Wikipedia:Reference desk/Archives/Science/2009 November 20

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November 20

Temperature's Affect on Metabolic Activity

Hello,

I know that as temperature goes up, enzymes become more reactive because substrates move faster and are more likely to bind to the active site. But is temperature proportional to enzymatic activity linearly, quadratically, exponentially, etc? It would help if you can give some kind of justification like a journal article. Thank you. —Preceding unsigned comment added by 69.139.218.4 (talk) 00:30, 20 November 2009 (UTC)

I don't know for sure. But, if the enzyme activity is proportional to the speed of the atoms moving around in the liquid, you can just check how the average velocity of particles is related to temperature. From Maxwell Boltzmann distribution it seems the average speed is proportional to the square root of the temperature. I assume you read Enzyme kinetics, which doesn't cover temperature, but might help anyway. It's possible the speed of the activity of the enzyme itself might change, but I think that it's overwhelmed by variations in when the enzyme comes in contact with the atom, so could be ignored. But it's possible that at low temperature it becomes more important, and at high temperature the atoms move so fast the enzyme has no time to work. So it's probably not a simple relationship over an entire temperature range. Ariel. (talk) 10:30, 20 November 2009 (UTC)

Note that in birds and mammals, attempts to control body temperature may cause us to slow down our metabolic activity when we overheat, so this could figure into it, too. For example, digestion may slow down when we get hot. StuRat (talk) 10:37, 20 November 2009 (UTC)

Your assumption is wrong: Enzymatic activity has no easy and generalizable correlation with temperature. All enzymes have an optimal working temperature, and deviations from this slow reactions down, in general. The exact relationship is different for every single enzyme, and depends an substrate, protein structure and in general the thermodynamics of the reaction catalized. Most human enzymes, for example, would have evolved an optimum around 37°C body temperature (and many start to denature already 10°C above that, so will not be functional any more at this point), but there are enzymes from the archaea which have optimums near the temperature of boiling water, and almost no activity at room temperature. I don't exactly have a journal article for this, but every biochemistry textbook should have a chapter about influence of temperature on enzymes and proteins in general. --TheMaster17 (talk) 10:48, 20 November 2009 (UTC)

The Molecular Basis of the Effect of Temperature on Enzyme Activity. Axl ¤ [Talk] 13:03, 20 November 2009 (UTC)

Technical question about movie cameras used in traditional filmmaking

Does the film used in motion pictures cameras requires film developing? i found the article lack of such specification.

Any help would be kindly appreciated.

If so, which part of the postproduction process is that related. Film editing perhaps?.HappyApple (talk) 02:49, 20 November 2009 (UTC)

Yes. If you look around Kodak's website you will find information about developing motion picture film. --Jc3s5h (talk) 03:02, 20 November 2009 (UTC)

Yes - the film uses the same chemical processes (more or less) as you find in regular still image film cameras. The film stock is generally sent off for processing as quickly as possible after the end of filming each day - LONG before the editing or post-production stages. There is more information in our article: Dailies - the prints that are made immediately after processing to allow directors and producers to see the footage shot on the previous day. These days, they'll use digital cameras mounted alongside the film camera in order to get instant feedback after shooting - but the dailies are still useful to ensure that exposures, color balance and focus were correct. SteveBaker (talk) 03:03, 20 November 2009 (UTC)

Movie cameras for a long time (incl. before the digital era) have had a video tap for similar purposes. 69.228.171.150 (talk) 03:52, 20 November 2009 (UTC)

Thank you for helping me realize where all those clips on YouTube came from! Cuddlyable3 (talk) 11:58, 20 November 2009 (UTC)

Further, most movies include the name of the company that processed the film at the end of the credits. It is not a trivial task. When processing film, it is easy to have one strip of film be slightly more processed than another strip of film. The difference in color on the overprocessed film is very easy to see. If you compare a very old movie to a modern movie, you can see how the picture quality jumped around in old movies but stays steady in new movies. You can also see how experiments to maintain a constant picture quality have progressed through the ages. Most people can recognize a film from the last 60s/early 70s just by the color of the movie. It was a side-effect of the processing of the time. Now, with digital, there is still a need for the people who color balance the films. So, that part of processing isn't going away. It is just done on a computer now instead of with actual film. -- kainaw™ 06:44, 20 November 2009 (UTC)

There was an interesting problem with a batch of film for Lord of the Flies that caused it to get washed out every few seconds, for a few frames. They traced it down to the developer, who was smoking a cigar while developing the film. When he inhaled, the tip of the cigar got brighter and ruined the film. They had to reshoot. StuRat (talk) 10:32, 20 November 2009 (UTC)

Seeing the effort needed to process a single film strip increases one's respect for what was done for the early multi-strip Technicolor versions. Cuddlyable3 (talk) 11:58, 20 November 2009 (UTC)

Thanks for the answers it helped me a lot. --HappyApple (talk) 14:11, 20 November 2009 (UTC)

I dispute the claims of Kainaw and request a reliable source for the claim of poor quality control in film development in past eras. Craftsmen were craftsmen. Edison (talk) 04:59, 21 November 2009 (UTC)

I've seen old silent movies like that, where the brightness varies dramatically. I doubt if it was due to poor craftsmanship, just a lack of automation. If a machine is used to time every step in the development process, you will get more accurate timing than some guy with a stopwatch, especially if he has to go to the bathroom. StuRat (talk) 05:52, 21 November 2009 (UTC)

(To Edison): Have you seen many Buster Keaton movies? How about Birth of a Nation - that's one that most film school students have to sit through. "Color" control isn't the issue in black an white movies, but the color tone shifts from black/white to sepiatone and back. The brightness goes in and out. Consider a scene where it cuts quickly back and forth between two characters, such as the scene where the woman is getting scared of the mulatto in Birth of a Nation. One is clearly more lit than the other. When there was enough money to shoot and reshoot and reshoot, control was better. Still, compare a movie today to a movie from the 60s or 70s. It is very easy to identify the 70s movie. I liked that the recent US series "Life on Mars" purposely imitated the color pallete to make it look like a 70s movie. -- kainaw™ 23:54, 22 November 2009 (UTC)

Static electricity

When you pull a sweater off in the winter and you get sparks between your undershirt and the sweater, what causes that? I know it's static electricity but how does it get there? Dismas|^(talk) 04:08, 20 November 2009 (UTC)

That's called the Triboelectric effect, described in that article and more superficially in our Static electricity article. -- Scray (talk) 04:22, 20 November 2009 (UTC)

Static charges build up easily in dry air, which is typically found in a room with electric heating. Cuddlyable3 (talk) 11:44, 20 November 2009 (UTC)

Lunar water

Hi, the Moon is hotter (I guess) than the hottest desert during most of its daytime. Because of this lunar water is suspected only to exist in those cratered areas near the poles which are in permanent darkness. This makes sense because the water is frazzled and evaporates in the searing month-long heat. What is often claimed is that this evaporated water is then lost to, or flys off into, space. How does the vapor reach exit velocity? i.e. wouldn't it be impossible for vapor to find its way beyond the moons gravitational force without a big push? Does what goes up not come down on La Lune? ~ R.T.G 12:00, 20 November 2009 (UTC)

