Wikipedia:Reference desk/Archives/Science/2010 January 22

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January 22

Pelvic cavity capacity

Is there the same amount of space inside a mans pelvic cavity as in a womans? What is the capacity of spare space in liters (assuming empty bowel) —Preceding unsigned comment added by 79.76.218.43 (talk) 01:06, 22 January 2010 (UTC)

The linked article might be a good starting point, although I didn't see where it answers your question directly. Based strictly on anecdotal observation, I would say it varies by individual. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:01, 22 January 2010 (UTC)

See also Pelvis#Sexual_dimorphism, although again there's no direct answer. Neurotip (talk) 10:13, 22 January 2010 (UTC)

It might be more straightforward to compare the openings rather than the volume, which would have to have the top and bottom specified, as well as the outer contours. Women need a large opening for childbirth, but a large volume is not so clearly needed for that purpose. In Iowa, "citizen soldiers" apparently need both a large pelvic volume and a large pelvic opening. The state seal specifies an image of a citizen soldier "with a plow in his rear." Edison (talk) 16:08, 22 January 2010 (UTC)

Why can't water freeze when salt is added?

Why can't water freeze when salt is added? —Preceding unsigned comment added by 71.194.113.40 (talk) 01:35, 22 January 2010 (UTC)

It's not that it can't freeze, it's just the freezing takes place at a lower temperature than normal. This is referred to as Freezing-point depression. Truthforitsownsake (talk) 02:17, 22 January 2010 (UTC)

Here's a non-wiki explanation of salt lowering the melting point.[1] And isn't the Arctic Ocean covered with frozen brine? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:22, 22 January 2010 (UTC)

No, seawater at atmospheric pressure freezes by salt exclusion, so sea ice is mostly fresh water. Dragons flight (talk) 02:33, 22 January 2010 (UTC)

I assume saltwater has to freeze at some point above absolute 0. Presumably it would be in the 10-to-20 degree area, the point where salting ice doesn't work? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:06, 22 January 2010 (UTC)

If you try to freeze a deep body of salt water what you get is a layer of fresh water ice above a slightly salter body of water. That process of separating into fresh water ice and saltier brine is preferred until the brine gets substantially saltier than sea water. If you could isolate that brine, then you could eventually freeze it, but different ions freeze at different temperatures. It would take till around -35 C before the remnant solution of calcium and sulfate ions finally freezes and you are left with a true solid (though actually sulfate can push past -55 C if there aren't enough of the right kinds of cations present). Dragons flight (talk) 04:23, 22 January 2010 (UTC)

So the specific answer to the OP's question is that it can freeze, at around -55 C at the lowest, which is about -67 F if I used the right formula. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:41, 22 January 2010 (UTC)

No, -55 C is exactly -67 F. Cuddlyable3 (talk) 14:34, 22 January 2010 (UTC)

See Freeze distillation: it's very hard to get ice with impurities in it. --Carnildo (talk) 00:45, 23 January 2010 (UTC)

Prilosec and Prevacid

Whats the simliarites and differences between two.

Basically, would like to know since my current prescription to generic prilosec is about to run out. At the same time I was told I had to see my doctor in order to get more of it. Which I totally not worth it in the long run since I have tried Prevacid in the past as well. The reason why I'm on Prilosec at the moment because insurance stopped covering Prevacid and had to switched to Prilosec at that time. Also, my parents are on Prilosec as well. One of them is in the same situation as me and has decided to take OTC Prilosec as the another one takes as well.

Believes that it for now.

Thank you, in advance. —Preceding unsigned comment added by Jessicaabruno (talk • contribs) 01:42, 22 January 2010 (UTC)

Hi Jessica, we really can't answer this question because it almost certainly will constitute medical advice - even if those drugs may be over-the-counter medicine. You should definitely talk to your doctor - it is his or her job to explain these sorts of things to you. If you don't understand their explanation, keep asking them until you understand it. We can link you to the Prilosec and Prevacid articles, but you should not rely on Wikipedia for anything more than a very basic overview of these drugs - especially since we can't guarantee the accuracy of those articles. Nimur (talk) 02:25, 22 January 2010 (UTC)

Thank you, Nimur and didn't know that Wikipedia had a policy on this.--Jessica A Bruno (talk) 20:04, 22 January 2010 (UTC)

In the U.S. a pharmacist will generally explain the ingredients in such medicines and their effects. Edison (talk) 15:59, 22 January 2010 (UTC)

You might want to observe if you gulp some air while coughing, thus increasing the pressure. If so, you might want to tell your doctor just in case he forgets to ask about it. 95.115.144.18 (talk) 20:29, 22 January 2010 (UTC)

Genetic mutations, human electromagnetic fields and electronics

Some people say that electronic devices seem to malfunction more often or fail sooner when they're nearby. Is it theoretically possible that a person with the "right" genetic mutations could emit an electromagnetic field strong enough to damage devices or disrupt their functioning? NeonMerlin 02:46, 22 January 2010 (UTC)

Yes, I expect so. Electric eels are capable of producing large electric fields, so it is certainly possible. It is ridiculously unlikely that that is the case, though. It would require a very large number of mutations, too many to occur in one person at any realistic probability, so it would take many generations to happen. Far more likely is that they are suffering from confirmation bias. --Tango (talk) 03:28, 22 January 2010 (UTC)

No! Hell no! We'd be easily able to measure a field that strong - and we can't. Electric eels can do that - but they have these enormous, easily spotted organs in their bodies for doing that. They evolved those organs for a reason - why would humans evolve the ability to zap electronics? No - this is just another one of those ridiculous claims people make when they are sad little people with nothing remarkable to say about themselves who wish to feel important and special. If this were true, we'd know all about it by now. I'm sure the James Randi foundation would be happy to pay out a million dollars to anyone who could demonstrate this ability in a proper scientific test. Please tell this to people who claim to have this mysterious ability - and watch as their claims shrink to "well, sometimes it happens" - which is a clear case observer bias. SteveBaker (talk) 04:23, 22 January 2010 (UTC)

There is a difference between a theoretical impossibility and something that is merely highly improbable. There is no law of physics that forbids humans that emit large EM fields, so the answer to the OP's question is "yes, it is theoretically possible". --Tango (talk) 04:54, 22 January 2010 (UTC)

Well - theoretically in the sense that it's theoretically possible for someone to be born with blue and green striped skin and six heads. An electric eel has to use a dedicated organ that occupies 80% of it's body volume to produce the pulse it generates! Even that 500 volts at 1 amp wouldn't be anywhere close to enough to leap several feet through the air to zap a piece of electronics. Remember - electric eels live in salty, highly conductive water...but the trick that we're talking about here has to work through air which is a damned good insulator. You can put your phone in front of the 5,000 volts produced in a TV set and you're not taking ANY risk of damaging it! Even if some random human mutation were somehow to produce an organ able to do that - the odds of it happening are so spectacularly astronomically unlikely that we can be very confident that it won't happen over the life of the universe. Electric eels gained this ability through slow piece-by-piece evolution over millions of years - not in one might flook. We can also be sure that the person afflicted with this mutation wouldn't survive the self-induced shock after they first activated this organ. We can also be sure that this thing would occupy several cubic feet of body space - so it would be REALLY noticable. Someone with this ability would be a freak-show mutation - not just some ordinary looking person. Please - we get enough of this crap in the world - let's not extend any hope to the bozo's who claim this kind of crap. No, it can't happen - period. SteveBaker (talk) 05:32, 22 January 2010 (UTC)

