Heat Engines Shrunk By Seven Orders of Magnitude 168
KentuckyFC writes "The vast majority of motors that power our planes, trains, and automobiles are heat engines. They rely on the rapid expansion of gas as it heats up to generate movement. But attempts to shrink them by any significant amount have mostly ended in failure. Today, the smallest heat engines have a volume of some 10^7 cubic micrometers. Now group of Dutch engineers has built a heat engine that is seven orders of magnitude smaller than this. The engine consists of a piezoelectric bar that expands and contracts in the normal piezoelectric way. However it also heats up and cools at the same time causing a thermal expansion and contraction, which lags the piezoelectric displacement. By carefully choosing the frequency of the driving AC current, the Dutch team found a resonant effect in which the thermal expansion and contraction amplifies the mechanical motion, making it a true heat engine. Operating the thermodynamic cycle in reverse turns the device into a heat pump or refrigerator. The total volume of the device is just 0.5 cubic micrometres."
what about my car... (Score:1, Funny)
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Yeah a Beowulf cluster of them
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If engine of your car is much bigger than that, you should consider replacing your car.
0.215 millimeters width, length, and depth?
He obviously works for a car company.
On Chip cooling? (Score:2, Insightful)
Great! When can I get these built into my CPUs?
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It's not like a heat pump turns heat into nothing. One side of a heat pump gets cold, the other side gets hot. At half a micron across, it's hard to see how such a device could help evacuate heat from a CPU.
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It's not like a heat pump turns heat into nothing. One side of a heat pump gets cold, the other side gets hot. At half a micron across, it's hard to see how such a device could help evacuate heat from a CPU.
Just stick 100,000 of them end-to-end, naturally. Of course, I've no idea how efficient or effective they really are, but it seems like it *could* work.
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Stack arrays of them on top of each other between the CPU and the heat sync. Even if the temperature gradient is tiny over each layer it will add up, and even 1000 of them would be less than a millimeter thick.
Re:On Chip cooling? (Score:5, Interesting)
Already done: see peltier device. They are already made to the correct size and probably better efficiency.
http://www.peltier-info.com/ [peltier-info.com]
http://en.wikipedia.org/wiki/Thermoelectric_cooling [wikipedia.org]
Re:On Chip cooling? (Score:5, Insightful)
There *is* a need for heat reduction at very small scales, especially in mobile devices or even the implant devices of the future. Of course heat has to go somewhere, the only issue is that the destination of the heat be better able to deal with it than the source.
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And even the performance scale is just one of many axes in the space of the question, whether that concept is useful.
The size, for example, is another one.
Why do people always think in one-dimensional absolute extremes?
(Yes, I know that the “always“ is ironic. ^^)
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Peltier junctions are 'cool', but irrelevant to this. Unless my memory fails me, Peltier devices are not heat engines. They are solid-state thermoelectric devices. The devices here involve the Carnot Cycle of exchanging temperature and pressure in a four-sided cycle as do all heat engines. It's a bit weird at least for me to think about because they are also using the piezoelectric effect to drive or be driven by the cycle, so it's hard to think of these as simple heat engines. I will have to reread TF
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I love how a lack of imagination these days = impossible. I've decided to try responding to posts that claim "I can't imagine it, so since it's not possible..."
So, how about placing them together side-by-side so the cold side points down at the CPU and the hot side points up to the heat sink. This keeps the CPU cooler and the heat sink hotter (allowing it to dissipate more heat).
How about a tube made of the stuff--outside is hot, inside cool, through which you blow air? The tube itself can sit outside th
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If it's anything like pretty much every other really useful technological development that's occured in the last decade? You probably won't, but they'll always say it's N years away from commercial application.
Also they mention the ability to use it for refridgeration, but not whether it's still moving when they do that. Even on a microscopic scale having these things moving pretty much anywhere could cause problems.
Another way to save gas (Score:1)
Its a heat engine but it does not use gas, so maybe this could be the engine for a train of nano bots! Or we can use them to cool our CPUs. Interesting indeed, now we need to find an use for it
Re:Another way to save gas (Score:4, Funny)
If the heat were produced externally it would be a sort of Stirling engine. So I guess one this size would be Sterling sliver.
what is a cubic micrometer (Score:1, Funny)
Can the physics gurus please put cubic micrometers in perspective for us common mortals? Is that as big as a grain of rice or a head of a pin?
10^7 micrometers is.... a spehrical cow? a toaster?
Re:what is a cubic micrometer (Score:5, Informative)
A cubic micrometer is the volume occupied by a cube one micrometer on each side.
