Wikipedia:Reference desk/Archives/Science/2016 March 19

= March 19 =

Name for type of spring
What's the name for this kind of "pyramid-shaped" spring?

In case there's no special name for it, what's best keywords that I can use find it on eBay or Amazon? I tried "pyramid shaped spring" but it doesn't do the job. Johnson&#38;Johnson&#38;Son (talk) 06:35, 19 March 2016 (UTC)
 * "Conical spring" or "tapered spring" find lots of them on google. DMacks (talk) 06:54, 19 March 2016 (UTC)
 * A similar spring is sold in Sweden & Norway as a "Tankspiral" whose description translates as Effectively stops the petrol thief. Prevents theft by hose of fuel via the filler pipe. Easily mounts in the fuel filler pipe. AllBestFaith (talk) 13:15, 19 March 2016 (UTC)
 * It's a "conical" or "tapered" spring. If there was such a thing as a "pyramid-shaped spring" it would have a bunch of square corners.  The geometric shape that's a circular shape that gradually tapers to a point is called a "Cone" - hence "conical spring".   A spring that actually did have square corners wouldn't work very well because all of the twisting force would end up concentrated in the corners. SteveBaker (talk) 16:53, 19 March 2016 (UTC)
 * The spring in your Picture does not have a standard, common form nor does it look like a common spare part so no Wonder you can not find it online anywhere. Manufacturers who use such special formed springs will order them as mass product from specialized companies that massproduce such springs in almost any form you order. Then the ordering Manufacturer usually gives it a functional name in context of its use. --Kharon (talk) 16:53, 19 March 2016 (UTC)
 * Did you even read AllBestFaith's post (above) which seems to be the best description yet? Akld guy (talk) 04:51, 20 March 2016 (UTC)
 * The original poster may have a larger size in mind, but conical springs are very common in battery compartments for the common sizes AAA, AA, C, and D. They are typically used as the negative contact and also press the battery against the positive contact.  See this one and this one and this one, and this one, for example.
 * Curiously, the article spring (device) includes a red link to "conical spring" but outside of that passage it uses the phrase only in a single sentence, which is garbled. However, coil spring includes illustrations of conical coil springs. --69.159.61.172 (talk) 07:25, 20 March 2016 (UTC)
 * @Akld guy Again, there is no standard on conical springs. Not form nor size nor material. Any such spring is proprietary. So bite me :p. --Kharon (talk) 22:30, 21 March 2016 (UTC)

Did a cheapness always allows to satisfy much needs of more people?
Did a cheapness always allows to satisfy much needs of more people?--83.237.192.157 (talk) 09:36, 19 March 2016 (UTC)

So, did a cheapness of electricity and natural gases allows to satisfy much needs of more people?--83.237.192.157 (talk) 09:45, 19 March 2016 (UTC)
 * It sounds like you're talking about Supply and demand. Ian.thomson (talk) 10:04, 19 March 2016 (UTC)
 * I don't know. Did a combinations of electricity and natural gases always allows to save an electricity and natural gases?--83.237.192.157 (talk) 10:24, 19 March 2016 (UTC)
 * So, did technical methods - technical levels of application and use are makes a cheapness?--85.141.236.80 (talk) 11:10, 19 March 2016 (UTC)
 * So that, did technical methods - technical levels of application and use are makes a economy?--85.141.236.80 (talk) 11:13, 19 March 2016 (UTC)


 * Please try and write clearer English. There's no such thing as 'a cheapness'. And there's a difference between 'an economy' - the whole financial situation of a country or other entity - and 'making economies' - making savings. AlexTiefling (talk) 11:23, 19 March 2016 (UTC)
 * Thanks. It seems me, that the levels of complexity of technique are always decides all.--85.141.236.80 (talk) 11:28, 19 March 2016 (UTC)
 * It is necessary to identify cases in which the levels of complexity of technique are not decides all.--85.141.236.80 (talk) 11:37, 19 March 2016 (UTC)


 * Did the most simplest technical approach to application and use of natural gases is justified in my country USSR-Russia?--85.141.232.111 (talk) 12:20, 19 March 2016 (UTC)


 * We can not understand you. Please try [ https://ru.wikipedia.org/ ]. --Guy Macon (talk) 12:28, 19 March 2016 (UTC)


