Wikipedia:Reference desk/Archives/Science/2011 June 2

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June 2

Help with snake identification, peculiar feature

Hello. So today I was walking out to my boat, and I encountered a snake. I didn't see it at first...I HEARD it. I turned to find a rather large snake (perhaps 1.5-2 meters), brownish/green in color, with a kind of "blurred" diamond pattern (I don't know if "diamond" is a good description, but it had a discernible pattern). Anyway, its head was raised into the striking position, and its tail was erect and shaking vigorously, producing the "rattling" sound. My first instinct (aside from jumping ten feet) was that it was a rattle snake. But when I moved away, the snake slithered of the rocks into the water. It didn't seem very graceful in the water, rather just sort of coiled up and floated, all the while hissing and shaking its tail. It was then, when I could get a good close look at him, that I realized the "rattling" sound had stopped. Despite continuing to shake its tail like a rattle snake, it did not have any visible "rattles." I am very certain of this point. The sound I had heard, I gathered, was from the tail shaking amongst the nearby grass and weeds it was hiding in before going into the water. So, my question is, are there snakes that will mimic the characteristics of a rattle snake as a defense mechanism? Is this common? Any articles you can point me to? Also, do snakes have "nests" that they defend. (This one seemed particularly protective of the area, which is why I think it moved into the water...to get away from us, but still stay near.) And can a snake strike or bite while on top of, and, separately, while swimming underneath the water? (This last part is a question my son had. We didn't see this snake actually swim "underneath" the water, but we have seem some snakes, such as water moccasins, exhibit this sort of aquatic behavior.) I am in the Southeastern U.S. near a large freshwater lake, if it matters. Sorry for the long post. Thanks, Quinn ^{❀ BEAUTIFUL DAY} 04:20, 2 June 2011 (UTC)

Looking at Venomous snake led me to Crotalus adamanteus, the eastern diamondback, which sounds like it could be your snake, as it hangs around in marshes and can swim. It's possible it lost its rattle somewhere along the way but still "rattles" instinctively. Do the pictures in that article look anything like your snake? ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:33, 2 June 2011 (UTC)

As for the rattling stopping when it went in the water, that sounds like what I would expect. The rattle is a series of loose scales that strike one another when shaken. If they have water between them, that would dampen the sound considerably. StuRat (talk) 07:07, 2 June 2011 (UTC)

And, in case it isn't obvious, BACK AWAY FROM THE SNAKE. Our article lists a "mortality rate of 30%" for those bitten, so don't play Russian roulette by hanging around it. StuRat (talk) 07:11, 2 June 2011 (UTC)

There are several harmless snakes that mimic the rattle of a true rattlesnake, among them the corn snake and kingsnakes. As the corn snake article mentions, they're hugely variable in colour and patterning, so it could well have been one of them. While the old saw about telling whether a snake is venomous by the shape of the head is largely bunk, rattlers do tend to have a rather broad flat head in comparison to corns and kings and also tend to have a stockier body, though that will vary more with how successful the hunting has been. Matt Deres (talk) 14:07, 2 June 2011 (UTC)

Wow, yes! I do believe it was a corn snake. Thanks! And upon reflection last night, I wonder if we had "cornered" him against the water, which would explain his aggressive behavior. Quinn ^{❀ BEAUTIFUL DAY} 16:25, 2 June 2011 (UTC)

Many venomous snakes can indeed inject venom on and under the water. Some snakes other than rattlesnakes do shake their tails as a warning. Edison (talk) 04:13, 3 June 2011 (UTC)

List of Tropical cyclone names that were retired after only one use?

What are examples of tropical cyclone names that were retired after just a single use? This includes North Atlantic hurricanes, Western Pacific typhoons, Eastern and Central North Pacific hurricanes, South Pacific and Australian region tropical cyclones, but does not include North Indian Ocean or Southwest Indian Ocean tropical cyclones or cyclones that form between the equator and 10°S and between 141°E and 160°E in the Australian region as their names are retired after a single use anyway (although in the North Indian Ocean once all the names have been used they will create a new list while in the Southwest Indian Ocean a new name list is used every year so they are technically not retirements). Narutolovehinata5 ^tccsdnew 09:19, 2 June 2011 (UTC)

I can't help you with the "one use" part, but you can find an extensive list of retired cyclone names here. Looie496 (talk) 17:38, 2 June 2011 (UTC)

A lot more than I initially thought: Starting in 1954 in the North Atlantic, a new list of names was developed every year, replaced in 1960 by a 4-year cycle. Thus any retired name from 1963 and prior would have been used only once: this list is Hurricane Audrey (1957), Hurricane Connie (1955), Huricane Carla (1961), Hurricane Diane (1955), Hurricane Donna (1960), Hurricane Gracie (1959), Hurricane Hazel (1954), Hurricane Hattie (1961), Hurricane Ione (1955), and Hurricane Janet (1955). I don't have time to look at others, but that should get you started. -RunningOnBrains^(talk) 23:32, 2 June 2011 (UTC)

Escherichia_coli

How serious is to find E. Coli on your salad? (I don't mean the deadly strain, but simply trifle E. Coli). — Preceding unsigned comment added by 80.26.37.77 (talk) 17:22, 2 June 2011 (UTC)

As for the EC alone, there would be nothing to worry about, because you already have a lot in your guts. On the other hand, when you start to wonder on how it might have got there, you cannot exclude that someone or something has dumped on your salad, probably leaving more than just EC there. That's to say, it indicates some hygienic deficits. 95.112.146.231 (talk) 17:51, 2 June 2011 (UTC)

