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Terminal velocity for raindrops is around 9 m/s (slower for smaller drops, like drizzle). Acceleration is 9.8 m/s/s. So big raindrops reach terminal velocity in 9/9.8 = 0.9 seconds, during which time they fall 0.5*a*t*t = 0.5*9.8*0.9*0.9 = 4 metres = 13 feet.

Anything's possible. But that's extremely unlikely. The cable installers would have to be absolute morons not to include at least a couple feet* of slack, and you don't hire that sort of monkey to do this sort of job.

*This is how slowly the tectonic plates move, and why I didn't type "a couple hundred miles" above:

http://hypertextbook.com/facts/ZhenHuang.shtml

Assuming I'm reading these correctgly, the energy density of ethanol is between 23 and 26 megajoules per kilogram. The energy density of Gasoline is about twice that, 45 MJ/Kg. So this is about the equivalent of $2 per gallon of gas. A pretty good deal these days, not so much 10 years ago, unfortunately

Assuming I'm reading these correctgly, the energy density of ethanol is between 23 and 26 megajoules per kilogram. The energy density of Gasoline is about twice that, 45 MJ/Kg. So this is about the equivalent of $2 per gallon of gas. A pretty good deal these days, not so much 10 years ago, unfortunately

The answer to most of your above questions is "yes". You'll probably find that the speed of sound in steel and carbon is higher than it is in wood. The whole thing is almost by definition -- sound is a longitudinal wave (compression/rarefaction) and so transmits as fast as the medium will compress.

If you try to physically push one end of such a rod faster than the speed of sound in the material, it will break. (You can accelerate the whole thing gradually, but if you hit it with a high enough impulse it breaks or permanently deforms, because the energy can't spread down the rod fast enough.)

The speed of sound in air is a bit over 1000 fps (feet per second), in water it's a bit less than 5000 fps, and in structural steel it's a bit less than 15000 fps. Wood varies, but 13000 fps is a rough average. In beryllium (very stiff, very light), it's a phenomenal 42000+ fps. A search of various web sites turns up two different values for the speed of sound in diamond, the lower being about the same as that in beryllium, the higher being about 50% faster than that.

This page has a table of the speed of sound in various materials, and some explanations.

1. $100/mo buys a LOT of electricity and heat for someone living in a small apartment or basement suite. So we're not talking about someone living in a cold, unlit cave.

Let's get some datapoints with a google search.

http://www.homeabc.net/Other/2550-3-other.html
http://www.city-data.com/forum/dallas/116643-average-electricity-bill-3bdrm-apartment.html
http://message.snopes.com/showthread.php?t=23384
http://query.nytimes.com/gst/fullpage.html?res=9C0CE1DC153EF932A05756C0A966958260
http://boston.craigslist.org/gbs/sub/524170732.html

Arlington, 3bdrm: Multiple people saying >$200/mo
Vegas: 2bdrm, $150/mo
2bdrm house, location unknown, $60/mo
Florida 2bdrm apt, 17 years ago: $60/mo. Adjusting for inflation, $100/mo
2bdrm apt, location unknown, $150-$200/mo
2bdrm, location unknown: $80/mo
2bdrm, location unknown: $75-$90/mo
2bdrm, NC, using central air (more efficient): $60/mo
Boston, Unknown size: $40/mo
Irving, TX, 2bdrm: $300-$450/mo (poorly insulated and sealed)
"Average NYC apartment": $40/mo
Boston: $55/mo

Summary: Insulation is more important to size, and the further south you live (to an extent) in the US, the worse your bill will be because you tend to be relying on inefficient (but cheap) window units and are dealing with a lot of summer heat. Let's pretend that this covers electricity *and* gas, not just electricity. Looks like the average is around $50/mo up north and perhaps $180/mo down south. Crummy housing with low rent tends to be smaller but also less well insulated and sealed, so let's stick with these numbers.

Let's do the same for water:

http://goliath.ecnext.com/coms2/gi_0199-5812161/Unclog-your-plumbing-budget-the.html
http://query.nytimes.com/gst/fullpage.html?res=9C0CE3D71130F932A35754C0A966958260&sec=&spon=&pagewanted=all
http://hypertextbook.com/facts/2004/JosephSabatelle.shtml

One says the average is 80-150 gal/day, the other says 220 gal/day. Looks like water's typically around 2 tenths of a penny per liter. Going with an average 150gal/day at that price, that's $1.20/day, or $36/mo. Let's say only $40 with sewage added in.

