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>> How come human
>> brains don't ignite and burn during normal operation? I don't see any
>> really large heat sinks on a human...
>
> It is fluid cooled and what about those heatsinks on the side of your head?
Water cooled? Elite!
But I mean, *damn*, you'd have to have a high-volume fluid pumping
system, and a very large surface area to dissapate the heat over.
...oh, wait...
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> As an aside... How much heat does the human brain generate?
You can do a quick estimation by seeing how much heat is radiated, the skin
temperature is approximately 32 degrees, room temperature is 20 degrees, and
the surface area of your head is, umm about 0.08m^2. Using the
Stefan-Boltzmann law I make that about 6W of radiated heat. Given that the
human body generates about 100W, I think the 6W figure is too low, as some
of the heat from the brain will be taken into the body by the blood stream
(liquid cooling!). I guess around 20W would be a more sensible figure.
> (By every estimate I've seen, it has vastly superior theoretical
> computational power compared to any supercomputer yet built by man.)
If my computer were as slow as me doing sums it would probably run on solar
power in the dark! And if I tried to do 3 billion sums in one second my
head would surely explode.
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scott wrote:
>> As an aside... How much heat does the human brain generate?
>
> Given
> that the human body generates about 100W, I think the 6W figure is too
> low, as some of the heat from the brain will be taken into the body by
> the blood stream (liquid cooling!). I guess around 20W would be a more
> sensible figure.
http://vadim.oversigma.com/MAS862/Project.html
Suggests that the entire body consumes about 100W, and the brain itself
uses 20 - 40 W. (So... a pretty significant fraction, considering that
the human body is *not* a data processing device, primarily.) That's how
much energy it *uses*, I wonder how much of that ends up as heat?
>> (By every estimate I've seen, it has vastly superior theoretical
>> computational power compared to any supercomputer yet built by man.)
>
> If my computer were as slow as me doing sums it would probably run on
> solar power in the dark! And if I tried to do 3 billion sums in one
> second my head would surely explode.
Well, you say that, but how many "sums" does it take to compare a
snippet of sound to many millions of other recorded examples like it and
determine that, yes, this is The Beetles singing "All you need is love"?
The human brain doesn't work the same way a computer does. This isn't
exactly news. Indeed, this is why computers are useful in the first
place! But based on the number of switching elements in a computer vs
those in the brain, AFAIK the brain comes out rather favourably.
(The same website above gives the number of transisters in a Pentium IV
as K * 10^7, while the number of neurons in a brain is K * 10^11. Kind
of a big difference...)
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Invisible wrote:
> http://vadim.oversigma.com/MAS862/Project.html
"The power consumption of the Pentium 4 may exceed that of the human
brain. That explains why Pentium cooling systems are getting close in
size to the human head."
I LOLd! :-D
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> Suggests that the entire body consumes about 100W, and the brain itself
> uses 20 - 40 W. (So... a pretty significant fraction, considering that the
> human body is *not* a data processing device, primarily.) That's how much
> energy it *uses*, I wonder how much of that ends up as heat?
Well there aren't too many options for "used energy" to be converted to.
Maybe some is used to increase the kinetic energy of some blood, but I would
say that almost all is converted to heat.
> The human brain doesn't work the same way a computer does. This isn't
> exactly news. Indeed, this is why computers are useful in the first place!
> But based on the number of switching elements in a computer vs those in
> the brain, AFAIK the brain comes out rather favourably.
I guess the brain also makes even Windows ME look good for uptime records
:-)
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scott wrote:
>> Suggests that the entire body consumes about 100W, and the brain
>> itself uses 20 - 40 W. (So... a pretty significant fraction,
>> considering that the human body is *not* a data processing device,
>> primarily.) That's how much energy it *uses*, I wonder how much of
>> that ends up as heat?
>
> Well there aren't too many options for "used energy" to be converted to.
> Maybe some is used to increase the kinetic energy of some blood, but I
> would say that almost all is converted to heat.
Well, I guess the brain does use *some* of that energy for chemical
transformations. (It turns raw ingredients into hormones and releases
them, for example.) But yeah, *most* of it is porbably heat...
FWIW, how much heat does an Intel Core 2 Quad generate?
> I guess the brain also makes even Windows ME look good for uptime
> records :-)
HAHAHAH! PWN3D! :-D
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> FWIW, how much heat does an Intel Core 2 Quad generate?
About 120W under full load.
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scott wrote:
>> FWIW, how much heat does an Intel Core 2 Quad generate?
>
> About 120W under full load.
...so, more than an entire human being?
Perhaps *this* is why the human brain is in little danger of burning to
a crisp? ;-)
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On Fri, 09 Jan 2009 10:26:48 +0000, Invisible <voi### [at] devnull> wrote:
>>> How come human
>>> brains don't ignite and burn during normal operation? I don't see any
>>> really large heat sinks on a human...
>>
>> It is fluid cooled and what about those heatsinks on the side of your head?
>
>Water cooled? Elite!
>
>But I mean, *damn*, you'd have to have a high-volume fluid pumping
>system, and a very large surface area to dissapate the heat over.
>
>
>
>...oh, wait...
Yes, the cardiovascular system is an effective heat exchanger working with the
lungs and skin. :)
--
Regards
Stephen
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>> About 120W under full load.
>
> ...so, more than an entire human being?
>
> Perhaps *this* is why the human brain is in little danger of burning to a
> crisp? ;-)
Maybe not burning to a crisp, but if you raise the temperature of your
innards by just a few degrees things begin to screw up very rapidly. You
have quite a sophisticated temperature control system to keep you at around
37 degrees inside...
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