I'm sorry but that's a ridiculous thing to say. E. coli may be fine in your gut, but that in no way indicates that they're fine to chomp down with your salad. E. coli ingestion is a huge concern worldwide (our article mentions 200 million+ cases of diarrhea and 380,000 deaths a year). I don't think it's a stretch at all to say that the strong avoidance normal people have for ingesting shit comes entirely from the fact that people who eat E. coli in quantity have a tendency to get sick and die. Please don't post nonsense of that kind on a reference desk. Matt Deres (talk) 20:05, 2 June 2011 (UTC)

I don't know, maybe we don't eat crap because it tastes like crap. Googlemeister (talk) 20:27, 2 June 2011 (UTC)

No OR please. Matt Deres (talk) 13:24, 3 June 2011 (UTC)

I am sure we have an article on those who are into that sort of thing. Googlemeister (talk) 15:23, 3 June 2011 (UTC)

You wouldn't "find it on your salad" because it's a bacterium and you can't see them without a microscope. There are hundreds if not thousands of varieties of E.coli, most of which could be fatal in the right circumstances. The first you'd know about ingesting it is you'd be sick. I have to disagree with 95.112, though. Yes you do have E.coli in your guts and that's where it should stay. If it gets into the upper digestive tract you will have problems, of which vomiting is but the first sign. --TammyMoet (talk) 18:08, 2 June 2011 (UTC)

This is more about quantity and type than about presence per se. With the exception of a sterilized surgical theater, pretty much every surface in the world contains some quantity of E. coli. Problems arise when you have (a) a lot of it, or (b) a particularly pathogenic strain. Looie496 (talk) 18:23, 2 June 2011 (UTC)

It would be very ironic if OP wrote this before the current outbreak of disease stemming from E. Coli in Germany, which has led to numerous deaths and many people on dialysis machines. Germany blamed Spain, who burned vast quantities of vegetables, only to hear from Germany that the disease came from German hothouses growing bean sprouts. They are understandably very angry. But it does show that bean sprouts can be more dangerous than knuckle of pork, which must have been news to the green vegetarians who are now lying in hospitals. It is also in line with (my notion) that food production will be more and more disposed to infection by increasingly deadly diseases as it moves to hot house and water farm production. This type of concentrated farming is far more amenable to hosting and propagating such diseases, as the vector can hide and spread more easily, just as plagues are more pravelant in cities than they are in villages. Have a look here Myles325a (talk) 08:24, 7 June 2011 (UTC)

Waiter, waiter! What are these things jumping in my salad? These are vitamins. And why are they jumping? This is because they are so healthy! 95.112.146.231 (talk) 18:32, 2 June 2011 (UTC)

The above reminds me of the Australian (and I am one) who was in Paris for the first time and was dining in a swish restaurant there. He called the waiter over: "Garkon, garkon, come over 'ere a sec. There's a fly in soup!" The waiter, dripping Gallic hauteur came over and, looking down his nose, said "But, Monsieur, thet iz vot "Soup de Jour" means. It minz "Fla Soup". The Aussie looked at it closely and then said "Well, how come there's only one of them?"

EHEC

How does the poison get to the kidneys? On my understanding, EC is a normal inhabitant of the intestine and the poison is a protein. Proteins are digested, that's what the bowls are for, and this poses a major problem on the Route of administration for drugs that consist of proteins but should not be digested. If the poison was just excreted into the liquids of the gut, a drastic laxative would do the trick. Some doctors are tight, but not all, so if that would work it would be known by now. 95.112.146.231 (talk) 18:20, 2 June 2011 (UTC)

See Shiga-like toxin. The protein binds to cells in the gut lining specifically (humans, but not cows) and actually mechanically creates little invaginations, which break off inside the cell. Wnt (talk) 19:36, 2 June 2011 (UTC)

With these invaginations (never heard that word before) the toxin (or the whole of the bacteria???) arrives within the cells lining the gut. So how does the story go on? They are not yet inside the blood stream. 95.112.146.231 (talk) 20:01, 2 June 2011 (UTC)

The frequent presence of bloody diarrhea during EHEC infection is a pretty good hint that it is breaking through the bowel barrier in a way that is not typical. Dragons flight (talk) 19:47, 2 June 2011 (UTC)

That thought is exactly mine, this is why I asked that question. 95.112.146.231 (talk) 20:01, 2 June 2011 (UTC)

Well, the toxin doesn't always get to the kidneys - only in about 10% of cases of bloody diarrhea from EHEC (as I've recently added to the article). According to [1] (a site about an interesting drug to stop the damage) the kidneys and intestine both have the same Gb3 glycolipid receptor for the toxin; the kidneys thus are affected if it gets to the bloodstream. I'm at the moment still a bit hazy on how it gets from the affected intestinal cells to the bloodstream, but as we're speaking of dying cells and widespread bleeding it doesn't seem entirely implausible. Ah, sounds like it is transcellular transcytosis: [2] [3] There's even a drug latrunculin B that can increase the amount transcytosed, though I think one to decrease that amount would be more useful! Wnt (talk) 20:52, 2 June 2011 (UTC)

If the toxin is transported inside the cell by Receptor-mediated endocytosis (and for any odd reason not transported on into a lysosome), why shouldn't it be possible to saturate the receptors in question with whatever non-toxic proteins they transport normally? 95.112.137.166 (talk) 11:52, 3 June 2011 (UTC)

Well, the toxin gets in by binding the glycolipid in the cell membrane and physically creating tubules. The link about the drug I linked above talked about saturating the Shiga-like toxin to compete with the glycolipid, rather than the other way around. It's easier to make a harmless high affinity drug that targets the toxin, and there should be less toxin to saturate. Wnt (talk) 03:25, 4 June 2011 (UTC)

Ahem, except actually the other way around does work: [4] ref 4. This paper also suggests that people with Fabry disease may be resistant to the harmful effects of EHEC, perhaps because the Gb3 in other tissues soaks up the virus, so it doesn't all hammer down on just a few tissues. Wnt (talk) 23:32, 4 June 2011 (UTC)

