# Great science facts **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 1, 2013, 11:50pm UTC](https://boards.straightdope.com/t/great-science-facts/657272 "2013-05-01T23:50:55Z")\ **Posts on this page:** 20\ **Page:** 5
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [May 3, 2013, 2:37pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/81 "2013-05-03T14:37:10Z")
> [@Crafter\_Man](#): > > Let’s say you have 1 meter of \*stranded \*12 gauge wire and 1 meter of \*solid \*12 gauge wire. Since both are 12 gauge, both wires have the exact same cross-sectional area (3.31 mm[sup]2[/sup]). > > […]the 1 meter of stranded wire is really longer than 1 meter. The real length is probably around 1.03 meters or so. This is because the strands in stranded wire are twisted. The strands are in contact with one another, so don’t they therefore act, electrically, like a single wire of 1 m? The description above would be clearly true if each strand were insulated, but otherwise won’t current tend to take the path of least resistance, a straight line, rather than following the twist of each strand for a length of 1.03 m? ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 3, 2013, 2:43pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/82 "2013-05-03T14:43:45Z")
> [@CookingWithGas](#): > > The strands are in contact with one another, so don’t they therefore act, electrically, like a single wire of 1 m? The description above would be clearly true if each strand were insulated, but otherwise won’t current tend to take the path of least resistance, a straight line, rather than following the twist of each strand for a length of 1.03 m? The area of contact between each strand is pretty small (and therefore the contact resistance is pretty high), so you won’t see a lot of current jumping from one strand to the next. If you want to minimize/eliminate that contact resistance, you’d need the largest possible contact area, which means eliminating the air gaps between the strands - at which point you’ve arrived at the competing solid-wire configuration. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [May 3, 2013, 3:53pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/83 "2013-05-03T15:53:30Z")
> [@Crafter\_Man](#): > > No. The stranded wire will have slightly higher resistance. I think the skin effect [Skin effect - Wikipedia](http://en.wikipedia.org/wiki/Skin_effect) will have a greater effect on the resistance. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [May 3, 2013, 4:00pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/84 "2013-05-03T16:00:24Z")
Skin effect is negligible at frequencies below several hundred kHz, and all but nonexistent below 100kHz… all audiophile raving to the contrary. Most high-power circuits where wiring resistance would matter operate at very low frequencies, if not zero (DC). ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [May 3, 2013, 4:14pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/85 "2013-05-03T16:14:32Z")
A basic electricity fact that most people don’t know- The plus and minus symbols on batteries are wrong. For a long time, nobody was sure which way electricity flowed in a circuit. So, a scientist set up a device where a spark jumped from one side to the other. He observed until he was sure which direction the spark traveled. He got it wrong. But, it was a few centuries before anybody figured that out. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [May 3, 2013, 4:22pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/86 "2013-05-03T16:22:21Z")
> [@DocCathode](#): > > Oxygen combines with iron to form rust. Oxygen combines with aluminum to form sapphire. Huh. I’m not sure if I knew that rubies and sapphire were made of Aluminum oxide. (And it looks like not all aluminum oxide is sapphire; it has to form in the right crystal structure.) The detail I like is this: Iron oxide rust is reddish and brittle, with a tendency to crumble off the iron item and reveal fresh iron to be attacked by oxygen. Aluminum oxide that forms on an aluminum object will generally be the same color as aluminum, tougher and stronger than the pure metal. So it protects the item from further oxidation 🙂 ---
**Author:** ![terentii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terentii/32/212_2.png) [@terentii](https://boards.straightdope.com/u/terentii)\ **Post date:** [May 3, 2013, 4:32pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/87 "2013-05-03T16:32:33Z")
> [@Floater](#): > > St Petersburg has not been a capital since 1918, though. However, if you want capitals you can replace it with Tallinn. Russians have always referred to it as “the Northern Capital,” regardless of Moscow’s status. ---
**Author:** ![terentii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terentii/32/212_2.png) [@terentii](https://boards.straightdope.com/u/terentii)\ **Post date:** [May 3, 2013, 4:34pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/88 "2013-05-03T16:34:53Z")
> [@Colophon](#): > > 😕 > You mean the little gap where there’s no visible steam? Doesn’t that exactly prove what **Machine Elf** said? > > If you can see the “steam”, then you’re seeing tiny droplets of condensing liquid water. Water vapour is invisible. You might be able to see a kind of “shimmering” in the air, but that’s just because of the heat changing the refractive index of the air, same as a heat haze. Like other things in nature, you can “see” it (perhaps “observe” would be a better word) by the effect it has on its immediate environment. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [May 3, 2013, 4:40pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/89 "2013-05-03T16:40:56Z")
> [@BrotherCadfael](#): > > Well? Now I - even I - would celebrate In rhymes unapt the great Immortal Syracusan rivaled nevermore Who in his wondrous lore Passed on before Gave men his guidance how to circles mensurate. 3.141592653589793238462643383279 ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [May 3, 2013, 4:42pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/90 "2013-05-03T16:42:38Z")
