# What is time? **URL:** \ **Category:** Great Debates\ **Created:** [June 19, 2009, 8:10am UTC](https://boards.straightdope.com/t/what-is-time/500278 "2009-06-19T08:10:55Z")\ **Posts on this page:** 19\ **Page:** 2
**Author:** ![Bosstone](https://avatars.discourse-cdn.com/v4/letter/b/22d042/32.png) [@Bosstone](https://boards.straightdope.com/u/Bosstone)\ **Post date:** [June 19, 2009, 10:02pm UTC](https://boards.straightdope.com/t/what-is-time/500278/21 "2009-06-19T22:02:39Z")
Time is not important, only life. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [June 19, 2009, 10:41pm UTC](https://boards.straightdope.com/t/what-is-time/500278/22 "2009-06-19T22:41:22Z")
I’ve always thought of time as a measure of duration and/or change. Change happens, which is the physical justification for identifying time as “real”. If nothing ever changed, time could be said to not exist. Since things change, we need some way to measure the persistence of certain properties, like location, color, or whatever else may change. Hence time. ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [June 19, 2009, 11:08pm UTC](https://boards.straightdope.com/t/what-is-time/500278/23 "2009-06-19T23:08:46Z")
> [@Paleface](#): > > Time did not really slow down, the astronaut’s perception of time was altered due to the physical effects of velocity. This is incorrect. Time is not absolute. Time for one subject can be 1 year and 2 years for another subject. It is not perception, it is reality. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [June 19, 2009, 11:24pm UTC](https://boards.straightdope.com/t/what-is-time/500278/24 "2009-06-19T23:24:15Z")
Give me a minute and I’ll tell you. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [June 19, 2009, 11:51pm UTC](https://boards.straightdope.com/t/what-is-time/500278/25 "2009-06-19T23:51:55Z")
> [@Dervorin](#): > > How would you define rate without time? Well, you can’t. You can’t define it without distance either. That’s why they’re all tied together in the equation t = d/r. Recall that Einstein thought of time and space as a single property: spacetime. Therefore, you could not define distance either, without time — since distance implies space. And so time is simply a ratio of distance and rate. It cannot be removed from the other two, just as “m” cannot be removed from f = ma. It is also important to note that if rate is zero, then time is undefined. ---
**Author:** ![Zephyurs](https://avatars.discourse-cdn.com/v4/letter/z/dfb087/32.png) [@Zephyurs](https://boards.straightdope.com/u/Zephyurs)\ **Post date:** [June 20, 2009, 12:29am UTC](https://boards.straightdope.com/t/what-is-time/500278/26 "2009-06-20T00:29:20Z")
Time is the increase in available microstates. ---
**Author:** ![Yumblie](https://avatars.discourse-cdn.com/v4/letter/y/76d3ee/32.png) [@Yumblie](https://boards.straightdope.com/u/Yumblie)\ **Post date:** [June 20, 2009, 1:39am UTC](https://boards.straightdope.com/t/what-is-time/500278/27 "2009-06-20T01:39:19Z")
> [@Liberal](#): > > Well, you can’t. You can’t define it without distance either. That’s why they’re all tied together in the equation t = d/r. Recall that Einstein thought of time and space as a single property: spacetime. Therefore, you could not define distance either, without time — since distance implies space. > > And so time is simply a ratio of distance and rate. It cannot be removed from the other two, just as “m” cannot be removed from f = ma. It is also important to note that if rate is zero, then time is undefined. To expand on this, every object moves through spacetime at _c_, the speed of light. If you’re standing still, you’re not moving through space and moving through time at _c_. When you start moving faster through space, you lose some speed through time, which we see as time slowing down. A photon travels through space at _c_, so it has no velocity through time. ---
**Author:** ![Locrian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/locrian/32/14146_2.png) [@Locrian](https://boards.straightdope.com/u/Locrian)\ **Post date:** [June 20, 2009, 1:59am UTC](https://boards.straightdope.com/t/what-is-time/500278/28 "2009-06-20T01:59:11Z")
> [@Bosstone](#): > > Time is not important, only life. Exactly. If we were all immortal, would we even need time? Probably. We’d still need some type of measurement to express simple things like blinking to writing a dissertation. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [June 21, 2009, 12:14pm UTC](https://boards.straightdope.com/t/what-is-time/500278/29 "2009-06-21T12:14:13Z")
