Wikipedia:Reference desk/Archives/Science/2011 November 7

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.

November 7

Explaining those who claim to communicate with God

How best to explain those who claim to communicate with a god? Delusional? Charlatans? Brain not working properly? I'm not referring to people who simply pray, but to those who might say "God told me to..." or "I received a message from the Lord..." etc. These people are far fewer in number, but still quite common... The Masked Booby (talk) 01:15, 7 November 2011 (UTC)

You mean, how differenciate between true and false communication events? Plasmic Physics (talk) 01:24, 7 November 2011 (UTC)

Well, they can't all be true. So why don't you stick to those claiming to communicate with what you believe is a false god? HiLo48 (talk) 01:28, 7 November 2011 (UTC)

Don't you mean "those falsely claiming to communicate with what you believe is god?" Plasmic Physics (talk) 01:34, 7 November 2011 (UTC)

No, but that would be an interesting category too. HiLo48 (talk) 01:39, 7 November 2011 (UTC)

I suggested it, because he never agrued for or against the falsity of God. Plasmic Physics (talk) 01:43, 7 November 2011 (UTC)

I concur — Preceding unsigned comment added by 203.112.82.1 (talk) 01:54, 7 November 2011 (UTC)

The question leaves many holes before it can be answered, because it can be interpretted in many ways:

First, one has to establish if the question presuposes the existance of God or not. If the question assumes God exists, it changes the nature of the meaning of the question than if the question assumes God does not exist. Secondly, one has to establish the mindset of the voice-hearing person in light of the first point. So you have all of the following permutations:

• If God does not exist, then the voice-hearer can either be delusional or outright lying.
• If God does exist, then those options exist, but a third option, that they actually hear God, also exists.

If the God aspect bothers you, you can subtitute something else in there. For example, a person may claim to have talked to their friend Bill on the phone. Now, the same scenarios could exist: Bill may not exist at all; and the person who claimed that fact could be lying or could be delusional. Bill may exist, which means that the person who claimed to talk to him on the phone may have actually done so, but that doesn't eliminate the possibilities that they are either lying or delusional. --Jayron32 02:00, 7 November 2011 (UTC)

203.112.82.1: It's nice to know that you are very agreable, but if you are intermittently adding "I concur" to section in the reference desk just so sound intellectual without adding any scientific value to the arguement then it starts to look strange. Just because someone has crazy hair and a German accent doesn't mean that he's a genious like Einstein was. Plasmic Physics (talk) 02:06, 7 November 2011 (UTC)

"To be a genius is to be misunderstood", but the converse is not necessarily true. --Jayron32 02:09, 7 November 2011 (UTC)

See here. Count Iblis (talk) 02:18, 7 November 2011 (UTC)

This [YouTube 0:40] PSA states that "If you talk to God, you are religious, but if God talks to you, you are sick. Schizophrenia is treatable." Our Schizophrenia article does discuss auditory hallucinations, but does not discuss religiosity in any depth. Note that some who claim to hear God may, when further question, not describe auditory hallucination but instead describe an "inner voice" which they attribute to God, suggesting mere delusion. Religious hallucination and Religious delusion are both redlinks and Voice of God discusses something else entirely. Don't we have an article on this? -- 49.228.87.218 (talk) 02:47, 7 November 2011 (UTC)

That's is an insulting statement, to say that all instances are false. I've witnessed someone experience a "He told me to..." event, and they are most definitely not schizophrenic or deluded. Plasmic Physics (talk) 04:05, 7 November 2011 (UTC)

It's not an actual PSA, just one guy's homemade video. And of course many religious believers who are quite sane by all objective measurements have had occasional moments when they felt that God was communicating with them in some manner - sometimes not such much in hearable words but by a definite sensation or impression made upon the mind. For most such folks, it's a rare and often unexpected thing, and accomplishes some good purpose. Even non-believers sometimes experience something unusual or uncanny that seems to be unexplainable in ordinary terms. Just about everyone I've ever known has had some sort of "supernatural" experiences along the line, at wide intervals. Yet from there to fanatical believers who talk as if God is chatting with them like a talk-show host every day of the week, is a big leap. And then down to certifiable types who are truly delusional and have to be hospitalized is another leap. It's important to distinguish among the three kinds. Textorus (talk) 04:56, 7 November 2011 (UTC)

Oops. I apologize for misrepresenting that video if it is not an actual PSA. I thought that it had the look of the real thing (aside from the "Acid Atheist" splash at the start and the English subtitles, which I assumed had been added on). -- 49.228.87.218 (talk) 06:59, 7 November 2011 (UTC)

It appears I have misjudged many of the participants of this desk. I assumed that by posting this question to the Science desk the assumption that there are no gods would be implicit and obvious. That's why this isn't on the Humanities desk... With one eyebrow firmly raised, The Masked Booby (talk) 05:00, 7 November 2011 (UTC)

There is no religious test one way or the other required to participate on these desks. If you want to hear answers only from firm atheists, it would be more helpful to specify that in your question so that no one else wastes your time. But then, if you have already predetermined that there cannot possibly be any communication whatsoever from a god or gods, then obviously any such claim must either be self-delusion or the result of a fraud by a third party, and you've answered your own question before you asked - so what else could anyone tell you? Textorus (talk) 05:19, 7 November 2011 (UTC)

They could tell me whether it is more likely conscious (fraud) or involuntary/subconscious (mental disorder), which, you will note if you read carefully, I make clear in the original question. There is plenty to answer, thank you. The Masked Booby (talk) 05:32, 7 November 2011 (UTC)

Well, then, let me suggest that my reply above is relevant to your question. You seem to be assuming that "all members of group X" - i.e., people who claim that God has spoken to them - are, in the absence of fraud, crazy. But this is a logical fallacy; as I pointed out, there are at least three different kinds of people who might make such a claim, in one sense or another, so to get the intelligent answer you seek requires more nuance in your question. There are many varieties of religious experience - and on that note, I wonder if you have ever read psychologist William James's famous work, The Varieties of Religious Experience? I have a feeling that you would find it very interesting. Textorus (talk) 07:12, 7 November 2011 (UTC)

Science has not disproved the existence of God, so the appropriate attitude should not be to take sides. As for how people get messages from God, it's generally a matter of interpretation. To use some classic examples, many people might have a dream of seven lean heads of grain and seven fat heads of grain and assume that it was simply a dream, or if not, then call it prediction or even precognition but not assume that it was a divine communication. Many people seeing a wheel within a wheel in the sky would call it a flying saucer, blame pranksters or aliens. We are all surrounded by unfathomable amounts of information we don't understand - birdsongs, the patterns of raindrops falling from the sky, the minute-to-minute fluctuations of the stock market, the numeric sequence of the digits of pi. People try to read information or meaning or intelligence into these things because it's there - somewhere - but doing so is a difficult task. Is a divine communication part of that meaning? Hard to say... even harder still to define what a "yes" or a "no" would mean. Wnt (talk) 05:24, 7 November 2011 (UTC)

There is nothing to disprove. Science does not disprove. Burden of proof etc etc but you're well off the topic. The Masked Booby (talk) 05:32, 7 November 2011 (UTC)

Alright, to be more precise, science has not proposed any experiment capable of determining the existence or nonexistence of an omnipotent entity, as such an entity is capable of altering, avoiding etc. any detection mechanism. Wnt (talk) 15:59, 7 November 2011 (UTC)

Mmm, I'm not sure that's quite true, that "science does not disprove." Have scientists not very effectively disproved the existence of Luminiferous aether, phlogiston, spontaneous generation, and the Ptolemaic system, among many other things? Textorus (talk) 07:31, 7 November 2011 (UTC)

Keep in mind that it's possible (science hasn't poven this incorrect) that an all-powerful entity could exist outside the (many?) universe(s)as we know it/them. That would make it much harder to science to disprove theidea of any type of god, as well as harder for religious people to prove the existence of such an entity. Both religious people and scientists could very well be correct. Heck froze over (talk) 04:05, 10 November 2011 (UTC)