 * I'm try again. If technical methods - technical levels are allows to economy, did the most simplest technical approach of application and use of natural gases makes a cheapness?--85.141.232.111 (talk) 13:17, 19 March 2016 (UTC)


 * Did technogenesis of economy of the USSR-Russia is insufficient?--83.237.222.31 (talk) 15:16, 19 March 2016 (UTC)

PLEASE NOTE: We are not understanding your questions because either your English isn't good enough - or you're using a bad translation service. You need to ask your question on the Russian Wikipedia Help/Reference desk. We can't help you here. SteveBaker (talk) 16:49, 19 March 2016 (UTC)
 * If the question were coming from France or Esperantujo, I'd invite them to ask in their first language and I'd translate. —Tamfang (talk) 23:57, 20 March 2016 (UTC)


 * Thanks for your help. Of course, a technogenesis of economy of the USSR-Russia did small, I think it did so, because economy of the USSR-Russia did using a natural gases and did saving an electricity and natural gases, that it is what about I’m did interesting here.--Alex Sazonov (talk) 18:28, 19 March 2016 (UTC)


 * When a commodity becomes cheaper, people can afford proportionally more of it. However, people who compete to produce that commodity lose all income once the price decreases below their cost of production.  For example, as described by the Zapatistas 20 years ago, and recently discovered by some Trump-leaning media in the U.S., the availability of federally subsidized corn from the U.S. via NAFTA caused indigenous peasants in Mexico to lose their ability to support themselves on their land, driving them to the cities and in turn driving the workers they displaced into the U.S. as illegals, where they displaced yet others... there are many solutions suggested for problems like this, provided that they involve neither the repeal of corn subsidies nor the repeal of NAFTA. Wnt (talk) 21:33, 19 March 2016 (UTC)
 * Did it makes sense to economies its development, that is did it makes sense to economies a development of its technogenesis? My country USSR-Russia did making economies its development, because its economy did using a natural gases and did saving an electricity and natural gases.--83.237.207.51 (talk) 11:27, 20 March 2016 (UTC)
 * It more always depends on to economies on or to economies its.--83.237.207.51 (talk) 13:14, 20 March 2016 (UTC)
 * So that, what technogenesis leads to a cheapness, it’s a small or high technogenesis?--83.237.207.51 (talk) 14:30, 20 March 2016 (UTC)


 * New technology often makes a commodity cheaper; for example, John D. Rockefeller made himself rich by making oil cheaper by new techniques of extraction and refining. On the other hand, a change in the relative prices of two or more commodities can make a technology (new or old) more practical. —Tamfang (talk) 23:59, 20 March 2016 (UTC)
 * Thanks a lot! Did the banking on natural gases justified in my country USSR-Russia, that is did the most simplest technical approach of application and use of natural gases justified in my country USSR-Russia, if a cheapness did not come to my country USSR-Russia? Maybe a cost of natural gas always decides all, so that maybe a cost of natural gas is too high?--85.141.237.148 (talk) 08:14, 21 March 2016 (UTC)

Sword-billed hummingbird preening
The Sword-billed hummingbird has a bill longer than its body. How does it preen itself? (Please feel free to add the answer to the article). Andy Mabbett ( Pigsonthewing ); Talk to Andy; Andy's edits 12:08, 19 March 2016 (UTC)


 * [ http://astronomy-to-zoology.tumblr.com/post/43434261341/a-sword-billed-hummingbird-ensifera-ensifera ] has a video of a sword-billed hummingbird preening with his feet. --Guy Macon (talk) 12:31, 19 March 2016 (UTC)
 * You just beat me, Guy. Here's another: . Excellent question, Andy!  S n o w  let's rap 12:37, 19 March 2016 (UTC)
 * Also *cough* that detail is already found in the article. ;) Still glad you asked though. Every day you learn a new ornithological fact is a day you are a little closer to nirvana. :D  S n o w  let's rap 12:43, 19 March 2016 (UTC)

Thanks you, all. I missed that in the article, because I searched for the string "preen". I've fixed it now. Andy Mabbett ( Pigsonthewing ); Talk to Andy; Andy's edits 16:06, 19 March 2016 (UTC)
 * Hi all. Great question.  Loved the videos.  Do we have a policy/guideline on inserting a link to videos (I am thinking only of animal behaviour here) within the text, rather than "External links" section?  This may not be the place to raise this question - it it is not, where might this place be? DrChrissy (talk) 15:15, 21 March 2016 (UTC)
 * I just read WP:External links which explains this. Please disregard the question. DrChrissy (talk) 15:38, 21 March 2016 (UTC)

Serial Wire Debug Port
I'm looking for the simplest Serial Wire Debug port pinout possible. The best one I've found (best in terms of minimal pins) so far is this 10 pin version.

