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If I start with 20 meters = 69 pixels, then 1 km = 1450 pixels, or 1 km^2 = 2.1 Mpx. Ignoring the oceans (since they no doubt have far worse resolution), the Earth has a land area of > 148 million km^2. That comes out to about 148 M * 2.1 M px = 310 Tpx. If the ocean were at a similar resolution, it'd be about 1 petapixel.

How do you deduce, using common sense, that one in a thousand planets could harbor life?

By knowing that the milkywa y(our galaxy) has 100 billion stars: http://hypertextbook.com/facts/2000/MarissaWager.s html

And the one wekn ow most about it has 3 planets and at least one moon with the chance of life (albeit we know meanwhile that Venus is to hot and likely has none, but only a small change during planet forming might have made Venus a paradise as well)


How do you deduce, using common sense, that one in a thousand planets that harbor life have 'significant life'? (Whatever that is.)

With 100 billion suns, you can choose any small number you like, liek e.g.: 0.000000000001 - 0.000000000001 (the last number we know for sure) to estimate the number of planets with life.


How do you deduce, using common sense, that a few in a thousand planets with 'significant life' have 'intelligent' life?

E.g. because most life is intelligent? Apes and dolphines, horses, elephants, dogs .... plenty of those animals are intelligent, even if they are not outragous smart. Or you simply use the same numerical approach like above: we know that 1 out of 100 billion suns harbours intelligent life ... common sense says: its far to unlikely to believe its the only one.

angel'o'sphere

Our galaxy is about 100,000 light years in diameter. Every galaxy that revolves around a supermassive black hole within 400 light-years of our own galaxy has been cataloged.

Given the size of our galaxy, just how many other galaxies are within 400 lightyears of us, AGN or not? Or am I just massively confused here?

It is very hard to make this estimate, particularly as many words reached English, for example, from Latin by way of Norman French. However, the result of a computerized survey of roughly 80,000 words in the old Shorter Oxford Dictionary (3rd edition) was published in Ordered Profusion by Thomas Finkenstaedt and Dieter Wolff (1973). They reckoned the proportions as follows:

        * Latin, including modern scientific and technical Latin: 28.24%
        * French, including Old French and early Anglo-French: 28.3%
        * Old and Middle English, Old Norse, and Dutch: 25%
        * Greek: 5.32%
        * No etymology given: 4.03%
        * Derived from proper names: 3.28%
        * All other languages contributed less than 1%
http://www.askoxford.com/asktheexperts/faq/abouten glish/proportion?view=uk

... while the thrust of a motionless emdrive is high, the faster the engine moves, the more the thrust falls. Shawyer now reckons the emdrive will be better suited to powering vehicles that hover rather than accelerate rapidly.

makes no difference to sea levels.

EVERY time this comes up I have to debunk this stuff.

Do you understand why things float in water? Because the mass of water they displace is equal to the mass of the thing floating.

So now you have very dense saltwater, and much less dense freshwater ice (do you understand why ice is freshwater? It forces the salt out as the surface freezes, so the saltwater below it is even saltier and denser) If you have 1kg of ice, it displaces 1kg of saltwater. Simple enough right? Now let's hit it with the math.

Density of fresh water at 0C: 999.9 kg/m^3
Density of ice at 0C: 915.0 kg/m^3
Density of Ocean: We'll take 1020kg/m^3, the minimum on the site, even though at the pole due to the salt concentration noted in the first link the density of the saltwater will be way higher, but any density over 999.9kg/m^3 means that the water level shall rise as I show below:

1 cubic meter of ice (915.0 kg) displaces 915.0kg of saltwater. 915.0kg of saltwater is 0.897m^3 (915kg/(1020kg/m^3)), which means that our 1m^3 of ice has .103m^3 above the surface of the water (so says the old sailor's adage of icebergs being 9/10ths below water).

Now, let's say the ice were to suddenly vanish. There would be a "hole" in the ocean with 0.897m^3 of air in it. Water would of course rush into the "hole" and the water level would drop by 0.897m^3 spread out over the entire surface of the ocean.

But let's say the ice were to melt. Our 915kg of ice would become 915kg of fresh water, which would occupy about 0.915m^3 (915kg/(999.9kg/m^3)). The hole the ice occupied previously was only 0.897m^3 large, which leaves us with .018m^3 more water than we began with. This .018m^3 would spread out over the surface of the ocean, raising the water level ever so slightly. (sorry, your "no difference" myth has just been busted.)

Don't forget that this tiny amount will be joined by water running off of Greenland, Antartica and other polar landmasses with ice on them, 100% of which will raise the water level.

CDs have a hard limit for frequency response, with an immediate cutoff at 22050hz, whereas vinyl's frequency response extends past 25000hz with a very gradual rolloff

I realize you were making a joke, but I just thought I'd point out that what I was trying to get at in my original post, is that it's impractical to carry around as much energy stored electrochemically in batteries, as you can store in the form of combustible hydrocarbons.

