Wikipedia:Reference desk/Archives/Science/2013 April 12

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

April 12

Low mass white dwarf actually currently exist

Since the article said white dwarf can be 0.17, do the white dwarf dwarf being 0.17 actually exist currently, or is it just the estimation of the stars did not yet come off the main sequence. Is this true alot of white dwarf are binary stars, can 0.5 solar mass white dwarfs? is it more common for white dwarf to be single star system, or binary star system? Is white dwarf all the exact same size on single star system/non-binary star ssytem? or the Solar mass determined by white dwarf has to determine exactly how big the white dwarf has to be?--69.226.42.134 (talk) 00:36, 12 April 2013 (UTC)

I struggle to see how a very small white dwarf (such of 0.17 solar masses) could form other than from a small red dwarf collapsing. Red dwarf stars live for a very long time, so none of them are dead yet. That would suggest there are no very small white dwarf stars. A lot of stars are in binary systems and they will generally remain in those systems when they die, so yes it is true that a lot of white dwarfs are in binary systems - I don't know if it is more than half, though. The size of a white dwarf is determined by the size of the star that formed it. In a binary system, there might be some transfer of matter between the stars that can change things. In a non-binary system, there obviously won't be. Does that answer most of your questions? I found them a little hard to understand... --Tango (talk) 11:43, 12 April 2013 (UTC)

Stars loose a substantial fraction of their original mass when they go through the late stage of red giant/Asymptotic giant branch and planetary nebula stage, so the white dwarf may end up much lighter than the original star. With that said, I have to say I don't really know what the lightest white dwarfs masses are. Dauto (talk) 19:09, 12 April 2013 (UTC)

See SDSS_J0106-1000. Ruslik_Zero 19:19, 12 April 2013 (UTC)

Fascinating case! I'm trying to picture what it will look like as they get very close together. I suppose Roche lobes can't actually have condensed matter going all the way to the center because it should be under zero pressure there. I suppose if humanity somehow doesn't self-annihilate, the more lunatic descendants of our race will dive through that strait for excitement. When the stars do start to fuse ... I suppose they'll still be rotating too fast to have enough pressure in the center for helium fusion, but it would start somewhere under the combined pole?Wnt (talk) 22:13, 13 April 2013 (UTC)

Bird evolution

Are the falcons, parrots, and sparrows really the closest relatives of one another, as people say? If so, who evolved from whom in this taxonomy? And also, if the falcons and the passerines are so closely related, which of the passerines are the most closely related to the falcons? (I'm guessing it would be the swallows, based on purely morphological info, but I can't be sure). Oh, and are the whippoorwills more closely related to the swifts, or to the owls? 24.23.196.85 (talk) 05:50, 12 April 2013 (UTC)

None of those groups evolved from another of them. Their most recent common ancestor was a member of neoaves but not of any of those groups (according to our articles). All falconiformes are equally closely related to all passerines. Regardless of which falcon and which passerine you pick, you get the same ancestral species as their most recent common ancestor. And according to our articles, whippoorwills are more closely related to swifts than to owls. Looie496 (talk) 06:43, 12 April 2013 (UTC)

(EC) You may be thinking of discussion surrounding some recent studies like [1] [2] [3] [4]. You should be able to read both studies (the former may require free registration) and although they may be a little difficult for someone without a biological background to properly understand, you should get some idea and should also be able to view the various trees shown and seek help here to understand the parts which are confusing. The 2008 study (first 2 links) in particular was and is I believe regarded as fairly significant, you should be able to find a fair amount of discussion of it in blogs and other such sources, although looking for the better ones may be difficult, I think [5] is okay. As mentioned in our article Evolution of birds#Classification of modern species, this is still an area of some flux (as with quite a lot of taxonomy, particularly given the increasing ease of genomic analysis) and the 2008 study is obviously only about 5 years old although I don't know specifically how well the relationship between the species you mention is supported. I would note statements like 'who evolved from whom in this taxonomy' should generally be avoided when talking about extant species as neither extant species is going to be the same as the ancestral species. Similarly for statements like 'which of the passerines are the most closely related to the falcons' as most likely they all have the same most recent ancestral species. Nil Einne (talk) 06:51, 12 April 2013 (UTC)

Thanks! Maybe I should have put the question about "who evolved from whom" another way: which of the three orders (falcons, parrots and passerines) is the closest to their common ancestor, and which is the most distant? 24.23.196.85 (talk) 01:06, 13 April 2013 (UTC)