10^7 cubic micrometers would fill a cube about one-fifth of a millimeter on a side. Smaller than a pinhead.
Re:what is a cubic micrometer (Score:4, Informative)
about one-fifth of a millimeter on a side
That's about the thickness of a sheet of paper. (Round here, and probably in a lot of the world, the thickness and density of paper is specified, for instance "160 g/m^2, 200 micrometres".)
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(10^7) (cubic micrometers) = 0.01 cubic millimeters
Re:what is a cubic micrometer (Score:5, Funny)
Library of Congresses are a perfectly cromulent unit of volume. Just because the necessary measurements to derive the value are not easily google-able doesn't invalidate that fact.
In the past, when deriving the conversion from Library of Congresses to BTU's, we've used the assumption that we're talking about the books that make up the Library of Congress, not the building itself. This is because, back in the mists of time, Library of Congresses were originally used as a measure of information in the collection of the Library of Congress.
Anyhow, as a back-of-the-envelope estimate, 29 million books [wikipedia.org] at 1" x 10" x 8" gives us a value of ~50,000 cubic yards. That gives us a value of ((10^7) (cubic micrometers)) / (50 000 (cubic yards)) = 2.61590124 × 10-16 [google.com] Library of Congresses.
Screw this "metric system" with it's plethora of different units for different quantities. I strongly endorse that everybody normalize on Library of Congresses for units of any quantity. Just imagine how it would simplify your life!
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This car will drive 437 milliLibraries of Congress per nanoLibrary of Congress of gasoline! And with the low carbon emissions of just 4.3 picoLibraries of Congress of CO2 per microLibrary of Congress driven, it's great for the environment!
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So my car can travel approximately 1 Library of Congress on a full tank of gas.
Re:what is a cubic micrometer (Score:5, Informative)
Fun fact - Wolfram Alpha can serve as your 'self-checkout line' for things like this.
http://www.wolframalpha.com/input/?i=1+cubic+micrometer [wolframalpha.com]
Here's a bit of scale - a cubic micrometer is about the same size as a calibration bead for microscopy. A red blood cell is about 8 micrometers across. http://learn.genetics.utah.edu/content/begin/cells/scale/ [utah.edu] Or, there's this video showing the "powers of ten" (also its title...): http://www.youtube.com/watch?v=A2cmlhfdxuY [youtube.com]
Also, chemists work at these dimensions, too! (So do biologists. And others.) :*P Don't snub the other disciplines!!! Or I'll weep. And not gently, nor to a guitar.
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Can the physics gurus please put cubic micrometers in perspective for us common mortals? Is that as big as a grain of rice or a head of a pin?
10^7 micrometers is.... a spehrical cow? a toaster?
Yes, someone explain how many of them would fit into the library of congress.
Re:what is a cubic micrometer (Score:4, Funny)
Yes, someone explain how many of them would fit into the library of congress.
A metric assload.
Re:what is a cubic micrometer (Score:5, Funny)
That's no help - most Slashdotters are American. What's that in imperial assloads?
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That's "U.S. Customary [wikipedia.org]" assloads, Loyalist swine.
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I thought we had agreed to stop talking about the Bush administration... :-)
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Going from anecdotal evidence, I'd say the standard American assload is about 2.54 Continental European assloads.
It's 1% of a cubic mm (Score:2)
I agree that using cubic micrometers is nowhere near intuitive.
1 um (replace "u" with the Greek letter "mu" please) is 1e-6 metres.
So, 1 cubic um is 1e-18 cubic metres. So, the smallest conventional heat engines are 1e7 of these 1e-18 cubic metres, or 1e-11 cubic metres.
Not that intuitive either. So we'll use cubic mm.
1mm is 1e-3 metres, so 1 cubic mm is 1e-9 cubic metres.
Something that's 1e-11 cubic m (1e7 cubic um) is 1e-2 cubic mm. So, it's 1% of 1 cubic millimetre.
That's pretty small.
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A centimeter is about as far across as your pinky finger fingernail.
A centimeter is about half the distance across a penny (1.9cm), nickle(2.1cm), or dime (1.7cm).
So a square the size of a stack of pennies, 6 high (1.55mm each), would be 1 centimeter high, 4 centimeters square (2x2) and have 4 cubic centimeters.
A typical grain of rice appears to be about .2centimeters by 1 centimeter. So each grain of rice has roughly 1/25th of a cubic centimeter of material. So 25 grains of rice would roughly fill a cubi
Did someone say pump? (Score:1, Funny)
Can it be used for other things?
Re:Did someone say pump? (Score:4, Interesting)
If you've got a thing that small, it's time to give up on it...
