Wikipedia:Reference desk/Archives/Science/2010 August 9

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August 9

What manner of turtle is this?

I saw this turtle about a quarter mile away from the Olentangy River in Columbus, Ohio, on a rainy afternoon in June. What kind of turtle is it? Thanks. —Preceding unsigned comment added by 98.28.19.62 (talk) 00:36, 9 August 2010 (UTC)

Apalone mutica, the smooth softshell turtle, I think. Deor (talk) 01:01, 9 August 2010 (UTC)

Conservation of matter argument for Climate Change and Alternative energy?

Before the Great Oxygenation Event (GOE) about 2.4 BYA there was no, or very little, free oxygen in the atmosphere. Now there is 78% nitrogen, 21% oxygen and 0.0387% carbon dioxide. A portion of the carbon that used to be in the atmosphere is locked up in fossil fuels. Do we have any idea how much carbon is locked up as fossil fuel? I used to think that burning fossil fuels is effectivley undong the GOE, this seemed to me a good argument for alternative energy which didn't really rely on whether or not you "believe" in global warming. However, the articles about fossil fuels indicate that our FF reserves are mostly 300-600 million years old. Does this mean there is a whole lot of GOE Carbon locked up somewhere other then fossil fuel? Obviously "current" life (forests etc) has some carbon locked up, but as a percentage is that a big protion or a small portion? Or a tiny portion? How much fossil fuel IS there available to burn? And if we burn it all, or a good portion, can't we predict how much more co2 there will be in the atmosphere? Or are things like the ocean carbon sink too hard to predict? Even if we don't "undo the entire GOE" isn't increasing the CO2 level by 100 or 200 parts per million considered quite bad? So what would happen if we got to 0.1% or 0.5% atmospheric carbon dioxide? Is that really so "unlikely" at our current pace of emission? Sorry i know this is a bit all over the place.. Vespine (talk) 05:17, 9 August 2010 (UTC)

Well, the GOE was an oxygen event, not a carbon event. But more relevantly, the account above leaves out major parts of the carbon cycle. Most of the Earth's carbon is in the mantle, and this source gets into the atmosphere via volcanic activity. Also, atmospheric CO2, because it is acidic, reacts with rock via a process called weathering to give rise to carbonates. These carbonates end up on the sea floor eventually, and sooner or later the sea floor gets subducted and takes the carbon back into the mantle. All this is very slow, but it's fast enough to have recycled the entire sea floor several times since the GOE. The bottom line is that the carbon cycle can't be understood by looking only at atmospheric carbon, fossil fuels, and the biosphere, it's also necessary to take into account mantle carbon and carbonate rocks.

Regarding how much fossil fuel there is, the amount of oil is limited, but the amount of coal is huge, hundreds of years of supply even if we burn it as fast as we can. Looie496 (talk) 05:50, 9 August 2010 (UTC)

The burning of fossil fuels does lead to a measurable decrease in atmospheric oxygen. This is one of several pieces of evidence that let us know that the increase in atmospheric CO₂ is, without any reasonable doubt, anthropogenic. However, if you look at the stoichiometry, it takes one molecule of O₂ to produce one molecule of CO₂. We have burned fossil fuels worth very roughly about 200 ppm of CO₂ (about half of which is in the atmosphere, the other half has gone into other sinks). 200 ppm is 0.02%, so the effect on oxygen levels is relatively small. --Stephan Schulz (talk) 07:06, 9 August 2010 (UTC)

Are you saying that this 200 ppm ATM reduction of O₂ has been measured? -- 119.31.121.66 (talk) 12:36, 9 August 2010 (UTC)

No. As far as I know, we have reliable records for atmospheric O₂ only since the mid 1980s or so. But since then, decrease in oxygen has been largely in inverse lock-step with anthropogenic CO₂ emissions (there are some subtleties because CO₂ is much more soluble in sea water than oxygen is). --Stephan Schulz (talk) 12:57, 9 August 2010 (UTC)

From Falkowski et al., Science, 2000:

