examples of an effect preceeding a cause. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [November 19, 2016, 12:35pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/22 "2016-11-19T12:35:05Z")
We have [a new winner](https://www.newscientist.com/article/2112537-smallest-sliver-of-time-yet-measured-sees-electrons-fleeing-atom/): …[Physicists at Max Planck Institute of Quantum Optics in Garching, Germany] fired a near-infrared laser pulse, lasting just four femtoseconds (1 femtosecond is 10[sup]-15[/sup] seconds). This pulse was able to detect an escaping electron as soon as it was freed from the helium atom. Depending on the electromagnetic field of the laser pulse, the electron either accelerated or decelerated. … “We only need to know the time centre of the pulses very precisely, and our technique allows us to measure this to very high precision…An even shorter pulse would give better time resolution, but the resolution can far exceed the pulse duration. We can confirm this by doing statistics for a lot of measurements and calculate the statistical standard error of the mean, which in our case is 850 [zeptoseconds.](https://en.wikipedia.org/wiki/Orders_of_magnitude_(time)) That’s not alotta yattaseconds. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [November 19, 2016, 1:04pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/23 "2016-11-19T13:04:58Z")
Cool, thanks for the update! (And, the chance to read Pasta’s awesome 2013 post. But hey, give Chronos a break – at least he responded honestly.) A zeptosecond? Ha. Let’s see… “the time interval between Jimmy Page hearing a Delta Blues song, and his figuring out a way to rip it off without giving the composer any credit.” ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [November 19, 2016, 7:52pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/24 "2016-11-19T19:52:23Z")
Zeptosecond. The time between Zeppo trying to get a witty line off and the instant Groucho beats him to it. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [November 19, 2016, 8:17pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/25 "2016-11-19T20:17:10Z")
> [@Chronos](#): > > It won’t help. The time I mentioned is to one second as one second is to 10[sup]19[/sup] years. But now you need perspective on what 10[sup]19[/sup] years is. That’s about a billion times longer than the current age of the Universe … [snip] It’s not often we can describe the age of the universe as being brief … well done folks … ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [November 19, 2016, 8:20pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/26 "2016-11-19T20:20:40Z")
> [@Colibri](#): > > Here in Panama, we call that the “Panasecond.” It is theorized that, since cars sometimes start blowing their horns _even before the light has changed_, faster-than-light travel must be possible. That’s merely a common fallacy used to justify faster-than-light phenomena. Physicists now know that it’s the result of quantum entanglement between the facing traffic light and the one on the perpendicular street coupled with relativistic displacement of simultaneity in the traffic light control box. The hot-blooded Panamanian driver observes the perpendicular traffic light change, and starts blowing his horn _ **before** _ the facing light changes. This has the beneficial effect of eliminating any wasted time due to the latency of light or sound travel time. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 19, 2016, 9:31pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/27 "2016-11-19T21:31:30Z")
> [@Exapno\_Mapcase](#): > > Zeptosecond. The time between Zeppo trying to get a witty line off and the instant Groucho beats him to it. Darn fine username / post combo there Good Sir. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 19, 2016, 9:45pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/28 "2016-11-19T21:45:44Z")
> [@watchwolf49](#): > > It’s not often we can describe the age of the universe as being brief … well done folks … When I think of long periods, I think of the amount of time before all lumps of matter have (through cold fusion) [turn into iron-56](https://en.wikipedia.org/wiki/Future_of_an_expanding_universe#Matter_decays_into_iron): 10 to the 1500th years. (Assuming protons are stable.) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 19, 2016, 10:25pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/29 "2016-11-19T22:25:32Z")
Once you’re looking at that kind of numbers, there are a lot of other scenarios you have to rule out first, not just proton decay. Off the top of my head, I’d expect all matter to coalesce into black holes and then re-evaporate long before that happened. Heck, you could probably evaporate all of the black holes into neutrinos, re-coalesce the neutrinos into black holes, and re-evaporate them multiple times. ---
**Author:** ![Kedikat](https://avatars.discourse-cdn.com/v4/letter/k/ed655f/32.png) [@Kedikat](https://boards.straightdope.com/u/Kedikat)\ **Post date:** [November 20, 2016, 1:18am UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/30 "2016-11-20T01:18:32Z")
What would be the fastest event that can happen? It would have to happen over a very small distance. Can we measure that an electron moved from one “shell” to another in an atom? Is that the fastest event? From the time that whatever initiated it to move, to the time it completed the move. I realize that distance is a fuzzy concept in the subatomic realm. And the electron shell/orbit concept as well. But it is an event on a tiny scale. Is there a faster event? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 20, 2016, 1:14pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/31 "2016-11-20T13:14:49Z")
Quantum leaps are often regarded as instantaneous, but that’s a misunderstanding. The electron is never “in the space between” the two states, but the process still takes time, and is still limited by the speed of light. And the difference between the expected location for two different electron shells is far, far greater than some of the distances we’re talking about in this thread, and so the time is far, far longer. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [November 21, 2016, 3:33am UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/32 "2016-11-21T03:33:41Z")
> [@Kedikat](#): > > What would be the fastest event that can happen? It would have to happen over a very small distance. Can we measure that an electron moved from one “shell” to another in an atom? Is that the fastest event? From the time that whatever initiated it to move, to the time it completed the move. I realize that distance is a fuzzy concept in the subatomic realm. And the electron shell/orbit concept as well. But it is an event on a tiny scale. Is there a faster event? You don’t need physical motion to have an “event”. For example, you can create an unstable subatomic particle and then see how long it lives before it decays into something else. These are the shortest time intervals measured (if indirectly). There’s nothing in our current understanding of physics that prevents arbitrarily short intervals between related events (and certainly not between unrelated events). ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [November 29, 2016, 10:28pm UTC](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138/33 "2016-11-29T22:28:00Z")
20-min video, for high school physics: [**Physics: “Short Time Intervals” 1960 PSSC Physical Science Study Committee; MIT**](https://youtu.be/HQzBdDuFnWc) Very good, indeed. [Previous page](https://boards.straightdope.com/t/what-is-the-shortest-time-measurable/647138.md?page=1)