Personally I think that if there really is a god(s), he could have done a much better job. If the god(s) are perfect, we wouldn't need to pray, we'd always make the right choice, and as a result the devil would have no traction. There would be no wars, haters, racists, etc. Heck froze over (talk) 04:09, 10 November 2011 (UTC)

Some people use the phrase "God told me to ..." very broadly or metaphorically. It often doesn't literally mean that they heard the voice of God commanding them to do something. Sometimes it means that they thought of a new, but risky, path they wanted to take in life, prayed for wisdom and guidance for a while, and afterwards still thought it was a good idea. APL (talk) 05:44, 7 November 2011 (UTC)

Wnt: the person whom I witnessed, acted as intercessor. The person received a vision, and described it to the assembly, giving them a chance to identify themselves as the intended recipent. This was followed by a clear and unambiguous message. I was infact the intended recipent. Plasmic Physics (talk) 05:50, 7 November 2011 (UTC)

Our articles Revelation and Direct revelation do not discuss psychology, but Religious experience does include the section Scientific studies on religious experience. You may also be interested in our Speaking in tongues#Scientific explanations and its subsections "Neuroscience", "Mental illness", "Hypnosis", "Learned behavior". -- 49.228.87.218 (talk) 08:40, 7 November 2011 (UTC)

From a purely materialist point of view, there seem to be quite a lot of plausible explanations because the number of phenomena you are discussing are quite varied. There isn't just one "talking to God" phenomena. In some cases you have people who are hearing audible or visual hallucinations (which can have a lot of causes), in some cases people are just being imagining that God would like whatever they happen to like (I suspect many of the politician's "God told me to run for office" falls into this category), in some cases you're getting some kind of psychological wishful thinking along the lines of a Ouiji board (I can make false conversations in my head with someone unpredictable results, but I have no doubt they're just some sort of runoff from background processes), and in some cases you're probably getting outright charlatans. Distinguishing between mental illness and the other categories is probably not too hard (the God of the mentally ill often does not lead one to do things that are beneficial to one's self, while all of the other Gods more or less do), but distinguishing between the other categories is probably not possible externally at this point (perhaps brain imagining technology will be able to do this someday, though).

Personally I do not think that from a scientific point of view there is much reason to entertain the possibility of a real communication. The simpler explanation is that humans have complicated psychologies and complicated neuroscientific makeups. We see this every day, we see this clinically, we can test it, categorize it, analyze it. Having a multitude of contradictory communications from actual or false deities with only a few, specific, often quite mundane instances being valid, seems like the rather extraordinary position. Were I a religious man (I am not, plainly) I would not dispute this fact — I would agree, heartily, that being actually spoken to by God was a tremendous assumption, and a remarkable show of faith, and so forth. --Mr.98 (talk) 16:00, 7 November 2011 (UTC)

People who claim that god talks to them are probably mentally ill, but because of political correctness, and the fact that there are a lot of people who are theists, their illness is often ignored or worse, believed. Science doesn't deal with god because it can't be falsified. See not even wrong. Science does not deal with disproving claims that have no evidence supporting them. It's sad that otherwise intelligent people believe in something that is clearly irrational and baseless, only supporting their belief on "faith" which just means believing in it without evidence. The fact of the matter is, even intelligent people are negatively influenced by precognitive biases based on how they were raised, the culture they grew up in, etc. They are, after all, only human and suffer from the same psychological defects that all humans suffer from. Users like Plasmic Physics, who is otherwise intelligent and knows about science, doesn't employ his own skepticism and knowledge of how science works, to his own religious beliefs because he is biased towards it. ScienceApe (talk) 20:27, 7 November 2011 (UTC)

To elaborate on this a bit more, if I claimed I was communicating with the ghost of Napoleon, that claim would carry the same merit as claiming I was communicating with god. They both have exactly the same amount of evidence supporting them, which is none. The only difference is, the vast majority of people do not believe Napoleon exists as a ghost, while many people believe in god, so while no one would take issue with believing someone who believes they are genuinely communicates with the ghost of Napoleon is mentally ill, they would not believe the person who communicates with god to be mentally ill because of their own biased, irrational beliefs agree with the individual who claims they are communicating with god. ScienceApe (talk) 20:35, 7 November 2011 (UTC)

I forget if this has been mentioned before, but hallucination is not rare and not just suffered by a small minority of delusional people. We all hallucinate at night (dreaming), which explains cases where people claimed to have communicated with god at night. During the day, occasional auditory hallucinations are commonplace. Even those who suffer frequent auditory hallucinations don't have a widely recognized mental disease--see Hearing Voices Movement. --140.180.16.167 (talk) 20:54, 7 November 2011 (UTC)

It sounds more like you are trying to make their hallucinations more acceptable. Basically an apologetic for theists. You're going as far as trying to suggest that hearing things that aren't there is not mental illness. It is. This is the problem with theism being so widespread. You begin to rationalize their behavior so that it's more acceptable as opposed to if it were applied to anything else (like hearing Napoleon talk to you), it would not be. Hallucinating and dreaming are also not the same, hallucinating is done in the conscious, awake state. ScienceApe (talk) 23:39, 7 November 2011 (UTC)

Where did I rationalize the behavior, or suggest that hearing voices from God is different from hearing voices from Napoleon? I'm an atheist, and just like all scientists (theist or not), I'm not saying that hallucinations have a factual basis. However, it is in fact true that most people experience at least one auditory hallucination some time in their lives. It's also true that many people who hear voices aren't diagnosed with a mental disease. Those are facts, not opinions. The opinion I expressed was that the high frequency of hallucinations might explain the frequency of claimed religious communication--after all, if everyone's hallucinating, at least some will be hallucinating about god. --140.180.16.167 (talk) 02:57, 8 November 2011 (UTC)

It doesn't matter if you're an atheist or not, you live in a society where theism is acceptable, so you would still apologize for them. If those are facts, then you need evidence to back then up, because I'm not buying your claims without them. ScienceApe (talk) 04:32, 8 November 2011 (UTC)

Well, in reference to my case, it sound statistically unlikely that the person whom I witnessed had hallucinations or other symptoms of a neurological disorder, based on the specificity of the information content delivered in the vision and message. Plasmic Physics (talk) 01:44, 8 November 2011 (UTC)

But that assumes that hallucinations have low specificity in terms of the information content delivered. What evidence do you have of that? Dreams are often very specific to the person's life, and they happen when brain activity is very low, unlike hallucinations during the day. --140.180.16.167 (talk) 03:01, 8 November 2011 (UTC)

No, you're miunderstanding. The quality of the information used to identify the intended recipent was very specific, the constraints excluded 99% of the sample population. Plasmic Physics (talk) 04:10, 8 November 2011 (UTC)

I don't even know why you believe in god in the first place plasmic. There's no evidence that it exists, and your friend telling you that he talks to god is not evidence either. ScienceApe (talk) 04:32, 8 November 2011 (UTC)

Are you sure you weren't the victim of a fraudster? As the case of psychics (who I presume given your religious beliefs you accept are usually fraudsters) show, it's fairly easy for people to pretend to know details of someone's life by a variety of cold reading techniques, even more so if the target wishes to believe. Even if the person wasn't being intentionally deceptive, have you considered the possibility that because they genuinely believed they'd received a message from god, they unintentionally and without realising did a similar things to what fraudsters do when they decided you were the one who the 'message' was intended for. Nil Einne (talk) 14:36, 8 November 2011 (UTC)

Yes, I'm sure the person was not a fraudster, they had no prior knowledge about me. Infact they did not know who the message was for untill afterwards. Plasmic Physics (talk) 06:10, 9 November 2011 (UTC)

I don't think that is related to the question, and please don't disrespect me by calling Him an it. I respect your decision to be an atheist. Plasmic Physics (talk) 05:15, 8 November 2011 (UTC)