Scientific method comprises formulation of hypotheses, such as the OP reported, followed by rational enquiry into what needs to be, and what can by experiment be, validated. Characterising an unproven hypothesis as crap claimed by bozo's who are "sad little people with nothing remarkable to say about themselves who wish to feel important and special" is not scientific. See the articles Theremin about an electronic device that can be affected by a person at a (short) distance and Radar about electronic devices that can be affected by secondary radiation from a person at a great distance. Light is electromagnetic radiation that when reflected from a person can in particular circumstances upset the function of a low-light camera. Cuddlyable3 (talk) 14:27, 22 January 2010 (UTC)

So theramins and radar are driven by (to quote our OP) "a person with the "right" genetic mutations could emit an electromagnetic field"? No - theramins work by the change in capacitance of the air caused by the person and radar works by the person reflecting electromagnetic waves - not emitting them. Reflection of light is not emitting light - and you don't need genetic mutations to operate a theramin, or to be visible to radar. Nothing in your previous response has any bearing whatever on the OP's question. SteveBaker (talk) 17:58, 22 January 2010 (UTC)

If you restrict the meaning of "to emit"[2] to mean not just "to send forth" but additionally "to generate independantly" then reflecting is as you say not a process of emitting. However energy is never emitted without some conversion of incident energy. I described the emission from a radar target as secondary radiation because it is not necessarily simple reflection; rather resonance, phasing and absorption are all factors that determine Radar cross-section. A THEREMIN (spelling) operator by capacitive coupling becomes part of a r.f. resonating circuit. Since the OP asks about any theoretical possibility of a human mutation disrupting an electronic device, we can conceive of some mutation of a person's shape and/or tissue such that his/her quantitative influence on a sensitive device is changed enough to disrupt its function. An example might be a clock oscillator for a high-precision timing device: the oscillator is shielded well enough to hold its frequency within specification when the device is held in an ordinary hand but Mr Mutant is blessed with an extraordinarily large and conductive hand. When he picks up the timing device its function is disrupted out of specification. Of course that is a subtler effect than an electric arc that zaps electronics several feet away and is generated somehow like in an eel's electrocytes but if that fishy fantasy was ever relevant to the OP's question then you have laid it to rest. BTW the second sentence of my post "Characterising an unproven...." has indeed no bearing on answering the OP's question because it is entirely about your post, from which I quoted. Cuddlyable3 (talk) 18:29, 23 January 2010 (UTC)

Another way to look at it is that the devices are nearby because they are used more frequently, and the greater usage might shorten their functional life. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:57, 22 January 2010 (UTC)

One possible article is Electrokinesis (ability). But more likely would be that the person misused the item, gave the item an electrostatic discharge possibly by wearing charged nylon pants, or spilled a drink on it. Graeme Bartlett (talk) 08:25, 22 January 2010 (UTC)

I read an account of a particular woman who could cause data processing equipment to malfunction. It was found to be due to electrostatic discharge due to the clothes/shoes she wore allowing a charge to build up. Plastic shoe soles would insulate more than leather soles. Walking across some carpets can build up several thousand volts of charge on a person, sufficient to make a large and painful spark when he touches something grounded. Such a discharge could damage many electronic devices. But a trash can dragged across the rug could also build up a static charge. Nothing special about it being a human. In an electronics lab I have visited, workers wear grounding electrodes to make sure their shoe soles do not insulate them from the floor, but which have some fuse capability so they would not carry a large current to electrocute the worker. There is nothing special about a human in relation to a Theremin. I expect a cabbage or a piece of aluminum foil or a bag of dirt moving near it could also affect the capacitance and cause an audible effect from a Theremin. My grandfather could never wear a wristwatch, because they stopped working, so he carried a pocket watch. I believe this was due to the amount or nature of his sweat rather than any electric effect. Edison (talk) 15:57, 22 January 2010 (UTC)

Indeed, it's very possible to zap an electronic device with a static charge - but the OP says (a) "when they are nearby" - not necessarily touching or holding the device - which rules out anything but a really severe spark jumping an unlikely distance - and (b) that this is a "genetic mutation" that causes an electric field to be "emitted" - which doesn't cover merely accumulating static by wearing the wrong kinds of clothes and shoes because our genes don't control that. But even then, a piece of personal electronics like a cellphone or something isn't going to be zapped like that while it's in its case with all of the wires hooked up to the battery. Certainly humans can damage electronics - throwing them violently at the nearest brick wall will do that with a fair degree of reliability! That's not what we're being asked here. Can someone with a genetic mutation emit an electromagnetic field strong enough to destroy nearby electronics? To which the answer is a very definite "No!". Saying otherwise and throwing in random references to theramins (which are specifically DESIGNED to pick up the presence of a nearby human) does a disservice to our questioner by merely muddying the waters. SteveBaker (talk) 17:58, 22 January 2010 (UTC)

The original poster was not specific about what "electronic devices" are malfunctioning, but another possibility is that the original complainant was talking about a radio or a baby monitor, and as you walk around the radio you certainly will block the signal in some places, possibly causing a lot of static, depending on the character and strength of the inbound signal. Alternatively, if the complainant is carrying a cellular phone, there's the "gallop" interference that is often heard on nearby speakers (including my computer speakers) every 5 or 10 minutes as the cell phone checks in with the local tower; maybe that's the "malfunctioning" that is being complained about. Not related to genetic mutation, except, I guess, for all the genetic mutations in the past that have led our bodies to be physically large enough to interfere with radio signals. Comet Tuttle (talk) 18:24, 22 January 2010 (UTC)

Let me just point out that eels live in water, which is highly conductive. An electric eel out of the water is unlikely to have any noticeable effect on electronic equipment nearby. It would be like an AC outlet with nothing plugged into it. Looie496 (talk) 18:28, 22 January 2010 (UTC)

And significantly, electric eels only live in salt water which is much more conductive than fresh water. The very few 'electric' fish that live in fresh water are only able to deliver relatively puny belts compared to electric eels. (See Electric skate, for example). SteveBaker (talk) 18:39, 22 January 2010 (UTC)

The Electric eel lives in the Amazon and other rivers - fresh water. 92.29.31.202 (talk) 21:10, 22 January 2010 (UTC)

Electronic devices can be quite sensitive, and humans can gather quite a lot of static electricity. When my mobile rings next to my computer mouse the later sends a couple of mouse-wheel-events. On times I don't need to actually touch the touch-pad of my notebook to move the mouse, it is sufficient to move my finger some distance above without contact. When we had to build circuits at university from TTL chips we always could test them previous to switching the real power on. I simply touched the plus and minus wires with the fingers of my left and right hand respectively (or the other way round, didn't make a difference). It was only a few mV but enough to reliably check the logic of the circuit. I don't know how it worked, but it worked reproducibly every time I tried. And no, I'm not joking. 95.115.144.18 (talk) 20:11, 22 January 2010 (UTC)

I think it less likely that millivolts from your fingers energised your TTL circuits (which would need at least some 2-3 volts to start current in base-emitter junctions) than that the binary high "1" external input(s) you used to test the logic raised the positive supply via the on-chip input protection diode(s). When working with TTL circuits I too noticed that devices could work with their +ve supply pin disconnected. Cuddlyable3 (talk) 18:50, 23 January 2010 (UTC)

Once, I took an alarm clock with an LCD display and barely any battery power left, and it appeared to become clearer when I placed it near me. I think I also posted this as a question on the RefDesk, and it's perhaps possible that the small variations in EMF fields had a small effect on the almost as small remaining battery energy. ~AH1^(TCU) 02:21, 23 January 2010 (UTC)

Nope - because your body is basically a big bag of salty water, radio waves are affected by passing through you. When the battery is low, it takes a bigger radio signal to make your clock produce sound - and strategically placing your body in the right place can concentrate the radio waves enough to make a difference - of course putting it in some other position will block the waves. But it's nothing to do with magical power emanating from your body. SteveBaker (talk) 05:03, 23 January 2010 (UTC)