Most evolutionary biologists would consider them all to be equally distant from the common ancestor. That's because the usual way of measuring distance is time since the split. There are other possible measures, for example disparity between genomes (which can vary because there is some variability in rates of mutation). Even for that you would probably find that they are all at nearly the same distance, and it would be quite difficult to find out which is closest. Looie496 (talk) 02:19, 13 April 2013 (UTC)

Right, I was asking about genetic distance from the common ancestor. But I wouldn't be surprised if the answer comes out to be "Insufficient Data". Thanks for the info! 24.23.196.85 (talk) 03:29, 14 April 2013 (UTC)

Sediba's hands.

Can anyone figure out what's going on with Sediba's hands in the skeleton on the right, here? μηδείς (talk) 10:00, 12 April 2013 (UTC)

Have you mis-read the caption? H sediba is in the middle. The one on the right is a chimp. Rojomoke (talk) 12:13, 12 April 2013 (UTC)

I assumed the caption above was for the picture above--but please look at the hands (and the snout) and tell me if that looks like any great ape you've ever seen. The thing has effing flippers. Or am I missing something? μηδείς (talk) 12:59, 12 April 2013 (UTC)

There seem to be a few fingers missing. Dauto (talk) 14:32, 12 April 2013 (UTC)

It might help to look at http://www.boneclones.com/KO-303.htm. Looie496 (talk) 17:10, 12 April 2013 (UTC)

According to Looie's link the shape looks right, It still seems quite odd that the hand is the length of the femur. μηδείς (talk) 17:15, 12 April 2013 (UTC)

A Google search provides images of chimp skeletons (also orangutans and gibbons). The hands in OP's picture are in the foreground and the phalanges of the left hand are splayed, which makes the hands appear larger, but the relative size does seem to be typical of a chimppanzee. The snout length and nasal opening do appear different than in other images of chimpanzee skeletons, but these are the only images I've seen recently, so I'm far from expert.--Wikimedes (talk) 19:39, 12 April 2013 (UTC)

So in other words the chimp is standing with his hands toward the camera, like this? I suppose that would explain the otherwise apparently freakish proportions. μηδείς (talk) 19:57, 12 April 2013 (UTC)

Motion of electrons

What type of motion of electrons around the nucleus? It is circular, periodic, uniform, non-uniform or other motion? Scientist456 (talk) 12:27, 12 April 2013 (UTC)

No one knows, I asked a similiar question here some time ago. Plasmic Physics (talk) 12:36, 12 April 2013 (UTC)

I suggested two types of motion, which are both wrong (now I know): random teleportation; and they exist everywhere at one in the form of an electronic fog, the mass and charge density profile of which is described by the schrodinger equation. Plasmic Physics (talk) 12:40, 12 April 2013 (UTC)

Electrons don't move in a classical motion. Indeed, they are not classical particles. Their distribution probability is governed by quantum physics. Some simplified models assume discrete circular orbits with additional constraints. See Bohr model, Matter wave and Pauli exclusion principle. --Stephan Schulz (talk) 12:46, 12 April 2013 (UTC)

So, basically they slosh? μηδείς (talk) 13:00, 12 April 2013 (UTC)

... and sometimes they tunnel. See atomic orbital for more information. Gandalf61 (talk) 13:10, 12 April 2013 (UTC)

Periodicity figures strongly in quantum mechanical treatments of particle motion (basically to prevent particles from interfering with themselves), see for example particle in a box. Atomic_orbital#Orbitals_table has drawings of the shapes of probability distributions of single electrons of different energy levels orbiting a nucleus.--Wikimedes (talk) 19:13, 12 April 2013 (UTC)

From my limited knowledge- the electrons are in various shaped shells which are a probability density function. There is something called the measurement problem [[6]] which prevents the particle from behaving in the classical sense. — Preceding unsigned comment added by Ap-uk (talk • contribs) 23:32, 13 April 2013 (UTC)

That considers where they move, not how. Plasmic Physics (talk) 13:12, 15 April 2013 (UTC)

Invasive species

Humans have invaded the entire planet, each and every continent, oceans, destroying all ecosystems and making other species extinct. They why humans are not considered invasive species? --Yoglti (talk) 16:53, 12 April 2013 (UTC)

Who says that humans are not considered invasive species? Looie496 (talk) 17:12, 12 April 2013 (UTC)

