Wikipedia:Reference desk/Archives/Science/2011 August 24

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August 24

Dark side of a planet

Is it possible for a planet to be habitable all the way around when it is locked into an orbit where only one side ever faces its star? And by habitable, I mean that the extremes aren't any more extreme than what is present on the Earth now. Dismas|^(talk) 04:37, 24 August 2011 (UTC)

If it had an extremely thick atmosphere, as in a gas giant, then the heat from the sunlight could be effectively redistributed to the other side. However, this would mean you couldn't see the Sun from the surface and you'd have thousand mile per hour constant hurricanes, like the Great Red Spot, and the atmosphere would be largely hydrogen, helium, and methane. So, this doesn't sound very habitable to humans, but I can imagine something evolving there which thrives in such conditions. StuRat (talk) 04:46, 24 August 2011 (UTC)

The tidally-locked world is a staple of science fiction. The earliest account I can find (with some admittedly very brief searches) is in Olaf Stapledon's 1937 novel Star Maker, which describes a tidally-locked world in orbit about a red dwarf star; the habitable region is limited to region along the terminator. (More often than not, science fiction treatments generally assume a civilization occupying the terminator, along the boundary between the day and night side of the planet.) In reality, under conditions of planetary mass and atmospheric density like Earth's, tidal locking leads to runaway glaciation (as water precipitates and freezes on the dark side), followed by atmospheric collapse (as atmospheric gases eventually condense on the cold side). In principle, one could stabilize such a system at least temporarily (on geological time scales) through extensive vulcanism (replenishing atmospheric greenhouse gases).

On the other hand, this paper discusses simulations of Gliese 581 d: a real exoplanet orbiting a real red dwarf star. The paper's simulations suggest that there could be liquid water (indeed, the planet could be ocean-covered) if it had a dense atmosphere (at least 10 times Earth's atmospheric pressure at the surface) rich in carbon dioxide and water vapor. Their simulations of a fully-locked, water-covered world with a 20-bar carbon dioxide atmosphere predicted temperatures as low as 280 K (a cool day, but above freezing) in the middle of night side, and a high of 305-310 K (a heat wave in most of the Western world) in the middle of day side. Whether you would consider that 'habitable' depends on your definitions. TenOfAllTrades(talk) 05:05, 24 August 2011 (UTC)

Wouldn't a pressure of 20 bar crush you like a bug? 67.169.177.176 (talk) 05:57, 24 August 2011 (UTC)

That pressure is like being under 200 m of water. Sure it would be bad for unprotected humans (cause we aren't designed for it), but fish have evolved to be happy at that pressure and much higher pressures. Life is certainly possible at such pressures. Dragons flight (talk) 06:36, 24 August 2011 (UTC)

Once the pressure equalizes, you wouldn't feel it. For example, if the same pressure air is inside your lungs as outside, you wouldn't feel any pressure on your chest. However, the behavior of gases changes a bit under higher pressures, so that a normal oxygen-nitrogen atmosphere doesn't work. Specifically, the nitrogen must be replaced by other gases. StuRat (talk) 08:42, 24 August 2011 (UTC)

And more importantly, the oxygen percentage must be reduced. -- 110.49.235.213 (talk) 13:58, 24 August 2011 (UTC)

You would also have to be careful of the CO2 you mentioned because CO2 is toxic at around 5% at atmospheric pressure, so you couldn't have more then 0.25% CO2 in the atmosphere of a 20bar planet unless that is something humans could adapt to. Googlemeister (talk) 14:47, 24 August 2011 (UTC)

Okay, I guess I should have been more precise. I wasn't referring to fish. I meant habitable by humans. Present day humans. So, judging by the answers thus far, I guess the answer is "no". Thanks, --Dismas|^(talk) 09:03, 24 August 2011 (UTC)

You can use Mercury as an example. It rotates about 1.5 times for every Mercury year (88 days). So, it gets about 1.5 days per year. It isn't locked, but it is very close to being so. On the light side, the temperatures are over 400°C. The dark side is below -180°C. The big problem isn't really the temperatures - it is the wind. Mercury has no noticeable wind because there is no noticeable atmosphere. But, if it were habitable, there would be monstrous storms due to the constant conflict between the two temperature extremes. -- kainaw™ 12:58, 24 August 2011 (UTC)

But, of course, then the temperatures wouldn't be so extreme, since the atmosphere would redistribute the heat. StuRat (talk) 21:15, 24 August 2011 (UTC)

Maybe not 500K extreme, but still pretty extreme. Googlemeister (talk) 13:11, 25 August 2011 (UTC)

Carrot overdose

What level of carrot consumption would lead to hypervitaminosis A ? According to that article, "Betacarotene, a precursor of vitamin A, is selectively converted into retinoids, so it does not cause toxicity." So, does that mean that carrots don't cause toxicity, or are there other forms of carotene or vitamin A present in carrots which do cause toxicity ? (Note that this question isn't about carotenosis, another problem from excess carrot consumption, leading to orange skin.) StuRat (talk) 05:06, 24 August 2011 (UTC)

Carrots contain beta- and alfa-carotene, neither of which can cause hypervitaminosis A. Only retinol can cause this type of overdose. 67.169.177.176 (talk) 05:51, 24 August 2011 (UTC)

Carrots can cause liver damage (cirhosis) etc. according to [1]. The term is apparently "carotenosis". Collect (talk) 13:12, 24 August 2011 (UTC)

I'm suspicious about carrots causing cirrhosis. [2] suggests such a thing, with help from alcohol, but I'm still not convinced. A rabbit caught hypervitaminosis A from eating too many carrots (PMID 11702930), but this is because they convert beta-carotene into retinol, which carrots do not possess. Excessive use of vitamin A supplements has caused liver cirrhosis requiring transplant [3] but their contents were unspecified in the publication. People who have turned yellow from eating too many carrots carotenosis had slightly elevated vitamin A levels but were otherwise healthy. (PMID 8449701). Apparently carrot overconsumption is not so uncommon (PMID 1764358) and was even claimed by a few patients to be addictive like tobacco! (PMID 1511232). Wnt (talk) 17:46, 24 August 2011 (UTC)

Carotenosis is NOT the same as cirrhosis! What happens in carotenosis is that the excess carotene deposits in your skin and turns it orange -- it DOES NOT CAUSE LIVER DAMAGE OR ANY SERIOUS HEALTH EFFECTS! And FYI, vitamin A supplements all contain retinol rather than beta-carotene. 67.169.177.176 (talk) 00:24, 25 August 2011 (UTC)

