31–35 of 35 posts
Submissions like this is the reason I frequent HN! A thorough well written and well researched article that point by point dissects an interesting event and comes to a surprising conclusion. If you come across other articles of this calibre please submit them!
Hm. Poking around[1], drogue/pilot chutes seem to be around 30 inches or 75 centimeters in diameter. I wonder how you'd get a 3cm piece of "gravel" mixed up in that?
[1] http://www.chutingstar.com/skydive/chernis-collapsible-main-...
" It turns out that when the rock size is set to about 3 centimeters in the simulation, it passes the skydiver at 12 seconds. This rock size just happens to have the same terminal velocity as the solution we found by matching the velocity seen in the video. " Hm. Poking around[1], drogue/pilot chutes seem to be around 30 inches or 75 centimeters in diameter. I wonder how you'd get a 3cm piece of "gravel" mixed up in…
The article's discussion of golf balls reads completely opposite to standard well-accepted theory. The author writes: > [The "drag catastrophe"] is when an object is falling so fast that the boundary layer of gas separates off the object and the drag force suddenly drops by a factor of almost 10. The reason why golf balls have dimples is to cause this drag catastrophe to happen at slightly slower speeds, so the ball…
Ah, the term should be "drag crisis":
http://en.wikipedia.org/wiki/Drag_crisis
http://www.ima.umn.edu/~arnold//papers/golf-flight.pdftl;dr: Occam’s Razor demands the simplest explanation and so it probably was a stowaway piece of gravel
I came here to post that it was a great article - except for the needless invocation and anthropomorphization of Occam's Razor. I. It is not clear that a rock falling out is _simpler_ than a meteorite falling out. How exactly is a meteor less simple? Sure, it's rarer and less likely, but it is not simpler. II. A simple explanation of a how an iPhone works is "magic." But we know that's not the case. Our invocation of…
from https://en.wikipedia.org/wiki/Parsimony#Biology (scroll past the bit about evolution):
(quote)
Systematics is the branch of biology that attempts to establish genealogical relationships among organisms. It is also concerned with their classification. There are three primary camps in systematics; cladists, pheneticists, and evolutionary taxonomists. The cladists hold that genealogy alone should determine classification and pheneticists contend that similarity over propinquity of descent is the determining criterion while evolutionary taxonomists say that both genealogy and similarity count in classification.
It is among the cladists that Occam's Razor is to be found, although their term for it is cladistic parsimony. Cladistic parsimony (or maximum parsimony) is a method of phylogenetic inference in the construction of types of phylogenetic trees (more specifically, cladograms). Cladograms are branching, tree-like structures used to represent lines of descent based on one or more evolutionary changes. Cladistic parsimony is used to support the hypotheses that require the fewest evolutionary changes. For some types of tree, it will consistently produce the wrong results regardless of how much data is collected (this is called long branch attraction). For a full treatment of cladistic parsimony, see Elliott Sober's Reconstructing the Past: Parsimony, Evolution, and Inference (1988). For a discussion of both uses of Occam's Razor in biology, see Sober's article "Let's Razor Ockham's Razor" (1990).
Other methods for inferring evolutionary relationships use parsimony in a more traditional way. Likelihood methods for phylogeny use parsimony as they do for all likelihood tests, with hypotheses requiring few differing parameters (i.e., numbers of different rates of character change or different frequencies of character state transitions) being treated as null hypotheses relative to hypotheses requiring many differing parameters. Thus, complex hypotheses must predict data much better than do simple hypotheses before researchers reject the simple hypotheses. Recent advances employ information theory, a close cousin of likelihood, which uses Occam's Razor in the same way.
(end quote)
Of course, if you read the above and maybe follow a few related links from the WP article, you'll see that it's not quite as straight forward as that, Occam's razor / cladistic parsimony isn't always valid in systematics, but it's an indispensable tool because the search space of valid solutions is so huge, they need a kind of heuristic to guide the way to the most scientifically interesting results (this then becomes not about finding the one correct truth, but about deciding which part of the bigger truth to uncover first).