Wikipedia:Reference desk/Archives/Science/2006 September 2

Self CPR
I'm taking a final exam for an online class and one of the questions I have to answer is whether self CPR is fact or fiction.


 * Perhaps you could think about this for a few seconds. BenC7 01:58, 2 September 2006 (UTC)


 * If you are unconcious how would you do it?--Light current 02:03, 2 September 2006 (UTC)


 * There is a procedure to help yourself when you are choking where you hold your fists just south of your thorax and run into a wall with your head held back (I Canada you usually learn that as an aside on your way to becoming a life-guard). Maybe something similar could work for when your heart stops, though I think the chance of your heart stopping and you knowing while being concious are pretty much zero. Then there's the fact that manual CPR usually only works after repeated applications, which means you'd be running into the wall a lot. freshofftheufo  ΓΛĿЌ  06:27, 2 September 2006 (UTC)


 * ...That is a procedure in Canada? Can I PLEASE see it on tape or something? If I didn't suspect it would hurt like a bum, I'd try it out. Sounds difficult to run onto things like that. Henning 08:26, 2 September 2006 (UTC)
 * Haha, I've never actually seen it done. My instructor just explained how it could be done if you were ever caught by yourself with a chicken bone stuck in your throat. freshofftheufo  ΓΛĿЌ  15:57, 2 September 2006 (UTC)

Fiction. If you have no pulse and no respirations, you are unconscious and unable to do CPR. InvictaHOG 09:32, 2 September 2006 (UTC)


 * Which leads me to think, are you sure it's "self CPR" and not "self Heimlich-maneuver" or something? Just a thought. CptJoker 01:22, 3 September 2006 (UTC)

5 or 10 years ago there was a story which made the rounds of print media and internet that if one suddenly realized his heart had stopped, he could do self cpr by coughing vigorously, and get enough blood to circulate to maintain consciousness long enough to summon help or dial 911. A while letaer Red Crosss officials denied it was true. Could one realize the heart had stopped and still have consciousness for a bit? Why not? Edison 20:31, 2 September 2006 (UTC)


 * That's not to be done if your heart stops, it's taught in MedSchool if you go into VF. If you cough, at least some blood gets moved around cos the valves keep doin' what they're doin' despite zero cardiac output from ventricles. ≈Eh-Steve 21:02, 2 September 2006 (UTC)

Viral Marketing
I'm rather worried by the note at the bottom of the Factotum article. I wandered through the history, and apparently on 3 August, an anonymous person added what looked like a full-page advertisement for the film. On 23 August, another anonymous person removed it, leaving a rather cryptic note with a link to the viral marketing article. To be honest, I've been wondering for awhile just how much people could potentially take advantage of Wikipedia for monetary gain. Does it sound to you like that's what was happening? Black Carrot 02:16, 2 September 2006 (UTC)
 * Yes, it's absolutely a problem with a medium like Wikipedia. A simple example would be all the neologisms that people try to get added, thus increasing awareness about the unknown word in the hopes that somebody will actually get tricked into using it in an AOL chat session. Most of those get caught pretty easily, but I imagine it's much more difficult to pick things like that out of articles with corporate connections so who knows how much if it actually gets through. freshofftheufo  ΓΛĿЌ  06:33, 2 September 2006 (UTC)

When was redial invented?
I've been searching all over the Internet and I can't find the date that redial was invented. What I really want to know is, would telephones in 1990 have automatic redial buttons, and, if not, what would they have? Please help. 88.105.159.129 10:12, 2 September 2006 (UTC)


 * I would guess that was available on the first touch-tone phones. Dial phones did not normally have that feature. StuRat 10:24, 2 September 2006 (UTC)
 * True, but they had a line to the operator, who could probably redial for you--71.247.243.173 13:44, 2 September 2006 (UTC)
 * That would be a serious pain in the neck in comparison with just a simple button. --Fastfission 15:46, 2 September 2006 (UTC)

Ah, so it's been around since the sixties then. Thank you! 88.105.159.129 10:36, 2 September 2006 (UTC)


 * They've definitely been around since 1990. I can remember them from the even the very old (and crummy) phones from that time. --Fastfission 15:46, 2 September 2006 (UTC)


 * I have seen rotary phones with a redial function before. It's almost rediculously complex, and it seemed to take a while to actually dial the number (it of course has to mechanically spin the dial). I can't say when it was actually invented though, or if the touch-tone version came first. freshofftheufo  ΓΛĿЌ  15:55, 2 September 2006 (UTC)


 * Yea, I see no reason why it wouldn't be possible on a rotary phone, but it does seem like an ugly bit of machinery would have been required, making it easier to just manually redial. An analog audio tape of the clicks could also be recorded then played back.  A hybrid would also have been briefly possible, where the clicks were captured digitally and played back electronically.  Of course, once that technology was available, why not just upgrade to a touch-tone phone, instead ? StuRat 22:13, 2 September 2006 (UTC)
 * Have you ever tried redial on a dual-function phone? The kind with a tone switch, that can send rotary style signals if tone-dial doesn't work in your area (or at least I assume that's why). If it's set on rotary mode, and you hit redial, you can hear it clicking away old-skool, though I've never been interested enough to figure out how it was doing it (I've had at least 1 phone from the 80s with that capability). There's actually a manual rotary redialer featured in The Matrix. Guess they never thought of using an analog recording either. freshofftheufo  ΓΛĿЌ  10:22, 3 September 2006 (UTC)


 * You can't just tape record the sound of the clicks. Pulse dialing phones operate by momentarily opening the telephone circuit, blocking all current. The click you hear is just a side-effect of that (and, in fact, the dial has contacts that entirely or mostly mute the receiver while the dial is "off normal" (turned away from the normal position). And yes, some electronic dial-pulse phones did have "redial" capability. I had one that I'd guess dated from ca. 1980 or '85.


 * And then there were the card-dialing phones. Very odd, these devices (which dated from the '60s) contained a cute little card reader. By punching holes in plastic cards, you could program each card to contain one phone number. Then, by popping a person's card into the reader and pressing a single button, the phone read the card and dial-pulsed out the number, giving you the 1960s equivalent of speed-dial.