Overall summary: A person in a hellhole up north wouldn't have to skimp. A person in a hellhole down south would be way overbudget and have to skimp like crazy.

2. People making minimum wage rarely buy healthcare, especially if they're healthy, as is being assumed here. If they become seriously ill, they're just fucked. It's sad, but true.

Thank you for making my point for me as to why so many of the poor don't own cars. It can be a choice between your health and transportation.

3. Furniture, TVs, etc, can all be acquired at no cost for anyone who actually knows other people.

Great plan. Because the poor are famous for giving away furniture, right? Lots of free furniture opportunities in Compton, right? The poor spend all their time hobknobbing, right?

Yes, you can get free furniture. But it's an unreliable source. The poor make do with whatever they can get. If "whatever they can get" is nothing, then they make do with nothing. If "whatever they can get" is falling apart, then they make use of that, too. One insidious problem is that the less money you have, the more you need. For example, if you'

A rule of thumb quoted ofter during my skydiving days (I made about 1400) was that it took some 8 or 9 seconds to achieve a terminal valocity of about 120 mph. Experience gives me a good feel that this is accurate since it takes about that long after jumping before you can do freefall manuevers effectively.

At one time, there was such an event as skydiving style, in which the jumper would get into a compact tucked position to achieve a higher speed (and more manuevarability). Nowadays, skydivers can achieve high speeds by going into a stable head down position.

Exhaustive links, references here and here.

As closely as I can figure it, there are about 11_515_262_616_000 metric tons of Uranium-235 in the earth's crust.

The numbers work out as follows: The mass of the earth is about 5.98e24 kilograms. The crust is about .099% of that. Uranium occurs at a rate of about 2.7 milligrams per kilogram in the crust, and about 0.7204% of that is Uranium-235.

Some of that would undoubtedly take more energy to mine, purify and enrich to usable levels than it would produce as output -- but even if only one percent is usable, it still works out to quite a large energy supply. Enrichment isn't necessarily needed -- but if you don't enrich the Uranium, you typically also have to moderate your reactor with deuterium, and it takes a fair amount of energy to purify deuterium from normal water as well. In any case, once you've purified the Uranium, enrichment is roughly a fixed cost regardless of the original source.

There's also Uranium in sea water, though the rate is quite low (3.2 micrograms per liter). That might be a practical supply as well, but I don't know enough about how difficult it is to purify from sea water to be certain. My immediate guess is that if the only alternatives were things like solar or wind power, somebody could figure out a practical way to do it.

Cow body temperature: 38.6C

about 50 microteslas http://hypertextbook.com/facts/1999/DanielleCaruso.shtml.

according to the Fine Article:

The measurment field in the article is 46 microteslas.
(A "pre-polarization" field of 30 mT (milliteslas) is appled for one second before each meaurement)

Other interesting magnet & strengths.

Hit submit instead of preview by accident, rest of post

As to the laughable post I saw further down that indicated gold was akin to snake oil? Somebody needs to take an electrical refresher course. Gold IS a better conductor than copper, it just costs too damn much to wire everything with so we go with the next best alternative. However in high(er) end theatre setups (mine tops $10k without the cables) gold connectors are the way to go.

Gold is WORSE than copper at conductivity.

Gold: 22.1 (lower is better)
Copper: 17.1
Silver: 15.9
Iron: 96.1

What makes Gold good for connectors is that it doesn't corrode or oxidize like copper/silver will, oxidation increases resistance.

For the record; when you're on the cusp of making a $5000 equipment purchase it's quite easy at that point to convince the salesman to throw in some Monster cabling gratis. That's how I get the quality of the Monster cables without suffering the ridiculous markup.

Then you paid the right price for them; none of us will argue with using monster cables if you got them for free.

This seems to be at odds with the rest of your post. I'm confused; you admit that you can suffer pops and static using cheap cables for digital audio, but you don't believe in high-end shielded digital audio cables?!?