The moon's scape velocity is small enough that water can reach it simply by random thermal movement. That's why the moon doesn't have an atmosphere. Dauto (talk) 13:03, 20 November 2009 (UTC)

That's true - but it also provides another mechanism for water to get into those always-dark craters. When there are a few molecules of water in the lunar soil, they get repeatedly hit by all sorts of particles and photons of various energies and get thrown out of the soil and up, away from the surface. Some, indeed, gain so much energy that they escape the moon entirely. However, lots of them don't - and eventually float slowly back to the lunar surface - ready to get whacked again. You can envisage this as a bunch of molecules bouncing around the surface of the moon - randomly jumping from place to place...until they just happen to end up inside one of those always-dark craters. Once a molecule happens by random chance to end up in one of those places, it's shielded from all of that incoming energy and there is no way for it to get out. Hence water accumulates in those places - even water that wasn't conveniently deposited there in the body of an icy asteroid impact. There isn't much water in the lunar soil - but when the water from the entire surface of the moon is gradually collected in just a few special places, it can add up to a lot. SteveBaker (talk) 13:59, 20 November 2009 (UTC)

Extending that idea, couldn't other particles (dust) gradually cover (fill-in) the bottom of such craters, such that we could envisage most locations on the moon's surface as having once been the site of a crater? If so, couldn't the buried water be more widely-distributed, and not "in just a few special places"? -- Scray (talk) 14:24, 20 November 2009 (UTC)

No, because water that accumulated anywhere else would evaporate when the Sun heats it up again. Thus it would be kept in motion until it finds a stable position, either in a permanently shaded polar crater or by escaping the Moon entirely. Now for an analogy: Have you ever seen a spot in the center of a road intersection where no cars drive, that accumulates debris ? The debris gets knocked all over the place by the cars, until it finds it's way to that spot, then it stays there. This effect also causes debris to accumulate on the shoulders. StuRat (talk) 17:51, 20 November 2009 (UTC)

To an extent, yes, but dust is much heavier than water (by several orders of magnitude, I think). That means it doesn't move about anywhere near as much. You may find Lunar dust#Moon fountains and electrostatic levitation of interest. --Tango (talk) 14:44, 20 November 2009 (UTC)

It's just hard to imagine natural flow being enough to blow vapour into space. The moon as a low gravity thresh-hold but its not as if you could trip and fly off it not by a long shot. Isn't the upper-Earth atmosphere in a lower gravity state but gas blowing away is only a minor event? Of course vapour collection could be such a minor event too but on the Earth, heat affected gas reacts in conjuction with other gas i.e. is bouyant but on the moon there is little to nothing hosting bouyancy. Would the affected by heat rising off the moon not disipate long before escape velocity and distance and wouldn't our upper atmosphere be blowing away rapidly through the hole over the antartica? Bit vague to answer now sorry but just flaoting away doesn't apply to our familiar surroundings. Thanks for answers ~ R.T.G 16:52, 20 November 2009 (UTC)

The solar wind bombards the planets and moons (especially the inner ones) with high energy particles. This can blow loose those molecules in the upper atmosphere (on those planets and moons lacking a magnetic field which would deflect the solar wind). The gravitational attraction at Earth's stratosphere is only slightly less than on the surface, because it's only slightly farther from the center of the Earth (our atmosphere is very thin relative to the radius of the Earth). However, the lightest molecules still escape (via Jean's escape), such as those of hydrogen. That's one reason why we have hardly any H₂ molecules in the air. Here's a diagram of the Moon's interaction with the solar wind:

      ->   ->_____->    -> ATMOSPHERE BLOWN LOOSE
      ->    /     \ 
SOLAR ->  
WIND  ->   | MOON  |
      ->  
      ->    \_____/
      ->    ->    ->    -> ATMOSPHERE BLOWN LOOSE    StuRat (talk) 17:42, 20 November 2009 (UTC)
  

The process is called Jean's escape and it is one of many processes which can cause a gas particle to reach escape velocity. We have an article on Atmospheric escape. Basically, what happens is that the Maxwell distribution has a long tail - some gas molecules are always statistically going to have much faster velocities; and as those escape orbit, the thermal distribution re-equilibrates. The mechanism of showing that a gas always follows a Maxwell-like distribution is a very complicated derivation of statistical physics and thermodynamics, but it can be done. Nimur (talk) 16:59, 20 November 2009 (UTC)

"First, the water is dissociated into hydrogen and oxygen by ultraviolet light from the Sun, and then the light hydrogen is pulled away in the solar wind."? Maxwell distribution would suggest that water vapour bounces off itself and flys beyond the bow shock region of the moons magnetosphere (no article actually says this and Jeans escape is neither explained or an existing article...) ~ R.T.G 22:21, 20 November 2009 (UTC)

Our article is a bit sub-par. I will work on it over this weekend, and if necessary, create an entire separate article for Jean's escape. Nimur (talk) 08:10, 21 November 2009 (UTC)

That diagram (above) makes it look even more likely that water would accumulate - the 'wind' that is blowing directly downwards at the lunar equator has to either blow around the equator or up or down towards the poles - the velocity of the water molecules as they sweep over the poles would be at right angles to the gravitational vector - resulting in them simply falling into the next available crater that would shelter them from the solar wind. Since the always-in-shadow craters are mostly to be found at, or near to the poles - that would also fit the water-accumulation theory rather nicely. SteveBaker (talk) 23:13, 20 November 2009 (UTC)

Unit conversion

Now, I'm pretty bad with anything mathematical, but it turns out to be quite essential for the work I'm doing with regards to converting units. I've used spectrometry to obtain absorbencies, and I've been given an ε₂₈₀ (constant at 280nm) value to use in the simplified Beer-Lambert law (concentration = absorbency/ε₂₈₀), so I can work out concentration like that.

However, I'm pretty sure that value would give me a concentration in the units of moldm^-3. I need the values in μg cm^-3. I get really confused when trying to convert this values. I can't just multiply or divide the value because it's composed of two parts (the amount, and the volume). How can I convert moles to μg, and dm^-3 to cm^-3 in the same method? Thanks. Regards, --—Cyclonenim | Chat  12:43, 20 November 2009 (UTC)

I don't think I could improve on our article explaining factor-label conversion of units, but if you have a question after looking at that, please ask and we'll try. I found this by first going to the Dimensional analysis page, which is a more standard, but general, term for this type of math. -- Scray (talk) 14:05, 20 November 2009 (UTC)

I'm not sure I know how to apply that technique to this case. The equation I'm using is concentration = absorbency/a constant. If I put in the units, it'll be moldm-3 = one arbitrary value / another arbitrary value. Regards, --—Cyclonenim | Chat  14:50, 20 November 2009 (UTC)

If you have mol/m³ and you want to get to μg/cm³, then you just multiply in a chain, e.g.: (mol/m³)(molar_mass g/mol)(10⁶ μg/g)(10^-2 m/cm)³. Multiplication and division are Associative. -- Scray (talk) 14:59, 20 November 2009 (UTC)

BTW, this sort of math is VERY important in biomedicine - practice it a lot. -- Scray (talk) 15:02, 20 November 2009 (UTC)