The bit about testing logic circuits is good science because the human body can act as a cell, producing a few mV. This is easily shown on a galvanometer or a sensitive multimeter. Years ago, people used to claim that I could make faulty electrical and electronic devices work just by coming near them. A colleague was reputed to have the opposite effect. It was all Confirmation bias, of course, I was just good at guessing what was wrong, and the colleague was good at making inappropriate adjustments. Dbfirs 07:35, 23 January 2010 (UTC)

immunity and cancer

cancer is caused by our own cells , so immunity of body does not effect it. is that so? or immunity of body effect the spreadin' of cancer. in todays date is there any cure of cancer except the lasers? are lasers efficient enough to kill cancer cells from root? I M NOT ASKING A MEDICAL ADVICE, its just zeal

Have a good read of our lengthy cancer article. It's not a simple topic. Also there are many Management of cancer options available today which are discussed in that article, not sure i've ever heard of lasers being one of them. Vespine (talk) 04:04, 22 January 2010 (UTC)

Immunity: no, that's not so. See Cancer immunology. Neurotip (talk) 10:08, 22 January 2010 (UTC)

Cancer arises from our own cells, not caused by our own cells. Immunity and other body responses is important in regulation of most types of cell growth and tumors including cancer suppression. There are many treatments that can cure cancer. Surgery can cure many cancers. Chemotherapy can cure some cancers. Radiation can cure some cancers. Most treatments of most serious diseases have some risk and some cost. The ratios of likelihood of cure to likelihood of harm vary enormously for different cancers, different people, different treatments. alteripse (talk) 23:00, 22 January 2010 (UTC)

Research suggests that deoxycholic acid may have cancer-fighting capabilities. ~AH1^(TCU) 02:16, 23 January 2010 (UTC)

Thousands of substances have "cancer-fighting capabilities" in some cancer model or system. It's a long way from that to calling it a cure. alteripse (talk) 15:22, 24 January 2010 (UTC)

Red dwarfs: proportion to all stars

According to the best current estimates (the current consensus), what percentage (range of percentage) of the stars in the universe are red dwarfs? —Preceding unsigned comment added by 63.17.40.163 (talk) 04:55, 22 January 2010 (UTC)

Our article on red dwarf stars doesn't mention this, but there is a reference in Stellar classification#Class M. It gives a fraction of 76% (for main sequence stars in the solar neighbourhood). That tally only includes stars of absolute magnitude 16 or brighter; the proportion of Class M stars would rise further if dimmer stars were included. TenOfAllTrades(talk) 05:06, 22 January 2010 (UTC)

Thank you -- I saw that figure, but thought perhaps the solar neighborhood (being not necessarily typical of all regions) might not be representative of the universe, which is the context of my question. Also, the article doesn't state what percentage of class M stars are red dwarfs, so there were two uncertainties. So: can anyone answer this regarding only red dwarfs, and in the context of the universe (instead of class M stars in the solar neighborhood)? —Preceding unsigned comment added by 63.17.40.163 (talk) 05:34, 22 January 2010 (UTC)

Class M stars are red, and by numbers they would be almost all dwarfs, with just a few giants. If you count in the solar neighbourhood, you can make sure that you can see them. Are you interested in brown dwarfs? Graeme Bartlett (talk) 08:17, 22 January 2010 (UTC)

So I guess the question is: Is the solar neighborhood representative of the universe in regard to the proportion of class M stars? If so, then approximately 75% ("almost all" of 76%) of all the stars in the universe are red dwarfs. If not, then what is the answer? —Preceding unsigned comment added by 63.17.45.118 (talk) 10:04, 22 January 2010 (UTC)

Oh -- and the figure of 75% would have to be adjusted higher (a little? a lot?) because of this: "That tally only includes stars of absolute magnitude 16 or brighter; the proportion of Class M stars would rise further if dimmer stars were included." Incidentally, I'm asking this because the consensus is that red dwarfs would not have planets capable of nurturing intelligent life, so the fact that they are (apparently) at least 75% of all stars is relevant to the discussion of life in the universe. —Preceding unsigned comment added by 63.17.45.118 (talk) 10:17, 22 January 2010 (UTC)

That used to be the consensus, but I've seen it challenged quite a lot in recent years. The habitable zone for a red dwarf is much closer in and much narrow, but it does exist. --Tango (talk) 12:31, 22 January 2010 (UTC)

...and of course that "habitable zone" is for "life as we know it" and not "life as we don't know it but could imagine" or "life as we don't know it and couldn't even imagine". Anywhere where there is a reasonable quantity of energy and matter, there could be some kind of life. SteveBaker (talk) 18:22, 22 January 2010 (UTC)

Oh, of course. There is no point discussing life as we don't know it since we don't know anything about it. We can hypothesise about certain types of life (silicon instead of carbon, ammonia instead of water, etc.) but there's no reason to believe live as we don't know it would fall into the "could imagine" category. --Tango (talk) 19:42, 23 January 2010 (UTC)

PS. Another reason to concentrate in life as we know it is that we are very unlikely to be able to make any kind of contact with any intelligent life unless it uses radios in the same way we do, and it stands to reason that life like us is more likely to have technology like ours. --Tango (talk) 19:44, 23 January 2010 (UTC)

It's relevant to the discussion of life, but proportion of habitable stars is only one parameter of the Drake equation. Given that there are at least four more parameters at which we can only guess the values (life, intelligent, signaling, duration), this one discussion shouldn't be enough to make or break any theories about extrasolar life. — Lomn 13:56, 22 January 2010 (UTC)

Well, three of those four unknowns are not strictly relevent - the probability of there being extrasolar life is not the same thing as the probability of extrasolar intelligent life that is able and willing to talk to us right now! So if all you care about is whether there is extrasolar life at all then there are far fewer unknowns. We have a pretty solid idea of how many extrasolar planets there are. We'll soon be able to analyse the atmospheres of extrasolar planets and calculate what percentage are good for "life as we know it" and "life as we don't know it - but could imagine" - and at that point there is pretty much only one serious unknown - which is the probability of an abiogenesis event occurring (or the probability of a panspermia kind of event). Sadly, since we currently have no idea what our abiogenesis event was or whether panspermia is even a reasonable hypothesis, there is a big enough error bar on that number to make the result of the Drake equation come out to zero or infinity or anything between! Good news for science fiction authors - not so good news for the SETI folks! SteveBaker (talk) 18:22, 22 January 2010 (UTC)

We have a pretty good idea about how many large planets there are. We're just getting started with Earth-sized ones. --Tango (talk) 00:01, 23 January 2010 (UTC)

I'm the OP -- I referred specifically to "intelligent life." I believe bacteria could be found just about anywhere, but it's a long way from bacteria to evolved intelligence, which could not evolve -- much less be nurtured (let's be serious) -- on a red dwarf's planet no matter what the planet was like. See Habitability_of_red_dwarf_systems (which, incidentally, gives an uncited range of 70%-90% "of all stars"). —Preceding unsigned comment added by 63.17.87.54 (talk) 05:20, 23 January 2010 (UTC)

I wouldn't be so sure. We only have a sample size of 1 to draw all our conclusions about where intelligent life can arise, so those conclusions are very unreliable. --Tango (talk) 19:42, 23 January 2010 (UTC)

coil spring life

when a coil spring is subjected to repeatative load, how long it will sustain for same load —Preceding unsigned comment added by 59.160.18.209 (talk) 09:04, 22 January 2010 (UTC)

It's impossible to say without knowing the properties and dimensions of the material out of which the spring is made, not to mention the load itself.--Shantavira|^{feed me} 12:09, 22 January 2010 (UTC)