Because the signal will make it through intact on any half decent cable that meets specifications? Heck, in my earlier post the cheapest cable still had shielding. Better quality cable enables longer runs before interference shows up- not better sound.

We're not talking 'bottom line' here, we're talking 'sub monster generic cables that are still well constructed'.

The longest continuous space trip by a crew (with no gravity... none) was 438 days... that's just over 1.2 years. Another single Cosmonaut managed one day beyond that.

Sure, the three guys who pulled it off were pretty much stuck in a convalescence home for nearly a year before they could walk again, and had to exercise their asses off every day they were up there, but point is that they did manage.

With 0.16 G , one would think you could stretch that out a bit to at least a year-and-a-half (perhaps more) before it got as bad as it did for the current record holders, no? This isn't even counting medical remedies and techniques that weren't available in earlier long-duration spaceflight tests.

/P

Yeah, the bastards should of used the 256 Hz Scientific Scale

Even completely unhindered shot from a shotgun pellet wouldn't even get close to traveling 1 kilometer. According to this research, a shotgun pellet only travels about 45-50 meters. Even a .22 long rifle has a maximum range of about 2000 yards.

We send a person to walk around on the moon, but it's impossible to shoot down a missile? Tell me another one.

No, it's simply impossible, with current technology, or anything we are likely to develop in the near future, to reliably shoot down a high enough percentage of incoming MIRVs on polar trajectories to make a massive nuclear attack survivable without an unworkable ratio of interceptors to targets. You see, a missile is what we call rather small (a few dozen meters in length, a few meters in diameter) and moves very, very fast and very, very unpredictably, while the moon is what we call very, very big (3.5 million meters across), and while it is also very, very fast, it's movement is also very, very predictable.

Objectivity on climate change is not an instance of it.

"Objectivity is whatever I say it is!"

That and Doom-Through-Impending-CO2-Poisoning are examples of people, whether politicians or scientists, trying to gain political advantage through bastardized science.

Not CO2 poisoning, but "greenhouse effect" warming: our ideas about global climate change are largely informed by our studies of the Venusian atmosphere in the 1960s, and global warming was predicted long before evidence of temperature increases were actually measured (just as the depletion of the ozone layer was predicted long before the Antarctic ozone hole was discovered). The funny thing is that all the arguments against global climate change appear to be coming from a specific ideological position, while many of the arguments in favor of global climate change are coming from different ideological positions (and the "science" in opposition is mostly a matter of saving the phenomena, i.e., multiplying entities in an attempt to find benign explanations for observed phenomena, and attacking opposing positions not on their science, but on their supposed ideological motivations; the only rational argument I've seen against global climate change is the questioning of the "hockey stick" graph, and that merely holds force against predictions of the rate of climate change, not its existence).

• The energy density of petroleum is about 45MJ
• The energy densite of ethanol is about 23MJ
• There's a Wikipedia article on fuel energy balance which cites a figure of 1.24 for ethanol, and has links to various PDFs
• Lastly, try the library back issues of Scientific American for 2007. I just threw away a stash, and one of them covers the production of ethanol from start to finish, and talks about how tight the net energy gain is, and how subsidies are skewing it. It might have a comparison to oil, but I don't remember

• The energy density of petroleum is about 45MJ
• The energy densite of ethanol is about 23MJ
• There's a Wikipedia article on fuel energy balance which cites a figure of 1.24 for ethanol, and has links to various PDFs
• Lastly, try the library back issues of Scientific American for 2007. I just threw away a stash, and one of them covers the production of ethanol from start to finish, and talks about how tight the net energy gain is, and how subsidies are skewing it. It might have a comparison to oil, but I don't remember

I'd definitely argue that the existence of life on other planets is pretty much a foregone conclusion, although even that argument does rest on a certain belief structure. There are several unknown quantities involved, so I don't think one can argue rigorously that there must be life on other planets.

OTOH, I was definitely talking about sentient life, which takes an additional amount of belief. Just like you're certain that life must be out there because as you keep adding more planets, life is a statistical certainty, I would argue that as you keep adding more planets with life, sentient life is a statistical certainty. Maybe only an average of one per galaxy on average, but that would still mean that the universe has billions of races of sentient life. (Who will in that case, of course, never hold a meaningful conversation with each other - except possibly for those lucky few hundred thousand who happen to share a galaxy, in which case it will depend on how close they are to each other, how advanced their interstellar travel is, and/or how one defines "meaningful conversation".)

