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{{Wikipedia:Reference_desk/Archives/Science/2007 June 20}}
{{Wikipedia:Reference_desk/Archives/Science/2007 June 21}}
= June 22 =
== Amino acid analysis: Asn and Gln always missing ==
In every nutritional amino acid analysis I've seen so far, [[asparagine]] and [[glutamine]] are missing. They are not nutritionally important, but the same applies to other amino acids which aren't missing. Why are '''Asn''' and '''Gln''' missing? [[User:Icek|Icek]] 01:06, 22 June 2007 (UTC)
= August 12 =
It has probably something to do with the fact that they are the only (biochemically relevant) amide-containing amino acids. Maybe the chemical process used to dissolution of the peptide bonds for analysis destroys these amides and converts them to [[aspartate]] and [[glutamate]]? [[User:Icek|Icek]] 01:30, 22 June 2007 (UTC)
== What is this species of bean? ==
:Hit the nail on the head there, if only everyone answered their own questions! :) [[User:Aaadddaaammm|Aaadddaaammm]] 01:34, 22 June 2007 (UTC)
[[File:Speckled butterbeans 2025.jpg|right|thumb|100px|Speckled butterbeans]]
:My fav nutrition site: [http://www.nutritiondata.com/facts-C00001-01c20Tl.html] lists [[aspartic acid]] and [[glutamic acid]]. [[User:StuRat|StuRat]] 06:57, 22 June 2007 (UTC)
These are called "speckled butterbeans" and they are discussed in [[lima bean]]. However, the article says that lima beans grow in the eastern US in "Delaware and the mid-Atlantic". These are from farther south. Their taste is quite different from what are known as lima beans. What species are they? [[User:Bubba73|Bubba73]] <sup>[[User talk:Bubba73|You talkin' to me?]]</sup> 19:40, 12 August 2025 (UTC)
:Hey Bubba: lima beans originate from meso-America and the Andes (hence the name), but were apparently domesticated independently at least twice, and there are numerous different cultivars today. However, they are all constitute a single species (''Phaseolus lunatus''), and I suspect most varieties would grow quite well throughout most of the Southern U.S., considering their original geographic/ecological distribution. Indeed, lima bean article contains a picture of speckled butterbeans which indicates the specimens in question were grown in the state of Georgia. So the article's description of their horticulture in the U.S. might just not be exhaustive and precise enough. But yes, despite the difference in morphology/appearance and taste from those that may be more familiar to you, these are also lima beans. ''[[User:Snow Rise|<b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b>]][[User talk:Snow Rise|<sup><b style="color:#d4143a"> let's rap</b></sup>]]'' 23:22, 12 August 2025 (UTC)
::Yes, but you don't know how much of the aspartic acid was originally asparagine and how much of the glutamic acid was originally glutamine. [[User:Icek|Icek]] 13:43, 23 June 2007 (UTC)
::Oh look: they somewhat match the color scheme of my signature. Very aesthetically pleasing coincidence. :) ''[[User:Snow Rise|<b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b>]][[User talk:Snow Rise|<sup><b style="color:#d4143a"> let's rap</b></sup>]]'' 23:24, 12 August 2025 (UTC)
::: Thanks, they are so different in looks and taste (and growing region) that I didn't think they were the same species. The photo of speckled butterbeans in the [[lima bean]] article is mine. I put it there years ago because I found "speckled butterbeans" mentioned in that article. [[User:Bubba73|Bubba73]] <sup>[[User talk:Bubba73|You talkin' to me?]]</sup> 00:41, 13 August 2025 (UTC)
== Bugs ==
::::The beans shown above are variegated, but I wouldn't call them "speckled", unlike those in the photo in [[Lima bean]]. Several of the beans above, in particular the reddish ones, have noticeable fans of streaks, not seen in most bean varieties. I see a similar pattern in [https://rohrerseeds.com/cdn/shop/files/ChristmasPoleLimaBean_2032x1350.jpg?v=1710433634 these lima beans]. Different varieties of ''Phaseolus vulgaris'' do taste differently, so I expect this can also be the case for different varieties of ''Phaseolus lunatus''. ​‑‑[[User talk:Lambiam#top|Lambiam]] 10:15, 13 August 2025 (UTC)
:Keep in mind most all bean varieties are developed from just a handful species, and that varietal differences can be huge.
I'm wondering what type of bug this is. Can anyone help me identify it?
:As a point of reference, broccoli, cabbage, cauliflower, and kale are all ''[[Brassica oleracea]]''. [[User:SemanticMantis|SemanticMantis]] ([[User talk:SemanticMantis|talk]]) 16:54, 13 August 2025 (UTC)
::Kale too? I didn't realize. Hey Semanto-Manto: good to see you--I wasn't sure we would again! ''[[User:Snow Rise|<b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b>]][[User talk:Snow Rise|<sup><b style="color:#d4143a"> let's rap</b></sup>]]'' 21:37, 13 August 2025 (UTC)
:::Yep, and collards and kohlrabi too! ''[[Brassica rapa]]'' also has many distinct culinary varieties, from turnips to bok choi to rapeseed. I did take a break for a while but I have my professor hat back on and I plan to hang out around here a bit more. Good to see you too :) [[User:SemanticMantis|SemanticMantis]] ([[User talk:SemanticMantis|talk]]) 00:03, 14 August 2025 (UTC)
::::I've heard grumblings that some of the cultivars of ''Brassica oleracea'' and ''Brassica rapa'' might have some genetic input from other species. <span style="font-family: Cambria;"> [[User:Abductive|<span style="color: teal;">'''Abductive'''</span>]] ([[User talk:Abductive|reasoning]])</span> 18:46, 14 August 2025 (UTC)
= August 13 =
http://tinypic.com/view.php?pic=6fz9ufa
== How to start making cellular automata ==
is the picture of it. My girlfriend took a picture of it since she is wondering as well. It is stuck between her window and screen. It can fly obviously. My girlfriend has woods in her backyard and it has lots of bugs, trust me. Any help would be appreciated. Thank you.
What's the way to get into cellular automata? What's a good book to read with interesting "case studies?" I'm interested in things like varied fields with rules diversified within that create conditions for filtering and longevity of items. Neural automata within classical fields. User manipulation to make attractor conditions or simple destruction of items. Fun stuff like that. A glossary of terms would be a help too. Thank you.
[[User:Gongula Spring|Gongula Spring]] ([[User talk:Gongula Spring|talk]]) 19:00, 13 August 2025 (UTC)
:Are you talking about [[Cellular automaton]]? ←[[User:Baseball Bugs|Baseball Bugs]] <sup>''[[User talk:Baseball Bugs|What's up, Doc?]]''</sup> [[Special:Contributions/Baseball_Bugs|carrots]]→ 20:58, 13 August 2025 (UTC)
:We can give you better direction if you tell us a little about where you're starting from. Do you know any programming already, and if so, what languages?