Time is the metric according to which causes are sorted before their effects. We can infer two physical agencies, causality and randomness, from their visible consequences. Causality (the agency supporting the cause-and-effect relationship) creates a limit in how rapidly causes may propagate over distances relative to matter, that limit being the speed c. Einsteinian relativity lays out a model for this propagation and its dependence on matter. We often refer to the speed as “the speed of light” but that is really only an artifact of its earliest recognition. Randomness is the agency supporting effects without causes, dictating the second law of thermodynamics and the metric we call “entropy”, and it also tends to sort states whose organization feels meaningful to us before states whose organization feels less so if those states shift randomly. The human perception of time is very evolved (in the Darwinian biological sense). It is a feeling of a stuff flowing by. The deepest meaning of this human perception is disappointing; it’s a naturally occuring metaphore in our brains, because brains manipulate cause and effect relationships and nothing more. Within a few orders magnitude range of time, distance, speed, mass, and so forth, and with just a couple orders of magnitude precision in measurement, our simple unenlightened and linear and uncoupled metaphore of time has let us and all our ancestors and relatives draw the next breath and grab fruit from trees just fine. At least, that’s my take. ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [June 21, 2009, 5:48pm UTC](https://boards.straightdope.com/t/what-is-time/500278/30 "2009-06-21T17:48:17Z")
Time is 18:48 ---
**Author:** ![Paleface](https://avatars.discourse-cdn.com/v4/letter/p/f19dbf/32.png) [@Paleface](https://boards.straightdope.com/u/Paleface)\ **Post date:** [June 22, 2009, 1:08pm UTC](https://boards.straightdope.com/t/what-is-time/500278/31 "2009-06-22T13:08:06Z")
> [@Boyo\_Jim](#): > > No, seconds are a manmade construct for measuring time, as inches are a manmade construct for measuring distance. No, seconds are manmade constructs for measuring minutes. Time measures events. No? Give an example of time that is not related to an event. ---
**Author:** ![Paleface](https://avatars.discourse-cdn.com/v4/letter/p/f19dbf/32.png) [@Paleface](https://boards.straightdope.com/u/Paleface)\ **Post date:** [June 22, 2009, 1:19pm UTC](https://boards.straightdope.com/t/what-is-time/500278/32 "2009-06-22T13:19:16Z")
> [@sailor](#): > > This is incorrect. Time is not absolute. Time for one subject can be 1 year and 2 years for another subject. It is not perception, it is reality. Einstein, in his theory of relativity, posited that all clocks, both mechanical and biological, slow down as they approach the speed of light. This tells me that the physiology of motion effects one’s perception of time. In the example I provided, the observer continuously observes the traveler. Time does not slow for the observer, only for the traveler. The only explaination for the phenomenon is that the motion/velocity effects the traveler’s perception of time. ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [June 22, 2009, 1:50pm UTC](https://boards.straightdope.com/t/what-is-time/500278/33 "2009-06-22T13:50:54Z")
The word is “affects”. And I guess this is a matter of interpretation. The point is that for both subjects their time is real. The clock has not “slowed down”; it has only slowed down for an outside observer in the same sense than when I go away from a building the building becomes smaller for me. ---
**Author:** ![Paleface](https://avatars.discourse-cdn.com/v4/letter/p/f19dbf/32.png) [@Paleface](https://boards.straightdope.com/u/Paleface)\ **Post date:** [June 23, 2009, 12:22pm UTC](https://boards.straightdope.com/t/what-is-time/500278/34 "2009-06-23T12:22:15Z")
> [@sailor](#): > > The word is “affects”. Thank you putting in the effort for the much needed correction. > [@](#): > > And I guess this is a matter of interpretation. “Perception” would be a more fitting word to use. > [@](#): > > The point is that for both subjects their time is real. The clock has not “slowed down”; it has only slowed down for an outside observer in the same sense than when I go away from a building the building becomes smaller for me. The building does not become smaller, you just perceive it to be smaller. As for traveling near lightspeed, clocks, both biological and mechanical, actually do slow down. But time, as a manmade construct, is constant. Clocks are measuring devices that work independent of time. ---