Beer cans? (Score:2, Funny)
Re:Beer cans? (Score:5, Funny)
How many beer cans fit in a 0.5 micrometers refrigerator?
Depends. Are we talking micro- or macrobrews?
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And since we're talking about
You also forgot about the nano light-bulb, otherwise, you won't be able to see the beer in the fridge...
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I think we may have run into a small technical problem. Isn't the wavelength of visible light about 0.5 micrometres?
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You're thinking too small.
The correct question is, how many beer kegs fit in a 0.5 micrometer fridge?
Re:Beer cans? (Score:4, Funny)
0.00000000000000000852167911 beer kegs
If the fridge interior happens to be shaped optimally so that no space is wasted and the entire 0.5 micrometer fridge is filled with keg, then.. exactly 8.52167911 * 10^-18 beer kegs (if each keg is 15.5 gallons). [Incase someone wants to out-pedant me: Yeah, I understand you can't optimally shape a 0.5 micrometer fridge for a keg, when the size of 1 unit of keg > 0.5 micrometer fridge.]
Citation: http://www.google.com/search?hl=en&q=(0.5+micrometers%5E3)%2F(1+keg)&aq=f&aql=&aqi=&oq= [google.com]
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That depends. Are we talking about actual beers? [angryflower.com]
In a less huumorous vein, how many of these refrigerators does it take to cool a can of beer? It would be nice to have cold beer with a built in refrigerator in every can. Provided it could be done cheaply enough.
Heat engine != internal combustion engine (Score:3, Insightful)
Re:Heat engine != internal combustion engine (Score:5, Informative)
Somehow "heat engine" directly translates into "internal combustion engine" for me.
That's too bad, I hope this article will be enough to let you correct your thought
why emphasize that it is a heat engine?
Because they figure it's mostly usefull as a heat pump, not as a mechanical actuator.
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I RTFA, and I still have serious doubts about the terminology used here and there.
What TFA describes is actually an electric motor. They apply AC & DC, and got mechanical work :
The new heat engine is essentially a bar of piezoelectric material whihc expands and contracts when an alternating current is applied
Well guess what? That's no heat engine, that's an electric motor. It also happens to release some heat, but so does every motor.
They didn't describe the reverse process (heat engine or refrigerator).
Maybe this product really *is* a heat engine, but that's not what's described in TFA.
Re:Heat engine != internal combustion engine (Score:4, Informative)
The internal combustion engine is only one class of heat engines. The Sterling Engine and the External Combustion Engine (used in old steam locomotives) are also heat engines. Heat engines use heat to create power either by taking advantage of temperature differences or the expansion of heated air.
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Probably just trying to get some free publicity when California bans it.
Re:Heat engine != internal combustion engine (Score:5, Informative)
Somehow "heat engine" directly translates into "internal combustion engine" for me.
A steam engine is an external combustion engine, yet is is still a heat engine. The thing with this teensy engine is that it reuses waste heat rather than throwing it away, making it far more efficient than your ordinary electric motor.
As a side note, the difference between a motor and an engine is that a motor rotates, an engine reciprocates. You can indeed have an electric engine (theyre usually called "solenoids") and a gasoline motor (Mazda had "rotary engines" back in the '70s; they were actually gasoline motors.)
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Mazda had "rotary engines" back in the '70s; they were actually gasoline motors.
Had? Wouldn't "have had ... since [wikipedia.org]" be more accurate? (oh, and it's since 1963 [wikipedia.org], so the '60s...)
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As a side note, the difference between a motor and an engine is that a motor rotates, an engine reciprocates.
Huh. I didn't know that.
So I guess that means that Wankel was being a bit of a Wanker when he named his Wankel Rotary Engine, huh?
Re:Heat engine != internal combustion engine (Score:5, Informative)
As a side note, the difference between a motor and an engine is that a motor rotates, an engine reciprocates.
Huh. I didn't know that.
Not surprising that you didn't know that, since it isn't true.
An engine is a machine that does work using a source of energy like the coiled rope of a catapult or the tank of gas for your internal combustion engine.
A motor is an engine that moves something, like, say, a motorcycle.
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That's what I thought. :/
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Sir, poorly played. You should never pass up the opportunity to use the word "Wankel [wikipedia.org]" in a sentence.
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As in, "I built a working model of a Wankel Engine in high school?"
Wow. That is win.
How 'bout this, "I had a Wankel when I was a teenage boy?"
Hrm... Not so much.
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"making it far more efficient than your ordinary electric motor"
Um, electric motors are 90%+ efficient, so how much is "far more"?
The actual details in the linked blog are a tad hazy and possibly even incorrect.