See Gaia hypothesis. --TammyMoet (talk) 18:27, 12 April 2013 (UTC)

the idea of invasive species is a matter of point of view, really. it's not like the biosphere of the earth is defined or has a defined goal. one species piggy backs on another and ends up in a new area and does well. doesn't matter if it's in the bilge of a ship or the large intestine of a dinosaur. but as far as being responsible for extinctions, we are definitely number one, i would guess Gzuckier (talk) 20:01, 12 April 2013 (UTC)

Why Wikipedia article Invasive species does not list humans? --Yoglti (talk) 09:43, 13 April 2013 (UTC)

Because we're too arrogant? It's not really the point of the article, we don't really compete in any ecological niche any more, we're "out of the race" so to speak. Vespine (talk) 23:04, 14 April 2013 (UTC)

Probably because almost every definition of the term "invasive species" is contingent upon some activity, presence, and demarkation by and of humans. For the most part, invasive species wouldn't be invading without humans. ~ Amory (u • t • c) 17:29, 15 April 2013 (UTC)

Limits of knowledge

If knowledge, memories, thoughts, are just connections made in our brains, does that mean that knowlede has limits? I mean its possible that we might not even comprehend all there is to know about the universe?203.112.82.128 (talk) 17:52, 12 April 2013 (UTC)

Yes, you can only store a finite amount of information in your brain. You can't even know the exact state of your own brain, because that would require at least the full brain capacity while a lot of that is already in use to perform essential functions. Count Iblis (talk) 17:56, 12 April 2013 (UTC)

Haldane's Law (excuse the archaic language): "The universe is not only queerer than we imagine, it is queerer than we can imagine" --TammyMoet (talk) 18:26, 12 April 2013 (UTC)

yeah, after studying a lot of philosophical basics lately (The Great Courses, better than my college humanities requirement) i've come to doubt not only that humanity is capable of understanding the underlying reality of the universe, but that there even is an underlying reality; as well as that humanity is capable of understanding the functions of "mind" as distinct from brain. Gzuckier (talk) 20:07, 12 April 2013 (UTC)

However, with the invention of writing, it became possible to store knowledge outside the brain. And, with the internet, we can now potentially quickly access all knowledge we have accumulated. Wikipedia, of course, plays an important role in all of this.

I like to think of knowledge like a program and data. The data can be stored outside the brain, with the brain just holding the program to use that knowledge. For example, say I want to determine the volume of a sphere. I access the data externally, to get the formula to calculate it. The formula is V = 4πr³/3. Now I use the program in my brain to determine that r means the radius and π means ≈3.14159 (or I look that up, if I don't know it already). I then use the program in my brain to tell me how to multiply, divide, and cube numbers, probably using a calculator. This is a very simple example, but we can potential solve much more complex problems in this manner. StuRat (talk) 20:21, 12 April 2013 (UTC)

I apologize but i think im looking for a different answer and its my fault because i didnt formulate my question well. What im trying to get into is, say a coin, there is only heads and tails, so there is just two outcome if you flip a coin, now go to our brains, there is just limited number of combination of connections in our brain right? Now my question is, given that the method on how we understand things are just one combinations of our connections in our brains, is it possible that there are certain data in our universe that we will never understand simply because its something that needs to be a set of connection that our brain is not capable of doing? for example, back to the coin, is there a data that niether heads nor tails can understand? Im not a native english speaker so please try to understand and thanks in advance. 203.112.82.1 (talk) 22:01, 12 April 2013 (UTC)

but that's the question; how is information stored in the brain? it's definitely not the way it is in computers. to me it seems to be more diffuse; i.e., you can forget what your grandmother looked like, but you won't forget that you had a grandmother, or that your grandfather was married, or that your mother had a mother, or what a grandmother is in general. it's like every concept/meme has a bunch of loose ends that tangle up with the loose ends of other concepts, somehow, in such a way that much of the structure assembles itself from what it connects to. as if you have a grandmother-shaped region in your model of the world, and even if you've forgotten or never had the memory of your senses in reference to your grandmother to fill in the hole, that grandmother-region still must exist and be referred to as grandmother by the rest of your mental world. so, what are the limitation of something like that in terms of finite number of neurons and synapses? well, you certainly can't know everything about the universe in perfect detail, i.e. the state of every subatomic particle, but that might be as much an effect of the finite amount of time you have to investigate than of your storage. Gzuckier (talk) 01:14, 13 April 2013 (UTC)

