Wikipedia:Reference desk/Archives/Science/2012 October 20

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

October 20

Tea bag infusion

If you place a tea bag in cold water, will it eventually produce the same concentration of tea as if you place it in boiling water ? If so, how long will it take ? If not, why not ? StuRat (talk) 02:52, 20 October 2012 (UTC)

I have read various sources that for various teas a certain temperature is necessary to release various essential oils. For example:http://empiretea.com/tea_facts.htm This would imply that cold water will not do the trick. That makes sense since you are not trying to dissolve just one pure crystal that is fully soluble at room temperature, but many different substances, some of which may not enter solution below a certain temperature.μηδείς (talk) 02:58, 20 October 2012 (UTC)

That's also why you would want to use hot, but not boiling water when steeping tea and coffee: many of the bitter or unappetizing flavors tend to dissolve at boiling temperature, plus boiling agitates the leaves and breaks them up. this site recommends anywhere from150 °F (66 °C) to 205 °F (96 °C) for the ideal steeping temperature depending on the type of tea. --Jayron32 04:46, 20 October 2012 (UTC)

Wouldn't the temperature be below that for sun tea (not to mention refrigerator tea) ? StuRat (talk) 05:33, 20 October 2012 (UTC)

Jayron, that well-known scientist Douglas Adams says precisely the opposite. He maintains the waterneeds to be boiling and not just hot. -- Jack of Oz ^[Talk] 05:49, 20 October 2012 (UTC)

The cold water infusion is not unusual in Japan. It takes 2 to 6 hours. See [1] and [2], the translation is terrible though. But I prefer to using boiling water. Oda Mari (talk) 08:29, 20 October 2012 (UTC)

DNA is being a little loose with his terminology. The water isn't actually boiling when you make the tea - it has stopped boiling a second or two beforehand. --Tango (talk) 15:31, 20 October 2012 (UTC)

That's not loose terminology. "Boiling water" is an accepted phrase for water at its boiling point, even if it is not currently simmering. The point is that you want the water still at its boiling point when it hits the tea. This is different from green teas and herbal teas, where you generally want the water to have cooled slightly to 95C. 212.183.128.23 (talk) 17:21, 20 October 2012 (UTC)

Eurgh, no. You can't get a decent cup of tea up a mountain because the water needs to be as close to 100C as possible. Herbal teas and coffee need to be brewed at more like 95C, for maximum tastiness, but British black tea needs boiling water. You then pour the 100C water on the tea in a warm vessel, and then it is brewed in about 2 minutes (varies by blend). Any longer, and it gets too tannic. Any lower, and it's weirdly weak because the most delicious compounds don't get released.

Wait, "boiling agitates the leaves"? We're not adding the leaves to water that's still being heated.86.159.77.170 (talk) 12:46, 20 October 2012 (UTC)

• I'd just like to comment that this is one of those questions where everybody has strong beliefs and nobody has any evidence to back them up.Looie496 (talk) 15:42, 20 October 2012 (UTC)

Sure we do. We know that British people trying to make cups of tea at high altitude get disappointing results unless they use special equipment. We know that the flavour profile of tea brewed at 95C is different from the flavour profile of tea brewed at 100C, and that this reflects a difference in the compounds in the tea. We know that different sorts of tea react differently to temperature and length of steeping: British black tea specifically requires boiling water, while green teas and herbal teas require water that has slightly cooled. "Required" here meaning "required in order to produce a product that people generally enjoy drinking". We know that allowing tea to stew (leaving it in the water for more than a few minutes) significantly increases the tannic content, making the tea bitter and astringent. We know that tea left in cool water for a long time produces a different flavour profile to tea to which boiling water has been added for a few minutes, because of aromatics and the different solubilities of different compounds.

Companies spend a lot of time and energy gathering exactly this evidence. Standards bodies spend a lot of time and energy gathering this evidence.

The only subjective bit is that some people prefer their tea bitter and astringent. And some people are probably thinking of how to brew one sort of tea, while others are thinking of how to brew another sort of tea. 212.183.128.23 (talk) 17:18, 20 October 2012 (UTC)

How do we know those things? Who did the studies? Where are the results published? Looie496 (talk) 19:44, 20 October 2012 (UTC)

And a key question we can determine once we see the published studies, are these based on decent research such as double blind studies (with the tea provided at same temperature for consumption) or crappy anecdotal evidence? I would also ask who's 'people'? The British people may be famous for their love of tea, but they're far from the only people who drink black tea. No evidence has been presented that the British flavour preference for black tea is universal despite the apparent assertation that British black tea requires boiling water. Nil Einne (talk) 22:30, 20 October 2012 (UTC)