Region	Gigatons of C (GtC, 1012 kg of carbon)
Atmosphere	720
Oceans	38,400
Total inorganic	37,400
Surface layer	670
Deep layer	36,730
Total organic	1,000
Lithosphere	>75,000,000
Sedimentary carbonates	>60,000,000
Kerogens	15,000,000
Terrestrial biosphere (total)	2,000
Living biomass	600-1,000
Dead biomass	1,200
Aquatic biosphere	1-2
Fossil fuels	4,130
Coal	3,510
Oil	230
Gas	140
Other (peat)	250

Most of the GOE carbon ended up as sedimentary carbonates and kerogens. The amount of carbon that can be burned as fossil fuels is large compared to either the atmosphere or the biosphere, but infinitesimal compared to the amount of carbon that has been incorporated into sedimentary rocks in forms that are not useful for combustion. Burning all of the fossil fuels would be bad, but it would only barely make a dent in the amount of oxygen that exists in the atmosphere. Dragons flight (talk) 07:54, 9 August 2010 (UTC)

That's some really great answers, precisely the kind of information I was looking for. Thanks everyone. Vespine (talk) 03:30, 10 August 2010 (UTC)

Present day radiation levels at Hiroshima and Nagasaki

I was wondering if anyone knew the present day radiation levels above normal at ground level, if any, in Hiroshima and Nagasaki? Thanks. 150.49.180.199 (talk) 05:48, 9 August 2010 (UTC)Mark

I don't have a source for this but I was under the impression that Hiroshima now has the same levels of radiation as the global average. This is because the bomb exploded in the air rather than on the ground, and irradiated air moves on eventually. If it had exploded on the ground, I would expect the perseverance of the radiation to be much worse. Someone feel free to shut me up :) Regards, --—Cyclonenim | Chat  09:47, 9 August 2010 (UTC)

No need to shut you up, you're right. From the little boy article, "Because Little Boy was an air burst 1,900 feet (580 m) above the ground, there was no bomb crater and no local radioactive fallout." The statement has this reference. I would dangerously assume that the conditions were the same for the fat man explosion. Ks0stm ^(T•C•G) 09:50, 9 August 2010 (UTC)

The very first Google search result for 'radiation level hiroshima' [1]. Bing isn't so good (IMHO) finding a bunch of Yahoo answers and other things but does find [2] as the 9th result (6th on Google). Google also finds RERF as the 4th and [3] (see q12) as the 9th result. RERF which I highlighted is perhaps the best of those resources. Nil Einne (talk) 09:59, 9 August 2010 (UTC)

An article "Residual radiation in Hiroshima and Nagasaki"[4] is available for payment from The Lancet. Yahoo Answers says that radiation from the bombs is long gone[5]. Cuddlyable3 (talk) 15:16, 9 August 2010 (UTC)

Is there a reason you continue to cite sources like Yahoo! Answers even though they are clearly not reliable? Do you even read the responses before you cite such things? The Lancet is at least a reliable source but the abstract makes it pretty clear (which I then verified with the actual article) that the article in question is only talking about residual radiation in 1946, not the present day. It is entirely inapplicable to the current discussion. --Mr.98 (talk) 15:52, 9 August 2010 (UTC)

Yeah - Yahoo! Answers is just another "asking random people on the Internet" site - just like this one - except that their reliability has been shown to be vastly worse than ours. We shouldn't reference them because the probability of improving our answer is worse than chance! SteveBaker (talk) 22:40, 9 August 2010 (UTC)

The Marangoni Effect in a wineglass

I recently posted a question concerning the toroidal motion of sediment in the base of a near-empty wineglass (the content was that which had gathered in the bottom over a roughly fifteen minute period). I noted that even though the glass had not been touched for this period and that there were no obvious sources of vibration energy etc. the sediment continued to move in its toroidal pattern seemingly without further input. The Marangoni effect was suggested and I think, having researched this penomenon's various manifestations, that I agree that this is what was going on. My question now concerns the 'actors' in this instance. The Marangoni effect has been presented by various sites as transfer caused an inequilibrium of some sort, be it density, alcohol concentration or whatever, with tantalising hints that surface tension differences point to a more correct interpretation. In my wineglass example, what are the sources of this imbalance? I am assuming that water and ethanol are the major parties and that the sediment simply makes the effect more readily visible, but what is the nature of the inequilibrium and how are the two liquids interacting to resolve it? Also, why does this only happen with a near-empty glass and not a full one (assuming that this observation is true, naturally). I am researching this for a book (fiction) and want to get my facts straight as the explanation is to be given by a (again fictional) professor of fluid dynamics and to an individual who is scientifically literate albeit in a different field.