 * Atlant 01:15, 7 September 2006 (UTC)

Karl von Goebel
Why is Karl von Goebel sometimes known as Karl Ritter von Goebel and others as Karl Immanuel Eberhard von Goebel ? &mdash; Dunc|&#9786; 11:02, 2 September 2006 (UTC)
 * Check out Ritter. It is a title of nobility that can be added or not according to the author's preferences. Same goes for Karl von Goebel vs Karl Immanuel Eberhard von Goebel; it depends on context, space, and preferences. George W. Bush is sometimes referred to as George Bush or George Walker Bush or Dubya and Brian Eno is sometimes referred to as Brian Peter George St. Jean le Baptiste de la Salle Eno :). ---Sluzzelin 11:34, 2 September 2006 (UTC)

refrigerator vs. environment
Can a refrigerator operate successfully in an unheated garage in winter where the temperature falls below freezing?
 * Why not? Don't most firdges have an internal thermostat? in which case, it would read the temperature as below 0oC and woudln't need to do anything (: 71.247.243.173 13:43, 2 September 2006 (UTC)


 * if contents of a refrigerator spoil when power is cut off when the environment is warm ...obviously the fridge is not 100% insulated....therefore, if the fridge senses the outside temp. as freezing and doesn't do anything...wouldnt the contents eventually freeze? I am referring to a fridge...not a freezer.
 * There's no such thing as below zero ;). My guess would be that unless you had a fridge which had the ability to warm, then prolonged exposure to below zero would cause the contents to freeze. Hell, my fridge freezes everything in sight, and it has never seen temps below zero! --liquidGhoul 14:04, 2 September 2006 (UTC)


 * It gets colder than -20 C in the winter where I'm from, and the answer is a pretty obvious yes, if you go away on a ski trip for a few days and turn off all the power, all of the food in your fridge will freeze. freshofftheufo  ΓΛĿЌ  15:51, 2 September 2006 (UTC)

Soft drink machines are commonly outdoors in states where it gets to -20 F in the winter. I expect they have internal heaters to keep the contents from freezing. In an ordinary refrigerator, in an unheated garage, if the air got below 32 F for an extended perion the contents would certainly freeze. A little ingenuity could install an auxiliary thermostat inside to turn on the light bulb or a light bulb when the temperature in the fridge got down to 32 f. The deadband would have to be precise, so the light/heater would go off at a temperature below the one where the cooling unit went on, and contrariwise. For instance, the cooler goes on at a rise to 40 degrees and off at a drop to 37 degrees. The light bulb or heater goes on at a drop to 33 degrees and off at a rise to 35 degrees. See the problem? You could wind up with the heater on fighting the cooler. Edison 20:39, 2 September 2006 (UTC)


 * I expect they have internal heaters to keep the contents from freezing.


 * They do.


 * Atlant 01:03, 7 September 2006 (UTC)

If you had a small electric space heater, with a thermostat that goes down to freezing, you could put that in the fridge when it gets cold. Do they sell such heaters to keep pipes from freezing ? StuRat 22:00, 2 September 2006 (UTC)


 * I actually asked this question a few months ago. My suspicion, though I may be wrong, is that you guys may be off on the wrong track. From what I understand, refrigeration (as well as A/C) works by sucking in ambient air and passing it over coils of compressed freon. The freon coils are kept at a certain temperature (depending on the level at which the freon is compressed, the more compression, the colder). For a freezer, say, the freon is compressed to a point where it is below freezing, and air is then passed over them, causing below freezing temperature air to pass into the freezer, and thus causing the temperature of the air in the freezer to be below freezing temperature. For above freezing temperature refrigeration, the freon is less compressed, to a point where it is, say 1°C or 2°C. Ambient air is then blown over the coils, and the fridge temperature is lowered to just above freezing. NOW, when the temperature of the ambient air dips below freezing, the same thing happens. The below freezing temperature ambient air is sucked into the unit, blown over slightly above freezing temperature freon coils (1°C or 2°C), and thus, in a weird sort of way, the freezing ambient air is "heated up" to above freezing. I know it sounds weird, but when you think about it it makes sense. Heat doesn't always equal "fire" or "warmth" as we understand it. Think of it this way, throw a regular block of ice into a vat of liquid oxygen, and the ice cube will actually raise the temperature of the liquid oxygen. Throw a big enough block freezing cold ice in, and you may actually be able to heat up the liquid oxygen to its "boiling point" at which point it'll "boil" into oxygen gas. Of course, this is just one big guess, I could be wrong. Loomis 20:43, 3 September 2006 (UTC)

Seminar report
We have a weekly semianr to be given on any of the technological advancement aorund us. I have decided to give a seminar on the RADAR JAMMERS.

I was looking forward for some good materials so as to produce a good report. I have found a few but would like to get into the core of the subject for self interest.

Would be looking forward for help from any of u.. Thanks Saket--220.227.48.17 13:36, 2 September 2006 (UTC)


 * Doesn't it make sense for you to choose to give a seminar about something on which you are knowledgable, rather than just relying on the nice people at Wikipedia? &mdash; D a  niel  (‽)


 * electronic attack. Xcomradex 15:30, 2 September 2006 (UTC)

Memory Metal for Cars?
How strong are memory metals? Could you theoretically build the outside of a car from one, and then, after an accident heat it up and have it regain its former shape?