Actually it is related to the question, because you are presuming that it exists, and it doesn't. Therefore the answer you gave actually presumed you can have genuine conversation with this fictional entity. And it is an it because unless it produces spermatozoa, and has the biological function of fertilizing the opposite sex of its species, it's not a male. I don't respect your decision to be a theist, because you should know better, and your warped belief in a god perverts the genuine quest for knowledge in science. I also couldn't care less about respecting christianity when they teach their followers that people who don't accept jesus christ as their lord and savior DESERVE to be tortured for an eternity in hell. Any religion that teaches that doesn't deserve any respect. You're letting your preconceived biases interfere with rationale thinking. ScienceApe (talk) 14:05, 8 November 2011 (UTC)

Highlighting your own god brings me back to a point I made near the start. Surely a devout Christian must wonder about non-Christians who believe in other gods. You can't all be right. If those others say they hear from their god, the OP's question applies there. How can that be explained? HiLo48 (talk) 07:29, 8 November 2011 (UTC)

Easily, being a devout Christian myself, we see communications by other gods as strategic subversions by Satan who masquerades as those gods. Plasmic Physics (talk) 10:40, 8 November 2011 (UTC)

Whereas, since Christianity is not a small, monolithic sect but a very big tent covering many divergent points of view, it must also be said that other Christians, equally devout, do not "succumb too easily to the temptation to exclusiveness and dogmatic claims to a monopoly of the truth of our particular faith," but "in humility and joyfulness acknowledge that the supernatural and divine reality we all worship in some form or other transcends all our particular categories of thought and imagining." --Archbishop Desmond Tutu, God Is Not a Christian: And Other Provocations, 2011. Textorus (talk) 12:05, 8 November 2011 (UTC)

Or maybe your god doesn't exist, and christians made that up to coerce people into being christian and demonizing other religious beliefs at the same time? That would be the real answer. ScienceApe (talk) 14:10, 8 November 2011 (UTC)

It's also illogical to demonize all Christians as ignorant, intolerant oafs. Some are, to be sure, but many millions are not so smug and self-righteous as you assume. The same applies to many other religious people around the world. As well as to atheists. Textorus (talk) 15:32, 8 November 2011 (UTC)

I didn't say they were all ignorant, intolerant oafs, you're arguing a strawman. I said believing in god is illogical. I said their religion teaches that people who don't accept jesus as their lord and savior deserve to be tortured for an eternity in hell. I don't respect religions that teach that. Saying atheists can be smug or self-righteous, is about as meaningful as saying that people who don't believe in Santa Claus can be smug or self-righteous. Atheism isn't an ideology, it's a single stance on a single issue. ScienceApe (talk) 18:48, 8 November 2011 (UTC)

Where in scripture does it say that anyone will be tortured for eternity in hell? That belief is unchristian. Plasmic Physics (talk) 20:41, 8 November 2011 (UTC)

After debating with christians and theists for so long, I've found that citing verses from the bible is a useless exercise. The bible could say snow is white, and then a christian would interpret it as saying it's black. That's the other problem with chrisitianity. You have a bible that apparently doesn't mean what it says, it means whatever you want it to mean. But in debating all of these christians, the one thing they always say is that unless I accept jesus as my lord and savior, I am destined to be tortured for an eternity in hell. Apparently this all powerful and all knowing god is quite conceited and immature. ScienceApe (talk) 04:41, 9 November 2011 (UTC)

Well, they have it wrong then. Torture is mentioned nowhere, neither is hell a place where someone is sent, hell is an event. Plasmic Physics (talk) 06:10, 9 November 2011 (UTC)

What does it say in simple english? Plasmic Physics (talk) 12:18, 8 November 2011 (UTC)

Why don't you read the entire excerpt and decide for yourself? I just wanted to make the point that your reply to HiLo does not represent the views of all devout Christians everywhere. Textorus (talk) 12:49, 8 November 2011 (UTC)

That depends by what you mean by devout. Now that I've read that excerpt, I can tell you that it is heretical, as in it speaks against scripture. Plasmic Physics (talk) 20:41, 8 November 2011 (UTC)

For me, "devout" means to actively persue humility, rightouness, and truth. A truly devout person would make certain that what they are told is in complete agreement with scripture, otherwise there is room for error. Inspired by Acts 17:10-12. Plasmic Physics (talk) 23:50, 8 November 2011 (UTC)

To be honest, there are lots of good people in all religions. I've had bad experiences with unpleseant christians (who seemed to believe in the "join or go to hell" idea), but also with many grumpy religious people of other religions as well as atheists. To be honest, I don't think it's not so much that christians read the bible to mean "join us or be tortured for eternity", it's more that christians, especially fundamentalist christians, have a higher tendency to be intolerant of other religions and athiests. I agree that many more of the christians than of other religions that I've met, have been snobby and arrogant but they also display the "join or be tortured for eternity" act. Generalizing doesn't help here. Heck froze over (talk) 04:05, 10 November 2011 (UTC)

This suggests to me that the communication is pure idea, not sound or direct sensory experience. ~AH1 ^(discuss!) 03:25, 9 November 2011 (UTC)

How do you reckon? Plasmic Physics (talk) 04:10, 9 November 2011 (UTC)

What do I reckon? I reckon that this thread belongs in Science, and the post below about destroying the Vatican belongs in Humanities. ~AH1 ^(discuss!) 00:27, 10 November 2011 (UTC)

To answer the original question (as opposed to the question of who is more intolerant out of atheists and christians), we need to make a few assumptions. As Jayron32 pointed out, this question is very hard to answer if we accept that communication with god is possible. (For simplicity, I'm going to adopt the convention in this thread and assume that "god" refers to the christian god.) One assumption is that there is no god. If you find that offensive, simply assume that god wouldn't lie to us. This shouldn't be a problem as I think it's fair to say that the vast majority of christians make this assumption. Therefore, we can all talk about people who are factually wrong (doomsday predictors etc.) and people whose messages disagree with established scripture (if christians thought that scripture could be updated, they would be muslims and mormons.)

Another catergory of people who are clearly not talking to god is the christian psychic. I think it's fair to say that genuine godly communication should be distinguishable from cold reading, or similar techniques used by regular psychics. Since cold reading is a learned skill and secret radio equipment etc. is hard to use accidentally, a reasonable conclusion is that these people's only mental illness is a complete disregard for others and a willingness to manipulate people for personal gain. Relevant material can be found in Antisocial personality disorder.Teshmanesh (talk) 12:29, 10 November 2011 (UTC)

I'm not intolerant, I tolerate other religions, that doesn't mean that I respect them, I do respect the people though. You don't win friends when you're being a jerk to them. Plasmic Physics (talk) 19:43, 10 November 2011 (UTC)

This discussion has ranged far and wide, but there's still nothing here to disprove the interventions of an omnipotent being, who can cover his tracks. Or even very powerful beings. You still have no idea whether you're on the Star Trek Holodeck in a recreation of the early 21st century (which as the earliest time with an extensive video record, is indeed a very popular candidate for simulations, though I think this one contains some pretty egregious errors due to an uncritical acceptance of government and corporate identity databases which were largely despised and frequently subverted by the original Terrans)

Commenting on whether a behavior at this fundamental level of belief is "sane" or "rational" is likewise spitting into the wind - you're evaluating this relative to what? A person has to appeal to some standard of sense or reason, ultimately, really, morality to make such assertions, which in effect begs the question. Is a Nazi atheist rational for trying to make his race survive at the expense of all others? (Who said survival, whether on an individual or on a racial level, is the worthy purpose to follow?) There's just no standard for comparison; the statement ultimately is meaningless. Wnt (talk) 05:14, 11 November 2011 (UTC)

It's a fact of life and logic that anyone can ask "why" until ANY statement becomes ultimately meaningless. But somehow we all manage to cope. This is where appeals to empiricism come in: if a model works, it's right (not right in the strong sense of the word. Just right enough to be useful.) The principles of logic and reason are what allow us to do anything, and the more rigorously we've defined them, the better results we get. The same general principles that led us to having this discussion in this format are the same principles that make me skeptical of a god, or a holodeck.

