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Why is S2O32- impossible as a molecule? So far I've found its 3D structure is a very unstable zig-zag shape, but is there a better reason? THanks. EDIT: I am actually going from a Lewis drawing which I have written the formula for, unaware that there is actually a differently shaped molecule thiosulphate for the formula. I will try to describe it: the Oxygen and Sulfur form a chain, with oxygen on both ends. They are all covalently bonded on both side (obviously excluding the end atoms). The two electrons are added to both end oxygen to fill the outer level. 24.92.70.160 (talk) 03:32, 21 January 2011 (UTC)[reply]
What do you mean it is impossible? Have you read Thiosulfate? --Jayron32 04:01, 21 January 2011 (UTC)[reply]
To answer why your molecule doesn't work: the short answer is that the thiosulfate arrangement is most stable; your arrangement may end up with a very unbalanced formal charge distribution (and indicator of an unlikely structure) or it may have an unstable molecular orbital arangement. Incidentally, Molecular orbital theory has a much better predictive power for molecular structures than Lewis Theory does. The deal is, it is much more complex than Lewis theory, but it gets the "right" answer more times than Lewis theory; for example MOT correctly predicts that the oxygen molecule is a diradical, something impossible to draw in a Lewis structure and still maintain symmetry and a double bond. MOT is capable of describing a symetrical, doubly bonded, diradical oxygen which more closely matches the actual structure. --Jayron32 04:06, 21 January 2011 (UTC)[reply]
In general, sulfur is rather amenable to long chains S-S-S-S etc. (S8 for example: see allotropes of sulfur). But any attempt to do this with oxygen fails. Tetraoxygen almost but not quite has the potential to exist, and other forms of solid oxygen go a different path. I remember asking about this before and hearing something about the extra orbitals in the outer shells of sulfur coming into play, but I'm afraid I didn't quite understand how it worked then, so... Wnt (talk) 05:11, 21 January 2011 (UTC)[reply]
Another thing to consider is that 5-atom molecules tend to (almost) universally assume a Tetrahedral molecular geometry. If you've got 5 atoms to try to fit into a structure, start there. Early chemistry students have a hard time thinking "three dimensionally" so don't often see the symmetry and stability of that shape; and often what results is all sorts of strange arangements, either linear or cyclical in nature. Always start with one of the basic molecular geometries (180 degrees, 120 degrees, or 109.5 degrees) and only go on to more complex structures if those don't work. --Jayron32 05:31, 21 January 2011 (UTC)[reply]
The Ethiopian mountain Erta Ale is in the historical land of Punt at the fringes of ancient Egyptian influence. (see File:Egypt_NK_edit.svg) It superficially resembles a traditional notion of Mount Horeb. To me it would seem to make sense that Moses might have scouted the location before settling on the equally remote region to the east of the river Jordan as a place to which to withdraw. In modern times it is a continually active volcano, with a pool of lava that has been stable and accessible for the past hundred years. Which raises some questions in my mind...
Was Erta Ale similarly active near the end of the Eighteenth dynasty of Egypt a bit more than three millennia ago? Or could other volcanoes along the Rift Valley have been similar then?
Does the outgassing from a volcano like this create a usable reservoir of water to which a nomadic tribe might expect to come to drink? Is it reasonable that hammering into the rock could do something useful to release it if the level is low?
Suppose you have a thick rope and a large ceramic bucket. Is it possible to fill the bucket from a lava pool like that pictured, and pour it into a mold or work on while molten, in such a way to create tablets which could be presented as "inscribed by the finger of God" (and recognizably not by any method known to skilled craftsman of ancient Egypt)? Wnt (talk) 04:12, 21 January 2011 (UTC)[reply]
Except that it doesn't match other parts of the Exodus narrative. If other scholarly consensus is to be believed, the Crossing the Red Sea occurred at either the Gulf of Suez or "Lake Timsah", a freshwater body just to the north of the northern tip of the Gulf of Suez. The Stations of the Exodus lays out a pretty consistent route, and none of it ends up anywhere NEAR Ethiopia. Furthermore, the Biblical Mount Sinai (usually identified as identical to Horeb), while its location is unknown, is generally placed either in or near the Sinai proper. While many of the stations lack modern locales with certainty, Ezion-Geber is well attested to and it is also nowhere near Ethiopia. Exodus 19 makes it clear that it took 3 months to get to Mount Sinai. How they got from the Gulf of Suez to Ethiopia in 3 months is beyond me, especially as the only route takes them back through Egypt; probably not the best way to go. --Jayron32 04:36, 21 January 2011 (UTC)[reply]
(ec)I don't want to start a huge humanities detour - I doubt I would hold my own in a proper archaeological and biblical debate about this. Generally I'm going by the idea that Moses is described as going to Horeb in Exodus 3, then returning to Egypt [1] so (at least at the first mention it need not necessarily be en route. I don't know for sure that Mount Horeb is truly a place, or has some more general status (like "Air Force One", which is not a literal single aircraft). I was mostly giving the idea behind this as an explanation for the rather peculiar questions about Erta Ale. Wnt (talk) 04:51, 21 January 2011 (UTC)[reply]
Is this by any chance a Ron Wyatt-inspired question...? WikiDao☯ 04:49, 21 January 2011 (UTC)[reply]
No, never heard of him. I see he placed Mount Sinai in Saudi Arabia... in general, it's hard to prove any unconventional idea based on historical evidence, since the evidence necessarily points at the conventional interpretation. But it is all too easy to propose one. That's why I want to take this from the other end and say, if I were at Erta Ale, could I strike the rock and make water come out of cracks in the rock? Could I scoop up some lava and make some impressive looking non-carved words in stone tablets? And if so, then is Erta Ale the only such place, or are there others? Wnt (talk) 04:56, 21 January 2011 (UTC)[reply]