OK here's some references for you. Here's one person with a scientific explanation for why ginger tea tastes better with boiling water. --TammyMoet (talk) 09:19, 21 October 2012 (UTC) We have a standard method on Wikipedia for brewing tea: ISO 3103. And if you follow the first link on that page you find that no less a body than the Royal Society of Chemistry have indeed addressed the topic. --TammyMoet(talk) 09:22, 21 October 2012 (UTC)

The second link doesn't seem much more useful then what's already discussed here. It just a news release and seems to be largely the opinion of one random person with no sources to back up the claims. Some of them could be sourced (e.g. multiple boiled water generally having a lower oxygen content although whether that will truly make a significant difference to brewing tea I don't know), others appear to be random personal opinions (and I'm not even considering the stuff like avoid vulgar slurping). E.g. I expect in a number of countries there would be no clear cut preference for fresh milk vs UHT milk or UHT milk will even be preferred in a double blind taste test, presuming people can even tell the difference. It wouldn't surprise me if you could even find a source to demonstrate this. Note that one key point I was getting at above which I'm obviously repeating here, just because some people prefer something in some way doesn't mean everyone does, tastes can vary quite significantly and it rarely makes much sense to say one taste is 'right'. So anything which claims something is better because it produces a better tasting product should also tell you better tasting to who. The ISO standard, as our article says, is not intended to suggest thats the best method for brewing tea (as of course with most standards). It's intended to provide a standard way of brewing tea so comparisons can be made. Nil Einne (talk) 14:38, 21 October 2012 (UTC)

Why wasn't The Endeavour airlifted to its museum instead?

I saw that taking the Endeavour shuttle through the surface streets of Los Angeles was an EPIC pain in the ass; trees were cut, traffic was disrupted and it was a delicate balancing-act of sorts to make sure no damage was made by and to the shuttle.

So I'm thinking: Instead of towing it at 2 MPH for an entire weekend from the airport to its museum, why didn't they hook maybe 12 cables to 12Chinook helicopters, and have them all airlift the shuttle to its destination in probably under one hour?

See how quick that would have been? No tree would had to have been chopped down, and no traffic disrupted, right?

So how many helicopters would it really have taken? (It was my estimate of 12, right?) And the best pilots in the world would've been hired for the job to synchronize this all as flawlessly as can be.

Or if a squadron of 12 helicopters would have been too difficult, how about an airship/blimp instead? How big would the blimp need to have been or how many would have been needed?

Thanks. --75.39.142.63 (talk) 05:30, 20 October 2012 (UTC)

Sounds very risky. StuRat (talk) 05:35, 20 October 2012 (UTC)

I had assumed the entire time that it was all a publicity stunt. I have also been told by people in the know that the FAA requires the evacuation of everything under the flight path a helicopter dragging something via tow cable, which would have also been a huge pain in the ass. Also, it would take 9Sikorsky S-64 Skycranes to lift the Endeavour, ignoring the weight of additional supporting cables and such. For the Chinook, 12 sounds right, assuming it can tow as much as it can carry on board. I also wonder, did Toyota do any lobbying or offer to pay for the pain-in-the-ass work in exchange for the honor of dragging it through LA? If someone was offering to foot the bill, that would certainly make the decision far easier.Someguy1221 (talk) 05:40, 20 October 2012 (UTC)

It would be risky. Looking at Space Shuttle, it seems they weigh 172,000 lbs empty. And a CH-47 Chinook can lift 28,000 lbs. Though that is likely the rating for lifting something straight up. Once you use seven Chinooks (by my calculations: 172,000/28,000 = 6 and change), you'd have to lift diagonally. And if I'm not mistaken, that would alter how much you can lift since you're not doing it straight up. Add to that, that you would have to fabricate some sort of rigging to be able to pick up the shuttle without any odd shearing forces etc. The wings and such aren't made to bend after all since they're covered in fragile tiles. So, assuming you do all of that... Now you have 7 helicopters lifting a gigantic plane through the air over the second most populous city in the country. If anything breaks or goes wrong, you don't have much of anywhere to set the thing down in a hurry, and you possibly have (2*3*7) 42 rotor blades winging their way very quickly off in any direction they feel like going. Dismas|^(talk) 05:48, 20 October 2012 (UTC)