Given that this is the science desk, and the null hypothesis (that there is a god who has any effect on the universe) has yet to be discounted, I suggest we continue as if god does not exist. Teshmanesh (talk) 10:19, 11 November 2011 (UTC)

Historical choice of "positive" and "negative" charge in the one-fluid theory of electricity

Was the choice of the type of charge to be call "positive" entirely arbitrary?

Electric charge#History briefly describes how early natural philosophers witnessed the triboelectric effect in which, when two types of material were rubbed, one (such as glass) built up a certain type of charge which we now call "positive" (but was called "vitreous electricity" during the time of the two-fluid theory of electricity), and the other built up another type of charge which we now call "negative" (but was then called "resinous electricity"). Benjamin Franklin and William Watson independently proposed that the two types of electricity were actually a surplus or deficiency of a single electrical fluid -- a positive or negative pressure. Clearly they chose "vitreous electricity" as that fluid, but the articles do not indicate why. Was the choice purely arbitrary on their part (and if so, did they state this) or was there some reason to suspect that the one true fluid was vitreous and not resinous? -- 49.228.87.218 (talk) 01:47, 7 November 2011 (UTC)

I'm pretty sure they assigned the "+" charge to the "fluid"; thus more of it would be more + and less of it would then be -. I'm not sure they "chose" the vitreous fluid specifically to make positive; I think Franklin and Watson concieved of a single electric fluid which there was either too much of or too little of. This coincidentally gives the same "sign" as that of the vitreous fluid, but that's a coincidence, and wasn't part of Franklin and Watson's thinking here. --Jayron32 01:52, 7 November 2011 (UTC)

When rubbed with fur, glass tends to lose electrons, and become vitreously electric (positively charged), amber tends to gain electrons and become resinously electric (negatively charged). Plasmic Physics (talk) 01:56, 7 November 2011 (UTC)

Yes, but that does not change the fact that there are two theories being explained above, and the first does not necessarily influence the second. There is a "two fluid" theory: Whichever of the two fluids that was in excess determines the charge of the substance. There is a "one fluid" theory: an excess or deficit of that fluid determines the charge. The + and - convention was created by people who adhered to the "one fluid" theory, which is why + merely means an "excess" of that fluid. The convention got carried through to the modern theory, which is how the modern particles (electrons and protons) got assigned their charges. --Jayron32 02:06, 7 November 2011 (UTC)

But Franklin and Watson were certainly aware of the behavior of both glass and amber, and for some reason they chose the charge that built up on glass as the positive one. If this choice was in fact arbitrary, weren't they intelligent enough to recognized that fact and honest enough to state it? If it was not entirely arbitrary, did they write of why they made the choice they did? For instance, perhaps the charge they were able to build up on glass was significantly stronger than what they could build up on amber. -- 49.228.87.218 (talk) 02:31, 7 November 2011 (UTC)

Might be enlightening to this discussion to go read what Franklin himself had to say about the terminiology in his Experiments and Observations on Electricity, pub. 1769. From the second letter in that book, on page 8, dated 1747: "Hence have arisen some new terms among us: we say, B is electrised positively; A negatively. Or rather, B is electrised plus; A, minus. . . ." That's as far as I got, and I'm not a scientist, but he refers to the two charges many more times in subsequent passages of the book. Textorus (talk) 03:48, 7 November 2011 (UTC)

You're awesome! That is exactly the sort of reference I was seeking. I'll write back after I've read through it all. (It might be a while.) -- 49.228.87.218 (talk) 04:18, 7 November 2011 (UTC)

Glad I could help. Textorus (talk) 04:37, 7 November 2011 (UTC)

I don't know what Franklin wrote about it, but I do know that the choice was indeed completely arbitrary. Dauto (talk) 15:37, 7 November 2011 (UTC)

The end result ends up being arbitrary, but that doesn't mean that Franklin's rationale at the time he came up with the convention was arbitrary to him. He may have believed his choices made sense specifically, even if they don't today. --Jayron32 15:40, 7 November 2011 (UTC)

That is possible, of course, but I imagine he would have been smart enough to realize it was an arbitrary choice, even if he didn't specifically state that somewhere in his writings. Dauto (talk) 16:08, 7 November 2011 (UTC)

Not completely arbitrary. Negative charges move more easily in certain situations than positive ones, even concerning the triboelectric effect. It's a common school experiment I think, though I forget the exact setup. I think it involves the ground.... but I can't remember what exactly is done to distinguish the two. elle _{vécut heureuse} ^{à jamais} (be free) 16:20, 7 November 2011 (UTC)

Also, negative lightning is different from positive lightning, which one would imagine Franklin had a bit of experience with. "An average bolt of positive lightning carries an electric current of about 300 kA — about 10 times that of negative lightning." (From lightning.) elle _{vécut heureuse} ^{à jamais} (be free) 16:26, 7 November 2011 (UTC)

Though past the heyday of alchemy, it might possibly have had a few things to contribute. (Didn't they pioneer a primitive form of electroplating?) And there was the heyday of animal magnetism too. Maybe positive charges were regarded as "positive" for the health. And wouldn't people have noticed at some point that sparks for really large potential differences (where you could actually watch it happen) that it always flowed from negative to positive? Maybe "positive" attracted sparks. You have things like Van de Graaff generators after all. (From the article: "The fundamental idea for the friction machine as high-voltage supply, using electrostatic influence to charge rotating disk or belt can be traced back to the 17th century or even before.") At some point, people would have noticed that direction really did matter. elle _{vécut heureuse} ^{à jamais} (be free) 16:39, 7 November 2011 (UTC)

Finally, from electrostatic generator may provide your answer: In 1785, N. Rouland constructed a silk belted machine which rubbed two grounded hare fur covered tubes. Edward Nairne developed an electrostatic generator for medical purposes in 1787 which had the ability to generate either positive or negative electricity, the first named being collected from the prime conductor carrying the collecting points and the second from another prime conductor carrying the friction pad. elle _{vécut heureuse} ^{à jamais} (be free) 16:46, 7 November 2011 (UTC)

Yes, as you have pointed out there are many ways to tell the positive and negative charges apart. But none of that makes the choice of which one is positive and which one is negative less arbitrary. Dauto (talk) 18:26, 7 November 2011 (UTC)

I think you're reading the arbitrariness too ahistorically. Under our modern understanding of charge, calling them one or the other is indeed arbitrary.

As Jayron points out earlier, Franklin (in some contexts, anyway) saw electrical charge as a subtle fluid, and considered that the building up of the fluid made something positive, and being deficient of it made one negative. So for him it wouldn't have been an arbitrary labeling of the charge — it would have been a measure if one had an abundance of the fluid (and thus were in the positive side of a balance) or in the detriment of it (and thus a negative). In his case they aren't arbitrary labelings, but metaphors for understanding the mechanism behind them (probably from the domain of accounting or commerce — something like a balance of the charge).