So if your battery runs out, it's probably not practical for you to just keep shoving new batteries in it for very long, because the energy density just isn't there. You would probably have a tough time carrying the battery equivalent of a few liters of methanol or LPG.

A person could easily carry around enough butane or methanol to keep a computer running for a long time; thus a wall socket is not necessary. And although you jest, although I've never seen a butane socket, natural gas lines are widely available in urban areas (although if you want to store it, you'd need liquefaction apparatus), and ethanol retail outlets aren't hard to find in most areas either. (Actually, in my area, they're already run by the government...)

Just for reference, the energy density of methanol is around 22 MJ/kg [1], while a good LiIon battery is around 150 Wh/kg [2], or around 540 kJ/kg; that's a difference of over 40x. So you could stray a lot further from existing infrastructure with a "portable" device powered by methanol than you could on batteries.

[1] http://hypertextbook.com/facts/2005/JennyHua.shtml (this is for methanol in a fuel cell, its thermal energy density is probably higher)
[2] http://en.wikipedia.org/wiki/Lithium-ion_battery

I can still pick out frequencies at and around 40Khz

Lumpy, you're full of shit. You couldn't have just exaggerated; you had to give yourself double the accepted range of human hearing...

well the article is so short its not possible to comment on their implementation. so here are some calculations i did to amuse myself.

number of neurons in the brain: 100 billion
http://hypertextbook.com/facts/2002/AniciaNdabahal iye2.shtml

transistor count per CPU: ~300 million
http://www.anandtech.com/cpuchipsets/showdoc.aspx? i=2795

average synaptic connections per neuron: 7000
http://en.wikipedia.org/wiki/Neuron

total number of synapses: 100 to 500 trillion

since a 'calculation' for one artificial neuron mostly involves a summation of weights, we can view one total step as 2 X the number of synapses we wish to analyze. or 200 - 1000 trillion calculations for one step. by step i mean summing all inputs and pushing the result to an output for each neuron.
http://en.wikipedia.org/wiki/Artificial_neuron

fastest computer in the world FLOPs: 280 trillion
http://en.wikipedia.org/wiki/Blue_Gene

pentium 4 FLOPs: 40 GFLOP

using the fastest computer in the world 1 step would only take around 1 - 5 seconds, not counting storing all of that information.
http://en.wikipedia.org/wiki/Blue_Gene

so how fast do we think? well i couldn't find anything on this so lets get a quick estimate. the average neuron is .1m in length .1 / c = 3.3x10^-10 or 333 picoseconds. now lets add in some delay for the chemicals in the neurons to do their thing, this is probably much slower than the electrical impulse, so lets say 3.3 nanoseconds.

so assuming our computers could network instantly, and store the data used instantly, we would need 3-15 trillion Blue Gene supercomputers to simulate the human brain in real time. or if we are using pentium 4s we would only need 21-105 trillion pentium 4s.

man thats a lot of cpus.

number of computers in the world: ~300 million
http://www.aneki.com/computers.html
guess at average FLOPs per computer: 40 GFLOPs
total FLOPs of worlds personal computers: 1.2 PFLOPs
time to calculate one brain step if all computers in the world were networked: .2 - .8 seconds

using moores law, when will a single computer be fast enough to simulate the human brain in real time?
200-1000 trillion calculations per step = ~600 trillion every 3.3ns = 181x10^18 or 181exeFLOPs
181exaFLOPS / 40GFLOPS = 2^n, n=32
32*18mo = 48 years based on personal computer technology

or 28 years based on supercomputer technology

of course a real neural network will contain highly parallel processing and using a specific chip design we will probably be able to simulate a brain much sooner, perhaps in the order of 10-20 years.

...but granite is so thermally conductive, it's feeling very cold and keeping that way for hours.

Well, over at the usual place, I found some values for the specific energy (potential chemical energy per unit mass) in a variety of fuels. A better source would probably be the CRC Handbook of Chemistry and Physics, but I left it in my other coat today.

Gasoline is quoted at being around 44 megajoules per kilogram. (More sources here.)

Under ideal conditions, neglecting irreversible losses like wind and rolling resistance, you'd only have to burn fuel when you wanted to change your vehicle's speed -- because without friction it would just roll along all day -- and the energy required is a pretty trivial Newtonian mechanics problem. The work to accelerate it is just (1/2)mv^2, where m is the mass and v is the velocity. Then of course you add the 'real work' to change its position: going uphill 'costs' you mgh, where g is acceleration due to gravity and h is the height upwards moved.

If you had a perfect regenerative braking system, then theoretically you'd never need to use any more gas at all (except when going to a higher altitude then you'd gone before); you'd just stop using the regenerative brakes, then turn that energy right back out and use it to start moving again. Without regenerative brakes, you just waste the input energy whenever you stop (except whatever energy you've stored by virtue of the car's position, i.e. by parking it at the top of a hill).

