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Comment other families of solutions (Score 1) 496

There are other ways of looking at the problem:

"You're standing on the surface of the Earth. You walk one mile south, one mile west, and one mile north. You end up exactly where you started. Where are you?"

Other posters have pointed out that "Where are you?" is ambiguous and could mean a Simon says sort of answer like "I'm in your office, Mr. Musk." And also that it could be taken to mean relative to a Sun-centered coordinate system. This latter requires waiting N years to return to the same part of the Earth's orbit.

Once one notices that no time limit is required you get many more solutions by allowing for the polar motion over some period of time: - that is, the pole isn't in the same place at the end as at the beginning.

Then there's the notion of repeating the exercise at the north and south magnetic poles (and perhaps geomagnetic). But there is also no explicit constraint that south, west and north are all interpreted the same - they need not all be geographic or all magnetic. In that case there are families of solutions near each of the four poles that interpret the initial motion one way and the final mile the other.

And then the magnetic poles wander much more rapidly (several miles per year) than the geographic poles and over much more than the mile allowed (, so you can put constraints on the time period allowed for the exercise while exploring solutions covering motions over a few weeks.

Comment Re:Way to compare apples to light bulbs (Score 1) 200

It is not true that "there have been many, many, many more attempts at Mars than missions that actually got there", see:

Mars exploration splits into two eras, the cold war competition between the U.S. and Soviets - which the U.S. won hands-down, Yay Mariner! Yay Viking! - and the past couple of decades with the U.S. and other countries collaborating in various combinations.

During the cold war the U.S. had a track record of 8 successful missions versus 2 launch failures. During the recent couple of decades we've had 9 successes versus 3 diverse spacecraft failures. And many of those successes have been far beyond mission profiles. So the NASA Mars team is about 17 wins against 5 losses. This would be regarded as stunningly successful in any sport.

The Soviets in the early days had many launch failures that can't really be charged to the Mars missions themselves - and were about the reverse of the U.S. cold war ratio for those that did get to Mars. It was still a remarkable achievement for them to place any one of those missions in orbit.

There have also been about a half dozen non-NASA Mars missions during the past two decades. Two Russian missions unfortunately continued the trend of never leaving LEO. And now India is one-for-one. May they keep it up! Europe is one-for-two and Japan is zero-for-one. Talk about small number statistics, but that's 2 wins / 2 losses. Quite respectable. One hopes other nations join the fun.

In the aggregate this is a remarkable tally of successful missions considering Mars is never closer than 50 million kilometers or so. Anybody know the corresponding statistics for missions in LEO?

Comment The world is not flat (Score 1) 1010

"Political Scientist" is a colossal oxymoron.

Whatever this guy and Thomas Friedmann (and alas! Terry Pratchett) say, the world is not flat. Algebraic equations of degree higher than linear (and even - gasp - other than polynomials entirely) are needed to describe how it works. Algebra is the bare minimum to comprehend how functions work. It is telling that TFA doesn't even mention differential equations - the real basecode of the universe. A grounding in algebra provides the most basic of tools to understand graphical representations of a dynamic multivariate world, even without calculus.

That a political scientist would emphasize "lies, damn lies, and statistics" as the pinnacle of mathematics is unsurprising.

Comment Re:I'm Good Enough, I'm Smart Enough! (Score 1) 1359

It depends on the figure of merit and on the measure of central tendency being applied to it. "Average" can mean different things. If the distribution is skewed, the arithmetic mean will always lie to one side or the other of the median.

Stuart Smalley seems the poster child for Dunning-Kruger and related effects.

Comment Re:Not that much storage (Score 1) 73

Astronomical data are background limited. The noise is as interesting as the signal, and many sources lie beneath the noise and are only visible through coadding. The gain and read-noise of LSST's detectors will be tuned similarly to other astronomical cameras because these parameters are governed by the experimental design.

Lossless Rice compression should be around R of 2-2.5 ( with lossy compression of reduced data products falling between R of 3 to 5 depending on the quantization selected (

There will be no delta frame advantage since the compression is governed entirely by the noise (i.e., entropy) due to the sparse signal in astronomical data and the noise is a combination of gaussian and poisson (shot noise) sources that varies from exposure to exposure.

In fact, a key goal of the project is precisely to look for differences between each frame and a baseline static sky so the differences must be preserved in great detail.

Comment Science is a calling (Score 1) 279

A career in the sciences is far less likely to be touched by fraud than more commercial endeavors. "Follow the money" as they say. Each discipline is its own community, however, and the level of political infighting, the need to struggle for funding, the publication pressures, etc, vary greatly. External pressures are different, too, but condensed matter physics is about as far from the front lines of the culture war as one can get :-) I do wonder what mythical past the recent critics of science (and of academia in general) are comparing us with. Government funding has always been in the mix. Corporate funding has always come with strings attached. Read Neal Stephenson's Baroque Cycle to get a sense for the underlying drama of research as a creative exercise. A good bit of luck is needed to follow the narrow path to tenure. (I stepped off long ago.) A good bit of luck is needed to bubble to the "top" of any organization of any type. The difference with the sciences is that there are innumerable interesting detours and niches along the way. Having a graduate degree in a STEM field is an advantage for pursuing many future options. And the journey has been a hell of a lot of fun! Ultimately the question becomes "compared to what?" How will you put food on the table if you forgo grad school? And is a seat at a smaller table enough for you?

Comment "Culturomics" is not destined for long life... (Score 1) 287

Blame the WSJ for the tropes here about physicists and "culturomics". The lead author of the linked paper is an economist. The WSJ article also mingles information from other publications. On the other hand, Steven Pinker has (rather persuasively) argued for a physical model underlying the structure of language (and not just in English):

Comment Original citation says nothing of the sort (Score 2) 1276

I read through the 4-pointers and didn't see a citation to the original paper. This appears to be it: It has precious little to do with any of the grandiose claims being attributed to it. TFA and the scores of echoed "See? I told you democracy was a scam!" articles are aggressively misconstruing the meaning of this. The paper is a couple of years old and the author appears to have no special expertise in this field.

Comment The article is garbage (Score 3, Insightful) 1276

It's a tradition on slashdot to not read the article, but has anybody of any political persuasion here actually clicked the link? It's a piece of crap designed to be echoed around the internet. So far I've been unable to locate the cited research from either this article or in any of its echoes or by searching directly. The word "smart" is something added to create heat, the phrase used is "leadership skills", and there is no indication how such skills are gauged in either the simulated voters or the simulated candidates. Nor any mention that the voters only get to choose between two starkly different candidates - this is a rather binary decision to simulate. It is insipid to blame the voters for the candidates produced by the major parties.

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