Of course, we now know considerably more about charge and can say with confidence it doesn't quite work that way, but that's a very different theoretical regime than Franklin was using. He was a smart guy, but he was not thinking about it in the same way we were. For him they aren't arbitrary terms. (A similar issue is found in considering the title of a biological cell — you could call them whatever, but Hooke gave them that name for non-arbitrary reasons.) --Mr.98 (talk) 21:00, 7 November 2011 (UTC)

He must have known that there was no way to tell which one was positive and which one was negative irregardless of his understanding (or lack of it) so he arbitrarily chose one to be positive. He was smart enough to know that that choice was arbitrary. Dauto (talk) 21:07, 7 November 2011 (UTC)

But there were many subtle differences between the behaviour of positive and negative charges. Lightning would be a very good example. elle _{vécut heureuse} ^{à jamais} (be free) 23:44, 7 November 2011 (UTC)

Yes, there are subtle differences, but the choice of names - which one to call positive and which to call negative - is completely arbitrary and could vary well have gone the other way. It's arbitrary now and it was arbitrary at Franklin's time. The question is: did Franklin know that? Dauto (talk) 05:25, 8 November 2011 (UTC)

The clairvoyancy on display in this thread is truly breathtaking. All these folks who can't be bothered to quote what Franklin or anyone else actually had to say about the matter - but who are utterly, utterly certain they can read the old boy's mind when he's been mouldering in his grave for over 200 years . . . wow, that's quite a feat. Textorus (talk) 11:42, 8 November 2011 (UTC)

You must have misread the thread. Try again. Dauto (talk) 16:01, 8 November 2011 (UTC)

My reading skills are very good; the article thread is paved with "I think," "I believe," "I imagine." As well as a raft of assertions backed by no citations to reliable sources. It doesn't take a Ph.D. in physics to see that. In any case, the question is about the choice of a word, and who and why - not the physical properties the word describes. Textorus (talk) 17:49, 8 November 2011 (UTC)

You must have missed the disclaimer at the beginning of the side discussion, and I quote "I don't know what Franklin wrote about it". I never caimed I knew what Franklin said or knew. I'm just pointing out that from physical principles the choice cannot have been anything other than arbitrary. Dauto (talk) 18:16, 8 November 2011 (UTC)

OP here (finally logged in). Respectfully Dauto, I believe that you are wrong. Yes, by today's understanding of electricity the choice of positive and negative is entirely arbitrary, but Franklin and Watson's single fluid theory is not the same as our modern understanding (which in some ways should be considered a mix of the two preceding theories). It was not a matter of Franklin naming one type of charge negative and the other positive. His theory posited a single type of charge, and he did attempt to determine the direction of motion of that charge in various triboelectric experiments and he came to the wrong conclusion, deciding -- based on evidence -- that the charge which built up on a piece of glass was due to a surplus of charge carriers ("electric fire" or "electric fluid") and thus called it positive. (We now know that the charge is due to a deficit of electrons -- the moving charge carriers.)

In Franklin's model, all matter was permeated with very fine pores (too fine to absorb air or water) which attracted electric fluid much as a sponge "will naturally attract and absorb" water. A material in its "natural state" contained exactly enough electric fluid to fill these pores and exhibited no "electric atmosphere". Any additional electric fluid added must then build up on the surface and create an "electric atmosphere". Conversely, removing electric fluid left the internal pores empty, and their natural affinity for the electric fluid created an electric atmosphere of the opposite polarity.

In his early letters he seems to take for granted that the triboelectric charge which builds up on glass was due to an excess of electric fluid. In February 1752 [Letter VII / p 99 / PDF p 128], Ebenezer Kinnersley wrote to Franklin, describing an experiment using both sulphur and glass spheres which built up opposite charges, stating that it was unclear which direction the "electric fire" was running in each, and offering to lend a sulphur sphere to Franklin in hopes that he could "discover some method of determining which it is that charges positively". On March 2 [Letter IX / p 102 / PDF p 131], Franklin acknowledged receipt of the brimstone sphere, and said that, while he had not yet gotten the experiment working, he doubted Kinnersley's results, suspecting "that the different attractions and repulsions you observed, proceeded rather from the greater or smaller quantities of the fire you obtained from different bodies, than from its being of a different kind, or having a different direction." Two weeks later [Letter X / p 103 / PDF p 132], Franklin wrote that he was "agreeably surprised" to have successfully replicated Kinnersley's work, and put forward the belief that it is "the glass globe that charges positively, and the sulphur negatively" primarily because the charge which built up on the glass was stronger than that which built up on the sulpher, stating that "bodies of a certain bigness cannot so easily part with a quantity of electrical fluid they have and hold attracted within their substance, as they can receive an additional quantity upon their surface by way of atmosphere. Therefore so much cannot be drawn out of the conductor, as can be thrown on it." But he does add that "these are hasty thoughts". He is still not entirely convinced a year and a half later when he wrote to Peter Collinson [LETTER XII / September 1753 / p 113 / PDF p 142] asking that he "recommend it to the curious in this branch of natural philosophy, to repeat with care and accurate observation, the experiments I have reported in this and former papers relating to positive and negative electricity, with such other relative ones as shall occur to them, that it may be certainly known whether the electricity communicated by a glass globe, be really positive."

That is as far as I've gotten, even just skimming. Between the long s, ct ligatures, and inconsistent scanning quality, the manuscript (thanks again, Textorus) is a slow read, and the ePub has a fair number of OCR errors. There is more to this story (including an apparent disagreement with Watson about the direction of charge flow) and I'll report here again after perusing the work. I close with this Franklin gem [p62 PDF p 91].

Nor is it of much importance to us, to know the manner in which nature executes her laws; 'tfs enough if we know the laws themselves. 'Tis of real use to know that china left in the air unsupported will fall and break; but how it comes to fall, and why it breaks, are matters of speculation. 'Tis a pleasure indeed to know them, but we can preserve our china without it.

-- ToE^T 00:27, 9 November 2011 (UTC)

That is a very good description, thank you. I've briefly skimmed the book some further. Letters are not in the strict chronological order. There is some discussion on the nature of electricity in the lightning, other properties of electricity, a few letters discussing relationship between electricity and electromagnetism. There are long sections which are not concerned with electricity at all - in one, Franklin and his correspondents go at length about things like demographics of American colonies, water spouts, whirlwinds, and effects of mountain ranges on climate. Starting page 284, we have 35 pages describing a novel fireplace design of Franklin's invention, including instructions to the prospective bricklayer such as ".. if this air-passage be so situated as that mice may enter it, and nestle in the hollow, a little grate of wire will keep them out."

Things get back on the subject of electricity around page 390 with some letters dated 1761-62. I don't see him questioning the identification of positive/negative charge. But, on page 407, there is an interesting discussion that shows how little he really understood electricity even at that time. His correspondent proposes that similar electric charges repel and opposite electric charges attract. Franklin counters that there is no evidence for attraction between opposite charges, and proposes instead that "the electric fluid is attracted strongly by all other matter that we know of, while the parts of that fluid mutually repel each other"! Then the book drifts away from the subject of electricity again, and any subsequent references to electricity are only made with regard to the lightning.

It seems to me that he never got around to rechecking that subject - and, even if he did, his equipment was too crude to make correct conclusions. (In his case, the correct conclusion would be that he is physically incapable of determining which charge is positive and which one is negative, because they are symmetrical for all practical purposes. It took until 1890's to determine the sign of the elementary charge carrier.) He started with his original assumption that rubbing the glass imparts a positive charge onto the glass. There is a statement on page 6 regarding experiments "demonstrating" "afflux and efflux" of electrical charge onto and off the electrical sphere - he found some years later later that those experiments demonstrated no such thing, but, by then, the choice was made. Then in 1752-53 he may have tried to reconsider the choice, but results were not decisive enough to redefine positive negative and vice versa.--Itinerant1 (talk) 01:58, 9 November 2011 (UTC)

Vin de Borgia

What substance(s) were the Borgias known/believed to use to poison their rivals? 67.169.177.176 (talk) 02:56, 7 November 2011 (UTC)

Arsenic, according to the second paragraph of the House of Borgia article. Red Act (talk) 03:22, 7 November 2011 (UTC)

Interesting... Was there an antidote for it at that time? 67.169.177.176 (talk) 01:50, 8 November 2011 (UTC)

I don't believe there is an antidote even now that would save you from a single dose of such strength that it could kill an adult human. Most treatments for arsenic poisoning take more time than a person who had ingested such a dose has left. However, according to the article on it, " Dimercaprol and dimercaptosuccinic acid are chelating agents which sequester the arsenic away from blood proteins and are used in treating acute arsenic poisoning. " Doesn't sound like something they would have had 500 years ago. Beeblebrox (talk) 05:40, 8 November 2011 (UTC)

What about concentrated garlic extract? That stuff contains lots of thiols and other sulfur compounds that also can chelate the arsenic right out of the victim's body (although not as effectively as BAL, to be sure). 67.169.177.176 (talk) 05:53, 8 November 2011 (UTC)

I wouldn't attempt that at home if I were you. Textorus (talk) 12:54, 8 November 2011 (UTC)

Neither would I. 67.169.177.176 (talk) 05:24, 9 November 2011 (UTC)

cotton balls

our cotton balls for facial use washed in a factory to remove the pesticide? — Preceding unsigned comment added by 92.48.194.147 (talk) 15:25, 7 November 2011 (UTC)

Yes, they are washed for sterility, which is very intensive and should remove most if not all pesticide residue. 67.6.136.218 (talk) 17:18, 7 November 2011 (UTC)

calculating the entropy of dissociation for an ideal gas

The entropy of expansion for a gas is +nR(ln V2/V1). What is the entropy of dissociation for an diatomic ideal gas for the reaction XX <----> X-X? (We could also add this to our articles on dissociation)?