1. How come all these SWD pinout are so needlessly complex? Doesn't SWD just have two data pins? Ground, Vcc, and the two data pins would be only 4 pins in total. All the pinouts I've found are at least double that.

2. Is there a common-ish SWD header that's less than 10 pins?

3. I noticed that the standard 10 pin SWD header has a reset pin. Is this actually necessary? Doesn't the SWD protocol already implement a reset command? Or does this reset pin serve as a backup hard reset as opposed to the SWD's soft reset? Johnson&#38;Johnson&#38;Son (talk) 15:37, 19 March 2016 (UTC)


 * These are the only pins required:


 * Clock
 * Data (2-way)
 * Ground

In the question above, you assumed that power was required, but it is not.


 * These are optional, but often useful:


 * Power to target
 * A second ground pin to reduce noise
 * Reset target
 * Serial Wire Output - not required but allows extra trace capabilities
 * Target reference voltage - voltage from target that sets the output logic levels sent to the target (avoids feeding 0-5V signals to a board that is expecting 0-3.3V...)
 * Key - unused pin to prevent connector being plugged in backwards.
 * Various extra signals so that the same connector supports SWD and JTAG.


 * A reset pin will hard reset a hung/crashed system. A reset command assumes that the system is working well enough to receive the command. --Guy Macon (talk) 16:40, 19 March 2016 (UTC)


 * If you are designing a board, I recommend using one of the connectors listed here: [ http://www.keil.com/support/man/docs/jlink/jlink_connectors.htm ]. While there are no real standards, those three are fairly widely used. --Guy Macon (talk) 16:59, 19 March 2016 (UTC)


 * The article you linked to covers all of this. It says "There are no official standards for JTAG adapter physical connectors." - so your idea that this is a "standard 10 pin header" isn't correct.  It also says: "Those connectors tend to include more than just the four standardized signals (TMS, TCK, TDI, TDO). Usually reset signals are provided, one or both of TRST (TAP reset) and SRST (system reset). The connector usually provides the board-under-test's logic supply voltage so that the JTAG adapters use the appropriate logic levels. The board voltage may also serve as a "board present" debugger input. Other event input or output signals may be provided, or general purpose I/O (GPIO) lines, to support more complex debugging architectures."
 * The actual "serial debug" part of the JTAG interface is indeed just two wires - TxD,RxD (with an "assumed" common ground connection) - but when you're debugging a circuit with a JTAG instrument, you generally want to do other things - supplying power, ground and a system clock and doing a hard-reset on the system are obvious requirements.
 * The article also lists the common connector types with the numbers of pins - so the article also answers (2).
 * So if you're using a standard JTAG tester - you'll need to follow whatever pinout it demands. If you're inventing your own JTAG debugger (or using the serial standards of JTAG for something else) - then two wires plus ground will suffice - and then you're at liberty to use any 2 (or preferably 3) pin connector you want. SteveBaker (talk) 16:44, 19 March 2016 (UTC)

Do you need to burn fuel to decelerate a spaceship when landing?
Couldn't you just reach a planet parallel and in the opposite direction of its orbit, moving in a parabolic arc, and then land softly? You'll need a precise calculation, but that would reduce the amount of fuel you need for your rocket.--Scicurious (talk) 18:02, 19 March 2016 (UTC)


 * The laws of physics run backwards just the same. If what you said could happen then things on the earth could just lift off and go into space without fuel. Dmcq (talk) 18:30, 19 March 2016 (UTC)