:On balance, Netlogo is a good system for cellular automata and other similar types of simulation and modeling. See eg [here](https://ccl.northwestern.edu/netlogo/models/CA1DElementary) [[User:SemanticMantis|SemanticMantis]] ([[User talk:SemanticMantis|talk]]) 00:13, 14 August 2025 (UTC)
::I can't say I haven't tried programming before, but I can confidently deny any proficiency. [[User:Gongula Spring|Gongula Spring]] ([[User talk:Gongula Spring|talk]]) 00:47, 14 August 2025 (UTC)
:::Rather a deep dive, Wolfram's ''[[A New Kind of Science]]'' can be read for free as an [https://www.wolframscience.com/nks/ e-book]. Linear (one-dimensional) cellular automata, which include the [[Turing machine]]s, are introduced on page 24, while two-dimensional cellular automata make their first appearance on page 170. ​‑‑[[User talk:Lambiam#top|Lambiam]] 02:07, 14 August 2025 (UTC)
::::Our article on [[Conway's Game of Life]] gives a good overview of one of the first such programs. I remember coding that up in machine code on a [[ZX81]], which was how I first became interested in computing. [[User:Michael D. Turnbull|Mike Turnbull]] ([[User talk:Michael D. Turnbull|talk]]) 19:11, 15 August 2025 (UTC)
::::Thanks! And wow, Wolfram writes interesting, doesn't he? I can stand the arrogance, but not the repetition. I found this recent paper on longevity: https://arxiv.org/abs/2507.12306
::::[[User:Gongula Spring|Gongula Spring]] ([[User talk:Gongula Spring|talk]]) 19:20, 15 August 2025 (UTC)
= August 14 =
== Why wasn't snow always visible on analogue TV? ==
:It looks a bit like an ant or wasp to me, [[User:Graeme Bartlett|GB]] 03:28, 22 June 2007 (UTC)
::Maybe a [[black wasp]], [http://entweb.clemson.edu/museum/webonly/local/lmisc/lmisc40.htm like this].. [[User:Vespine|Vespine]] 03:34, 22 June 2007 (UTC)
[[File:FREE real VHS static.webm|right|250px]] If you tuned an analogue TV to any channel which didn't have a station transmitting on it, you would see [[Noise (video)|snow]] and hear white noise. This was because you were picking up the omnipresent background noise, from such sources as dying stars.
:It's definitely Order [[Hymenoptera]], most likely a wasp of some sort, you can tell by the thorax. There aren't enough details in the image to be sure, but you could probably look up what wasps are common in your area. -- [[User:Jsbillings|<span style="color:green">JSBillings</span>]] 12:23, 22 June 2007 (UTC)
All very well, but why weren't the pattern and the noise imposed over every broadcast channel? If it's just that the signal from the transmitter was louder than the background noise, why wasn't the background noise grey? [[User:Marnanel|Marnanel]] ([[User talk:Marnanel|talk]]) 13:38, 14 August 2025 (UTC)
== thermodynamics: ==
:[[Automatic gain control]] turned the gain to maximum in the absence of a signal [[User:Catslash|catslash]] ([[User talk:Catslash|talk]]) 13:48, 14 August 2025 (UTC)
Woul you pliz explain to me the following:
:The signal to noise ratio is massive in a properly tuned TV or radio. That background noise is multiple orders of magnitude lower in amplitude than the broadcast signal being beamed at high power from nearby.
:Edit: Btw, TV snow is the exact same phenomenon as static on a radio that's not tuned to a station or is moving out of range. That gain that that [[User:catslash|catslash]] mentions is a technique used to ensure the radio doesn't change in volume as you receive more or less of the signal due to distance. If you've ever heard a radio station gradually growing staticky as you drive out of range, that's what's going on -- it's amplifying the signal, and the noise with it, until all you can hear is the noise. We just don't tend to gradually move out of range of TV stations. -- [[User:Avocado|Avocado]] ([[User talk:Avocado|talk]]) 13:51, 14 August 2025 (UTC)
1.)A professor parked his car for eight hours in a shed, checked the pressure and found it to be normal for his car/ He the drove for thirty(30)minutes to a supermarket and then discovered that the pressure had slightly increased. In his wisdom, he decided to let some air out to reduce its original level.Comment on this action.
::Noise radiation from star sources and the CMB (Cosmic Background Noise) are detectable by sensitive radioastronomy antennas with ultra-low noise amplifiers. Domestic analog TVs are quite incapable of displaying such noise. Describing the off-program "snow" display as interstellar in origin is a common "lie to children". What one is actually seeing is thermal noise generated in the TVs own input circuit that greatly exceeds any supposed signal from space. <!-- Template:Unsigned IP --><small class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/2A02:FE1:4088:5E00:454:9CE8:B297:115F|2A02:FE1:4088:5E00:454:9CE8:B297:115F]] ([[User talk:2A02:FE1:4088:5E00:454:9CE8:B297:115F#top|talk]]) 08:40, 16 August 2025 (UTC)</small> <!--Autosigned by SineBot-->
:::Over here tv stations kept transmitters off during the day and if TV was turned on it was Cosmic Noise audible with dots very fine small dancing dots and TV technicians used to asses the quality of TV reception to be after few hours , it was always correct .Tv sets were CRT, B & W . [[User:Dr chifti|Dr chifti]] ([[User talk:Dr chifti|talk]]) 05:25, 26 August 2025 (UTC)
= August 15 =
2.)A container has 2500moles of air. Find the change in internal energy if its cooled from 30 degees celcius to 20 degrees celcius at constant pressure of 1atm. Treat the gas as an ideal gas.
:Definately looks like homework to me. -- [[User:Jsbillings|<span style="color:green">JSBillings</span>]] 13:27, 22 June 2007 (UTC)
::Maybe even [[Wikipedia:Reference_desk/Science#thermodynamics|yesterday's homework]]? [[User:213.48.15.234|213.48.15.234]] 13:33, 22 June 2007 (UTC)
:::How strange? :). In any case, why don't you ask your teacher for help?--[[User:GTPoompt|GTPoompt]][[User talk:GTPoompt|<small>(talk)</small>]] 14:35, 22 June 2007 (UTC)
::::Read [[ideal gas law]], and good luck with your homework! [[User:TomTheHand|TomTheHand]] 15:19, 22 June 2007 (UTC)
== pregnancies ==
:I even [[Wikipedia:Reference_desk/Science#thermodynamics|answered yesterday's homework]]! To the original poster: Pliz put a little effort in, we're assuming good faith. [[User:Nimur|Nimur]] 18:24, 22 June 2007 (UTC)
{{collapse top|title=Trolling. [[User:-insert valid name here-|-insert valid name here-]] ([[User talk:-insert valid name here-|talk]]) 21:07, 15 August 2025 (UTC)}}
== Definition of temperature units ==
which appropriate discussion website can i talk about pregnancies because i am a student ashley researching pregnancies?([[Special:Contributions/117.202.165.2|117.202.165.2]] ([[User talk:117.202.165.2|talk]]) 18:45, 15 August 2025 (UTC)
:Probably best just to use a search engine to find suitable sites. For example [https://www.reddit.com/r/pregnant/ reddit] or [https://www.mumsnet.com/talk/pregnancy Mumsnet]. [[User:Michael D. Turnbull|Mike Turnbull]] ([[User talk:Michael D. Turnbull|talk]]) 19:02, 15 August 2025 (UTC)
The Wikipedia articles on [[kelvin]] and [[degree Celsius]] both define the respective units in terms of two fixed points: absolute zero and the triple point of specially formulated water. However, neither of them makes any reference to the thermometer (or equivalently, the procedure for extrapolating the scale). The mid-point between the two fixed points as measured by one type of thermometer is not necessarily the mid-point as measured by another type of thermometer.