I would question the feasibility of having that many helicopters working in tandem. Per a few sources [3] [4] [5], it sounds like attempts were made to use 2-4 helicopters to carry a load but these were fraught with problems. While it's true these attempts were targetted at testing the feasibility of using multiple lift in general, it sounds like there were problems even when excellent helicopter pilots were used. Using seven helicopters (probably more since 7 is prime number) combined with a load you do not want to damage combined with problems Dismas mentioned sounds risky even with the 'best pilots in the world'. Nil Einne(talk) 08:34, 20 October 2012 (UTC)

What's the payload of the biggest airship ever? — Grr, that article has a section titled Heavy lifting that says nothing quantitative.—Tamfang (talk) 06:22, 20 October 2012 (UTC)

Why not partially disassemble it into sections, which can be trasnported more easily? Plasmic Physics (talk) 09:21, 20 October 2012 (UTC)

I mean, it's not as if the thing is ever going to fly again. Plasmic Physics (talk) 09:23, 20 October 2012 (UTC)

Man, where's your sense of romance? People were thrilled to see that thing lumber by. And there was much rejoicing (and free publicity) in the land, amen. Clarityfiend (talk) 09:33, 20 October 2012 (UTC)

The report that I heard said that it could not have its wings removed and re-attached due to the tiles. The wings were never meant to be taken off once put on. Dismas|^(talk) 10:21, 20 October 2012 (UTC)

Cut them off. I'm not a very sentimental person, however, I am a rational person. Rationality tells me that it was a huge waste of money and effort to transport the thing the way it was. Plasmic Physics (talk) 10:58, 20 October 2012 (UTC)

That's not rational. The whole point of transporting it to the museum was to make the whole historic artifact available at the museum, for the public and I guess for future study. If you're going to demolish it and reassemble it into a facsimile of the original, why not just scrap the whole thing and build a fibreglass replica? Then you can reuse the valuable components. Cutting it into pieces and reassembling them into a shuttle-shaped object is sentimental: either transporting the whole thing or just scrapping it and making a fibreglass replica would be the 'rational' options.86.159.77.170 (talk) 12:39, 20 October 2012 (UTC)

Simple, because a fibreglass replica is not an historical artifact, and does not achieve a the objectives of the mission. Moreover, being reaasembled does not remove its status as authentic, it may lowers its resell value. Compare it with Abu Simbel temples. Plasmic Physics(talk) 13:13, 20 October 2012 (UTC)

I think to me it all depends on where the trees were. Wnt (talk) 19:20, 21 October 2012 (UTC)

A helicopter external load can only be suspended directly under the centre of lift - for conventional single rotor helicopters that is directly below the centre of the rotor. Lateral load vectors would simply flip the helicopter over once the resultant tilt angle exceeds the dynamic rollover limit. This makes lifting objects with more than one helicopter extremely difficult, if not simply impossible. Roger (talk) 10:49, 20 October 2012 (UTC)

A simple jig could solve the center of gravity issue, albeit with a weight penalty. Suppose you have 4 helicopters, imagine an H shaped jig with the load suspended from the center and each helicopter providing lift on each corner. This is never done (AFAIK) due to the control issues Nil Einne pointed out above. Aerobatics maneuvers are entertaining at airshows but performing them above urban airspace simply isn't worth the risk. A8875 (talk) 11:05, 20 October 2012 (UTC)

It would be an enormous weight penalty. The jig would have to be very large because there are limits to how close together helicopters can safely fly. Once you get that large, it would need to be very strong to take the weight without flexing too much and breaking. Strong means heavy. I wouldn't be surprised if it ended up being heavier than the shuttle. --Tango (talk) 15:49, 20 October 2012 (UTC)

Yep, I'm pretty sure I read that the trailer rig they used to tow the shuttle through LA weighed around 120,000 pounds, and it just had to get the weight from the shuttle to the wheels. To support it by helicopter, you would need huge centilevered beams with the ends spaced far enough apart for the individual helicopters. Even if the rig didn't weigh more than the tow setup they used, it would take five more helicopters just to lift the rig.209.131.76.183 (talk) 15:00, 22 October 2012 (UTC)

And as a practical matter, the time and cost for engineering studies, construction of the rig, safety measures and other factors would probably have ended up being greater than the ground transportation that was used

Animal Eating Record

So a friend and I are trying to figure out which animal eat the highest percentage of its own body weight per day. The Wiki article for Shrew claims that it is the culprit, but there is no citation. Any sources to out there to indicate that it is indeed the shrew, or perhaps a different animal altogether.199.94.68.91 (talk) 14:48, 20 October 2012 (UTC)