Of course in real life that doesn't happen: the regenerative brakes are going to have losses, there's non-trivial rolling resistance and wind resistance that grows (I think) proportionally to the square of your forward speed.

I'm not going to go through all the math right now, but basically it's a very simple problem that boils down to what simplifying assumptions you want to make. If you add in rolling resistance and aerodynamic drag and make realistic assumptions about the brakes and transmission, at a certain point all you're asking is "what is the fuel economy of an average car, if it had a perfectly efficient engine?" If that's the question, there are easier ways to solve it: you can just figure out the "thermal efficiency" of an internal-combustion engine (not hard: put an engine on a dyno and measure the energy output at the same time as you're measuring the fuel going in) and calculate what the fuel consumption would have been, if it were 100% efficient.

The accepted figure for thermal efficiency of an ICE seems to be around 25-26%, so the short answer is that if the engine in your car right now was a perfect converter of the energy stored in gasoline to mechanical movement, you'd get around four times the gas mileage that you do right now.

Using the lower number gives us a distance of 2850 kilometers in 50 million years.

You mean the lower number that is the relative speed between two plates that are moving away from each other?

Read what you posted again:

South America and Africa are moving apart at an average of 5.7 cm per year

The implication is that South America is moving 2.85 cm west each year and Africa is moving 2.85 cm east each year.

Since you are dealing with the absolute speed of a single plate (not its relative speed to another), you could "get away" with 2.85 cm per year.

However, since we are talking about either North American plate or the Eurasian plate, you should use 1.15 cm/year or 0.95 cm/year. This would be a worst case of around 600 km.

- Tony

http://hypertextbook.com/facts/1998/StevenChen.sht ml

see here, the FIRST LINK I FOUND ON SPEED OF A BULLET for godsake do some of your own research. Slowest speed mentioned is 180 m/s which is just unbder 400 miles an hour. The plane had just finished a powerdive and was doing over 500 miles an hour. QED. ( I didnt say fast rifle bullet, but tell me, would you rather a glancing blow from a fast rifle bullet, say 1500 mph, or a 10 tonne titanium/steel lump at 500 mph?)

Sorry. You're wrong. I know you're an AC and so will never see this, and you were just trolling anyway, but:

Percent: 10.82

Volume: 2,600,000 km3

Percent: 7.9

Maximum sea level rise potential: 6.5 m

Area: 1,736,095 km2"

And if you don't believe Random-Website (I wouldn't), you can find the figure of 23 feet on Wikipedia, from Greenland alone. And if you don't trust that, you can do the math yourself. Volume of ice on Greenland: 2.6*10^6 km^3. Surface area of Earth's oceans: 360*10^6 km^2. Density of ice: ~.92 times that of water. So, (2.6*.92)/360=.0066 km. Or, 6.6 m rise. Or, ~22 feet.

According to this physics website, "Coal has a relatively high energy density of approximately 24 MJ/kg". Joules can also be expressed as "watts per second". A Pentium M (mobile) consumes 27 watts at peak utilization, and 5 watts at idle. So the would burn through that eight pound piece of coal in 10 seconds at idle, or two seconds under max load; backing up the television program's claim--if we forgot to account for the "M" in MJ/kg. Sounds like someone put a decimal point in the wrong place. That chunk of coal would actually power a Pentium M chip at full power for 23 days. (I'm ignoring things like the power consumption of the LCD, waste heat, etc. While not insignificant, those factors aren't going to affect the scale.)

The heat of combustion of coal is about 26 MJ/kg (see here). The overall efficiency of electric power generation for coal is about 35% (see here). Therefore, eight pounds of coal would produce about 28 MJ of electricity. If a laptop uses, say, 50 W maximum, that eight-pound lump of coal could power a laptop under maximum load for about 158 hours, or about 6.5 days. That's a lot of power.

The specific heat of steel is 452 joules per kilogram per degree C.

The melting temperature of steel is 1370 degrees C (room temperature is 20 degrees), so the the lightsaber has to raise the temperature 1370-20=1350 degrees C).

Now (to pull some numbers out of my ass) let's say our hypothetical jedi swings a 1-meter-long-and-.02-meter-wide lightsaber through a bulkhead in a circular fashion, sweeping out a 120 degree arc. The volume of steel he has to melt is (120/360) * (pi*r^2) *width, where r = 1 meter and width = .02 meters -- 0.0209 cubic meters of steel.

The average density of steel" is 7.85 grams/cubic centimeter. According to google calculator, 1 gram per cubic centimeter equals 1000 kilograms per cubic meter; therefore, 7.85 grams/cubic centimeter = 7850 kilograms/cubic meter.

Thus: the lightsaber must melt (7850 kilograms/cubic meter) * (0.0209 cubic meters) = 164.065 kilograms of steel. This will require (164.065 kilograms) * (452 joules per kilogram per degree C. ) * (1350) = 100112463 joules of energy. QED.