Agreed - I wasn't suggesting otherwise. Wnt (talk) 00:50, 25 August 2011 (UTC)

Our Beta-carotene#Side effects and briefly Vitamin A#Toxicity notes possible side effects from chronic excessive consumption of beta-carotene. It's not clear to me that this is likely to be a concern from consumption of carrots. Nil Einne (talk) 12:01, 25 August 2011 (UTC)

Only in people who smoke. 67.169.177.176 (talk) 05:59, 26 August 2011 (UTC)

Um read the articles? The biggest concern may be for smokers but there may also be a risk of competing with other vitamins for storage. There may also be a risk for drinkers as Wnt mentioned Nil Einne (talk) 18:24, 28 August 2011 (UTC)

Um read the articles yourself? The article Vitamin A#Toxicity refers to the effects of retinol, not beta-carotene, and therefore is irrelevant to this discussion (carrots contain beta-carotene but no retinol). And the "risk of competing with other vitamins for storage" that you mention, according to Beta-carotene#Side effects, only occurs with extremely high doses of beta-carotene that are unlikely to come from carrot consumption alone (according to the article, it's only a concern for people who take vitamin supplements while at the same time consuming a diet rich in beta-carotene). 67.169.177.176 (talk) 01:54, 29 August 2011 (UTC)

Hand propping

At what point does an aero-engine become too powerful to allow starting by hand? More specifically, is it possible to start an engine in the 500-to-600-hp range by hand-propping? I know that it is possible to swing the prop by hand with a 500-hp engine (most notably on the Winnie Mae), but what about even bigger engines? Is it possible, for example, to hand-prop an Electra 10-E (550-hp engines)? How about a DC-3 (as much as 1200 hp)? Or does it become too hard to pull the prop through with such high engine power (and/or too dangerous when the engine does catch)? What's the most powerful engine that has ever been hand-propped? 67.169.177.176 (talk) 06:14, 24 August 2011 (UTC)

I suppose you could hand-start much larger engines, provided the energy was stored up and then all used at once in the starter. Early phonographs worked in this way, by winding a spring prior to playing the record, as do hand-wound watches. An alternative to winding up a spring would be charging a capacitor. The first generation of telephones worked like this, and some military walkie-talkies. An external "starting unit" could be used to contain either the spring or capacitor, so this doesn't add to the weight of the plane. However, I'm not sure why this would be better than using an electric on-board starter. StuRat (talk) 08:17, 24 August 2011 (UTC)

No, I meant actually pulling the prop through by hand, either with just your hands or with some kind of device to give you a mechanical advantage (like a rope). Yes, some early aircraft used to have inertia starters which used a hand-powered flywheel to store the energy and release it at once, but that's not what I meant. Just FYI, the scenario I envision is a failure of the electric starter and/or the main battery. 67.169.177.176 (talk) 00:15, 25 August 2011 (UTC)

I see what you mean. I've often thought the same thing about cars. Yes, you can push-start a manual transmission car, but with an automatic, you're out of luck. StuRat (talk) 00:19, 25 August 2011 (UTC)

It isn't reasonable to talk about "such high engine power" because when the engine is being started it isn't producing any power. The significant parameter is the compression ratio. Hand starting quickly became impractical with larger and faster aircraft because of their higher compression ratios, higher displacement (eg cubic inches) and greater height above the ground. It was quickly recognized that hand starting an aero engine is a hazardous activity!

Major improvements in storage batteries helped hasten the end of hand starting. Between hand starting and modern electro-mechanical-pneumatic starters there was a "mechanical hand starter" called the Hucks starter. Dolphin (t) 08:32, 24 August 2011 (UTC)

So is it only the compression ratio that determines how much physical effort you have to make to pull the prop through, or does displacement also play a role? (Seems to me that both of these would be equally important.) Also, what is the practical limiting factor to hand-propping -- is it only the effort required, or is it the danger of getting chopped up when the engine catches? 67.169.177.176 (talk) 00:28, 25 August 2011 (UTC)

Costly military technologies

Many military technologies are beneficial to the civilian world -- at least according to those big military companies. Radar, jet engines, nuclear energy, composite materials, they all have great use in the peaceful world.

Now how does stealth technologies find their ways to benefit civilian lives?

Certainly there are short paths and long paths to civilian use. May be the way they build stealth fighters may be used to cut costs or increase reliability in civilian factories. But that's quite a long way to go from military to civilian and also marginal.

I mean how do we use radar-absorption materials or radar-reflection configurations technologies to make money in the civilian world? -- Toytoy (talk) 07:00, 24 August 2011 (UTC)

1) Radar-reflecting materials, if they can be adapted to work at other wavelengths, might be helpful on tall buildings which otherwise would tend to block cell phone transmissions, etc.

2) Similarly, such material might have application in space, to protect astronauts and equipment from various wavelengths of radiation.

3) If this technology is applied to microwave frequencies, it might be useful with microwave ovens.

4) Reflective materials might also have applications in reflector antennae.

5) People who are sensitive to EMFs (or think that they are) might appreciate a way to block such fields. StuRat (talk) 08:22, 24 August 2011 (UTC)

The stealth fighter uses its own geometric shape to reflect radar waves. It then uses some highly classified materials to absorb remaining EMF. The outer coating shall only absorb EMF at a number of limited frequency ranges.

Reflection of microwave is ancient technology. It has been available since the Iron Age. Though cooking-grade microwave may take a few more years to develop. In the mean time, we have forgotten most of the knowledge about fine cooking.

The only legitimate radar-absorbing material in my microwave oven shall be the CHICKEN!!!. I don't want to see my microwave oven heated to smoking by itself while my chicken remains frozen, just because someone used a radar-absorbing material inside the oven. -- Toytoy (talk) 10:44, 24 August 2011 (UTC)

You want the sides of the microwave oven to reflect microwaves, and perhaps the plate underneath the food should absorb them to cook from underneath. This is important if you want to simulate grilled food, for example. StuRat (talk) 06:33, 25 August 2011 (UTC)

A few days ago, I have seen a short article somewhere that argues that the U.S.S.R. failed because they could not use military technologies to improve their living while the U.S. usually have good civilian use for their military technologies. As a result, the U.S. could earn back a part of its military spending.