Hummingbirds need to eat more than their body weight a day. The "metabolism" section in that article suggests there are insects that eat even more.88.112.36.91 (talk) 15:35, 20 October 2012 (UTC)

Edit conflict - I'm apparently wrong, but I'll post it anyway since it the concepts are true even if the conclusions isn't! Thesquare-cube law means smaller animals generally need more food in relation to their weight than larger animals. Homeotherms (loosely speaking, warm-blooded animals) also tend to need more food. So, I would expect the record to be held by a small mammal, such as a shrew. I have no sources for precisely which small mammal is the winner, though. --Tango (talk) 15:41, 20 October 2012 (UTC)

Birds are also warm-blooded, and flying probably requires more intake than does walking around. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:32, 20 October 2012 (UTC)

Flying takes more energy per unit time, but walking takes more energy per distance traveled (citation needed). Also, shrews spend a lot of time digging, which is fairly energy intensive. SemanticMantis (talk) 16:45, 20 October 2012 (UTC)

• You're basically looking at a scaling law in regards to metabolism, so smaller animals will eat more than larger ones with a similar metabolism. The shrews and hummingbirds have been mentioned. Amoebas and the like will presumably ingest large meals in one sitting. For one-time meals in the verterbrates, I would bet on the gulper. μηδείς (talk)

The leech? HiLo48 (talk) 20:37, 20 October 2012 (UTC)

You might go far with organisms that deliberately consume more nutrition than they can use. Anopheles gambiae and a jumping spider that eats it gorge on food far beyond what their bodies can process, and actually wind up pooping out completely unprocessed food (specifically blood, in both cases).Someguy1221 (talk) 01:14, 21 October 2012 (UTC)

(citation needed)? My understanding is that, in the case of mosquitoes, the red liquid released during feeding is not unprocessed whole blood, but rather a primarily aqueous, cell-depleted fraction. The mosquito can collect more nutrients from a blood meal by disposing of this liquid fraction and retaining the protein-rich cells. There's no evolutionary advantage to a mosquito taking more blood than it can use—every extra second it spends with its proboscis in some mammal's hide is an extra second where it risks getting squished.TenOfAllTrades(talk) 23:07, 21 October 2012 (UTC)

Animals which need to grow very rapidly might top the list, like the caterpillar stage of moths and butterflies. StuRat (talk) 17:20, 21 October 2012 (UTC)

Intersex Individuals and the Medical Community

How does the medical community treat intersex individuals? Gender is so ingrained in our mindset that I consider it difficult to not think in terms of the gender binary. Also, there are biological aspects that define the two sexes. Even doctors and other medical professors put race (white, black, asian, mixed), gender (male or female), or age into consideration. They may not rely on those factors completely, but they still put them into consideration. A person who is not statistically likely to get a disease may have a chance to get a disease by some atypical route. How do doctors put intersex individuals into consideration? Do they check hormone levels or something to see whether or not the individual has more of the female sex hormone or male sex hormone in order to determine the sexual/gender tendency of the individual even though the actual sex/gender is not clear-cut?75.185.79.52 (talk) 19:13, 20 October 2012 (UTC)

I suspect that the effects of their medical condition (having been operated upon to change their gender, taking injections and pills, etc.) would swamp any differences in gender. So, they may do worse than either men or women. To look at a specific case, a man who becomes a woman, and has hormones to help him grow breasts, should probably have regular mammograms. (Even men can get breast cancer, although uncommon.) StuRat (talk) 17:25, 21 October 2012 (UTC)

I think the treatment by the medical community and the degree to which gender is ingrained probably vary rather dramatically from place to place. I'm not sure the "gender binary" is very ingrained here in Thailand for example, at least in the urban areas. I don't know how the medical community deal with it in practice here, and there is probably substantial variation within the medical community, but for interest, the last time I had to fill in a medical form it said "Gender (at birth)" rather than "Gender". Sean.hoyland - talk 15:10, 22 October 2012 (UTC)

What are the choices? Maybe masculine, feminine and neuter? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:22, 23 October 2012 (UTC)

The forms I've seen don't have choices, so you are free to put anything you want e.g. "Can't remember, I was a baby". Sean.hoyland - talk 12:13, 23 October 2012 (UTC)

Maybe they switched from "Sex" due to curb responses like, "Three times a week" and such. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:15, 23 October 2012 (UTC)

Mysterious insect invasion

Our home (exterior) has been visited by thousands of these winged insects that are primarily black with orange "pinstriping". They are approx. 20mm long at maturity, and apparently seeking out warmth, as autumn descends here in upstate NY. Thanks in advance for your help. PS: I have jpg photo, but haven't figured out how one pastes it here. --Paolo38 (talk) 21:18, 20 October 2012 (UTC)

