Wikipedia:Reference desk/Archives/Science/2012 August 21

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August 21

Sticky Stuff Remover chemical identity

According to my online search, "Sticky Stuff Remover", for removing labels, has one active ingredient: CAS number 64742-47-8 - is this a mix of more than one chemical? Can it be obtained more economically in another form than "Sticky Stuff Remover"? --2.97.21.248 (talk) 02:39, 21 August 2012 (UTC)

Most adhesives are oil soluble, so just about any oil will work. WD-40 works, but, if you want something more pleasant smelling, try peppermint oil. Be careful not to get it on plastic, though, as it may also dissolve that. StuRat (talk) 02:41, 21 August 2012 (UTC)

CAS 64742-47-8 is a light petroleum distillate, so it's a mixture of low molecular weight hydrocarbons from crude oil. Apparently it's also sold as jet fuel , so I imagine that would be cheaper since you could buy it by the gallon. 203.27.72.5 (talk) 02:46, 21 August 2012 (UTC)

Somehow I doubt if the corner gas/petrol/filling station has it. StuRat (talk) 02:47, 21 August 2012 (UTC)

(edit conflict) Google turns up CAS number 64742-47-8 as "Hydrotreated light petroleum distillate" or other similar names. Here is one MSDS for it: [1]. It is basically hydrogenated kerosene, that is middle-weight hydrocarbons (say 8-16 carbons) which have been treated with hydrogen to remove any unsaturation (double/triple bonds). --Jayron32 02:50, 21 August 2012 (UTC)

Remember, the inactive ingredients make a difference too. The active ingredient is probably pretty dilute, and using it pure could damage paints and plastics. Given the answers above, it probably works about the same as using gasoline as a solvent. Unless you're looking to go through huge amounts of it, you're probably just better off shopping around for a cheaper off-brand version. Acetone-base nail polish remover also does a pretty good job with soft adhesives without being strong enough to damage most surfaces. 209.131.76.183 (talk) 14:08, 22 August 2012 (UTC)

Yea, but who wants to breath acetone fumes ? StuRat (talk) 19:51, 22 August 2012 (UTC)

Acetone fumes are probably no worse for health than petroleum distillate fumes. And the assumption that the active ingredient is dilute is in this case totally wrong. The product is essentially 100% hydrotreated light petroleum distillate [2]. 203.27.72.5 (talk) 21:00, 22 August 2012 (UTC)

Seems nasty to me: http://www.collectioncare.org/MSDS/Acetonemsds.pdf. I'll stick with peppermint oil, which is actually pleasant in small quantities. StuRat (talk) 21:14, 22 August 2012 (UTC)

I find butter works quite well for removing that annoying tacky residue from labels (and, ironically enough, from the gunk that ECG electrodes leave on your chest). Tonywalton ^Talk 23:02, 22 August 2012 (UTC)

Peppermint oil and butter fumes would certianly be less hazardous to your health than any synthetic or petroleum based organic solvents (though butter probably causes more deaths :P). With regard to acetone compared to the Sticky Stuff Remover, the MSDS toxicological information I have from my ChemAlert database gives:

• "Irritant. Over exposure may result in irritation of the nose and throat, coughing and headache. High level exposure may result in nausea, dizziness and drowsiness." for Sticky Stuff Remover inhalation and,
• "Irritant. Over exposure may result in irritation of the nose and throat, coughing, nausea, vomiting, weakness and headache. High level exposure may result in dizziness, drowsiness, incoordination and unconsciousness." for Acetone.

Unfortunately, there's no LC50 data for the Sticky Stuff Remover for comparison, but the acetone has LC50 (Inhalation): 44000 mg/m³/4 hours (mouse) which is quite high really. 203.27.72.5 (talk) 23:13, 22 August 2012 (UTC)

What is a Gaussian belt?