Now the stealth technology as a whole is extremely costly and it has to be highly classified. Even the allies can hardly know anything about it not to mention using it for any civilian product (if it can be used by the people). Does it mean that the investment to create this technology can be difficult to recover even in the distant future? -- Toytoy (talk) 10:52, 24 August 2011 (UTC)

Arguably and allegedly it might be recovered by providing military superiority in a conflict, with all the advantages which may follow from such superiority. Allegedly. --Ouro (blah blah) 12:10, 24 August 2011 (UTC)

How about cop defeating sportscars? Granted, just paying for your speeding tickets would probably be cheaper then a stealth car. Googlemeister (talk) 14:41, 24 August 2011 (UTC)

There is zero reason to believe that every military technology necessarily leads to useful civilian technologies, or that any spinoff technologies will actually be comparable in terms of their return on the investment. Even the most positive source of military R&D doesn't believe it is a substitute for civilian R&D, or that the economic returns are anything related. One should not confuse the two. It's true that military R&D can have, and has had, some civilian return. But expecting military R&D dollars to universally translate directly into civilian outputs is foolish and false economics.

This is a separate issue, mind you, from the possibility of boosting contractors who in turn use some of that boost to fund loss leaders and speculative R&D in other sectors, or manage to take the expertise in one field and apply it to others (military funding of transistor research, for example, didn't necessarily lead to lots of direct civilian applications, but it did increase the transistor industry's abilities and capital, which could then allow them to pursue other projects on the side). --Mr.98 (talk) 15:35, 24 August 2011 (UTC)

I think it has become more and more difficult for the top end military R&D to find its way into the civilian world. As a result, you spend more and more money to develop a weapon for making a weapon's sake. It is now less and less likely that the military R&D would help the civilian world and generate future tax money.

The stealth technology can be neutralized if some vital secrets are disclosed. Back to 1 million BC, an ape man who invented to use rocks would have become the king of the world if other ape men only fight with their bare hands. Now if a second ape man learned to use rocks, it did not make the first ape man's rock useless. Rocks are always fatal. The second ape man's rock only makes the first ape man more difficult to conquer the world.

However, if you have knowledge about any country's stealth fighter, you can probably invent a way to defeat it. Plus you can build one for yourself if you are capable. As a result, much of the technologies cannot be disclosed even to an ally. And on the other hand, the U.S., fearing that allies' stealth technologies can be uncontrollable, used its own power to get most of the allies to get on the F-35 wagon.

I think this is unlike before. The spread of jet engine technologies did not make existing jet fighters useless. -- Toytoy (talk) 16:53, 24 August 2011 (UTC)

I can't believe that nobody thus far has even mentioned the numerous ancilliary technologies required to make a successful stealth fighter, many of which have important civilian applications. Like for instance the new structural materials (composites, super alloys, etc.) from which the stealth fighter is made, which can also be used both in the civil aircraft market (lighter, faster passenger jets) and in other civil applications. Or the advanced forming/fabrication technologies used to give the airframe components their complex shape, which are also useful for manufacturing a wide variety of other products. Or the advances in engine technology which allow the same aircraft to supercruise at Mach 1+ without the use of gas-guzzling afterburners and also to take off and land vertically, and which might well be used in a future supersonic VTOL passenger jet. Or the top-of-the-line electronics used in the plane's fly-by-wire system, which could soon make their way into the next generation of PCs and Macs. It takes a lot more R&D to build a stealth fighter than just the radar-defeating technology, you know! 67.169.177.176 (talk) 03:07, 25 August 2011 (UTC)

Harrier Jumpjets with VTOL capabilities existed before the earliest functional stealth aircraft and the Concorde had supercruise ability well before any stealth aircraft as well. Googlemeister (talk) 13:09, 25 August 2011 (UTC)

True, but the Harrier couldn't break Mach 1 OR carry passengers, and the Concorde needed a three-mile runway to take off and land. With the new generation of engines developed in connection with the F-22 and F-35 programs, a future "super-Concorde" might be able to supercruise at Mach 2+ AND take off from any small-town airfield, AND burn less fuel per payload carried than either the Harrier or the Concorde. And besides, what about the advanced materials developed for the stealth program, not to mention the processing tachniques developed for those materials? These are also important technological advances with civilian applications. Same thing with the onboard electronics. 67.169.177.176 (talk) 06:09, 26 August 2011 (UTC)

Classification of TNOs: SDO vs. Detached TNO

CalRis (talk) 07:38, 24 August 2011 (UTC): Hello, I'm not sure whether this is the right place to ask this questions. I'm wondering about the orbital classification of Eris as a SDO-object (and the general classification scheme adopted by Wikipedia for TNOs). I am aware that the MPC lists it as an SDO. I'm only an astronomy aficionado, but the MPC's classification seems not entirely reliable. For example, according to the minor planet center, Sedna has the orbit type "Centaur", which is of course absurd (according to JPL's Small-Body Database Browser perihelion is 76 AU, aphelion is 995 AU). If you look at its "Centaur" list and briefly check its orbital elements (q, Q, a), you will find that there are other objects the classification of which seems rather doubtful (far too large q).

Anyway, which classification system/nomenclature is used by Wikipedia? Even the orbit classification of Eris in various scientific papers is varying (SDO, detached). Gladman et al. published (as part of the TNO-Bible The Solar System Beyond Neptune) a Nomenclature in the Outer Solar System which restricted SDOs to those objects which are currently scattering actively off Neptune (as indicated by 10 million years numerical integrations). They list both Eris and Sedna as detached TNOs.

The final verdict about what TNO-classification/nomenclature is going to be adopted by the scientific community is still out. So shouldn't Wikipedia be a bit more circumspect? One might include, for example, a respective hint by including a statement in the Eris-article that Eris is variously listed as an SDO and a detached TNO, according to the classification scheme used. What do you think? Salvete! CalRis

Wikipedia uses whatever scheme(s) are supported by "WP:reliable sources". We don't form general policies about whose ideas to prefer over the others, if both are out there in the available literature. It sounds like you know quite a bit about this topic, and you're welcome to edit these articles. By all means, please add the best sources you know about. (but do mind WP:V/WP:OR - we want data published elsewhere, not arguments that you come up with on your own, even if they're right). Wnt (talk) 02:06, 26 August 2011 (UTC)