Immune system response to vaccine

When a vaccine is administered and successfully confers resistance, how is the pathogenic material "remembered" by the immune system? I've read Vaccine#Developing_immunity, which doesn't offer any explanation. My understanding is that the vaccine induces production of specific antibodies, but my question is more about the mechanism. Specifically, are different genes being expressed after vaccination? If so, is it fair to say that (some) vaccines trigger epigenetic effects? (I am not seeking any form of medical advice.) SemanticMantis (talk) 18:38, 2 June 2011 (UTC)

As far as I remember, some kind of leukocytes are actively mutating their genes expressing the antibodies. Those with "matching" antibodies are selected to survive. I would greatly appreciate if someone closer to the subject could check if what I memorize is correct and give more details. 95.112.146.231 (talk) 19:02, 2 June 2011 (UTC)

Active_immunity#Immunological_memory is the most detailed article I can find. It doesn't say much about the mechanism of the memory (how the immune system knows which patterns should be remembered). DMacks (talk) 19:09, 2 June 2011 (UTC)

The immune system contains a vast number of B cells which randomly produce different antibodies. Those that recognize "self" are deleted, but those that recognize specific pathogens are expanded exponentially. Vaccines use antigenic parts of viruses in combination with an adjuvant to make something the immune system will respond to by amplifying up the appropriate B cells, but it is still a difficult thing to do, and doesn't always work in every vaccinated person. (I was just reading that flu vaccine only produces immunity 70% of the time...) The B cells do the immune system's "R&D", and when activated they produce a large clone of cells which includes "large-scale manufacturing" called plasma cells; some are also set aside as memory B cells, a sort of "information archive". Wnt (talk) 19:46, 2 June 2011 (UTC)

Thanks, this is how I see it now: after e.g. a successful chicken pox vaccination, the immune system has developed a type of B cell that can make antibodies that will bind to active chicken pox viruses. These antibodies and B cells are novel to that individual, because they were not produced prior to vaccination. Some memory B cells persist, and so are ready to rapidly deploy that antibody should the pathogen be seen again. As for the crux of my question: because the original novel B cells were produced via mutation, it is not appropriate to say this is an epigenetic effect, because the new B cells have novel DNA, not just different expression of the genes that make the antibodies --Is that basically correct? SemanticMantis (talk) 20:07, 2 June 2011 (UTC)

Well, so far as I know is known, the body doesn't really have the ability to respond to a new antigen by mutating the DNA (via V(D)J recombination) in just the right way to make the perfect antibody to match an antigen. Rather, a vast number of B cells already exist with all sorts of different forms of the gene for the variable region of the immunoglobulin. One simply hopes that among all these cells, one can be found which produces an antibody that sticks; this one then gives rise to a vast horde. As a result, while the triumph of this clone can be seen as a special case of natural selection, what is changed is not actually the DNA sequences present but only the number of cells expressing one of them. Wnt (talk) 20:32, 2 June 2011 (UTC)

Immunological long-term memory is believed to be maintained by memory T cells, not by B cells. I'll state that without any specific references, just google "memory cells", and you'll get the point. B-cell memory is short lived in the abscence of antigen. It is true that new B cell clones arise all the time through the random process of V(D)J recombination. Some of these are autoreactive and potentially harmful, some react to pathogens that happen to be around, and are potentially beneficial. However, to get any further, the B cells need confirmation from helper T cells, that it is ok to multiply, and to launch an attack against whatever their antibody is directed at. It is within the T cell population that self-tolerance resides, and it is also there that memory is preserved. After B-cells receive the go-ahead signal from helper T cells, they go through a process of affinity maturation, i.e. somatic mutations of their antigen receptor (=antibody). This is a further genetic alteration of the receptor - after the VDJ rearrangement. Affinity maturation is a feature of B-cells alone, nothing similar happens in T cells. --NorwegianBlue ^talk 20:54, 2 June 2011 (UTC)

I'm not sure how to respond to the idea that memory B cells would die off without antigen - clearly they are maintained in humans for far long. I did omit talking about the role of T cells in the process; however, my impression is that memory T cells are involved in maintaining memory of cell-mediated immunity rather than antibody immunity.

I should also note that what I said before about the lack of directed mutation is starting to show a few cracks: according to [5] a B cell undergoes hypermutation when antigen and CD40 and CD38 ligands are present in the germinal center. They looked at the pattern of mutations, and while there wasn't much to write home about, I think the fact that three different signals converge to trigger mutations would seem to allow for the possibility that something about the antigen or cytokine environment of the infection could hint to the hypermutation machinery about what type or location of mutation would be best. (The authors do not say that - even after all these years Lamarckism suffers a bad reputation. ;) Likewise they didn't actually show stepwise mutation of the B cells to account for the improvement of antibody affinity that occurs during the immune response, but they said they thought they might see it with technical improvements. So the underlying question there I think remains open, though proving directed mutation or evolution in the course of developing the perfect antibody is probably nearly as hard as for nature to implement it. Wnt (talk) 22:38, 2 June 2011 (UTC)

gravity

If the gravitational "constant" changes would this reveal that the force of gravity is growing stronger in proportion to the product of 2 masses divided by the distance between them squared by indicating that the distance between masses is growing smaller or that mass is increasing in value or both? I am asking because the implication of this circumstance is that space is not expanding but that matter is simply increasing in density. Please correct me (after some thought) if you feel my hypothesis is wrong. --DeeperQA (talk) 18:47, 2 June 2011 (UTC)

I'm having difficulty trying to parse your first sentence. I generally overlook simple grammar errors in questions, but in this case I can't figure out what it is that you're intending your first sentence to mean. Could you perhaps rephrase it? Red Act (talk) 19:13, 2 June 2011 (UTC)

Geez... I am having difficulty myself... Sorry for not double checking the grammar after doing some inline editing while posting.. --DeeperQA (talk) 19:28, 2 June 2011 (UTC)

Newton's law of universal gravitation is

$F=G{\frac {m_{1}m_{2}}{r^{2}}}\$,

where:

• F is the force between the masses,
• G is the gravitational constant,
• m₁ is the first mass,
• m₂ is the second mass, and
• r is the distance between the masses.