Springs made of Steel, Phosphor bronze or Beryllium copper exhibit linear-elastic behaviour i.e. they obey Hooke's law provided their material's yield strength is not exceeded. An example of a device which depends on steel's unchanging elasticity (quantified by Young's modulus) is a Tuning fork. The article Metal fatigue lists factors that could shorten coil spring life under repeated cycling. Two applications where this is critical are steel coil springs in automobile suspensions and valve gear.Cuddlyable3 (talk) 13:55, 22 January 2010 (UTC)

Calculating Pressure

I came across a sum in my textbook, which asks the reader to calculate the pressure at the bottom of a sealed cylindrical container fully filed with water which has been laid down on its side. The answer at the back is given as: 1/2ρgh+Ρ where P is air pressure at sea level. Can anyone explain why it's 1/2ρgh instead of simply ρgh? 117.194.224.21 (talk) 09:12, 22 January 2010 (UTC)

Do you mean the average pressure on the circular end? Is the printed answer just an average? The pressure will be P at the top of the circular end, and P + ρgd at the bottom. Have I misunderstood the question? Dbfirs 09:20, 22 January 2010 (UTC)

If I understand what you mean by "laid down on its side", then the depth of water is the diameter of the cylindrical. The given answer would then make sense only if the cylinder was twice as tall as it was wide (before being laid down), that is, h=4r. 124.157.247.221 (talk) 12:45, 22 January 2010 (UTC)

Golden syrup versus sugar

Which is the healthiest option as a sweetener in porridge: golden syrup, white sugar or brown sugar? Why?

Darkhorse06 (talk) 09:15, 22 January 2010 (UTC)

It partly depends on what you regard as 'healthy'. Moderation in all things! It is unlikely to make any noticeable health difference unless you use these in large quantities. All these are rather high in calories, all are basically sugars of some type. Brown sugar is slightly less refined than white sugar.
See Also: sweetener, golden syrup, white sugar, brown sugar. You might also like to consider: Honey and Maple Syrup--220.101.28.25 (talk) 09:44, 22 January 2010 (UTC)

There's also (a recent invention), low GI sugar, at least where I live. [3]. However low in this case is 50, which isn't really that much less then the 65 for ordinary white sugar [4] and similar to what 220 said it's unlikely to really make that much of a difference. See also [5]. In particular, presuming you aren't using that much in you porridge it probably doesn't make that much an overall difference to the GI of the breakfast although at least you're consuming porridge rather then something like cornflakes or cocoa pops which likely have a high GI themselves. You may want to consider something like a banana or some other fruit instead of any normal sweetener Nil Einne (talk) 10:15, 22 January 2010 (UTC) That's Coco Pops (no 'a') on Wikipedia 'Cuz'. ;)) --220.101.28.25 (talk) 11:00, 22 January 2010 (UTC)

I don't know enough about the subject, the benefits of honey may have been overstated in its article, as it is mostly simple sugar. 67.243.1.21 (talk) 15:45, 22 January 2010 (UTC)

It's mostly sugar - and pound for pound it must have almost identical calories to sugar - but what makes it seem worse is that a level teaspoonful of sugar has an awful lot of air in it because of the large crystals - but a level teaspoonful of honey is all honey. SteveBaker (talk) 17:40, 22 January 2010 (UTC)

Except for the part that's water... It would be interesting to see the calories per unit volume for a scoop of standard-sized sugar crystals (where the non-sugar bits are air) and honey (where the non-sugar bits are water). --Jayron32 04:21, 23 January 2010 (UTC)

Simple WP:OR. I have a cookbook which tells me 1 cup of white sugar is 200 g. 1 cup is 250 ml in NZ as in a number of other Commonwealth countries. So 800g/L. It also gives 2 tablespoons being 30g. We don't use the funny Australiantablespoons (which I admit are neater since they are 4 teaspoons and so can divide into 2 tea for 1/2 and 1 tea for 1/4 albeit makes 1/3 trickier). That means 30ml/30g or 1g/L. Clearly quite a big difference although I'm guessing it's for simplicity as much as anything.

Now nothing for honey but since it's a liquid, finding the density is hopefully quite easy and sure enough honey says "Honey has a density of about 1.36 kilograms per liter (36% denser than water)". Honey of course is easier to measure but is likely a much more variable product. My bag of white sugar says it has 1700kJ/100g (sugar says 1,619 kJ). My jar of honey say 1210kJ/100g while honey says 1,272 kJ. Close enough but I'll use the second one first since our density figure is evidentally for US honey and the figure for energy density is from the USDA. (My cookbook is Edmonds Cookery Book so measures NZ ingredients.) 17000kJ/kg * 0.8 kg/L = 13,600 kJ/L. 12720kJ/kg * 1.36 kg/L = 17,299 kJ/L. The sugar wins as SB expected, by about 1.27 times.

Ideally we need a better range for density, particularly for sugar (I know density isn't a good word but let's not worry about that) and you can probably find something on the internet but I'm lazy so I'll just fudge it and use what I have. You can do your own experiments of course particularly if you have an accurate e.g. digital scale.

Anyway if we take the energy density range 16190kJ/kg * 0.8 kg/L = 12,952 kJ/L and 12100kJ/kg * 1.36 kg/L = 16,456 kJ/L. Throwing in the tablespoon figures we get 16190kJ/L and 17000kJ/L obviously. Although personally I wonder if the range is a little higher, presuming 200g/250mL is resonably accurate perhaps say 175g/250mL-225g/250ml is a better range presuming you measure accurately and your sugar isn't highly packed (which doesn't tend to be too much of a problem for white sugar).

Note, if measuring smaller quantities it's likely to be more variable in any case. Oh and if you want funny old units like calories, you'll have to do the calculations yourself I'm a funny old unit free zone (the general simplicity and ease of calculation I've somewhat demonstrated here). (Admitedly the calorie is metric so isn't quite a bad unit as some stuff like Fahrenheit and does make some sense.)

Nil Einne (talk) 05:08, 23 January 2010 (UTC)

Heroin addiction

How many injections of heroin would it take for a new user to become addicted?

In some cases, one. -- Aeluwas (talk) 09:50, 22 January 2010 (UTC)

Yes, it would likely vary betweeen people. See Heroin, addiction and drug addiction, especially the Addictive potency section for more data. --220.101.28.25 (talk) 09:58, 22 January 2010 (UTC)

Definitely, as little as one is enough in many cases. I know a guy who was intelligent, successful, etc who did the "I'll just try it once to see what it's like" thing - ten years later, he's still a total mess. That stuff is evil. SteveBaker (talk) 17:37, 22 January 2010 (UTC)

Isn't it even possibly deadly on the first injection, for example if one has a low tolerance for drugs in general? The sad case of your friend sounds like something Garrison Keillor said once, about people "who make a bad decision and then stick with it." ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:06, 22 January 2010 (UTC)

It isn't possible to become physiologically addicted to heroin after a single exposure, it takes dozens at least. Psychological addiction is a different matter, but that's very difficult to quantify. The data show that physiological addiction is quite a bit more rapid for fast-acting psychostimulants such as crack cocaine than for heroin -- the flip side is that the withdrawal symptoms produced by heroin addiction are probably the most unpleasant of any type of drug. Looie496 (talk) 18:19, 22 January 2010 (UTC)

Our Heroin article only alludes to answers of this simple question; could a knowledgeable editor add the answer to that article? Comet Tuttle (talk) 18:31, 22 January 2010 (UTC)

(ec) Interesting...but of course what starts out as 'merely' a psychological addiction will pretty soon become a physiological one if not handled immediately. Having seen it happen, it's hard to believe that what made him go back for another fix was purely psychological...but if that's what it takes then I've gotta say that even intelligent, well-grounded, happy people can get psychologically addicted after the first shot. What the underlying cause of taking the second shot is - I have no clue. SteveBaker (talk) 18:34, 22 January 2010 (UTC)