 * I am not sure that's the same case backwards. In my scenario the spaceship approaches a planet and has lots of kinetic energy and the planet brakes it due to its gravity. In the inverse scenario, energy could not just appear to accelerate an object and escape the surface of a planet. --Scicurious (talk) 18:36, 19 March 2016 (UTC)


 * You can land on a small asteroid with zero extra fuel but you cannot just reach a planet already stopped. The planet has a gravity well and any inert object going down gains many kilometers per second speed whether it wants to or not. It is possible to land with zero fuel with a skip reentry and then parachutes (and airbags if needed). Sagittarian Milky Way (talk) 19:16, 19 March 2016 (UTC)


 * The "laws of physics are reversible" argument should be usable to reverse the ever-popular "slingshot manouver" - used to speed up a spacecraft by stealing some kinetic energy from a suitable planet. I have no idea how - but it seems like this should be able to slow you down...somehow. SteveBaker (talk) 01:25, 20 March 2016 (UTC)


 * I believe a slingshot works because the ship approaches the planet slowly, and thus has it's gravity act on it for a long time, to accelerate it, then leaves the planet quickly, thus having less time for the planet's gravity to act on it to decelerate it. To reverse that, I'd expect you would need to reverse the force of gravity.  However, skimming the atmosphere might work to slow it down so it leaves to planet more slowly, so you could perhaps get a reverse slingshot that way, if you could slow it down more than it accelerated as it approached the planet. StuRat (talk) 01:45, 20 March 2016 (UTC)


 * If you imagine the planet and spaceship as hard, elastic objects like billiard balls, and if there is no atmospheric braking involved/ then a slingshot maneuver produces exactly the same results as if the spaceship simply bounced off the planet. This is a necessary result of the conservation of energy and momentum.  The reason that these maneuvers are sometimes useful is that we can choose where in the planet's orbit the spacecraft will approach it, and therefore which way it will "knock" the spacecraft.  The only reasons to go around the planet instead of bouncing off it are the important facts that planets and spaceships are not hard, elastic objects and that there may be an atmosphere that you usually want to avoid. --69.159.61.172 (talk) 07:39, 20 March 2016 (UTC)
 * Not necessarily from one planet to the next. It's a question of rotational speed and timing the tangent, lagrangian point and rotation of the other body.  You would need to slow down enough from the leaving body (or passing body so the velocity imparted by the arriving body matched its rotational speed.  It's easier calculate if you don't worry about the launch bit. How far away from a planet without an atmosphere does spaceship have to be to reach the same rotational speed as the body.  It's tricky because as was pointed out, it accelerates into the body and the precise point it reaches rotational velocity it has to be at the surface or crash or miss.  --DHeyward (talk) 02:54, 24 March 2016 (UTC)


 * This is implied by what 69.159.61.172 wrote, but to make it clear, you can use a slingshot maneuver to slow down, but not relative to the object you're slingshotting around, only relative to some other object. (And even if you use a slingshot around some other planet to slow to near rest relative to the planet you want to land on, you will still hit the surface at roughly the escape velocity if there's no atmospheric friction and you don't fire your rockets.) -- BenRG (talk) 09:12, 20 March 2016 (UTC)
 * Aha! "not relative to the object you're slingshotting around" - thanks!  Very perceptive answer.  SteveBaker (talk) 15:32, 20 March 2016 (UTC)


 * With a thick atmosphere or oceans, those can be used for deceleration, but the tricky part is not destroying the ship in the process. StuRat (talk) 20:05, 19 March 2016 (UTC)


 * The problem with a parabola is that the arc is level at the point of release and not level at the point of impact. Things are stationary when you let go of them, not when they hit the ground; and if shot up from the ground, they become stationary at some point in mid-air (assuming they don't get to orbit).  To put it another way, the speed decreases when it is a speed upward against a downward acceleration, but it increases when it is a speed downward added to more downward acceleration.  So there is no way to plot the orbit to land softly on the planet, though of course a clever glider (aka "flying brick", as the Space Shuttle was lovingly called) could make use of the air to slow down and control a landing. Wnt (talk) 21:12, 19 March 2016 (UTC)


 * As our gravity assist article explains, you can indeed use it to slow down -- just go round the planet the other way. Aurora (novel) has a fictional example (which also includes some hardcore aerobraking. HenryFlower 07:24, 20 March 2016 (UTC)