Moon

1. Is there any difference between tempreture of the surface with underground of Moon?
2. Is there any Volcano on Moon?
3. What kind of Gases are find on Moon?
4. Is it applicable if you install a refinery in Space Rocket and inject the needed returning fuel of Orbiter by one of gases , in which are fine on Moon? Then, you need to deliver only the launching fuel in the orbiter and the weight of Space Rocket would be lighter.
5. Is it applicable to attach the fuel tank with Electrical Magnet to Space Rocket? And with turning off electricity, empty tank detaches the Orbiter.
6. Is it applicable if you launch Space Rocket only with sufficient fuel to reach the space. After a while send another fuel tank to space. n the returning way, at a meeting point, the Orbiter attaches itself to the fuel and returns home.
7. To manufacture Space Rocket lighter ,is it applicable if you fix Talc or Isinglass for the widows of Orbiter instead of Glassware?
8. Is it applicable if you withdraw making buildings in the surface of Moon?
9. Instead build the main part of the city in closed circle underground tunnels with adequate Oxygen and immune against storms and space stones?
10. Since the ground of the Moon is precious and it took years Human reached there, did you predict making cemetery on Moon? Or just organize sorrow ceremonies for the passed away people and let them be thrown to the orbit?
11. What are the seasons on Moon?
12. What are filled into the tiers of Moon Walkers?
13. Since Moon has lesser gravitational pull than earth, what technique did you applied that the Moon walker move without being thrown up?
14. In the first decades of Human permanent residing on Moon, they don't need cars. I gone suggest that you build a few parking lots on Moon , then install Cable Cars for getting to parking areas. Residents, would be transferred to miles by Cable car and they choose their way to minor districts they wish. — Preceding unsigned comment added by 2.144.220.32 (talk) 10:51, 24 August 2011 (UTC)

formatting fixed CS Miller (talk) 11:57, 24 August 2011 (UTC)

Were these questions meant for us humans of 2011? There are some answers in our article Moon, as for the volcanism and seasons and such, but with regard to the first decades of permanent human residence on the Moon - you'll have to wait a while, we don't have an answer to that one yet. --Ouro (blah blah) 12:07, 24 August 2011 (UTC)

1. Yes
2. No
3. See Atmosphere of the Moon
4. No
5. Yes
6. Yes
7. Can't help.
8. Don't understand.
9. Don't understand.
10. Can't help.
11. See Moon#Physical characteristics#Seasons
12. See Lunar Roving Vehicle#Features and specifications#Wheels and power
13. None required.
14. Can't help.

Plasmic Physics (talk) 14:12, 24 August 2011 (UTC)

Is that a homework question?Quest09 (talk) 14:39, 24 August 2011 (UTC)

I'd say yes to question 4. There has been work on extracting oxygen and hydrogen from the surface of the moon, which could be used to power a rocket[4]. More hypothetically, Helium-3 extracted from the moon could be used to power a nuclear fusion propulsion unit[5].

"What are filled into the tiers of Moon Walkers?" I assume you mean tires. The lunar rovers used by the Apollo missions had wire mesh tires, which contained no gases but were open to the vacuum.[6] --Colapeninsula (talk) 15:15, 24 August 2011 (UTC)

2) There may be long extinct volcanoes on the Moon. StuRat (talk) 20:37, 24 August 2011 (UTC)

5) When using an electro-magnet, you'd need to be careful to avoid damaging sensitive equipment with the magnetic field, or possible distorting readings. StuRat (talk) 20:57, 24 August 2011 (UTC)

6) It might be better the send up the fuel tank first, so the main launch can be aborted if the fuel tank doesn't make it. StuRat (talk) 20:44, 24 August 2011 (UTC)

7) Why not eliminate all windows and use cameras instead ? Yes, a power failure would mean they'd be blind, but they would likely be dead soon, in any case. StuRat (talk) 20:44, 24 August 2011 (UTC)

8 and 9 seem to suggest building underground instead of on the surface of the Moon. This is a good idea for the reasons you listed, and also because the ground would provide some protection from the radiation (which is provided by the thicker atmosphere on Earth) and temperature extremes. Also, underground construction on Earth is limited due to problems with ventilation, water infiltration, and the weight of the Earth to be supported. These problems either don't apply or are lessened on the Moon. However, Moonquakes do occur, due largely to tidal forces from the Earth, thus any structures would need to be able to withstand those, so don't use materials like unreinforced concrete. StuRat (talk) 20:23, 24 August 2011 (UTC)

10) Burying dead lunar colonists would work well, as they would become mummies and wouldn't require embalming to prevent the spread of disease. Launching them into space would be more problematic, as it would require a great deal of energy to launch their bodies into the Sun, and any other location would leave the body as space debris which would pose a hazard to future space exploration. StuRat (talk) 20:48, 24 August 2011 (UTC)

13) To clarify, the added weight of space suits keeps people from bouncing too high, when walking. However, the force upon landing is still the same, whether on Earth or the Moon, so it's not really an issue. Astronauts can walk the same as on Earth, by taking slower steps, but it isn't normally necessary. Hopping tends to be more efficient there. StuRat (talk) 20:35, 24 August 2011 (UTC)

14) Cable cars only work for short distances. For longer distances you need taller towers, or a series of towers. Lunar dust might also be rather abrasive on moving parts. StuRat (talk) 20:53, 24 August 2011 (UTC)

@7) Neither isinglass nor talc would have the strength to withstand the pressure differential between the space rocket fighter's cockpit and the vacuum of space, not to mention the thermal stress encountered during reentry -- or damage from enemy weapons! Indeed, not even ordinary glass can provide sufficient damage resistance for combat operations. Other, better materials like polycarbonate would have to be used for the fighter's windows. 67.169.177.176 (talk) 00:39, 25 August 2011 (UTC)

Just out of curiosity: Is this for some kind of futuristic sci-fi novel that you're working on? 67.169.177.176 (talk) 00:42, 25 August 2011 (UTC)

Oops -- I just noticed that I misread your question; you asked for suggestions to make a space rocket lighter in weight, while I thought you were trying to design a space rocket fighter like the ones in Star Wars. So in this case, combat operations are obviously not relevant. Still, I stand by the assertion that neither talc nor isinglass meet the structural or thermal requirements for a space rocket's windows (not the "widows" you mentioned in the original question -- the phrase "widows of Orbiter" refers to the spouses of crewmembers of the Challenger and the Columbia, and might even be considered offensive toward said spouses). Mica might do from a structural point of view, but it's also heavier than glass and less transparent, as well as hard to make into large panes. Polycarbonate, either alone or in some combination with pyrex glass, is prob'ly the best material for lightweight space rocket widows (I mean, windows...) 67.169.177.176 (talk) 03:47, 25 August 2011 (UTC)

Space tourism

The WP article on Space Tourism lists 7 Space tourists. Were not Malaysian Shiekh Shokor and South Korean lady astronaut Il So Yoen also Space tourists? Plus, I think that Simonyi went up twice. Am I not correct? Thanks. John: [e-mail address removed for personal sanity] — Preceding unsigned comment added by 220.137.67.189 (talk) 12:04, 24 August 2011 (UTC)

Dear John, I've removed your e-mail address, as these pages are frequented heavily by bots and the like, which might harvest your address and include it in some spam mail lists or whatever. Expect any and all answers right here. --Ouro (blah blah) 12:08, 24 August 2011 (UTC)

Sheikh Muszaphar Shukor isn't classed as a space tourist because he went up as part of a deal between Russia and the Malaysian government, rather than paying personally, and he performed scientific research while he was there. Russia, and the USSR, have a long history of repaying allies by sending people from their nations up into space.