Thank you in advance.

--Mark David Ward (talk) 08:01, 9 August 2010 (UTC)

Mark's previous question, and the responses, can be seen at Mysterious movement of sediment in a wine glass. Dolphin (t) 08:59, 9 August 2010 (UTC)

I would speculate that the reason this only happens with a near-empty wine glass is because of the amount of energy required to make this start (and continue). The less liquid, the less energy you need. If surface tension or evaporation is implicated, it is also the case that the less liquid there is, the larger the surface-area-to-mass ratio (assuming a roughly hemispherical bottom to the glass). I kinda wonder (without any particular evidence/math to back it up) whether there is some kind of conservation of rotational inertia going on here. Is it possible that a slow motion rotation of the bulk liquid is somehow 'concentrated' into the bottom of the glass as you consume the wine?

We get quite a few questions about the weird behavior of liquids in cups and glasses - they are interesting science - but really tough to answer well! SteveBaker (talk) 22:37, 9 August 2010 (UTC)

The way a slow rotation of the bulk liquid is concentrated into an anomalous activity near the center of the bottom of the glass (and other weird behaviour of liquids in cups and glasses) may be the secondary flow of the boundary layer on the floor of the glass. See Secondary flow#Circular flow in a bowl or cup. Dolphin (t) 05:44, 10 August 2010 (UTC)

Thank you both for your answers, I appreciate the time it takes. One thing I would really like to know though is the nature of the disequilibrium in the wine. Does it concern water and alcohol? If so, what is it about them which makes the disequilibrium appear and how does the motion resolve it? I take the point made about the smaller amount of energy required to move a small amount of liquid making this effect more likely to occur in a near-empty glass, but I wonder if it occurs all the time, near the surface, and is only visible in a near empty glass is that when the glass is near empty, the sediment is naturally involved where it hopefully would not be in a full glass. My theory concerning this effect is that the alcohol water are simply well mixed - the alcohol is not dissolved in the water, or vice-versa, so at the surface there will be a mixture of water molecules and alcohol molecules in contact with the air. The alcohol is less dense than the water and so, given sufficient time will tend to rise, but I suspect that inter-molecular forces will reduce this to a near negligible effect; otherwise alcohol would separate out in stored wine etc. The alcohol is also more volatile and so, will evaporate more readily. I suspect that this is a sufficiently strong effect to cause a gradient in alcohol concentration which drives the motion until the alcohol runs out. Actually, in explaining my thoughts, I realise that I understand this even less well than I thought. Help someone! :)

--Mark David Ward (talk) 18:51, 10 August 2010 (UTC)

Cricket type

I'm looking for a specie of crickets. It is brown with a little orange tail, and can be found here in The Netherlands, I fond alot of them in the dunes. Aeno•talk to me 13:07, 9 August 2010 (UTC)

Chorthippus brunneus

Chorthippus brunneus[6] is called the Common Field Grasshopper in English. "The mature male becomes reddish orange at the tip of the abdomen"[7]. I don't speak Dutch but this page[8] is entitled Bruinesprinkhaan Tandradje (Chorthippus brunneus). Alansplodge (talk) 18:35, 9 August 2010 (UTC)

Thanks! That's the one I was looking for. Aeno•talk to me 15:10, 10 August 2010 (UTC)

pollution

what are the effect of mine blasting on global warming? —Preceding unsigned comment added by Yashodeep1996 (talk • contribs) 14:10, 9 August 2010 (UTC)

Do you mean the use of explosives as part of the mining industry? In that case, there is basically no direct effect. Explosives probably release some greenhouse gases (aiding global warming). Explosions also produce dust (inhibiting global warming). Regardless, the scale is far below the industrial level needed to make a significant impact. One could also discuss the impact of explosives vs combustion-driven equipment vs raw human labor, but I expect that we're still well below meaningful amounts. As a secondary effect, mining can potentially have wide-ranging impacts, but then we've moved away from "blasting" to instead discuss the methods and/or products of mining. Finally, a note on why clarification is important: searching for "mine blasting" on WP predominantly returns results for land mines. — Lomn 15:00, 9 August 2010 (UTC)