The trouble with psychoactive compounds is that the distinction between physical dependence and psychological dependence is moot blurry - physiological effects manifest as perturbations of neurochemistry (among other physical dependence effects). The extent to which neurochemical dependence is separate from psychological dependence is hard to clearly define. There's no shortage of research on this, and it isn't clear to me that a scientific consensus exists. Nimur (talk) 18:44, 22 January 2010 (UTC)

The physiological addiction Looie mentioned is related to a change in opioid receptor regulation, which is possible to measure quantitatively. Psychological addiction is much harder to measure quantitatively. --Mark PEA (talk) 12:30, 23 January 2010 (UTC)

I don't know who posted that image from the Nutt et al paper, but it should be noted that the diagram is slightly flawed since the addictivity of cocaine doesn't take crack cocaine into consideration, which is possibly more psychologically addictive than heroin. Also, the methodology of that study isn't as scientific as one would assume for a Lancet paper. --Mark PEA (talk) 20:16, 22 January 2010 (UTC)

I have seen a bbc documentary created from the results of that study, and they claimed a difference in effect between crack and powder cocaine could not be established. —Preceding unsigned comment added by 80.226.1.7 (talk) 03:14, 23 January 2010 (UTC)

From the study's own discussion: "Crack cocaine is generally deemed to be more dangerous than powdered cocaine, but they were not considered separately in this study". What this means is that the participants who were asked to rate the drug harms were told to consider "cocaine" to mean "cocaine (in powder and freebase form)". I guess the narrator/producer of that programme misread that and thought that it meant they didn't consider there to be a difference, but there most certainly is. --Mark PEA (talk) 12:30, 23 January 2010 (UTC)

I grabbed it from our Heroin article and pasted it there — insert obligatory hectoring to be bold and go fix it or challenge its inclusion in that article, etc. Comet Tuttle (talk) 21:20, 22 January 2010 (UTC)

I'm fine with leaving it in there. It is borderline WP:OR to question the validity of peer-reviewed scientific research. --Mark PEA (talk) 12:30, 23 January 2010 (UTC)

Lancet chart

Drug	Mean harm	Acute harm	Chronic harm	I.V. harm
Alcohol	1.40	1.9	2.4	0
Tobacco	1.24	0.9	2.9	0

Why is tobacco to the left of alcohol in the Lancet graphic above? Don't lung cancer deaths due to nicotine addiction far outnumber deaths due to alcohol? 99.25.112.22 (talk) 05:53, 23 January 2010 (UTC)

In an earlier post I had a bit of a jab at the methodology of that paper, but you can see some of the raw data on the page of that picture. --Mark PEA (talk) 12:30, 23 January 2010 (UTC)

Alcoholism is far more common than lung cancer. According to alcoholism, "In the United States and western Europe 10 to 20% of men and 5 to 10% of women at some point in their lives will meet criteria for alcoholism". I personally have never known anybody with lung cancer, but I've known at least a couple of dozen people whose lives were impaired by alcohol. Looie496 (talk) 16:13, 23 January 2010 (UTC)

The plural of anecdote is not data. "Each year, a staggering 440,000 people die in the US from tobacco use. Nearly 1 of every 5 deaths is related to smoking. Cigarettes kill more Americans than alcohol, car accidents, suicide, AIDS, homicide, and illegal drugs combined."[6] (emphasis added) 99.38.150.198 (talk) 18:53, 23 January 2010 (UTC)

It appears that while tobacco has greater chronic (long term) effects, the authors felt that alcohol's short term danger (drowning in your own vomit) makes alcohol the more "dangerous" drug. Really though, it's a bit like comparing apples to oranges. Do you want to slowly kill yourself by smoking for 40 years, or do you want to go binge drinking on the weekends and run the (small, but not insignificant) risk every week of not waking up on Monday? I don't think we should be reading too much into the small difference in the "harmfulness" numbers of the two without looking at other aspects of the drug. The chart makes it clear that both can be quite harmful. Buddy431 (talk) 21:16, 23 January 2010 (UTC)

So, should tobacco be to the right of heroin on the chart? Why or why not? 99.38.150.198 (talk) 03:34, 24 January 2010 (UTC)

No, because with heroin there is a far higher risk of respiratory depression, thus it has a higher "physical harm" rating. --Mark PEA (talk) 13:24, 24 January 2010 (UTC)

What makes respiratory depression worse than total number of deaths? 76.254.71.123 (talk)

Many fewer people use heroin than smoke. Causing more total deaths doesn't mean it's more dangerous to the individual user. Rckrone (talk) 03:35, 25 January 2010 (UTC)

Unless the individual user also pays taxes, is part of a health insurance pool, or is susceptible to the secondary comorbidities of nicotine addiction such as tuberculosis? 76.254.71.123 (talk) 00:54, 26 January 2010 (UTC)

What? No. To an individual, smoking one cigarette is far less harmful than injecting 10mg of heroin. The only exception would be an extremely unlikely scenario such as the person has overdosed on an opioid antagonist. --Mark PEA (talk) 18:39, 26 January 2010 (UTC)

Speed

What is the maximum attainable speed, Please? —Preceding unsigned comment added by 123.237.193.11 (talk) 19:19, 22 January 2010 (UTC)

The maximum for what? Cycling records, Water speed record, Land speed record, Motorcycle land speed record? Assuming you mean the fastest possible speed for anything, then why not read Speed, in which you will find the answer. Fences&Windows 19:36, 22 January 2010 (UTC)

It's just below the speed of light ("c"). As mentioned in the Upper Limit on Speeds section, it would take an infinite amount of energy to accelerate an object with mass to the speed of light. Since you don't have an infinite amount of energy available, you can get closer and closer by continuing to accelerate, but you'll always be just a little slower than c. Comet Tuttle (talk) 19:33, 22 January 2010 (UTC)

It's not only below the speed of light. You can actually reach the speed of light. You only need to find an adequate amount of anti matter and transform yourself to light.95.115.144.18 (talk) 19:47, 22 January 2010 (UTC)

I thought we didn't do people's homework for them. Fences&Windows 19:38, 22 January 2010 (UTC)

This doesn't sound at all like a homework question to me. Thanks for the mention of the Speed article; I just corrected the intro where it had been claiming that matter can reach c. Comet Tuttle (talk) 19:43, 22 January 2010 (UTC)

This all sounds kind of familiar, but I'll ask anyway: photons travel at the speed of light, in part because they are "nearly" 0 mass. I might argue that they are not exactly 0 mass, just very small. So, is the speed of light really the upper limit for speed, or is it some other number that's just slightly more than the speed of light? Or is it more like limit formulas, such as 1/n, whose limit is 0 as n approaches infinity, but never actually reaches 0? Ya follow? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:06, 22 January 2010 (UTC)

Bugs, photons are presently understood to have exactly zero rest mass (that is, what we conventionally consider "mass"). There's no "nearly" about it (in absence of some verifiable and reproducible experimental result that suddenly upsets a lot of physics). c is the upper bound, which can be reached in the idealized "light in a vacuum" state, though this is never fully found in nature. Note, though, that "speed of light" becomes confusing terminology here -- if photons were found to have mass, and thus traveled at less than c, the photon's speed would be the "speed of light". In particular, the upper bound of c is borne out in quantum entanglement, which though resulting in changes that appear to propagate at speeds greater than c (perhaps immediately), does not transmit information. For transfer of information to work with quantum entanglement (quantum teleportation is one such application), a classical (i.e. c-limited) communication is also required. On the other hand, the notion of the tachyon as an FTL particle is still floated about, though it's presently considered highly unlikely to exist in a causality-breaking form. — Lomn 20:31, 22 January 2010 (UTC)