No I don't think you can make/find water that way (without God's help of course :) Water usually flows from springs that are below the water table, but a volcano rises above it. Plus water from a volcano is mixed with sulfur and other chemicals and is not drinkable (water is frequently mixed with lava and a steam explosion is a common cause of an eruption). Lava would make a very poor casting material. It has a very coarse texture, and would show shapes very poorly. Plus it doesn't match the description of the tablets which were extremely heavy (and lava rock is very light), and were sapphire blue. Ariel. (talk) 07:58, 21 January 2011 (UTC)[reply]
Where's the praline That quality (coarse and light) depends on the volcano, surely. Pumice is crumbly and floats, but obsidian is perfectly smooth and quite heavy, and basalt I think varies. 81.131.65.219 (talk) 17:38, 21 January 2011 (UTC)[reply]
Obsidian is smooth and heavy, yes, but it is essentially glass. For a quick comparison, take a chunk of glass and try chiselling something into it and let us know how you make out. :-) It makes outstanding points, but it's not something I would ever try to carve into with a metal implement. Matt Deres (talk) 18:00, 21 January 2011 (UTC)[reply]
Wnt is suggesting casting it, though - or casting dense basalt, judging by the below remarks. 81.131.65.219 (talk) 18:13, 21 January 2011 (UTC)[reply]
The difficulty in chiseling it is actually crucial to the plan. The point is, master stonemasons who build great obelisks as a matter of routine should have been able to look at the tablets and (unaware that lava is molten rock) declare that it is physically impossible for the hand of man to make them. Wnt (talk) 19:18, 21 January 2011 (UTC)[reply]
Check out the Portland Vase, though, an awesome piece of glassware made in a year somewhere between 5 and 25, the decorations done, I think, by chiseling. I also see in Ancient Egyptian technology#Glassworking that cast glass is a very old technique. So presumably a high-level craftsman would not be taken in, whereas a low-level craftsman could be convinced if you just made the tablets out of clay with a bit of sand thrown at it. I wonder whether investigative skeptics abounded, anyway. 81.131.65.219 (talk) 20:08, 21 January 2011 (UTC)[reply]
(ec/outdent)I know that the water begins mixed with chemicals, but if it emerges as a column of steam, there should be places nearby where it condenses as distilled water ... I think.
I found a rather convoluted explanation of why the tablets are said to be made out of sapphire online,[2] but compare "The LORD said to Moses, “Chisel out two stone tablets like the first ones..."[3] I'm not sure a blue color is strictly required. Now I know that obsidian can present a very smooth surface, and there are many such smooth lava flows. But a description of Ethiopian volcanoes mentions obsidian flows from some other volcanoes in the area, but describes Erta Ale as basaltic.[4] I don't know if a stone like tachylite (from rapidly cooled basaltic lava) would give a usable surface, but if it did, the stone is described as being very brittle, which seems consistent with the smashing of the tablets. Wnt (talk) 17:48, 21 January 2011 (UTC)[reply]
To go back to some of the original questions, this or a similar volcano is likely to have been active at the time. Obsidian is unlikely from the volcanoes of the northern Ethiopian rift, I would think, but basalt can certainly be pretty glassy. I wouldn't expect to find significant water on an active volcano in an arid environment (although I recall that things may have been different a few thousand years ago climatically). As to the rope and bucket - the bucket might survive, but the rope wouldn't, that molten lava is at 700°C minimum, never mind the protection that the people trying to get the lava out would need. Mikenorton (talk) 18:17, 21 January 2011 (UTC)[reply]
It sounds feasible to me but technically tricky, and would require Moses to hang around the volcano for a month or so secretly designing and manufacturing different kinds of buckets. 81.131.65.219 (talk) 18:36, 21 January 2011 (UTC)[reply]
Forty days and forty nights?[5] Admittedly, the rope is a clear vulnerability - though in the current caldera it looks like there is a cooled crust and fairly good airflow, reducing the direct and convective heating, and of course you can always soak it in water before lowering. Wnt (talk) 19:18, 21 January 2011 (UTC)[reply]
I figured rather than a bucket you'd want a long-handled ladle, which could also be used to manipulate the lava from a safe distance once it's hauled up, and tie the rope to that. Not sure whether the necessary length is within the bounds of practicality. The bowl of the ladle would be pivoting, like a bucket on a handle. 81.131.65.219 (talk) 19:56, 21 January 2011 (UTC)[reply]
Sorry, I was glossing over the bucket part because I figured they could work out something. But to give an example, take an amphora and suspend it by ropes through the handles and around the neck, and smash out a hole a little way up one side for the lava to flow into. Maybe tie a weight around the neck to help the bottom make it into the lava. Wnt (talk) 20:02, 21 January 2011 (UTC)[reply]
scroll down - you'll discover "medical terrorism" instead of "medical tourism". This has been edited on 20/1 (yesterday). —Preceding unsigned comment added by 132.72.226.107 (talk) 06:39, 21 January 2011 (UTC)[reply]
Already edited myself and changed it back to tourism. Only problem is that the links are still pointing to wrong articles.. This I cannot change. —Preceding unsigned comment added by 132.72.226.107 (talk) 07:19, 21 January 2011 (UTC)[reply]
This is the wrong place for this, but I checked history of the article and reverted it back to before the vandalism. But I don't understand what you mean by "links are still pointing to wrong articles" - can you explain? Ariel. (talk) 07:35, 21 January 2011 (UTC)[reply]
Ok, I'm not touching it again.. just tried to change it and you reverted my changes :-).