Yi So-Yeon was chosen by the Korean astronaut program to fly in Soyuz, has a doctorate in biotechnology and is a legitimate astronaut. I don't know why you would question her status. --Colapeninsula (talk) 15:22, 24 August 2011 (UTC)

Not Russian? Not American? So, you must be a tourist if you go to space. 88.9.108.128 (talk) 21:06, 24 August 2011 (UTC)

I think Yang Liwei and a number of participants of the Chinese space program make that questionable no matter how strict you are. Nil Einne (talk) 11:43, 25 August 2011 (UTC)

You may be interested in Talk:Sheikh Muszaphar Shukor#re: Link to Space Tourism, Talk:Space tourism and Talk:Spaceflight participant. NASA and sometimes possibly the RKA did use the term Spaceflight participant (which is the same one they use to refer to people listed as space tourists) to refer Sheikh Muszaphar Shukor and Yi So-Yeon. I believe both trained as whatevernauts but didn't have many or any? official crew responsibilities on their respective missions (but did undertake research), and were considered whatevernauts by their countries and Russia at least on occasion. Note that it's been questioned why other then Christa McAuliffe, other people in the past both on NASA (including it sounds like Barbara Morgan) and the earlier RKA and Soviet missions have not been similarly deemed spaceflight participants (instead mission specialists or payload specialist) despite seemingly greater similarity of circumstances. In any case, neither seem to fit with the definition given in space tourism. Nil Einne (talk) 10:18, 25 August 2011 (UTC)

Flying submarine

So I was looking at Flying submarine and I was wondering if it's possible to have a dual purpose jet engine that can work both in water and in the air? ScienceApe (talk) 13:10, 24 August 2011 (UTC)

Seems unlikely. Jet engines typically rely on compression to operate, and while air is highly compressible, water is not. — Lomn 13:55, 24 August 2011 (UTC)

Water is also not very supportive of combustion compared to air. Googlemeister (talk) 14:38, 24 August 2011 (UTC)

On the other hand nuclear aircraft have been proposed.--Colapeninsula (talk) 16:03, 24 August 2011 (UTC)

And have some severe issues. The two major ones off the top of my head is that both coolant and shielding is heavy, and aircraft need to be light. The other issue is that you will have a lot of potential issues with containment in the event of a crash. Googlemeister (talk) 18:42, 24 August 2011 (UTC)

Nuclear aircraft have been built, they just haven't been flown under nuclear power. The Convair X-6 was a bomber that carried an operating nuclear reactor and all relevant shielding; the project was abandoned because it became unnecessary, not because it wouldn't have worked. Project Pluto, a nuclear cruise missile/unmanned bomber, was deliberately unshielded to increase its effects as a weapon; it was abandoned for political reasons. --Carnildo (talk) 02:16, 25 August 2011 (UTC)

(unindent) IMO, the most fundamental problem with the idea of a flying submarine (or underwater aircraft) is the contradiction in structural requirements, even more than the choice of propulsion. An aircraft must have a very lightweight structure in order to get off the ground, which would severely limit its submergence depth; a submarine, on the other hand, needs a very strong (and therefore heavy) pressure hull in order to withstand the water pressure, and so would not make a good aircraft. In other words, trying to build a flying submarine inherently requires designing it to meet two opposing requirements, which in practice always means that it will not perform either task well. 67.169.177.176 (talk) 03:19, 25 August 2011 (UTC)

I'm surprised the flying submarine page doesn't include Supercar (TV series). ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:04, 25 August 2011 (UTC)

Fly me to the moon ............. and then?

In the highly realistic movie 2001: A Space Odyssey, Dr. Floyd took a space ship to the moon and then from the moon base, he took another moon surface ship to the monolith.

Since there is practically no air on the moon, you can't use a winged aircraft on the moon. You have to provide all the lift by yourself.

It looks like that the surface ship would use much fuel and oxidant to fly on the moon surface for every second of flying. A hovercraft or a ground effect vehicle may be a good idea. However, in the vacuum, the gas cushion would be gone in a matter of seconds.

I think there's a new sci-fi movie about Hitler's moon base (when the Nazi was defeated, they went to the moon ...). I saw a Nazi-style sidecar motorcycle running on a moon highway in their Youtube trailer. Sorry I can't remember the movie's name. Is it a good idea to build a road on the moon surface for cars and bikes (assume that they have fuel and oxidant)? Since the moon can only provide 1/6 of earth gravity, friction force on the road surface can be a big problem.

The Apollo moon car was useful because it was better then walking or hopping. How do we travel on the moon? I mean travel in an efficient and practical manner. -- Toytoy (talk) 14:41, 24 August 2011 (UTC)

Once on the moon, a "hopping craft" would be a reasonable mode of travel (in fact, it has already been designed by multiple groups). You can have a craft hop great distances without requiring much energy to do so. The problem is that there is very little atmosphere for steering. So, you would want to hop short distances, correct the trajectory, and hop again. Because of the low gravity, it wouldn't feel like hopping does on Earth. Instead, it would feel driving down a road that goes up a bit and down a bit in a cyclic manner. As for driving on a road - the road itself would be a bad idea unless you are in the pothole repair business. The Moon doesn't have the atmosphere to block micro-meteors. They would likely tear up the roads faster than you could build them. The only safe place to consider roads would be as close to the side of the moon facing Earth as possible since there is far less meteor activity there. -- kainaw™ 15:03, 24 August 2011 (UTC)

