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Suppose that the perception of the heat of a solid or liquid body is closely related to the rate at which heat passes from that body into a human body.
Suppose likewise that the perception of coldness of a solid or liquid is closely related to the rate at which heat passes in the other direction.
Build
a standardized approximation to a human fingertip as it behaves at a standardized initial ambient temperature (say, room temperature), incorporating a sensor to measure the rate of transfer of heat energy into or out of it.
This device will then give you an objective approximation to how hot or cold a solid or liquid body is likely to feel subjectively. Unlike, say, a thermometer reading, it will take into account such things as the greater conductivity of metal over wood (which tend to make true temperature less helpful in this regard).
You could see this as an extension of the idea of "wind-chill factor", but with more clarity about what it's really measuring.
Psychophysics of Temperature Perception
http://ieeexplore.i...1&authDecision=-203
Not sure it's that straightforward [csea, Mar 21 2010]
Thermal Flux sensor
http://wuntronic.eu...8&subid=153&pid=307
Something like this should work [csea, Mar 21 2010]
Force
http://museums.leic...do?objectKey=270129
Suddenly, this makes sense. [pertinax, Mar 23 2010]
Lukewarm, etymology of.
http://en.wiktionary.org/wiki/lukewarm
[DrBob, Mar 25 2010]
Star Wars RetCon
http://en.wikipedia...ist_of_retcons#Film
Was Anakin betrayed & killed by Darth Vader, or _is_ he Darth Vader? Is Leia Organa an upper-class love interest for Luke, or his sister? Only Retroactive Continuity can tell. [land, Mar 26 2010]
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This is a very good idea.
[+] |
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[+] plain old "chill-factor" is a nice nounverb for coldth offset... "sweat-factor" for positive ? |
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I like the concept, but think it would be applicable over a fairly narrow range of temperatures. Fingertip touches to certain very cold surfaces may be perceived as "hot." And I suspect there may be a fairly fuzzy relationship between temperature sensing and pain. |
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And Joules/sec are just Watts. What's wanted is a thermal flux measurement, i.e. W/m^2. Let me see if I can find a link. OK, here: [link2]. |
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Would this be psychophysics or psychrotrophics? |
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Trying to measure sensations or perceptions has much in common with herding cats, but still this is an interesting idea and surely must have some applications somewhere. |
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I like the concept, though I have an overwhelming urge to
raise technical quibbles. |
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//standardized approximation to a human fingertip// It
would have to model the vasoconstrictive response
to cold. I'm not sure how consistent that is across
individuals. I think in people with Reynaud's syndrome the
nonlinearities might give your engineers the heebie-
jeebies. |
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...and wouldn't you need separate scales for fingers, toes,
nose & ears? If you were male, and planning on running
naked from sauna to icy pond, would you need a fifth
scale? |
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On the other hand, I think the subjectivity of temperature
perception might *not* be a problem because this idea is
about pain-perception, not temperature-perception. For
heat, the temperature threshold isn't actually all that
variable (it's 45 degrees). For cold, I'm not sure. |
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Subjectivity would be an issue, but so is it for conventional
wind-chill and even static air-temperature measurements.