:Last time, you said your name was Lisa.[https://en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Science&diff=prev&oldid=1305786495] You need to get your trolling stories straight. ←[[User:Baseball Bugs|Baseball Bugs]] <sup>''[[User talk:Baseball Bugs|What's up, Doc?]]''</sup> [[Special:Contributions/Baseball_Bugs|carrots]]→ 19:12, 15 August 2025 (UTC)
My question is: Is there an implied thermometer or physical phenomenon that is used to extrapolate the Kelvin and Celsius scales (beyond the two fixed points)? If so, what is the thermometer/phenomenon?
::i do not know any lisa. did you check my ip address because there are tons of students researching pregnancies obviously?([[Special:Contributions/117.202.165.2|117.202.165.2]] ([[User talk:117.202.165.2|talk]]) 19:27, 15 August 2025 (UTC)).
:::You don't know any Ashley either. ←[[User:Baseball Bugs|Baseball Bugs]] <sup>''[[User talk:Baseball Bugs|What's up, Doc?]]''</sup> [[Special:Contributions/Baseball_Bugs|carrots]]→ 19:45, 15 August 2025 (UTC)
::::angry 😡 i do not like your accusations i am ashley leave me alone.
::::by the way, i am visiting india.
::::where can i discuss indian films online?([[Special:Contributions/117.202.165.2|117.202.165.2]] ([[User talk:117.202.165.2|talk]]) 20:07, 15 August 2025 (UTC)).
[[File:DoNotFeedTroll.svg]] <!-- Template:Unsigned --><small class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Baseball Bugs|Baseball Bugs]] ([[User talk:Baseball Bugs#top|talk]] • [[Special:Contributions/Baseball Bugs|contribs]]) 20:28, 15 August 2025 (UTC)</small> <!--Autosigned by SineBot-->
(I seem to recall from many years ago that my physics teacher said that constant-volume gas thermometer is used for the purpose, but I'm not sure.)
So...normally I would respect the close box and the call of a regular colleague make a troll call, but in this case I think it is worth asking: are we sure this is not someone very young and/or from a culture where discussion of reliable facts about reproductive health is taboo or restricted enough that they felt awkward asking these questions without a cover story? what exactly was asked, last time? ''[[User:Snow Rise|<b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b>]][[User talk:Snow Rise|<sup><b style="color:#d4143a"> let's rap</b></sup>]]'' 09:27, 16 August 2025 (UTC)
: It seems to me that the problem here can be sorted out by knowing what [[Temperature|temperature]] is. Once we know that, we can define <math>T_0</math> to be the temperature of said triple point. The kelvin is then defined as <math>1\,\mathrm{K}=T_0/273.16</math>. —[[User:Bromskloss|Bromskloss]] 16:41, 22 June 2007 (UTC)
:The user is a long-standing troll who always gets around to griping about some TV show and some plot line about pregnancy. His geolocate could indicate anywhere in the world, as he is presumably using a VPN tool to accomplish that bit of fakery. ←[[User:Baseball Bugs|Baseball Bugs]] <sup>''[[User talk:Baseball Bugs|What's up, Doc?]]''</sup> [[Special:Contributions/Baseball_Bugs|carrots]]→ 10:28, 16 August 2025 (UTC)
::Ok, thanks for the extra context, Bugs: feel free to manually erase my inquiry and your own post, if you think that is the best approach to [[WP:DENY]] in this instance. ''[[User:Snow Rise|<b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b>]][[User talk:Snow Rise|<sup><b style="color:#d4143a"> let's rap</b></sup>]]'' 11:10, 16 August 2025 (UTC)
{{collapse bottom}}
= August 17 =
:As my professor once said, temperature is that thing that [[thermometer]]s measure. An ideal thermometer is linear so that the change in temperature is proportional to the input in thermal energy. An [[ideal gas]] themometer is a reasonable approximation of this at modest temperatures and far from phase transitions. In practice though there are a whole host of different thermometers and techniques used to extrapolate over different ranges of temperature. I've seen a list before, but don't have it handy. Inventing a truly precise absolute themometer that works over a large dynamic range is an engineering challenge that has yet to be solved. [[User:Dragons flight|Dragons flight]] 16:52, 22 June 2007 (UTC)
== flocking and threshold ==
The answer is that the SI standard defines the kelvin specifically as being the unit of [[thermodynamic temperature]], which as you can see at that page, means the average kinetic energy of the translational motions of the particles making up the substance. This is the "physical phenomenon" that thermometers attempt to measure. --Anonymous, June 23, 2007, 08:58 (UTC).
[[Boids]] provokes a question:
== Insulation ==
Each boid adjusts its position and velocity to those of (I guess) its N nearest neighbors; and/or those within a distance R. Does varying N or R make the behavior resemble that of different real bird species? [[User:Tamfang|—Tamfang]] ([[User talk:Tamfang|talk]]) 03:04, 17 August 2025 (UTC)
I have always been wondering....does the insulation coating of a conducting wire have anything to do with its current conducting capacity?I mean does the plastic insulation coating on the top affect the resistance of the wire or something? I have heard somewhere that without the coating a simple wire carries upto 200 amperes but with the coating it can carry only upto 40 amperes max..(hypothetical figures)... is it really posible? and if so...how does it affect? i mean does the thickness of the plastic coatin affect it or is it something else....and is this a well known fact used in the manufacturing of wires or its just a trifle thing?
:With the AI's assistance, I found this article [https://pmc.ncbi.nlm.nih.gov/articles/PMC3324025/ Statistical Mechanics for Natural Flocks of Birds] that states, based on field data, "...interactions are ruled by topological rather than metric distance." Boid models must account for these and other factors. [[User:Modocc|Modocc]] ([[User talk:Modocc|talk]]) 19:12, 17 August 2025 (UTC)
: What sets the limit for how much current a wire can carry is that it gets hotter and hotter the more current you run through it. Too much and it will burn off. If what you've heard is true, it's probably because the coating prevents the heat from escaping into the air and therefore makes the temperature in the wire higher. —[[User:Bromskloss|Bromskloss]] 16:34, 22 June 2007 (UTC)
:The Introduction section of the paper describing the boid model<sup>[https://dl.acm.org/doi/10.1145/37401.37406]</sup> contains this passage:
::Correct. Standard insulation on a wire can melt and start a fire. If there is no coating on the wire and it isn't touching anything, it can get much hotter than it could if it was coated - assuming your goal is to prevent melting the coating. You can think of a filament in a light bulb. Without the coating, it is allowed to get so hot it glows. If you coated it, you would have to cut the current down a lot to prevent the insulation from melting. -- <small><sub>[[User_talk:Kainaw|(¿ʇɐɥʍ)]]</sub></small> [[User:Kainaw|ʍɐuıɐʞ]] 16:37, 22 June 2007 (UTC)
::"The success and validity of these simulations is difficult to measure objectively. They do seem to agree well with certain criteria and some statistical properties of natural flocks and schools which have been reported by the zoological and behavioral sciences. Perhaps more significantly, many people who view these animated flocks immediately recognize them as a representation of a natural flock, and find them similarly delightful to watch."
:In the Conclusion section, the author writes:
::"The animations showing simulated flocks built from this model seem to correspond to the observer's intuitive notion of what constitutes 'flock-like motion.' However it is difficult to objectively measure how valid these simulations are."
:Furthermore, in the description of the model, we read:
::"The flock model presented here is actually a better model of a school or a herd than a flock [of birds]."
:In particular, it appears that natural birds look further ahead than artificial boids, perceiving the approach of a 'manoeuvre wave' and anticipating its arrival.<sup>[https://www.nature.com/articles/309344a0]</sup> So there is no claim, express or implied, that this is a valid model for flocking behaviour, but merely that it looks convincingly similar. It is not a scientific article about animal behaviour but a technological article about a difficult aspect of [[Computer-generated imagery|CGI]].
