Wikipedia:Reference desk/Archives/Science/2012 October 25

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October 25

Can two swords really both cut the other?

I saw it in a movie once. Two swords hit hard and both appear to cut (or break) through the other. There's very little resistance, like they were pre-broken.. If anything breaks at all shouldn't one should have the upper hand? And another thing, can two swords identical enough for the ancients to accept for duelling purposes really cut each other? Sagittarian Milky Way (talk) 03:12, 25 October 2012 (UTC)

Not really cut, no. However, if they struck each other hard enough, both might shatter, and that could look the same, to the casual observer. StuRat (talk) 03:17, 25 October 2012 (UTC)

(edit conflict) I'm not sure where the line between "cut" and "break" would be, but I could imagine two swords could both cause the other to shatter or break, so that you'd end up with two broken blades. FWIW, in actual swordfighting in actual combat, there was very little sword-to-sword contact expected. In an actual melee, you didn't want to mess up the edge of your blade, and repeatedly striking it against another blade is a sure way to do that. This article here has a large section devoted to the myth of the sword-on-sword fight. It is technically a humor site (Cracked.com), but surprisingly in many articles like this, Cracked does a very good job of fact checking and providing references, as this article does. --Jayron32 03:19, 25 October 2012 (UTC)

Mythbusters tried and failed to break a sword with a sword, for whatever that's worth. —Tamfang (talk) 04:07, 25 October 2012 (UTC)

Yes, presumably because they didn't strike them together with sufficient force. Of course, it may well be impossible for two humans to do so. With the proper machinery, though, this would not be a problem. StuRat (talk) 04:30, 25 October 2012 (UTC)

Obviously you don't watch Mythbusters. When they couldn't do it themselves, per SOP, they built a machine to apply superhuman force. Correction: Grant(?) modified(?) an existing machine to apply first human force, then when that didn't do the job, cranked it up and still didn't get the hoped-for results. Clarityfiend (talk) 06:45, 25 October 2012 (UTC)

I didn't see that episode, but have seen others. They regular conclude that, because they can't do something, that it can't be done. There must be some amount of force which would shatter both swords. It doesn't surprise me if they weren't able to produce that force, however. StuRat (talk) 08:45, 25 October 2012 (UTC)

Generally for myths like that they build a rig that outperforms the best/strongest humans, and if that can't do it they claim that no human can do it. Sometimes they ramp it up afterwards, like when they used a giant pendulum (I think designed for simulating car crashes) to attempt to knock a dummy out of his socks. 209.131.76.183 (talk) 11:34, 25 October 2012 (UTC)

All of you seem to be misremembering the episode. They were testing whether a sword could cut a machine gun barrel, not whether it could cut another sword. It makes sense that a machine gun barrel would be significantly harder to cut; after all, it has to withstand hundreds of explosions every second and not break, whereas a sword's most important quality is to be sharp. The answer to the OP's question, if breaking counts as cutting, is almost certainly "yes"--swords suffer from metal fatigue over time, cracks appear, and those cracks only grow larger as the swords get used. Add to that the fact that swords made in pre-modern times could be of low quality, because metalworking wasn't as developed as it is today, and I'd be surprised if two swords didn't simultaneously break during some battle in the history of warfare. --140.180.252.244 (talk) 21:42, 25 October 2012 (UTC)

Nay, tis thee who art confuseth.[1] You're thinking of a different episode. Clarityfiend (talk) 01:45, 26 October 2012 (UTC)

I agree that Mythbusters (at least the junior team) too often say "We couldn't do it in the first way we thought of, therefore it can't be done" (when I readily see another possible approach), but for sword hitting sword what's the other way they could try? —Tamfang (talk) 20:39, 29 October 2012 (UTC)

In addition to a bigger, badder machine that can strike the swords together faster, another approach would be to dip them in liquid nitrogen, as low temperature collisions often mirror high speed collisions. That is, things which behave in an elastic manner normally will behave in an inelastic manner under either low temps or high speeds. StuRat (talk) 02:25, 1 November 2012 (UTC)

Anecdata: I was once in a theatrical production in which metal prop swords were used. In stage-fighting, there is vastly more blade-to-blade contact than in realty. In this case, the swords would occasionally simultaneously cut into one another when clashed together; the metal was soft enough that a pair of interlocking notches formed, which brought the fight to an abrupt end. AlexTiefling (talk) 07:31, 25 October 2012 (UTC)