• Tangentially related to this discussion are concepts like the Bekenstein bound and Bremermann's limit. The math and physics there is pretty dense, but the concept is sound: there has to be an upper limit to the amount of information we can store about anything, and how well we can retrieve it. We can't know the entire universe, because to store information about the entire universe would require an entity at least as large as the universe and separate from it. The entire field which deals with quantifying information, including its storage and retrieval, is known as Information theory, which in part deals with the very question of how much information can be stored in a given medium. For example, the theoretical maximum amount of information stored in your brain is constrained by the number of cells and synapses in your brain. Now, this theoretical limit is probably orders of magnitude more than the functional limit, but it's a starting point, and indeed, is a subject which is well studied and explored, if you have the time to research it and the ability to weed through some fairly arcane mathematics. --Jayron32 05:30, 13 April 2013 (UTC)

• But that's why we have models. A simplified model allows you to store most of the important information about an object in much less space. Take the blueprints for a building. They may not note where every nail is, but you don't normally need to know that, and, if you need that level of info, you can go and look for the nails at that time. StuRat (talk) 17:59, 14 April 2013 (UTC)

It is already clear to me that there is a limit in how much info our brain can store, im more interested in what is the limit of what our brains can understand. In theory, if i study hard enough, i would be able to understand special relativity , but is there any concepts out there that our brains are not wired to understand? I mean of course if the answer is yes, we wont know the things we were not able to know, im just curios if there is any research or concepts that tackles this subject. I dont know if gzuckier already answered this, if so, can you please explain more 203.112.82.128 (talk) 17:53, 13 April 2013 (UTC)

I'm not sure I grok what you mean by "understand". You say "are there any concepts out there that our brains are not wired to understand". Concepts are all human-created things, so theoretically no, there is no concept which cannot be understood by any human. In order to be a concept, it has to have been conceived by somebody, which means that at least one person understands it. Now, colloquially, there are certain famous "concepts" which have been (jokingly or a bit tongue-in-cheek) said to have been incomprehensible. Lord Palmerston famously said of the Schleswig-Holstein Question that "Only three people...have ever really understood the Schleswig-Holstein business—the Prince Consort, who is dead—a German professor, who has gone mad—and I, who have forgotten all about it." and Richard Feynman once famously said of Energy, "It is important to realize that in physics today, we have no knowledge what energy is." Now, that doesn't mean that these problems are entirely incomprehensible (many historians have extensively studied the Schleswig-Holstein question, for example, and some I am sure have a good handle on it, and energy is something which many physicists study extensively, Feynman's quote is merely a negative assertion of the Dunning–Kruger effect, which notes that the deeper physicists get into energy, the harder it is to define it in as simple terms as, say, a high school physics text does). But fundamentally, no, there is no concept which is entirely incomprehensible to any humans insofar as any coherent concept is a human-created thing in the first place. If you really want to get deep into this, do some reading in the branch of philosophy called Epistemology. --Jayron32 03:30, 14 April 2013 (UTC)

When I say "understand" I mean when you are introduced to a data, your brain rearrange its connections so that you would comprehend the data in front of you. and since brain is just a finite thing, I assume there is only finite ways of rearranging those connections, meaning there's a limit of what we can "understand", I dont think im asking about the philosophy of it but simply the physical limits of our brains. 203.112.82.1 (talk) 16:03, 14 April 2013 (UTC)

In this sense, you can understand everything. The brain is capabable of universal computation (the limits only being the amount of data it can process). At various levels, if there is anything to understand about some natural phenomena, you can formulate it in terms of simple equations, which the brain can easily handle. If it's not a matter of something you can formulate using a few bits of information, then you cannot say that there is a clear cut explanation for the observed phenomena, as it would depend on a large number of variables. So, there would then be nothing to explain. Count Iblis (talk) 16:18, 14 April 2013 (UTC)

You seem to have ignored my comment on our ability to store information externally to our brain. To use a computer analogy, the RAM is the where the "programs/intelligence" is normally stored, but the data is largely on the hard drive or other external media. Similarly, humans only need to store the intelligence in their brains, and can access the data from other sources, like Wikipedia. StuRat (talk) 17:54, 14 April 2013 (UTC)

Oh no, I understand your answer that knowledge can be stored outside of our brains, but I just thought that it is not what I'm asking about. To use your computer analogy, what i was asking is if there is a file type that my computer cannot read, for example the brain is capable of reading .jpg or .gif files, but is there a .wiki of .xyz that we will never comprehend? 203.112.82.1 (talk) 20:37, 14 April 2013 (UTC)

