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Monday, August 6, 2012

Bad Data! Bad!

Started a new fact article for ANALOG entitled "Spanking Bad Data Won't Make Them Behave" about the problems of definition, measurement, sampling, and adjustment of data, illustrated with various personal experiences from my storied youth.

The good news is that it is up to 5000 words already.  The bad news is that the standard limit for such articles is 4000 words.  And I'm not finished yet.  Ah, well.  I must hone me boning knife.  

An excerpt from the first draft:


"A fact has no 'why.'  There it stands, self demonstrating."
– Robert A. Heinlein, "The Year of the Jackpot"
Nothing is more elusive than a fact.  Far from being self-demonstrating, it is meaningless without contextual information.  When did World War II begin?[1]  One hundred and twenty determinations of the speed of light in vacuo have yielded various values.  A few examples:
Year
Experimenter
Method
Speed of Light
1879
Michelson
rotating mirrors
299,910 kps
1882
Michelson
rotating mirrors
299,853 kps[2]
1928
Mittelstaedt and Birge
Kerr cell
299,786 kps
1936
Anderson and Birge
Kerr cell
299, 771 kps
1950
Bergstrand
geodimeter
299,793 kps
1956
Edge
geodimeter
299,792 kps
Notice that not only were different results obtained with different methods, but also in repeat determinations with the same method – and often by the same researcher!  The overall trend was toward slower light speeds (see Fig. 1). 

Figure 1: Trend in measured light speed.  The fitted line is a quadratic regression, added just for slaps and giggles.
There are several possible reasons.  That light is actually slowing down is attractive for us SF types, but unlikely for a number of reasons.[3]  Another could be that successive methods of measurement have been more accurate.  But another reason may not occur to anyone. 
There ain’t no such thing as the speed of light. 
#
When Measurement Goes Bad
Has Flynn lost his flipping mind?  Consider some examples of measurement:  ...........


[1] You probably said Sept. 1939.  But the Pacific war began in July 1937; and the world war as such did not begin until Dec. 1941 merged the European and Pacific wars into one.
[2] Yeah, I know.  Makes you wonder about that aether thingie. 
[3] But see João Magueijo, Faster Than the Speed of Light (Perseus Pub., 2003). 

5 comments:

  1. I like the way you think, sir. And write. This has me fascinated already, and I look forward to seeing more.

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  2. I know you're trying to cut rather than pad, but I am compelled to remind you of Richard Feynman's Cargo Cult Science address, in which he tells the story of Milliken's oil-drop experiment and its later replicators. "Why didn't they discover that the new number was higher right away?
    It's a thing that scientists are ashamed of--this history--because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong--and they would look for and find a reason why something might be wrong. When they got a number closer to Millikan's value they didn't look so hard. And so they eliminated the numbers that were too far off, and did other things like that. We've learned those tricks nowadays, and now we don't have that kind of a disease."

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  3. "There are several possible reasons. That light is actually slowing down is attractive for us SF types, but unlikely for a number of reasons.[3] Another could be that successive methods of measurement have been more accurate. But another reason may not occur to anyone.

    There ain’t no such thing as the speed of light.
    "

    If the "speed of light" were 'infinite', as used to be believed, that would be the same as "There ain’t no such thing as the speed of light", wouldn't it?

    The answer to [n / 'zero' = ?] is the number 'infinity'

    What is the answer to [n / 'infinity' = ?] Is it 'zero'? Is it "whatever number one wishes to choose"?

    If the "speed of light" were 'infinite', and the answer to what is [n / 'infinity'] is "whatever number one wishes to choose", then those two fact may well explain the varying measurements.

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  4. Ah! That sound in the background is the Spirit of W. Edwards Deming, whispering, "By What Method?"

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  5. Regarding the size of the Analog article, I recall a delightfully funny anecdote of Asimov's about delivering the manuscript for ASIMOV'S BIOGRAPHICAL ENCYCLOPEDIA OF SCIENCE AND TECHNOLOGY after it had grown, unbeknown to the editor, to 3 or 4 times the size agreed upon. The anecdote was added to the introduction of the same book before it was published, full size with no cuts. If you have the book, or have access to it, and don't remember reading the introduction, I'd think you'd get a chuckle out of it. Maybe you can make it a 2 part article.

    BTW, I found my way here, because I enjoyed your contributions on climate theory to FALLEN ANGELS (perhaps my favorite SF novel of all times) so much I was trying to find if you have published non fiction of the subject more recently. As far as I can see, the only part of the climate lecture at the con (that Niven writes is mainly your work and your ideas) that doesn't still hold up is that the neutrinos have been found. Last place on ea . . ., well, anywhere, I'd have expected to find them.

    ReplyDelete