Phase changes and dissociations have a molar entropy value, but it seems to me that from stat mech molar entropy for a dissociation would not be constant....or would it? elle _{vécut heureuse} ^{à jamais} (be free) 15:35, 7 November 2011 (UTC)

If we have N molecules of X_2 in a volume of V, then the entropy increase if they all dissociate is:

$\Delta S=Nk\left[{\frac {3}{2}}-{\frac {7}{2}}\log(2)+{\frac {1}{2}}\log \left({\frac {m^{3}kT}{2\pi h^{2}I^{2}n^{2}}}\right)\right]$

where n = N/V is the number density of X_2, I is the moment of intertia of the X_2 molecule, and m is the mass of a single X atom. This is assuming that vibrational modes are not excited (as is usually the case around room temperature). Count Iblis (talk) 18:15, 7 November 2011 (UTC)

Hmm, I meant to examine iodine, actually, whose vibrational transition temperature occurs at 307K. But thanks! How would I examine molar change in entropy, say, if there were only partial dissociation? I basically was thinking of a value in J/(mol*K). elle _{vécut heureuse} ^{à jamais} (be free) 23:46, 7 November 2011 (UTC)

added insulation

my previous question was archived so I'm posting again

I had extra cellulose insulation blowing into my attic Several years ago. I think I have a roof leak. How am I supposed to go into the attic or have a contractor go into the attic to find the leak, without them stepping on the insulation compressing it and how are they supposed to see the studs to walk on. — Preceding unsigned comment added by 92.48.194.153 (talk) 15:18, 4 November 2011 (UTC) Contact a reputable contractor who does this sort of work all the time, and comes with a stellar reputation and good recommendations. Not to be blunt, but someone who does this sort of thing all the time should be able to deal with your situation, through experience and knowledge. In other words, while you may not be able to see how to get around the problem, I would trust someone who deals with the problem all the time to know what they are doing. --Jayron32 16:51, 4 November 2011 (UTC) I doubt if the contractor would care if they compress the insulation. As for finding the studs, he'd start at the opening to the attic, and feel around for them, then follow the ones he finds. Eventually he would be able to predict where the rest were. If he was going to spend any amount of time up there, he would likely put down some walkways over the insulation and across the studs. Yes, this would compress the insulation more, but he wouldn't care about that. StuRat (talk) 21:19, 4 November 2011 (UTC) Waterlogged insulation is unlikely to be very effective anyway, so I would deal with the more pressing issue (the leak) first. --Colapeninsula (talk) 12:02, 7 November 2011 (UTC)

okay is there anyway I can go up in the attic and look around without compressing the insulation? — Preceding unsigned comment added by 92.48.194.178 (talk) 15:48, 7 November 2011 (UTC)

Heh, I saw a plumber use an endoscope recently. Of course, if you call a plumber for a roof leak people might say you're nuts. ;) Wnt (talk) 16:03, 7 November 2011 (UTC)

Probably not without compressing it somewhat, no. But, if you are careful to always step in the same few spots, then you can minimize the compression. But really, even if you went up there and intentionally compressed all the insulation you could, I bet your energy bill would only go up maybe 1%, which is silly to worry about compared with how much water damage could cost you. Just don't worry about it. Or, if you wish, have some more insulation blown in after the leak has been fixed. StuRat (talk) 16:09, 7 November 2011 (UTC)

A thin stick or a stiff wire will let you probe enough to find the framing without un-fluffing the insulation. In principle, the framing should be regular, either 16" or 24" apart. If the roof is of truss construction, the framing will be obvious, as the trusses will emerge from the insulation. If it's blown in, you can still fluff it as you retreat. Acroterion (talk) 20:08, 7 November 2011 (UTC)

Note that there are various kinds of cellulose insulation. In most cases the adverse effects from stepping on it a few times would be minimal. If you are planning to go in ther yourself I strongly recommend that you wear a dust mask or respirator, that stuff is not something you want to be breathing in, and any disturbance at all will stir it into the air, especially in such an enclosed space. Beeblebrox (talk) 05:23, 8 November 2011 (UTC)

I had a house with an attic which had cellulose blown in over the joists, which were out of sight below the surface of the insulation. I found it easy enough to walk along a joist, shuffling along with the feet on the joist, and displacing rather than stepping down on the fluff. It pretty well fell back into place behind the feet. There is a very real risk of missing the joist and stepping or falling through the ceiling, more so if one is lifting the feet up and stomping down rather than following the joist with the feet. Edison (talk) 15:21, 8 November 2011 (UTC)

Turning our sun into a black hole

Lets say we turn out sun into a black hole. Would our planet orbit around it without any significant changes? How would the temperature change? I understand that the black hole would emit electromagnetic radiation due to Hawking Radiation, but I don't know how that compares to how much it emits right now, would a black hole emit more? 165.230.177.154 (talk) 17:07, 7 November 2011 (UTC)

No, much less. It would cool quickly with only the stored heat of the planet's core keeping surface temperatures barely above about 150 Kelvin. The planet would freeze solid and lifeless. 67.6.136.218 (talk) 17:16, 7 November 2011 (UTC)

The black hole (and its Hawking radiation) itself would be rather colder than the 3 Kelvin of the cosmic microwave background radiation.

In rough terms a black hole has to be lighter than the planet Mercury (or the moon) for its temperature to be higher than the microwave background. Jheald (talk) 17:52, 7 November 2011 (UTC)

And there would be no change to the planet's orbit (Assuming that the unknown process that created the BH did dot significantly disturbed the orbit). Dauto (talk) 18:17, 7 November 2011 (UTC)

You can calculate the temperature of a black body (such as a black hole) by its Blackbody radiation. A blackhole emits very little Blackbody radiation -- as someone pointed out, Hawking radiation is weaker than CMB. elle _{vécut heureuse} ^{à jamais} (be free) 23:49, 7 November 2011 (UTC)

Is the bowsprit considered a mast?

Resolved

To settle an argument with a sailing relative (I have no experience with sailing): apparently in France, the beaupré, or bowsprit, is considered a mast, so a three-masted ship is actually a two-mast ship with a bowsprit. He also argued this is internationally recognized. I honestly believe this is not the case. As can be seen at the French article for USS Constitution ([1]), the ship is categorized as a Trois-mâts. So what's the truth? Reflectionsinglass (talk) 19:43, 7 November 2011 (UTC)

This is purely a semantic argument? Then the proper course of action is to determine who is the authoritative source for sailing definitions. If, as your friend contends, there is an "international recognition" for some definition, somebody (or some agency) must actually have the authority to provide canonical definitions of terms, by decree. Which agency is that? Where does it publish its glossary of terms? If this question can't be answered, it's fair to settle the argument as "no standard definition exists," and various individuals may choose whichever definition they like. Nimur (talk) 19:53, 7 November 2011 (UTC)

It can be quite difficult to prove something does not exist, such as some existing but almost universally ignored "international recognition" on how to define and count ships' masts, as one can always argue that there might exist evidence one has not yet found. For what little my personal experience is worth: over some 50 years of reading English-language fiction and non-fiction, some of which has been about multiple-masted sailing vessels, I have only ever encountered "mast-counts" that exclude the bowsprit, and never encountered one that includes it. My guess is that an old salt is exerting traction on a landlubber's lower limb here. {The poster formerly known as 87.81.230.915} 90.197.66.220 (talk) 20:56, 7 November 2011 (UTC)