The difference is about 30 times, not "several hundreds". And by the way, what plants need is CO2. The Martian atmosphere is 95% CO2, whereas the air on Earth only has about 0.3% of CO2. That makes the partial pressure of CO2 ten times higher on the bottom of Hellas Planita than on top of Mount Everest!

The idealized likelihood of any one particular person is one in 64 trillion different genetic combinations of mother and father chromosomes. And with 100 billion neurons being stimulated throughout childhood, how are we to say that birth order influences one particular variable that we measure with various psychology tests? There is an immense amount of complexity that we cannot yet isolate (ask the neuroscientists), even in estimating the likelihood of specific combinations of genes because of diffusion gradients, energy interaction dynamics of DNA, and all sorts of other phenomena that keep us guessing only in 'Idealized' cases-- birth order is nowhere near such an idealization, however.

* Wikipedia linked me to this re: birth order and intelligence.
* Judith Harris on birth order and related psychology.

Space shuttles don't come anywhere near 11.2 km/s.

"Whats he imaging at 16000? Sounds a bit crusty to me."

I was going to say "MUD" - but your (apparently missed) joke is better.

Anyhoo - My first thought was "The ocean isn't that deep, is it?"

I found this on Google

I am actually saying multiple sources that are saying it is in the millions.

http://www.diycalculator.com/sp-cvision.shtml#A9b

http://hypertextbook.com/facts/2006/JenniferLeong. shtml

Am I missing something here? Maybe misreading or something, 350 000 just seemed really low.

Actually, while there seems to be differences in opinion, the lowest number I've found quoted is 100,000 and the highest is 10 million:

http://hypertextbook.com/facts/2006/JenniferLeong. shtml

http://hypertextbook.com/facts/2006/JenniferLeong. shtml

http://www.google.com/search?hl=en&q=1500+Cal+per+ hour+in+watts&btnG=Search

You, sir, are an athletic God (hint, that's 2.4 horsepower).

http://hypertextbook.com/physics/mechanics/power/

Armstrong can ride up the mountains in France generating about 500 watts of power for 20 minutes, something a typical 25-year-old could do for only 30 seconds. A professional hockey player might last three minutes - and then throw up....

Simple. At the distances involved in space battles, a laser has the problem of targeting. Since it can take several seconds to reach the target, the enemy ship can use random manuevers to prevent the enemy targeting system from getting a solid lock. Missiles don't have this problem as they can update their course to match the movements of the enemy vessel. That makes them much more likely to hit.

Lasers also have the problem of being far too focused. Assuming you actually got close enough to an enemy to make it an effective weapon (something they tend to gloss over in the series, but we can assume based on some scenes that they occassionally jump in pretty close), a laser will tend to cut surgically rather than doing collateral damage. The problem is that you want collateral damage in these sorts of weapons. Making a 1 inch hole in the vessel isn't very useful unless you can hit a key area. (Such as a magazine.)

The problem with hitting a key area is that you're talking about incredibly precise targeting. In a pitched battle, it can be difficult to get that targeting data. Heck, it would be hard enough to get yourself oriented after a jump, much less probe the exact pitch, angle, and cross-section of the enemy to compute the correct firing solution. (And that's assuming you know the internal layout of the enemy vessel.)

Not to mention that an enemy that knows you're using laser weapons is likely to deploy countermeasures. Such countermeasures can include building prisms into key areas to dissapate the energy into less critical sections (though the prisms would probably be destroyed after each use), launching smoke weapons between you and your enemy to confuse targeting and force some loss of beam coherence, and building flash-steam pools near the skin of the ship. (If you read Footfall sometime, the characters used water flowing through the skin of the Orion to absorb the heat from laser weapons. The water would immediately flash into steam, requiring a fast circulation system AND the ship to spin on its axis to prevent any one side from being exposed for too long. I have confirmed with physicists that this solution is a workable, though not perfect, solution.)