Thanks, &mdash; D a  niel  (‽) 14:43, 2 September 2006 (UTC)


 * I know this but I cant remember! I need to shape up I know 8-)--Light current 15:51, 2 September 2006 (UTC)

I don't understand why it's so expensive to replace a car body panel. They should be dirt cheap, as they're stamped by the thousand. Perhaps we need a change in the structure of auto sales, where the car company leases cars for a few months at a time. Then, when they get a dented car back, they would have an incentive to replace the body panel cheaply, so it could be released. At present, they don't seem to have any incentive to make repairs inexpensive, as that just prevents people from buying new cars. StuRat 21:53, 2 September 2006 (UTC)


 * A great question! BenC7 04:09, 3 September 2006 (UTC)


 * The price could have someting to do with labour intensity. The panel seems expensive compared to the car, but it's really the cars that are dirt cheap for the sort of product you get, due to mass production. Repair work isn't mass production, so it's relatively expensive. Maybe if you could buy the panel and then replace it yourself. But then there would have to be a distribution network for loose parts, and the per piece price would probably far exceed the production cost. Your solution would solve the latter problem, but not the former. DirkvdM 05:59, 3 September 2006 (UTC)


 * The existing distribution channels for dealer parts could also be used for car body panels. Each dealer could stock several of each body panel for each car model. StuRat 11:47, 3 September 2006 (UTC)


 * There is also the possibility of plastic car exteriors, which I believe would be easier to 'de-dent' and would also be lighter and therefore more fuel efficient. This already exists, but my guess it isn't popular because plastic can't be made as shiny as metal. DirkvdM 06:01, 3 September 2006 (UTC)


 * Although (at least for most cars) it's not the metal that's doing the shining, it's the half centimeter coat of crap on top of it that does. You may be partly right, though, that it seems to be more difficult to "buff" plastics smooth, which could cause problems before you coat them with the shiny stuff. freshofftheufo  ΓΛĿЌ  10:14, 3 September 2006 (UTC)


 * Plastic body panels are actually significantly more expensive than sheet metal. They have the advantage of being lighter, but aren't strong enough for a unibody design, requiring a frame.  The tend to crack when damaged, not dent, which makes them more difficult to repair.  For these reasons, they tend to only be used on expensive sports cars, like the Chevrolet Corvette. StuRat 11:42, 3 September 2006 (UTC)

Special relativity
So, I've been reading into Photon, Special Relativity and more, and I have come to be frustrated, very at that, at not understanding the topic.

I realize very well that there is a particle-wave duality to photons, it's their speed I can't understand. If I travel on a pimped up spacecraft with neon lights all over, and overtake another spacecraft, I will measure the speed of HIS light as C, even though I am travelling at +V away from him and his light?

Oh, and I have a second question, way better! Is there any book like... Relativity/Quantum dynamics For Dummies, which actually explains everything? Everything with a capital E, that is polarization, QED, string theory, t... everything? Many thanks in advance. 81.93.102.35 14:59, 2 September 2006 (UTC)


 * (I am not qualified to answer, don't get annoyed at me) As far as I know, you are right. Whatever speed you are traveling towards/away from each other, you will still see the speed of light in a vacuum at the same. This, I think, arises from some weird curvature of spacetime. &mdash; D a  niel  (‽) 15:22, 2 September 2006 (UTC)


 * THe way I tend to think of it is that light can only travel at one speed (in vacuum). THis speed cannot be changed as it is a function of the fundamental properties of space. So, whenever you try to measure the speed, you always get the same answer. What you will see, however, is a red shift if you are travelling away from the light source and a blue shift if travelling towards it. Is this helpful?--Light current 15:40, 2 September 2006 (UTC)


 * Though the "...for Dummies" franchise doesn't seem to have given it a shot yet, this google search might help you find the same sort of introductions. freshofftheufo  ΓΛĿЌ  15:48, 2 September 2006 (UTC)


 * List of ...for Dummies books does mention Einstein for Dummies! Until you get the book you can also try more googling, the first hit looks like something I'm going to go and read right now. Weregerbil 16:07, 2 September 2006 (UTC)


 * For future reference: Most of the parameters in a Google URL are unnecessary (and possibly undesirable for a user whose cookie has unusual preferences); all you really need is the "q=". Weregerbil gets it right.  &mdash;Tamfang 18:26, 2 September 2006 (UTC)
 * Yes, I noticed that and I was wondering what effect the "firefox" parameter generated from my browser would have on non-firefox users. I was just being lazy anyways, I'll make my links shorter in future! freshofftheufo  ΓΛĿЌ  10:09, 3 September 2006 (UTC)


 * The Road to Reality by Roger Penrose is your best bet for a book that explains everything. Light current's comment that the speed of light cannot change might not be entirely accurate.  There is evidence that the speed of light was lower in the past.

'Moving' source, 'stationary' observer
Look at it this way. Assume you are 'stationary', and something is receding from you shining its light at you. When the light on the distant object leaves the lamp, the light doesnt know that the lamp is travelling backwards at high velocity. All it knows is that it has been launched into space and is therfore compelled to travel at the universal velocity 'c'. When you measure its spedd you find its 'c' also. Any clearer?--Light current 15:49, 2 September 2006 (UTC)

'Stationary' source, 'moving' observer
Essentially the same as above. THe source transmits the light at 'c'. Although you are moving backwards at high velocity, the light doesnt know this and doesnt care. When it reaches you, red shifted, you still measure its velocity as 'c'--Light current 16:16, 2 September 2006 (UTC)

An easier answer (or so I hope)
Ok, you're watching another spaceship full of neon lights and you're observing it's light. You're travelling away from the other ship with a velocity of V or something of the like, something pretty fast. The other ship will fall behind you pretty fast. But if you phone the guys in the ship, they'll tell you: "We aren't moving, it's you that's going away." Well, that's just a different point of view, you see? Nothing special. Velocities just seem to be different when you're moving.

Except the one of light. The guys in the other space ship aren't moving (or so they think), so when they observe their neon lamps, they'll see light coming out with a velocity of c. When you are observing this same light being in the other ship, you'll see the same velocity relative to your own position. That may seem weird – you'd think it should be c+V or c-V or something of the like. But it doesn't work that way.

To relate your observation with their observation, you need Lorentz transformation. This means that space and time are related to each other in a way which is slightly more complicated than how you'd think they are. Velocity being space divided by time, it gets quite more complicated than c+V. But the result is just c.