**Author:** ![MichaelQReilly](https://avatars.discourse-cdn.com/v4/letter/m/df705f/32.png) [@MichaelQReilly](https://boards.straightdope.com/u/MichaelQReilly)\ **Post date:** [June 23, 2009, 1:12pm UTC](https://boards.straightdope.com/t/what-is-time/500278/35 "2009-06-23T13:12:44Z")
> [@Lanzy](#): > > How could it be anything other than “made up”? Its certainly not a noun, I can’t go out and get a bucket of time. You can measure the passage of it but only by using units we also made up. Our measurement of it is based on real things, such as the rotation of our planet, but just like our base 10 numbering system, it didn’t have to be. If we didn’t hold it in such high regard, we would never be late for appointments. There are many people laying in graveyards (who I’m going to presume to speak for since they are dead) to whom time is a very real thing - seeing as its passage eventually caused their non-existence. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [June 23, 2009, 1:19pm UTC](https://boards.straightdope.com/t/what-is-time/500278/36 "2009-06-23T13:19:54Z")
“Time. Time. What is time? Swiss manufacture it. French hoard it. Italians squander it. Americans say it is money. Hindus say it does not exist. Do you know what I say? I say time is a crook.” -Peter Lorre in _Beat the Devil_ ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [June 23, 2009, 9:49pm UTC](https://boards.straightdope.com/t/what-is-time/500278/37 "2009-06-23T21:49:52Z")
> [@Paleface](#): > > No, seconds are manmade constructs for measuring minutes. Time measures events. No? Give an example of time that is not related to an event. Wow. Paleface, all but six of the posts that preceeded yours discuss time without it being related to an event, including an earlier post of yours, and most of them do so exclusively. Without regard to their individual merits, generally they all make real statements that must either be true or not, or ask questions that must have some kind of real answer. Even specific times can be unrelated to an event, for example Planck time, or ephemeral time. ---
**Author:** ![Notassmartasithought](https://avatars.discourse-cdn.com/v4/letter/n/c0e974/32.png) [@Notassmartasithought](https://boards.straightdope.com/u/Notassmartasithought)\ **Post date:** [June 24, 2009, 3:23am UTC](https://boards.straightdope.com/t/what-is-time/500278/38 "2009-06-24T03:23:11Z")
**Quartz** is right. [http://thinkexist.com/quotation/the\_only\_reason\_for\_time\_is\_so\_that\_everything/15594.html](http://thinkexist.com/quotation/the_only_reason_for_time_is_so_that_everything/15594.html) Einstein said, it must be true. ---
**Author:** ![Chief\_Pedant](https://avatars.discourse-cdn.com/v4/letter/c/a6a055/32.png) [@Chief\_Pedant](https://boards.straightdope.com/u/Chief_Pedant)\ **Post date:** [June 25, 2009, 12:13am UTC](https://boards.straightdope.com/t/what-is-time/500278/39 "2009-06-25T00:13:57Z")
Time is the the descriptor for the set of all distributions of mass-energy in space. We have good mathematical modeling for mass-energy but no idea at all what “space is.” A given distribution is a given “moment” of time. If the distribution changes to an alternate one, the description of both distributions is “time.” Until we understand what space is, we will not understand why time exists–i.e. why there is any but a single distribution of all that is. Because we model mass-energy as if it were “in” space, we tend to think of time as a separate “thing.” It’s my (personal, unupported, meaningless…) speculation that we will come to recognize mass-energy and space are variations of the same thing in the same way we came to realize how mass and energy and variations of the same thing. In that construct mass and energy don’t move in space–they are space, moving. Perhaps when we get to a decent Theory of Everything, we’ll understand time. Until we do, any description of time is going to seem very circular. [Previous page](https://boards.straightdope.com/t/what-is-time/500278.md?page=1)