I know it's really important, which is why I'm so pissed that I can't understand it! I think I need to work through an example, so I'll provide one and have a go. If C=A/ε, then I can do 0.088/3.65x10^4 and get 2.41x10^-6 moldm^-3, not mol/m³. The problem is that's all I have to work with, I don't have any conversion factors. So to convert moles to mcg, I need to know the molecular mass of BSA. I don't have the molecular mass, sure I could probably find it but something tells me I don't need to. Converting dm-3 to cm-3 is the easy bit because I know how many dm-3 go into cm-3, but I don't know how many moles go into a gram of substance without knowing it's molecular mass. I'm probably missing something, I'm really sorry for me stupidity! Regards, --—Cyclonenim | Chat  15:06, 20 November 2009 (UTC)

If it helps, one of the tables I have actually gives me the volume of BSA in the test tube. For the example above it's 1cm3 of BSA and 4cm3 of H20. It also says the concentration of the BSA stock is 250mcg. Regards, --—Cyclonenim | Chat  15:10, 20 November 2009 (UTC)

This is clear: the conversion from moles to mass is the molar mass, by definition! BTW, I really find it confusing when you write moldm^-3. What's a "moldm"? Yes, I'm pretty sure you mean mol•dm^-3, but I should not have to guess. Ambiguity is the bane of both science and medicine! This is of course meant constructively - best wishes in your studies, -- Scray (talk) 16:25, 20 November 2009 (UTC)

I noticed another point of confusion - you refer to the "volume of BSA". That should bother you a little, since BSA is not a liquid. Therefore, it would not generally be measured by volume, unless the BSA is packed in a reproducible way (like sugar or salt might be, but even then we only measure those by volume in the kitchen). Thus, you're almost certainly talking about a solution of BSA, and the volume would only help (in the problem above) if you knew the concentration of that solution. Of course, if you knew that you wouldn't be using the Beer-Lambert law in the first place. -- Scray (talk) 16:42, 20 November 2009 (UTC)

You're certainly right that I mean mol dm-3, not moldm-3. I guess years of writing it by hand have gradually resulted in me removing the space. My apologies. Regards, --—Cyclonenim | Chat  19:10, 22 November 2009 (UTC)

Thanks for replying, because it caused me to re-read this thread and I'm not convinced I really helped, specifically whether you arrived at a satisfying answer. I probably should have started by stating what you might know already, i.e. that absorbance has arbitrary units (absorbance units or AU) so the constant you're dealing with will have units that look like AU/(mass/vol) or AU•vol/mass. That way, when you divide OD₂₈₀(AU)/ε₂₈₀ (AU•vol/mass) you'll get a quantity in mass/vol. Another link in the logic chain is that one cm³ = one mL. -- Scray (talk) 20:04, 22 November 2009 (UTC)

Whilst I now understand what you're talking about, it turns out that I had the completely wrong idea about what I was doing in the first place. It turns out that now reading pages correctly can be serious business; luckily my course leader has explained it to me just before the submission date. Thanks for your help anyway though, I'm sure it'd come in handy should I need it in the future :) Regards, --—Cyclonenim | Chat  16:39, 23 November 2009 (UTC)

biotechnology - monoclonal antibody

Respected sir.

why not use sendai virus after started to use PEG in monoclonal production —Preceding unsigned comment added by Marimathan kumar (talk • contribs) 12:30, 20 November 2009 (UTC)

Perhaps a more detailed elaboration of what you'd like to know would help. DRosenbach ^{(Talk | Contribs)} 12:46, 20 November 2009 (UTC)

aluminium chloride colorimetry

This is the method to determine total flavonoid content in crude drug. I want to know the principle and limitation of this technique. —Preceding unsigned comment added by 161.200.255.162 (talk) 12:49, 20 November 2009 (UTC)

Did you forget to ask a question? Dauto (talk) 19:39, 20 November 2009 (UTC)

I see a clear question there, even if not phrased in the interrogative mood. (I don't know the answer.) --Trovatore (talk) 22:22, 20 November 2009 (UTC)

Fevers and Calories

I had a fever the other day and it got me thinking. How many extra calories does it take to raise an "average" person's body temperature by 1 deg F (or deg C if you want). I know there's all kinds of factors that go into this question, that's why I asked about average, I'm interested in an answer even if it's close to a guess. Also, what's the survival advantage of a fever due to infection? Does it make the immune system more efficient? or is there another reason? Tobyc75 (talk) 14:39, 20 November 2009 (UTC)

Table 3-4 in this book suggests a 12% increase in caloric need for every 1 degree above 37 centigrade, but I don't think that directly answers your question about how much energy it takes to raise body temperature 1 degree. I suppose a direct answer would be to determine the specific heat capacity of an average human body and multiply by average body mass! For the second part of your question, we have a page for that, which provides a number of hypotheses (difficult to prove)! -- Scray (talk) 14:42, 20 November 2009 (UTC)

For a rough back-of-the-envelope sketch per Scray, the human body can be appropximated as a bag of water of the same mass. Since it takes one kilocalorie (exactly, and confusingly, equal to one food calorie) to raise the temperature of one kilogram of water by one degree Celsius, the actual amount of heat energy absorbed by a 70 kg adult is about 70 kcal (70 food calories) per degree Celsius of temperature increase. As noted, actually maintaining an elevated temperature relative to one's surroundings (mostly against the cooling effects of heat radiated away from the skin and carried away by warm exhaled air) will require continuous input of energy. TenOfAllTrades(talk) 15:51, 20 November 2009 (UTC)

You forgot to mention the ugly part. Nimur (talk) 17:03, 20 November 2009 (UTC)

A fever doesn't just work by burning more calories. It uses the same techniques used to prevent hypothermia (just with the thermostat set a little higher). Constricting blood vessels in the extremities to reduce thermal losses, for example. --Tango (talk) 15:59, 20 November 2009 (UTC)

Creationist evolution

I was thinking and not sure, whether this idea exists, but what is the possibility of evolution, which includes the concept of initial intelligent design (thus supporting the existence of God amid self-going, but artificially prepared evolution)? That is, in order to successfully launch the mechanism of evolution, there should be: first, the original evolutioning species (chicken or the egg, where chicken is supposed to be created by the God); second, favourable conditions for the existence of evolutioning life forms, which fall under the concept of entropy and ultimately under the concept of fine-tuned Universe. In other words, such complex process as evolution could not start spontaneously, without some assistance from the outside. Are there any references to that concept? Brand[t] 18:42, 20 November 2009 (UTC)

Well, there is the concept of the "watchmaker God", who sets everything in motion and then stands back and watches what develops. In some versions of this concept, God actually dies after setting it all in motion. StuRat (talk) 19:04, 20 November 2009 (UTC)

It looks like that. I just would like to expand my concerns above. Given that there are much more hostile, rather than life-supporting systems, I tend to think that the concept of fine-tuned universe is essential to keep the self-going evolution running. Imagine initial life forms, thrown into some hostile environment to evolve. They will rather die instead of evolving. And if evolution takes minimum of several thousand years, someone has to maintain the neccessary conditions. This also points to God. Besides, I am not fully satisified with the evolutionist approach to the chicken or the egg dilemma. If mutation must have taken place at conception or within an egg of chickenish animal, as our article says, then what or who may cause the mutation and why? Most likely, also God. Brand[t] 22:02, 20 November 2009 (UTC)