so just try to follow the links and see for yourself. If they point to the articles they claim to be pointing to, than everything is all right. check it.
btw, what is the right place for this? —Preceding unsigned comment added by 132.72.226.107 (talk) 07:38, 21 January 2011 (UTC)[reply]
Here: Wikipedia:Administrator intervention against vandalism to request a ban, but before going there the user needs to be warned (but he has been). Normally go here: Wikipedia:Abuse response. The links were not changed by the vandal - it looks like Haaretz changed their site. This is not uncommon. It would be great if you could search their site and find the new location of those articles. Don't just remove the references like you did, find the new url for them. Ariel. (talk) 07:51, 21 January 2011 (UTC)[reply]
10x for the help. About finding pro-Israeli articles at Haaretz site - yeah right.. why don't you have a go :-). Well, have a nice weekend. gotta go. —Preceding unsigned comment added by 132.72.226.107 (talk) 07:58, 21 January 2011 (UTC)[reply]
I'm not sure what you're referring to since no one else discussed pro-Israeli articles at Haaretz. I can't find any sign of the article on Haaretz but as Ariel has said, speaking generally it's hardly uncommon the articles disappear in site reorganisations or whatever. Some websites don't even bother to keep articles for that long trying to encourage subscriptions to archives etc. In any case, I doubt Haaretz removed the article because it was "pro-Israeli". It was on Haaretz at one stage as proven by this archive.org[6] archive which I added to the article. Nil Einne (talk) 09:47, 21 January 2011 (UTC)[reply]
I'm not sure if it's a scientific question or not; but I have a religious friend who says:"Science can't be trusted because it's always changing and scientists always make mistakes.".I do trust science, but is this some kind of faith? Is it a good reason not to trust science at all? do we have enough reasons to do so?--Sina-chemo (talk) 11:40, 21 January 2011 (UTC)[reply]
Without modern science, life expectancy would be far lower. Travel, communication, technology would not exist as they do. Without science, we would be living in the middle-ages. Science definitely makes mistakes, but the beauty of it is that science is free-form, and constantly updating itself, constantly challenging ideas in the search for truth. Your friend has been (struggling not to say brainwashed) given somebody else's opinion. Besides, I bet this "science hater", uses products developed by "science" all day every day, and is, as such, a hypocrite.Zzubnik (talk) 11:58, 21 January 2011 (UTC)[reply]
Heh, Scientists will say that's exactly why you should trust them, because they are willing to correct mistakes. But really science isn't meant to be taken on trust, the entire point of it is that anyone can duplicate the results for themself. You need to distinguish the different sciences though, some are far more definitive than others. In some fields (physics, chemistry) you can do a direct experiment to answer a question - you should trust those. But in others you only get your info by doing a statistical analysis (some aspects of biology), and those are less reliable. Scientists know this, and do the best they can. Also, there are some fields where the info comes from modeling (climate, cosmology), or basically educated guesses (archeology). Those are the least reliable IMO, because you can't actually do an experiment. That doesn't make them automatically wrong of course, but nothing beats an actual experiment. I hope I don't get in trouble for listing specific fields. But I will note that when physics depends on statistics, it requires a much much higher confidence for experiments than biology does. Ariel. (talk) 12:07, 21 January 2011 (UTC)[reply]
Organisations that refuse to consider that they make mistakes go whacko. Every organisation makes mistakes: quality organisations openly put them right when they become apparant, but bad organisations cover them up to avoid losing face. Correcting mistakes is part of the process of adapting to a changing environment. If they will not adapt, they die. 92.15.25.92 (talk) 12:11, 21 January 2011 (UTC)[reply]
@Sina-chemo: Here's the deal with science and why you can trust it: Humanity arrives at knowledge multiple ways, but we can reduce it down to a few basic methods, broadly speaking:
We can use our senses to observe the world around us, and we can use logic and reason to connect our observations together and draw conclusions about what we observe
We can make it all up
Science does #1. You decide which method is more trustworthy to you. --Jayron32 13:33, 21 January 2011 (UTC)[reply]
I'll note that that was a positivistic (not to mistake with 'positive') view of things. That is, it's not the only one out there. As for the initial question. According to what we were taught in University, all scientific theories do have inconsistencies and blank spots on the field of explainable experimental data. From purely scientific point of view, certain theories are being applied, are used not because they are true, but because they're the ones that are best at the moment at the explaining experimental ovservations and predicting outcomes of planned experiments. I really was amused at the hydrodynamics and heat exchange theories. They have formulae of such beauty, where basically everything is multiplied by each other with degrees like 0.89, 0.43, and then the result is said to be expected to have ~30 % accuracy. Some examples can be seen in Nusselt number. The Nusselt number is one of the things used for calculating heat-transfer processes parameters. And, there are industrial processes which utilize heat exchangers, which exchangers are neither chosen randomly nor have thousands of percent of efficiency reserve. They are built according to calculations. But if existing views were just wrong, heat-exchangers would go hay-wire en masse, in some cases most likely leading to casualties. At the same time I don't think that even a scientism freak would believe that all those numbers are catching the essence of nature and are therefore "true" or absolutely "trustworthy". Still, those numbers are science. And it is because an idea of 'no universal criteria exist' applies to the degrees of trustworthiness as well, original poster's friend has his right to adhere to his own opinion. He's adding to the variety, so I'd approve, but share his views I'd not. If I were to argue with him, I'd push for the point that he doesn't have a thing to trust among his means of physical sustenance then. :) Which may be true, but so what? Physically, nothing has changed after such a declaration. Legate of Skai (talk) 16:11, 21 January 2011 (UTC)[reply]