Mars ~ 1/100 of earth atmosphere at sea level and mainly CO2
Moon pressure (none or nearly none)

Less harsh is a kind of misnomer. You would probably have the same kind of problem between a wall separating 1 atm air and 1/100 atm CO2, as with a wall separating 1 atm air and 0, nada...

You can only heat your house once, and it gets REALLY hot.

A few floors collapsed, yes. But the bulidings did not. The force of a floor falling on the floor beneath it should not generally be enough to bring the lower floor down.
One floor falling on a lower floor, perhaps. But what about scores of floors? Each floor that collapses would produce additional momentum. There's also the damage caused from the jetliner to consider here for WTC1 and 2, or the falling debris on WTC7.
See this well done presentation.

Think about it: the floors have been holding that weight up for decades.
That's a statement about mostly statics that is meaningless for this argument. They held up floors for decades, but without the dynamics of significant structural damage, fire, etc.

A jet fuel fire is no hotter than any other hydrocarbon fire that reaches it's maximum possible temperature.

Under ideal lab conditions, sure -- but we're comparing something that intended to ignite and burn (fuel) with a random assortment of office equipment that would likely include fire retardants in the carpet, wiring, etc. These are things that are not intended to ignite, let alone burn for long periods of time.
Can you provide evidence that any of those previous building fires burned at the same temperature and for the same amount of time as a large jet fuel fire?
And even if they did, there's still the pesky problem of the massive amount of variables involved in each of these cases. I'll say it again, just because it didn't manage to fully collapse in a handful of previous cases involving different buildings and far different conditions, doesn't mean it is impossible or even unlikely.

There's simply no way the jet fuel was still burning weeks later when they were still finding pools of molten metal.
Assuming a few eyewitness accounts of pools of molten metal are true, what melted them? And what kept them in a liquid state for these eyewitnesses? Planted explosive charges in the basement? Seems like that would have cooled off quickly.
Was steel the only metal at WTC? What about Aluminum, yaknow, from the planes? Al melts at ~1200F. Can these eyewitnesses visually tell different pools of molten metal apart?
Or couldn't they have meant melted steel?
Or perhaps it was glass. Some glass melts as low as 900F.
And where are the pictures of the molten metal?

The steel didn't need to melt for the towers to collapse. I'm sure you've seen it, but here's the link to the Scientific American debunking anyway.

Extraordinary claims require extraordinary proof. And so far, the "official" version of events has far better evidence.

and the People http://www.ibiblio.org/lunarbin/worldpop we find that it's .02 km sq per person.

and thats weird...

Happily, this system produces 1/3 to 1/4 the acceleration of an average car.

:D

BTW, I juxtaposing the lab gas with nuke heat:

Nuclear Weapon Thermal Effects:

Special Weapons Primer; Weapons of Mass Destruction:

http://www.fas.org/nuke/intro/nuke/thermal.htm
-----------

Temperature of a Nuclear Explosion:

The Physics Factbook
  Edited by Glenn Elert -- Written by his students
  An educational, Fair Use website

http://hypertextbook.com/facts/1999/SimonFung.shtm l

----------
Nuclear Weapons Effects--An Overview

  by Wm. Robert Johnston
  last updated 8 March 2005
http://www.johnstonsarchive.net/nuclear/effectsum. html

Bon-therma-tit...

Before pulling figures out of your arse, perhaps you should take into account the following:

- The population of the USA is less than 300m (if you were refering to the whole continent you should be more clear.)
- A household in most cases comprises of more than 1 person, so 1 car per household does not equal one car per person.
- Children and some adults can't drive, yet they are still included in the population figure.
- A saturated market only means that everyone who would buy a product owns it, not that everyone actually does, as not everyone will want said product.
- Parts of Eastern Europe are quite poor so it is doubtful that the market is saturated there, yet you included the popluation for the whole of Europe in your figures.

There are probably other points that should be taken into consideration, but I'll leave you with this, I did actually try to verify that 750 million figure myself and although I couldn't find a link for it, I find find a source from 2001 that states there are 600 million cars in use, so 750 million today seems plausible, but your figure certainly is not.

because of the properties of ICE vs Liquid Water the melting of the Artic ice sheet actually lowers water world wide..

Errr... WHAT?

Time to do the math again, I guess. Every now and then this bit of ugly science rears its ugly head.

Useful numbers:
Density of Seawater: 1025kg/m^3.
Density of Freshwater: 1000kg/m^3 (rounded up from 999.98 at freezing point)
Density of Ice: 916kg/m^3 [same source].

Things to know:
The vast majority of icebergs are not frozen seawater, they break off from land glaciers and float out to sea.
Buoyancy tells us that X will float in Y if X displaces a volume of Y where the mass of the displaced volume equals the mass of X.
Hollowed out shapes can contain more volume than a solid block of mass (this is why metal boats float).