The article says that because of the mechanical change the resistance of the crystal is changed, therefore the heat generated by the DC current changes. Then it makes a rather large hop, or more like a giant leap, and says that thus one side heats up and the other cools down. Unfortunately, this is n
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The main difference between a solenoid and a relay is that in a relay, the electromagnet moves a flap-like thing that connects and disconnects circuts, while a solenoid is an electrically driven piston. They are similar, but solenoids usually move a non-electrical component (picture the remote trunk opener in your car) while a relay is a remotely driven switch, usually used to use low voltage/current to switch a high voltage/current circuit. That's not their only use; a digital computer was built by at leas
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The description in the summary is really only *half* a heat engine. It turns electricity into work, yah, but it also turns work (in the form of electricity) into temperature difference.
What it does not do is turn a temperature difference into work, which is the other half of the equation. A heat engine must do at least one of the two, and it has been proved that the maximum efficiency occurs for reversible processes, so many heat engines are capable of both.
Isn't this a... (Score:1)
Peltier diode?
More Entropy, that is exactly what need... (Score:2)
I guess the Logopolians will have to spend even more time doing base block calculations to prevent the heat death of the universe.....
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Wasn't that Block Transfer Computations?
0.5 cubic micrometres?! (Score:2, Insightful)
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I am 8.45^10 nanometers tall! (Score:2)
Not exactly hidden information either.
Tough call (Score:2, Interesting)
Read the attached paper... (Score:5, Interesting)
I read the attached paper on arxiv, and from what I could tell, they passed a DC current through the thing, which caused the small engine beam to expand, causing it to heat up and move the mass. The piezoelectric effect causes the resistance in the small engine beam to change, which causes the beam to cool down and move the mass back with help from the larger spring beam. Rinse, repeat. Effectively a thermoelectric buzzer. The buzzing of this particular device was measured to be about 1.255 MHz at a DC current of 1.045 mA.
Unlike what the Technology Review article says, the paper shows no application of an AC current to get the thing vibrating. In fact, the measured voltage is alternating because the resistance is alternating. The current remains the same. There is no complicated application of a DC current and an AC current. There's just an applied DC current.
Am I understanding the paper correctly?
There's more. Thermoacoustic applications? (Score:2)
As far as you went.
But the alternating heating/cooling doesn't have to come from current through the m
Re:Usefulness? (Score:5, Funny)
It is so small that it produces a very minimal amount of horsepower, which is not useful for any actual way.
Unless of course you have several billion of them on a gram sized object. If you can't see the value in jet powered ants you should turn in your nerd card.
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Re:Usefulness? (Score:5, Interesting)
Assuming we had micro engines, we can take full advantege of many things that are better smaller than bigger.
For example, a small device that turns heat into power could power an IMPLANTABLE MEDICAL DEVICE using the bodies own heating/cooling systems? No more changing the battery for the pacemaker every
Then there are small flying devices. I am sure the military would love a flying camera the size of a real fly that uses the solar heat of the sun to power it.
Then there are phones and musical devices. Want one that uses half of its' own waste heat to recharge itself, perhaps doubling battery life?
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There's a reason we don't already use the waste heat for recharging electronics... because it's damn expensive. There are far better components for turning a heat gradient into electricity than this type of motor.
Looking at your other examples... the promise of this device is not in turning heat into electrical power. It's about turning heat into physical power. Thi
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Unfortunately, both the article and the summary have left out that detail...
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For example, a small device that turns heat into power could power an IMPLANTABLE MEDICAL DEVICE using the bodies own heating/cooling systems?
How would that work?
To power a heat engine, you need a temperature difference.
To power a heat engine efficiently, you need a temperature difference significant in comparison to the absolute temperatures.
As the temperature difference approaches 0, the efficiency approaches 0.
The maximum theoretical efficiency between body temperature and body temperatue + 3C is about 1%
How much of a temperature difference do you think you can find within the human body across a machine of a few micormeters (or even mill
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How much of a temperature difference do you think you can find within the human body across a machine of a few micormeters (or even millimeters) in length?
That's what the 12" heat sink sticking out of your chest is for. That, and impressing the ladies.
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So as you shrink things, pretty soon, you can't start a fire. The fire loses heat over its surface area faster than itrs volume can generate it.
Which is why you don't see flames smaller than a certain, much larger than micrometer, size.
So if I'm understanding this argument correctly, the limitation can also be understood in terms of the time window available in which to extract the energy decreases, as the engine scales down. At a material level, the heat dissipation has a limit as well -- for conduction, it can't be any faster than the speed of sound (within the material comprising the engine).