The short answer to the original question is that you can't do this because the planet's gravity always pulls you toward the planet. As soon as you reach a position where you are moving toward the planet, it will therefore accelerate you toward it. In fact, if the planet has no atmosphere and you reach it without rocket or similar propulsion, you will always crash-land at the planet's escape velocity or faster. --69.159.61.172 (talk) 07:32, 20 March 2016 (UTC)

Actually you can. There are many points such as the lagrangian, geostationary, slingshot, etc, that all use gravity to maintain position. The trick is the large body like earth has air and friction. Without that, you could conceivably time your entry velocity so that you met the rotational velocity at the surface. That's about 1,000 mph at the surface and space vehicles slow down to that velocity so the land where they want. You would need another body to slow down the craft to hit proper entry so that your velocity into the well matched the rotation. This was huge in free return paths from the moon and missing that entry azimuth and velocity meant death. Apollo ships did not need propellant to return to earth and their paths were designed so they could suffer primary and secondary propulsion and still enter the atmosphere at the correct angle and speed. Now, an atmosphere that travels at roughly the same rotation as the body makes it a heat problem to solve. Take atmosphere away but still have a rotating body, it's a needle in a haystack. There is a solution but it's not very error friendly. People don't survive crashes at high speed and matching rotation could be nasty when the surface is moving 1000 mph relative to the fixed stars. Here's a NASA paper regarding their launch windows for Apollo and choices they made. In missions where they inserted into lunar orbit the mechanics were a bit different than free return figure 8 (a la apollo 13). --DHeyward (talk) 02:29, 24 March 2016 (UTC)
 * To be a little clearer, landing on the moon with no atmosphere would be very difficult because it's tide locked with earth and rotates once in 28 days (very slow). You would have to using something like jupiter or the sun to slow you down, hope there was tangent where the sun/planets didn't take over (or the earth).  That solution may not exist depending on mass, lagrangian points and other things.  And no there is no equation, it's numerical.  --DHeyward (talk) 02:41, 24 March 2016 (UTC)

Ritalin, similar chemically similar to cocaine?
Is Ritalin very close to cocaine? Does it matter if you are trying to estimate the effect of it? After all, two substances can be chemically very close, but have, biologically, a completely different effect on an organism? Ignoring social taboos relating to cocaine use, would it be feasible to substitute therapeutic Ritalin use for cocaine? --Llaanngg (talk) 18:21, 19 March 2016 (UTC)


 * Some similar chemicals act biologically identical, while others behave quite differently (for example, if the difference is in the "key" which allows it to enter your cells). StuRat (talk) 20:02, 19 March 2016 (UTC)


 * Neither Ritalin nor cocaine need to enter cells to have their effects. Fgf10 (talk) 23:07, 19 March 2016 (UTC)


 * My response was to the 3rd Q, which doesn't ask about specific drugs. StuRat (talk) 23:28, 19 March 2016 (UTC)


 * See Ritalin and cocaine. The trouble with saying "similar" is that, except in extreme similarity, it can be a bit arbitrary.  I mean, on both structures you'll see a phenyl ring and a six-membered ring with five carbons and a nitrogen (piperidine) and an ester somewhere near where the two meet.  But is that 'close enough to matter'?  Usually it is more academically defensible to speak of the known activities of the drugs ... caveat being that these activities tend to be some of the most remarkably revised bits of scientific fact you can hope to run across, with different types of activity on different (usually newly discovered) receptors becoming the target of research from one decade to the next.  I'm not sure there's any completely satisfactory way to look at this, however intuitive and meaningful the approach may be!
 * In terms of treating cocaine withdrawal with ritalin, I didn't see much - one thing I found was this abstract, which if I read it correctly is saying that ritalin actually increases cocaine cravings among those doing without it. I'm not sure I searched for this correctly however; there are some specialized terms about addiction that I cannot presently recall. Wnt (talk) 21:24, 19 March 2016 (UTC)
 * From a quick scan of the articles, they are both dopamine reuptake inhibitors. I wouldn't be surprised if the structural similarities you mention are the common cause of that, but I'm way out of my depth. --Trovatore (talk) 21:26, 19 March 2016 (UTC)
 * has a section about methylphenidate analogues. DMacks (talk)