Hopefully this helps. David 16:42, 2 September 2006 (UTC)


 * But surely the Lorenz transformation is a consequence of the invariance of the speed of light, and not the other way round? So the answer should be able to be given without bringing in Lorenz? 8-|--Light current 17:55, 2 September 2006 (UTC)


 * Thank you for clearing this up for me. I am in the process of reading that -- for Dummies-thing, it should work wonders. :) 81.93.102.35 18:10, 2 September 2006 (UTC)


 * Good page: Velocity_addition_formula--Light current 18:11, 2 September 2006 (UTC)


 * I know that according to the Michaelson/Morely experiment, there isn't any detectable change of speed of light in any direction, so there is no basis for an ether to exist. Still, have anyone tried accelerating something in vacuum? I don't know how realistic it is to assume that this can make any difference - I just wondered if it is certain that nothing spends more time or energy accelerating into one direction than into another. 81.93.102.35 19:27, 2 September 2006 (UTC)

Try The Elegant Universe by Brian Green. It starts with a humorous discussion of classical physics including relativity and progresses through quantum and finally string theory. He does not use any math so its a good book for light reading

129.174.194.48 18:01, 6 September 2006 (UTC)

Infinitly improbable events in infinite time
In an infinate amount of time, the probability of any event happening which has a probability not equal to zero is 1. So in infinite time every event even with a miniscule probability of say the inverse of a googel to the power of a googel, will definitely happen.

So even after I'm dead, by random chance something resembling my brain with the same thoughts and memories as I have now must eventually come into existence, not only once but many times. And I could also have the same kind of body, the same kind of society even. In other words I (and you) should be resaurected (sp?) many times, if the universe lasts an infinite length of time.

Can anyone point out a logical flaw in the above argument please? For example, will the universe last an infinite amount of time?


 * The universe (as we know it Jim) will not last an infinite time.--Light current 17:57, 2 September 2006 (UTC)


 * Although assuming our universe could last for an infinate time, i don't see any flaws in your argument. Benbread 17:58, 2 September 2006 (UTC)


 * In case anyone hasn't seen it: Kolmogorov's zero-one law. Melchoir 18:03, 2 September 2006 (UTC)


 * Many events (as humans perceive them) that do occur do not simply have miniscule probablity, they actually have probability of exactly 0. If the probability of an event is 0, then even given infinite time, then you might still observe that it happens never, only once, or many times.  Consider a dart board and a dart.  The dart board has some finite area.  The dart has a much smaller, but still finite cross-section; however one can think about the center point of the dart: some mathematical point that defines the true center of where the dart strikes.  Such a point has no area, being just a point.  Throw the dart at the board and you know that some point will be selected in this way, but there are an infinite number of choices and each time you select only one center point of the dart.  Hence the probability of selecting any particular point is 1/infinity which is exactly equal to 0.  And yet you can perform the action and know each time with certainty that some point will be selected.  Further, an event with a probability of 1/infinity, given an infinite number of trials, need not be expected to occur, because infinities come in different degrees, countable and uncountable.  By definition any repetitive action performed an infinite number of times belong to the countable class of inifinities because you can enumerate each trial (1, 2, 3, 4, etc.).  However, it can be proven that you could never enumerate all the points on a dart board, no matter how clever your scheme might be, there are simply vastly more than could ever be described by the set of all numbers 1, 2, 3...  This is non-intuitive, I know, but in many situations there are simply more possible outcomes then one could possibly precisely enumerate, even given infinite time to do so.  I supsect that most of what occurs, from the effects of a single storm to the evolution of the human race, are like throwing darts at a board.  A particular event occurs from an infinitely rich set of possibly variation, but each possibility had an intrinsic probability of zero.  If that is the case, then the probability of you, me, or the human race ever having occurred is zero and even given infinite time should not be expected to recur.  Dragons flight 18:37, 2 September 2006 (UTC)


 * Dragons flight chose his words carefully, I want to point it out. If that is the case, then the probability of you, me, or the human race ever having occurred is zero and even given infinite time should not be expected to recur.  That's, of course, not to say that it couldn't recur, just it isn't expected.  Probabilities become very hard to understand intuitively when the number of trials is infinite.  So, for any event with probability zero, it could happen any finite number of times in an infinite number of trials.   With respect to your question if you assign the event that someone again has exactly the same thoughts as you a positive (non-zero) probability, then the probability it occurs again given an infinite number of trials, is 1.(*) However, if such an event has probability 0, given an infinite number of trials it might happen again, but it need not.   (*: This is so long as each individual trial is independent) --best, kevin [kzollman][talk] 20:51, 2 September 2006 (UTC)


 * It is probably theoretically possible for something to have, say 1/4 probability of ever happening given infinite time (if I have this right). Imagine that, starting now, for some x amount of time, an event has a 1/5 probability of happening within that time.  After that x amount of time, then for the next x amount of time, it has a 1/25 probability of happening.  Then it has a 1/125 chance, then 1/625, etc.  This goes on infinitely.  The sum of all those is not one (or infinity) but 1/4 (see geometric series - scroll down that page) - not one or zero.
 * (I know the numbers don't sum up that way - the 1/25 ends up being 1/25 of the remaining slice, not 1/25 of the total slice - but explaining all that would detract too much from the point.) —AySz88\ ^ - ^ 18:58, 2 September 2006 (UTC)

You have to remember that not all possible paths lead to all possible outcomes, when sonthings happens in the universe, it always cuts out the possibility of a an infinite number of alternative possibilities from ever happening. So basically, if the human race became extinct tomorrow, even if the universe existed for eternity, the possibility of someone exactly the same as you having the same thoughts as you is 0. Philc TECI 19:32, 2 September 2006 (UTC)


 * Schroedinger's cat?--Light current 20:19, 2 September 2006 (UTC)
 * I'm afraid I don't see how this is related. --best, kevin [kzollman][talk] 20:51, 2 September 2006 (UTC)
 * As a bit of nit-picking, there is no such thing as "infinitely improbable" in the standard real number system. Something either has probability 0 or a positive probability.  In order to have "infinitely improbable" one must introduce infinitesimals which results in a different theory of probability than is standardly used. --best, kevin [kzollman][talk] 20:51, 2 September 2006 (UTC)

See Infinite_monkey_theorem for an example of a finite, but highly improbable, event that would occur, given an infinite number of trials. StuRat 21:33, 2 September 2006 (UTC)


 * What do you think we're doing here?9-)--Light current 21:36, 2 September 2006 (UTC)


