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marnixR
Post  Post subject: when absence of evidence becomes evidence of absence  |  Posted: Tue Oct 04, 2016 7:01 pm
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I was recently reading a book on the hypothetical planet Vulcan, which was supposed to explain Mercury's precession until Einstein finally proved that the theory of relativity made the existence of such a planetary body unnecessary

however, the astronomical community had already decided some 20 years prior that the continued failure to find Vulcan did indeed mean that there was nothing to find - the crucial point appears to have come with the solar eclipse of 1878, when no conclusive identification of the putative planet could be made

but what exactly made the astronomical community decide that decennia of tentative but never confirmed sightings, together with a final failure during the solar eclipse, was the final straw ? one factor may have been that Vulcan's main sponsor, Urbain Le Verrier, had died in 1877, and maybe no one felt strongly enough about a hypothetical planet with a very erratic observation history to risk their professional career over it

this case history clearly shows that the scientific community CAN switch from absence of evidence to evidence of absence when some boundary has been crossed - but what exactly makes this type of switch happen ?

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iNow
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Tue Oct 04, 2016 9:03 pm
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When ... given everything else we know ... the evidence SHOULD be there, yet after searching and looking and controlling for all extraneous variables it's still not.

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marnixR
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Tue Oct 04, 2016 9:37 pm
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still, the absence of Vulcan during the eclipse, given the uncertainties of its orbit, could have been explained away by saying that it was in transit in front or behind the sun at the time of the eclipse

it's what conspiracy theorists do - everything that doesn't fit the preconceived idea needs to be countered or explained away
i know that in this case we're talking about proper scientists, but even proper scientists have been known to cling to ideas beyond the point where they should have let go of it - so why, in this instance, did no astronomer continue to champion Vulcan's case
after all, its case might have been weakened but not fatally holed below the waterline
it's just surprising that not a single person of note attempted to revive a dying but not quite dead case

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iNow
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Wed Oct 05, 2016 1:49 pm
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interesting question. maybe they were too busy watching star trek

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Falconer360
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Wed Oct 05, 2016 3:52 pm
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I feel like they were Star Wars fans not Trekkies. :lol:

I too am curious why no one continued to champion the case for Vulcan, I mean we still have people claiming a flat Earth or in aether.

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marnixR
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Wed Oct 05, 2016 7:39 pm
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Falconer360 wrote:
... I mean we still have people claiming a flat Earth or in aether.


but no scientists, surely ?

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shlunka
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Wed Oct 05, 2016 9:03 pm

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marnixR wrote:
Falconer360 wrote:
... I mean we still have people claiming a flat Earth or in aether.


but no scientists, surely ?

No scientists, no. We pushed them off.

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Falconer360
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Wed Oct 05, 2016 9:41 pm
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marnixR wrote:
Falconer360 wrote:
... I mean we still have people claiming a flat Earth or in aether.


but no scientists, surely ?

Oh I wouldn't be surprised if there were. I once met a geologist (He had his Master's degree in geology) who still believed in Noah's flood and a 6,000 year old Earth. He worked for a mining company. To me those two things seem to conflict completely, but he had just convinced himself that radiometric dating was a sham and whatever else that was needed was wrong.

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Dywyddyr
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 1:22 am
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Didn't we have a scientist (specialism unknown) on the now dead forum pushing for a flat Earth just before it went down?


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marnixR
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 7:35 am
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seriously, or as a joke ?

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Dywyddyr
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 10:43 am
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He was entirely serious.
According to him experiments he'd performed on Lake Balaton showed that the entire 80 km length was flat, and thus, by extension so is the Earth...


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Falconer360
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 2:59 pm
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Dywyddyr wrote:
He was entirely serious.
According to him experiments he'd performed on Lake Balaton showed that the entire 80 km length was flat, and thus, by extension so is the Earth...

I recall seeing his posts and thinking that I didn't have the patience to deal with him.

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marnixR
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 3:04 pm
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so he didn't know about Alfred Russel Wallace's measurements carried out in East Anglia, where he proved the earth's curvature on a long stretch of straight canal there (see Bedford Level experiment on Wikipedia) - after all, he WAS a qualified surveyor

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PhDemon
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 3:05 pm

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Dywyddyr wrote:
He was entirely serious.
According to him experiments he'd performed on Lake Balaton showed that the entire 80 km length was flat, and thus, by extension so is the Earth...



Ah yes... He was quite "special" wasn't he...

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iNow
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 9:04 pm
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The first ~15mins of this video does a really solid job of explaining away flat earth denialism



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marnixR
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 9:13 pm
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that's as may be but it doesn't address the OP's concern, which is why at times scientists desert a favoured hypothesis in droves long before the definite refutation is made

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Falconer360
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Thu Oct 06, 2016 9:42 pm
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marnixR wrote:
that's as may be but it doesn't address the OP's concern, which is why at times scientists desert a favoured hypothesis in droves long before the definite refutation is made

Peer pressure? Mob mentality? Fear of losing funding because of supporting an unfavorable hypothesis? Some of all of the above? I honestly don't know.

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iNow
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Fri Oct 07, 2016 12:25 am
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What if there is no reason? Maybe it's just chance...coincidence as it were

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marnixR
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Fri Oct 07, 2016 6:53 am
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what bugs me about it is that it goes counter to other times where a paradigm shift happens
e.g. Wegener's continental drift was waiting in the wings for quite some time before it replaced the static earth paradigm

in the case of Vulcan the reason of Mercury's precession did not even have an attempt at an explanation between 1878 (when the astronomical community gave up on Vulcan) and 1915 (when Einstein came up with his relativity-inspired solution)

this is such an odd deviation of what normally happens in science where multiple hypotheses usually battle it out for dominance (until the matter is settled to most people's satisfaction anyway) - I wonder whether most people thought that Newton's theory of gravitation worked so well in most other cases that they were not inclined to throw away the baby with the bath water for a single unexplained anomaly

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marnixR
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Fri Oct 07, 2016 6:42 pm
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been thinking this through for a while and i think i've come up with a solution that i find satisfactory as an explanation

what it boils to was that astronomers couldn't marry two things they thought they knew for certain : they were pretty certain that Vulcan did not exist, whereas they were equally sure that Newton's law of gravity works fine - hence Mercury's precession becomes an enigma that appeared not to have a solution, that is, until Einstein did some out-of-the-box thinking and showed that Newton was not quite as right as the earlier generations had thought

that reminds me a bit of the contradiction that currently exist between relativity, which has been proven to be correct in certain tests, and quantum mechanics, which also has been proven to be correct in other tests - the main problem being that the two can't be reconciled

no doubt some future Einstein will come up with a solution which shows that the current paradox is merely because the current setting of the problem needs to be rephrased

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iNow
Post  Post subject: Re: when absence of evidence becomes evidence of absence  |  Posted: Fri Oct 07, 2016 7:00 pm
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That resonates with me, too. I like your suggestion

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