The weatherman says 5 degrees, but listeners will decide
whether they think that's cool, cold or intolerable. |
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Likewise, a measurement that accounts for the thermal
conductivity and thermal mass of objects will be absolute,
and people will interpret it subjectively for themselves. |
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What about that thing where you run one finger under the hot tap, then another finger under the cold one, continuing this for 30 seconds or so in order for your fingers to habituate, and then plunge them both in a container full of luke-warm (who *is* Luke anyway?) water. |
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// who *is* Luke anyway? // |
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Anakin Skywalker's son. He has a sister, Leia. |
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Please, try to keep up ... |
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I knew that much (I felt his presents) my question is more to do with him being identified as an indicator of temperature? |
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It's the Force that makes him warm - it's a
well-known side-effect of exposure to
higher-than-recommended levels of Force. |
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//who *is* Luke anyway?) //
Christopher Biggins' character in "Porridge". |
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Luke-warm Porridge ? Hmmm .. |
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That poor baby bear, everybody is after his porridge... |
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Even Luke now, alas, I thought he was supposed to be on the side of good. |
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coincidentally [+] for the idea |
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// I thought he was supposded to be on the side of good. // |
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We would apologise for disillusioning you, but actually we rather enjoy that sort of thing .. |
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'I believe you find life such a problem because you think there are the good people and the bad people. You're wrong, of course. There are, always and only, the bad people, but some of them are on opposite sides.' (Terry Pratchett, "Guards ! Guards !") |
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//room temperature//
Did you have any particular room in mind, pertinax? |
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How about a genital scale, measuring the retraction when exposed? Or the nipple scale of course. |
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[marklar] //measuring the retraction when exposed// I recall
a paper on that very subject in the Journal of Irreproducible
Results. |
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// Anakin Skywalker's son. He has a sister, Leia. // |
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Only as a result of retroactive continuity, my good man. See
[link5] |
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//I have an overwhelming urge to raise technical quibbles.// Excellent, [mouseposture], that's what shows you're one of us. :-) |
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Yes, we would hate to think that you might be one of Them ... |
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Baked: Fahrenheit is already based on Rømer's scale,
which was based on the temperature of a healthy
man, at least according to an MIT video lecture I saw.
I haven't been able to back that up otherwise).
Wikipedia says Rømer based it on the freezing and
boiling of water. |
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// I like the concept, though I have an overwhelming urge
to raise technical quibbles. // |
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[zen_tom], back in 2010 said "I knew that much (I felt his presents)" |
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When did a Christmas tree get into this conversation? |
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My understanding was that Farenheit was based on the freezing and boiling points of seawater. |
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Unfortunately, since the salinity of seawater is variable, this is a lousy thing to base a temperture scale on. |
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Nope. Originally, 96 degrees Fahrenheit was body
temperature, and 0 degrees Fahrenheit was “colder
than it ever gets in Denmark”. Later, 0 degrees was
redefined to be the stable temperature of a mixture
of ice, water, and ammonium chloride, and some
additional tweaks were made to get pure water to
freeze at 32 and boil at 212, which caused the body
temperature point to shift upwards a bit. |
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Meanwhile, somebody with all ten fingers and a bucket
that didn't leak was off somewhere inventing the Celsius
scale, which, like an Apple Computer, is simple, functional,
and aesthetically pleasing, but is only just now coming into
its own having suffered from earlier marketing failures. |
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I double checked, the only really fixed point, zero,
was based on a brine (not seawater, admittedly). He
started with water at 30 and body temp at 90, then
revised the scale so he could use regular divisions to
draw it out. |
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//Celsius scale… is simple, functional, and aesthetically pleasing// |
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The Celsius scale sucks. I can understand the logic behind the rest
of the metric system, but there's no justification for using Celsius
over Fahrenheit for anything. |
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The freezing and boiling points of water are completely arbitrary
standards, and they're not relevant to anything you do in your daily
life. Have you ever stepped outside and said, “I wonder how much
hotter it would have to be for water to boil?” No, of course not.
Have you ever said “I need to calculate precisely how much colder
it would have to be for ice to form if I were at sea level right now?”