Not at all. If the first life forms couldn't survived - then they would have died. It took a billion years for life to get started - who knows how many unsuitable lifeforms appeared at random, reproduced a couple of times - then died out. There may have been many, many abiogenesis events before some RNA strand appeared as a result of random chemistry in such a way that it could survive in the environment of the early earth. Evolution doesn't take "a minimum of several thousand years" - that's simply incorrect. You can demonstrate it happening at the level of bacteria in a matter of days. Resistance to a new drug can evolve in a matter of months. Rats that are resistant to Warfarin evolved in a matter of 35 years (Warfarin was first used as a rodent poison in 1948 - Warfarin resistant rats were noted in the 1980's). Early life would have been super-simple - with fast generation times and therefore fast evolution. Human evolution takes thousands of years - but that's because we reproduce over many decades. For something like a bacterium that can reproduce in a matter of minutes - everything can go very fast indeed! The chicken and egg thing - well, mutations are caused by chemicals in the environment, radiation damaging the DNA, copying errors as DNA is copied over and over again...lots of ways. So the mutation causes certainly existed through all of biological time just as they do today. SteveBaker (talk) 02:11, 22 November 2009 (UTC)

That is a very common religious viewpoint. It is, for example, roughly what is believed by most Christians that aren't Creationists (which is a large portion of Christians, probably a majority). --Tango (talk) 22:18, 20 November 2009 (UTC)

Certainly, evolution isn't incompatible with the idea that an intelligent designer kicked off the entire process from the first self-replicating RNA strand - then stepped back and let evolution take over. However, that isn't a way for Christians and Intelligent design nut jobs to get away with it. This hypothetical designer would have no possible way to know how things would turn out. You absolutely can't convincingly argue that the designer set things up from that first DNA strand and with the knowing intention of getting humans out as a result. That's impossible - there are far too many random variations due to quantum theory and chaos theory happening over billions of years for that to be possible. But that doesn't mean that science can support even that most limited view - really, it can't. There is absolutely no evidence that this happened - and in the absence of that evidence, we have to employ Occam's razor and say that this idea is basically untenable. Extraordinary claims require extraordinary evidence - and there isn't any.

In this form, the argument has nothing whatever to do with evolution and everything to do with the concept of 'abiogenesis'. It seems strongly likely that the first self-reproducing 'thing' that evolved by stages to produce all life was simply an astoundingly unlikely-seeming coincidence. However, there has been plenty of time for that coincidence to have happened, given all of the oceans of the world over billions of years...and even if that seems too much of a coincidence, it could have started on some other world and gotten here via panspermia types of mechanisms - which allows for life to have started (by pure luck) in any ocean of any planet surrounding any star in the entire galaxy - or even beyond. When you figure the odds of that happening - it seems like a certainty that life would spontaneously arise without any magical being being involved. Tossing 100 coins and having them all come up heads is very unlikely - but if every cubic foot of water in all of the world were tossing 100 coins once a second for a few billion years...does it still seem so unlikely that they'd never once all show up heads?

SteveBaker (talk) 23:02, 20 November 2009 (UTC)

I disagree with the uncertainty objection. The initial wave function of the world fully determines the future wave function, and it's true that over billions of years it will have branched into a huge number of possible outcomes. But how we interpret that result is basically a philosophical question, and doesn't necessarily have an objectively correct answer. The Many-worlds interpretation would say that all those possible worlds exist. We're experiencing only one of them, but by the Anthropic principle it would have to be one where intelligent life exists. The Copenhagen interpretation would say it's a dice roll like you implied. Hidden variable theories would say that the specific outcome is determined all along even if we can't know it.

The second part I totally agree with. Rckrone (talk) 23:57, 20 November 2009 (UTC)

It may be that on millions of other worlds, conditions were right for a while but due to bad luck life never got started, or others where life did start, but after a while things changed in a way that killed it off. Even in our own backyard, on Mars, there might be evidence that there was once the very early stages of life, but that things didn't work out. Given enough opportunities (and there are billions, possibly infinite) things are bound to go just right and keep going just right long enough for something to happen like what happened on Earth, regardless of how unlikely. Rckrone (talk) 00:10, 21 November 2009 (UTC)

This is the way I understand it, and I think SteveBaker said this, too. We happen to be on a world where things have worked in a particular way, but that set of events did not require an omnipotent and omniscient creator; we just haven't seen all of the versions that turned out differently from ours, on innumerable other worlds of other solar systems of other galaxies. Who knows what our descendents may discover if we give them a chance. -- Scray (talk) 00:51, 21 November 2009 (UTC)

I don't think we should apply the human knowledge to that designer, so he ought to know how things would turn out. It is impossible that the intelligent designer did not what would occur. May be our science just is not advanced enough to fully explain and support creationist ideas, akin to primitive man, unable to explain the lightning? As far as I know, evolution does not answer why the colour range of the life forms represents an established gamma or why the basic pigment of the majority of plants is green. But in terms of fine-tuned Universe you can say for example, that the green color plays a vital aesthetic role as generally accepted placid color. So it is impossible to imagine the majority of plants being brown, yellow, red or of other color. So why from too many random variations we have in particular the green color? Or the blue sky? Brand[t] 11:00, 21 November 2009 (UTC)

Evolution does explain why the basic pigment of the majority of plants is green. That green pigment is chlorophyll, which plants evolved to contain a lot of because chlorophyll does a great job of providing a crucial role in photosynthesis. In turn, there is an evolutionary pressure on us humans to feel more content being surrounded by a lot of green, because the aesthetic appreciation of the color green helps to cause us to settle in nice, green areas, where plant life is thriving, and hence food is more abundant.

Evolution plays a role in why the sky appears blue, too. The sky appears blue because Rayleigh scattering scatters short-wavelength electromagnetic radiation more than long-wavelength electromagnetic radiation, and the shortest wavelengths of electromagnetic radiation that we can see are blue light. Evolution comes into play here in that evolution determined what range of electromagnetic radiation is visible to us. We have evolved to be able to see the range of electomagnetic radiation that we do, because that's the most advantagous range to be able to see, since that's the range of wavelengths for which there is the greatest solar irradiance. See sunlight, and [1]. Red Act (talk) 12:14, 21 November 2009 (UTC)

Just to be perfectly clear, in case there was any confusion: I was in no way suggesting that the mechanism of Rayleigh scattering is in any way affected by human evolution. My point was that the color that the sky appears to be to us is determined by two separate things: Rayleigh scattering, and the range of wavelengths that we have evolved to see. If we hadn't evolved to have "blue" photoreceptors, but still had "green" and "red" photoreceptors, then the sky would appear green to us, since the green wavelengths would then be the strongest wavelengths that we could see. The spectrum that came from the sky would still be the same, it just wouldn't appear the same to us. Red Act (talk) 04:17, 22 November 2009 (UTC)