You observe that the attractive force F can be changed by changing either of the masses or their separation r. The only way to show which of these has changed is by measuring it separately. The value of G can be measured and is as far as we know a constant. Over 200 years ago the first measurement of G found a value within 1% of today's value. Have you read the article Gravitation which notes present theories about gravity? Cuddlyable3 (talk) 19:20, 2 June 2011 (UTC)

Not recently but I will read it again... The time scale here I have in mind would be in billions of years rather than only 200 but I guess we are stuck with only that... --DeeperQA (talk) 19:33, 2 June 2011 (UTC)

I think the OP is curious about the difference between:

• changing the value of G, the gravitational constant - which would indicate that the "rules of physics" are changing (since G is a fundamental physical constant); as opposed to
• changing the units by scaling the way we measure mass, relative to force - see Natural units to understand why this is not an issue. It doesn't matter if we change units; the relevant, empirically observed laws of physics will still be valid.

This stuff can be a little bit mind-bending, so read the natural units article a few times if you lose your way through there. Nimur (talk) 21:02, 2 June 2011 (UTC)

Thanks for you comment. My actual interest is in whether space is expanding and if not what the alternative explanation might be of distance between centers of mass (Black Holes) might really be. While the decreasing size of a Galaxie is perhaps explainable by increased density due to a change in the gravitational constant (making it a variable rather than a constant) this does not explain the increasing distance between the centers of mass themselves. On the other hand if the gravitational "constant" is changing in the opposite direction then this would explain both increasing distance between centers of mass and perhaps an increase distance between centers of mass and objects surrounding them.

Bottom line is that the earliest possible time we could have enough data to make a determination as to whether the gravitational constant were variable is around the last strike of the clock known as the Long Now in absence of supercomputer simulation. --DeeperQA (talk) 17:21, 3 June 2011 (UTC)

Diamonds

How do they tell between a diamond that is naturally mined (and cleaned and cut) and one that is made in a laboratory? (the latter with the intent of making jewellery/resembling a natural diamond, of course) They are chemically identical, aren't they? 72.128.95.0 (talk) 19:47, 2 June 2011 (UTC)

In the past I've read that the synthetic manufacturers were pressured into adding ultraviolet dyes or other markings to avoid angering the cartel. I don't know if that's still the case. Also Synthetic diamond mentions that laser-inscribed serial numbers have now become widespread on the mined stones. Wnt (talk) 19:49, 2 June 2011 (UTC)

An indication (though not conclusive) is that synthetic diamonds are more likely to be free of impurities and flaws, but once you get cleaned and cut, then this distinction is less obvious. Googlemeister (talk) 20:15, 2 June 2011 (UTC)

Of course, they could also add impurities and flaws to the synthetic diamonds, to better mimic mined diamonds. I have to think it's just a matter of time until diamond prices collapse, when lab diamonds flood the market. StuRat (talk) 20:43, 2 June 2011 (UTC)

Sigh. I've been thinking the same thing myself, for at least 20 years. But the nature of wealth is not tangible or sensible; it is a mass hallucination. The difference between a 100 million dollar painting and a worthless beginner's fumble, the difference between a Hollywood diva and a dangerous homeless man with a criminal record on the street, a $100,000 dress and a bargain rack purchase, a million dollar webpage and a worthless scrap of spam - all imaginary. Humanity is mad, and it savages its "poor" based on pure delusion. Wnt (talk) 22:44, 2 June 2011 (UTC)

[6] [7]. Nowadays natural (mentioned in Synthetic diamond) and I think most synthetic diamonds sold for the jewelry market tend to have serial numbers. And the Kimberley Process Certification Scheme even if it's perhaps not to successful at stopping conflict diamonds probably helps stop large quantities of synthetic diamonds winding up as natural ones. Nil Einne (talk) 04:02, 3 June 2011 (UTC)

Asking myself: "Why would that be of any interest?", I guess (but might be wrong) that you are concerned about US-debts and/or Euro-crises but don't want to invest into Rubels or Renmimbi Yuan because of the political dependence of these currencies, nor into already overrun "small market" currencies as the Swiss franc or the Norwegian krone, nor into natural resources based currencies like the Canadian or Australian dollar (prone to collapse on the economic slide to follow the financial crash) and you clearly see that gold is already dangerously high priced. If so, please ask yourself: who would re-buy diamonds, artificial or not, if the global currency system would break down? If I had the money, I would invest into an electricity generator with a sterling motor, some packs of dried rice (which I already have) and some extra tins of food (accumulating). 95.112.146.231 (talk) 20:37, 2 June 2011 (UTC)

And the guy next door could invest in a shotgun and some ammunition, and thus get both his shotgun as well as a generator, a sterling motor, and some food. Googlemeister (talk) 20:48, 2 June 2011 (UTC)

Why did you have to give me away? And I would have got on the liver, too. 95.112.146.231 (talk) 21:05, 2 June 2011 (UTC)

To 95.112.146.231: your generator would be useless if the market collapses because you won't be able to buy gas for it, whereas my precious diamonds and gold will still appeal to the woman, and that's more important than the food. – b_jonas 15:20, 5 June 2011 (UTC)

see stirling motor can run on sunlightIdreamofJeanie (talk) 13:39, 6 June 2011 (UTC)

Cutting a moving object in half

Hello.