Bear in mind that in the pre-industrial era, steel production and sword smithing was more of an art than a science, especially at the cheap end of the market or in cultures that had a poor grasp of the techniques required. Some examples from our Iron Age sword article; "Polybius reports that the Gauls at the Battle of Telamon (224 BC) had inferior iron swords which bent at the first stroke and had to be straightened with the foot against the ground." The Icelandic Eyrbyggja saga describes a similar problem: "whenever he struck a shield, his ornamented sword would bend, and he had to put his foot on it to straighten it out". A search for "broken sword blade" on Google only brings up pages of results relating to fantasy fiction and role-play games. However, Scottish Culture and Traditions By Norman C Milne says "Towards the end of the 17th century (in Scotland), we start to see broken sword blades utilised as dirk blades. This may be due to numerous factors. (John) Wallace has suggested that the local blade smiths could not manufacture blades to the same quality and temper of imported blades that were forged at Solingen and Passau." (p.99) Broken swords cannot have been unkown in England, since they appear in several coat of arms. An example is the Cartwrights of Nottinhamshire, whose arms included a crest depicting; "a wolf's head, erased or, pierced through the neck with a sword blade argent, broken off at the hilt".[2] Alansplodge (talk) 17:12, 25 October 2012 (UTC)

Another reference for sub-standard blades "Sometimes, in spite of their rigorous training, smiths were simply not "sufficyantlith ylernyd", as the Bristol masters complained in 1403. Furbours (arms smiths) in 1350 were engaged in the dangerous practice of mending broken sword-blades, instead of completely reworking them." English Medieval Industries: Craftsmen, Techniques, Products By John Blair (p.185). Alansplodge (talk) 17:34, 25 October 2012 (UTC)

If I were making a stage-fighting sword, I'd use a soft, ductile steel -- something that wouldn't hold an edge, and which would bend rather than fracture when overstressed. --Carnildo (talk) 02:05, 30 October 2012 (UTC)

AC adapter output power

I've taken the liberty of moving this to Wikipedia:Reference desk/Computing#AC adapter output power (Moved from Science Refdesk). You should get better answers, and besides, those guys have to have something to answer. :) Wnt (talk) 18:43, 25 October 2012 (UTC)

Suicide torpedoes and the Cuban missile crisis

The Mark 45 torpedo was a US, nuclear, wire-guided torpedo which apparently would destroy both ships when fired. My questions:

1) What was the intended use of such a weapon ?

2) I understand from the Secrets of the Dead Cuban missile crisis episode, that the Soviet Union had a similar nuclear torpedo called "the special weapon". Was this also a suicide weapon ? Do we have an article on it ?

3) I'm a bit skeptical of that episode, as they confused an isotherm with a thermocline. They also said that the missiles in Cuba reached the capability to destroy Los Angeles, prior to the Crisis. Is that true ? StuRat (talk) 18:45, 25 October 2012 (UTC)

For 3) It's about 2,300 miles from western Cuba to Los Angeles (per Google Earth's measurement tool). Operation Anadyr deployed both R-12 and R-14 ballistic missiles. The R-12 Dvina missiles which were already present in Cuba prior to the peak of the crisis have a range of about 1,300 miles. The R-14 Chusovaya missiles, which were on the cusp of deployment during the crisis itself had a range of about 2,300 miles. Russian Space web suggests the R-14s themselves were never delivered, but Astronautix article suggests maybe some were (with more on the blockaded ships). There's no indication that R-14's ever became active in Cuba; the Russian Space Web article says only half the R-12s were fuelled. -- Finlay McWalterჷTalk 19:27, 25 October 2012 (UTC)

Six to eight of the R-12s were armed and could have been used if necessary. Those could have struck as far north as Washington, DC or Dallas, with 1.3 megaton warheads. There were many more nukes on Cuba than that, though — there were lots of tactical nuclear weapons that would have been used in case of an American invasion, or an attack on Guantanamo. There were well over 100 nuclear warheads on Cuba at the time of the crisis. But they did not have the capability of destroying Los Angeles; the R-14s were not at all ready, even if some of the components had arrived. Lots of details. --Mr.98 (talk) 12:39, 27 October 2012 (UTC)