I'm not so sure that they literally have 0 mass, but it doesn't really matter, because as far as we know, the speed photons travel (in reference to whatever medium they are in) is the fastest known velocity of any object within that medium (be it water, vacuum, or whatever). So if the upper bound is slightly higher than c, it doesn't really matter as it's unattainable. ←Baseball Bugs ^{What's up, Doc?} carrots→

Bugs: PLEASE stop guessing - we all make mistakes - but we really do work hard not to guess. Before you answer, either be very sure you know the answer - or look it up. Look up the Lorentz transform in this handy dandy encyclopedia we have on the interweb and you'll see: $\ gamma={\frac {1}{\sqrt {1-{\frac {v^{2}}{c^{2}}}}}}$. That nice Mr Lorentz said that at some speed 'v', the mass of the object is it's rest mass multiplied by gamma...things get heavier as they are accellerated towards the speed of light. So if you know the rest mass and the speed - you can figure out the relativistic mass. Now, if v is exactly equal to c (ie, if the object is moving at exactly the speed of light) then v²/c² is exactly 1.0 - so gamma is one divided by the square root of zero...one over zero is either undefined (if you're a mathematician) or infinity (if you are a physicist) - so at exactly the speed of light, an object would become literally infinitely heavier than it was at rest. That means that it's mass would be literally bigger than the mass of the entire universe. That's not going to happen. However, we know that the photon does move at exactly the speed of light - and it doesn't have an infinite mass - it has a small but perfectly measurable relativistic mass while it's moving at the speed of light. So we can calculate the rest mass of the photon by dividing its relativistic mass by Lorentz's gamma factor. But if it's moving at the speed of light - then gamma is infinity and its rest mass is it's fairly small relativistic mass divided by infinity. Any number divided by infinity is...zero. So the rest mass of the photon MUST be precisely zero...not a teeny tiny bit above zero...it has to be EXACTLY zero. Now, when you say "it doesn't matter if it's a tiny bit above c" - you have to consider what you just said. If v is even the tiniest bit bigger than c then v²/c² is just a hair bigger than 1.0 - but the number inside the square root of the lorentz transform is 1-v²/c² - so that would be a negative number. The gamma factor would be one divided by the square root of a negative number...which is a complex number - and complex number never, EVER show up as real world quantities. Hence, speeds of even the most microscopic amount above c are proven to be clearly impossible by very basic arithmetic. It's not even something to discuss. SteveBaker (talk) 03:13, 23 January 2010 (UTC)

Thanks for the explanation. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:19, 23 January 2010 (UTC)

As Lomn correctly explained above, the zero mass of photons is not a speculation, but an experimentally verified result. If there were a non-zero mass, even a very tiny one, it would have implications that contradict observation. They are massless particles and this theoretical principle is part of the Standard Model. Nimur (talk) 21:19, 22 January 2010 (UTC)

It is not the case that, in every medium, light travels faster than anything else. See Cherenkov radiation for what can happen when things go faster than the local speed of light. Algebraist 21:02, 22 January 2010 (UTC)

According to that article, there is a type of electromagnetic radiation that travels faster than "light" in that particular medium. However, "light" is a form of electromagnetic radiation. Unless they're restricting "light" to mean visible light, which is merely a subset of all the possibilities for electromagnetic radiation. Right? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:52, 23 January 2010 (UTC)

That article does not say that. It doesn't even say anything like that. I don't know where you're getting your ideas from now. Algebraist 03:23, 23 January 2010 (UTC)

When a body moves at a speed say .8c and another body at .5c (In opposite directions) Then the relative speed between them exceeds C while the maximum speed attainable is C .Doesn't this contradict the above statement PS this Isn't a homework 123.237.193.11

Don't forget time dilation! Once who was traveling around at a close enough speed of light can have time run 1,000x slower for him, so that he perceives himself traveling at 1000c (even though only going at 0.99999c) Googlemeister (talk) 20:19, 22 January 2010 (UTC)

Yes, that was a fundamental to one of Einstein's theories. Although in an absolute sense those two objects are speeding away from each other (or let's say from their common point of origin) at a net of 1.3c, from their own viewpoint they are not. Basically, nature corrects for this apparent paradox. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:31, 22 January 2010 (UTC)

Yes on time dilation, no on perceiving 1000c (or anything greater than c). Every frame of reference is consistent with c being the maximum speed. Various tricks might be shown as to how a traveler might conclude that he's gone 1000c but they break down when shifts in frames of reference are taken into account. For example, consider the spaceship that travels from Earth to a star 1000 light years away, experiencing 1 year on its local clock. This is the sort of thing you might say equates to "1000c", right? But consider: the radio pulse broadcast from Earth simultaneous to the departure of the ship won't arrive 999 years later; it's already come and gone by the time the ship gets there. — Lomn 20:44, 22 January 2010 (UTC)

(after edit conflict) @Googlemeister: Time is perceived to run at "normal rate" whatever the speed of travel, so no traveller can perceive himself to be travelling at 1000c. What he perceives is length contraction of objects not travelling at the same speed. (I suppose in some circumstances, that might amount to the same thing.)

@BaseballBugs: A wrong calculation by a "stationary" observer would add 0.8c to 0.5c and wrongly conclude that the relative velocity was 1.3c. This faulty calculation would not be supported by the observations of either of the travellers. Dbfirs 20:48, 22 January 2010 (UTC)

Precisely. That observer might be standing on the point of origin. He would see them pulling away at their respective speeds and conclude they were receding from each other at faster than light speed. But the ones receding wouldn't see it that way. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:54, 22 January 2010 (UTC)

Yes, perhaps I misunderstood what you intended by "absolute sense". It is the faulty assumption about how to add speeds that creates the paradox. I suppose it is true to say that, in the frame of reference of the stationary observer, the rate of increase of separation of the travellers is 1.3c, but this cannot be interpreted as a relative speed observable by either of the travellers. Dbfirs 21:23, 22 January 2010 (UTC)

Quantum mechanics and probability

Hello again, and thank you in advance. As I always say when I ask these stupid questions, I am here as an amateur philosopher and only have a relatively superficial understanding of physics, and a slightly better but still probably inadequate understanding of maths, so you'll probably have to talk down to me a fair bit lol. But I'm curious anyway, and would appreciate it very much if you could aid my understanding.

My question is about the nature of probabilities in quantum mechanics. When there is something uncertain (like beta decay or wave function collapse or some other thing I kind of know about but don't really understand), is the probability of this uncertain thing occurring something that is known for sure? Like we might not know when a nucleus will emit an electron, but do we know at all times the probability that it will emit an electron?

That's a specific example but I'm asking the question generally. In quantum mechanics, are probabilities always certain quantities?