If you read up about 5 sections, you'll see that I leave a long explanation where I have pre-agreed with everything you have said regarding the nature of "truth" and its irrelevence to scientific thought, even before you said it. The indeterminability of the One Right Answer, and the fact that science is simply unconcerned with such matters is still 100% compatible with the statement I made with regards to the utility of science in acquiring knowledge. --Jayron32 16:18, 21 January 2011 (UTC)[reply]
Is it that hard to fathom what original poster's friend would say to the–in my opinion–crude dichotomy provided as an answer option?.. Such things wouldn't help with "Is that your best?" sort of confusion when confronting sophists. Legate of Skai (talk) 19:21, 21 January 2011 (UTC)[reply]
One does have a form of "faith" in science, as one does not actually re-perform experiments and even practicing scientists cannot possibly know the entire literature at once. But what you are having "faith" in is a system that on the aggregate does review and re-test and challenge its tenets in a systematic way. The goal is to get reliable knowledge about the natural world, plain and simple. The models of science have so far provided a far more reliable model of the natural world than those formed by simply interpreting and re-interpreting the Bible. That does not mean that science is all-knowing or that the conclusions of every study should be trusted blindly. There is a lot of science which is tremendously unsettled at this point, and even entire fields have practices that I think are going to be seen as colossal methodological goofs in future years. Still, science gets us things which definitely "work" — like airplanes, satellites, GPS, computers, and nuclear reactors. If the underlying theories on these technologies were not essentially correct (and they are not intuitive—GPS would not work without General Relativity, modern computers use a good deal of quantum mechanics, and nuclear reactors rely on very specific models for how atoms work), then they would simply fail from the beginning. That's a better track record than any other knowledge system I've ever heard. --Mr.98 (talk) 13:40, 21 January 2011 (UTC)[reply]
One thing to remember is that scientists are still humans, and thus are capable of both errors in understanding, errors in judgement, and outright deception. You can expect to find these character traits in scientists roughly as often as you find them in the rest of the human population. So, while it is true that some scientists (see Andrew Wakefield) lie and cheat and produce deliberately fraudulant statements, that is also true of religious leaders (see Jim Bakker) and politicians (see Richard Nixon) and any other group of people. The question is not whether you can trust every single scientist down to the last person; you can't ask that of any group of people in all of humanity. You need to ask if you can trust science as a process to produce reliable results. If your inclined to such cynicism that you can trust no person about anything, then no one is going to convince you that you should trust science. Insofar as you can place your trust in any human endeavor, even in light of the fact that some humans are not trustworthy, science is a pretty good bet. --Jayron32 13:47, 21 January 2011 (UTC)[reply]
The answer all depends on how you define "trust", and also "science". If you get in an automobile, you "trust science" in that you assume it's not going to explode and kill you; even if you don't go by the engineering but simply see that other people's cars don't usually blow up, that is still a sort of scientific observation, subject to the usual caveats (do your neighbors have Pintos..?). But science doesn't define trust, and it defines science only by providing a theory, which you may or may not know. Ordinary day to day life involves a vast amount of unspoken philosophy, and few if anyone can tell if it is correct. Wnt (talk) 19:42, 21 January 2011 (UTC)[reply]
Scientists are always aiming to get closer to the correct explanation for everything they investigate. Religious folk think they already know. HiLo48 (talk) 23:02, 21 January 2011 (UTC)[reply]
I see people get upset with a normal elevator because they expect it to work like magic. I see people flying in chairs every day (on airplanes, but still). That's how much credibility science has. On the other hand, people aren't surprised when their prayers aren't answered after, say, a year. And prayers for world peace have never been answered. Food for thought. Imagine Reason (talk) 04:49, 23 January 2011 (UTC)[reply]
Whereas Santa Claus gicves you presents every year without even requiring you to pray to Him. 92.24.184.8 (talk) 15:41, 23 January 2011 (UTC)[reply]
I would respectfully suggest that the purpose of prayer may not be to tell an omniscient God what you want, so these experiments do not invalidate it. Wnt (talk) 21:05, 25 January 2011 (UTC)[reply]
the diameter of the nucleus in the atom is 1fm.Does it mean that the protons and neutrons have a certain diameter(or volume Or even shape, spherical, for example)too? what about other subatomic particles? are particle just some small dots with extended properties such as elecric fields? or they have some sort of a size or volume?--Sina-chemo (talk) 11:57, 21 January 2011 (UTC)[reply]
You can define the the radius of an object as the length scale associated with the energy required to probe its structure. So far we know that baryons and mesons do also have internal structure, and thus a finite radius, but other particles, like leptons, quarks, gauge bosons and neutrinos, have, in the energies accessible to modern science, no discernible structure. Thus, to our knowledge, they are point particles. —Preceding unsigned comment added by 129.67.37.227 (talk) 13:36, 21 January 2011 (UTC)[reply]
(edit conflict)At the fundemental level in the atom (electrons and quarks) concepts like "volume" make little sense. If we consider them to be particulate at all, then they are true "point particle"s with no volume. But its not even necessary to consider such entities to be "particles" in the "little ball" sense. In some cases, it makes perfect sense to think of an electron as a standing wave occupying the space of its defined orbital, for example. When an object, like you, has volume, such volume is purely the consequence of, as you put it, the "extended properties" of the many fundemental particles that make it up. Another way to look at it is that volume only exists where fundemental particles interact with other fundemental particles; the volume of an proton is therefore defined by the distances at which the strong nuclear force works in keeping the quarks together. --Jayron32 13:41, 21 January 2011 (UTC)[reply]