I ran across the term Gaussian belt in the Radio source SHGb02+14a article. Cursory Google searches turned up a few examples of the phrase in astronomical contexts. Is it related to spectral width? Thanks. Braincricket (talk) 03:39, 21 August 2012 (UTC)

It may be listed at List of things named after Carl Friedrich Gauss, but under a different name. Seriously, that dude has way too much stuff named after him. --Jayron32 04:58, 21 August 2012 (UTC)

A full-text search on ADS yields a single scientific paper with the phrase "gaussian belt" and it's not relevant to this radio source. As far as I can see, the phrase in the article is meaningless. I've commented it out until someone provides a reference or an explanation what it's supposed to mean. --Wrongfilter (talk) 10:26, 21 August 2012 (UTC)

orchid

can anyone tellme the name of this orchid??? http://en.wikipedia.org/wiki/File:Small-orchids.jpg

thanks 04:29, 21 August 2012 (UTC)Iskánder Vigoa Pérez — Preceding unsigned comment added by Iskander HFC (talk • contribs)

It's a Philippine ground orchid, Spathoglottis plicata. I have a picture of one in my backyard. :) -- OBSIDIAN†SOUL 04:49, 21 August 2012 (UTC)

Too bad you only have a picture of one in your backyard. The actual flower would be even prettier. :-) StuRat (talk) 04:52, 21 August 2012 (UTC)

Flowers wither, pictures are forever! ...and don't need watering. ;D -- OBSIDIAN†SOUL 06:35, 21 August 2012 (UTC)

Estimate altitude from environmental conditions

I have pressure in torr, temperature in C and relative humidity. Is there a standard way of estimating an altitude from this information? Barometric formula, Atmospheric pressure and International Standard Atmosphere all have good information, but not quite what I'm looking for. I'm going to look around the office to see if we have a copy of the ISO spec for the ISA. Otherwise it's looking like I may have to derive it myself. 209.131.76.183 (talk) 12:41, 21 August 2012 (UTC)

Formulas for estimating altitude are very fuzzy and tricky. The spherical cow approximations used in most calculations assume that the atmosphere is universal, constant, and unchanging: that is that there is a consistant set of atmospheric conditions whereby one could assume that altitude and air pressure are closely enough related to generate reliable data. That's how an altimeter works: it measures air pressure, assumes that surface air pressure is always the same value (it isn't) and that pressure decreases in a predictable way with altitude (again, if it does, it only does so in a very rough way). You're likely to be accurate to within a few hundred feet: for planes that's usually good enough to avoid hitting a mountain, as long as you've got enough of a buffer in your flight pattern, but we're still talking about an uncertainty of several percent, especially for smaller heights. Conceptually, what you're asking about is the correction between density altitude, pressure altitude, and actual altitude: technically feasible, as the density of air is related to the humidity and temperature (see Density of air for calculation) and air pressure is closely related to density. That density of air article has information on how humidity and temperature are used in calculating altitude. --Jayron32 12:56, 21 August 2012 (UTC)

The International Standard Atmosphere and the American Standard Atmosphere both assume the atmosphere consists of dry air so they won't be of any help if you want to use relative humidity to help fix an altitude. Dolphin (t) 13:14, 21 August 2012 (UTC)

I think I'm just going to throw out the temp and RH readings - looking more into how this is being used, I'm basically trying to simulate the output of a Kft altitude sensor that works entirely on pressure. Since the output I'm trying to duplicate doesn't care about temp and humidity, neither do I. I'll look for references on pressure to altitude, but if I don't find anything useful I'll take a stab at reversing the piecewise formula in Barometric formula. 209.131.76.183 (talk) 13:20, 21 August 2012 (UTC)

Mass of Thought

When I learn something new or remember an event, the information is stored in my brain. Does that information have mass?165.212.189.187 (talk) 13:38, 21 August 2012 (UTC)

Your body as a whole will slightly lose mass when forming a thought or memory, as it takes work to do so. Not sure about your brain specifically, though. Goodbye Galaxy (talk) 13:58, 21 August 2012 (UTC)