Lastly, lasers require a great deal of power. You'd need to build a large number of nuclear reactors into a ship to have any hope of charging the laser weapons quickly. For example, a 5 terajoule pulse (1 terawatt for 5 seconds) would take a 1 GW reactor 1.3 hours to charge. Such lasers do exist and are being used for fusion research. However, they are not robust enough for warfare and would burn out quite easily. Maintenance would be extremely high.

In comparison, a small nuclear missile would pack an order of magnitude more power than we are discussing with a laser weapon. Larger hydrogen weapons would be capable of several orders of magnitude more power. Nuclear missiles can update their trajectory based on sensor data from both the missile itself and telemetry from the parent vessel. Nuclear missiles are also quite effective at collateral damage, making them much more useful for hammering an enemy. While the nature of space combat means that a great deal of that energy would not directly impact the vessel (no atmosphere to carry a shockwave), it would still be far more effective than a laser strike.

I hope that answers your question?

For anyone interested, the figures in the paper show clearly the structuring of water in layers near the surface. Moreover they directly measure that the viscosity jumps up considerably for distances less than 2 nm. The viscosity goes from the bulk water value (9E-4 Pa*s) when far from the surface, and increases to as high as 50 Pa*s (500 Poise or 50,000 cP) in the last 0.5 nm. To give you an rough idea of what this means, note that 50,000 cP is similar to the (bulk) viscosity of things like honey or ketchup (for a random table of values, see here or here).

Of course this higher-viscosity persists only over a very short-range, but understanding these "nano-mechanical" properties is crucial for the design and construction of future nano-scale devices.

I was curious exactly what you'd have to do to get 1,000 Gs, so here are some back-of-the-envelope numbers for comparison:

It wouldn't survive being fired out of a handgun (zero to 800fps along a 5" barrel [1] implies an acceleration, assuming I did my math right, of ~468000 m/s^2 or about ~47,000 Gs).

Still, it's better than your brain inside your head, which can only take about 150-200 Gs before you start doing serious/irreparable damage [2] (the rest of your body is a lot lower, like 8-20 Gs depending on direction and body part, but your head alone can take a bit more since it doesn't have all those squishy bits).

I was curious how fast you'd need to be going in a typical car accident to get 1,000Gs: The fatal accident that killed Princess Di was supposedly somewhere around 70-100 G [3]; if we assume that was the result of crashing at 120 MPH or so, 190 km/h [4], we can extrapolate that to get 1,000G, you'd need to have a speed of around 1682 MPH. [5] (That doesn't say anything really about surviving a car crash at that speed, because obviously there are mechanical and thermal problems involved...)

So if you swallowed one of those things, I think it's pretty clear that you'd be mush long before it got bothered.

[1] Pulling these numbers out of my ass, but they're roughly typical for a 1911.
[2] http://hypertextbook.com/physics/mechanics/acceler ation/ referencing medical literature from helmeted motorcycle crashes
[3] ibid.
[4] http://en.wikipedia.org/wiki/Death_of_Diana,_Princ ess_of_Wales
[5] You use the acceleration value and speed to calculate a "time" for the collision, around 0.07s, and then use that to get the velocity for an acceleration of 1000G. I never said it was that reliable a figure...

Brain is central chemoreceptors. There are also peripheral chemoreceptors which are sensitive to O2.

http://en.wikipedia.org/wiki/Peripheral_chemorecep tor for a very basic stub summary

http://jap.physiology.org/cgi/content/full/96/1/35 9 for a slightly more in depth analysis of O2 as a breathing stimulus.

Now, at 12 000 feet pO2 is only about 60 mm Hg. This is less than half the distance to the top of Mount Everest. The highest human habitation occurs at about 20,000 feet where the pO2 is in the low 50s. I don't expect non-acclimatised people to go for a jog up there but we're not going to need close to that low levels here. References here: http://hypertextbook.com/facts/2005/MoniqueAnthony .shtml.

At sea level, 21% O2 gives pO2 of 21/100 x 760=159 mm Hg
This gives 18% O2 -> 18/100 x 760 = 136 mm Hg; 15% O2 gives 114 mm Hg; 10% O2 gives 76 mm Hg.

Lactic acidosis will occur with inadequate tissue oxygenation, but minute ventilation would be increased by peripheral chemoreceptor stimulation.