According to http://cryptome.info/explosives.htm US explosives production was 2.53 Million tons p.a. in 2004 - assuming that could be the energy equivalent of TNT (TNT equivalent says 1 MT of TNT = 4.183PJ) that's ~10 PetaJoules of energy from explosives. Compare with energy use in the USA for electricity (List of countries by electricity consumption) of 3.9 petawatthours = 14040 PetaJoules - so the fraction is less than 0.1% (of energy from electricity not total energy)

Assuming all that explosion creates 3x as much mass of CO2 then that's ~7.5Million ton of CO2. The USA produced ~6500 million tonnes of CO2 in 2007 List of countries by carbon dioxide emissions so that is clearly about 0.1% of the total emmissions.

It does indeed seem to be a small amount relatively. (Hope my figures are mistake free).87.102.35.46 (talk) 15:43, 9 August 2010 (UTC)

Cement

Is this likely to be portland cement or could it be another type? The article on portland cement suggests that it's the most common type. ----Seans Potato Business 14:13, 9 August 2010 (UTC) I added the missing title. Cuddlyable3 (talk) 14:45, 9 August 2010 (UTC)

If you click on the "Health & Safety Information" box under "Features" on that page, the product heading is "Blue Circle Portland Cements", so I'd say that it's indeed Portland cement. Deor (talk) 14:55, 9 August 2010 (UTC)

More here http://www.lafarge-cement-uk.co.uk/mastercrete.html A "portland composite cement" , there's a pdf on the same page http://www.lafarge.co.uk/CementDatasheet/Mastercrete.pdf there's an improver added which is described in the pdf, it's still a portland cement.87.102.35.46 (talk) 16:28, 9 August 2010 (UTC)

Waking up

Just an up front notice that this isn't a request for medical advice, but general, practical advice.

I seem to have a serious problem waking up to alarms. Alarms, especially when I'm sleeping at home, seem to have a tendency to not wake me up. When I'm sleeping away from home, the effect of me sleeping lighter can occasionally overcome the inability of alarms to wake me up, but normally (and especially at home) I just sleep right through the alarm without even hearing it go off. When/if I hear it go off (wake up), I get out of bed with relative ease, it's just the fact that I don't wake up until after they've been going off for (at times) over an hour. The alarms that seem to do the best at waking me up are my cell phone alarm at full volume and this alarm called the "Screaming Meanie" that produces a noise so loud that it makes my ears ring for hours afterwords (It's never failed, I stopped using this one because I began to think it might be damaging to my hearing). What can I do to increase my ability to get up to alarms considering that I only have one year to acquire the ability before going off to college? In what ways can I maximize my chances of hearing the alarm on any given day? In short, how do you wake up to an alarm when you don't even hear it go off in the first place? Ks0stm ^(T•C•G) 19:12, 9 August 2010 (UTC)

Forgot to add that I do take medication to help me sleep (thus the "I'm not requesting medical advice" disclaimer"), and it does negatively affect my abilities to wake up in the morning. Ks0stm ^(T•C•G) 19:27, 9 August 2010 (UTC)

Go to bed earlier? --Chemicalinterest (talk) 19:32, 9 August 2010 (UTC)

Phone alarms that I've heard tend to be quite...nice. Find a sound that's really really annoying (you may even be able to download such a sound for your phone alarm). 90.195.179.60 (talk) 19:40, 9 August 2010 (UTC)

For example, I find this sound to be unbearable. http://www.youtube.com/watch?v=no4elRUgxmY#t=58s 90.195.179.60 (talk) 19:43, 9 August 2010 (UTC)

If your difficulty waking up is as a result of taking sleeping pills, then its a side-effect of the pills and not something we can help with, since that would be medical advice. You need to talk to whoever prescribed the pills. --Tango (talk) 20:01, 9 August 2010 (UTC)

