# speed of light **URL:** \ **Category:** Factual Questions\ **Created:** [February 28, 2001, 6:17pm UTC](https://boards.straightdope.com/t/speed-of-light/56251 "2001-02-28T18:17:08Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [February 28, 2001, 6:17pm UTC](https://boards.straightdope.com/t/speed-of-light/56251/1 "2001-02-28T18:17:08Z")
The speed of light (And all other streams of massles energy emission) propagates through a vacuum at 299,492,458 meters per second. Why does the universe choose this specific velocity? Why not a billion meters per second? Why not 55 MPH? enolancooper ---
**Author:** ![Podkayne](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Podkayne](https://boards.straightdope.com/u/Podkayne)\ **Post date:** [February 28, 2001, 6:26pm UTC](https://boards.straightdope.com/t/speed-of-light/56251/2 "2001-02-28T18:26:52Z")
The best answer so far is: no particular reason. There are several fundmental constants in the Universe, and they could conceivably have any value, though some values of some constants would lead to very short-lived Universes, or Universes where life wouldn’t be possible. We just lucked out–or looking at it from the other side of the coin, if our Universe wasn’t suitable for life, we wouldn’t be around to think about it anyway. ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [February 28, 2001, 10:18pm UTC](https://boards.straightdope.com/t/speed-of-light/56251/3 "2001-02-28T22:18:20Z")
> [@](#): > > \*Originally posted by enolancooper \* > **The speed of light (And all other streams of massles energy emission) propagates through a vacuum at 299,492,458 meters per second. Why does the universe choose this specific velocity? Why not a billion meters per second? Why not 55 MPH?** A slightly better answer is, the speed of light is [299, **7** 92,458 meters per second](http://www.xs4all.nl/~jcdverha/scijokes/11_4.html#6). And the speed of light can be derived (like Maxwell did) from other constants, but that just shifts the question to why are those constants the values that they are. ---
**Author:** ![erislover](https://avatars.discourse-cdn.com/v4/letter/e/71e660/32.png) [@erislover](https://boards.straightdope.com/u/erislover)\ **Post date:** [February 28, 2001, 11:00pm UTC](https://boards.straightdope.com/t/speed-of-light/56251/4 "2001-02-28T23:00:05Z")
Speed of light nuthin’, how the hell did Avogadro come up with that number? Sheesh. ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [February 28, 2001, 11:05pm UTC](https://boards.straightdope.com/t/speed-of-light/56251/5 "2001-02-28T23:05:09Z")
Thanks for catching that typo. Some people out there really are paying attention. enolancooper ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [March 1, 2001, 1:52am UTC](https://boards.straightdope.com/t/speed-of-light/56251/6 "2001-03-01T01:52:07Z")
eh. What’s another 300,000 meters per second? I’m sorry I can’t help you with your original question, though. I mean, _really_ sorry. ---
**Author:** ![JCL1013](https://avatars.discourse-cdn.com/v4/letter/j/b9e5f3/32.png) [@JCL1013](https://boards.straightdope.com/u/JCL1013)\ **Post date:** [March 1, 2001, 2:03am UTC](https://boards.straightdope.com/t/speed-of-light/56251/7 "2001-03-01T02:03:02Z")
> [@](#): > > \*Originally posted by aynrandlover \* > \*\*Speed of light nuthin’, how the hell did Avogadro come up with that number? Sheesh. \*\* I can’t tell you who did come up with it, but the chem teacher just said today in lecture that all Avogadro came up with was his law (the only famous thing anyhow). It’s only called his number because it follows from his law. ---
**Author:** ![AETBOND417](https://avatars.discourse-cdn.com/v4/letter/a/47e85d/32.png) [@AETBOND417](https://boards.straightdope.com/u/AETBOND417)\ **Post date:** [March 1, 2001, 2:58am UTC](https://boards.straightdope.com/t/speed-of-light/56251/8 "2001-03-01T02:58:12Z")
> [@](#): > > \*Originally posted by aynrandlover \* > \*\*Speed of light nuthin’, how the hell did Avogadro come up with that number? Sheesh. \*\* I know you’re just kidding, but having learned about this recently, I too have wondered this. WTF? What did he do to come to this figure? ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [March 1, 2001, 3:12am UTC](https://boards.straightdope.com/t/speed-of-light/56251/9 "2001-03-01T03:12:24Z")
Avogadro’s number is defined as the number of atoms in _exactly_ 12 grams of carbon-12. It provides a convenient way to convert between grams and atomic mass units. ---
**Author:** ![Mikahw](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Mikahw](https://boards.straightdope.com/u/Mikahw)\ **Post date:** [March 1, 2001, 5:59am UTC](https://boards.straightdope.com/t/speed-of-light/56251/10 "2001-03-01T05:59:24Z")
Yeah, Avagadro’s number. Always comes up in casual conversation. "Hey Bill, did you know that if there was exactly 18 grams of water in that glass, there would be 602,000,000,000,000,000,000,000 molecules of water in there? Yep, comes up all the time, I bet…