I sort of doubt it. |
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With Celsius, you have to use negative numbers and decimals with
far greater frequency, because the scale isn't calibrated to be
useful to human beings. A roughly 0-100 scale for most things you'll
encounter in your daily life is quite convenient. -18 to 38 is just
annoying. And it's not like you can add, subtract, or multiply
temperatures anyway, so what's the point? |
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The Kelvin scale at least makes some sense, and I can see a use for
it in scientific applications, but even there it's not really any better
than the Rankine scale, which is essentially the same thing but in
Fahrenheit gradations. But Celsius simply has no reason to exist. |
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First of all, a great deal of modern-day life revolves around
the boiling of water, the freezing of water, or any number
of operations related to or extrapolated from one or both. |
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Second, as arbitrariness goes, 32 and 212 are a whole lot
more nonsensically arbitrational than 0 and 100. |
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Third, if you don't like using decimals, simplify things by
using 'anna half' instead. |
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Fourth... well, okay, I'm out, but the only thing Farenheit
really has going for it is that it fits right in with the rest of
the idiomatic metrics we use here in the States. |
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They're both crap: what idiot decided "98.6 is the new 100" and "the magic number where you have to start scraping ice off the windshield and all your plants die is 32" ? |
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Celsius is even worse (barring the 0 = ice bit), all the reasonable temperatures for human beings are between 10 and 30, that's only a 20 degree range. |
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Almost as bad as the kilometers per hectare (or whatever) mileage ratings we have here. All (regular'ish passenger) cars run between 6-10... that's even simpler (and not in a good way) than counting on fingers. |
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//First of all, a great deal of modern-day life revolves
around the boiling of water, the freezing of water, or any
number of operations related to or extrapolated from one
or both.// |
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Oh, right, Maine. Well, in the rest of the country, we have
these amazing things installed in our walls that, believe it
or not, dispense actual drinkable water on demand. You
don't even have to chop any firewood to get a drink of
water by melting snow in the middle of the night! And in
the summer, water is actually safe to drink as-is—no boiling
necessary. In actual fact, very little of what I do
throughout the day involves either freezing or boiling
water, and when it does I don't especially care at what
temperature it happens. “Really hot” or “really cold” work
just fine. |
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//Second, as arbitrariness goes, 32 and 212 are a whole lot
more nonsensically arbitrational than 0 and 100.// |
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But you almost never care about the freezing and boiling
points of water within the same application. So, why would
you design a scale based on those two numbers? Step
outside and the temperature is very likely to be between 0
and 100 Fahrenheit wherever you are in the world.
Anywhere outside this range would be considered extreme.
/That's/ useful. Don't you step outside quite a bit more
often than you need to calculate the temperature
differential between freezing and boiling water? |
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//Third, if you don't like using decimals, simplify things by
using 'anna half' instead.// |
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Or, just double the whole scale so you don't have to even
deal with that. Then add about 30 degrees or so to get rid
of those annoying negative numbers as well. Hmmm. |
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OK, so what 2 events would anyone here use instead
of ice/boiling points of water, and how would *any*
such choice be any more/less arbitrary than any
other one? |
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//The freezing and boiling points of water are completely arbitrary standards, and they're not relevant to anything you do in your daily life. Have you ever stepped outside and said, “I wonder how much hotter it would have to be for water to boil?” No, of course not. Have you ever said “I need to calculate precisely how much colder it would have to be for ice to form if I were at sea level right now?” I sort of doubt it.// |
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You really didn't think about that for long, did you? People *routinely* need to deal with temperatures close to both the boiling and freezing point of water, in their daily life[1]. |
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They may be arbitrary and approximate[2], but if you are looking for robust points which virtually everyone can easily understand, they're it. |
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//With Celsius, you have to use negative numbers and decimals with far greater frequency, because the scale isn't calibrated to be useful to human beings. A roughly 0-100 scale for most things you'll encounter in your daily life is quite convenient. -18 to 38 is just annoying. And it's not like you can add, subtract, or multiply temperatures anyway, so what's the point?// |
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Most people routinely deal with temperatures well above their body-temperature. Let's take boiling point as the max most people will trypically need to measure.
Most freezers hold at -20 degrees C, lets take that as the minimum.
The freezing point of water is also a useful transition, which would be nice to have as an easy number in the scale.