I suspect you're seriously overestimating the 'impact' of micrometeors. Yes, the Moon's surface is covered with impact craters, but it's worth remembering that it took billions of years to get that way. (It's not as though the International Space Station is getting a fist-sized hole in it every day.) And millimeter-to-centimeter sized craters aren't really going to affect the function or performance of a road by much. Plus, lunar roads aren't going to be affected at all by the two big Earth-based forces that destroy roads: erosion by water (either of the road itself or the underlying road bed) and frost heaving. The low lunar gravity also lessens the wear and tear caused by heavy vehicles. I'd be interested to know if someone has some real numbers on the rate of crater formation on the Moon...? I strongly suspect that any road on the Moon would last far longer than a similarly-constructed, similarly-used Earth road. TenOfAllTrades(talk) 16:13, 24 August 2011 (UTC)

There are regular meteor showers that we see hitting the Earth's atmosphere. They also pelt the Moon without the atmospheric benefit of burning them up before they hit the surface. It isn't just the meteor strike that is a problem on the Moon. Because of the low gravity, the ground explosion travels much farther and with far less resistance than on Earth. So, a single meteor becomes a shower of smaller meteors over a very wide range. -- kainaw™ 17:09, 24 August 2011 (UTC)

Yes, I am aware of those facts, but I still think that you're overestimating the severity of the problem. The moon collects something like 1 ton per day of material (mostly dust), over its surface area of about 40 million square kilometers. If we assume a two-lane roadway 10 meters wide, that's 0.01 square kilometers of road surface area per kilometer of road length. Per year, we're looking at about 91 mg of meteor material per kilometer of road. If we assume 100 mg of meteor arriving at 50 km/s, that's 125 kJ deposited energy per kilometer of road: equivalent to about 30 grams (one ounce) of TNT. If you put that in one spot on the road, then yes—it will do some damage; probably enough to close a lane of traffic until a patch crew gets out to it. If that hits as a hundred 1 mg particles (much more likely), there will just be some scoring and chipping of the surface. If they're finer dust, you won't even see the effect without a microscope.

If we consider the ejecta and generously assume that the dust kicked up by an impact exceeds the mass of the original meteor by a factor of one million, we're looking at just 100 kg of dust spread on each km of road; call it a nearly-negligible 10 grams of fresh dust per square meter, per year. Finlay McWalter's excellent source below further strongly supports such a conclusion. TenOfAllTrades(talk) 19:20, 24 August 2011 (UTC)

We can gain some insight as to the wear on artificial objects from the Lunar Laser Ranging experiment. In the 40 years these have been on the Moon, they're still sufficiently intact and reflective for bouncing lasers off them to be effective (one project was, it seems, defunded in 2009, but not for want of mirror). This paper quotes another paper saying micrometeoroid damage to such objects as having "the fill-factor of craters on an exposed surface to be ∼ 10⁻⁴ after 40 years, dominated by craters in the 10–100 µm range." Both of these factors suggest that the micrometeoroid damage to something insensitive like a precast concrete slab would be trivial, and surely dwarfed by the wear from vehicles. -- Finlay McWalter ☻ Talk 16:44, 24 August 2011 (UTC)

The Nazis-in-space film you mentioned is probably Iron Sky. -- Finlay McWalter ☻ Talk 15:55, 24 August 2011 (UTC)

I would vote for driving rather than hopping around (losing one's lunch in a spacesuit would be a problem). I wonder just what the effect of micrometeorites would be over say a 40 year period. The impressive crater collection on the Moon is the result of billions of years, with no rain or wind to soften or obscure them. The Surveyor 3 probe was exposed on the Moon for 31 months before the Apollo 12 crew visited it, and brought back portions of it, and it did not appear to have been hit by micrometeorites, although the Wikipedia article says little about the surface of it. A book says "There are no definite impacts of micrometeorite origin found on the returned Surveyor 3 equipment." A website however says some of the microscopic craters might have resulted from micrometeorites, among the many from the Apollo landing 160 meters away and kicking up dust, creating a sandblasting effect. There were some particles kicked up by the Apollo landing. All the retroreflectors left on the moon in the 1960's and 1970's are reportedly still functioning, so meteorites have not knocked them out. If space is full of micrometeorites, one would expect them to frequently damage satellites. How often does that happen? I expect that it a lunar road were bulldozed, or paved with concrete (lunar soil plus water makes concrete), it would look much the same decades later, with potholes not being much of a problem in a road many miles long. Edison (talk) 16:23, 24 August 2011 (UTC)

I think you're right. It would be a pain in the whatever to build roads or tracks on the moon. They could be destroyed by any Act of God at any moment. Otherwise, I guess Maglev (transport) would be a nice idea. Very little need for fuel and oxidant. You only need electricity (powered by the sun). Given the low gravity, it would be more fuel efficient then on earth.

Is it a good idea to use the hopper craft to transport a great amount of materials and products? I mean something like our cargo ship. Or can we build a very big moon truck to crawl on the moon surface?

Yes, Iron Sky. Thank you. I just love the moon highway idea. If only I could ride an old-fashioned bike on the moon ..........

http://www.youtube.com/watch?v=4KEueJnsu80 (1:12) -- Toytoy (talk) 16:11, 24 August 2011 (UTC)

According to NASA, the first footprints on the Moon will be there for a million years.^[7] Compared to the vicissitudes of Earth, the Moon should not be harsh on roads. Of course, wheeled vehicles themselves can still tear up dirt roads like anywhere else, and the expansion/contraction issues with pavement must be pretty nasty, but I'm sure you can work out something.

On the other hand, with 1/6 the gravity, I suppose ideas like monorails are easier to implement - the main appeal being that if you have a perfectly straight rail and a near frictionless pivot, and no air, you can go as fast as you dare. Wnt (talk) 16:44, 24 August 2011 (UTC)

The footprint is a point but the road is an area. Today's space around earth is a much safer place then it was billion years ago. I still think that from time to time, a very small meteor may hit the road surface and cut it off. I think the inner planets have already "vacuumed" the space clean enough. But there are still meteor showers on earth. -- Toytoy (talk) 17:11, 24 August 2011 (UTC)

Right, but even on earth, roads are only a tiny fraction of a % of the surface, and we have billions living here who use them. A few roads on the moon are an incredibly small target which would be unlikely to sustain significant damage from extralunar impacts for centuries. Googlemeister (talk) 18:35, 24 August 2011 (UTC)

I have a suggestion:

1) Use a "road", but of an unconventional design. Instead of being paved, have it be full of lunar sand (although you might want concrete barriers at the edges to contain the sand). This road should withstand micro-meteors quite well, although the sand may need to be replenished from time to time.