Evolution vs. the Second Law of Thermodynamics
I've heard that evolution violates the second law of thermodynamics. Is that true? Bonupton (talk) 21:01, 19 March 2016 (UTC)


 * I heard it more generally that life does. That is, life is about increasing the order of the universe, which counters the general trend.  I compare with the conservation of energy law, which states that energy can never be created or destroyed.  That's not the full story, though, as mass can be converted to energy, according to E = mc2.   StuRat (talk) 21:06, 19 March 2016 (UTC)


 * I linkified your title. StuRat (talk) 21:07, 19 March 2016 (UTC)


 * See Entropy and life and Objections to evolution for our articles on the subject. Tevildo (talk) 22:15, 19 March 2016 (UTC)


 * It might actually be that life and evolution are results of the second law of thermodynamics. ←Baseball Bugs What's up, Doc? carrots→ 22:39, 19 March 2016 (UTC)


 * In short: No, evolution does not violate thermodynamics. You could substitute any production of apparent order for evolution - building a brick wall, or sorting a disordered drawer, would qualify too. In every case, the local or specific appearance of order is the result of processes which expel a lot of energy as heat, thus increasing the overall entropy of the universe. AlexTiefling (talk) 22:41, 19 March 2016 (UTC)


 * Note that both those examples are performed by life. There may be some non-life examples, though, such as the formation of crystals, which appear to be more orderly than the random arrangements they came from.  Or does that imply that crystals, which can grow & reproduce, are alive ?   Certain weather phenomenon, such as hurricanes, also seem more orderly than what pre-dated them, and the formation of a solar system or galaxy may qualify, too (and a galaxy would seem to qualify as a"closed system").   So, the tendency of everything towards a more disordered state seems like a rule of thumb, more than a law, to me.  StuRat (talk) 23:22, 19 March 2016 (UTC)


 * That cup of coffee cooling on your desk is becoming more orderly by the second. Admittedly from your interest in domestic hygiene that may be due to living organisms, but to the engineer who has learned these things, a hygienic cup of coffee becomes more orderly but the surrounding atmosphere becomes less orderly at the same time, by a greater or equal amount.Greglocock (talk) 07:50, 20 March 2016 (UTC)


 * There's an interesting counter-example when artificial sweeteners are stirred into coffee. Since they are much more powerful, they frequently use silicon dioxide (quartz sand powder) as filler.  It doesn't dissolve in the coffee, but rather stays in suspension for some time after the stirring motion.  If left to sit, however, it settles out on the bottom.  So, in this case, life (the person who stirred it) made it less orderly (mixed), and time, without the requirement for life, allows it to become more orderly (separated).  I suppose evaporation also tends to make things more orderly, as the residue is then separated out.StuRat (talk) 19:09, 20 March 2016 (UTC)


 * By that reckoning, just about any mechanistic machinery that we have observed, such as the dampening of string vibrations or the eventual dampening down of a playground swing set to its "ground state", or the buildup of layers of sediments, and chemical analogs such as crystallization would also be "counterexamples" forth with that have simply gone unnoticed. No Stu, :), if we are together to ever evolve to the point of a counterexample it will be in spite of it all. It takes considerably more comprehension, observation and ingenuity to arrive at such a point however.. health permitting. --Modocc (talk) 19:48, 20 March 2016 (UTC)


 * My counter-examples are not meant to disprove the 2nd L of T, just show that it doesn't apply at every level. StuRat (talk) 21:28, 20 March 2016 (UTC)
 * Yeah, nice try - but your examples are clearly incorrect. Evaporation decreases the entropy of the material left behind but vastly INCREASES the chaos in the material that evaporates off and gets mixed into the air currents - overall, the entropy of the system increased.  When a string is dampened down, you may argue that it became more 'organized' - but the otherwise calm air around it (that was responsible for the dampening) was stirred up and made more chaotic - and the well organized, constrained elastic energy that was causing the vibration was dissipated as low-grade heat.  The entropy of the string decreased (arguably) - but the resulting motion of the air and the low grade heat that was produced were a massive increase in entropy.  Stirring your coffee imparts a very organized kinetic energy to the liquid - which gradually slows down as a result of turbulence and friction to allow the sediments to settle out.  All of that organized kinetic energy in the liquid's rotation was dissipated as low-grade heat - so, again, entropy increased.  With EVERY example and at EVERY 'level', if you look carefully enough, you'll find that the overall entropy increases...no exceptions whatever.  If you think you found an example where it decreased, then you haven't thought hard enough about ALL of the consequences. 15:24, 23 March 2016 (UTC)SteveBaker (talk)
 * But the 2nd law does apply at every known level (unless you have designed and perhaps operated a perpetual motion machine of the second kind or perhaps considered why relativity is wrong :-)), for the law applies to all known spontaneous processes. --Modocc (talk) 21:40, 20 March 2016 (UTC)