Reminds me of this Dilbert strip. AndrewWTaylor (talk) 15:04, 21 August 2012 (UTC)

There is a physical component of memory (see Memory#Cognitive_neuroscience_of_memory), but you aren't adding new mass when you learn new things, I don't think. The physical basis of memory — how you get from an experience to an encoded set of neurons — is still a very nascent field of study, as I understand it. There's no doubt there's a physical basis, but it's unclear to me whether talking about that in terms of mass makes sense, except in the obvious sense that all things to do with your brain do have physical mass. The way I picture it, which is not especially scientific (and is a hash derived from various sources, particularly Antonio Damasio) is that memory is more like a rattling of electrical charges through an existing structure, and the more you do certain things, the stronger certain pathways get. So you might imagine the brain as a cluster of special wire where the more you use them, the easier they become to use. The wires themselves are not added or moved — it's solid state, more or less — and what you're doing is making some pathways become more used than others. "Used" here means the sending of electrical/chemical signals through them. Or something like that. Perhaps others will have better ways to explain such a thing. --Mr.98 (talk) 15:13, 21 August 2012 (UTC)

OK, well does information in general have mass? I am thinking more along the lines of the information paradox of black holes argument.165.212.189.187 (talk) 15:34, 21 August 2012 (UTC)

As far as I know, from the age of three (?) we lose nerves every single day of our lives, so the brain should get lighter instead of heavier. Information is not stored in the brain as a physical entity, it is more like a connection. "The information is stored in my brain" is basically not correct. "The information can be recreated by my brain" would be a better way of phrasing this. Lova Falk talk 16:01, 21 August 2012 (UTC)

A connection is a physical entity. (It is not a non-physical entity.) --Mr.98 (talk) 16:09, 21 August 2012 (UTC)

Information is not a physical thing — it is better thought of as an event. It often is instantiated as a thing, but that is not its true nature. Consider a simple situation: I am signaling to you that I have arrived at my destination by flashing a laser at you. I've transmitted a bit of information. You might say, "well, you did shoot photons at me, and those are things." Indeed! (And note that we have there used massless things.) But if there had been an uninterrupted stream of photons, and I stopped them, now I'm signaling you with a lack of a thing. Thinking of information as a "thing" is just misleading — what matters is not whether a thing has been sent to you, or connected in your brain, or whatnot. What matters is the event. (Whether the event has meaning is a completely separate question!) Information theory is a nice place to start, but I warn you, it can get heavy sledding pretty quickly, because the technical definition of information (which matters if you are talking about black holes and things) is not the colloquial definition (i.e. semantic or conceptual information). --Mr.98 (talk) 16:07, 21 August 2012 (UTC)

Ok, I did check it out - double black diamonds! Thanks but wouldn't you have to preempt the "lack of thing to communicate" with a bunch of information communication to define what the lack of thing would actually communicate? So a connection is physical. Say the brain only uses 10% of its actual capacity, if it then was using 50% would that mean more connections...more mass than the 10% brain?165.212.189.187 (talk) 16:51, 21 August 2012 (UTC)

Bekenstein bound#Human brain gives a limit, though not one presumed to be of any practical relevance. Wnt (talk) 17:35, 21 August 2012 (UTC)

I think the existence of the Bekenstein bound implies that entropy has some kind of gravitational effect, but I don't know what the mechanism of that would be. It may be an open question. The thing about only using 10% of the brain isn't true—see ten percent of brain myth. -- BenRG (talk) 20:29, 21 August 2012 (UTC)

The type of information discussed in information theory (or when thinking about black holes) does not require consciousness to communicate. It just means "sequences of events other than pure entropy," or something like that — an opposite of randomness, a form of order. It has no inherent mass. --Mr.98 (talk) 22:55, 21 August 2012 (UTC)