:While there have been a few studies on the properties of actual biological flocks, these seem to have been with respect, each time, to a single species, reporting the observations in a non-standardized way that makes comparisons of different species almost impossible. How well turning the N and R knobs make the boid-model simulation resemble the natural flocking behaviour of different flocking bird species will depend on the subjective judgement of observers familiar with these specific behaviours. ​‑‑[[User talk:Lambiam#top|Lambiam]] 09:47, 18 August 2025 (UTC)
Thanks both! [[User:Tamfang|—Tamfang]] ([[User talk:Tamfang|talk]]) 23:43, 21 August 2025 (UTC)
::: Oh, apparently I was not entirely correct, then, but not too far from. And you were polite who didn't stab me for it. :-) —[[User:Bromskloss|Bromskloss]] 16:45, 22 June 2007 (UTC)
= August 19 =
::::At extremely high frequencies, such as fiber optics, [[total internal reflection]] can be described as a form of insulation. The relative [[index of refraction]] of the outer ("insulating") layer determines the signal integrity and loss rate. For normal electrical applications, I think the limiting factor is heat, as mentioned above. Plastic or rubber insulation will melt at lower temperature than copper or metal wire. [[User:Nimur|ɹnɯıu]] 17:36, 22 June 2007 (UTC)
== Is the speed of light constant, when measured by a '''remote inertial''' observer, who '''non-locally''' measures a photon traveling a long way in a '''curved''' vacuum? ==
:A few years ago, I recall some electronics engineers in my group specified [[Gore-Tex]]-coated wires for their superior ability to reduce crosstalk between adjacent wires with high speed digital traffic going across them - so I suspect there is more to it than simply preventing the wires from touching each other or other metal surfaces. [[User:SteveBaker|SteveBaker]] 17:54, 22 June 2007 (UTC)
I'm asking, because our article [[speed of light]] states confusingly: {{tq|'''"In non-inertial frames of reference (gravitationally curved spacetime or accelerated reference frames)'''...the speed of light can differ from c when measured from a remote frame of reference".}} This sentence seems to ignore the situation I'm asking about, when the remote observer's frame of reference is '''inertial''', but the spacetime the light travels through is '''curved'''. [[User:HOTmag|HOTmag]] ([[User talk:HOTmag|talk]]) 08:32, 19 August 2025 (UTC)
::Of course! If you are talking about signals, that is completely different than current capacity. I was discussing simple current - shoving little electrons down the wire. Insulation is used to keep the electrons on the wire. In signal wires, you also have to worry about bleed, interference, signal loss... a completely different topic. -- <small><sub>[[User_talk:Kainaw|(¿ʇɐɥʍ)]]</sub></small> [[User:Kainaw|ʍɐuıɐʞ]] 18:07, 22 June 2007 (UTC)
:The length traveled by a photo should be the path length as measured along its curved trajectory, a geodesic of the manifold that is spacetime. I am not sure how you propose the stationary observer is going to measure this. It is in fact not even clear how to ''define'' the path length (in the mathematical model of [[curved spacetime]], a [[Lorentzian manifold]]) with respect to a ''given'', fixed frame of reference. [[Inertial frames of reference]] are useful in special relativity, when objects not acted upon by a force travel in straight lines. Space curvature means that there are no "straight lines", so the inertial model for establishing a reference frame breaks down. ​‑‑[[User talk:Lambiam#top|Lambiam]] 14:07, 19 August 2025 (UTC)
I am very sorry, but when i asked the question, what i meant was actually this- how does the insulation coating affect the amount of current passing through the wire. Like...will there be more current passing without insulation than with insulation? and if so...what is it that exactly determines the amount of current passing?
::Let's assume we (as inertial observers) see a photon travel near the sun in a curved trajectory. Do you claim we can't use any tool (e.g. a telescope or whatever) for measuring the length of this photon's curved trajectory? [[User:HOTmag|HOTmag]] ([[User talk:HOTmag|talk]]) 15:59, 19 August 2025 (UTC)
:::We can detect only photons that arrive at our ___location. If a remote photon interacts with something else in such a way as to cause emission of another photon in our direction, we can detect the resulting photon but we're not directly observing the trajectory of the initial one.
:::Saying "what if as remote observers we see a photon travel near the sun" is like saying "what if as fans watching a soccer match from 10 miles away, we get hit by the ball on its way from the players foot to the goal". A remote observer can't observe a photon's trajectory. -- [[User:Avocado|Avocado]] ([[User talk:Avocado|talk]]) 17:49, 19 August 2025 (UTC)
::::So what does the quote (from Wikipedia) in my original post mean, about when c is "measured from a remote frame of reference"? Doesn't the measurement of c made by a remote observer, mean measuring the ratio between, the photon's trajectory measured by that remote observer, and the time it takes the photon to travel this trajectory - when this time is measured by that remote observer? [[User:HOTmag|HOTmag]] ([[User talk:HOTmag|talk]]) 18:29, 19 August 2025 (UTC)
:::::I'm not a physicist nor the person who wrote the article. I would assume that we can know the time of the photon's origin based on whatever caused it to be emitted also having other effects (gravitational waves, other photons, etc) that reach us directly. And that we can measure the time of the photon's arrival at another point based on the effects of its arrival (reflected or re-emitted light, for instance) that reach us directly. And that we can thus measure the time elapsed between departure and arrival and deduce its speed. But we can't observe its trajectory, only infer it. -- [[User:Avocado|Avocado]] ([[User talk:Avocado|talk]]) 20:15, 19 August 2025 (UTC)
::::::Please note that the condition of "local measurement" (as opposed to "non-local" one) is a well known requirement for the speed of light to be constant. I've asked whether the requirement of locallity of measurement is also needed when the observer's frame of referenece is inertial. [[User:HOTmag|HOTmag]] ([[User talk:HOTmag|talk]]) 06:47, 20 August 2025 (UTC)
:You can imagine that you have a torch in your hand and point it towards a remote black hole. The light from the torch will travel in the direction of the event horizons but will never cross it (from the point of view of an external inertial observer). This effectively means that the speed of light becomes zero in the vicinity of the horizon. However the proper speed of light will remain ''c'' of course. [[User:Ruslik0|Ruslik]]_[[User Talk:Ruslik0|<span style="color:red">Zero</span>]] 20:33, 19 August 2025 (UTC)
::When a photon is approaching a black hole, both the distance traveled by the photon, and the time it takes the photon to travel that distance, approach infinity (from the inertial observer's viewpoint), so the "effective" velocity becomes meaningless rather than "zero". [[User:HOTmag|HOTmag]] ([[User talk:HOTmag|talk]]) 06:47, 20 August 2025 (UTC)
:::Sorry, but the distance cannot become infinite because it is a known quantity. Indeed, you can measure the distance to the black hole and its mass and then calculate the distance to the horizon from the observer.