A summary of the physiology can be found at http://www.lib.mcg.edu/edu/eshuphysio/program/sect ion4/4ch7/s4ch7_27.htm (you may have to read a few pages).

So, to sum up: the low oxygen levels would be detected and the body would adjust ventilation accordingly. Levels of )2 lower than 10% are certainly compatible with life.

I would have preferred if everyone would have just taken my word for it originally rather than argue, but I suppose this is slashdot...

• 10 meter depth over 100% of planet surface
  
• 15 meter depth over 75% of planet surface
  
• 20 meter depth over 50% of planet surface
  
• 40 meter depth over 25% of planet surface
  
• 80 meter depth over 12.5% of planet surface
  

That seems reasonable enough, though my definition list included binary planets vs. a planet/moon system. If the center of rotation is INSIDE one of the objects, the other object is a moon, if not, a binary planet.

The variance needed should be around a percentage point. Generally speaking, if it's massive enough to produce a significant atmosphere it's a planet.

For some comparitive purposes, the earth is 12,756.3 km in diameter. Mount Everest is about 8.3 km high, the Marianas Trench is 10.9 km deep. The difference is 19.2 km. This is a 0.15% difference, between the highest solid point and the lowest. Now, due to erosion factors the Earth is actually fairly low on the list. If you count liquid and gas, it'd shrink even more.

The diameter of Mars is 6,794 km, the highest point is 27km, the lowest point is 6 km. Difference is 33km, for a percentage of .49%

A 1% maximum average difference would probably be a good place to start, though you might want to put in a compensation for rotational bulge. What I mean by 'average' would be that we don't want to have to map a planet to the detail that we have earth and mars in order to declare whether it's a planet. I just wanted to point out that planets large enough are relatively uniform in their sphericality.

That seems reasonable enough, though my definition list included binary planets vs. a planet/moon system. If the center of rotation is INSIDE one of the objects, the other object is a moon, if not, a binary planet.

The variance needed should be around a percentage point. Generally speaking, if it's massive enough to produce a significant atmosphere it's a planet.

For some comparitive purposes, the earth is 12,756.3 km in diameter. Mount Everest is about 8.3 km high, the Marianas Trench is 10.9 km deep. The difference is 19.2 km. This is a 0.15% difference, between the highest solid point and the lowest. Now, due to erosion factors the Earth is actually fairly low on the list. If you count liquid and gas, it'd shrink even more.

The diameter of Mars is 6,794 km, the highest point is 27km, the lowest point is 6 km. Difference is 33km, for a percentage of .49%

A 1% maximum average difference would probably be a good place to start, though you might want to put in a compensation for rotational bulge. What I mean by 'average' would be that we don't want to have to map a planet to the detail that we have earth and mars in order to declare whether it's a planet. I just wanted to point out that planets large enough are relatively uniform in their sphericality.

How deep under Asia is this water? We've only been able to drill to 12,262m so far.

OK, this explanation may not be simple, but I'm putting it out here anyways because it includes factors that make an interesting story.

You need to read at least 1/2 way through that article to get to the interesting stuff, but it basically says that radio waves in the 250Hz range will misdirect the navigational function of bees. It talks about Russian bee studies and and the possibility of foul play by said Russians with mind control devices (250Hz also causes agitation in humans) and the like.

Though that explanation is satisfying to me I'm sure there are people out there that would instantly deem this a conspiracy theory and reject it out of hand. In order to thwart those attempts I'll include a second theory - 240Hz is a subharmonic of our 60Hz power system and as electrical consumption increases so do the electromagnetic fields produced by the system... i.e. we've reached the consumption point of overhead power transmission that generates enough EM to dislocate the bees.

If you'd like to keep bees you'll need a bigger Faraday cage.

Using your figures for the diameter of the earth, the coverage of the oceans, and the area of greenland, and an increase of exactly 7m (since 23ft is obviously a conversion from 7m):
initial radius: 6367.9375
radius with 7m increase: 6367.9445
volume of initial sphere: 1081645595127.8
volume of final sphere: 1081649162151.3
difference: 3567023.5
70% (for coverage of sphere that is water): 2496916.4
required ice thickness over greenland to generate increase: 1.15km

According to http://hypertextbook.com/facts/2000/EmmanuelleStJe an.shtml, the Greenland ice shelf is at least 1.5km thick.