 * Except that we're not nearly as intelligent as the monkeys. :-) StuRat 21:42, 2 September 2006 (UTC)
 * Yeah, they got it made eating bananas, screwing round all day.... Hey hang on a minute- sounds familiar!--Light current 23:33, 2 September 2006 (UTC)

The formation of life on Earth may be similar. That is, it may be a highly improbably event, but, given all the planets and moons around all the stars, in all the galaxies in the universe, even highly improbable events become quite likely, somewhere. Then the not-too-bright say "but what was the chance it would have happened on the planet where we live ?". Well, the chance that life had evolved on any planet where life currently exists is actually quite good. StuRat 21:42, 2 September 2006 (UTC)


 * The flaw in the argument is that Kolmogorov et al are applying ideas from Pure Maths to Applied Maths (and then to Real Life). Things tending to particular limits as other things tend to infinity only means something in some very specific Pure Maths situations - to apply these processes to Applied Maths which is talking about real life is silly. Thats the flaw.
 * And since we're talking about real life I can postulate that the monkeys instead produce an infinite amount of garbage, or the atoms will come to resemble a donkey's thing, and you can't point to any real life cause which will necessitate that they do otherwise. Rentwa 22:31, 2 September 2006 (UTC)


 * What is zero multiplied by infinity? If you can do this, you have the answer.--Light current 22:35, 2 September 2006 (UTC)

Not defined by arithmetic, zero if calculated according to limits. Rentwa 22:40, 2 September 2006 (UTC)


 * It could be anything, calculated according to limits. For instance, lim(x->0) x(1/x)=1, x(2/x)=2, x2(1/x)=inf etc. If I may, though, I see some things that don't make sense to me. First, what does it mean to say that an event, like someone with a particular genetic code being born perhaps, has a particular "probability"? Or sentient life springing up, or whatever. The universe, above the quantum level, is as predetermined as clockwork. It's not a matter of manipulating random variables to get the answer, it's a matter of manipulating very very definite equations of physical motion. For instance, let's say we find the "probability" of a 2kg mass being pushed with 1N of force for 1s, but inexplicably gaining several thousand m/s of velocity. This would have a probability zero. Hitting a theoretical point with a theoretical dart has a probability "almost zero", meaning it could conceivably happen but almost certainly won't any time soon, but this just plain won't happen, ever. Am I right? So, it's not a question of whether a universe filled with random static could ever clear up for a moment into a universe with human life, it's a question of whether this universe, given its starting conditions and laws, will ever do so. Which it probably won't ever again, if the heat death theory is to be believed. The only thing that brings randomness into it is Schrodinger's cat, as someone earlier said, which is a demonstration of the link between the alleged pure randomness of the quantum world and normal events. Even given that, though, I doubt the question changes much.
 * BTW, something that crossed my mind, rereading the original question - If someone with your thoughts and memories were to show up later, given the strong link between thoughts and the reality that made them, that would suggest that the entire universe was on some sort of periodic cycle, wouldn't it? If the same things happened again, they would surely lead to the same results again, and therefore back to themselves again, ad infinitum. Only a universe where cause and effect weren't so closely linked, as in the imaginary random universe you're working with, could that not be the case. Black Carrot 23:15, 2 September 2006 (UTC)


 * Given multiplication of m by n is defined as adding n lots of m, 0 times infinity is the sum 0 + 0 +...+ 0 = 0 as the number of 0's tends to infinity, and it's trivial to prove lim = 0.


 * I've no idea what you're talking about :) . But you write very nicely. :) Very cool red sig btw. Rentwa 23:35, 2 September 2006 (UTC)


 * Are you familiar with the idea of a limit? Basically, it says that given a mathematical statement, we can get an idea how it behaves in a particular area by looking nearby. (Edit:Sorry, I just noticed you're the same guy as before.) The sum of an infinite amount of nothing certainly is nothing (stated I believe as $$\lim_{x \to \infty} \sum_{a=1}^x 0 =0$$ or as 0+0+...+0=0 or as $$\lim_{x \to \infty} 0x=0$$). It'll certainly never get bigger. However, take the function f(x)=x(1/x), which for x=1/5 for instance means (1/5 + 1/5 + 1/5 + 1/5 + 1/5) or (1/5)5. What does f(0)=0(1/0) mean? Well, at every point except x=0, this simplifies to f(x)=1, which suggests that f(0)=1 as well. But, on the other hand, g(x)=1/x gets arbitrarily large (as big as you want, then bigger) as x gets closer to 0, so g(0)=infinity, so f(0)=0(infinity). So, in two slightly different interpretations of 0 times infinity, it's reasonable to arrive at two very different answers, which is why arithmetic doesn't touch it. And thank you. Black Carrot 04:12, 3 September 2006 (UTC)


 * No, the axioms of arithmetic don't touch it because they only mention finite numbers (one or any of its successors). I can tell you're the same guy because of that cool red sig - and you write formulae very nicely too!


 * Your point about 0(1/0) I'm afraid isn't correct, 1/0 is not defined by arithmetic (just like arithmetic not defining operations with non-finite numbers) and therefore not part of functional analysis in general (isn't it wonderful, btw, that from an axiomatic point of view Analysis is hardly any bigger than Arithmetic?), although it is a neat un-rigorous way of showing zero times infinity is one. You could possibly make a more rigorous argument calling the point x = 0 a singularity.


 * The point to note is that you can use apparently sound logical ideas to get lots of different answers, which is why Pure Mathematicians devised analysis - so there was one realm of human thought at least that was bollocks free - which is why people are able to talk nonsense when they take sound ideas about limits and apply them to real events and end up with a monkey writing Hamlet. Rentwa 11:54, 3 September 2006 (UTC)

I would still like to know if the universe will exist for an infinite length of time or not. Perhaps it goes through an infinite number of big bangs. Or perhaps there are an infinite number of universes, where I am having exactly this same thought. Or perhaps nobody will ever know.


 * According to Thermodynamics things get hotter and more disordered unless you keep supplying them with enegy, and since there's nothing outside the universe to put energy into it, it will end in a 'heat death' (although it will only warm up by a tiny fraction of a degree due to its size).