I'm pretty aware that there are scientific reasons behind that. But the plants were green before the appearance of humans and most likely even before the appearance of herbivores. And how evolution explains the picturesque properties of landscapes? The core question is why evolution has ultimately set not only useful, but also such pleasant parameters? Many self-going processes are negative, like decomposition or aging, while evolution features the increase of beauty among others. How such process defines and shapes beauty in all of its complexity without external assistance or auspices? Brand[t] 13:25, 21 November 2009 (UTC)

Of course plants were green - because their greenness is not caused by a design for beauty, but by functional parameters. Beauty is in the eye of the beholder. It's very much dubious that we have a sense of beauty that is not in some way connected to a utilitarian purpose (select fit mates, select good settlement places, learn to navigate...). And how is decomposition or aging "negative"? What about natural processes like the formation of a snowflake from water? Or a spiral galaxy from gas and dust? Or even the Mandelbrot set from a simple equation? --Stephan Schulz (talk) 13:37, 21 November 2009 (UTC)

Asking why things "evolved to be beautiful" is to completely misunderstand the process. Plants and animals evolved to be the best fit to their environment - and the wind up looking the way they do because that's the best fit to the environment. We find 'natural' things pleasant because we too have evolved to live amongst those things. We evolved to want to live in the kinds of landscapes that we are best suited to coping with - an idyllic landscape is one where we can find food and shelter - we like there to be a lake or a babbling brook in our landscape because we need water to survive. We find poisonous or otherwise unhealthy things ugly - scorpions look incredibly ugly - so do most other harmful insects - the appearance of rotting fruit is abhorrent - the smell of rotting flesh is repugnant. That's because we've evolved to be repulsed by things that we need to avoid in order to thrive. A barren, rocky landscape isn't something we'd generally find "beautiful". Julia sets, Mandelbrot sets (and especially the super new Mandelbulb set) look beautiful because they mimic the real world things that we've evolved to enjoy. The mandelbrot/bulb set would be ignored as a mere mathematical curiosity if it didn't happen to tickle our sense of beauty. (In fact, if you visit the forums where the Mandelbulb was discovered, they consciously rejected many other fractals on grounds of beauty alone). There are a VAST number of other mathematical systems that generate complex fractals - but most of them are ignored because they are considered ugly by our oddly evolved sense of beauty. Even amongst people - we find people beautiful when they show the outwards appearance of health and normality. Any human form that's out of the realms of the common is "ugly" to us because we've evolved to avoid mixing genes that are very different to our own into the next generation. Discoveries such as the uncanny valley really emphasis that. Our perception of color evolved to allow us to distinguish ripe fruit from unripe - our sense of smell to distinguish wholesome from rotting. Beauty is something WE evolved to make us fit into the world that exists - not something that the world evolved to suit us. This mistake is one of the most egregious that the religious and creationist nuts make. SteveBaker (talk) 18:54, 21 November 2009 (UTC)

Ultimately you cannot keep going to a more complex answer (God, gods, etc.) when responding to a question. Natural selection is infinitely simpler than any god one might conjecture. Creationists refuse to answer the question of where their god came from, but I know the answer: we created God. Imagine Reason (talk) 17:49, 21 November 2009 (UTC)

The sky was also blue before humans. If it is evolution, which determined what range of electromagnetic radiation is visible to us, as Red Act says, then the evolution must have anticipated the appearance of humans (which suggests the external intelligent assistance), who, unlike previous life forms, became the first and the only ones to enjoy and appreciate picturesque color values. We have not evolved to be able to see the range of electomagnetic radiation that we do, because even prehistoric men were able to perceive the sky color. As for the natural processes like the formation of a snowflake from water, all or at least many of such things require certain conditions, while the processes like decomposition or aging are self-going, the same way as disorder, which requires much less efforts to take place than the order. And creationists do not need to answer where the God came from because it is simply beyond all available knowledge, but all monotheistic religions actualy refer to one God. Brand[t] 18:35, 21 November 2009 (UTC)

The sky radiates light in a color that we call "blue" because of Rayleigh scattering - a simple physical process that has nothing to do with evolution. We PERCEIVE the sky as "blue" because we've evolved eyes that take best advantage of the available light under a blue sky - and to help us do the things we needed to do while we were doing most of our evolving. That means spotting animals despite their camoflage - detecting what fruit is ripe, what is unripe and what is past it's best. We evolved to see a blue sky - the sky didn't evolve for us to see it...that's just nuts!

Creationists certainly don't need to explain where god came from unless they intend their hypothesis to explain everything. Science has loftier goals - we aren't content to figure out how animals came to be - or how planets formed - we aim to know how absolutely everything began - what makes every smallest thing do what it does. If scientists ever did find evidence for gods - the very next question we'd have would be: "Where did the gods come from?". By failing to ask that question - refusing to even consider it - the Creationists (and especially the Intelligent Designists) cannot lay claim to be scientists...which (sadly) they all too often do. So - what's the answer? Either they have a hypothesis - or they have to seek a hypothesis - or they give up pretending to do science and settle back into their dark ages beliefs while science gets on with the methodical business of sorting out how things actually happened. SteveBaker (talk) 19:23, 21 November 2009 (UTC)

I don't think science does any better than religion at solving the problem of a first cause or infinite regress. At the moment science appears to be blocked off from anything prior to the Big Bang — there is no candidate for anything that would count as observational evidence of what, if anything, occurred before the Big Bang or (more to the point) caused it. But supposing that were to change, it would just push the problem back a little earlier. Either you have an uncaused cause, or else an infinite chain of causes with no ultimate explanation as to why it's there — this is common to all accounts of causality, whether naturalistic or supernaturalistic. --Trovatore (talk) 20:00, 21 November 2009 (UTC)

Steve, evolved how? Was there any evolutionary shift to blue perception, when our ancestors perceived the sky in some different color? As far as I know, the color vision didn't evolve, it just was, which suggests that either the sky was set to appear in pleasant blue to us or our eyes were set to perceive it as blue by intelligent intervention. The colors are a relative term, other life forms perceive them in different ways or don't distinguish at all. Brand[t] 20:36, 21 November 2009 (UTC)

Many animals have different color perception than us. In fact the number that perceive it exactly like we do is small. Most modern primates have tri-chromic vision very similar to ours, but that's rare among mammals. Presumably at some point in early monkey evolution they gained the ability to distinguish colors like we do. APL (talk) 20:56, 21 November 2009 (UTC)

So here proponents of modern evolutionary synthesis run to darwinism... I support the notion above, that evolution isn't incompatible with the idea of an intelligent designer. But it seems like not only he launched the entire process from the first self-replicating RNA strand, but also provides the necessary background since then. The sky example could be just one particular example, unless I misunderstand something. Brand[t] 21:55, 21 November 2009 (UTC)

You absolutely do misunderstand!