Option 1: Get a random alarm. Don't increase the volume. Your subconscious listens to the sound and decides if it's important enough to alert you to it. After a while you will get used to an alarm sound, and it will no longer be considered important. But if you give it a new sound it won't know what to do with it. Option 2: You can also train it. During the day play the alarm and as soon as you hear it jump up and be very active - get to the point that it's automatic - you hear the sound, you jump, without even thinking about it. Additional Note: If you are medicated you may be physically unable to wake up, and no alarm will work. Talk to your doctor about the dose. Ariel. (talk) 20:04, 9 August 2010 (UTC)

Sounds like you've got caffeine addiction, or at least you are not getting enough sleep. Give up tea and coffee, go to bed earlier. 92.15.27.40 (talk) 20:20, 9 August 2010 (UTC)

You have a wall of text, so I didn't read it, but have you tried doing nothing more than putting the alarm across the room and seeing if you get up and turn it off then? Secondly, before you go to sleep, reflect on the number of hours you will sleep (count): picture that many hours, then picture yourself getting up afterward. Finally, if you are not going to get at least 6 hours, set the exact time to be an increment of 90 minutes (or 45) from when you will fall asleep (7 to 15 minutes after you set the alarm.). If it's 2:20 AM and I have to get up at 4:15, no way would I be able to do that, I would totally sleep through any alarm. So, I've showever and brushed my teeth, then count 2:20 AM plus 90 minutes is 3:50, and until 415 that's exactly 25 minutes or smack-dab in the middle of a cycle. I will set it for 3:50 instead, reflect on the 90 minutes of sleep I'm about to get, and fall asleep. I get up on time, and won't be particlularly tired until 4-6pm the next day, when the hour and a half of sleep will cath up with me. My point is, if instead of an hour and a half it had been an hour and fifty-fie minutes, no way would I have been able to get up.

of course, the best policy is to go to sleep on time: no caffeine after 6 pm!! 85.181.49.221 (talk) 21:01, 9 August 2010 (UTC)

Ironically, you were unable to read the OP's "wall of text" (253 words), and yet you responded with your own "wall of text" (256 words), which was even more pointless given that you had not bothered to read the question. If that's the best you can do, you're better off not answering. --Mr.98 (talk) 01:16, 10 August 2010 (UTC)

It's not that long a question and had you read if you would have learned that the OP has no difficulty getting up once awake, the problem is waking up. --Tango (talk) 22:25, 9 August 2010 (UTC)

I found that waking up to a talk-radio station - or using a talking alarm clock ("The time is six forty-five A.M."...updating every 5 minutes) - works much better than music or beeps/bells/squawks, etc. Evidently the sound of voices does the trick for me. I don't think volume is the answer.

SteveBaker (talk) 22:29, 9 August 2010 (UTC)

I'm with Steve. Try something other than an alarm noise. I found that when my clock made loud alarms, I would instinctively mash the snooze button and go back to bed without even remembering doing so. I only realized it had happened when I eventually woke up (much) later than intended. After switching it to play music instead, sometimes a really good song will happen to be on the radio and I'll stay awake a few minutes to listen to it. By the end, I'm about ready to get up. Worth a shot. 75.157.57.12 (talk) 08:38, 10 August 2010 (UTC)

If the sound of an alarm doesn't wake you, how about buying a vibrating alarm clock? There appear to be a lot on the market, aimed at those who are deaf or hard of hearing. Smartse (talk) 22:40, 9 August 2010 (UTC)

There are various ingenious alarm clocks which will start Rube Goldberg devices to pull off the covers, vibrate the bed, dump you out of bed on the floor, make louder and louder noises, etc. My deaf niece has an alarm which shakes the bed, so such things are readily available. A silent movie by Thomas Edison from the early years of the 20th century had a man who couldn't wake up tie a rope to his ankle and leave it dangling out side the window, for his friend to tug on it in the morning and wake him up. Naturally hilarity ensued with a drunk yanking on it, etc, and eventually a wagon getting tied to it , with the horse setting off and dragging the sleeper out the window and through the town. Therefore I do not recommend the ankle rope through the window routine. "Inability to wake up" sounds like a medical issue, although I have known young adults in whom it seemed to be a form of rejection of responsibility and passive aggression where sleep medication was not involved. "Alarms don't wake me up" might be a form of rejection of responsibility, like "It's Mommy's job to get me to high school on time." No, it's your job, no one else's. If the alarm clock gets louder and louder, eventually it will annoy the dorm neighbors, who will pick the room lock and dump icewater on the sleeper or shoot him with pepper spray until he learns to get up and be a productive member of society. Or he will flunk out of school due to missed exams, or get fired from his job. Edison (talk) 01:47, 10 August 2010 (UTC)

