Re: [math-fun] Miscounting in the Cheddar Gorge ...
This was converted from 37.0 Celsius. Leo On Nov 12, 2017 22:23, "Andy Latto" <andy.latto@pobox.com> wrote: My favorite precision fail is the one for human body temperature. It's generally quoted in the US as 98.6 degrees Fahrenheit, but this was obtained by converting the value of 37 degreed Celsius, so a number with a precision of a Celsius degree was converted to one that people think has a precision of a tenth of a Fahrenheit degree. Andy On Sun, Nov 12, 2017 at 4:15 PM, Keith F. Lynch <kfl@keithlynch.net> wrote:
Guy Haworth <g.haworth@reading.ac.uk> wrote:
The Cheddar Gorge is 10,000,001 years old this year.
I know this because last year ...
That's a precision fail, not a counting fail. It's perfectly valid to add one year to the age of something each year, no matter how old it is. Except that the age of very old things is seldom known to the nearest year. And gorges, unlike, say, individual dinosaurs, don't have precise birthdays anyway. (That joke is more commonly told about dinosaurs, with a museum guard answering that a particular specimen is is 100,000,003 years old, or whatever.)
Also, for very high precision or for extremely long distances or times, the age depends on the trajectory of the clock.
For instance how old is Mount Everest? I haven't been able to find that number anywhere. Wikipedia says it's 8848 meters tall and that the Himalayas are growing by 5 millimeters per year. That would imply an age of 1769600 years. If, at the instant the mountain started its climb from sea level someone had placed a perfect clock where it would ride up the peak and another perfect clock where it would remain at sea level, today the two clocks would disagree by 24 seconds as to the age of the mountain, due to general relativity.
You'd get far more variance on how long ago the Big Bang was, since there are so many choices of "reasonable" trajectories for a clock that formed that very instant and conveniently lands in from of you just when you want to know the age of the universe.
Precision fails are very common. For instance:
Naturally, this means that it's ridiculously hot on the planet's surface, with temperatures reaching 2000 degrees Celsius (3632 Fahrenheit), ...
https://www.outerplaces.com/science/item/16744- astronomers-planet-titanium-atmosphere
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On Sat, Nov 18, 2017 at 11:11 AM, Leo Broukhis <leobro@gmail.com> wrote:
This was converted from 37.0 Celsius.
Do you have a source for the value being given to three significant figures in Celsius? I looked online, and found "Normal body temperature is considered to be 37°C (98.6°F); however, a wide variation is seen. Among normal individuals, mean daily temperature can differ by 0.5°C (0.9°F), and daily variations can be as much as 0.25 to 0.5°C" on the NIH site at https://www.ncbi.nlm.nih.gov/books/NBK331/, quoted from "Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.". If it varies among individuals by .5 decrees C, and daily variations can be as much as .5 degrees C, 37 seems a better description than 37.0
Leo
On Nov 12, 2017 22:23, "Andy Latto" <andy.latto@pobox.com> wrote:
My favorite precision fail is the one for human body temperature. It's generally quoted in the US as 98.6 degrees Fahrenheit, but this was obtained by converting the value of 37 degreed Celsius, so a number with a precision of a Celsius degree was converted to one that people think has a precision of a tenth of a Fahrenheit degree.
Andy
On Sun, Nov 12, 2017 at 4:15 PM, Keith F. Lynch <kfl@keithlynch.net> wrote:
Guy Haworth <g.haworth@reading.ac.uk> wrote:
The Cheddar Gorge is 10,000,001 years old this year.
I know this because last year ...
That's a precision fail, not a counting fail. It's perfectly valid to add one year to the age of something each year, no matter how old it is. Except that the age of very old things is seldom known to the nearest year. And gorges, unlike, say, individual dinosaurs, don't have precise birthdays anyway. (That joke is more commonly told about dinosaurs, with a museum guard answering that a particular specimen is is 100,000,003 years old, or whatever.)
Also, for very high precision or for extremely long distances or times, the age depends on the trajectory of the clock.
For instance how old is Mount Everest? I haven't been able to find that number anywhere. Wikipedia says it's 8848 meters tall and that the Himalayas are growing by 5 millimeters per year. That would imply an age of 1769600 years. If, at the instant the mountain started its climb from sea level someone had placed a perfect clock where it would ride up the peak and another perfect clock where it would remain at sea level, today the two clocks would disagree by 24 seconds as to the age of the mountain, due to general relativity.
You'd get far more variance on how long ago the Big Bang was, since there are so many choices of "reasonable" trajectories for a clock that formed that very instant and conveniently lands in from of you just when you want to know the age of the universe.
Precision fails are very common. For instance:
Naturally, this means that it's ridiculously hot on the planet's surface, with temperatures reaching 2000 degrees Celsius (3632 Fahrenheit), ...
https://www.outerplaces.com/science/item/16744- astronomers-planet-titanium-atmosphere
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-- Andy.Latto@pobox.com
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
-- Andy.Latto@pobox.com
This was converted from 37.0 Celsius.
In Carl August Wunderlich's 1871 "On the Temperature in Diseases" he devotes chapter 5 to "On the Temerature in Health". There is much here on the variation under sundry circumstances but I'll quote a relevant paragraph (page 82): "The untrustworthiness of the observations of healthy temperature, owing to the difficulty of excluding previously existing slight, or (although latent) serious disturbances of health in the subjects of experiment, and the impossibility of sharply severing pathological effects from physiological ones, prevent our positively determining the *range of temperature in healthy human beings*; yet we may accept, as not far from absolute truth (supported as it is by the numerous observations we have the opportunity of making in convalescence), the statement that the *range of normal temperature in the axilla* is from 97.25º Fahr. (36.25º C.) to 99.5º Fahr. (37.5º C.) *and that the mean normal temperature* = 98.6º F. (37º C.)." Note the mixed use of degree of accuracy and (in this instance) the predominance of the Fahrenheit scale. The work is available from Google as a free ebook.
participants (3)
-
Andy Latto -
Hans Havermann -
Leo Broukhis