:The insulation makes no difference to the current, assuming that the insulation is functioning correctly. The above replies are correct: the insulation only affects the current-carrying ''capacity'' of the wire by reducing heat loss. Judging by the wording of your question, you are not talking about advanced applications like radio frequencies or high-precision measurements. --[[User:Heron|Heron]] 20:39, 22 June 2007 (UTC)
:::Actually there is no need to use black holes at all. You can put a mirror on the Earth's surface and direct the laser beam at it from a remote ___location in space. Then since you know the distance and can measure the time when the reflected signal comes back you can calculate the speed by dividing the first quantity by the second. The result will be that the (apparent) speed of light is less than ''c''. [[User:Ruslik0|Ruslik]]_[[User Talk:Ruslik0|<span style="color:red">Zero</span>]] 10:39, 20 August 2025 (UTC)
::As in, those who are shoving electrons down the wire could run it at, for instance, 200 amp, but that will melt the coating and be rather bad. So they are limited to use 40 amp, to not melt it, despite the wiring being able to carry much more. [[User:81.93.102.185|81.93.102.185]] 21:46, 22 June 2007 (UTC)
::::I can see some practical issues with measuring the distance to a black hole. And also some theoretical issues. ​‑‑[[User talk:Lambiam#top|Lambiam]] 16:53, 20 August 2025 (UTC)
:::Assuming the melting/flash point of the insulation is below that of the conductor - yes. But some kinds of insulation (such as the ceramics and other bizarre stuff they use in very high voltage work) might not melt until after the metal inside has melted - in which case the insulation isn't the limiting factor. But for 'normal' stuff - yeah - the limiting factor is that the plastic/rubber/paper insulation melts or catches fire long before the conductor would have given out. [[User:SteveBaker|SteveBaker]] 14:02, 23 June 2007 (UTC)
:::::Any black hole is just a mass. You need only to measure the orbital parameters of test particles moving around it. [[User:Ruslik0|Ruslik]]_[[User Talk:Ruslik0|<span style="color:red">Zero</span>]] 17:34, 20 August 2025 (UTC)
::This is far from the first time I have been exposed to these facts, but this concept still breaks my brain a little. I think it's on account of how we utilize the notion of an observer from an outside frame of reference as an abstraction. Obviously, in terms actual empirical observation at this point, the photon is completely red-shifted and has no chance of ever escaping. So it can't ever be directly observed. And yet we regard it as being unable to ever being able to be observed to have crossed the event horizon. Can someone help me with the structural distinction here? Because obviously if we had a photon's trajectory bent around the gravity well of a black hole (or any mass), we could observe it only by directly interacting with it by intercepting it somewhere along its path. So what do we mean when we talk about observation in an instance that is not in any scenario actually physically possible? ''[[User:Snow Rise|<b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b>]][[User talk:Snow Rise|<sup><b style="color:#d4143a"> let's rap</b></sup>]]'' 06:44, 24 August 2025 (UTC)
:::Just a small remark: '''<span style="color: red">"red-shifted"</span>''' (as you say), only when it tries to ''escape'' a black hole, but here we are talking about a photon ''approaching'' a black hole, so it's '''<span style="color: blue">blue-shifted</span>'''. [[Special:Contributions/2A06:C701:745A:B800:B559:3320:A4F4:C460|2A06:C701:745A:B800:B559:3320:A4F4:C460]] ([[User talk:2A06:C701:745A:B800:B559:3320:A4F4:C460|talk]]) 10:22, 24 August 2025 (UTC)
:::Regardless of their colour (frequency), photons can only be directly observed when they hit the observer. This was already pointed out above by Avocado. They can only be observed, directly or indirectly, when they are detected by some detector, which means in quantum terminology that they are "[[Measurement in quantum mechanics|measure]]d". Measurement of a photon means a change in a macroscopic system (a [[photoreceptor cell]] in the observer's eye, a [[photographic plate]] or [[photographic film|film]], a [[photodetector]], ...) as the result of an interaction with that system. Unless the measuring system is close to where the photon is, the probability of an interaction taking place is vanishingly small. ​‑‑[[User talk:Lambiam#top|Lambiam]] 12:05, 24 August 2025 (UTC)
::::Do you claim, any measurement (e.g. by a telescope or whatever) of the length of a photon's curved trajectory - whether near the sun - or in any phenomenon of gravitational lensing, is a local measurement? [[User:HOTmag|HOTmag]] ([[User talk:HOTmag|talk]]) 13:11, 24 August 2025 (UTC)
:::::Does [[Principle of locality]] help? {The poster formerly known as 87.81.230.195} [[Special:Contributions/90.210.150.115|90.210.150.115]] ([[User talk:90.210.150.115|talk]]) 18:03, 24 August 2025 (UTC)
::::I think you've mis-interpeted my inquiry here, {{u|Lambiam}}. As it happens, I'm a bit of an expert in visual cognition, and so very familiar with the physics/biophysics of photoreceptive media. That's not the part I am struggling to fix in my mind here. My epistemological confusion about the terminology is this: since a photon trapped at the event horizon never escapes to interact with such a medium, what do we mean when we talk about "observation" when, for example {{u|Ruslik0}} says {{tq|The light from the torch will travel in the direction of the event horizons but will never cross it (from the point of view of an external inertial observer).}}? Is it a conceptual conceit/misnomer for describing the relation of the frames of reference? If so, can you think of a thought experiment that would explain those interactions in such a way that accounts for the fact that, as a strictly empirical and ontological matter, no observation at a distance can be made? Maybe Ruslik0 just mixed their metaphors and terminology a bit? If not, I'm super confused as to what the act of observation means in that description. ''[[User:Snow Rise|<b style="color:#19a0fd;">S</b><b style="color:#66c0fd">n</b><b style="color:#99d5fe;">o</b><b style="color:#b2dffe;">w</b><b style="color:#B27EB2;">Rise</b>]][[User talk:Snow Rise|<sup><b style="color:#d4143a"> let's rap</b></sup>]]'' 22:10, 24 August 2025 (UTC)
:::::You are right, I misunderstood the essence of your post. My reaction was triggered by the statement connecting our inability to observe the photon to its colour, which is I think essentially correct – in the model its wavelength tends to zero as it approaches the event horizon – but irrelevant. Scenario's of a photon traveling to an event horizon can be described that conform to a mathematical model of GR, such as [[Schwarzschild metric|Schwarzschild's exact solution to Einstein's equations]]. Such descriptions need a frame of reference, preferably one that in the limit, away from the mass, is an inertial frame. I too think the wording of these scenario's is sometimes confused. The scenario may include an observer for which this frame is stationary who can observe phenomena as predicted by the model, which in real life would validate the model. But such observation can only be through information that reaches them from afar, such as transmitted by electromagnetic waves. An astronaut approaching the event horizon might broadcast a livestream witness report that reaches the observer, but a photon can do no such thing. The models do not allow an observer to observe the unfolding of the scenario with regard to the traveling photon, so describing the scenario in terms of observations is confused. ​‑‑[[User talk:Lambiam#top|Lambiam]] 23:58, 24 August 2025 (UTC)
:::::What I actually meant is [[shapiro time delay]], which can be interpreted as slowing of light in presence of a gravitational field. [[User:Ruslik0|Ruslik]]_[[User Talk:Ruslik0|<span style="color:red">Zero</span>]] 20:33, 25 August 2025 (UTC)
= August 26 =
:::Insulation retains heat, making an insulated copper conductor hotter than a bare one, making it have higher resistance, thereby producing still more heat. It is not a trivial effect, since a conductor might heat up appreciably under normal design loadings. See [[Electrical wiring]] and [[Ampacity]]. [[User:Edison|Edison]] 15:19, 23 June 2007 (UTC)
== Pharmacology ==
== accessory fruit, false fruit, spurious fruit ==
A friend once mentioned a book similar to an Encyclopedia, describing background events behind the development of many well known medicines . Please inform if a similar book can be found and how to "custom search" at any of the sites of WIKI for such a book .