Thanks much! Dan Hartas (talk) 19:20, 22 January 2010 (UTC)

No the probabilities may or may not be correct they are not always certain quantities . see Interpretation of quantum mechanics —Preceding unsigned comment added by 123.237.193.11 (talk) 20:19, 22 January 2010 (UTC)

I'm not sure I understand, I think maybe I didn't ask the question right. I wasn't asking about whether there was disagreement on the actual values or mechanisms of these probabilities, I was wondering whether science sees them as even having actual values. I'm talking specifically in terms of the Copenhagen interpretation I think. Dan Hartas (talk) 20:40, 22 January 2010 (UTC)

If I understand the question correctly... (and assuming I understand this aspect of QM correctly)... let's take an example of something that is considered fundamentally probabilistic according to QM, like the decay of a nucleus of something radioactive. For any individual atom, when it will decay is fundamentally unknowable. I am not even sure if it can be expressed in a sense of "in every second, there is a 1/million chance that this could decay," but maybe someone can clarify that. However, taken as a group, the probabilities average in directly predictable ways according to the stability of the substance—thus we have half-lives, which are pretty iron-clad expressions of the rate of decay over a relatively large number of atoms. The half-life is not an expression of the likelihood of any given sample to decay in that period, but an observed expression of what that rate of decay will be, if that distinction makes sense. (The half-life article discusses this better terms than I am, I recognize.) --Mr.98 (talk) 00:39, 23 January 2010 (UTC)

And as something else possibly relevant... if you are interested in how weird probabilities can get in QM, I find Bell's theorem and its experiments to be pretty interesting food for thought. It basically rules out the possibility of hidden variables—e.g., the idea that the uncertain aspects of QM are not being secretly carried around by the particles, invisible to the observer but "known" to the particles themselves (or known in a "God's eye view"), but are, in fact, ontologically uncertain. (There are other interpretations of Bell's theorem, to be sure, but that it rules out local hidden variables seems to be the consensus, as I understand it. I am not a physicist, however!) --Mr.98 (talk) 00:43, 23 January 2010 (UTC)

Bell's theorem doesn't rule out global hidden variable theories—but then, I think those come with just about the same conceptual baggage as any other interpretation of QM. To the OP, you may find this explanation of Bell's theorem, and some of the debate around that time interesting. —Preceding unsigned comment added by Zazou (talk • contribs) 13:01, 23 January 2010 (UTC)

A quantum mechanical system is always in a definite state, described by a state vector. When time passes that state evolves (in the original nonrelativistic quantum mechanics) according to the hamiltonian of that system as described by the Schrödinger equation. The hamiltonian can be deduced from the laws of physics. The initial state must be measured or set up; it is usually impossible to know entirely. If however both are known, the future state vectors of the system are entirely determined by this.

The Copenhagen interpretation now says, that whenever a property of the system is measured, the state vector of the system is projected (collapsed) onto one of the base states corresponding to the possible measurement results. The square of the length of the projection is proportional to the probability for that measurement result. So if the initial state, the hamiltonian, the amount of time passed and the base vectors of the measurement are known, the probabilities for each measurement can be deduced from this.

Other interpretations give different answers. Hidden variables theories will claim that the probability for one measurement result is one and zero for all others and the full initial state vector cannot be known. Everett claims that the probabilities are all one; the state vector never collapses, it only couples with the measurement device to form a single quantum mechanical state which contains amplitudes for all measurement results. Mr. Coleman explains this way better than I ever could: http://media.physics.harvard.edu/video/index.php?id=SidneyColeman_QMIYF.flv —Preceding unsigned comment added by 80.226.1.7 (talk) 03:05, 23 January 2010 (UTC)

About human evolution

Starting from the article History of the Americas and found somewhere the theory that humans could have migrated to the Americas 40k years earlier than they did because siberia was infested by spotted hyena. This set my mind wondering and left me with two questions:

How long would human populations need to evolve without contact with each other to 1) not being able to genetically intermix any more, and, 2) not being susceptible to the other ones endemic diseases? Well, I know, it depends, but are there any theories or estimates out there? 95.115.144.18 (talk) 19:39, 22 January 2010 (UTC)

I saw a TV show recently that said that homo sapiens and the neanderthals probably came from common ancestors in Africa. It's possible they could still have interbred. But if you can find an estimate on how long ago those branches split, that will give you a rough minimum figure - which I would guess is at least in the hundreds-of-thousands of years. Evolution among larger creatures is slow. But nature has had all kinds of time. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:02, 22 January 2010 (UTC)

Why does the size of the creatures matter? Surely it is the length of a generation (that is, the average age of reproduction) that matters. There does seem to be a correlation between size and lifespan, but not a particularly strong one. --Tango (talk) 20:12, 22 January 2010 (UTC)

Yes, rate of reproduction. Bacteria and viruses, and also insects, reproduce quickly, so mutation and evolution is way much faster in those critters. And they happen to be very small. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:25, 22 January 2010 (UTC)

Not being at all susceptible to the other's diseases would take a very long time - we can catch diseases from birds (see Bird flu) and we separated from them hundreds of millions of years ago. --Tango (talk) 20:12, 22 January 2010 (UTC)

Doesn't the virus responsible for spreading bird flu need to be a mutated version in order to infect humans though? Otherwise there would have been a much much higher number of people who catch bird flu. Googlemeister (talk) 20:17, 22 January 2010 (UTC)

The rate of mutation would be much faster in bugs that reproduce frequently, as suggested by Tango in his adjustment of my earlier comment. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:27, 22 January 2010 (UTC)

Chimps are a somewhat better analog, because there are some diseases that we still have the same receptors for, despite 6 million years of evolutionary distance. We are too distant to reproduce with them (probably), but not too distant to share some of the same diseases. --Mr.98 (talk) 23:33, 22 January 2010 (UTC)

Back in the 80s, it was theorized that AIDS originated among the apes. The ever-outspoken Frank Zappa said, "What I'd like to know is, who's fluking those monkeys???" ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:23, 23 January 2010 (UTC)

Take care with the questions you ask... Sometimes there is an answer. --Jayron32 04:12, 23 January 2010 (UTC)

Fascinating. "Chuman" vs. "Humanzee"? More to the point, how about "Chump"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:19, 23 January 2010 (UTC)

You guys/gals do realise Mr. 98 already linked to that right? Anyway more seriously since the issue did come up even if not seriously, Origin of AIDS says as I had expect, bushmeat is usually considered the culprit, from when hunting or butchering the animal. And before anyone makes the joke, yes okay if you really did get AIDS from fucking a monkey (although I'm not sure if we could even get SIV from monkeys) you'd probably say you got it from bushmeat. Sorry didn't read Simian immunodeficiency virus properly, it appears HIV-2 did come from monkeys and [7] also suggests they're a high risk. Given their size [8], if you did try doing a Sooty Mangabey I doubt the monkey would survive and it's likely to be rather bloody, i.e. a rather high risk activity. Nil Einne (talk) 05:16, 23 January 2010 (UTC)

longjack

is longjack and Tongkat Ali the same thing? and does longjack contain all this: Eurycoma Longifolia Jack / Tongkat Ali / Malaysian Ginseng / Pasak Bumi? —Preceding unsigned comment added by 67.246.254.35 (talk) 19:59, 22 January 2010 (UTC)

Yes they are but Muhammed Ali is different Tongkat Ali= Eurycoma longifolia 123.237.193.11 —Preceding unsigned comment added by 123.237.193.11 (talk) 20:13, 22 January 2010 (UTC)

Consumer Medication Guides

What should I look for?