2) Have the vehicles be solar/electric powered snowcats. That is, they would have deep treads that dig into the sand and move it, to provide forward motion. I wouldn't expect such a vehicle to be very fast on the Moon, but hopefully quite reliable.

3) Since the turning radius would be quite large, you would want the roads to be relatively straight, between bases. Also, design the vehicles to be reversible, so they can just pivot the seats around and drive in the opposite direction, either once they reach their destination or if they need to "turn around" mid-trip. Note that such a vehicle could also operate where there are no roads, provided there's a path through the boulders. StuRat (talk) 19:29, 24 August 2011 (UTC)

A second suggestion, for longer distances, is a flying vehicle, with a launch device which would shoot it into near orbit from the ground and thus greatly reduce the requirements for on-board fuel, perhaps only using the rockets when landing. A large gun could be used to launch into space, although the g-forces involved would likely make this method inappropriate for passengers or sensitive cargo. Also note that such a ballistic trajectory should be aimed to miss the target base by a safe distance, in case the retros failed to fire, so the base wouldn't be damaged by the impact. StuRat (talk) 20:04, 24 August 2011 (UTC)

A cable car would possibly be easy to implement.It also is probably more energy efficient than a road or some flying vehicle propelled by rockets. 88.9.108.128 (talk) 22:08, 24 August 2011 (UTC)

I like the cable car idea. Given the low gravity nature, you may not need very thick cables. However, the moon is still likely to have moonquakes. You may need very specialized lubricant oils and moonquake-resistant structure to build a cable car on the moon. Otherwise, the view can be truly amazing! -- Toytoy (talk) 16:42, 25 August 2011 (UTC)

What about simply orbiting very close to the Moon's surface? The Moon has no atmosphere to speak of, so if you were going fast enough you could orbit even as low as a foot above the ground. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 00:26, 29 August 2011 (UTC)

Why do flies hit windows repeatedly without realizing they can't get out that way?

Perhaps nobody knows. But I'll ask anyway.

Jonathan ^talk 18:29, 24 August 2011 (UTC)

That is a great question. I hope you get a good answer because I also do not know and would love to find out. Googlemeister (talk) 18:31, 24 August 2011 (UTC)

Just a guess: they are relying on visual cues, absent due to the transparency. Memory and/or learning may just be insufficient, reasoning may be present but reaching the wrong conclusion—that another try might work.

Do they hit the same spot each time, or a slightly different point on the pane of glass? If they hit the same spot—how much time elapses between strikes?

Obviously I don't know the answer to the question posed. But I think these factors may be applicable. Bus stop (talk) 18:40, 24 August 2011 (UTC)

If the answer is transparency, wouldn't they be able to see the reflection of sunlight off of it? Maybe the flash is bright enough to disorient and temporarily blind them and render them unable to alter their path quickly enough. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:39, 31 August 2011 (UTC)

I find it most useful to think of insects as very sophisticated robots. They don't "realize" things, they execute programs. Their visual-navigation programs have evolved to work well in situations that they commonly encounter, but don't work so well when they encounter glass, which doesn't occur in nature. Looie496 (talk) 18:43, 24 August 2011 (UTC)

Footnote: see sphexishness for Daniel Dennett's way of explaining this. Looie496 (talk) 18:45, 24 August 2011 (UTC)

Glass does occurr in nature!!! D-:< Whoop whoop pull up ^{Bitching Betty | Averted crashes} 00:40, 29 August 2011 (UTC)

I'll add a related puzzling question. How can a House Gecko simultaneously walk on a glass window and repeatedly bang its head on the glass trying to eat the bug on the other side ? This is odd because as far as I can tell, they have to learn that they can walk on glass and yet they never seem to learn that they can't eat things through it or fight other geckos through it. This also seems to be the case for the Gekko gecko too. Sean.hoyland - talk 18:54, 24 August 2011 (UTC)

I second the notion of animal instincts being like simple computer programs. In this case, it's like two subroutines, one with the logic "if you can feel it with your foot, then try to walk on it" and another with the logic "if you can see food with your eyes, then try to eat it". These two subroutines do not interact. Higher animals have intelligence with true learning, but there is very little learning in the lower animals. StuRat (talk) 19:09, 24 August 2011 (UTC)

An applicable factor as simple as the deficiency, relative to the human counterpart, of the visual mechanism, could also be a heavily contributory factor. What it would have to learn is that a plane was impenetrable, but that is a difficult problem when the knowledge that the barrier is planar is not known. If it cannot see the glass—how can it know that it exists as a "pane"—that is, in the planar geometric configuration? This is why I am concerned with whether it is hitting the same spot on the glass each time. Bus stop (talk) 19:13, 24 August 2011 (UTC)

I observe that they don't hit in quite the same spot on subsequent attempts for the most part, they hit a few inches away each time in what looks like a random fashion. Googlemeister (talk) 20:34, 24 August 2011 (UTC)

House flies (and many flying insects) display positive phototaxis when trapped or stressed. Thus a tried and true method to get flies to exit is to close and shutter all windows, turn off all lights, and open one window completely. The flies will happily leave in an hour or so, unless they are otherwise attracted to a food source or oviposition site. Basically, the flies' instincts are tuned such that (more light)=(more freedom). This is a good rule, but windows mess it up. SemanticMantis (talk) 20:53, 24 August 2011 (UTC)

But, unfortunately, there are other insects, such as wasps, which see dark places as a good spot to build nests, so they might fly right in. StuRat (talk) 22:04, 24 August 2011 (UTC)

Blowflies, when trapped in a room will indeed fly in circles around it and bat their heads on windows repeatedly as they try to get out. I notice that house flies never exhibit this type of behaviour. That's why they call them house flies: your place is home. Myles325a (talk) 10:12, 25 August 2011 (UTC)

Hurricane Irene on Weather Underground: computer models much scarier than 5-day forecast

Why is Weather Underground's 5-day forecast so much further East than its computer models? Given the path and intensity projections, and the flooding potential for a coast-hugging path, I am wondering whether Irene has the potential to rival Katrina's damage.