Google translate and french wiki page for "Trois-mâts" seem to be on your side. It says three masts vertical. Vespine (talk) 22:16, 7 November 2011 (UTC)

I concur with tpfka8829 and wish to add that bowsprits, as with masts and booms, are spars, but I have never heard of a vessel categorized by spar count. -- ToE^T 01:17, 8 November 2011 (UTC)

A quick look at Google Books produces some backup - Chapman Great Sailing Ships of the World By Otmar Schäuffelen shows a "3-masted staysail schooner" that has three masts AND a bowsprit. Alansplodge (talk) 10:06, 8 November 2011 (UTC)

Also, our Sail-plan article says "The standard terminology assumes three masts, from front to back, the fore-mast, main-mast and mizzen-mast. On ships with fewer than three masts, the tallest is the main-mast. Ships with more masts number them." Alansplodge (talk) 12:56, 8 November 2011 (UTC)

This is fantastic!! Thanks for all the responsesReflectionsinglass (talk) 18:19, 11 November 2011 (UTC)

Destroying the Vatican

Is the Vatican protected against rocket-propelled grenade attack? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 21:47, 7 November 2011 (UTC)

No, it would not be difficult for a group of people to sneak into the Vatican and launch a attack with heavy weapons. The recent attack by a group of militants in Kabul shows that you can't defend a city against such an attack.

You may also read about the military and police in the Vatican. Do you have a science reference question? Nimur (talk) 22:11, 7 November 2011 (UTC)

Can something really be protected against RPG fire? At some point, they will destroy the target. 88.9.210.187 (talk) 01:21, 8 November 2011 (UTC)

Two words for you: Reactive armor. 67.169.177.176 (talk) 01:52, 8 November 2011 (UTC)

A simple steel grill is effective against shaped charge weapons - it explodes the charge before it makes contact with anything substantial. This Ulster observation post is protected in this way, and this; but it wouldn't do much for the aesthetics of the architecture. Alansplodge (talk) 09:14, 8 November 2011 (UTC)

I don't know much about the subject but I'm not sure how that would work in the case 88 mentioned. Yes it may protect against the first few? (it seems one or two would be enough to me if you fire at the same location but this isn't something I know much about) charges but you're going to destroy the grid soon enough and then I don't see what's stopping you getting to the main structure. In other words, as 88 said, just keep attacking and you'll destroy it eventually. The grid may be effective if your concern is someone launching one or a few charges and then either running away or being killed. Nil Einne (talk) 10:23, 8 November 2011 (UTC)

Would that work to protect the Vatican? Our article suggests many current implementations are vunerable to being hit in the exact same location several times. As our article suggests, this likely to be difficult if you're hitting a moving tank which is likely to shoot back, unless your weapon fires 2 charges in rapid succeession, but if you're launching an attack against a stationary structure which doesn't shoot back I presume it's far less difficult. Nil Einne (talk) 10:28, 8 November 2011 (UTC)

Maybe after the first couple of rounds, someone might notice and do something about it. They're bloody noisy[2] and the Italian Carabinieri are famously armed to the teeth[3]. Anyhow, a 2.5kg warhead is not going to "destroy the Vatican" although it would do a lot of damage to a single room and its occupants. Alansplodge (talk) 11:19, 8 November 2011 (UTC)

I don't think anyone questioned that someone will notice, the question raised by 88 was more whether they'd be able to destroy the target (which I presume would be a specific structure, not necessarily a building but potentially just a statue or whatever, rather then the Vatican in the entirety) with enough firepower. The question of how plausible it would be for someone to sneak in and if they do, how long they will be able to continue their attack before they are killed or at least have to engage defenders is a distinct issue, relevant to considering what sort of defences you should build and how effective those defences may be, but not so relevant to the issue raised by 88 particularly if what you're suggesting will only defend against 10-20 RPGs (in other words, if we aren't talking about completely unrealistic possibilities like someone shooting the structure non stop for a few hours). (Although it's worth remembering as Nimur has pointed out, the recent Kabul attacks have highlighted the fact if someone does manage to bring in a fair amount of heavy weaponary, flushing them out isn't that simple even if you have ample firepower and training.) Nil Einne (talk) 14:12, 8 November 2011 (UTC)

I did not make that comment. The comment above mine was made by Count Iblis, who wishes to remain anonymous. The risk of misattribution was exactly why I fixed his unsigned comment in the first place. Nimur (talk) 16:51, 8 November 2011 (UTC)

These various armour types are designed to withstand a number of hits from a specified device; seven hits from a 7.62mm round in the same place, four hits from an RPG etc. To an extent that depends on the firer being able to hit the same place multiple times to breach the vehicle. An RPG isn't all that accurate.

There is also,l in the case of vehicles, a balance between armour defence and movement. A lighter armour may take fewer hits but the vehicle can get through or round obstructions more easily than a more heavily armoured vehicle. A V-shaped hull to defend against under-vehicle IEDs is of limited use against an IED constructed to fire into the side of the vehicle. A roller mounted out in front is fine against a pressure plate initiation immediately above the charge but of no use of it's a command wire or the charge is 8 feet ahead of the switch.

There is always a balance given the diversity of threats.

ALR (talk) 13:50, 8 November 2011 (UTC)

Er I don't get the relevance to vehicles here. Aren't we talking about whether reactive armour would provide much of a defence against a sustained attack by RPG fire on structures? This is what I thought we were discussing since 88 questioned whether it was realistic to protect the Vatican against sustained RPG attack and 67 suggested reactive armour was the answer. Nil Einne (talk) 14:16, 8 November 2011 (UTC)

RPGs are designed as anti-vehicle weapons and countermeasures are normally designed for vehicles; including stand-off armour, reactive armour, structural design etc. Essentially it's all context dependent.

ALR (talk) 14:31, 8 November 2011 (UTC)

The Vatican is protected by the Armor of God. Mitch Ames (talk)-

From a security planning perspective I'd turn that around and say what effect would a potential attacker want to have on the Vatican?

An RPG would be a "demonstration of vulnerability" attack, a media embarrassment as much as anything else. The volume of damage something like that could do is pretty limited as they're not all that accurate and don't pack a significant punch.

If one wanted to do some significant structural damage then a car-bomb would probably deliver more result, although I don't know anything about the geography so it may not be possible to get a car/ small van close enough to something structurally significant.

The debate about specific protection hinges around some of these issues, is it financially or architecturally viable to build in either adequate protection against a device? Given the age of the building you're then talking about either external blast netting or structural reinforcement. Since there is nothing visible, and no evidence of significant public works to reinforce then I'd suggest not. There are other defences that might be in play, including stand off distance controls and similar, but that probably needs local knowledge and a security planners eye to determine.