Let's imagine we have a 100 kg rock hurtling through a vacuum with an kinetic energy X. Suddenly, a high-power laser appears and dissects the rock into two different parts. Both parts are exactly the same size (volume) but, due to density differences, part 1 carries 60% of the weight of the original rock and part 2 carries only 40%.

How will the original kinetic energy X of the primordial rock be distributed? Will the two child rocks receive 50% each, or will they receive 60% and 40% respectively? I.e., will the kinetic energy be redistributed according to mass or to volume, or otherwise?

Thanks in advance. Leptictidium (mt) 20:02, 2 June 2011 (UTC)

Let me ask you this, where in the equation that calculates kinetic energy does volume fit? Googlemeister (talk) 20:13, 2 June 2011 (UTC)

Kinetic energy is proportional to mass. Unless the cutting-process causes different parts of the mass to exit with different velocities, (i.e., an "inelastic collision with a laser beam"), then the kinetic energy does not change; and each sub-element's kinetic energy can be calculated as always, $E_{k}\approx 1/2m_{i}v_{i}^{2}$, for the i`th particle. Nimur (talk) 20:21, 2 June 2011 (UTC)

This question is reminiscent of a statement I heard from BION an executive in a major satellite communications company. He maintained that the orbiting height of a satellite depends on its weight. I asked him to consider a satellite in stable orbit that suddenly breaks into two unequal parts. Do the two parts move apart and take up orbits at different heights? Cuddlyable3 (talk) 21:33, 2 June 2011 (UTC)

Very likely, yes: the two halves of the satellite are almost certain to have centers of gravity that differ from the CG of the satellite as a whole, which will put them in (slightly) different orbits than the original satellite: one further out than the original, and one further in. --Carnildo (talk) 01:40, 4 June 2011 (UTC)

About divding any moving object to two unequal pieces - mass is dividing two pieces, the first momentum will divided equal, then the velocity will differ wise, and the light piece will have further velocity, then its difference of first velocity, (V2-V1)x(V2-V1) will be further, and little one will have further kinetic energy.

A. Mohammadzade — Preceding unsigned comment added by 81.12.40.120 (talk) 07:27, 3 June 2011 (UTC)

Generally, it will depend on mass difference and first velocity. May it be (M-m) further than square(V2-V1). --81.12.40.120 (talk) 07:35, 3 June 2011 (UTC)

Excuse me, my page has difficulty and problem for better editing or blockout. --81.12.40.120 (talk) 07:39, 3 June 2011 (UTC)

No, momentum will be divided in proportion to the masses (not volumes), and velocities will remain equal unless there is some explosive force between the fragments, so kinetic energy will be proportional to mass, as explained above. Dbfirs 22:29, 3 June 2011 (UTC)

Please forgive me my second reference on the same day to Jules Verne novels from this desk. Off on a Comet, book 2 chapter 17 talks about such a situation. (Well, the rock is a bit heavier and is split by seismic activity instead of a laser.) – b_jonas 15:11, 5 June 2011 (UTC)

we can suppose two masses move together in same velocity in global dependend system (M&m). So the remnant momentom law sayes MV1=mV2 then V2/V1=M/m......(V2-V1)/V1=(M-m)/m--78.38.28.3 (talk) 03:13, 7 June 2011 (UTC)

how much butter

How much butter a day could a farmer in the 1870s US have made from 1 cow? I assume that there is a pretty decent range based on cow breed, and there would be a day to day varaince, but I am just looking for a ballpark estimate. Googlemeister (talk) 20:30, 2 June 2011 (UTC)

According to Dairy cattle, "production below 12 to 15 liters of milk per day is not economically viable", and according to this site (linked from Churning (butter)), "it takes 21 pounds of fresh, wholesome cow’s milk to make each pound of butter." So, 12 litres is about 25 pounds of milk, and thus will produce about 19 oz of butter. Tevildo (talk) 23:55, 2 June 2011 (UTC)

But only if the milk is "wholesome." I wonder in what scientific units "wholesomness" is measured :-) . {The poster formerly known as 87.81.230.195} 90.201.110.199 (talk) 08:04, 3 June 2011 (UTC)

Cells / ml, as it happens. Tevildo (talk) 09:55, 3 June 2011 (UTC)

Yield will be much different historically. Texas lists the average going from 2,940 lbs per cow per year in 1928 to 20,900 in 2009.[8] About a seven-fold increase and we still need data from 60-years earlier. 75.41.110.200 (talk) 14:22, 3 June 2011 (UTC)

The definition of economically viable would be very different too I presume, especially for a farm where dairy output is for internal consumption rather then sale. Googlemeister (talk) 15:21, 3 June 2011 (UTC)

The statement concerning economic viability in our Dairy cattle article refers to current conditions and has no implications for conditions in the 1870s. For example, modern dairies mostly use Holstein cattle, but a farm in the 1870s would have been more likely to use a different breed, such as Jerseys, which produce a high quality of milk, or Guernseys, which tend to be gentle cows easy to work with. The Texas data linked above is probably a better guide. Note that it shows an average of about 3000 pounds per year until about the middle of the 20th century, when per-cow productivity began a rise that continues today. Using Tevido's link, that implies something like 143 pounds of butter per year. Note that this does not mean 143/365 pounds per day. Cows produce milk only some of the time, and when they do produce milk the amount varies. So 19 ounces of butter is probably not out of the question in the 1870s, but that would have been a very good day, or a cow that (at that time) produced an unusually large amount of milk. John M Baker (talk) 18:41, 3 June 2011 (UTC)

You can not make butter from cows. μηδείς (talk) 01:20, 4 June 2011 (UTC)

ROFL! AndyTheGrump (talk) 01:52, 4 June 2011 (UTC)

Butter was sometimes diluted with tallow by unscrupulous farmers and merchants, so you could make some "butter" from a cow, loosely speaking.Edison (talk) 20:50, 4 June 2011 (UTC)

Fractal antenna for TV ?