I was looking up the german word "Scheinfrucht" in german-speaking Wikipedia when I realized that no english interwiki was there. In english-speaking WP I found an article on [[accessory fruit]]s and via dictionary I found the terms ''false fruit'' or ''spurious fruit''; to add to the confusion I found ''pericarps'' and ''epigynous berries''. After a quick discussion with native speakers on IRC I guess it's all the same, so I linked "[[de:Scheinfrucht]]" to ''accessory fruit'' and mentioned ''false fruit'' and ''spurious fruit'' and even ''epigynous fruit'' as alternative terms there and created redirects. Now because I'm not 100 % sure about all that I put up this "question" to have somebody check that and change things if my guessing was wrong...
Thnx [[User:Dr chifti|Dr chifti]] ([[User talk:Dr chifti|talk]]) 05:05, 26 August 2025 (UTC)
:You might find such a work used as one of the many references for the article [[History of medicine]], athough what you describe would be a [[Tertiary source]] (like Wikipedia itself) rather than a [[Secondary source]] which Wikipedia prefers for article sources.
Thanks! --[[User:Speck-Made|Speck-Made]] 19:29, 22 June 2007 (UTC)
:Searching Wikipedia for the term "Encyclopedia of pharmacology" led me to the article ''[[Pharmacology Research & Perspectives]]'' whch uses as its reference 4 ''The Sage Encyclopedia of Pharmacology and Society'' – see that article for its bibilographical details. {The poster formerly known as 87.81.230.195} [[Special:Contributions/90.210.150.115|90.210.150.115]] ([[User talk:90.210.150.115|talk]]) 08:04, 26 August 2025 (UTC)
:Searching Archive.org for [https://archive.org/search?query=history+of+medicines history of medicines] turns up many candidates, including [https://archive.org/details/ourmodernmedicin0000band/page/n7/mode/2up?view=theater Our Modern Medicines] (F Bandelin, 1986) which seems to match your description. <span class="nowrap">[[User:Verbarson|-- Verbarson ]] <sup>[[User talk:Verbarson|talk]]</sup><sub>[[Special:Contributions/Verbarson|edits]]</sub></span> 15:04, 26 August 2025 (UTC)
:Looks right [[User:Bendzh|Bendž]]|[[User talk:Bendzh|Ť]] 07:20, 23 June 2007 (UTC)
== can we have non functional Mc1r on purpose ==
i recently read that non-functional Mc1r makes people have red hair, but how is this caused, can it be done on purpose?
:The [[Mc1r]] article describes this gene. This [http://hmg.oxfordjournals.org/cgi/content/abstract/9/17/2531 paper] is fairly incomprehensible to me, but it looks like preliminary investigation into the effect you describe. Perhaps you should try [http://scholar.google.com Google Scholar] ? [[User:Nimur|Nimur]] 01:10, 23 June 2007 (UTC)
:It'd be easier to give a person with red hair the functional MC1R gene, giving them brown/black hair than to replace a functional gene with a non functional gene (give a black/brown haired person red hair). This is generally the case with [[recessive]] characteristics such as red hair. See [[gene therapy]]. [[User:Bendzh|Bendž]]|[[User talk:Bendzh|Ť]] 07:35, 23 June 2007 (UTC)
:: It is not currently technically feasible to "change genes" in humans. In mice, however, it is relatively simple to swap the functional Mc1r for a non-functional Mc1r. Infact, I have done it myself - my lab replaced the mouse gene with a human non-functional Mc1r to see what colour of mouse you get (PMID 11689486) - by a process called [[transgene|trangenesis]].
:: The reason a non-functional Mc1r causes red hair is because it acts as a molecular switch on the surface of [[melanocyte]]s (the cells that produce pigment). A functional Mc1R receives a signal from outside the cell in the form of [[melanocyte stimulating hormone]] and transduces it into the cell. The signal tells the cell to produce [[eumelanin]], which is a black or brown type of melanin. When Mc1r is mutated, it cannot transduce this signal properly and, by a mechanism not yet fully understood, it instead "switches" production to make phaeomelanin, which is red in humans (and yellow in mice). [[User:Rockpocket|<font color="green">Rockpock</font>]]<font color="black">e</font>[[User_talk:Rockpocket|<font color="green">t</font>]] 18:37, 23 June 2007 (UTC)
== Budgerigar/sparrow hybrid? ==
I just removed the following unlikely-sounding paragraph from the [[budgerigar]] article, on account of being unable to find any reference to it using Google.
''"Although highly unusual, in some rare cases a female domensticated budgerigar is known to be capable of mating with a male North American sparrow {{fact}} (particularly the ones in [[Canada]]), thus creating mixed [[sparerigar]] juveniles. However, it is still currently unsure if the sparerigars are anywhere capable of reproducing other cheeks."''
It sounds like BS to me (surely budgies and sparrows are far too distantly related to crossbreed?). Is it BS? Can anyone confirm/deny? Thanks. --[[User:Kurt Shaped Box|Kurt Shaped Box]] 23:12, 22 June 2007 (UTC)
:[[Wikipedia:Attribution|Attribution]] is necessary for inclusion; it also contains a [[neologism]]; as a whole, the paragraph does not make a strong case for inclusion. I can't comment on the factual accuracy, but even if true, it needs sources. [[User:Nimur|Nimur]] 00:41, 23 June 2007 (UTC)
::On the subject of strange animals, the [[necrolemur]] article is in need of a biology/zoology expert. [[User:Nimur|Nimur]] 00:42, 23 June 2007 (UTC)
::: ''Necrolemur'' is [http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Synapsida/Eutheria/Primates/Tarsiiformes/Microchoerinae.htm legit ], but, sadly, [[ extinct | pining for the fjords ]]. As for budgerigar x sparrow, well, that doesn't seem biologically possible; however, I can see how someone watching too much "Pirates of the Caribbean" can get inspired ;). Cheers, [[User:Dr_Dima|Dr_Dima]].