Pure entropy and randomness are opposite of information??165.212.189.187 (talk) 20:12, 22 August 2012 (UTC)

No, I think information, randomness and entropy are basically the same. There are subtle philosophical differences but the mathematics is the same. They are all log (1/p) where p is a probability, or equivalently log N where N is a count of equiprobable states. -- BenRG (talk) 23:57, 23 August 2012 (UTC)

What about this lizard

This photo was taken in Artemisa (Cuba) here these lizards are very ordinary, but I can’t find anyone that tell me it scientific name http://en.wikipedia.org/wiki/File:Brown_lizard.jpg — Preceding unsigned comment added by Iskander HFC (talk • contribs) 14:35, 21 August 2012 (UTC)

The Cuban brown curly-tailed lizard, Leiocephalus cubensis -- OBSIDIAN†SOUL 15:01, 21 August 2012 (UTC)

(Chinese) Vegetable Identification

Can anyone identify this vegetable? It's common in Chinese grocery stores. Here's another photo.

Thanks! 2601:8:500:1B:8DFC:C408:2A71:54C0 (talk) 15:45, 21 August 2012 (UTC)pebble

Looks like Bok Choy, known in the west as "cabbage". --Jayron32 15:52, 21 August 2012 (UTC)

(Doh never quite quick enough!!) It's usually called 'Pak Choi' in my local supermarket but seems to have a variety of names. The wikipedia Article Chinese cabbage is what comes up when you search pak choi in Wikipedia but the images don't seem to match with what I'd call Pak Choi..however if you do a google image search you'll find loads of pictures like yours. ny156uk (talk) 15:54, 21 August 2012 (UTC)

We call it Pechay, and I grew up believing it was an English word.-- OBSIDIAN†SOUL 16:09, 21 August 2012 (UTC)

See wikt:pak choi and wikt:白. Wnt (talk) 17:46, 21 August 2012 (UTC)

That's funny. Many years ago I stopped in Angeles City on the way to Mount Pinatubo and saw curly/twister fries for the first time in my life. For years I believed they were indigenous. Perhaps they were. I never checked. Sean.hoyland - talk 18:08, 21 August 2012 (UTC)

Hah. And I also thought Goldilocks Bakeshop was an American company (I mean jeez, the girl was blonde). :P -- OBSIDIAN†SOUL 18:16, 21 August 2012 (UTC)

Marvelous. Sean.hoyland - talk 18:21, 21 August 2012 (UTC)

Radius of the universe

Ian Stewart's Concepts of Modern Mathematics contains the paragraph:

A certain theoretical physicist secured himself a mighty reputation on the basis of his deductions, on very general mathematical grounds, of a formula for the radius of the universe. It was a very impressive formula, liberally spattered with es, cs, hs and a few πs and √s for good measure. Being a theoretician, he never bothered to work it out numerically. It was several years before anybody had enough curiosity to substitute the numbers in it and work out the answer. Ten Centimeters.

Can someone tell me the name of the physicist and the formula? Thanks---Shahab (talk) 16:41, 21 August 2012 (UTC)

It may very well be that this is merely a humorous anecdote (or, in common English, a "joke"), and is not intended to be a scrupulously correct historical assessment of an actual event. That is, it is meant to be illustrative of a common error in theoretical physics (that it exists in the abstract, without an attempt to provide actual experimentation or numbers), and not meant to be an actual historical example. In other words, it sounds like the kind of thing that a theoretical physicist would do (propose a formula and then not bother to check it). The actual size of the Universe (as a scientific fact) is discussed in the Wikipedia article and section Universe#Size.2C_age.2C_contents.2C_structure.2C_and_laws and is more fully fleshed out in articles linked from there. Historically, the physicist most commonly associated with our current understanding of the Universe and its actual size (or lack thereof) is Edwin Hubble, though I seriously doubt that he is the source of the above anecdote. Or indeed, that anyone may be. --Jayron32 16:52, 21 August 2012 (UTC)

I've never heard this story before and it doesn't sound real. It sounds like a Hollywood hack writer's idea of theoretical physics. I tried googling and found only the book itself and a similar thread on physicsforums.com which reached no conclusion.