 * Relativity is "wrong", or at least insufficient to explain the universe at all levels, hence the need for quantum mechanics. StuRat (talk) 06:16, 21 March 2016 (UTC)


 * To explain briefly why the statement is wrong: the second law of thermodynamics only applies to closed system -- that is, systems that don't interact with anything outside themselves.  The Earth is not a closed system, because it receives a constant influx of energy from the Sun.  Without some such energy source life (and evolution) would be impossible. Looie496 (talk) 22:47, 19 March 2016 (UTC)


 * Just a general hint: if someone tells you "Evolution isn't true because X", "Evolution violates Y", you can almost always safely assume they are wrong. Science isn't that simple. Fgf10 (talk) 23:13, 19 March 2016 (UTC)
 * Biblical literalists not understanding science? Shazam! ←Baseball Bugs What's up, Doc? carrots→ 23:54, 19 March 2016 (UTC)


 * Exactly. Either the literalists don't have a clue about science, or they do understand it just well enough to think that they understand it and that it supports them.  The second group are more of a problem, because they can be seen incorrectly as scientific.  Robert McClenon (talk) 02:42, 20 March 2016 (UTC)


 * The second law of thermodynamics is the only physical law that isn't time-reversal invariant (aside from the tiny T-symmetry violation in the Standard Model). That means that the second law is implicated in anything that happens in one direction of time and not the other. Evolution is one of those things. The ratchet effect that leads to organisms becoming better adapted to their environment over time (rather than randomly better or worse averaging to no change) is a manifestation of the second law. So it's wrong to say that evolution violates the second law, but also wrong to say (as people sometimes do in response) that it evades the second law (e.g. because the law only applies to closed systems). On the contrary, evolution is an example of the (nonequilibrium) second law in action. -- BenRG (talk) 00:18, 20 March 2016 (UTC)
 * There are interesting things though when Hubble constant and expansion are not time invariant and speed up and slow down. The same process may not yield the same heat or entropy, which strictly speaking is a violation.  Variable rates associated with dark energy and dark matter may very well mess with our understanding of how the entropy of the universe changes and whether we "borrow" or "lend" entropy to other epochs.  --DHeyward (talk) 04:18, 24 March 2016 (UTC)


 * Usually when I hear this come up, they are using an oversimplified statement of the law. I think it applies to a closed system, and the Earth is not a closed system.  See this from the article:

The entropy of the universe tends to a maximum.

This statement is the best-known phrasing of the second law. Because of the looseness of its language, e.g. universe, as well as lack of specific conditions, e.g. open, closed, or isolated, many people take this simple statement to mean that the second law of thermodynamics applies virtually to every subject imaginable. This, of course, is not true; this statement is only a simplified version of a more extended and precise description.
 * Bubba73 You talkin' to me? 00:53, 20 March 2016 (UTC)


 * The second law does apply to virtually every subject imaginable. It's why water flows downhill and not uphill. It's why evolution (a hill climbing process) makes progress up the hill. It's why you remember the past and not the future. It's why the sun shines. Every process that happens more often than its time reversal is that way because of the second law. It's so pervasive that people tend not to recognize that it's there. -- BenRG (talk) 08:58, 20 March 2016 (UTC)

Any statement about the Second Law of Thermodynamics made by anyone other than an academic physicist should be assumed incorrect, absent strong evidence to the contrary. Shock Brigade Harvester Boris (talk) 02:19, 20 March 2016 (UTC)

I will just leave this here... --Guy Macon (talk) 05:32, 20 March 2016 (UTC)


 * Yes, viruses evolve enough each year so that we don't have resistance (and last year's flu shot is made ineffective.) Bubba73 You talkin' to me? 05:40, 20 March 2016 (UTC)


 * With all of these kinds of law, you need to draw a box around a "system" and measure the property inside the system - taking careful account of what enters and exits the system. Choosing the right box can make this either fiendishly difficult or ridiculously easy.