> [@CookingWithGas](#): > > True. My monitor generated the light to show this post 1.5 x 10[sup]-9[/sup] seconds before I read it. Seriously, is it too much to ask that people be completely up to date on a thread before they respond to it? 🙂 ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [May 3, 2013, 4:56pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/91 "2013-05-03T16:56:48Z")
The tongue of the giraffe is prehensile. The pig has a corkscrew penis (The Master covered this). The male platypus has venomous spurs in his hind legs. The female platypus does not express milk through nipples. She sweats it out through her pores. The male seahorse carries fertilized eggs in a pouch. ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [May 3, 2013, 5:04pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/92 "2013-05-03T17:04:17Z")
Unoxygenated spider blood is clear. Oxygenated spider blood is translucent blue. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [May 3, 2013, 5:25pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/93 "2013-05-03T17:25:01Z")
> [@terentii](#): > > If you travel due east from New York City, the first European capital you come to is Madrid. Lisbon? Unless being like 1 degree of latitude off doesn’t qualify as “due east”. Not sure why this is supposed to be an interest/great science fact either, doesn’t seem surprising, except for the Lisbon thing. My own contribution: the only time elements heavier than iron are created are during the last moment of a star’s death. So all of the heavy elements in the world, including the ones in your body, are the result of a dying star. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 3, 2013, 5:30pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/94 "2013-05-03T17:30:31Z")
> [@CookingWithGas](#): > > The strands are in contact with one another, so don’t they therefore act, electrically, like a single wire of 1 m? The description above would be clearly true if each strand were insulated, but otherwise won’t current tend to take the path of least resistance, a straight line, rather than following the twist of each strand for a length of 1.03 m? No, that’s not what I am talking about. [Look at this pic](http://forums.autodesk.com/autodesk/attachments/autodesk/78/277099/1/Twisted%20Conductors.jpg). Notice how there is an overall corkscrew (helix) to the wire? That is because someone twisted the wire. As they were twisting the wire, a slight overal helix started to form and the wire got “shorter” at the same time, i.e. the distance between each end of the wire decreased. The wire “contracted” in a sense. But it didn’t \*really \*get shorter from an \*electrical \*standpoint; the actually path length remained unchanged. So if I have 1 meter of stranded wire, as measured with a simple tape measure, I am simply measuring the distance between the two ends. But because there is a slight overall helix to the wire (which is so subtle that it is difficult for your eyes to see), the actual, electrical length of the wire is slightly more than 1 meter. Even at DC. This is something very few electrical engineers know. ---
**Author:** ![Peremensoe](https://avatars.discourse-cdn.com/v4/letter/p/ce7236/32.png) [@Peremensoe](https://boards.straightdope.com/u/Peremensoe)\ **Post date:** [May 3, 2013, 5:36pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/95 "2013-05-03T17:36:49Z")
… ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 3, 2013, 5:41pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/96 "2013-05-03T17:41:19Z")
> [@Peremensoe](#): > > But that suggests that the current paths are following each individual strand. Why would they do that, given that they’re all touching? Why wouldn’t it just be the shortest conductive route? No I am not assuming current follows along each strand, because that does not happen, obviously. The strands are not isolated from each other. Read my post above over and over, and keep looking at the linked pic. You will eventually understand the effect I am talking about. And don’t feel bad if you don’t understand it right away. It also took me a long time to understand the effect. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 3, 2013, 5:47pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/97 "2013-05-03T17:47:08Z")
> [@terentii](#): > > Like other things in nature, you can “see” it (perhaps “observe” would be a better word) by the effect it has on its immediate environment. :rolleyes: Then I can see/observe gaseous oxygen and nitrogen by the effect they have on trees, flags, grass, and other objects that get jostled around by the wind. In fact, I can see/observe water vapor in the same way, since it’s already in the atmosphere as humidity. I hereby dismiss your “great science fact” as nothing more than semantic subterfuge. ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [May 3, 2013, 6:17pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/98 "2013-05-03T18:17:26Z")
> [@Machine\_Elf](#): > > semantic subterfuge. Band name! ---
**Author:** ![Furious\_Marmot](https://avatars.discourse-cdn.com/v4/letter/f/dfb087/32.png) [@Furious\_Marmot](https://boards.straightdope.com/u/Furious_Marmot)\ **Post date:** [May 3, 2013, 6:56pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/99 "2013-05-03T18:56:53Z")
Sloths nearly always climb down to the base of a tree in order to eliminate. There is no obvious reason why they do it this way. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [May 3, 2013, 7:03pm UTC](https://boards.straightdope.com/t/great-science-facts/657272/100 "2013-05-03T19:03:10Z")
> [@Furious\_Marmot](#): > > Sloths nearly always climb down to the base of a tree in order to eliminate. There is no obvious reason why they do it this way. My understanding is that sloths, or at least some species, hold it until it rains, and then let go - possibly to disguise their presence. I read an article years ago about a couple who had one as a pet? rescue? research animal? and had to spray a hose over it a couple of times a day so it would poop. [Previous page](https://boards.straightdope.com/t/great-science-facts/657272.md?page=4) [Next page](https://boards.straightdope.com/t/great-science-facts/657272.md?page=6)