He says that he expects the initial products to be about 500-700 Watt-Hours/kg. and to, potentially, go as high as 1200-1500 Watt-Hours/kg. in the distant future.

My understanding is that this thing is supposed to run off of Hydrogen. It'd almost have, to as many consumer electronics are run indoors and most other fuels I know about give off toxic fumes when used in combustion engines.

Hydrogen has an energy density of ~33.3 Watt-Hours/kg. ( http://hypertextbook.com/facts/2005/MichelleFung.s html/ )

Now, assuming that the weight of the turbine (~4mm square) and packaging is negligible, most of the weight is fuel. In that case, we are looking at an efficiency of 1.5% - 2.1% for the initial models and 3.6% - 4.5% for the extreme upper end of what this guy thinks is foreseeable with this technology. 1.5% - 4.5% efficiency? That's horrible! Remember, pure hydrogen doesn't exist naturally on this planet. You had to spend large amounts of energy in the first place to produce the hydrogen that will be stored in these batteries (how exactly they plan on storing it I don't know because even the best, present day, techniques leak like a sieve because of the extremely small size of the hydrogen molecule).

Don't get me wrong, I can see where people would want something like this. The potential energy density compared to the compact form factor would open up new possibilities for portable equipment. There in lies the problem. The instant gratification of this technology will be almost impossible to fight. If every piece of small electronics had this kind of power source, cell phones, PDAs, laptops, etc. would become leaps-and-bounds more powerful and, at the same time, would be consuming energy at, potential, an exponentially higher rate.

The only way I can see this not becoming ubiquitous is if some other technology, like batteries, beats it to that energy density level. I don't think that's likely to happen because, even at these miserable efficiency rates, liquid fuels still have a massive lead in energy density over even the most promising, potential, battery technology known.

I hope there is an error in my math. Another possibility is that, as is so often the case, the author of the article doesn't have a clue of what he's talking about and had warped the facts of the story. The fact that he has suggested the possibility of replacing full-sized power plants with massive arrays of these turbines gives me hope that that's the case. If any of you have a correction for my math, please let me know.

-GameMaster

Sorry to rain on your parade, but according to this page, the volume of blood in an elephant is: about 9.5% to 10% of body weight. Using this page to get an estimate of an elephant's mass, we learn that they are on average 5000kg. So they contain roughly 500 liters of blood.

We have to take into consideration that I used an estimate of 20 terabytes for the LoC, if we half the number, then we get the figure 13,000 LoCs per elephant, which is already closer to your estimations. If we furthermore use a lower figure of 3500kg for the weight of an elephant, and consider that it's blood volume is 9.5% of it's weight, that yields 3 500 * (9.5%) = 332.5 liters of blood.

Enter into google: ((332.5 liters) / (0.0191739611 liters))/2
(remember, we divide by two because your estimate was 10 terabytes per LoC, whereas my earlier results went with 20 terabytes) and the result is
((332.5 liters) / (0.0191739611 liters)) / 2 = 8 670.61319

In other words, I'd say we can fit between 8670 and 26,000 Libraries of Congress in an elephant. I guess your results fit within the margins of error: Elephantology (much less LibraryOfCongressology) is not an exact science.

Now, when this flywheel goes off its bearings it will have to release that energy into the soil around it, which will mean some form of crater of roughly the proportions I give above. Now consider that there will be homes nearby--well within 200 feet of the original flywheel--and when their flywheels are disrupted, they too will release their energy into their surroundings.

Now, I'll grant that all these calculations are extraordinarily rough, and fail to take into account most anything. Still, I'd be nervous having a physical storage device like a flywheel holding the energy equivalent of 8 metric tons of TNT; I'd be nervous with batteries holding that much energy, and they seem a lot more docile.

Try this: Gasoline is about $1/kg and hydrogen is ~$6/kg (source). However, hydrogen provides over 120 MJ/kg energy (source) whereas gasoline provides 43 MJ/kg energy (source: wiki gasoline). So for hydrogen to be cost-comparable to gasoline, gas needs to hit $5/gallon. Which is....get this. Europe. Today.