So, lets say we have a solid, convex iceberg floating in an ocean ever so slightly above freezing, consisting of exactly 1025kg of ice right about to melt. To float, this iceberg must displace 1025kg of saltwater, which by sheer coincidence is exactly one cubic meter. Thus, when this iceberg broke off the glacier and fell into the water, the sea level increased by the height of one cubic meter spread out really thin across the entire surface. If you lifted the iceberg out without letting it melt, that one cubic meter would come back and fill the hole where it was.

Naturally, the sea being ever so slightly above freezing and the ice being ever so slightly below, the ice absorbs heat from the ocean and melts. Thanks to wonderful conservation of mass, we know we now have 1025kg of fresh water at ever so slightly above freezing, with a density of 1000kg/m^3. Thus, we have 1.025 cubic meters of fresh water to fill that 1 cubic meter hole where the iceberg used to be.

So because the iceberg fell into the ocean and melted, the sea level is now 1.025 cubic meters (spread out real thin over the entire ocean) higher than it used to be. Even if the ice started in the ocean (as in the Arctic), it's still 0.025 cubic meters high! It gets worse if the ice is sitting on the bottom of the ocean (then there is more ice than displaced water)! Even if you assume that the seawater is less dense in the Arctic (a fallacy, as the freezing action actually increases the saline content of the water around the ice), as long as the density of the seawater is greater than the density of the water you get from melting the ice (almost always freshwater), you will get an increase in sea level from melting the ice.

Incidentially, arctic ice is not all frozen seawater, much of it is from precipitation falling on top of the frozen seawater, so you can't even claim that the water in the ice came directly from the ocean in the first place (not that that claim would really help any, because that water has been locked up for thousands and thousands of years, returning it to water would definitely raise the ocean level beyond anything in written history). Plus, once the water is liquid and continues to heat, it will continue to expand: at 30C freshwater is only 995.65kg/m^3.

Since I whipped out the math anyway, 1025kg of ice is 1025kg*(1m^3/916kg)=1.119 m^3. Since it's solid and convex we know that there must be 0.119 m^3 of ice above sea level. This shows that roughly 10% of the 1.119 m^3 of ice is above sea level, thereby supporting the old adage that 9/10 of the iceberg is below the waterline.

because of the properties of ICE vs Liquid Water the melting of the Artic ice sheet actually lowers water world wide..

Errr... WHAT?

Time to do the math again, I guess. Every now and then this bit of ugly science rears its ugly head.

Useful numbers:
Density of Seawater: 1025kg/m^3.
Density of Freshwater: 1000kg/m^3 (rounded up from 999.98 at freezing point)
Density of Ice: 916kg/m^3 [same source].

Things to know:
The vast majority of icebergs are not frozen seawater, they break off from land glaciers and float out to sea.
Buoyancy tells us that X will float in Y if X displaces a volume of Y where the mass of the displaced volume equals the mass of X.
Hollowed out shapes can contain more volume than a solid block of mass (this is why metal boats float).

So, lets say we have a solid, convex iceberg floating in an ocean ever so slightly above freezing, consisting of exactly 1025kg of ice right about to melt. To float, this iceberg must displace 1025kg of saltwater, which by sheer coincidence is exactly one cubic meter. Thus, when this iceberg broke off the glacier and fell into the water, the sea level increased by the height of one cubic meter spread out really thin across the entire surface. If you lifted the iceberg out without letting it melt, that one cubic meter would come back and fill the hole where it was.

Naturally, the sea being ever so slightly above freezing and the ice being ever so slightly below, the ice absorbs heat from the ocean and melts. Thanks to wonderful conservation of mass, we know we now have 1025kg of fresh water at ever so slightly above freezing, with a density of 1000kg/m^3. Thus, we have 1.025 cubic meters of fresh water to fill that 1 cubic meter hole where the iceberg used to be.

So because the iceberg fell into the ocean and melted, the sea level is now 1.025 cubic meters (spread out real thin over the entire ocean) higher than it used to be. Even if the ice started in the ocean (as in the Arctic), it's still 0.025 cubic meters high! It gets worse if the ice is sitting on the bottom of the ocean (then there is more ice than displaced water)! Even if you assume that the seawater is less dense in the Arctic (a fallacy, as the freezing action actually increases the saline content of the water around the ice), as long as the density of the seawater is greater than the density of the water you get from melting the ice (almost always freshwater), you will get an increase in sea level from melting the ice.

Incidentially, arctic ice is not all frozen seawater, much of it is from precipitation falling on top of the frozen seawater, so you can't even claim that the water in the ice came directly from the ocean in the first place (not that that claim would really help any, because that water has been locked up for thousands and thousands of years, returning it to water would definitely raise the ocean level beyond anything in written history). Plus, once the water is liquid and continues to heat, it will continue to expand: at 30C freshwater is only 995.65kg/m^3.