Vision has clearly evolved - there can be no doubt that early animals were completely blind - then there was an evolution of light-sensitive patches - then an opening above those patches to provide a measure of directionality - then lenses and irises and all of that stuff to enable a proper image to be formed - and somewhere along that process, light receptors that are sensitive to different frequencies. There are animals at every one of those stages present even in the modern world. I read someplace that there is evidence that 'eyes' evolved many times and in many different ways in different branches of the animal kingdom. Even some kinds of plants can "see" at a primitive level - they turn their leaves to track the sun. People think that dogs (for example) can't see colors - that's not quite true - they see in two colors. We happen to be sensitive to three frequencies - other animals to two frequencies, yet others to just one frequency - or in yet others, there can be sensitivity to as many as half a dozen frequencies. Some animals see ultraviolet (bees, for example) - others in infrared (owls, snakes). Heck, there are even a very rare few humans who can see four frequencies instead of three (See tetrachromat). The point is that each one of those solutions is optimal for the lifestyle of the creature in question. Dogs don't distinguish green from red because - being carnivores - there is no evolutionary advantage to being able to distinguish ripe fruit from unripe. Snakes and owls hunt at night - when being able to see body heat is useful - so they've evolved natural 'night vision' and can see infrared light. Humans are not nocturnal animals - so we never evolved that capability. Bees have really good color vision - and can even see into the ultraviolet because they need to be able to see patterns in the petals of flowers so that they can figure out the precise timing of maximum nectar production. Again - humans don't eat nectar - so we never evolved that capability.

If there was a "designer" he/she/it was pretty useless at the job. Something I read recently: I like the problem of why giraffes can't make much in the way of vocalizations. You might think that it's something to do with the long neck - and it is - but not how you imagine. Our vocal chords evolved from the gills of early fish. In all fish, there is a nerve that goes from the brain to those gills. The nerve on one side of the body goes over a particular artery - the other side goes under it. No big deal for a fish...but as fish evolved to reptile and reptile to small, furry mammals and from there to giraffes - that pair of nerves have continuously evolved to their new functions - at no point in all that time has the nerve on one side of the vocal chords ever changed it's basic route. In humans, the nerve from the brain to one side of our larynx goes directly from the brain - as an intelligent designer would route it. But the nerve that goes from the brain to the other side loops down into our chest cavity - then back up the neck to the other side of the larynx. A pretty poor piece of design - but a not unexpected bit of evolution. Alas, for the poor giraffe - that means that the nerve for one side of the larynx travels about a foot or so from the brain - the other travels all the way down that L-O-N-G neck - around the artery and all the way back again...a round trip of about 15 feet! Hence, the giraffe has an enormous problem - when it decides to go "Whoot!" (or whatever it is they'd like to say) - the message arrives at one side of the larynx WAY after the other - and all that comes out is a kind of pathetic cough.

Why would a "designer" (especially an intelligent one) design giraffes (and humans, for that matter) to have this peculiar problem? There is absolutely no rational reason - it's utterly crazy. However, evolution is blind to the future. In the fish, this was the most efficient way to pack in that nerve - and in each tiny incremental change the benefit to totally rerouting the nerve was insufficient to overcome the tendency for a baby animal to be very, very similar to the parent. Hence at no point in the gradually decreasing ability of giraffes to vocalize was there ever an opportunity to reroute that nerve. Every single fish-descended animal has that exact same wierd connection to the larynx on one side of the body. An intelligent designer with such perfect foresight to produce humans - who evidently intended giraffes to evolve from fishes would have taken the time to route that nerve over the top of the artery in those fish. Only a blind-to-the-future process could make such a colossal error. You'll probably tell me that the designer didn't WANT giraffes to make melodious love calls - OK - but why are all animals with larynx's afflicted with this same gigantic screwup? See: Recurrent laryngeal nerve

Intelligent designer? No - bloody stupid designer! ... Or evolution - only able to make tiny changes at each step along the way. Blind to the future. It's truly the only sane explanation.

SteveBaker (talk) 00:23, 22 November 2009 (UTC)

It sort of boggles the mind (my mind) when people compare religion to science. The two don't address the same field. It is just a misunderstanding. And it is banging one's head against a wall to try to resolve the two, or to point out their differences. Engaging in this matter points out a misunderstanding — probably of both. Bus stop (talk) 00:33, 22 November 2009 (UTC)

Of course they address the same field. They both try and answer questions like "What is the nature of the universe?" and "Why do we observe the things we do?" and "Where did everything come from?". They try and answer those questions in completely different ways, but they are trying to answer the same questions. --Tango (talk) 00:48, 22 November 2009 (UTC)

They do both address the same concerns — in the extremes. At the limits of their respective capabilities they are the same, yes. But most of what they are both about takes place in what can be called more middle ground. The basis of each field of study is mainly the middle ground, where they are both distinct, and it is always an error, in my opinion, to be cognizant of their differences of opinion on any given subject. Science and religion, in my opinion, have nothing to do with one another in the main grounds where they have their most applicability. Bus stop (talk) 01:05, 22 November 2009 (UTC)

Science doesn't have limits - it probes everything - it seeks to explain absolutely everything. You can't hope to retain these religious theories by simply seeking to declare them off-limits to science. If religion truly didn't have anything to do with science - we wouldn't have all of these religious nuts trying to shut down the teaching of evolution in schools...but they do - so there is clearly a large area of overlap. Not just in theory - but in the practicalities of the lives of our children. It's a very real collision of ideas - they simply can't both be true. It's also not just at the fringes. All of modern biology hinges on evolutionary theory - take away that cornerstone and pretty much the whole thing collapses - without evolutionary theory, we can't predict the implications of things like the spread of H1N1 - that's not "in the extremes"! Ditto cosmology - something like 40% of Americans seem to believe that the world is less than 10,000 years old. That can't be stupidity - it can't be lack of information - it's that they subscribe to some crazy religious theory that's 100% at odds with science. This whole "Can't science and religion just co-exist?" is ridiculous. SteveBaker (talk) 01:58, 22 November 2009 (UTC)

Steve, I think the last bit there is crossing the line into soapboxing. Let's stick with scientific answers rather than personal opinions. This is not a forum (for any of the editors in this thread). -- Scray (talk) 02:15, 22 November 2009 (UTC)

Yet you're evidently OK with BusStop's previous comments? That's odd. SteveBaker (talk) 16:59, 22 November 2009 (UTC)

No, I'm not, but I was addressing you at the moment. I think this would be best taken to talk. -- Scray (talk) 17:18, 22 November 2009 (UTC)

This is the science desk. Thinking that science is good is kind of prerequisite for answering questions here, it certainly isn't a personal opinion. --Tango (talk) 02:22, 22 November 2009 (UTC)

Tango, I did not say that support of science is out of place. I referred specifically to Steve's last sentence, which said that the statement "Can't science and religion just co-exist?" is ridiculous. That is a non-neutral point of view about religious belief, and I intended to suggest that soapboxing on that subject is out of place here. -- Scray (talk) 04:46, 22 November 2009 (UTC)

It's perfectly neutral. It is simple fact that science and religion (which we interpret as meaning major religions, there are too many minor ones for me to be able know them all well enough to make entirely general statements) give different answers to the same questions. You can't genuinely support both. You can pick and choose bits from each if you want, but that just gives you an inconsistent view of the world. Of course, people that support science and people that support religion can co-exist, but that isn't usually what people mean - they mean being able to support both. --Tango (talk) 05:04, 22 November 2009 (UTC)