 * If you're wondering whether or not this is likely, and how reliable thermodynamics is, one of the famous physicists working at the turn of the century in quantum mechanics (I forget who - does anyone know?) said in investigating the apparently bizarre world of the sub-atomic, that he was willing to reject every Law of Physics except Thermodynamics. So I'm voting for heat death.


 * There is modern work that contradicts it, but I'm not familiar with it and I'd guess it was a little dubious.


 * Re extra dimensions etc, I think it's best to remember what the logical positivists were trying to say: if there's no good evidence for it or it doesn't help to explain things that were previously inexplicable (rather than pander to wishful thinking) then there's no reason to say it. Rentwa 15:11, 3 September 2006 (UTC)


 * Read Ultimate fate of the universe. --Lambiam Talk 16:22, 3 September 2006 (UTC)


 * Lambiam - do you know which Physicist it was who said he was willing to discard everything except the second law? Rentwa 19:27, 3 September 2006 (UTC)


 * I'll take that as a 'no', then, shall I? :) Rentwa 12:58, 4 September 2006 (UTC)


 * Rentwa - Fair enough. There's a much better reason for it not to be taught in arithmetic - the fact that they're completely different. For the rest - I wrote an intentionally lazy and hand-waving description because I figured it'd get the point across. I'm not quite sure, though, whether you're agreeing with me or disagreeing. I'm also curious whether I'm farther in math than you are, or vice versa. I'm not familiar with the phrase "functional analysis". To put it in the most rigorous, or at least most clear, way I've learned:
 * 1a)$$f(x) = 0x \qquad$$
 * 1b)$$\lim_{x \to \infty} f(x) = 0$$
 * 1c)$$\lim_{x \to \infty} 0x$$ is of the form 0 times infinity, so in one situation 0 times infinity = 0
 * 2a)$$g(x) = x(1/x) \qquad$$
 * 2b)$$g(x) = 1, x \ne 0 $$
 * 2c)$$\lim_{x \to 0} g(x) = 1$$
 * 3a)$$g(x) = h(x)i(x), h(x) = x, i(x) = 1/x \qquad$$
 * 3b)$$h(0) = 0, \lim_{x \to 0} i(x) \to +\infty$$
 * 3c)$$\lim_{x \to 0} g(x) = \lim_{x \to 0} h(x)i(x) = 0 (\lim_{i(x) \to \infty} i(x))$$ is of the form 0 times infinity as well, but evaluates to 1. The same steps could show that lim(x->0)x2(1/x)4=inf. Or just looking at their graphs, which is basically what this formalizes, could show the same thing - a flat line at one place versus a flat line at another place versus a vertical asymptote. So, the statement "0 times infinity" is ambiguous. It's not that any of the answers is wrong, it's that the right answer depends on the actual relationship between the two objects/values/measurements described. Black Carrot 21:32, 3 September 2006 (UTC)


 * I studied Maths up to postgraduate level, although I don't work in the field now (and I never taught in any very prestigious institutions when I did).


 * Argument 2) is fine I think except that there are very rigorous rules in analysis for letting you say that the value is what it looks like at the point you can't work out (obviously the graph is flat across its domain with g(x) = 1), and without my text books to hand I can't remember what they are (I'm on holiday and still spending 10+ hours a day ranting on wikipedia - how sad is that?)


 * I'm agreeing with you that you've got a good way of showing that 0 x infinity = 1, I'm just not sure it's rigorous without checking the rules, whereas I don't need to check the rules to know that the sum of 0s = 0 or to remember the axioms of arithmetic from my undergraduate Logic course.


 * 'Functional Analysis' = 'Analysis' = rigorous treatment of functions, it's the broad topic that calculus falls into at university.


 * What you're saying at the end is what led me to analysis and the philosophy of logical positivism - that you have to think very carefully about what you mean, the symbols you use and the rules governing those symbols or you end up talking rubbish. Rentwa 22:55, 3 September 2006 (UTC)

THeres no such thing as zero probability in nature anyway. Only in mathematics. So the argument is rather sterile.--Light current 23:00, 3 September 2006 (UTC)


 * Rentwa - I'm in undergraduate Calc II, plus some study beyond the classroom. So, you'd get the benefit of any doubt. You've got a good point, that it takes a bit more to actually prove that the limit works that way, but I'm almost certain that the necessary argument exists, somewhere. I think that because we've evaluated those limits and ones like them in class many times, and the teachers seem pretty sure that that's how it winds up. What are some good textbooks for that kind of thing? Black Carrot 03:02, 4 September 2006 (UTC)
 * Light current - A fair point. Black Carrot 03:02, 4 September 2006 (UTC)


 * I always give myself the benefit of the doubt :) . And the more I think about it, the more 'Prove f(x) = x (1/x) is continuous' sounds like a question, so you're probably right, it's just I want to see 'blah blah (such and such theorem), blah blah (since x is a member of R) blah blah etc before I give you a tick :) . To take things to a more philosophical level (and draw attention away from the fact that I can't remember the rules for continuity), both the 'infinite monkeys' and 'Schrodinger's Cat' strike me as proofs by contradiction eg:


 * assume we can apply limits to real life,


 * do various other steps, all 100% logical,


 * conclude monkey can write Hamlet,


 * in a lucid moment realise that a monkey couldn't write Hamlet, thus proving original assumption is wrong.


 * Likewise:


 * assume quantum super position,


 * use various other steps, all 100% logical,


 * conclude cat can be simultaneously dead and alive,


 * in lucid moment realise cats are one thing or the other, thus proving quantum super position is wrong. Rentwa 09:21, 4 September 2006 (UTC)

Iron
What do you get when you mix oxygen with iron? 64.12.116.74 20:06, 2 September 2006 (UTC)


 * I'd like to help you out, but my chemistry is rusty. ---Sluzzelin 20:08, 2 September 2006 (UTC)


 * Ha Ha. I think you could get a lot of things (one of upto sixteen different oxides) depending on how you did it. But see iron, Iron oxide, ferric oxide to start.--Light current 20:11, 2 September 2006 (UTC)


 * Hehe, sluzzelin, it depends though, on temperature and for how long, but if given enough time and or heat, you will get the iron oxides light current mentioned. Philc  TECI 20:53, 2 September 2006 (UTC)