Do they look like this? Deor (talk) 21:53, 20 October 2012 (UTC)

I've had maybe a dozen of those bugs in my house in the last few weeks. Apparently they come inside when it gets too cold outside. On the plus side, they are easy to catch. I tend to release them back outside. Unfortunately a couple managed to torch themselves on my halogen lamp, making a horrible stench. StuRat (talk) 17:13, 21 October 2012 (UTC)

Solar Flare, Time Capsule Computer

I'm thinking of writing a fanfiction, and I have some questions. I care a surprising amount about realism in a story that takes place in a world populated by talking magical ponies.

Could a single solar flare (or coronal mass ejection or whatever) destroy almost all of the technology on the far side of a planet without killing everypony on the close side? Also, what effect would it have on ponies with cybernetic implants? What if they're connected to the power grid at the time?

Also, my story involves having some kind of underground computer system that was successfully built to continue running for centuries after the end of civilization. This would involve it, being self-repairing, incredibly long-lasting, or some combination of the above. It also has one or more emulated pony running on it, so it doesn't doesn't have to be all that simple to repair. Technology is somewhat more advanced than we have now, but from what I understand, that would just make computers that much harder to repair. Magic exists in the setting, but I'd like a better explanation than "a unicorn did it". Is this at all feasible? If so, how large would it have to be? What kind of natural power source would last that long without changing and be underground? A geyser? Geothermal power? Nuclear power?

— DanielLC 23:20, 20 October 2012 (UTC)

If I (an Engineer) was requested to design & build an electric generator that would run unattended for centuries, I would go for nuclear isotope poweredthermionic conversion. Once can choose a suitable isotope with a half life of centuries, and use it to heat a metal cathode vacuum thermionic generator. There is literally nothing to fail, wear out, or chemically change in such a generator, apart from fission products (which are easily understood and contained). About the only failure mode is seal failure leading to loss of vacuum. However the electronics industry has about 100 years experince in making virtually failure proof glass to metal seals. Reliability is always dramatically improved by using multiple small generators rather than one large one. Energy conversion efficiency will be very low though - perhaps 1% or less. Ratbone121.215.41.218 (talk) 01:55, 21 October 2012 (UTC)

I'm struggling to see how realism is going to be compatible with talking magical ponies. This is a science reference desk. Only you can know with what defences and attributes your imaginary ponies will be endowed, but I think it will be safe to say they will struggle to overcome the threats you throw at them, but the hero/heroine will emerge victorious in the end.--Shantavira|^{feed me} 11:49, 21 October 2012 (UTC)

Sigh. I miss The Outer Limits. Wnt (talk) 15:47, 21 October 2012 (UTC)

You have realism through Magic A is Magic A andLike Reality Unless Noted. Since there are no unicorns in the computer system, they can't do magic, and it will work through the physics that rule real life. Magic might help for producing the stuff to begin with, but that's it. —DanielLC 20:01, 21 October 2012 (UTC)

• Of the power options you mention, I think geothermal power makes the most sense - provided you're not on a fault line, it shouldn't be broken, barring greenhouse disasters the difference in temperature won't go away, and a thermocouple, so far as I know, is something so basic, with no moving parts and which could be made to resist corrosion, that I am hard pressed to imagine any mode of failure. And as a bonus, you've already specified the power source be underground anyway. Wnt (talk) 15:51, 21 October 2012 (UTC)

• You might be interested in this actual project to build an underground clock meant to last 10,000 years: http://longnow.org/clock/. It relies on solar power and people to wind it up, which seems rather silly for a clock, but might work well for a computer, provided it only needs to run when people are there to wind it. Also, how nicely steampunk. StuRat (talk) 17:08, 21 October 2012 (UTC)

• It's designed to run without any external assistance, and emulating a pony is much, much more sophisticated than counting. — DanielLC20:01, 21 October 2012 (UTC)

• Not really. Clocks that showed leap year, days in each month, phases on the Moon, rising and setting of the Moon and Sun, and movements of constellations had high degrees of complexity to them. This could also be used to simulate the movements of a pony. Clockwork is clockwork.StuRat (talk) 22:35, 21 October 2012 (UTC)

• Mechanical systems are Turing complete. While you could, in principle, build a larger version of the 10,000 year clock that simulates a person's brain, it would have to be the size of a mountain and have a reaction time measured in hours. That would not work for the purposes of this story. —DanielLC 23:41, 21 October 2012 (UTC)