The volume of the proton also has an effect in its interaction with the electron in a hydrogen atom, causing (extremely small) shifts in the the allowed energy levels of the electron, and hence of the frequencies of the lines in the atomic spectrum of hydrogen. Having said that, the proton is not a hard sphere, but rather something which is a bit fuzzy with no firmly defined edge – atoms are similar in this respect. The usual measurement of the "size" of a proton is called the "rms charge radius", which is 0.877 fm. So 1 fm for the diameter of an atomic nucleus is a bit small – a few femtometres would be a more accurate description (depending on the nucleus, of course). Physchim62(talk) 14:02, 21 January 2011 (UTC)[reply]
I (in the US) recently bought some Taster's Choice decaffeinated coffee and notice a distinct taste difference from regular, and after reading the decaffeination article, see how it's a challenge to remove the caffeine but leave all the other molecules that provide the original coffee taste. Does anyone know of a US instant decaffeinated coffee that tastes closer to regular than Taster's Choice, because it's almost not even worth it for me to drink this. DRosenbach(Talk | Contribs) 14:18, 21 January 2011 (UTC)[reply]
insofar as its worth it to drink any slightly bitter, brown water which doesn't wake you up?As in, there's a reason to drink preground, canned coffee that isn't related to its caffeine content. --Jayron32 14:23, 21 January 2011 (UTC)[reply]
Some people swear by sanka as the best decaf. In general the swiss water process mentioned in the decaf article is probably best at leaving flavour intact, though it can be hard to tell which method a certain brand uses. In a completely different direction, many people enjoy the naturally caffeine-free postum wish postum still existed. SemanticMantis (talk) 15:03, 21 January 2011 (UTC)[reply]
While postum may not be availible, many people drink chicory root as a coffee substitute, either by itself or mixed 50/50 with coffee. I believe that chicory root has no caffeine in it. --Jayron32 15:58, 21 January 2011 (UTC)[reply]
Yes, if you like chicory, it will make up for some of the flavor lost by decaffeinating. the brand Luzianne sells decaf with chicory. SemanticMantis (talk) 17:03, 21 January 2011 (UTC)[reply]
If "You can define the the radius of an object as the length scale associated with the energy required to probe its structure. So far we know that baryons and mesons do also have internal structure, and thus a finite radius, but other particles, like leptons, quarks, gauge bosons and neutrinos, have, in the energies accessible to modern science, no discernible structure. Thus, to our knowledge, they are point particles." Then can't we apply this argument to black hole radii in that the event horizon is the radius. I mean the black hole as a point particle or singularity argument is simply a result of our inability to properly measure something with no free space inside it like the sub atomic point particles that we know of? —Preceding unsigned comment added by 165.212.189.187 (talk) 14:59, 21 January 2011 (UTC)[reply]
Defining the radius of particles in this way makes sense, as it highlights the 'radius' as the crossover from one regime to another (for example when within the radius of a proton, modelling it as a point electric charge completely fails to describe the effects that are found. This is no different to say modelling a billiard ball as a hard sphere, if you are operating on atomic scales, or with energies capable of smashing the ball, you will find that your experiments do not detect something that behaves like a hard sphere). The reason that a Black Hole has radius is slightly different, the event horizon instead describes a radius within which no information can escape. The black holes existence and dynamics have their origins in the distortion of the universe's geometry, rather than in the properties of the objects that make it up. —Preceding unsigned comment added by 129.67.37.227 (talk) 15:20, 21 January 2011 (UTC)[reply]
So that would suggest that a black hole is not a singularity as in the size of a point particle but rather a singularity because the "measurable" distance from one point on the event horizon to the opposite point is zero, as a result of our inability to accurately measure that distance, right? —Preceding unsigned comment added by 165.212.189.187 (talk) 15:42, 21 January 2011 (UTC)[reply]
No, it's more complex than that. The measurable distance inside the event horizon from one side to the other is zero. The measurable distance across the event horizon as measured by a stationary observer outside of is a finite, measurable distance. But the equivalent measurement taken inside of the event horizon would be exactly zero; that is the singularity being refered to. Its not as simple that there is some point at the center of the event horizon which around which the event horizon is projected like a sort of cloud. It can be modeled that way to an external observer (that is, we tend to think of a black hole in those terms), but the gravitational distortions in terms of the effect of the black hole on spacetime is such that the internal structure is literally a singularity. The reason this is different from, say, quarks or electrons as "point particles" is that, from an external observer, electrons really are a point with no dimensions. For an external observer of a black hole, the "event horzion" has apparent dimensions and an apparent volume. --Jayron32 15:53, 21 January 2011 (UTC)[reply]
No, that is wrong. There is spacetime between the event horizon and the singularity, and this spacetime looks (locally) just like any other spacetime -- there are lots of different points/events inside, separated by positive time and space intervals. It is not true that an observer inside the horizon cannot measure any distance, for example. All the horizon means is that he cannot tell anybody outside of it about his measurement, and that he has limited time to enjoy his knowledge before he splats into the singularity. –Henning Makholm (talk) 20:01, 21 January 2011 (UTC)[reply]
Henning, OP here. I mean within the singularity because the density "pushes it all out" so the free space that "should be" where the singularity is, is instead condensed all around it, which I believe creates the horizon. Can you address how both the point particles and black hole singualrities interact with free space? Thanks. —Preceding unsigned comment added by 165.212.189.187 (talk) 14:23, 24 January 2011 (UTC)