The log-periodic antenna has existed for decades, but are any other fractal designs in use for TV reception ? If so, how do they compare, performance-wise, with other types ? In particular, I'd like an omni-directional TV antenna (or perhaps a bi-directional antenna with two wide lobes, so that two such antennae would give me full coverage). StuRat (talk) 21:09, 2 June 2011 (UTC)

An omni-directional antenna cannot discriminate between signal in line-of-sight from the transmitter and reflected signals that show as Ghosting (television). A directional antenna has gain in the preferred direction, which is needed to receive weak signals and reject interference arriving from other directions. Antenna gain (see article) is the main performance measure of an antenna and for the VHF and UHF frequencies used for TV the basic Yagi-Uda antenna wins on gain per weight of metal and on simplicity. Cuddlyable3 (talk) 21:23, 2 June 2011 (UTC)

The easiest, simplest, most "populistic" way to prove to a person the earth is older than 6000 years old?

thanks. 109.67.42.106 (talk) 22:39, 2 June 2011 (UTC)

Varves. Even an idiot can understand them, and the varves in the Green River Formation are 6 million layers, i.e. 6 million years, deep. Red Act (talk) 22:50, 2 June 2011 (UTC)

Varves are good, as are ice layers. Dendrochronology is as well. I tend to stay clear of fossils because most people don't really understand the topics well enough to be convinced -- biology (bone physiology), chemistry (radioisotopes) or physics (etc.). DRosenbach ^{(Talk | Contribs)} 13:09, 3 June 2011 (UTC)

Dinosaurs. - DSachan (talk) 23:08, 2 June 2011 (UTC)

• Hmmm, I though that God created the Earth with varves, Dinosaur fossiles etc. 6000 years ago :) . That's why I accept that I can't prove that the Earth isn't 6000 years old, but I then also say that they can't prove that the Earth wasn't created 5 minutes ago. Count Iblis (talk) 23:09, 2 June 2011 (UTC)
• I'd opt for Dendrochronology. We have about 11000 years of fully anchored series of tree rings. And they match the radiocarbon date. That said, science does not provide absolute proof, and it's very hard to convince people that have non-scientific reasons for believing 6000 years. After all, god can grow two tree rings per day, or a varve every minute, if she exists. --Stephan Schulz (talk) 23:11, 2 June 2011 (UTC)

(edit conflict)Fossil fuels need millions (or at the very least hundreds of thousands) of years to form. However, I feel any explanation simple enough to be understood by someone who believes in Young Earth Creationism is going to fall victim to the "God put it there" argument. If someone doesn't believe in science you can't use scientific arguments on them. Really, the best you can hope to do is just stick to patience and explaining how everything we use every day, from phones to cars to computers to the foods that we buy, would not be possible if science was wrong; and science and Young Earth Creationism can't both be right. -RunningOnBrains^(talk) 23:12, 2 June 2011 (UTC)

Looking at all the chaos in my room, I can't believe (now that I'm sober) that I should have done that. So the only explanation to me is that the world as such was created no longer than 20 hours ago and what I see are the remnants of primordial chaos. To be more serious: if someone believes in some almighty force that can make us believe anything, any reasoning is void. 95.112.146.231 (talk) 23:23, 2 June 2011 (UTC)

Following on from what others have said, you might be on more productive ground trying to convince them that the Bible isn't literally true (which will be the main basis for their belief). The difference between Genesis 1 (where the sequence is plants (Gen 1:11), land animals (Gen 1:25) and humans (male and female - Gen 1:27)), and Genesis 2 (where the sequence is Adam (Gen 2:7), plants (Gen 2:9), land animals (Gen 2:19) and Eve (Gen 2:22)) is a useful start. Tevildo (talk) 23:41, 2 June 2011 (UTC)

Once upon a time I met someone who asserted that the Bible was "literally true" and then went on to explain how it was all "entirely consistent" with science, e.g. he accepted old earth, radiocarbon dating, and everything. Sadly, I don't remember the interpretation he was using. However, by starting from the position that the Bible is "true" he had rather more success getting skeptics to listen to him and think critically about his arguments than someone might have had if they approached it from a purely scientific angle. Dragons flight (talk) 23:58, 2 June 2011 (UTC)

If someone reconciled the Bible to science, then they can't take it as being literally true (i.e., creation in 6 x 24 hour days). AFAIK reconciling requires taking the Bible metaphorically in order to line up Creation to what science tells us of the Earth and the universe. PЄTЄRS J V ►TALK 00:30, 3 June 2011 (UTC)

I admit that it seems contradictory to believe in both a "literally true" Bible and in science, but that is how he described his beliefs to other people, and it seemed to be rather effective to discuss it that way. Dragons flight (talk) 01:13, 3 June 2011 (UTC)

Old Earth creationism. For example nowhere does it say that a 'day' was 24 hrs/86400 seconds while god was doing the creating, so make that little terminological twist and you've got as much time to play with as you like. If you believe hard enough, you can make any fact fit your beliefs. --jjron (talk) 14:19, 3 June 2011 (UTC)

Africa and South America look like they fit together (even children notice this), and they are moving apart at a rate of 2.5 cm / yr. They are approximately 5000 km apart today so it would take about 200 million years to get that way. (The actual separation occurred 120 million years ago, so it isn't a terrible estimate.) Of course, like most arguments for an old earth, one can invoke any number of supernatural explanations to counter this, but if someone is actually open-minded (rather than simply dogmatic) then they might realize that all the special pleadings sound silly after a while. Dragons flight (talk) 23:47, 2 June 2011 (UTC)

Kuhn taught us that the paradigm of science is also dogma. Dont forget it. — Preceding unsigned comment added by 129.67.39.207 (talk) 23:52, 2 June 2011 (UTC)