"If the core of Irene stays offshore, the mid-Atlantic and New England may escape with a few hundred million dollars in damage from flooding due to heavy rains and storm surge. If Irene hits Long Island or Southeast Massachusetts, the storm has the potential to be a $10 billion disaster.... I'll be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Wednesday) at 4:30pm EDT. Fellow wunderground meteorologists Shaun Tanner, Tim Roche, and Angela Fritz will also be there. Listeners can email in or call in questions. The email address to ask questions is broadcast (at) wunderground.com." -- Jeff Masters[8] 76.254.20.205 (talk) 19:16, 24 August 2011 (UTC)

The two pages look approximately the same to me -- tracking near Cape Hatteras, then landfalling around New England. What particular discrepancy are you looking at? As for damages, Hurricane Katrina caused $81 bn in damages (an order of magnitude higher than Masters' $10 bn estimate quoted) and struck an area that sits largely at or below local water level, geography that isn't found much along Irene's projected track. — Lomn 19:22, 24 August 2011 (UTC)

Huh! I wonder if they just updated the 5-day. About 15 minutes ago it looked at least 100 miles East of all but one of the computer models, with the center projection not intersecting the Connecticut coastline. I wish the models had shifted East instead of the forecast shifting West, but that is the order in which you'd expect them to update. I would take the consensus advice of the wunderground blog commenters and not wait to buy preparations (plywood, etc.) Please see http://www.nhc.noaa.gov/HAW2/english/disaster_prevention.shtml and http://www.aoml.noaa.gov/hrd/shutters/index2.html for more information. 76.254.20.205 (talk) 19:30, 24 August 2011 (UTC)

It seems about right to me. The models are within the track forecast cone for Irene. Titoxd^{(?!? - cool stuff)} 20:02, 24 August 2011 (UTC)

I will be in Washington on Sunday and Monday. What should I expect? I do know thunderstorms but Hurricane is word only associated to news films. --Stone (talk) 20:36, 24 August 2011 (UTC)

If you have a flight landing in Washington D.C. Sunday, it could easily be delayed or even cancelled. What time Sunday?

Sunday lat in the afternoon.--Stone (talk) 19:13, 25 August 2011 (UTC)

Incoming flights to Washington, D.C. have been restored, but Tom Hendrics, Sr. V.P. of Air Transport Association says it could take a 2-4 days to work through the delay backlog. About 10,000 flights were canceled. 76.254.20.205 (talk) 16:41, 28 August 2011 (UTC)

76.254.20.205 (talk) 21:34, 24 August 2011 (UTC) New York is not exempt from being struck by major hurricanes, capable of doing catastrophic damage Count Iblis (talk) 20:53, 24 August 2011 (UTC) Let me give a pointer to NOAA's hurricane page. In the material for each storm you can find a section called "Forecast discussion", that explains what each important model predicts, and how the information is combined to reach a forecast. It is pretty much always a judgement call to some degree. Looie496 (talk) 21:42, 24 August 2011 (UTC)

Thanks! "THE NEW ECMWF SHOWS MUCH MORE AMPLIFICATION OF THE TROUGH...WHICH HAS RESULTED IN ITS TRACK SHIFTING OVER 100 MILES TO THE WEST"[9]. I guess that is the change I was noticing above. Someone should explain to NOAA and NWS about the caps lock key, although in this case I suppose it's appropriate. 76.254.20.205 (talk) 21:52, 24 August 2011 (UTC)

If I remember correctly, they are constrained to use all caps for backwards compatibility for older receptor equipment. Titoxd^{(?!? - cool stuff)} 07:26, 26 August 2011 (UTC)

Bladder Cancer

Is there any evidence that the human papilloma virus can cause bladder cancer? Ref. an article in the UK "Daily Telegraph" newspaper on 19 August 2011 about a woman academic, a non-smoker, who had a successful operation.Pensioner.bsc (talk) 00:30, 25 August 2011 (UTC) — Preceding unsigned comment added by Pensioner.bsc (talk • contribs) 22:59, 24 August 2011 (UTC)

Single cases are really almost never meaningful. The idea has been around for a long time and a number of studies have been done yielding a mix of results, summed up in an authoritative 2008 review, PMID 18815920, as "The possibility that infection by human papilloma virus (HPV) is a risk factor contributing to bladder cancer has been investigated but no definite conclusions have been drawn.". Looie496 (talk) 23:13, 24 August 2011 (UTC)

Thanks for the reference.Pensioner.bsc (talk) 00:46, 25 August 2011 (UTC)

The question I would have is: "how does the HPV get to the bladder" ? Does it travel up the urethra ? Bacteria causing bladder infections can do so, especially in women, where the urethra is shorter. However, the bacteria can presumably grow in the urethra, using urine for it's nutrient supply, and slowly spread, while a virus would need to find living cells to infect, in order to spread. This would cause rather noticeable warts in the urethra, causing pain and or urine blockage, wouldn't it ?

I suppose the other alternative is the virus traveling via the circulatory system, but, in this case, why would it only go to the bladder ? StuRat (talk) 23:26, 24 August 2011 (UTC)

I agree, if the urine flow is always outwards from the bladder there would be no problem, but one might speculate that the flow could be briefly backwards when the bladder relaxes after urinating.Pensioner.bsc (talk) 00:29, 25 August 2011 (UTC) — Preceding unsigned comment added by Pensioner.bsc (talk • contribs) 00:27, 25 August 2011 (UTC)

I believe there are valves in place to prevent that. StuRat (talk) 06:28, 25 August 2011 (UTC)

Thanks, from the articles I have looked at on HPV eg Viral disease there is just an "association" with urinary problems. It could certainly get into the circulation via cuts and abrasions (eg in sex and dentistry) and thence to organs vulnerable to it, but the common cause of HPV infection and bladder cancer I would conclude is an impaired immune system.Pensioner.bsc (talk) 00:03, 27 August 2011 (UTC)

I can think of another way they could be related: Perhaps people who have lots of unprotected sex with multiple partners both tend to be exposed to HPV and (bacterial) urinary tract infections, and those are what cause the bladder cancer ? StuRat (talk) 06:03, 27 August 2011 (UTC)

Well in the case mentioned in the "Daily Telegraph" I think she was just unlucky, the immune system deteriorates with age, making you more vulnerable to carcinogens of all types, eg burnt toast, barbecued food. Also in women thyroid deficiency hypothyroidism is more common than in men and that may impair the immune system, but this is getting way beyond my expertise!Pensioner.bsc (talk) 20:05, 27 August 2011 (UTC)

Burnt toast has been carbonized. Carbon is not a carcinogen. If it were, we would be virtually made of tumors. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:43, 31 August 2011 (UTC)