On the topic of whether criticism of religion belongs on the Science desk, I've started a discussion on the Talk page - I suggest we take that topic there. -- Scray (talk) 17:50, 22 November 2009 (UTC)

I guess there's no absolute reason one person can't entertain two intrinsically contradictory world views. Doublethink and all that. Seems like a lot of mental effort, though. I think that it would make my head hurt. APL (talk) 05:52, 22 November 2009 (UTC)

Certainly there are people who try to do this - but it certainly leads to some pretty severe contradictions. When you hold two theories which contradict - it's really not possible to say which activity you should perform in order to achieve a particular outcome. Should I add 10 milligrams of conc. Nitric acid - or should I pray for the right outcome? SteveBaker (talk) 16:55, 22 November 2009 (UTC)

I'm no expert on logic, but I'm sure the tack you've just taken - choosing a ridiculous, tangential example - is unworthy. -- Scray (talk) 17:55, 22 November 2009 (UTC)

It looks to me like Steve is employing reductio ad absurdum, which is a perfectly valid form of logical argument. Red Act (talk) 22:09, 22 November 2009 (UTC)

No, that form of argument requires that the proposition (i.e. belief in religion) leads logically to a conclusion (while handling chemicals, I will pray for a good outcome rather than measuring them scientifically). The fallacy is that the former does not in any way necessitate the latter. If I hold to scientific principles, does that logically lead to my examining my lover's scent with HPLC rather than my nose? Of course not. -- Scray (talk) 23:17, 22 November 2009 (UTC)

(outdent) I think you're misunderstanding Steve's post. I don't think Steve is proposing praying instead of measuring out the nitric acid precisely, I think he's proposing praying instead of bothering to add the nitric acid at all. One of the propositions of many religions is that you can achieve goals just by praying for them. And prayer isn't just a straw man belief, that hardly anybody actually believes in. Every day, many millions of people pray to their chosen mythological figure, asking him to cure their mother's cancer, or let them win the lottery, or make their country's army win the war, or whatever. If prayer actually works, there's no logical reason why it wouldn't also work in the lab. It should sometimes work in the experiment in question to just pray that the metal bits will be dissolved, or whatever it is that you're using the nitric acid for, instead of actually using the nitric acid. Dissolving the metal is something that's easy for even a mere human to do, if they have some nitric acid on hand, so it should be an utterly trivial task, requiring a completely negligible amount of effort, for any deity that regularly gets called upon to perform much more difficult tasks like curing cancer or winning wars, and maybe has even brought some people back to life, or even created a whole universe, depending on the deity involved.

Prayer is generally relegated to objectives that have subjective results, where it's easy to rationalize a negative result as being a positive one ("God wound up deciding that it was mom's time to go to heaven, but at least He gave us a remission for a couple of months so we could spend a little more time with her, and she wasn't in much pain at the end, so that's a blessing, and we should be thankful blah blah blah...) But if you're going to try to mix science and religion, you logically ought to also be able to apply prayer in the realm of science, which involves objectives that have clear-cut, measurable, objective results.

Pure science, however, quite clearly dictates that in the hypothetical experiment, those metal bits are not going to dissolve, unless you add the nitric acid or some other appropriate solvent. So with the starting proposition that both science and religion (specifically prayer) are valid, you reach a conclusion by using the science side of that proposition that whenever you do that experiment, those metal bits will never dissolve unless you add the nitric acid. But you also reach a conclusion by using the religion side of that proposition that sometimes when you do that experiment, occasionally the metal bits will dissolve without adding the nitric acid, if you just pray hard enough for that to happen. That leads to a self-contradiction, which is the final step of the reductio ad absurdum argument. Red Act (talk) 07:25, 23 November 2009 (UTC)

The assumptions you (and Steve) make, including the use of prayer to specific ends, are generalizations. I can understand why you would think of religious people as praying for specific goals, but that's far from universal. Thus, the reductio ad absurdum argument does not hold. While one could react, "well, you need to specify whom we're talking about", I would counter that this is exactly why one shouldn't direct criticism at large, diverse groups of people; you might not even understand them completely. In case it's no longer fresh in your memory, this began a few lines up with a sweeping generalization ('This whole "Can't science and religion just co-exist?" is ridiculous'). BTW, there is a parallel discussion here, and maybe we should move this off RD/S. -- Scray (talk) 11:28, 23 November 2009 (UTC)

Science doesn't have limits - we need to be careful with our terminology. Science, as you mean, doesn't have limits - you mean the general field of study that attempts to explain observations by means of the scientific method. "Science" can also refer to the body of knowledge that has been created by the previous definition, and that certainly has limits. That said, there is one limit to science in the former definition - science doesn't attempt to explain things that can't be observed. If two things always look the same (for an extremely broad definition of "look") then, as far as science is concerned, they are the same. That is a limit, but it is a limit that makes absolutely no difference in the real world (which is precisely why the limit is imposed). --Tango (talk) 02:22, 22 November 2009 (UTC)

And just as science can be misunderstood so too can religion be misunderstood. And just as religion can be abused so too can science be abused. Bus stop (talk) 11:44, 22 November 2009 (UTC)

All true... did you have a point? --Tango (talk) 11:57, 22 November 2009 (UTC)

I don't know. Bus stop (talk) 12:57, 22 November 2009 (UTC)

I'm pretty sure that Astrology, Veganism, Philately, the love of a good woman and driving fast cars can also be misunderstood and abused. It doesn't really prove anything except that people sometimes misunderstand and sometimes abuse pretty much anything. SteveBaker (talk) 16:55, 22 November 2009 (UTC)

I've suddenly found my concern - theistic evolution :) Brand[t] 13:18, 24 November 2009 (UTC)

The Universe

a) How fast in mph is the universe expanding? b) what exactly is it expanding into? c) if it is not expanding into anything then how do we know that the older inner parts of it are not just shrinking and giving the illusion that the outer parts are expanding? d) how old is the universe compared with the age of the earth? I've read its only ten times, which does not seem much. 92.27.157.99 (talk) 19:46, 20 November 2009 (UTC)

d) The Universe is actually younger (or the Earth is even older) than that. The age of the universe is currently estimated at roughly 14 billion years. The age of the Earth, meanwhile, is pegged at about 4.5 billion years — in other words, the Earth has been around about a third as long as the entire Universe. TenOfAllTrades(talk) 20:07, 20 November 2009 (UTC)

b) "If the universe is infinitely big, then the answer is simply that it isn't expanding into anything; instead, what is happening is that every region of the universe, every distance between every pair of galaxies, is being "stretched", but the overall size of the universe was infinitely big to begin with and continues to remain infinitely big as time goes on, so the universe's size doesn't change, and therefore it doesn't expand into anything. If, on the other hand, the universe has a finite size, then it may be legitimate to claim that there is something "outside of the universe" that the universe is expanding into. [...] So the answer in that case is that we really don't know what, if anything, the universe is expanding into." [2]

c) Presumably because the distances are physically getting bigger? - Jarry1250 ^{[Humorous? Discuss.]} 20:57, 20 November 2009 (UTC)

Or your ruler is shrinking without you being aware of it because you are shrinking too. 92.29.18.113 (talk) 21:31, 20 November 2009 (UTC)