Since I whipped out the math anyway, 1025kg of ice is 1025kg*(1m^3/916kg)=1.119 m^3. Since it's solid and convex we know that there must be 0.119 m^3 of ice above sea level. This shows that roughly 10% of the 1.119 m^3 of ice is above sea level, thereby supporting the old adage that 9/10 of the iceberg is below the waterline.

dung, air dry 12.0 MJ/kg (compare to 45.8 for automotive gasoline).

http://hypertextbook.com/physics/matter/energy-che mical/

Random fact: French has about 100,000 words. English has about 616,500 according to the Oxford English Dictionary. Many estimate put it much higher.

Source: http://hypertextbook.com/facts/2001/JohnnyLing.sht ml

The density of interstellar space is about one atom per cubic centimeter. If the spaceship were going near the speed of light (3 x 10^10 cm/sec), it would be hit by 3 x 10^10 relativistic particles per cm^2/sec. This is about the equivalent of one Curie per cm^2, which would kill a human and cripple any electronics on board

A very heavy magnet could deflect the protons, but the neutral atoms would be unaffected by the magnetic field.

http://hypertextbook.com/facts/2003/ChrisDAmbrose. shtml

Human hearing typically extends up to 18 - 20 KHz for young people, less the older you get. So 44 KHz (22 KHz Nyquist frequency) gives a decent safety margin. 16-bits is quite a bit finer than people's senses can reasonably register as far as intensity goes, certainly for light and I suspect for sound as well, particularly in an environment with noise (and every environment has some noise).

The story is different if you want to manipulate the signal somehow. In that case you need some margin, thus 24-bits with a sampling rate of 96 KHz. It's also why I shoot 12-bit digital photos, print film has an excess of dynamic range and medical scanners acquire 12 or 16-bit images. You can't actually SEE all that range -- it has to be compressed into more like 8 or 9 bits, but you have some flexibility in doing that. For photos you can adjust the exposure and white balance, for a CT exam you can look at bone or soft tissue.

For listening purposes, the music companies giving us 44 KHz 16-bit music is all you'll ever need, although they'd desperately like us to think that even higher quality is worth (re)buying. I guess if you're going to remix it, maybe.

These form a ball of plasma about 300 times hotter than the surface of the Sun.

According to The Physics Factbook the temperature of the surface of the sun is approximately 6000 C. (I am assuming that it is the photosphere temperature that is ment here.) A temperature 300 times higher would be about 1.8 million C which is an order of magnitude less than the temperature at the center of the sun (~15 million C). I would have thought that these collions would have resulted in temperatures much higher than that.

Does anyone have a better reference for the effective temperature involved?

These form a ball of plasma about 300 times hotter than the surface of the Sun.

According to The Physics Factbook the temperature of the surface of the sun is approximately 6000 C. (I am assuming that it is the photosphere temperature that is ment here.) A temperature 300 times higher would be about 1.8 million C which is an order of magnitude less than the temperature at the center of the sun (~15 million C). I would have thought that these collions would have resulted in temperatures much higher than that.

Does anyone have a better reference for the effective temperature involved?

Ok, so we're already screwing up the ecological system of one planet, so all the more reason to start mining the moon too!

Ecological system? On the moon? Dude, give me some of what you're smoking, I need it to get the moon.

Oh, sure, the moon is 1/5th it's original size now in due to all the mining, but you can still find it with a telescope in the night sky.

1. The moon is approximately 7.475 x 10^22 kg in size, or approximately . We haven't even dug up the equivalent of 4/5ths of the moon in the entire time we've been on Earth!

2. The moon is mostly composed of oxidized Iron. a.k.a. Rust. It might make a great base for various space operations (e.g. manufacturing, staging, telescopes, power collections, etc.) as well as a proving ground for our upcoming launch technologies, but there are far better places in the Solar System to be mining. You know, like all those heavy metal rich asteriods that pass by Earth all the time.

No reason to think that a larger animal has a larger brain... elephants and whales still have smaller brains than ours.

I'm not sure where you got that idea, but it's incorrect. Elphants and whales have much larger brains than we do. You're probably thinking of the ratio of brain size to body size. That's where humans "win" (and it strikes me as a "...best 2 out of 3?"-type face-saving attempt), with much larger ratios of brain mass to total body mass than the aforementioned animals. However, we are beaten there by other animals... such as mice. Also a Bottlenose Dolphin will beat a morbidly obese human, who has much more body mass but no more brain mass.

http://hypertextbook.com/facts/2003/RachelScottRos enbluth.shtml

http://hypertextbook.com/facts/2003/AdamCassino.sh tml

The TOP 100m dash speed is about 10 meters per second or 22 miles per hour, and 90% of those guys are nowhere near that fast.

Perhaps. I'm aware there's some controversy over the timings of 40 yard dashes for NFL players. OTOH, the track records are timed from the gun, not from first movement, so 100m records carry about 0.1-0.15 seconds penalty... the amount of time it takes the runners to react to the sound of the gun. Adjusting for that adds 1-2mph to the average speeds, and you also have to remember that the top speed is higher than the average speed. This gives a highest-ever instantaneous velocity of 12.1 m/s, or 27 mph. Granted that even the best football players are slower than these world class sprinters, they're still very fast. Probably not much over 20 mph, though.

