2 ms·

spoiler alert, directly quoted from article: >The heads of the twiddled bolts move neither inward nor outward. The situation is comparable to that of a person

spoiler alert, directly quoted from article: >The heads of the twiddled bolts move neither inward nor outward. The situation is comparable to that of a person walking up an escalator at the same rate that it is moving down. - Martin Gardner >I don’t find it an especially helpful analogy. Why is the twiddling of bolts like a person walking up an escalator? the bolts and the up-the-down escalator are a good comparison because if you analyze what happens from one bolt's perspective, and then the other bolt's perspective, one is walking up (in) and the other down (out). (as a nit, I don't like when people breezily "reword" what somebody says while analyzing it: are "comparable", "analogous", and "like" exactly synonymous with one another?)

dmurray 2y ago
On your nit, I think the author's use of language is good. If two things are "comparable", they must be "like" each other in some way. Otherwise they could be contrasted, but never compared. The author's question is equivalent to "in what way are these two bolts equivalent to the person and the escalator?"
SamBam 2y ago
I also found it a useful analogy. Or rather, that was the way I thought of it. First I had to think about what would happen if the top bold, instead of rotating around a bolt, rotated around a band that wrapped straight around the other shaft. It stood to reason that the bolt would move backward away from the band, as the band moved along the spiral. (Whether it moved outward or inward ended up being irrelevant.) Then I went back to it being two bolts, and visualized the movement from the head of each. In one, the other bolt moved clockwise, and in the other, the bolt move counter-clockwise. So it stood to reason that one bolt would want to move away from the other, and the other move towards. So they would stay stationary.

dmurray 2y ago

On your nit, I think the author's use of language is good. If two things are "comparable", they must be "like" each other in some way. Otherwise they could be contrasted, but never compared. The author's question is equivalent to "in what way are these two bolts equivalent to the person and the escalator?"

SamBam 2y ago

I also found it a useful analogy. Or rather, that was the way I thought of it. First I had to think about what would happen if the top bold, instead of rotating around a bolt, rotated around a band that wrapped straight around the other shaft. It stood to reason that the bolt would move backward away from the band, as the band moved along the spiral. (Whether it moved outward or inward ended up being irrelevant.) Then I went back to it being two bolts, and visualized the movement from the head of each. In one, the other bolt moved clockwise, and in the other, the bolt move counter-clockwise. So it stood to reason that one bolt would want to move away from the other, and the other move towards. So they would stay stationary.