Oddly, I find visualisation really helps me wake up at the right time. While lying in bed before going to sleep, I picture the current time, and picture the time I need to wake up, and think about those and the time difference between them. I think to myself that I must get up at that time, or I won't have time to get ready and leave the house. I picture myself getting up quickly and immediately at that time, and do a quick imaginary run-through of the first few minutes of my morning routine. I've had real problems waking up to alarms for a while, but when I do this I manage much better. The only problem is that it can lead to anxiety, if not done carefully, which then makes it harder to get to sleep in the first place! 82.24.248.137 (talk) 22:01, 10 August 2010 (UTC)

Q: Today's featured pic

File:Seven Sisters Panorama, East Sussex, England - May 2009.jpg.

What's in the yellow mounds on the green (top right) ? East of Borschov 21:04, 9 August 2010 (UTC)

It's hard to tell at this distance, but it may be gorse or heather, flowering yellow. -- Finlay McWalter • Talk 21:12, 9 August 2010 (UTC)

My guess would be gorse - while it's hard to get the scale on a picture like that the plants look rather too tall for most heathers. But yes, it could certainly be either. ~ mazca ^talk 21:55, 9 August 2010 (UTC)

There are lots of types of common yellow flowers in that part of England - it could be buttercups or any of half a dozen other things. What's odd about the picture is that the yellow patches are only visible on top of clumps of dirt - not on the flat grassy bits. I suppose the exposed dirt might get re-inhabited by flowers before the grass can take over and choke it out or something. It's hard to tell without a closer inspection. SteveBaker (talk) 22:24, 9 August 2010 (UTC)

Steve, if you go to full resolution (the picture is huge) it's very obvious that the plants are flowering low bushes, not small ground flowers on 'clumps of dirt.' 87.82.229.195 (talk) 10:01, 10 August 2010 (UTC)

The harsh environment of a hilltop precludes most meadow and forest wildflowers, and the proximity to the sea make it worse. You do find flowering plants in a seaside Machair environment, but this is the wrong location, altitude, and geology. That leaves very hardy low-lying shrubs - if it's not heather or gorse, it's something of a similarly tough, and mostly inedible, disposition. The "clumps of dirt" are just the non-flowering bits of the shrub. -- Finlay McWalter • Talk 22:36, 9 August 2010 (UTC)

I'm certain it's gorse; *When gorse is out of blossom, kissing's out of fashion"[9] (old English saying). Alansplodge (talk) 02:30, 10 August 2010 (UTC)

I agree, it is almost certainly gorse on the grounds that I cannot identify an alternative. Yellow heather is possible but very unlikely given the alkali nature of the soil. It might be dwarf gorse, but again it is out of its normal habitat. Richard Avery (talk) 07:52, 10 August 2010 (UTC)

Crayfish in New Jersey streams

What crayfish is this?

What is this crayfish? It has a dark brown shell and is rather large. I found it in a local stream in New Jersey. --Chemicalinterest (talk) 22:25, 9 August 2010 (UTC)

Only a guess but Signal crayfish seems to fit. The one in the picture I wouldn't describe as "rather large" however. If not that it could be one of the other Pacifastacus but there isn't really enough info on most of the others to make a guess.. Vespine (talk) 03:42, 10 August 2010 (UTC)

It is the less common crayfish. The more common ones are lighter brown 2 cm (1 inch) long crayfishes. They are found in all other streams. These range from 2 cm to about 8 cm. --Chemicalinterest (talk) 11:01, 10 August 2010 (UTC)

Rusty crayfish? Not enough description though. --Chemicalinterest (talk) 13:51, 10 August 2010 (UTC)

Having a look at google images, maybe I was a bit too ambitious thinking I could have a reasonable guess, lol.. The subject looks a lot more complicated then I initially thought, looks like I even got the family wrong! I'd say your guess looks better then mine. Vespine (talk) 23:01, 10 August 2010 (UTC)