I'll grant your point on combining two players speeds together in opposite directions, but that wasn't the implication of the original statement.

No?

Two masses that size colliding at 10, 20 , or 30 miles an hour

Seems exactly the implication to me.

Assuming earth-sized solar panels won't be in the picture anytime soon, I think it would be safe to say that even billions of solar panels won't be enough to block the sun's rays, because the sun is so massive and its light is extending everywhere. The shadow produced from one of these solar catchers would be like that of a gnat flying just over your head--you wouldn't even notice.

I also doubt said panels would have any effect on alien worlds, since those worlds would have their own star / energy source--why would they need light from ours?

http://hypertextbook.com/facts/2001/StaverieBoundo uris.shtml states the SRBs providing about 71% of the thrust during take off and first stage ascent. The first stage burns the most amount of fuel as it has to do more work than subsequent stages.

And the whole point of using SRBs is because H2/O2 isn't a cheaper alternative. H2/O2 may be more efficient in terms of raw energy released per unit mass, but that doesn't actually translate to a more efficient rocket. You have to take into account extra things such as the mass from the engines, storage (cryogenics adds a lot of weight), pipes, nozzles, valves, computers (redundancy on these), etc. Whereas the SRBs have a lot less extra mass and therefore provide a better punch. It's a bit like comparing a cheap firework and a model plane,the firework trades control for power, and when a typical launch costs $300 million, the firework model looks like a big bonus for a CEO.

If you google the phrase "temperature of coffee", you'll find dozens upon dozens of sites (unrelated to the McDonald's case) recommending what temperature coffee should be brewed at. Here's one example: http://hypertextbook.com/facts/2003/DianaGendler.s html. Here's a study on what temperature people prefer their coffee: http://ift.confex.com/ift/99annual/techprogram/abs tracts/3583.htm.

The range that McDonald's brewed its coffee at is right about at the range most people recommend, and only slightly hotter than the average temperature people prefer to drink it.

And someone is looking for ideas to blame this on the USA. The 1985 James Bond flick A View to a Kill came up with this idea of pumping water from a lake into a fault (with a Nuke - obsession of most Bond villains with Nukes) elsewhere close to the San Diego fault to destroy Silicon Valley. There is a little scientific salt in this idea, pumping fluid (although not in small quantities) into an existing fault could initiate seismic activity. Now someone says a single sky scraper can do this with just 700,000 tonnes. Other than becoming an idea for some B-grade movie, I don't see any useful implication here. The global weather cycle is interesting, El Nino seems to be delivering lesser heat this year and there's lots more interesting changes happening. Indonesia for all the quakes has about 76 active volcanoes, the highest for a single nation. So no one was correlating recent seismic and volcanic activity with the point that Indonesia was on its way to attempt to construct the world's tallest building. Now some Taiwanese scientists have the luxury to think about tall buildings and link them to possible impending earthquakes. This is a wake up call for the real scientists, before these people start naming it the "Tower of Babel" effect. Scientific news in the media and magazines are really lacking. Popular Science reports in media is almost always a publicity stunt.

First off, avgas, kerosene or jet fuel have within a few percent (and it's usually actually a little bit *lower*) the same energy density as diesel. (Reference) Each of these fuels may have slightly different properties (different ignition temperatures and pressures, for example), but their energy density is really pretty close.

Second, energy is energy. You can convert (with some loss, of course) any form of energy into any other. So, you want true avgas? No problem: synthesize it using biodiesel. You need kerosene? Synthesize it. Or, tune your biodiesel-production system to produce kerosene instead.

It isn't difficult to imagine a dictionary attack working against a password of the form "concerned$citizen". There are roughly 1,000,000 words in the english language http://hypertextbook.com/facts/2001/JohnnyLing.sht ml. It wouldn't be difficult to transform each word by doing every permutation of common substitutions, e.g. s=>$ o=>0 e=>3 etc. I'm spectualating but for purposes of calculcations lets say that on average each word will have 20 such permutations. That gives us a total of roughly 20,000,000 possible words. In addition one could take it a step further and try all combinations of two such words, 20,000,000*20,000,000 = 4e14. In addition we may want to allow for arbitrary characters to be inserted between such words, 4e14 * 73 = 2.9e16, where 73 is 52 leters + 10 numbers + 10 punctuation + 1 blank.

Using your assumption of 2,000,000 hashes per second per machine. It would take 2.9e16 hashes / 2,000,000 hashs/(sec*node) / 60 sec/min / 60 min/hour = 4e6 node*hours

With a 1024 node cluster it would take 4e6 node*hours / 1024 nodes = 3906 hours = 163 days
To do it in 90 days would take 4e6 node*hours / 90 days / 24 hours/day = 1852 nodes.