I prefer to call it "ironic oxide", since you work hard to replace your rusty old car with a shiny new car, then it turns to rust as you work hard for the next shiny new car, etc. :-) StuRat 21:25, 2 September 2006 (UTC)

Quite simple
Dirk vs. StuRat? ≈Eh-Steve 21:08, 2 September 2006 (UTC)


 * Hmmmm... --Russoc4 02:02, 3 September 2006 (UTC)

But to make it a fair fight, you must use both our full screen names, so DirkvdM vs StuRat. StuRat 02:18, 3 September 2006 (UTC)


 * Im far too common to enter such a contest!--Light current 02:44, 3 September 2006 (UTC)


 * Are we being pitted against each other? As if we need the incentive of others for that. And which one is supposed to be "quite simple"? Anyway, there appear to be many StuRats. For example, is this you? If we limit this to Wikipdia we get StuRat 538 vs DirkvdM 886. But to distinguish between us without limiting the search to Wikipedia we could use our real names. here's mine: Dirk van der Made, with a score of 1270. DirkvdM 06:26, 3 September 2006 (UTC)


 * When I picked your links I get me ahead with 362 vs. 348 for you. StuRat 07:45, 3 September 2006 (UTC)


 * What, you get significantly different results? Shouldn't this be the same the world over? DirkvdM 08:08, 3 September 2006 (UTC)


 * That's what I was expecting. How many hits does everybody else get on Dirk's links ? StuRat 11:31, 3 September 2006 (UTC)


 * I'll ask about this at the IT ref desk. DirkvdM 13:53, 3 September 2006 (UTC)


 * I should note that there's this other Dirk van der Made from the 13th centrury. Excluding him gives only 865 results. Most of these are a result of the popularity of my photographs on the Internet. Looking through that list is quite interresting - haven't done that for some time. I now see that someone thinks I have tremendous potential. I just don't know for what (my life's story :) ). DirkvdM 07:22, 3 September 2006 (UTC)


 * Saying you have "potential" is shorthand for "wasted potential". It's something like saying a woman has "a good personality", LOL. StuRat 08:02, 3 September 2006 (UTC)


 * I have some 2000 more Wikipedia edits:


 * StuRat's edit count


 * DirkvdM's edit count


 * StuRat 07:36, 3 September 2006 (UTC)


 * If you have (slightly) more Wikipedia edits than me and I get more Wikipedia hits, does this mean that I am talked about more? In other words, am more interresting than you? DirkvdM 08:08, 3 September 2006 (UTC)


 * Yes, apparently you are all talk, while I am a man of action. Note that thousands of additional edits isn't a "slight" amount, and I don't agree that you have more Wikipedia hits from Google (that's not what I get when I pick your links). StuRat 11:36, 3 September 2006 (UTC)


 * But you have to view that in relation to the total count. You have 9394 edits and I have 7628 edits. That's a difference of 1766, and 'thousands' is in my vocabulary at least more than 2000. Now who isn't a math graduate? Ok, so you have 23% more edits and are in that sense 23% more action (but is ceterus paribus? How many political parties have you started?). But based on my Google results I am 65% more talk, and thus 65% more interresting. DirkvdM 13:53, 3 September 2006 (UTC)


 * I said Wikipedia edits (as opposed to total edits), which favors me by 6327 to 3528. That's a diff of 2799, or 79% more for me.  I can both do math AND read, whereas you, apparently, can only talk. :-) StuRat 03:43, 4 September 2006 (UTC)


 * What do you know, I may be a mute. You mean 'write'. Anyway, you just made that up. If you meant 2799, you wouldn't have said 'some 2000' but something like 'well over 2000' or 'almost 3000'. Also, I'm more of a help because I've got infinitely many more edits there than you. Ok, that was silly. :) DirkvdM 07:25, 4 September 2006 (UTC)


 * We are making up the rules of this contest as we go (and as suits us). Eh-Steve, could you emphazi your intentions here a bit more? DirkvdM 08:08, 3 September 2006 (UTC)


 * 5 wikidollars on StuRat. And, just in case, put me in for 4 wikidollars on DirkvdM, too. freshofftheufo  ΓΛĿЌ  10:04, 3 September 2006 (UTC)


 * Being a bit indecisive? You place 20% more on StuRat. Ist that based on the 23% more action? But then what about my 65% more interrestingness? (As exemplified by my linguistic inventiveness.) DirkvdM 14:02, 3 September 2006 (UTC)


 * 5 is 25% more than 4, since the basis is 4. However, 4 is 20% less than 5, since the basis is 5.  StuRat 04:34, 4 September 2006 (UTC)


 * Hmmm, I wonder how that sneaked in. Maybe I did use the wrong base. Anyway, 25 is closer to 23, so that fits even better. Btw, this reminds me of the Philippines, where (like in the US) they very oddly substract taxes from the prices and then add them back again before the sale. Thus, you often get very weird prices, but with tax they are miraculously round again. In one hamburger joint they hadn't done this right, though, calculating the substracted tax percentage based on the full price, so adding it back (based on the 'untaxed price') gave too low a result. I decided not to point this out because I had a hard enough time getting a hamburger (in a hamburger joint!). "A hamburger please" "A hawaiian burger?" "No just a plain hamburger" "A cheeseburger?" "No, a hamburger" "A what-have-you burger" "No, I just just want a plain fucking hamburger" Startled looks, but I thought I had gotten through to her. But then "What about your drink sir?" AAARghhhh!! DirkvdM 07:25, 4 September 2006 (UTC)


 * We saw a Dutch guy on holiday. He had 'Fuck off' tattooed on his leg. We stared at him for a long time. Eventually we went up to him. 'You have 'Fuck off' on your leg' we said. 'Yes' he said. 'Why have you got 'Fuck off' tattooed on your leg?' we said. 'It's a very useful phrase in Holland' he said. We backed away slowly... Rentwa 19:56, 4 September 2006 (UTC)


 * In Los Angeles, when you go to Jack in the Box for a hamburger, the Hispanic server says "Welcome to Yak in the Box" ... it must be a mighty big box ! :-) StuRat 08:30, 4 September 2006 (UTC)

This might be a challenge for me to suitly emphazi, because I just wanted to see what would happen between you two (Y'all are always quarrelling about lefty vs. US politics, as far as I can tell, more than any other 2).