While we don't have any information on the frequency at which the piezo engine operates, it could be very high, allowing for nearly instant energ
Re:Reeedeeeculous (Score:5, Insightful)
And I despair of the lack of English education, specifically reading comprehension.
This isn't internal combustion, which is what your argument is based on. It uses the fact that solids expand and contract when heated and cooled, including some piezo materials.
Please read the summary *again*.
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To be fair, its a poorly written summary that can easily cause anyone who doesn't have a background in this area of engineering to assume it's only talking about internal combustion engines because of the first two to three sentence:
"The vast majority of motors that power our planes, trains, and automobiles are heat engines. They rely on the rapid expansion of gas as it heats up to generate movement. But attempts to shrink them by any significant amount have mostly ended in failure."
This could be interprete
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it makes no difference if it's an IC engine or ZC.
The issue is the same. To have a heat engine you need separate regions, one hot and one cold. As the regions get smaller, you lose the ability to keep the hot away from the cold. By the time you're down to 1 centimeter, a large fraction of the heat is lost thru conduction. And it just gets worse from there on down.
And using differential expansion of a solid is a horribly inefficient scheme-- you may have noticed a certain lack of cars powered by the exp
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>Please read the summary *again*.
yes, you read it again too, especially this part:
Below the 1-mm limit, efficiency suffers to such a degree that solid-state thermoelectric devices would become a better choice for a particular application. "
So this device is rated NFG at smaller sizes, by the inventors themselves. .. and I havent even touched on how friction and surface tension also go down as the square, making moving parts below a certain size just plain useless.
Re:Reeedeeeculous (Score:5, Insightful)
Re:Reeedeeeculous (Score:4, Insightful)
What has happened to Slashdot? Who do you have to be a Guru in every subject to read Slashdot?
Looks like gone are the days when all you needed to good discussions on Slashdot was genuine curiosity and decent , not necessarily perfect, grasp of English language. And no, being a know-all, done-all master of the universe was not required either.
While I can perfectly understand saying "You are making a mistake" or "That's not what the article says", I have never really understood calling someone pathetic for not knowing something.
The range of topics covered here is very wide and I don't know abc of several things discussed here. Does that make me stupid and pathetic?
Re:Reeedeeeculous (Score:5, Insightful)
The range of topics covered here is very wide and I don't know abc of several things discussed here. Does that make me stupid and pathetic?
The key point is that you recognize that you don't know everything about the topic at hand. The post that sunking2 was responding to was essentially a spew of vitriol against the researchers, claiming that it's impossible to make such a small engine with any sort of efficiency, and that they're stupid and ignorant for even trying. According to that post's replies, the writer is completely wrong and doesn't know some basic facts about the subject they're yelling about.
So, no, you're not at all stupid and pathetic for not knowing everything about everything, and I'm in the same boat with you (I've learned a fair amount from this story's discussion), but neither of us is telling everyone (including the Dutch engineers in question) that they're stupid and don't know what they're talking about.
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... but neither of us is telling everyone (including the Dutch engineers in question) that they're stupid and don't know what they're talking about.
Don't worry. That's just the usual style of Dutch engineering discourse.
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No, your post was polite and respectful, so you're not stupid and pathetic (even though I don't agree with you). The original ("Reedeeculous") post was both incorrect and rude, and the response was appropriate (correct and rude). If the original post had been incorrect and polite, I'm sure the tone of the responses would be very different. If you act like a know-it-a
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Looks like gone are the days when all you needed to good discussions on Slashdot was genuine curiosity and decent , not necessarily perfect, grasp of English language. And no, being a know-all, done-all master of the universe was not required either.
True but you were also expected to recognize that you were not a know-all done-all master... There was never a time on /. where someone who said "I'm right and all these fools have no idea what they're doing" wouldn't result in the poster being smacked down if
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Stop copying me!
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Stop copying me then traveling back in time to post first! Total waste of a time machine. ;)
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"The range of topics covered here is very wide and I don't know abc of several things discussed here"
makes you 'wise' in the Socratic sense, negating the description "stupid"
unfortunately, the location of this discussion reinforces the second descriptor
Re:Reeedeeeculous (Score:5, Insightful)
It's the basic SCALING LAW that Galilleo figured out like 600 years ago.
As you make things smaller, their volume, which is their abilitry to burn fuel, goes down as the CUBE of its linear dimension.
But its surface area, which is how it loses heat, only goes down as the square.
That'd be Newton's law of cooling, no more than 300 years old.
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How did this get +3 informative?
How about -1 "did not read the summary and assumed it was an IC engine".
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What does Immigration and Customs Enforcement have to do with piezoelectric heat engines?
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