Well, you can have a file too large to store the entire thing in RAM at once. The computer then uses paging space or other methods to store parts of it externally. It works out that to solve most problems, you only need to keep a small portion of the data in active memory at any time (although it certainly is faster if you can keep it all there). StuRat (talk) 13:36, 15 April 2013 (UTC)

Ok, when you say "file too large to store", I assumed your answer is still regarding the limit of data our brain can store, which is not why im asking, or maybe i just didnt understand the answer.203.112.82.128 (talk) 16:02, 15 April 2013 (UTC)

Stud finders

Looking at the reviews of stud finders on Amazon, all of them have mixed reactions. Some people say they work as they should and others say they don't. I'd like a stud finder but would like one on which I can rely. Are some people just using them wrongly? Some people say they're inconsistent. --2.97.27.107 (talk) 17:54, 12 April 2013 (UTC)

They are many types of walls and a few types of stud finders. Most work fairly well on modern drywall (plasterboard)-type walls. But on my old over-an-inch thick plaster/gravel/horsehair on metal lath walls, none ever work. Rmhermen (talk) 19:05, 12 April 2013 (UTC)

I've tried out maybe 4 or 5 different types over the years, both the magnetic (looks for nails) kind or the electronic (capacitance I assume) kind, not any of them worked any better than just pounding on the wall and listening for the change in sound. Gzuckier (talk) 20:09, 12 April 2013 (UTC)

Yeah, I think I'm just gonna knock on the wall. Thanks 2.97.27.107 (talk) 21:08, 12 April 2013 (UTC)

Drilling exploratory holes with a really thin drill bit is another strategy, the idea being that the holes are so tiny you can patch or cover them easily and they will never be noticed by most observers. HiLo48 (talk) 23:05, 12 April 2013 (UTC)

Studs are also spaced a standard distance apart, usually, so once you've found one, a ruler is usually helpful. In most houses, electrical outlets and switches are required to be in junction boxes which are bolted to a stud. In the United States, the standard is 16 inches center-to-center between studs. So, if you start at the wall switch, find the stud it is attached to, then measure off 16 inches, you should find another stud. And so on. --Jayron32 03:55, 13 April 2013 (UTC)

Maybe. 16" is a modern standard for exterior walls in many locations. But other walls (especially interior) may be 12", 16", 18", 19.2" or 24". Not to mention doubled studs, ones moved over for pipe runs, bizarre window framing. And it depends on local codes for climate, hurricanes, type of stud, etc. Construction practices have changed greatly even in recent years. Rmhermen (talk) 16:16, 13 April 2013 (UTC)

Most stud finders I think, work well for most people. The problem may be in part that complaints are, as the OP opinions, by some people who don't know how to use them properly and impart because some walls (as found by editor Rmhermen above) defeat the capabilities of cheap stud finders. Borrow a cheap stud finder to see if it suits your walls – if so good – answer obvious. If not borrow a professional stud finder. If you find that better -then buy one. Don't know what part of the world your in but a professional quality SUB-SCANNER M12 is not expensive when you consider how much it would cost you to get a professional trades person in to do the job. These detectors have the necessary discrimination to cope with most walls.Aspro (talk) 19:31, 13 April 2013 (UTC)

biology

Is there possibility of multiple nipples in one brest of a human female ?If so then what is the reason? — Preceding unsigned comment added by Titunsam (talk • contribs) 18:25, 12 April 2013 (UTC)

The article you want is probably supernumerary nipples. Rmhermen (talk) 18:53, 12 April 2013 (UTC)

Um, witchcraft. μηδείς (talk) 19:58, 12 April 2013 (UTC)

Francisco Scaramanga. Though i don't think Christoper Lee is female. --Jayron32 02:32, 13 April 2013 (UTC)

It is not limited to females (or humans for that matter) Roger (Dodger67) (talk) 12:03, 13 April 2013 (UTC)

the real star wars universe in 2014?

I want the real Star Wars universe by next year please. Contact NASA. SmallSoldiers123 (talk) —Preceding undated comment added 21:39, 12 April 2013 (UTC)

Is there a question? But here is NASA's contact page. Cheers. --Wirbelwind(ヴィルヴェルヴィント) 22:06, 12 April 2013 (UTC)

Resolved