Absolutely anything you claim is easily countered with "God made it look like that when he created Earth." The only way to counter that argument is the assertion that God is not capable of creating a planet that is older than 6,000 years. Then, the other person is left either agreeing that God is not all-mighty or that it is possible for the Earth to be older than 6,000 years. Similarly, you can claim that it is impossible for God to created a Bible that is not literally true. That forces the other person to argue that God is capable of creating a Bible that is not literally true. As with just about anything, the strength of the creationist/young Earth argument is that God is all-mighty. That is also the weakness of that argument. -- kainaw™ 01:02, 3 June 2011 (UTC)

I like to conduct the thought experiment of imagining a child who was exposed to no religion while growing up, but only given the best scientific explanations for everything, along with the the fact that science is always seeking better explanations of everything. Would that child invent religion for themselves? HiLo48 (talk) 01:06, 3 June 2011 (UTC)

The Emperor Commodus will always be the definitive counter-example to any thesis that education (alone) can produce morally admirable behaviour. Whether atheism is morally admirable is another point altogether. :) Tevildo (talk) 01:24, 3 June 2011 (UTC)

The age of the Earth is not necessarily linked to the age of the rest of the universe, but some grasp of the age of the universe might challenge the thinking of a person contemplating signing-up to the 6000 year-old model. Astronomers have decided the nearest large galaxy cluster, the Virgo Cluster, is about 59 million light-years away. See Light-year#Distances in light-years. That means the light from the Virgo Cluster that can currently be observed on Earth started its journey 59 million years ago. However, be aware that the creation scientists are likely to respond to this by postulating that the speed of light is much slower than it used to be in the good old days before there was so much sin about. Dolphin (t) 01:32, 3 June 2011 (UTC)

I would just note that the "God put it there to fool us" argument assumes a God who would willfully deceive us in a terribly contrived way. There is really no evidence for such a God in the Bible — the God of the OT and NT certainly does a lot of strange things, but elaborate practical jokes on all of humanity aren't among them. The closest analog I can think of is Job, but that was sort of a one-off case of God being a huge jerk just to see what would happen. --Mr.98 (talk) 01:34, 3 June 2011 (UTC)

A similar discussion occurred at Wikipedia:Reference_desk/Archives/Science/2010 August 21#Noah's Ark. I find it appealing to consider (as a model) that there might be two orthogonal dimensions of time, namely time as we experience it, in which the events of the universe play out over time with apparent causality, and time as God experiences it, in which whole universes can be seen as sculptures in spacetime, and one is replaced by another and another. Thus the first day, in the divine dimension of time, sees the creation of a whole universe that lives and dies as shades of light, and the fourth one where plants but not animals are permitted by the laws of physics. These universes might either be considered as standalone sculptures, or as a sort of continuum in the second temporal dimension. Ideas about the waters of Lethe, for example, can be rephrased in the sense that one universe in which bad things happened will be replaced by another where they cannot.

Now of course none of this is proof, but the point is, there is room in the scientific philosophy to allow for a God who is truly omnipotent. There is no need to reconcile the biblical notes on the book jacket about the writing of the story with the actual plot of the story of this universe itself. We can all get along.

Last but not least we should note that some models, which pixelize space or otherwise suggest that there is a finite amount of information in the universe, mean that the entire universe at a moment can be expressed as a single (long!) rational number, which expresses everything that is to be known about it. The laws of physics as we experience them are just one particular mathematical series of these numbers, which progresses according to some set of rules to create - somehow - a sense of a temporal series of events that we can experience. But everything that could possibly exist, could possibly be seen or felt or heard within our laws of physics, exists as other numbers. And there could be other physical laws, other mathematical series, which link those together into other possible narratives. The question of what is real, what is miraculous - it goes deeper into philosophy than I can fathom. There is room for anything of any size there, even God. Wnt (talk) 01:53, 3 June 2011 (UTC)

There are plenty of scientists who are creationists. Not the most eminent scientifically, but an interesting one because he writes about creation as a scientist, is Nathan Aviezer. --Dweller (talk) 13:19, 3 June 2011 (UTC)

I'll cite again here, what a friend who is both a scientist and a Christian, has to say about this: (1) God does not deceive; and (2) Evolution is how God works. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:04, 3 June 2011 (UTC)

But if that's the Christian God, he has allowed the creation of the Bible, which describes something very different from evolution as the model for creation. Isn't that being deceptive? HiLo48 (talk) 19:02, 3 June 2011 (UTC)

God gave us free will. Don't blame God for what humans choose to do. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:04, 3 June 2011 (UTC)

Evolution gave us both inquisitiveness and imagination. The need to provide explanations led man to imagine God. Delusions of God leads some people to discount evolution. Therefore evolution is deceptive.  ;-) Dragons flight (talk) 19:16, 3 June 2011 (UTC)

Which is still consistent with "God putting it there". If I were God, I could have used the laws of physics to create the universe 13.7 billion years after the big bang, instead of right at the big bang. The two universes are related by a time evolution operator, so there is no a priori scientific reason to believe that if one scenario is possible, the other isn't. So, if you believe in creation in the Biblical sense, you can just as well believe that God created the universe 5 minutes ago. From a theological POV, the latter possiblity is better, because terrible things like WWII wouldn't really have happened, so it would address the criticism that God let terrible things happen. Count Iblis (talk) 16:48, 3 June 2011 (UTC)

Here we get into fine details of omnipotence and scientific knowledge. Consider for example the classic Torah story was that God can create anything there is, and quickly, but not instantly, and not without effort. There were days of labor involved. Now if you assume this is true for a moment, and that God created the laws of physics and the phenomenon of evolution, then it implies there was a time before the cosmological constant or the idea of natural selection existed. We do not see such a time by natural science, not even if we go all the way back to the Big Bang - and that's a sort of temporal singularity that rules out our asking what happened before it. We can't, of course, because natural science must assume that the same set of natural laws always applied; our past is a deduction according to them. But they do not rule out some other sense of time that works differently. Wnt (talk) 17:28, 3 June 2011 (UTC)