Thinking about getting updated one because the current one that I have is Worst Pills, Best Pills. It is good, but it doesn't have everything that I'm looking for. At the same time it last update was 5 years ago and that's the one that I have. —Preceding unsigned comment added by Jessicaabruno (talk • contribs) 20:08, 22 January 2010 (UTC)

Personally I like The Pill Book. I like the type of information it provides and the way it presents it. It seems to be updated regularly too. I'm not a pharmacist; I'm just sharing my opinion as a consumer. Generally, you can find out what readers have to say about a book at websites that feature book reviews, such as Amazon's. --173.49.12.84 (talk) 15:14, 23 January 2010 (UTC)

life on other planets

I was reading a question that involved red dwarf stars and the drake equation and a thought occurred to me. Given that all life as we know it is carbon based, and seemingly dependent upon either O2 or CO2 for life, is it possible to determine what the odds are that life in other forms exists within our solar system, say floating around 100 miles into Jupiter, or bacteria sized organisms oozing around on Venus, considering that we have not explored these areas which would have had a completely different evolutionary path? It does not seem like we have a feasible way to determine that life does not exist in those locations considering that any life we can experiment on would be adapted to live on our planet, not in those other areas. Googlemeister (talk) 20:15, 22 January 2010 (UTC)

I have a hunch there's an article that would explore that topic. You could start with Life. Also, for that matter, it's possible we ourselves have introduced our own microbes to those areas where we have sent our various satellites and rovers - which might be able to adapt - and might even consume existing life forms there - or merge with them. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:20, 22 January 2010 (UTC)

We have an article on SETI. Scientists do not rule out the possibilities of life - even life which is biochemically similar to earth life - within our own solar system. The probability of it existing is low, and the probability we might find it, even it if it does exist, is even lower - but it is part of the motivation for the study of planets and moons within our own solar system. One class of targets in recent years have been the moons of Saturn and Jupiter. You might like to read Extraterrestrial life#Direct search, Extraterrestrial life#Extraterrestrial life in the Solar_System, and the proposed Terrestrial Planet Finder for extrasolar planets. Nimur (talk) 21:24, 22 January 2010 (UTC)

See Hypothetical types of biochemistry. Comet Tuttle (talk) 21:25, 22 January 2010 (UTC)

Carbon is uniquely capable of producing a wide variety of complicated compounds with properties that are really conducive to constructing living things - there are good chemical reasons for supposing that life elsewhere would have to be carbon-based. That in turn puts limits on the temperature range over which life is reasonable - and it's a small step from that to requiring there to be liquid water. But I have to STRONGLY disagree with Baseball Bugs that our microbes "might even consume existing life forms there - or merge with them". That would be like making a Mac program run on a Windows computer. The odds of these other life-forms having compatible DNA is very, very tiny indeed. The only chance that there might be compatibility would be if our life came from their planet or their life from ours (See panspermia) - which means that they aren't really "alien" life at all - just a distant offshoot of our evolutionary tree.

But that doesn't mean that there can't be some really freakishly weird aliens out there. What if a species of fairly conventional aliens - similar to humans, perhaps - learned how to do really serious nanotechnology - or to produce artificially intelligent self-reproducing robots. Suppose then that over eons, the original species went extinct. That would allow either a race of intelligent robots - or an entire ecology of nano-mechanical "bacteria" to appear and colonize their planet. They might eventually learn to evolve and forget who made them. They might well not depend on carbon, water and reasonable temperatures. We would see them as exceedingly alien creatures!

I'm sure that even stranger things are possible - and as I said in a previous thread, there is life as we know it, life as we don't know it (but could imagine) and life as we can't even imagine. (Who said that? I can't find it in Wikiquotes.) By definition we can't guess at what might be in the third category. SteveBaker (talk) 02:26, 23 January 2010 (UTC)

There are many places in the solar system where it has been proposed where life may exist. Here is a partial list. ~AH1^(TCU) 02:10, 23 January 2010 (UTC)

J. B. S. Haldane said: Now, my suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose ... I suspect there are more things in heaven and earth than are dreamed of, in any philosophy. (Source for this version of the quote is Advanced Banter). -- Jack of Oz ... speak! ... 20:30, 23 January 2010 (UTC)

For a certain fraction of the population, that's a great pickup line! SteveBaker (talk) 01:38, 24 January 2010 (UTC)

{{fact}} Name one time when that line has actually worked! --Tango (talk) 02:48, 24 January 2010 (UTC)

You don't necessarily need compatible DNA to merge (and you certainly don't for eating, you just need vaguely similar biochemistry with matching chirality - that last point is an interesting one, though, some molecules essential for human life have highly toxic mirror images, yet there is no reason for life on a different planet to match our chirality unless we have a common origin). Consider eukaryotes and mitochondria. While they do have compatible DNA (and have exchanged DNA over the years), I know of no reason why they couldn't maintain they symbiosis with vastly different genome storage mechanisms. --Tango (talk) 02:48, 24 January 2010 (UTC)

Preventing deterioration of rubber-made articles

Rubber tires (and generally things made of rubber) will deteriorate over time, even when they are not used. Are there ways to prevent rubber from deteriorating while in storage? --173.49.12.84 (talk) 21:17, 22 January 2010 (UTC)

Typically, avoid contact with direct strong light, extreme temperatures, and harsh chemicals, fumes, or abrasives. If you're seeking to preserve the rubber for very long periods of time, you could immerse it in some kind of nonreactive oil bath. To some extent, over long time scales, the rubber will self-react, breaking down its polymer chemical structure, resulting in a more brittle, less elastic material. Nimur (talk) 21:27, 22 January 2010 (UTC)

I'd go with a nitrogen (or argon) atmosphere, rather than an oil bath. IIRC, some of the components in rubber are oil-soluable. --Carnildo (talk) 01:16, 23 January 2010 (UTC)

Fellow antique car restorers often recommend Johnson's baby oil. It helps to keep rubber supple by preventing it from drying out - and can even go some way to restoring moderately dried out rubber parts as it's absorbed by the rubber and makes it swell, restoring flexibility. I didn't believe this - but I tried it on some of the rubber and plastic parts of my 1963 Mini - and it works! The stuff can dissolve rubber though - so use a small amount and test it on a bit that doesn't matter too much. Care is needed. SteveBaker (talk)

Surface temperature of planets and moons

Surface temperature can be measured by the infra-red coming off things. What are the surface temperatures of the various planets (solar and extra-solar) and moons. Are they all the same? 84.13.39.208 (talk) 23:54, 22 January 2010 (UTC)

Venus is way much hotter than the moon or Mars get on their worst days. It's like an acidic steam bath. Or as Carl Sagan once called it, "a thoroughly nasty place". ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:59, 22 January 2010 (UTC)

Go to List of Solar System objects, click on all the links and look in the infobox at the top right. The surface temperatures should all be there. --Tango (talk) 00:03, 23 January 2010 (UTC)

They are. Venus averages 735 Kelvin, which is pretty freakin' toasty. Mars, in contrast, never gets above freezing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:19, 23 January 2010 (UTC)

Bugs, in the name of all that is holy, would you please make an effort to provide a reference each time you post on the Reference Desk? If you had troubled to link to Climate of Mars in this case, for example, you'd see that the estimated high temperature on Mars is 27 degrees Celsius, which is well above freezing, and you would not have posted your inaccurate offhand opinion. Comet Tuttle (talk) 01:40, 23 January 2010 (UTC)

Tango already linked to List of Solar System objects, which led to my followup comment. Unless you wanted it twice (which you now have). ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:14, 23 January 2010 (UTC)

Specifically, the Mars page (reachable from List of Solar System objects - so there it is a third time) says the MAX is 268 Kelvin or minus 5 Celsius. By definition, that's below freezing. Now, if the the climate page you linked to doesn't agree, maybe you would want to look into reconciling those pages, or at least making the facts clearer. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:17, 23 January 2010 (UTC)

I suppose this should go on the Mars discussion, but anyway, Mars#Climate says the max is 20 degrees Celsius, so we have three different numbers from three different sources. Anyone here want to try and reconcile the error? — DanielLC 03:20, 23 January 2010 (UTC)

That astronomycafe link suggests a max temperature well above freezing. I wonder if there are some issues centering on just how "surface temperature" is defined? However, part of the OP's question was "Do all planets have the same surface temp?" and the answer is emphatically NO. To answer his more specific query - whether he can trust the details of the matter, as presented on wikipedia, is open to question. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:30, 23 January 2010 (UTC)

Thermal maps have been produced for some extrasolar planets, and it appears some are rather hot while others have plenty of atmospheric circulation going from warm to cold. ~AH1^(TCU) 02:07, 23 January 2010 (UTC)