Just as an aside, early submarines were essentially all "suicide weapons"; successful deployment of a charge on one often meant nearly certain death for the crew. The H. L. Hunley (submarine) had a Spar torpedo as its primary weapon. If it worked as designed, the spar would break off upon ramming and leave the torpedo inside the target boat, but I'm not sure it ever worked that well, and the boat itself was a leaky mess. You had to either have balls of brass or a brain of oatmeal to serve on a ship like that. --Jayron32 19:30, 25 October 2012 (UTC)

For 1), the claim is almost certainly bullshit; probably a garbled misrendering of some combination of historical bravado (back in my day, men were real men, with torpedoes that blew up everything) and real concerns about the possible misfortune associated with careless use of the early Mark 45. (The first generation Mark 45 – unlike the Mod 1 and Mod 2 revisions that followed – had no set minimum enabling range; they were 'live' as soon as they were fired, and a premature triggering of a nuclear-tipped torpedo was...bad...out to a much greater distance than it would be a for a conventional fish. The Mod 1 and 2 versions had a minimum enabling range of 2050 yards to prevent this sort of...incident.) Norman Friedman's U.S. Submarines Since 1945: An Illustrated Design History cover this point. A passing Straight Dope comment [3] also calls attention to the outcome of the Baker test of Operation Crossroads, which detonated a 23 kiloton warhead (twice the yield of the warhead on the Mark 45) amidst an array of ships and submarines; no submarines further than 1000 yards from the detonation were sunk. TenOfAllTrades(talk) 20:03, 25 October 2012 (UTC)

(ec) For 1), the Mk-45 carried an 11Kt W34 warhead; that's about 2/3 the yield of the Little Boy used at Hiroshima. The Mark 45 torpedo article says it was for anti-submarine warfare, with a range of up to 8 miles. The Crossroads BAKER shot, a comparable explosion depth but with about double the energy, sank the submerged USS Apogon (SS-308) at 850 yards but not USS Dentuda (SS-335) at about 1,500 yards (Dentuda returned to service after the explosion). We can see that an explosion with double the W34's energy didn't sink a submarine less than 1 mile from it; we can handwave the W34's kill radius for submerged vessels at maybe half a mile or less (a number very dependent on circumstances, as Underwater explosion shows the complexities depending on conditions). So there's no indication that a Mk-45 was an automatic suicide weapon, although obviously it's something more difficult to use effectively than an ordinary torpedo. -- Finlay McWalterჷTalk 20:11, 25 October 2012 (UTC)

And this report on Apogon's wreck says she wasn't broken or holed, but that she sank from leaking. Obviously Apogon wasn't crewed during Crossroads BAKER; we can't be sure that had she been, her crew couldn't have ameliorated the damage, pumped out the flooding spaces, and saved the boat. So that suggests the effective kill radius of the explosion was even less. -- Finlay McWalterჷTalk 20:32, 25 October 2012 (UTC)

Now for 2), the supposed Soviet suicide torpedo. The relevant submarine was Soviet submarine B-59 - that article says it too had an 11 kiloton warhead, but this article from the National Security Archive says it was 15 kilotons. That article quotes the boat's political officer and later her captain declaiming that they'd they'd use the torpedo and die. But it's not clear that they meant the torpedo itself would kill them, or just that using the torpedo would escalate what they thought was a conventional depth-charging into a nuclear one. In any event, emotions were obviously running high, so that isn't very reliable evidence of actual weapon performance. We don't know the range of the Soviet torpedo; it's fair to assume it was much the same as the American one, but who knows. This article says that (by 1970 at least) there were two designs of tactical nuclear torpedo used in the Soviet Navy, one for anti-submarine and the other for attacking aircraft carriers (or, presumably, other large surface targets of high value). -- Finlay McWalterჷTalk 22:37, 25 October 2012 (UTC)

Thanks so far. That episode also implied that the entire American fleet could be sunk with one such torpedo, but this sounds like an absurd claim, based on the above figures. Also, let my add one more Q:

4) Are any such nuclear anti-naval weapons still used by modern submarines or surface ships ? StuRat (talk) 03:56, 26 October 2012 (UTC)

Russian submarines still carry the VA-111 Shkval and Type 65 torpedo, which are both capable of being fitted with a nuclear warhead. There are no submarine-submarine weapons still in use in the US Navy that carries a nuke, as least as far as Wikipedia articles believe. The Tomahawk missile could be fitted with a nuclear warhead, but that variant was never deployed a warship, and was removed from service at the end of the Cold War. Someguy1221 (talk) 05:46, 26 October 2012 (UTC)