I know, the article probably only refers to visible light, but note that we've detected things as far away as 12 billion light years: http://hypertextbook.com/facts/1998/JiYoungLee.sht ml http://en.wikipedia.org/wiki/Quasars

The statistical argument against Ice-9 doesn't hold water (yuk-yuk) without knowing the number of possible permutations that can occur (and how long it takes to try a new one). If there are on the order of 10^45 molecules of water on the planet (16 grams is one mole, and according to this the mass of the oceans is on the order of 10^24 grams), but there are 10^4500 permutations, it's entirely conceivable that such an accident hasn't happened.

This is the same logic that dictates that no two snowflakes are identical.

Of course, this is not to say that I believe there is an Ice-9, but I don't like the argument against it.

So please, stop using that reference. She was injured because McDonalds kept their coffee at an unsafe temperature.

Complete BS. Here's one link, there's plenty of others for those who actually care about the facts, which say that coffee tastes best at precisely the temperature McDonalds used.

http://hypertextbook.com/facts/2003/DianaGendler.s html

See e.g. here: http://hypertextbook.com/facts/2000/GeorgeRyabov.s html

Yes, there's no doubt that humans will survive if the planet is (say) 10 degrees F hotter. There will be lots of species that won't however, and it will very costly even for us.

Okay, this is slashdot so everything is needs to be questioned.

You did say a standard 40ft shipping container FULL of concrete.

Concrete weighs on average, 150 lb/ft3 (2400 kg/m3), the volume of a standard 40ft shipping container is 2390 ft3 (67.7 m3). That container full of concrete would weigh in at 358500 lbs (162613 kg). That weight is not exactly something you can move around and drop off at random places.

According to this, a grain of sand can range from 0.30 mg to 13 mg. That's milligrams: 1/1,000ths of grams.

The quoted safe dose of Po-210 is 6.8 picograms, which is trillionths (1/1,000,000,000,000) of grams.

Without taking the differences of density between sand and Po-210 into account (quartz is 2.65, Po is over 9), that amount is in the order of one-billionth of a grain of sand.

If the ice on top of Greenland melted, the Earth's oceans would rise 6 to 7 meters

Oh dear, I read that too, in some pro-GW article in the Guardian. And if you do the math, or even estimate the result, you will realise it is pure bull.

The increase in volume of ice over the same amount of water is about 9%.
Approximate area of all oceans 105,000,000 square km
Area of ice in Greenland is is 1,755,637 square km

So average depth of ice on Greenland needed raise global sea level by 6 meters (without taking the increase in sea area into account):

105,000,000 / 1,755,637 * 0.006 * 1.09 = 266,953,106 km

Do I think we should reduce polution and find a way to stop using fossil fuels? Hell yeah.

Do I think that "the sky is falling!" eco-nutjobs are prepared to lie to promote their cause, and in the process unwittingly bring the whole eco movement into disrepute? Damn straight.

Average body temp appears to actally be closer to 98.2. The 98.6 figure comes from a rounding error in converting from celsius.

From Lena Wong
"I vaguely remember hearing that the oft-quoted healthy human body temperature of 98.6 degrees fahrenheit was a "factoid"-- a statement treated as factual that has, in fact, never been verified. I have sent students out in search of real research on this matter, but they have all come up negative. It is a surprisingly difficult assignment. Source after source faithfully states that the temperature of a healthy human body is 98.6 F or 37 C -- no exceptions, end of story. The table above hints at the "truth"of the matter.

The first systematic measurements of human body temperature were performed by the German physician Carl Wunderlich. In 1861 he measured the temperatures of one million healthy individuals (a sample size that seems too large to be believed). The average value was reported as 37 degrees celsius. When converted this value becomes 98.6 degreed fahrenheit. So what's the problem? Wunderlich's value has only two significant figures while the converted value has three. The last digit (the "point six" at the end) should be regarded with great suspicion. Wunderlich's converted value should really be stated as "ninety eight point something" if one is being honest.

In 1992 Mackowiak, Wasserman, and Levine measured the body temperatures of 65 men and 65 women and came up with a value of 36.8 C (98.2 F). You can do a statistical analysis of the data yourself. The numbers are available online at numerous websites including The Physics Factbook"