So then the black hole's radius is the event horizon or very close to it, and not infinitely small, right? —Preceding unsigned comment added by 165.212.189.187 (talk) 18:22, 21 January 2011 (UTC)
But black holes and point particles are similar in that they both cannot be measured due to the fact that there is no free space inside them. —Preceding unsigned comment added by 165.212.189.187 (talk) 18:37, 21 January 2011 (UTC)[reply]
Scientists who study black holes would rarely use the term "radius" because that word is ambiguous. They would use the term event horizon. When defining the geometry, they would use an Einstein tensor in 4-space. By definition, a "radius" is a one-dimensional measurement. Thorough, rigorous, and correct analysis of a black hole requires general relativity, and it is atypical (if not impossible) to construct general relativistic gravity field equations in one dimension. (The geometry described by relativity just isn't one-dimensional). So, if you want to communicate about black holes in an unambiguous way, you will not describe a "radius." You will present a 4x4 tensor, and demonstrate that this results in a singularity along a surface, called an event horizon. It so happens that if you project this surface in to a Cartesian space and "ignore" the singularity for a moment, you'll look like you are describing a sphere with a radius; but that's going to give rise to logical conundrums as described above (for example, the size of the measured radius is different, depending on whether you are inside or outside the sphere). Nimur (talk) 19:25, 21 January 2011 (UTC)[reply]
The event horizon is not a singularity. It is a hypersurface that surrounds a particular region of spacetime; the surrounded region contains a singularity, which is different and distinct from the horizon. –Henning Makholm (talk) 20:01, 21 January 2011 (UTC)[reply]
No, but behavior around the event horizon is very, um, strange. For an observer falling towards a black hole, neither the observer themselves, nor anyone watching the observer from afar, will see the observer "cross" the event horizon. The observer sees no change at all in their environment, and falls, from their point of view, for an infinite amount of time, or until tidal forces spagettifi them. An external observer will watch the faller decelerate and become arbitrarily close to the event horizon, without ever crossing it. One can calculate the exact moment where one should cross the the event horizon, but no observation ever shows this occuring, because of the effects of gravitational time dilation. The event horizon is not the singularity itself, but every point inside of the event horizon is the singularity... --Jayron32 20:21, 21 January 2011 (UTC)[reply]
No, that is just wrong, almost all of it. An observer falling into the hole can calculate when he crosses the horizon if he knows the geometry of the hole (he will have to calculate it because nothing particularly momentous will happen to him at that time). After crossing the horizon, he experiences a finite amount of time before he necessarily reaches the singularity, (ignoring the fact that he will be spaghettified first). The horizon crossing happens at a definite time and place in spacetime. Just because light from the horizon-crossing event never reaches the outside observer, that doesn't mean that this observer is going to conclude that the horizon was never crossed. To the contrary, knowing the spacetime metric he has no trouble compute when each of the bits of light he does eventually receive must have left the infalling object. He can easily plot these results and find that they converge towards a particular point in spacetime, and can infer that at that point, the object crossed the horizon. In particular he will not conclude that the faller ever decelerates, unless he is stupid or careless enough to fail to correct his data for the increasing lightspeed delay between something happening and him seeing it. Finally, as I have said before, there are plenty of points in spacetime that are inside the horizon yet different from the singularity. –Henning Makholm (talk) 22:11, 21 January 2011 (UTC)[reply]
Thank you Henning for adding detail to the discussion. As I stated below, I was sketchy on some details. If your description of black holes is more correct than mine, then could you perhaps also correct the article Black hole, which contains the following statements. "Due to this effect, known as gravitational time dilation, an object falling into a black hole appears to slow down as it approaches the event horizon, taking an infinite time to reach it." That is plainly wrong, and I would appreciate it if you could fix it. As far as what happens inside of the black hole, I readily admitted below that my mathematical background was not strong enough to derive the geometry. Thank you for clearing it up for me as far as that goes. --Jayron32 23:09, 21 January 2011 (UTC)[reply]
There isn't necessarily an inconsistency between what the article says, and what Henning is saying. It all really boils down to the difference between "appears to" and "concludes that".
The article is correct, assuming I understand black holes correctly. As an object gets very close to an event horizon, it does "appear to" a distant observer to slow down, in that: A) If the object is between the observer and the black hole, the angle subtended by the object as seen by the observer will decrease more slowly than does the angle of an object traveling away at constant speed in empty space, and indeed, the angle subtended approaches a finite limit instead of zero. And B) If the object is approaching the black hole from what appears to the observer to be the side of the black hole, the pixels per frame that the object's image in the observer's video camera moves decreases with time, and the object's image approaches a fixed position in the frame, corresponding to where the event horizon is, without ever actually quite reaching that position.
I guess Henning's point is that it would be "stupid" or "careless" to conclude from those observations that the object was really decelerating, because those observations alone don't take the finite speed of light into account at all. From a general relativity perspective, the object is neither decelerating or accelerating (assuming it isn't using thrusters or something). Like all objects in free fall, the proper acceleration of the object is zero. And any other kind of acceleration is just a coordinate "acceleration", that depends entirely on one's choice of coordinates, and isn't a real, physical acceleration at all.