I think these numbers demonstrate that it is definately within the realm of possibility for a well funded government agency to crack such passwords.

Glad to be of help .

I don't think anyone can own orbits much like noone on Earth can own the path they (or their car) made while moving from point A to point B .

Noone owns space since it is basically void plus I think it would fall under the Treaty since , I think , it refers to Outer Space in general .

If you are interested in astronomy check out also about the cosmic year (one solar orbit around the center of the Galaxy) http://hypertextbook.com/facts/2002/StacyLeong.sht ml/ttlx_new . I think that is also considered as Outer Space . The Universe with approximately 100,000,000,000 galaxies (according to scientists) in its 13-14 billion light years in length size (1 light year = 10 trillion kilometers app.) that the scientists have so far observed or calculated to exist is also considered as Outer Space .

Regarding the squatter's right ...
On Earth if someone possesses and occupies an area for a number of prescribed years , he can legally own that land (even public land) . That period is rather long , app. 20 years in most countries , during which no legal owner should claim the land , but after that the occupant can demand ownership documents to be issued to his name , legally . It does not apply to Outer Space under Article II of the Treaty ("Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means) .

Well then you are an idiot!

Focal lengths are measured in millimeters, even for the hubble. Anything beyond a couple thousand METERS is pretty much considered infinity.

I saw and studied to the HDFS you quoted - the focal difference between me and you vs. me and the furthest galaxy in that shot are negligable, from an optical point of view!

Aww right, I must be an idiot. Despite the focal length of the Hubble Space Telescope being over 50 meters . Whatever my friend. :)

Hypoxia is a "nice theory" to the same extent as gravity and evolution are "nice theories". This is a very well researched area, which you don't appear to know much about, so here are some links:

Maximum altitude of human habitation:
http://hypertextbook.com/facts/2005/MoniqueAnthony .shtml

Maximum altitude of human survival:
http://en.wikipedia.org/wiki/Death_zone

On the one in a billion who can make it to the top of Mt. Everest without supplimental oxygen:
http://en.wikipedia.org/wiki/Sherpa_Ang_Rita

I'd like to remind you that these numbers are for extremely fit, trained individuals. For your AVERAGE human being, like the ones who are presumably going to ride in this thing, the numbers are far less. But don't take my word for it, take the FAA's (Federal Aviation Administration) when they decided what minimum levels of oxygen should be supplied to air passengers, not to mention pilots:

For private flying:
http://www.airweb.faa.gov/Regulatory_and_Guidance_ Library/rgFAR.nsf/0/BA9AFBF96DBC56F0852566CF006798 F9?OpenDocument

For Part 121 Airline flying:
http://www.airweb.faa.gov/Regulatory_and_Guidance_ Library/rgFAR.nsf/0/38EA18D996EDBCEC86256F3C0069EB 60?OpenDocument

So, while it is possible, briefly, for extremely fit, acclimated individuals to survive at 15,000 foot plus altitudes, it is not something that you would want to go through just to ride on a bloody train. If you really want to learn more about Hypoxia, go to a local Air Force base, and they may give you a complementary ride in an altitude chamber. This is done with all military (and most civilian) pilots, so that they can learn what their personal symptoms of hypoxia are. They even videotape it - it's very entertaining to watch yourself drool and not remember it, and to see how a sentence you were to write at each 1000' pressure bump turns from neat penmanship into a seismograph.

I recently derived the famous equation in my slashdot journal entry. It can be found when starting from the assumptions Einstein had when Special Relativity was first proposed. That is:

• The laws of the universe are valid in all inertial reference frames.
• The strength of electric and magnetic fields are each a certain constant in space.

From the second axiom, you can show that the speed of light only depends on the strength of electric and magnetic fields in space using Maxwell's equations. An interesting derivation that requires vector calculus, so I'll save the pain of it for you. ;-) From the first axiom, you can show that the speed of light violated Galilean Relativity.

Knowing that Galilean Relativity is still useful, Einstein proposed another assumption:

• To fix Relativity you need only a simple linear correction factor.

From that, you can derive the Lorentz Transformations. Then while examining how those transformations affect the conservation of momentum in collisions you can derive a more useful definition of momentum based on the old definition and that correction factor.

Finally using the new equations of Momentum and the Lorentz Transformations, you can redo Young's derivation of Kinetic Energy using the old definitions of velocity, force, and energy. The end result is a mass at rest still has some energy. This energy is called the rest energy and is related by the famous relation. That's what Einstein's equation says (no hokey about relativistic mass please).

Now you know why it was so . :-D

I saw one guy in WIRED magazine say the amount of electrical power required to convert water to hydrogen to move a car 300 miles is measured in MEGAWATTS.

From http://hypertextbook.com/facts/1999/DavidFriedman. shtml Lightning. National Weather Service Office, Newport North Carolina. "The air near a lightning strike is heated to 50,000 degrees F, hotter than the surface of the sun!"