 * I don't know why people find this so difficult - it's no different than any of the conservation laws. How is it that our 3lb puppy grew to an 80lb dog?  Was the law of conservation of mass violated?   Well, no - if we total the amount of puppy chow, water and oxygen consumed and the amount of pee, pooh and CO2 produced, we'd find that there was a continual slight discrepancy between what went into the puppy and what came out - which exactly balances the weight growth of the dog.


 * It's not just evolution that superficially appears to drive entropy backwards - life in general seems to do so even when it's not evolving. But that's an illusion that comes about from picking the wrong box.  A puppy consumes high energy food and poops out low energy waste, along with a lot of low-grade heat.  The entropy of the dog decreases - but at the cost of a much larger increase in entropy of the world around it.  Entropy is at least conserved - and actually increases overall...just as the second law predicts.


 * This also applies to the things lifeforms do. If I decide to spend the afternoon sorting my DVD collection into alphabetical order - then I'm decreasing the entropy of my DVD collection - but in doing so, I consume more calories than if I'd sat in a chair and done nothing.   So in the process, I ate an extra cheese sandwich - and turned more low entropy cheese sandwich into high entropy waste heat to counteract the (marginally) decreased entropy in my DVD collection.


 * We see this everywhere - whenever humans build something (locally decreasing entropy in the process) we trash the planet to a greater degree - increasing entropy all around us.


 * Evolution is just another process that life engages in. In the course of evolving (which we presume to be a largely reverse-entropy process) living things produce more disorganized waste than they otherwise would...so the entire process drives entropy up as the second law predicts.


 * This really isn't difficult.
 * SteveBaker (talk) 14:29, 20 March 2016 (UTC)


 * Life doesn't really increase the order of the universe. Nor does non-life avoid increasing in order locally.  A volcanic eruption, all that heat in one place, crashing steaming into the sea - lots of free energy there.  That doesn't disprove the second law, but just goes to show that so long as you have an energy source of some kind, interesting things keep happening. Wnt (talk) 17:36, 21 March 2016 (UTC)

I thought about this. Crystals form on their own and they are highly ordered. If the anti-evolutionist misinterpretation of the laws of thermodynamics were correct, crystals would not form. But they do - it is a common grade school science experiment to grow crystals. Bubba73 You talkin' to me? 18:52, 21 March 2016 (UTC)


 * Perhaps instead of just thinking about it and then jumping to a conclusion people should read Crystallization? The laws of thermodynamics are probably the most solidly proven laws in all of science.  There are no known exceptions - and if an exception were ever to be demonstrated, it wouldn't be something so well studied as evolution or crystal growth.  Established laws are sometimes (very rarely) overturned - for example when the laws of "conservation of mass" and "conservation of energy" were found to be violated in nuclear fission/fusion and had to be replaced with the law of "conservation of mass/energy".  But this has to happen in areas that are not already well-supported by scientific evidence - generally they require experiments that are out on the extreme edges of what is known.  Crystal formation and evolution are both very well studied - if they somehow violated thermodynamics, we'd know about it for sure and we wouldn't be teaching them as "Laws of Nature" anymore...just as we don't teach "Conservation of mass" anymore. SteveBaker (talk) 19:58, 21 March 2016 (UTC)

Actually I would think the various acceleration/deceleration accounts of the universe are more likely to violate the 2nd law of thermodynamics. I doubt "increasing entropy" is any more golden than Newton's law and we will discover more about why we generally observe increased entropy in everyday life. But dark energy, dark matter, variable rates of expansion and all sorts of cosmological weirdness will simply redefine it. But the second law of thermodynamics regarding life isn't a violation unless the sun is doing something we don't know. It's macro, not micro. Throwing a ball in the air doesn't defy gravity either. --DHeyward (talk) 03:10, 24 March 2016 (UTC)