There are cases of famous physicists making mistakes which went undetected for long periods of time, such as John von Neumann's hidden-variable proof of 1932 which was called into question 34 years later by J.S. Bell. I see the article mentions a 2010 paper claiming that von Neumann was right after all, but if he's right it means Bell's error wasn't discovered for 44 years, so this is still a good example. :-) -- BenRG (talk) 18:46, 21 August 2012 (UTC)

I can only come up with three things that sound similar to that story, and none of them is a very good match. One is the radius of Einstein's static universe. That's not 10 cm, it's actually 10¹⁰ cm; but it's easy to see how that might be misinterpreted after several retellings to become 10 cm. The second is an estimate of the size of our observable universe at the end of inflation. Unfortunately, it's not a first-principles theoretical calculation brimming with e's, c's, and h-bars; and as far as I know it remains a reasonable estimate. The third and last candidate is a fine-tuning in which you look at the properties of "likely" universes and find that most of them are uninteresting. Either they recollapse too quickly, or they spread out too quickly, and you don't get multiple generations of stars as we need to have an interesting universe containing interesting people like us. You sometimes see estimates for the lifetime or size of a typical, "boring" universe. The entire point is that this sort of likely universe is obviously very different from the one we live in; so the part about nobody bothering to plug in the numbers doesn't work. I suspect the story has a kernel of truth to it but has been through a few rounds of telephone in which the details are changed for the benefit of the punchline. --Amble (talk) 00:42, 24 August 2012 (UTC)

Multiple Big Bangs

Could more than one Big Bang have happened at the same time as ours? I realize that our concept of space doesn't apply to before then, but could a non-interacting bang have happened in the same "locaction", such that we can't detect it or that we can only see effects like dark matter or energy, but in themselves could house a perfectly viable universe, one where ours is the mysterious missing matter? Mingmingla (talk) 17:12, 21 August 2012 (UTC)

No, I think this doesn't make sense. Dark matter and dark energy occupy the same spacetime as us, and one spacetime continuum means one big bang by any reasonable definition. There is a notion of particles that interact with each other but not at all (except gravitationally) with the particles we're made of, making them undetectable by anything other than dark-matter-like effects. This is sometimes called shadow matter, although that article seems to be about something slightly different. -- BenRG (talk) 18:54, 21 August 2012 (UTC)

Yeah, what's the difference between there being multiple big bangs at the same place and time, and there being one big bang that included particles that don't interact with ours? 203.27.72.5 (talk) 21:55, 21 August 2012 (UTC)

In any case simultaneity is relative. Plasmic Physics (talk) 23:18, 21 August 2012 (UTC)

Simultaneity is not relative when the position is the same. Someguy1221 (talk) 23:44, 21 August 2012 (UTC)

It is the velocities are different. If you imagine a neutron moving towards you at 0.5c and a neutrino moving away from you at 0.5c on a direct collision path, and you see both the neutron undergo beta deacay and the particles collide at the same time, a different observer who was perpendicular to the flight paths of the two particles would have observed them in a different order. 203.27.72.5 (talk) 00:29, 22 August 2012 (UTC)

No, they really don't. If two events occupy the same position in spacetime, they can only ever be seen as simultaneous. It's a trivial reduction of the basic example given in Relativity of simultaneity in which the length of the train is 0. Someguy1221 (talk) 00:41, 22 August 2012 (UTC)

But the Big Bang does not occur in spacetime, spacetime is a result of the Big Bang - the Big Bang is not located at any position. Plasmic Physics (talk) 01:38, 22 August 2012 (UTC)

Well, yes :) I was just addressing the general point about simultaneity. Someguy1221 (talk) 01:46, 22 August 2012 (UTC)

Wait a minute, did I just void my own statment - "at the same time" does not make sense without the crucial factor of time? Plasmic Physics (talk) 06:35, 22 August 2012 (UTC)

Castleton Botanical Gardens

This garden or gardens are mentioned in several Wikipedia articles, including Jamaica and George Samuel Jenman, and Google gives several results, but the problem is that there are variations on the name, sometimes two in the same article. So, which of the following six variations is the actual name of the garden?