: sparerigar produces not one single Google hit - it's not even a neologism. Extraordinary claims require extraordinary evidence. You can say '2+2=4' without attribution - you can say 'the [[MINI (BMW)|MINI Cooper]] requires 91 octane gasoline' (but we'd prefer to see some kind of a reference to prove it please) but if you want to claim that BigFoot is standing for the Republican party in the next presidential election (not a bad idea actually!) then we're going to need to see some proof in the form of exceedingly solid, credible, references. Without references of any kind, you were 100% correct to remove that paragraph. A mere <nowiki>{{fact}}</nowiki> tag isn't enough for such outrageous claims. [[User:SteveBaker|SteveBaker]] 13:52, 23 June 2007 (UTC)
::Agreed, there can be little doubt this is total BS. These birds aren't just different species, not just different genera, not just different families, but different orders for crying out loud. They evolved on entirely separate continents. A human successfully mating with a [[tamarin]] would probably be more likely. About the only way you'd get a cross between these would be to cut them up and sew the bits together. BTW, the number of spelling mistakes in that paragraph would hardly inspire confidence to start with; oh to see a sparerigar cheek [''sic'']. --[[User:Jjron|jjron]] 16:36, 23 June 2007 (UTC)
= June 23 =
== microorganisms ==
Explain how humans can harbor many microorganisms on and inside their bodies without experiencing symptoms of infectionb[[User:Aspen0212|Aspen0212]] 01:24, 23 June 2007 (UTC)
:I will if you explain why you have the impression that most microorganisms would be expected to cause infections! :) The [[normal flora]] of humans include organisms that seldom if ever cause infection (unless the human host is immunocompromised), and those that cause infection only in special circumstances (breaks in the skin). While it's possible (and usual) for there to be no microorganisms in internal organs, it would be impossible to maintain a sterile environment at the places where the human body and environment meet, because bacteria are ubiquitous. Various mechanisms (mechanical barriers, the human immune system, and bacterial adaptation) allow the microorganisms to exist there without causing disease. Staph bacteria, for example, will be found on nearly every human surface (skin & mucosa). When microorganisms are present but do not cause illness, this is called [[colonization]] rather than [[infection]]. Some organisms are normal flora in one place, and cause infection when moved elsewhere (for example, ''[[Enterococcus faecalis]]'' is normal flora in the bowel, but would be pathogenic in the bloodstream; ''[[E. coli]]'' doesn't cause problems in the bowels, but is a frequent cause of urinary tract infections.) And some microorganisms are actually beneficial; for example, the flora found in the intestines are and are the source of nutrients required for human growth and functioning ([[Vitamin K]] particularly); and the normal flora generally discourage the growth of pathogens. There's additional information on the mechanisms bacteria use to colonize the human body on [http://www.textbookofbacteriology.net/normalflora.html this page]. - <span style="font-family: cursive">[[User:Nunh-huh|Nunh-huh]]</span> 02:37, 23 June 2007 (UTC)
:There are also fungi, such as ''[[Candida albicans]]'', which may cause thrush, but not in all the 80% of people that carry it around in their gut. Even some parasites are very common in people without causing illness, e.g. ''[[Toxoplasma gondii]]''. [[User:Bendzh|Bendž]]|[[User talk:Bendzh|Ť]] 07:59, 23 June 2007 (UTC)
: Think about it from the bacterium's perspective: You get a nice home - it's warm, free from predators, you get fed regularly - and nobody clobbers you with antibiotics or evolves a means to flush you out '''''providing''''' that you don't make a nuisance of yourself! So these critters have evolved not to do bad things to us - and in some cases to be beneficial to us in order to survive and do what they do best. It's very much NOT in the bacterium's interest to kill off it's host - and the really nasty bugs are generally the ones that have only recently (in evolutionary terms) managed to cross over into our species and have not yet evolved a way to not be quite so harmful. It's well known that the lethality of various bacterial strains declines over time as the bacteria evolve. From the point of view of the bacterium, there is no benefit to causing your host to die - leaving you buried 6' underground in a nice wooden box or cremated! The bacteria (and virus strains) that DO cause symptoms - generally do so for a reason (eg when you sneeze because you have a cold - that's helping to spread the common cold virus - so that symptom is in the interests of the virus). It's just an evolved behavior. [[User:SteveBaker|SteveBaker]] 13:44, 23 June 2007 (UTC)
== pH - 2 little questions ==
Hi all,
Could you please explain my two little things about acids? Would be great - it's for an exam on monday...
1) Which formulae do you use to calculate the proportion of the protonated form of the acid when you have the pKa of the acid and the pH of the environment?
2) Which formulae do you use to know the pH of the mix KH2PO4 0.01 M + K2HPO4 0.01 M ?
Thanks very much in advance!!!
:See [[Henderson-Hasselbalch equation]]. [[User:Icek|Icek]] 14:32, 23 June 2007 (UTC)
== Seeing what isn't there. ==
Can someone give me the name of the effect, where you see something, like the virgin mary, that's not really there?--[[User:Honeymane|<font color="red" face="Old English Text MT, Papyrus">Honeymane</font>]]<sub>[[User_talk:Honeymane|<font face="Klingon, QuigleyWiggly">Heghlu meH QaQ jajvam</font>]]</sub> 08:14, 23 June 2007 (UTC)
:I assume you're talking about the situation where you look at something with a complex random texture, like a cloud or a hillside or a piece of food, and the texture seems to form a shape: a sort of [[optical illusion]]. I didn't find this one in the [[list of cognitive biases]] (the nearest thing there is the [[clustering illusion]]), so I looked at the page for a specific example, the [[Face on Mars]], and there was a link to the answer: [[pareidolia]]. (If I'd thought of looking under [[perceptions of religious imagery in natural phenomena]], it would have let me to [[pareidolia]] straight away.)
:On the other hand, if you mean the sort of "seeing things" that has to do with your brain malfunctioning, like you look at what everyone else sees as a blank wall and you see (or hear) the Virgin Mary standing there talking to you, that's a [[hallucination]]. --Anonymous, June 23, 2007, 09:20 (UTC).
:: We might also mention the [[Rorschach inkblot test]]. (Oh, wait, never mind, the aforementioned [[pareidolia]] article already does.) —[[User:Ummit|Steve Summit]] ([[User talk:Ummit|talk]]) 18:54, 23 June 2007 (UTC)
I'm also reminded of this little bit of computer doggerel:
: If you can see it and it's there, it's [[real]].
: If you can see it and it's not there, it's [[virtual]].
: If you can't see it but it is not there, it's [[transparent]].
: If you can't see it and it's not there, it's [[imaginary]].
—[[User:Ummit|Steve Summit]] ([[User talk:Ummit|talk]]) 20:48, 23 June 2007 (UTC)
== Boeing 747 and Airbus ==
Could you please tell me the advantage and disadvantage of '''Boeing 747''' and '''Airbus'''? Which one is the best? Why?