So which is better: -4,32,212 or -20,0,100? |
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[1] A few examples for both
Boiling water : cooking, preparing hot drinks, sterilising
Freezing point of water : storing food (perishable - a few degrees above; long-term - a few degrees below), driving in potentially dangerous conditions, caring for plants |
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[2] Celsius is actually now defined using absolute zero and the triple point of water, but the difference is not important "in everyday life". |
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//what 2 events would anyone here use//
Lower limit = temperature at which you notice that your feet are sticking out of the bottom of the duvet.
Upper limit = point at which you don't need the duvet in the first place.
Shall we talk about how fine the scaling should be now? |
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If you need a fine scale, just start using decidegrees C. It is the SI standard, which means the prefixes are just as applicable. |
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Thanks all. I also meant that daily life involves the boiling
and freezing points of water in the more abstract sense;
automotive technology, for instance, uses both figures in
direct application and as reference points. |
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//You really didn't think about that for long, did you? People *routinely*
need to deal with temperatures close to both the boiling and freezing
point of water, in their daily life// |
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I already addressed this point in a later anno. Don't confuse “dealing with
temperatures” and “measuring temperatures”. When you're cooking, do
you measure the temperature of your pot of water as it gets to the
boiling point? I don't, and neither does anybody else. You just put it on
the stove, and when it boils, you add the pasta. |
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Same thing with your refrigerator or freezer. I've never measured the
exact temperature of my appliances. I know that the refrigerator will
keep things cold, and the freezer will freeze them. I don't care where
exactly they are relative to the triple point of water. It's just not that
useful a metric. |
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Pretty much the only things most people care about the actual
temperature for are:
The weather — for which 0-100 is a very convenient
scale
Body temperature — over 100 is a fever, also convenient
Adjusting the thermostat — where the finer gradations come in handy,
allowing you to avoid decimals or fractions
Setting your oven — since all temperatures are well over the boiling point
of water, and you're not boiling water anyway, no real advantage to
either system there
So for most practical purposes, Fahrenheit is a
demonstrably better scale to use, and in no case is it worse than Celsius. |
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The argument that the metric system makes it easier to do math when
converting between units falls flat when it comes to temperature,
because you can't do math on temperature in any meaningful way. I
challenge anyone to find a demonstrable way in which measuring in
Celsius makes things simpler than Fahrenheit or Kelvin. |
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As someone pointed out somewhere, older people in
England use Celsius for temperatures below freezing,
and Fahrenheit for temperatures above freezing. A
hot day might be in the 80's, but a cold night might
go down to -5. Go figure. |
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That's just because they want to make things sound
as extreme as possible (the “Four Yorkshiremen”
sketch springs to mind). |
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I'm plumping for the Delisle scale, where smaller
numbers represent higher temperatures. |
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Kelvin is the one that makes it easy, as it's the one used when you are multiplying or dividing temepratures. For addition and subtraction, it, of course, doesn't matter if you use Celsius or Kelvin. |
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Regardless, the critical thing is that the constants in your formula match up with your units. Since metric formulae typically use Celsius/Kelvin and imperial typically use Farenheit/Rankine, and since metric is easier to use for everything else, it's easier to do math with Kelvin. However, since I'm most often working around room temperature, I'm working with simpler numbers if I use celsius and simply add 273.15 before I do any multiplication. |
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I use Fahrenheit, Celsius, and Kelvin on a semi-regular
basis, although I use them all in different applications and
will freely admit that I never perform any conversions. My
argument against Fahrenheit is my argument against all
idiomatic metrics: they don't make any bloody sense. Now,
I grew up using inches, feet, yards, miles, ounces, pounds,
tons, cups, pint, quarts, and gallons just like every other
pie-eating flag-waving gun-toting American child, but the
only reason I'm able to keep any of it straight is because
I've had it hammered into my skull since Kindergarten. On
the other hand, anybody capable of counting to ten can
measure _anything_, including temperature, using the
Metric system. |
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