• Castleton Garden
• Castleton Gardens
• Castleton Botanic Garden
• Castleton Botanic Gardens
• Castleton Botanical Garden
• Castleton Botanical Gardens

Once I have the formal name, I can make it consistent within English Wikipedia.

The nearest that I could find to an official webpage is The Jamaican Ministry of Agriculture and Fisheries Public Parks Department, which uses "Castleton Botanical Garden" in its header, although just to confuse matters it calls it "Castelton Gardens" in the following text. Alansplodge (talk) 19:36, 21 August 2012 (UTC)

Question about oral sex

please seek competent medical advice
The following discussion has been closed. Please do not modify it.
Does the eating of semen affect your health in any way? Please answer as soon as possible, I've read that it causes cancer and I've been doing it for a while and it's ruined it all for me, I'm afraid of it now. — Preceding unsigned comment added by Alabamaboy1992 (talk • contribs) 20:06, 21 August 2012 (UTC) Sorry, but we can't offer medical advice on the Reference Desk. StuRat (talk) 20:25, 21 August 2012 (UTC) No, we can't. μηδείς (talk) 20:35, 21 August 2012 (UTC) He ain't asking for advice. He asks if there are effects in general, not what he has to do now. I know this is a pretty weird question to see, but try to read it first--R8R Gtrs (talk) 20:39, 21 August 2012 (UTC) The question uses the phrase "affect your health" - thus it is a medical question. Case closed. Roger (talk) 20:45, 21 August 2012 (UTC) And...? I could also ask "How does drinking arsenic affect your health? I've heard people used to do it for cosmetic reasons." It's a general sort of "your" and we can point to the arsenic article and give info about the past uses. Dismas|(talk) 20:49, 21 August 2012 (UTC) I don't get it. I saw recently a question where a man was asking how having a cold gets feel weak. And no single person found it inappropriate. I'm also pretty sure that the arsenic question, if asked, should be replied. I'd prefer an answer like arsenic destroys the stomach cells by disintegrating an important lipid (for example, I dont really know how arsenic poisoning works), which results in severe pains, internal bleedings, and death (made up consequences). So do I get it right? You can't ask "how does walking if shorts and a shirt in winter affect one's health", but rather when the effect is known, "how so I feel weak having a cold"? Do you feel the difference between medical questions and medical advice? Advice means you suggest something to do... The individual doesn't want that. It's that they are asking about their own case that makes it medical advice, as in "I've been doing it for a while and it's ruined it all for me, I'm afraid of it now". StuRat (talk) 21:20, 21 August 2012 (UTC) Huh. That's a good point. However, I am still sure that texting a list of possible consequences without giving emotions would not qualify as advice, and that things outside the question don't matter-- essentially, that's still the same question. Maybe I misunderstand the word advice? However, you may be right in that the man could be better sent to the doctor... Tl;dr Still don't agree somehow/Won't argue further (doing the "wrong" things to achieve the ultimate right one is acceptable to me, if that's the case) What you probably read in the news a couple years ago was that HPV, which can be transferred through oral sex, is an increasing cause of oral cancer [3](more than smoking, perhaps). There is no advice on course of action intended to be conveyed by this statement, consult a medical professional, blah blah blah, etc. Buddy431 (talk) 21:40, 21 August 2012 (UTC)

This is a very general question, and we would be remiss if we did not direct readers to Oral sex#Health risks and other studies for some useful public health information. Wnt (talk) 12:34, 22 August 2012 (UTC)