I will be gladful if you could answer this question as soon as possible. ^ ^
:They can fly really fast, but make a nasty kaboom when they crash? [[User:Splintercellguy|Splintercellguy]] 10:33, 23 June 2007 (UTC)
::One is made in US, one is made in Europe. Airbus is currently experiencing some problems with their A380 and will take a while to recover while Boeing seems to have snapped out of their technological disadvantage and now on track with their new 787. --[[User: Antilived|antilived]]<sup>[[User_talk:Antilived|T]] | [[Special:Contributions/Antilived|C]] | [[User:Antilived/Gallery|G]]</sup> 10:41, 23 June 2007 (UTC)
:::First of all, I should clarify that [[Airbus]] is the company, not the aircraft. Presumably you're referring to the [[Airbus A380]] which is the closest competitor to the 747. In real terms (disregarding production delays with the A380), neither aircraft is "better" than the other and a direct comparison isn't especially helpful. The [[Boeing 747]] is an old design, having first flown in 1969. However it's been continuously upgraded and the latest version, the 747-8, is intended to be significantly more efficient (and larger) than previous incarnations. You might consider that Boeing has the benefit of huge experience with this aircraft, while the A380, being new, is having some teething difficulties. On the other hand, the A380 is brand-new, larger than the 747 and with significant potential for enlargement (whereas the 747-8 is pretty much as big as the 747 can get AFAIK, there are plans for A380s to carry up to ~1000 passengers). Really, which one is the "best" for a particular airline will depend very heavily on what they intend to do with it - mostly this comes down to finding the lowest-cost way of serving their intended routes and customer groups. That in turn will depend on what sort of deal they can work out with the manufacturer - some of the early A380 adopters will have got excellent prices for their aircraft because Airbus want to have prestigious airlines using their planes to get the order book rolling. If you're in the position to ''need'' to know which of the two is "best", I'd hope you'd have enough appreciation of the airline industry to realise that it's much, much more complicated than your question suggests. There isn't a simple answer, I'm afraid. --[[User:Yummifruitbat|YFB]] [[User talk:Yummifruitbat|<font color="33CC66">¿</font>]] 11:03, 23 June 2007 (UTC)
:::: What do you mean, there "isn't a simple answer"? I mean, ''obviously'' Boeing is better than Airbus, just like [[Ford]] is better than [[Chevy]], [[Boston]] is better than [[New York City|New York]], [[emacs]] is better than [[vi]], [[Macintosh|Mac]] and [[Linux]] are better than [[Microsoft Windows|Windows]], [[C (programming language)|C]] is better than [[C++]] and [[Java (programming language)|Java]], and [[Bass Ale]] is infinitely better than [[Miller Lite]]. —[[User:Ummit|Steve Summit]] ([[User talk:Ummit|talk]]) 12:47, 23 June 2007 (UTC)
::::: Wow! Excellent answer - except for one teeny-tiny typo: ''[[emacs]] is better than [[vi]]'' - you ''obviously'' mean "worse"...oh - and see, you made the same mistake with [[C]] and [[C++]]. (Oh - and Bass is not merely '''''infinitely''''' better than Miller - we actually need to use one of the higher [[Aleph number]]s to express the infinity we're referring to!) [[User:SteveBaker|SteveBaker]] 13:35, 23 June 2007 (UTC)
:If a [[celebrity endorsement]] will help you decide, [[John Travolta]] [http://www.france24.com/france24Public/en/administration/afp-news.html?id=070621173906.r9tckuk6&cat=null likes the Airbus.] But he ''owns'' a [[Boeing 707|Boeing]]. [[User:Anchoress|Anchoress]] 15:25, 23 June 2007 (UTC)
The Airbus may be too big. It requires airport modifications to accommodate it, in many cases, and very few routes can support a plane that large. For example, if you wanted to fly from [[Albany]], [[New York]] to [[San Diego]], [[California]], using the A380, you would need to fly from Albany to [[New York City]] on a smaller plane, then from NYC to [[Los Angeles]] on the big A380, then from LA to San Diego on a smaller plane. Who would want to do that ? [[User:StuRat|StuRat]] 16:34, 23 June 2007 (UTC)
== differential gear(battle tank, wheel chair) ==
for turning, in four wheelers we have differential gear,in rikshaw (3wheeler,pulled by a man)we have a wheel free.what arrangement is there in battle tanks and wheel chairs?[[User:59.92.5.237|59.92.5.237]] 11:08, 23 June 2007 (UTC)
:In tanks and other tracked vehicles, there is no need for a differential - the vehicle is steered by disengaging a clutch on one side or other of the vehicle - so one track stops moving and the tank skids around. With electric wheelchairs, each of the two rear drive wheels has a separate electric motor - and they steer by slowing down one or other of the motors - so again, no differential is required. [[User:SteveBaker|SteveBaker]] 13:31, 23 June 2007 (UTC)
::A tank could turn by powering only one track, but this would result in it travelling in a circle around the center of the nonpowered tread. Modern tanks such as the Abrams actually power the treads in oposite directions, allowing them to spin in a circle with the center of the tank as the center of rotation. This would be a big advantage in combat, if they needed to turn around to face an enemy behind them (there is usually thicker armor on the front of the tank)in a street too narrow for the other wider turn. [[User:Edison|Edison]] 14:59, 23 June 2007 (UTC)
== the old relativity pole and barn paradox with a twist ==
Imagine there is a 10 meter pole on the ground and a 5 meter long barn. Imagine there are two persons, superman and barney the barn manager. Imagine superman runs from left to right going through the barn.
Now superman made barney promised that barney would do the following in the correct sequence.
:(1) Open both barn doors (left door and right door)
:(2) Signal to superman to pick up the 10 meter pole and start running.
:(3) Wait for superman to run
:(4) Close the right hand side barn door
:(5) Wait for superman to enter the barn
:(6) Close the left hand side barn door
:(7) Take a picture of the barn
:(8) Open the right hand side barn door
:(9) Watch superman runs out of the barn with the pole through the right hand side barn door.
So far so good. Imagine that superman ran so fast that according to barney the pole has shrunk from 10 meters to 1 meters. While according to superman the length of the barn has shrunk from 5 meters to 0.5 meters.
The paradox is that barney will ONLY open the right hand side barn door AFTER he has closed the left hand side barn door. And once barney closed the left hand side barn door, he will never ever opens it up again.
So the question is this. According to superman, where is superman at the exact moment barney has closed the left hand side barn door?
[[User:210.49.223.231|210.49.223.231]] 11:55, 23 June 2007 (UTC)
: I know he's a busy guy but could we ask Mr Superman nicely if he'd please do it again? But with a 10m ladder instead? If so, then we have an article explaining the whole thing - it's called 'The [[Ladder paradox]]'. The problem with your description is that the concept of 'simultaneous' does not exist in a relativistic world. In our normal experience, this doesn't matter - but when superman is moving almost as fast as light, it becomes very important. Anyway - read the article - it explains the whole thing very well. [[User:SteveBaker|SteveBaker]] 13:15, 23 June 2007 (UTC)
:This works only if Barney has got an assistant. Barney is at the right door, the assistant is at the left door, and they have synchronized their clocks. Then the events of closing the left door and opening the right door are [[spacelike]]ly separated and the order of the events depends on the system of reference. [[User:Icek|Icek]] 14:23, 23 June 2007 (UTC)
:: That is nothing we have to care about – it doesn't alter the problem. Just imagine there was an assistant, if you want. —[[User:Bromskloss|Bromskloss]] 17:40, 23 June 2007 (UTC)
:::If he doesn't have an assistant, it can't happen because Barnie needs to travel faster than light to get from one door to the other in less time than Superman does. [[User:SteveBaker|SteveBaker]] 17:43, 23 June 2007 (UTC)
:::: Of course. But we shouldn't get stuck on that, since it is not the point of the thought experiment. —[[User:Bromskloss|Bromskloss]] 17:49, 23 June 2007 (UTC)
== heart attack ==
Where can I find statistical distributions for the times of day, i.e., getting ready for bed, being asleep or waking up and getting out of bed that proceed a heart attack most often? For instance does a heart attack occur more often in the evening before bed or in the morning before waking up or after going to bed or after waking up? I need statistical distributions on anything and everything surrounding a heart attack. [[User:71.100.3.132|71.100.3.132]] 14:21, 23 June 2007 (UTC)
:If you do a [http://search.medscape.com/medline-search?newSearch=1&queryText=myocardial+infarction+diurnal Medline search] on "myocardial infarction" & "diurnal", you'll find about 125 references. "Onset of acute myocardial infarction (AMI) follows a diurnal periodicity, with a peak incidence between 6:00 a.m. and noon. " (Impact of Ramipril on the Circadian Periodicity of Acute Myocardial Infarction, ''The American Journal of Cardiology'', Volume 98, Issue 6, 15 September 2006, Pages 758-760) - <span style="font-family: cursive">[[User:Nunh-huh|Nunh-huh]]</span> 15:15, 23 June 2007 (UTC)
== car batteries ==
how to find the amount of lead sulphate formed in the paste experimentally? (for a lead acid battery) .[[User:Ruvini|Ruvini]] 15:09, 23 June 2007 (UTC)
== Cloud brightness ==
Why are some clouds pure white, and others are darker, even black?
See [[Cloud#Colors]]. [[User:Skarioffszky|Skarioffszky]] 17:58, 23 June 2007 (UTC)
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