The above might give the impression that the outside observer will be able to see the infalling object forever, hanging just outside the event horizon. That's not really true. The object's image will very rapidly get red shifted to the point where the wavelengths of light that came from the object are too huge for the light to be detected by any method. Red Act (talk) 02:31, 22 January 2011 (UTC)[reply]
Thanks for the support. There are a lot of misunderstandings and falsehoods about black holes and event horizons floating around, mostly because the truth is really really hard to explain without inviting misunderstandings, except by using more complex mathematics than most audiences are willing to learn.
I can think of at least two or three different senses in which an infalling object can more-or-less reasonably be said to take infinite time to reach the horizon, each of which desperately needing the caveat "but this does not mean what you think it does". There's even a respectable way to call the horizon a singularity -- namely, in the standard Schwarzschild chart the horizon is a "coordinate singularity", but again that does not mean what one would think it does. (It just refers to a feature of the mathematical model being employed, which, so the mathematics itself says, has no actual physical content). –Henning Makholm (talk) 07:57, 23 January 2011 (UTC)[reply]
As an addendum, I think the scale length of a black hole, as measured from inside the black hole, is ∞ (not zero). If you are inside the event horizon, and want to move to any other point, it will take an infinite time to traverse (and hence to exit), no matter what speed you travel at. But I would also point out that in certain geometries, zero and infinity are congruent. The simplest case of this is the projective space (which, while a nice mind-bender of a geometric space, is not a solution to general relativity). Again, we can't really expect logical continuity when we are using the wrong geometry to describe a black-hole. Nimur (talk) 19:31, 21 January 2011 (UTC)[reply]
Correct me if I am wrong, because my math in this area is nonexistant, but my understanding about the internal geometry of a black hole as being "zero volume" comes from the fact that, from the point of view inside, all points are "compressed" into the singularity, and thus occupy the same location in 4D spacetime, and are thus identical in location. Two points that occupy the same exact location have zero distance between them, n'est ce pas? --Jayron32 19:39, 21 January 2011 (UTC)[reply]
I'll second that, pointing out that as I understand it, the singularity is in the future of those falling into the hole. Not in the sense that they'll reach it in the future, but that it is the future, because their light cones point at it. Wnt (talk) 19:45, 21 January 2011 (UTC)[reply]
Thanks that was helpful, but with all this focus on black holes, the actual question about their similarity to point particles was ignored. Could someone please address this observation? Additionally, could black holes be a giant atom like "blackholeum" with a giant nucleus and an electron cloud(event horizon)? —Preceding unsigned comment added by 165.212.189.187 (talk) 20:14, 21 January 2011 (UTC)[reply]
There is no similarity to point particles. Black holes have an inside, which has no internal volume. Point particles have neither an inside, nor a volume. --Jayron32 20:23, 21 January 2011 (UTC)[reply]
Could you please expand on the difference between no internal volume and no volume (point particle)? —Preceding unsigned comment added by 165.212.189.187 (talk) 20:31, 21 January 2011 (UTC)[reply]
Sure, I explained this above at least once, but we'll try again. To an observer from outside a black hole, the event horizon occupies (surrounds) an apparent volume of space. You can fly around one, take measurements, and calculate an apparent volume that the event horizon would encase, if, for example, it were an ordinary star. However, because of the warping of spacetime by the singularity inside of the event horizon, the black hole itself compresses all of the space that would appear to be inside of the event horizon into the exact same location. By definition, any two points that occupy the same location have no distance between them; so there is no volume. By contrast, a point particle has no apparent volume to any observer. If you look at a point particle, it does not appear to occupy any amount of spacetime, unlike a black hole, where you can measure the dimmensions of it from a vantage point outside of the event horizon. You cannot measure any dimensions of a point particle from any vantage point. --Jayron32 20:57, 21 January 2011 (UTC)\[reply]
Most of these claims about black holes are wrong. See above. –Henning Makholm (talk) 22:11, 21 January 2011 (UTC)[reply]
See above. Could you fix the Black hole article then so that we can stop telling people wrong things? Thanks! --Jayron32 23:09, 21 January 2011 (UTC)[reply]
What you said about the apparent volume enclosed by the event horizon is correct, and that is how the quantity called "black hole radius" is defined. But "the black hole itself compresses all of the space that would appear to be inside of the event horizon into the exact same location" is wrong, or at least I don't understand what you mean by it. There is no sudden change in the structure of spacetime at the event horizon. -- BenRG (talk) 01:33, 22 January 2011 (UTC)[reply]
Black holes have variable mass, whereas all particles of a given type have the same rest mass. (Then again, is the mass of a black hole a rest mass?) I suppose every different mass of black hole would be a different "particle", in a sense, which interacts with other particles by eating them and becoming a higher-order black hole?
We should ask whether the mass, charge, and spin of black holes are quantized. I don't think there is any doubt that the charge will vary in the usual increments. The spin should also, one would think - a black hole should eat or emit photons with angular momentum hbar. Now whether a black hole is a boson or a fermion (can it be absolutely without spin or only plus or minus hbar/2) - I'll let someone else work on that a while. But the mass, well, a black hole can eat all sorts of particles, and we're aware of no underlying common denominator of their masses, so what kind of quantization scheme describes a black hole's mass? Wnt (talk) 20:55, 21 January 2011 (UTC)[reply]
Jay, could you rephrase this "You cannot measure any dimensions of a point particle from any vantage point." to include "yet" or "with our current tech." at the end, since that sound like the famous last words of some physicist in the 1800s?. —Preceding unsigned comment added by 165.212.189.187 (talk) 21:15, 21 January 2011 (UTC)[reply]
It's not a technological limitation; it's a definition. If there were any way to measure a dimension, then the particle would not be a point particle at all. That's what being a point particle means. –Henning Makholm (talk) 22:11, 21 January 2011 (UTC)[reply]
The quantity called "the radius of a black hole" is the reduced circumference of the event horizon. The "reduced circumference" is simply the circumference divided by 2π, i.e., the radius that a circle with that circumference would have in ordinary flat space. Obviously, practical experiments on black holes are difficult—for one thing, we don't have any to experiment on—but in principle you could build some kind of wire-frame structure just outside the event horizon that encloses it on all sides, then disassemble it and reassemble it somewhere else, and the result will be a sphere whose (now directly measurable) radius equals the radius of the black hole. That radius doesn't have any literal meaning when applied to the black hole itself, but that doesn't mean there's no space inside the black hole. The inside is very similar to the outside, according to the theory at least.