The Deistic philosophy would be that God started the process rolling and then sat back and watched. If there's anything God has plenty of, it's time. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:29, 3 June 2011 (UTC)

(ec) Alternatively (or equivalently?), if one takes the view that God is "outside of time", as a number of theologians have done, including C.S. Lewis, Thomas Aquinas, Augustine of Hippo..., so "time exists only within the created universe, so that God exists outside time; for God there is no past or future, but only an eternal present" as our article puts it, it is not clear that this distinction is meaningful; because on this view God created the entire universe, its entire past, entire present, and entire future, all in one go, in a single act, in a single instant. For such a universe there isn't really a distinction between a universe created 14 billion years ago; or a universe created 6000 years ago with a 14 billion year history; or a universe created in the 6 billion years in the future with a 20 billion year history that our present experiences are part of. If past, present and future are all created at once, then all these descriptions are equivalent.

More to the point, if God created a universe 6000 years ago, and thought it was worth giving it a fully-formed consistent 14 billion year history to, what kind of lazy good-for-nothing followers do they think they are, to decide they can't be bothered to be interested in what has been created for them? Jheald (talk) 17:53, 3 June 2011 (UTC)

As for another way of getting him to emotionally bridge the idea that there might be more than 6000 years of reliable history, I wonder whether talking about Y-chromosome mutations and how they can be used to work out family trees could be helpful? -- ie how, if you start say from say an original emigrant to America in the 1600s, the branches of the family tree separate, mutations occur on particular branches, and get passed down, so that now if you start with a big group you can look at who has which mutations and who doesn't, and use that to put the entire branching family tree back together. My feeling is that this might work as a way in because it relates to something very everyday and immediate and practical and useful -- working out one's family tree; and one can concretely look at such branching trees discovered for real family studies that have been done. But of course once that is accepted, it's not such a step to say: but of course we can do that for the whole of mankind, and fit them all into such a tree - which one can concretely show, and the mutations all hierarchically stack in beautifully ... only it must have taken more like 6000 generations to happen, than 6000 years. But then of course you're only a hop away from saying you can apply very very similar genetic techiques to species, with some examples, and they too fall into a hierarchical family tree of mutations. Though I guess that might take you beyond the "I don't want to know that" threshold. Jheald (talk) 18:54, 3 June 2011 (UTC)

There is no point in trying to prove that the world is older than 6000 years. The person you are addressing will either have bothered to learn the science or won't. The real question is, what kind of sick, malevolent, all-powerful being would create false evidence to convince those who use reason and their senses that the universe is 13,000,000,000 years old if it weren't? μηδείς (talk) 01:25, 4 June 2011 (UTC)

To Medeis: sure, no point.

Why would religious traditions, stories, visions, and inspirations disagree with our knowledge of the physical world? Well, for one thing, if they didn't, they'd merely be scientific treatises. But more fundamentally, religion serves the useful purpose of fouling up the plans of those who have too much simple order in mind for the human race. It's like Frank Herbert's "Bureau of Sabotage" in Whipping Star, which prevents bureaucracies from working too efficiently. There's always someone who has to bring his little ceremonial dagger on the airplane, who demands to be photographed only while wearing a chador, or perhaps not at all, who won't swear on the Bible because the Bible says not to, who won't take the Pledge of Allegiance because his allegiance is to another, who will march into the clubs of the police singing that they won't be moved (or stopped, for that matter). The beauty and truth of religion comes not from what it proves, how it is deduced, but from what it is, its simple essence, as people choosing to be people. Wnt (talk) 05:50, 6 June 2011 (UTC)

Oh, to get back to the OP's question, I think that "continental drift" (just the observed separation of the New and Old World, without getting into the details of plate tectonics) is a good thing to use. We can measure the rate of the continents' separation in centimeters yearly; we can show data that there's a midocean ridge in the middle of the Atlantic, with symmetrical patterns of magnetic reversal. And it is all too apparent that you can't get that gap in 6000 years. Wnt (talk) 06:00, 6 June 2011 (UTC)

In answer to the "deception" question, traditional beliefs have it that the first man was created as an adult. Similarly, the world was also created 'adult'. As this wonderfully anthropocentric view of the universe goes that everything was created in order for man to be put in it, creating it already old (and ready for mankind) makes perfect sense. To read into this "deception" is the input of the viewer, not the creator. --Dweller (talk) 13:23, 6 June 2011 (UTC)

There is a theological term for the concept that God created the Universe "in media res" as it were, with light waves already on their way from distant stars, and trees with internal rings denoting seasons that never existed, and rivers with beds they had never gouged. But I cannot remember what it is, although I will look it up and get back to y'all.

And it was said (in the past and only by a very few) that God made it thus to challenge our faiths in the Word. However, in contrast to what many of the preceding posters have written, VERY few fundamentalists take this road. It is a most unsatisfying explanation, and even for them has a absurdly ad hoc quality to it, especially when we realize that it follows that everything could have been made 5 minutes ago. I suspect that many of the posters who have written to characterize fundamentalists as taking this line have never looked into what they do say. The road they take is probably even harder to traverse. The vast majority of the young Earthers insist that the evidence, properly considered, DOES show that the world, indeed the whole Universe, is only 6000 years old, and that scientists are variously deceived by the Devil, too proud to accept the Bible as the real authority, conniving in hiding and discarding evidence which does not support their evolutionistic theories, denying funds and airspace to alternative views and so on. Myles325a (talk) 08:41, 7 June 2011 (UTC)