See WP:Wikipedia is not a field guide, a nonexistent rule that everyone follows. --Chemicalinterest (talk) 14:43, 11 August 2010 (UTC)

I dunno..I've learned more about sea gulls on these desks than I ever expected. Pfly (talk) 10:13, 14 August 2010 (UTC)

Looking for reference for an experiment about expectations and performance

I remember seeing on TV something about an experiment relating expectations and academic performance. In the experiment, students were divided into two groups and given identical math problems. One group was told that the problems were difficult. The other group was told something different, I think something to the effect that they should try hard, or something similar. In the end, the group that expected the problems to be difficult (and beyond the students' abilities?) did worse than the other group. I'm writing this from memory so I might have got some of the details wrong. Does anyone know what experiment that was? --71.185.169.212 (talk) 23:12, 9 August 2010 (UTC)

This sounds similar to the Pygmalion effect, and it reminded me of a story about George Dantzig. Ariel. (talk) 06:15, 10 August 2010 (UTC)

Three meals a day?

I've been thinking: A lot of people who are obese start out overeating by eating past satiation thinking they need to "stave off" hunger until the next meal, and misjudge how much they need. If people always only ate just enough to feel satisfied and did this again everytime they felt hungry rather than eating the standard 3 meals a day, would they keep gaining weight? And how much would this differ based on the quality of the diet? 68.76.158.13 (talk) 23:14, 9 August 2010 (UTC)

There are those that claim people should eat small meals regularly throughout the day. They claim this raises the basal metabolic rate and regulates insulin levels. This article discusses one such diet, and its critics - it seems there isn't enough evidence to know for sure. Similar advice (with similarly scientific sounding reasons) is often given to bodybuilders (e.g. bodybuilding.com, wikihow). All of these are more to do with claims about metabolism and insulin levels, and not so much about your "eat when you're hungry" theory (although hunger and insulin are related). -- Finlay McWalter • Talk 00:13, 10 August 2010 (UTC)

For many fat people, hunger is more psychological than physiological. If they see someone eat something good, they suddenly become unbearably hungry regardless of stomach fullness or blood sugar. If they smell fresh baked doughnuts, they are suddenly hungry. Hunger may attack 30 minutes after a big meal if something tasty is seen. Edison (talk) 01:33, 10 August 2010 (UTC)

For some people the "I'm hungry" meter is set wrong, and causes them to desire more calories than they need. So even if they obey hunger perfectly they may still become fat (i.e. they need 100, they want 110, so over time they get fatter and fatter). In other people the "perfect weight" setpoint is simply set high. So if they go lower then get extra hungry, but if they reach it then calories desired matches calories needed and they simply stay at that weight. So to answer your question: No. That would not solve the problem in many people. (But it would in some.) Ariel. (talk) 06:06, 10 August 2010 (UTC)

There is also the issue of people responding to "I'm thirsty" by eating instead of drinking water. That is the reason that liquid diets tend to be slightly successful in some people. It suppresses the "I'm thirsty" trigger. It does absolutely nothing for people who overeat for other reasons. -- kainaw™ 06:16, 10 August 2010 (UTC)

To go back to the original post one cannot disagree with the idea that if most people ate less they would be thinner. This is similar to the idea that if everyone drove a little slower there would be less accidents and deaths on the roads. The development of obesity is multifaceted and varies with individuals. The basic problem is overeating, but the causes of overeating are more complex than just feeling hungry at the sight of attractive comestibles. We have to consider self esteem, the inability of the individual to notice changes in body shape, the denial of a person to accept their obesity, the social acceptability of obesity, the insistent advertising by commerce, the increased availability of food, the increasing use of inappropriate ingredients in foodstuffs . . . and so on. Obesity is here to stay, and probably will worsen in the future.steps off soap-box. Richard Avery (talk) 07:34, 10 August 2010 (UTC)

Completely disagree. People eat too much for different reasons, and lack of access to healthy and nutritious food, large portions, lack of exercise, and a sedentary lifestyle supported by automobile transportation, television habits, gaming and internet, and desk-related work are all big contributors to obesity. Once you address all of these factors, you are well on the way to controlling your weight. Losing weight requires changing your entire lifestyle, and most people will not take that first step. Viriditas (talk) 03:37, 11 August 2010 (UTC)