That would only apply if all distances increased at the same rate, which they don't. Larger distances increase more than smaller ones. --Tango (talk) 21:35, 20 November 2009 (UTC)

More generally, we can only measure distances by comparing them to other distances. Saying that all distances have increased or decreased across the board doesn't really mean anything. We would have no way to tell. When it's said that galaxies are getting farther apart it can only mean that the distances are getting larger compared to the small distances that we use as measuring standards. Rckrone (talk) 23:05, 20 November 2009 (UTC) Edit: Sorry, didn't see that SteveBaker already addressed this point. Rckrone (talk) 00:54, 21 November 2009 (UTC)

If the universe has finite volume then it is almost certainly still unbounded, that is, it doesn't have a boundary. It might, for example, be the 3D equivalent of (the surface of) a sphere. The Earth's surface is definitely finite, but there is no edge you can fall off. If the Earth inflated like a balloon then we would say it was expanding into outer space, but that's because the surface of the Earth is a 2D space embedded in a 3D space (the universe). While we can think of the universe as being embedded in a larger space it is rarely useful to do so (although see Brane cosmology). --Tango (talk) 21:08, 20 November 2009 (UTC)

a) The universe is expanding at about 70 km/s/mega-parsec (that's the Hubble constant). That is, if two galaxies are X mega-parsecs apart (for large X) they will be receding from each other at about 70X km/s. The farther apart the galaxies are, the faster they recede from each other. --Tango (talk) 21:08, 20 November 2009 (UTC)

c) I don't think we know that the parts close to us aren't shrinking. Surely the two effects are indistinguishable? It is merely convention that we talk about the expansion of the universe - the shrinking of the universe would work also. The idea is that the 'ruler' we're using to compare distances with to is also changing size. All we know is that the ratio between the distance to some distant galaxy and the length of a particular platinum-iridium rod stored in some museum in Paris...is increasing. We can't say that things close to us aren't changing size because the only way to measure them is to compare them to the rod in Paris - and it too could be shrinking. There is absolutely no way to know whether that is because the rod is shrinking or the galaxies are moving further away. However - it really doesn't matter. We can't measure absolute distances - only ratios of distances to standard rulers. However, from a practical perspective - the "big bang" is even harder to get your head around when you think of it that way and the 'inflating balloon' and 'chocolate chip cookie baking' analogies for the expansion get super-difficult to understand when you try to think of them like that...so we stick with the 'expansion' version of the story. SteveBaker (talk) 22:46, 20 November 2009 (UTC)

Ah, yes, of course. We don't use the platinum-iridium rod any more, but I realise that the point holds: most of our units of distance are now intrinsically based on time, and that can change. In the case of a metre, distance covered by light in that fraction of a second can change. Point taken. - Jarry1250 ^{[Humorous? Discuss.]} 09:15, 21 November 2009 (UTC)

Can anyone identify this plant?

Can anyone identify this plant? The photo was taken in Narbonne, in the south of France. Thanks -- Александр Дмитрий (Alexandr Dmitri) (talk) 20:49, 20 November 2009 (UTC)

Looks like Brugmansia to me. Highly poisonous!. Closely related to Datura. --Dr Dima (talk) 22:08, 20 November 2009 (UTC)

The horn-shaped flowers do indeed look like Datura. Previous poster is dead right (sorry), this is a dangerous plant. Don't muck around with it. Myles325a (talk) 00:14, 24 November 2009 (UTC)

Signs of global warming?

Hi. Recently this November, I've noticed numerous signs that may indicate the signal of global warming in my local area. I'm from Southern Ontario. Please address the categories of indications separately.

Animals and plants

• Earthworms - I saw at least three today, after the rain passed by yesterday and last night.
• Dandelions - Yellow flowers, white seed puffs, and flowers in the closing stage. Many sighted within the past week, saw at least half a dozen just three days ago, along with windblown spores.
• Insects - In the past two weeks, I've seen ladybugs, houseflies, and smaller insects that look like mosquitoes.
• Ducks and geese - On one occasion, I saw a number of ducks or geese flying in a near-V shaped formation, and I've also seen many ducks or geese staying in a small pond.
• Seagulls - In the past week, I've seen many seagulls on some days, flocking close to buildings.
• Squirrels - I've seen both the black and the grey squirrels that are common in this area.

Weather

• Temperature - Some nights have been below freezing and frosty, but many have also been above freezing. The autumn chill of the air is missing on some mornings. Four of the next six days are forecast to have nights above freezing. Foggy days have been abundant, and two such days have occured this November. Many afternoons feel very warm with the sunlight and mild temperatures.
• Precipitation - There has only been one snowfall so far this autumn, and the form of precipitation for the previous two days has been rain.

Global

• Sea ice - Arctic sea ice this November has been the lowest on record for this time of year.
• ENSO - A moderate El Nino is developing in the Pacific.

So, do some of these signs, especially those locally relating to animals and signs, suggest that global warming is responsible? Are any of these particularly unusual for my location and time of the year? Thanks. ~AH1^(TCU) 21:54, 20 November 2009 (UTC)

Short term changes in one place are meaningless as evidence for global warming. There are always fluctuations in weather patterns. You need a large amount of data from all over the world over a long timescale to draw any conclusions about the global climate. --Tango (talk) 22:20, 20 November 2009 (UTC)

Indeed. All of these may become more frequent with global warming, but they may also be coincidence. Arctic sea ice is about the most useful single indicator, as it shows some effect of several years worth of temperatures. But even that varies a lot from year to year, and you need to look at long-term trends. --Stephan Schulz (talk) 22:59, 20 November 2009 (UTC)

Good replies so far. For your "animals and plants" category see phenology. El Niño probably isn't affected much by global warming (and any given El Niño certainly isn't a sign of global warming). Short Brigade Harvester Boris (talk) 05:50, 21 November 2009 (UTC)

I recall it being said by some professor on tv that the average global temperature has in fact been getting colder for the past few years. 78.146.30.105 (talk) 18:39, 21 November 2009 (UTC)

Yes, it has. The experts almost all dismiss that as a short term fluctuation, though. --Tango (talk) 20:43, 21 November 2009 (UTC)

See Temperature record if you'd like to see for yourself what the trend looks like. Rckrone (talk) 21:10, 21 November 2009 (UTC)

OK, but what about my observations in plants and animals in particular? Are they unusual? ~AH1^(TCU) 23:52, 21 November 2009 (UTC)

They may well be unusual, and a sign of a late autumn, but that's all: unusual means, after all, not usual! --TammyMoet (talk) 10:22, 22 November 2009 (UTC)

Are plants able to use Creatine to produce ATP?

Are plants able to use Creatine to produce ATP?174.51.21.137 (talk) 23:29, 20 November 2009 (UTC)

I think the simple answer is most likely "no". One study I found (PMID 11878275) enabled tobacco plants to do so by transforming them with the creatine kinase gene. My sense from that, and some other reading (e.g. our creatine article), is that creatine metabolism is a feature of vertebrate animals, not plants, but I'm no plant expert. -- Scray (talk) 01:37, 22 November 2009 (UTC)