So... How about a deathmatch (like giant seagull vs. Human)? ≈Eh-Steve 15:45, 3 September 2006 (UTC)


 * As long as it's virtual death (what else could it be over the Internet?). Btw, it's mostly over politics that we're head to head. When it comes to science and especially humour we're often of the same mind. However, in all areas we try ot outwit each other, and to some that might come across as something more serious.
 * So a deathmatch it is. What are our weapons? DirkvdM 17:54, 3 September 2006 (UTC)


 * You don't need any weapons, you're already working to arm the terrorists with nuclear weapons, so they will get me for you. StuRat 04:24, 4 September 2006 (UTC)


 * The Netherlands supply the US with arms? DirkvdM 07:25, 4 September 2006 (UTC)


 * I think it should be te person withe the fewest Google hits who wins. This shows the originality of the name. In this case, I lose by a massive amount! 8-)--Light current 18:05, 3 September 2006 (UTC)


 * HEY you two! My Dad's bigger than either of your Dads. So there!--Light current 03:49, 4 September 2006 (UTC)


 * Please dont turn this desk into a complete joke eh?--Light current 03:57, 4 September 2006 (UTC)

Damn you both for letting all this fun go on without telling me! Sure, I can't compete with either Dirk or Stu when it comes to edits or google hits, but as the RefDesk's resident right-wing, Canadian, pro-US, anti-UN, Republican, shit-disturbing Zionist Jew, I'd think I'd at least get honourable mention! Loomis 02:49, 5 September 2006 (UTC)


 * Maybe I'll sick you on Dirk, to counter all those nuclear weapons he wants to give to terrorists to get me. :-) StuRat 07:42, 5 September 2006 (UTC)

What? Nobody's mentioned Magical MD5 Battle? StuRat won against DirkvdM after 5 rounds. --Kjoonlee 17:43, 5 September 2006 (UTC)
 * StuRat: ヽ( ´￢`)ノ, DirkvdM: (ﾉд-｡). Can I get my 5 Wikidollars now? freshofftheufo  ΓΛĿЌ  05:54, 6 September 2006 (UTC)

Northern Cardinal question
There was a fledgling cardinal in our yard about 2 weeks ago--it didn't look like a cardinal, but it was being fed by cardinal parents, and it couldn't fly. We were worried about it because it kept hopping into dangerous areas, like the sidewalk, etc. Now there is a red male cardinal hanging around, but no parents. Is it possible this is the fledgling? How long does it take a fledgling to get its red feathers?

Thanks!


 * This is a rather entertaining story until you realise it's about birds. :) DirkvdM 06:28, 3 September 2006 (UTC)
 * I remember when the racehorse Cardinal was retired. The headline said "Cardinal out to stud". JackofOz 12:08, 3 September 2006 (UTC)
 * At least it was not Cardinal Sin. --Lambiam Talk 16:42, 3 September 2006 (UTC)

sun slowing down
i know the moon is slowly nicking the earths angualr momentum, so does in theory the planets takie angular momentum from the sun? if so, excluding events like sun turning into a red gaint (or the IAU decides to change definition of a planet again)how long would it take with the current planets to stop the sun spinning?--Colsmeghead 23:01, 2 September 2006 (UTC)
 * Not sure, but since the Sun is almost 1.98×1030 kilograms, and even Jupiter being a mere 1.90x1027 kilograms, the combined mass of all the planets and other objects in the solar system, probably aren't enough to actually cut into the Sun's angular momentum, at least not in a way that will have a significant effect within the life time of the solar system--71.247.243.173 00:06, 3 September 2006 (UTC)
 * That's only 1/1000th of the sun's mass... sure it's small, but is it really negligible? Aaadddaaammm 01:14, 3 September 2006 (UTC)


 * It's the tides that cause Earth to lose angular momentum. Using this formula, I calculated the tidal forces that the planets exert on the Sun:


 * Mercury: 3.140135 x 1020 N


 * Venus: 7.104643 x 1020 N


 * Earth: 3.300665 x 1020 N


 * Mars: 1.001771 x 1019 N


 * Jupiter: 7.446589 x 1020 N


 * Saturn: 3.619013 x 1019 N


 * Uranus: 6.786093 x 1017 N


 * Neptune: 2.072556 x 1017 N


 * So if Jupiter and Venus are at a 90-degree angle with respect to the Sun, their tides will cancel each other. If there's a syzygy involving Mercury, Earth, and the Sun, and if Venus (or Jupiter) is at a right angle to Mercury, then Mercury and Earth's combined tide will almost cancel that of Venus/Jupiter.  Also, if Mercury is at a right angle to Earth, their tides will cancel.
 * As you can see, the situation is very complex when there's 8 planets involved. With the planets cancelling and overpowering each other's tides, we probably need to run a computer simulation to find out what happens.  But even if the Sun is losing angular momentum, it won't stop rotating.  I'll use Earth as an example to explain why:  the Moon's gravity changes the shape of the Earth, slowing Earth's rotation and in the meantime lengthening the Moon's orbital period.  When the length of an Earth day is equal to the Moon's orbital period, Earth's shape will not change anymore, because the Moon will be stationary relative to our planet.  When this happens, the length of a day will be fixed forever.  --Bowlhover 05:38, 3 September 2006 (UTC)


 * But, as you say, the solar system is more complex, with all its planets and planetoids and what have you. I wonder if all planets, through their mutual attraction would in the end become stationary relative to each other. But since a given orbit period corresponds to a given orbital radius, all planets would have to merge for this to happen. Is that a state the solar system is moving towards? DirkvdM 06:37, 3 September 2006 (UTC)


 * No, the planets don't have any reason to merge. The force that the planets exert on each other is very small, certainly not enough to change the planets' orbits to any extreme degree.  --Bowlhover 06:54, 3 September 2006 (UTC)


 * I think, in theory, they would eventually merge. But, since that would take far longer than the time before the Sun goes nova, it's not really important. StuRat 03:00, 9 September 2006 (UTC)