Modern food has many calories in relation to its bulk from fat and processed carbohydrates (eg bread, pasta). It has also been designed to be very tasty and nice to eat. Bulk weight and fibre satiates hunger, not calories. Thus we overeat. I think eating a lot of vegetables and fruit while avoiding processed foods is the way to avoid weight gain without hunger. But evolution did not design us to cope with food always being available. See http://nutritiondata.self.com/topics/fullness-factor 92.29.121.47 (talk) 10:40, 10 August 2010 (UTC)

How are bread and pasta "modern"? Bread has been around for millennia and pasta for at least a few centuries (its exact origins are disputed, it could easily be a couple of millennia old as well). Also, wouldn't something that satiates hunger without providing calories tend to make us undereat, not overeat? --Tango (talk) 11:04, 10 August 2010 (UTC)

You may be surprised, but bread and pasta are certainly not archaic foods and are currently available in many shops thoughout the world. I think I saw them for sale as recently as yesterday. Indeed, I consumed some myself a few days ago. I don't understand your comment about undereating, not something that most people (at least in the West if you want to pick pedantic hairs) will be in any danger from. 92.15.3.61 (talk) 16:06, 10 August 2010 (UTC)

From what you've said so far, how are bread and pasta any more 'modern foods' then vegetables and fruit?

Also I think Tango misread, as did I, your earlier comment. You said "Modern food has many calories in relation to its bulk from fat and processed carbohydrates (eg bread, pasta). It has also been designed to be very tasty and nice to eat. Bulk weight and fibre satiates hunger, not calories. Thus we overeat"

Reading carefully, it seems what you're saying is "Bulk weight and fibre, not calories, is what's needed to satiate hunger. But modern food has many calories compared to bulk. Therefore we overeat."

However if don't read carefully, it sounds like you're saying "Modern food has bulk weight and fibre which satiates hunger but doesn't satiate calories, therefore we tend to overeat", which doesn't make much sense (if that were the case, people would tend to undereat not overeat).

BTW, the acknowledgement it's only in certain areas that most people aren't at risk of undereating is an important want, since there are indeed a very large number of people who are at risk and they shouldn't be ignored. They don't relate to this question, but you should still specify what you're talking about instead of making broad-brushed claims.

Nil Einne (talk) 19:03, 11 August 2010 (UTC)

"How are bread and pasta any more 'modern foods' then vegetables and fruit?" Do not take this the wrong way, but the above posting and other even lengthier postings in the same vein by the same author matches as far as I can see as a layperson to the description in the section Aspergers#Speech_and_language. 92.15.14.45 (talk) 21:18, 11 August 2010 (UTC)

Wait, so now you're saying you have Aspergers? How is that relevant to your strange claim that bread and pasta are 'modern foods', as opposed to foods which have been around for centuries (and are still eaten)? Notice you are the only one who treated 'archaic' as the opposite of 'modern'. 82.24.248.137 (talk) 16:52, 12 August 2010 (UTC)

Don't troll please. 92.24.190.46 (talk) 10:22, 13 August 2010 (UTC)

Well, historically, the Early modern period began in Europe more then 500 years ago... Googlemeister (talk) 13:23, 10 August 2010 (UTC)

Skipping breakfast will simply make you more fat. ~AH1^(TCU) 23:52, 10 August 2010 (UTC)

Very interesting thread, the original poster is right, there are several study trials which have been conducted and have unanimously opined that smaller frequent meals DO INDEED reduce obesity. A quick search of national library of medicine ( www.nlm.nih.gov) will give you details of several trials which have come to the same conlusion. Smaller quantity, frequent meals definitely trigger insulin release and help in carbohydrate breakdown, it helps prevent distention of abdomen and also helps increase the basal metabolic rate. So the original poster is spot on and as a medical practitioner I have to agree with him/her. However, the subsequent posters have also presented valid facts, fighting obesity isnt a unidimensional battle. You just cant control diet alone and hope to win the battle against the bulge. Lifestyle modifications, fitness exercises and mental discipline are very important factors too. --Fragrantforever 07:16, 11 August 2010 (UTC) —Preceding unsigned comment added by Fragrantforever (talk • contribs)