ALR (talk) 13:50, 8 November 2011 (UTC)

Agreed. Alansplodge (talk) 13:55, 8 November 2011 (UTC)

Has anyone considered the fact that the Vatican City is a dedicated place of peace, not a military stronghold? It is in fact (since 1970) one of the very few states that does not have any armed services (besides internal police). I do not believe they put much thought into defensiveness lately, and they probably have their reasons for that. Phebus333 (talk) 11:38, 10 November 2011 (UTC)

Could it be that the Italian army is the entity tasked with protecting the Vatican against external enemies? 67.169.177.176 (talk) 00:13, 11 November 2011 (UTC)

Schlick-Tweedie principle

This is a technique for balancing triple expansion steam engines. What is the principle?Okaha (talk) 22:23, 7 November 2011 (UTC)

In the Yarrow-Schlick-Tweedy system, the cranks of a four-crank engine are placed at angles such that a polygon with sides corresponding to the corresponding inertia forces will close.[4] On Wikipedia, the system is mentioned but not really explained in much detail at Steam engine#Multiple expansion engines and Compound engine#Marine applications. Red Act (talk) 00:07, 8 November 2011 (UTC)

I concur — Preceding unsigned comment added by 203.112.82.129 (talk) 01:54, 8 November 2011 (UTC)

FWIW we were taught this method of balancing engines at uni. It results in good first order balance if the crankshaft is short, but as the crank gets longer a rotating first order couple may prove troublesome. For a high speed engine you'll still need a proper dynamic balance as well. Greglocock (talk) 02:49, 8 November 2011 (UTC)

molar heat capacity of a black hole

Are we to assume that the molar heat capacity of a black hole (a property independent of mass though not density) is near-infinite? Say a supermassive black hole is strong enough to pull a very hot star into its sink. Where does all that heat energy go, if the black hole still remains at a few millionths of a degree Kelvin? elle _{vécut heureuse} ^{à jamais} (be free) 23:52, 7 November 2011 (UTC)

On an order of magnitude level, what would the molar heat capacity (per mol of some particle) be? Does the black hole just spin faster and faster? If the black hole is treated as a single particle... then wouldn't its heat capacity be some order of 5k/2 -- a very small number? (Or 7k/2, or corresponding as many modes as a black hole allows.) How does statistical mechanics work in black holes? elle _{vécut heureuse} ^{à jamais} (be free) 23:58, 7 November 2011 (UTC)

Note that the heat capacity of a black hole is negative -- as you add energy to a black hole it gets colder. (As in fact is the heat capacity for many other gravitating objects, such as stars -- see the references at Heat capacity#Negative heat capacity (stars) for some discussion about whether this is physically acceptable and/or what it means).

Statistical mechanics is still pretty tentative for black holes. On the one hand, the Hawking entropy formula that comes out of various semiclassical approximations seems to be pretty solid. This directly relates the entropy of the BH to its area, and from there you can get a formula for entropy as a function of the BH radius or BH mass. In principle this may very well be an entropy to which S = k log W can be applied, to get a density of microstates; but until there is a solid theory of quantum gravity, it is far from clear what those microstates actually are. Some calculations have been done based on some string theory models however, which apparently were thought to make some sort of sense.

Probably not appropriate to talk about a "molar" heat capacity, though, when a black hole is not made out of molecules. Jheald (talk) 00:17, 8 November 2011 (UTC)

The Earth is self-gravitating yes? Does it have a negative heat capacity too? (Ignoring its atmosphere.) elle _{vécut heureuse} ^{à jamais} (be free) 00:26, 8 November 2011 (UTC)

No, the Earth, unlike the sun has positive heat capacity. Dauto (talk) 05:18, 8 November 2011 (UTC)

But - and that's cool - An object in orbit around the Earth will accelerate when a braking force is applied and will brake when an accelerating force is applied. For instance, if you were in the shuttle and were trying to catch up to and dock with the space station that happened to be right ahead of you, you would fire the forward pointing jets (stepping on the brakes so to speak) and that would accelerate you forward. Dauto (talk) 05:37, 8 November 2011 (UTC)

Wait, what? --Jayron32 05:44, 8 November 2011 (UTC)

Yep. It's a consequence of the virial theorem by which you can see that if you provide negative work, the gravitational potential energy drops twice as much forcing the kinetic energy to increase. Dauto (talk) 06:02, 8 November 2011 (UTC)

That makes no sense. If I'm floating in orbit around earth next to another object, and I push on that object, it doesn't accelerate towards me! Can you explain how your scenario is different from that? --Jayron32 06:08, 8 November 2011 (UTC)

In other words, by removing energy, you go into a lower orbit effectively starting a Low Yo-Yo maneuver. Dauto (talk) 06:15, 8 November 2011 (UTC)

(EC) I think the procedure used to catch up with a spacecraft orbiting in front of you is generally more complicated than simply firing a single reverse thrust. But the basic idea is that firing a reverse thrust will lower the spacecraft's orbit, and lower orbits are faster than higher orbits, so to catch up to something in front of you, the first firing at least would counter-intuitively be a reverse thrust. See the second-to-last paragraph of Orbital mechanics#Rules of thumb. Red Act (talk) 06:20, 8 November 2011 (UTC)

See also that page that has a quote by Buzz Aldrin. Dauto (talk) 06:26, 8 November 2011 (UTC)

OK, thanks all. That sort of maneuvering is more complicated than Dauto made it sound. It makes sense when explained in the context of what ALL the steps in the manuever were, rather than simply "putting on the brakes makes you go faster". What is actually happening appears to be conservation of angular momentum which makes perfect sense; turning tighter orbit around the Earth will result in moving faster to maintain a constant angular momentum. When you decelerate, you reduce your kinetic energy, which means you drop into a tighter orbit around the earth, which makes you catch up faster to your target. When you are directly under your target, you then accelerate towards it, to move "out" from the earth into the higher orbit. Did I get all of that correct? --Jayron32 06:32, 8 November 2011 (UTC)

No, not correct. There is no angular momentum conservation here since the applied force causes a torque. Really, what happens is that you speed up because you go into a lower orbit when you brake. that's at the heart of the sun's negative heat capacity as well. Dauto (talk) 06:44, 8 November 2011 (UTC)

You go into a lower orbit when you break because you reduce your kinetic energy; this is the same reason that an electron drops into a lower energy level when it emits a photon, but on a classical rather than quantum level; do I at least have THAT part correct? (ignoring the angular momentum issue). --Jayron32 06:50, 8 November 2011 (UTC)

The lower orbit has higher kinetic energy. Dauto (talk) 06:58, 8 November 2011 (UTC)

Then why does "hitting the brakes" lower your orbit? I would think that lowering the orbit would require you to shed energy somehow, like an electron sheds energy in the form of photons. Can you perhaps explain how hitting the brakes causes you to gain energy? --Jayron32 07:16, 8 November 2011 (UTC)

You shed twice as much gravitational potential energy than the increase in kinetic energy (because of the virial theorem) for a net loss of energy. Dauto (talk) 07:23, 8 November 2011 (UTC)

My math sucks, but is that the 2<T> = n<Vtot> bit, where n = -1 since the Earth and the orbiting bodies are gravitationally bound? What you are saying is that equation means that increasing the T value causes the Vtot value to decrease by twice as much, due to the n = -1 for a gravitationally bound system. Did I get that correct? --Jayron32 07:29, 8 November 2011 (UTC)

Yes, that's it. So when you brake you lose energy, but even as you're losing energy you are also gaining kinetic energy because the loss in potential energy more than make up for the gain in kinetic energy, so you in fact speed up. Cool isn't it? That's also what happens to the particles in a cloud that eventually form a star. They lose energy by radiation and that forces them to gain kinetic energy warming the cloud up, hence the negative heat capacity. Dauto (talk) 07:37, 8 November 2011 (UTC)

Can I just point out for clarity that the word you want is "brake" (apply a stopping force), not "break" ([cause to] come apart). Also (less critically) "losing/lose", not "loosing/loose". AndrewWTaylor (talk) 17:32, 8 November 2011 (UTC)

Sorry about that. I fixed the mistakes. Dauto (talk) 18:09, 8 November 2011 (UTC)

(undent) Black holes violate most properties of physics, excluding gravity and possibly electromagnetism. That means values like temperature may not apply inside the event horizon, and in fact may travel out from the white hole on the other side. Some of the energy is excreted via bi-polar jets. ~AH1 ^(discuss!) 03:22, 9 November 2011 (UTC)

What's a mole of black holes? According to the no-hair theorem, the only thing I can think of is that a black hole is a single particle, so you mean 6x10^23 of them? --Trovatore (talk) 03:24, 9 November 2011 (UTC)

Yes' that's what he meant. Please note that the no-hair theorem is based on classical relativity and is likely invalid once quantum mechanics is taken into account. Quantum Gravity is a work in progress so it's hard to know for sure. Dauto (talk) 20:04, 9 November 2011 (UTC)