Eating peels

Is there a good scientific reason why we don't generally eat orange, or really any citrus, peels? Dismas|^(talk) 21:46, 25 October 2012 (UTC)

We don't have enough zest in our lives? Clarityfiend (talk) 22:17, 25 October 2012 (UTC)

(edit conflict) Depends on the part of the peel. The zest (colored part on the outside) is very tasty, contains a lot of essential oils from the fruit, and is a frequent ingredient in cooking. On the other hand, the "pith" (the white part of the peel between the zest and the edible part of the fruit) is generally very bitter and unappetizing, which is why it isn't often used in foods, though it can be in some applications. Preserved lemon is a common ingredient in a LOT of cuisines, and it contains both the zest and the pith. The pickling medium tends to mellow the bitterness of the pith, so you end up with a fully edible peel. --Jayron32 22:18, 25 October 2012 (UTC)

I don't find the white part of an orange peel bitter at all. It's almost flavorless. I occasionally munch on it as "something to do"; as far as I know it's pretty much a no-op, no calories, no nutrients, no harmful substances that I know of. (Grapefruit peel is another story.) --Trovatore (talk) 22:39, 25 October 2012 (UTC)

The albedo (the white spongy stuff) is the major industrial source of pectin (source: Harold McGee On food and cooking). It is about 1/3 pectin and 1/3 cellulose - the remaining third is oils and sugars (source: The Grapefruit: Its Composition, Physiology, and Products, Walton B. Sinclair). -- Finlay McWalterჷTalk 22:46, 25 October 2012 (UTC)

Good grief, an editor on this page that provides a useful relevant answer and includes a ref. I tips me lid. Greglocock (talk) 22:54, 25 October 2012 (UTC)

The reason, incidentally, that other fruits like apples aren't used so much for pectin production (even though they contain more than oranges) is that the pectin is physically mixed in with the tasty carbohydrate fleshy/juicy bits that people like to eat. In citrus fruit there's lot of pectin in that unwanted pith, so harvesting it doesn't mean they have to sacrifice more valuable fruity stuff. (ref:Sinclair) Sinclair also says that Sunkist is the largest producer of citrus pectin, but that there is more available than there is a market for it. I've found several papers where food scientists experiment with using processed (to remove flavoursome oils) albedo as a filler for ground meat dishes like burgers[4] and Turkish sausages [5]. The burger guy says they were nicer with the albedo; the sujuk chap isn't as clear about whether it improves the character of those delicious fermented horsemeat sausages. Mmmm. -- Finlay McWalterჷTalk 23:18, 25 October 2012 (UTC)

Also note that the peels may contain higher levels of pesticide residue. StuRat (talk) 03:49, 26 October 2012 (UTC)

Only if it is not organically grown.

An unrelated question: why does the edit toolbar not load? Plasmic Physics (talk) 08:28, 26 October 2012 (UTC)

Organic does not equal pesticide free. In common definitions of organic farming, the pesticides just need to be "organic" themselves - toxins that can be found in nature. It is also not immediately certain that such toxins are better for human health than synthetic ones, and there are reasons why the reverse may well be true (if health problems are discovered in an "organic" insecticide, it can't be modified to make it safer, because then it wouldn't be "organic" any more. Can't change it to require smaller dosages, can't change it to target insects only, can't change it to become inert in a day, can't change it to wash off easier. Whatever toxin a bacterium or a poisonous plant produces, that's what you get on your organic fruit. Peel it!) 88.112.36.91 (talk) 18:02, 26 October 2012 (UTC)

I eat orange peel every day; it's the best part of the marmalade.--Shantavira|^{feed me} 11:21, 26 October 2012 (UTC)

Not sure about the "we" in "we don't generally eat". Dried tangerine peel is popular in China. It's yummy too. Search for 陈皮 in google images. Sean.hoyland - talk 17:51, 26 October 2012 (UTC)

• I eat lime peel frequently. It's quite good. Looie496 (talk) 17:02, 27 October 2012 (UTC)

Me too, in miang kham. Delicious. Sean.hoyland - talk 17:55, 27 October 2012 (UTC)

"Kumquats are often eaten raw. As the rind is sweet and the juicy center is sour, the raw fruit is usually consumed either whole—to savor the contrast—or only the rind is eaten." Gzuckier (talk) 01:42, 29 October 2012 (UTC)