There is probably a close relationship between black holes and elementary particles in quantum gravity (this is just personal prejudice, really, but it's a fairly common prejudice among particles physicists, I think). For starters, you can't really have point particles in general relativity because they're too dense—they ought to collapse into black holes. If elementary particles were black holes, you would expect them to radiate away their excess mass and evaporate—and that's what they do, conservation laws permitting, except that it's called particle decay. So it's quite appealing to think of the world as consisting entirely of black holes in vacuum, with the funny low-energy fermion spectrum (electrons and whatnot) resulting from some kind of small-scale tweaking of the rules of general relativity. If you're wondering why this hasn't been developed into a working theory of quantum gravity, it's because it doesn't actually work very well. One big problem is that black hole electric charges have to satisfy |q| < m, in natural units, and electrons violate that bound by a factor of about 1021 (this is one aspect of the hierarchy problem). One way of solving that is to introduce large extra dimensions, and that's a big part of the reason many particle physicists were/are hoping for evidence of large extra dimensions at the LHC. I think the LHC has already ruled out some versions of this idea, but I don't know the details. -- BenRG (talk) 01:33, 22 January 2011 (UTC)[reply]
Oklo reactor and the fine-structure constant[edit]
The articles say that the isotope ratios are consistent with alpha actually staying constant, but The Disappearing Spoon by Sam Kean points out that the isotopes of samarium are in the wrong proportion. --J4\/4 <talk> 17:19, 21 January 2011 (UTC)[reply]
As I understand it, aging is caused by cell replication being imperfect. Cells are copied from copies of copies and over time this results in degradation, like photocopying a photocopy over and over. So the solution would seem to be; introduce cells which have not suffered degradation into the body for the replication process to use. Is this biologically possible? What would be the limits of doing this? Could a person theoretically live forever using this method? 149bbac79bf1bc39671cee9d04cfb7d2—Preceding unsigned comment added by 188.163.48.105 (talk) 19:40, 21 January 2011 (UTC)[reply]
The brain. You could theoretically replace any part of your body after it degenerates other than the brain - once that is gone, there's no getting it back, at least not in the shape yours was. From the brain cells article: "Neurons of the adult brain do not generally undergo cell division, and usually cannot be replaced after being lost, although there are a few known exceptions." TomorrowTime (talk) 19:49, 21 January 2011 (UTC)[reply]
I second the statements by TomorrowTime. Note also that most neuroscientists believe that memories are stored in the connections between brain cells, so if you somehow managed to replace all the brain cells with new ones, you would presumably lose all your memories in the process. Looie496 (talk) 02:03, 22 January 2011 (UTC)[reply]
I think that the brain has more regenerative capacity than it's given credit for. I was just reading that Jim Brady actually has made a substantial recovery over the past 30 years. And a shortage of neuroblasts seems to be associated with depression. While it may be that complete replacement of all the brain's cells and regrowth from scratch would be a reset, it also appears that memories are constantly being recalled and rewritten, so if cells gradually turn over, it doesn't necessarily mean a loss of all the information. Wnt (talk) 06:07, 22 January 2011 (UTC)[reply]
Yesterday I saw Dr. Vince Teofilo speak at Lockheed's Advanced Technology Center[7] about inertial electrostatic confinement (IEC) for boron-11 + proton fusion, which avoids the problem of neutron activation creating nuclear waste from D-T fusion, but there are questions as to whether it can break even. However, Dr. Teofilo was very optimistic about non-maxwellian plasma, beam-beam type fusion which has recently been achieved in IEC devices. I asked about bombarding solid 11B with a proton beam. Dr. Teofilo said to look at Wikipedia's Proton target fusion article, but there isn't one and I can't find anything about it. Does the energy at which protons must be accelerated in order to fuse with a solid boron target exceed the resulting output energy? The boron article says 0.5 MeV in for 8.7 MeV out, but does that assume the boron is already ionized, and what if it isn't; can the necessary energy be front-loaded into the proton's momentum? 71.198.176.22 (talk) 20:01, 21 January 2011 (UTC)[reply]
The phrase "proton target fusion" barely appears on the web at all, but we do have an article on aneutronic fusion, which looks like the topic of his talk from the blurb. I can't answer your more specific questions as I am not smart. --Sean 20:17, 21 January 2011 (UTC)[reply]
Most people don't know what aneutronic fusion is, so you are smart. Keep trying to achieve your desired level. 71.198.176.22 (talk) 00:06, 22 January 2011 (UTC)[reply]
Related question: What would happen if a proton with 0.5 MeV plus the Boron-11 atom's ionization energy collided with a Boron-11 atom held in place by a crystal structure? 71.198.176.22 (talk) 00:19, 22 January 2011 (UTC)[reply]
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