January 2013 - mathfun@mailman.xmission.com

Re: [math-fun] word wrap...
by Henry Baker 23 Jan '13

23 Jan '13

Sorry, Warren. I'll try to do better nest time. Gosper's emails come through with his _entire message_ as one line, including any quoted stuff from other folks. I don't know why that is, but his are about the only ones that show up like this. At 05:17 PM 1/22/2013, Warren Smith wrote: >>H.Baker: > >--WDS: >(first of all, H.Baker put all the above and more on a SINGLE LINE OF TEXT >with nary a single carriage return. This is impolite.)

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Re: [math-fun] Bzzzz-zappp -- Did the Earth get nuked in 775 AD?
by Adam P. Goucher 23 Jan '13

23 Jan '13

> --WDS: > (first of all, H.Baker put all the above and more on a SINGLE LINE OF TEXT > with nary a single carriage return. This is impolite.) I disagree. It's fairly trivial to select the option 'word wrap' in whatever program you're using to view these messages (even Notepad supports this feature, and that's rather basic), which causes long unbroken lines of continuous text such as this one to be partitioned into multiple horizontal lines, each of which is less than or equal to the width of the space in which you are viewing the aforementioned message. I would argue that using BLOCK CAPITALS to emphasise when you're frustrated at a particular feature of one's writing is at least, if not more, impolite than Henry's practice of leaving massive lines unpunctuated by carriage returns. Again, this leads to more questions than answers: do you prefer the ASCII code 10, 13, or the concatenation of the two? Sincerely, Adam P. Goucher http://cp4space.wordpress.com

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[math-fun] Bzzzz-zappp -- Did the Earth get nuked in 775 AD?
by Warren Smith 23 Jan '13

23 Jan '13

>H.Baker: Yes, this 774-775AD event has been discussed a little by some of us. I believe that this event may have caused a 10C rise in temperature _in one year_, according to Antarctic core data. Or perhaps our "thermometer", which itself depends upon isotope data, was majorly upset by an xray blast. --WDS: (first of all, H.Baker put all the above and more on a SINGLE LINE OF TEXT with nary a single carriage return. This is impolite.) Second, the papers the H-N paper cited re bio-havoc effects of the gamma burst, actually forecast it would cause global *cooling*, not warming, due to NOx causing increased atmosphere opacity. Like I said, I am dubious of all of that analysis. I do not know how a big warming could be forecast -- the direct energy of the burst, equivalent to a few seconds of sunlight, would have essentially zero effect on earth temperature. Anyhow, was there a rise of 10C in 775 AD??? I find that extremely hard to believe, since it would have been noted by observers at the time. If instead Baker is merely claiming oxygen isotope ratios got thrown off in 775AD, then THAT might be compatible with the whole gamma burst hypothesis and is a superb added piece of evidence for it, which you should point out to the authors. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)

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[math-fun] Bzzzz-zappp -- Did the Earth get nuked in 775 AD?
by Warren Smith 23 Jan '13

23 Jan '13

This paper V. V. Hambaryan, R. Neuhaeuser: A Galactic short gamma-ray burst as cause for the 14C peak in AD 774/5 http://arxiv.org/abs/1211.2584 claims in 1 year either 774 or 775 AD, the concentration of carbon 14 increased by an amount equivalent to 14C production in 10 typical years. As detected in tree rings on 2 continents. Also there was a spike in 10Be at the same time (to within time measurement errors). This was the only such spike during the last 3K years. They explain this by postulating there was a gamma ray burst which fried the Earth for 2 seconds with 7*10^17 joules of gamma ray energy. (This is equivalent to the energy of the sunlight hitting the Earth during 4 seconds, but in gamma ray rather than light region of spectrum.) This was presumably caused by e.g. merger of 2 neutron stars at a distance of 3K to 13K lightyears. They think if it had been much closer than that it would have caused notable extinction (of life) events... over, I presume, exactly half of the Earth(?)... which did not happen. I have a problem with this. If you believe them and believe such events happen at least once every 5000 years within 3K to 13K lightyears distance, then it would follow they ought to happen within 1K lightyears at least once every 11M years. Causing big fat extinction events over exactly half the Earth, at that frequency. Which haven't been noticed (have they)?

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Re: [math-fun] Bzzzz-zappp -- Did the Earth get nuked in 775 AD?
by Henry Baker 22 Jan '13

22 Jan '13

Yes, this 774-775AD event has been discussed a little by some of us. I believe that this event may have caused a 10C rise in temperature _in one year_, according to Antarctic core data. Or perhaps our "thermometer", which itself depends upon isotope data, was majorly upset by an xray blast. Even if only 2 seconds long, such a blast would certainly have been noticed by human beings. It might be interesting to try to figure out what part of the Earth was exposed; perhaps that area was thinly populated. While this particular burst seems to have hit the Earth itself, who knows what effects bursts of this type might have on the Sun & its output at other times when the Earth might not have been directly hit. The differential isotope studies are relatively new (< 50 years?) with machines of the precision to detect isotope differences in whole molecules only now coming on-line (e.g., at Caltech), and therefore enormous amounts of data gathering are left to be done. I don't know if any of the NASA probes are capable of such techniques, but we have a huge amount to learn about the relative isotope ratios in different parts of the solar system. For example, it would be interesting to know if such an xray blast hit the Moon, Mars, etc., at the same time. I've heard it said that differential isotope techniques might be useful in determining where (radius from the Sun) and when a planet was formed, so that theories of planet formation & subsequent movement to present orbits can be solidified. At 03:01 PM 1/22/2013, Warren Smith wrote: >This paper > >V. V. Hambaryan, R. Neuhaeuser: >A Galactic short gamma-ray burst as cause for the 14C peak in AD 774/5 >http://arxiv.org/abs/1211.2584 > >claims in 1 year either 774 or 775 AD, the concentration of carbon 14 >increased by an amount equivalent to 14C production in 10 typical years. As detected in tree rings on 2 continents. >Also there was a spike in 10Be at the same time (to within time measurement errors). >This was the only such spike during the last 3K years. > >They explain this by postulating there was a gamma ray burst which >fried the Earth for 2 seconds with 7*10^17 joules of gamma ray energy. >(This is equivalent to the energy of the sunlight hitting the Earth during 4 seconds, >but in gamma ray rather than light region of spectrum.) >This was presumably caused by e.g. merger of 2 neutron stars at a distance >of 3K to 13K lightyears. They think if it had been much closer than that it would >have caused notable extinction (of life) events... over, I presume, >exactly half of the Earth(?)... which did not happen. > >I have a problem with this. If you believe them and believe such events happen >at least once every 5000 years within 3K to 13K lightyears distance, >then it would follow they ought to happen within 1K lightyears at >least once every 11M years. Causing big fat extinction events over >exactly half the Earth, at that frequency. Which haven't been noticed (have they)?

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[math-fun] Exploring the Dark [Matter] Universe
by Henry Baker 22 Jan '13

22 Jan '13

FYI -- very interesting lecture about Dark Matter, which may just be stuff predicted by supersymmetry which is quite plentiful, but which interacts extremely weakly with normal stuff that we can see. In particular, there may be an average of on the order of 1 of these heavy particles per liter of space, but these things move right through us (and the Earth) almost like a neutrino, but much more massive. According to Dr. Arkani-Hamed, exploring the Dark Universe doesn't require higher energy accelerators, since the interactions should happen well within the reach of the accelerators we've had for several decades. The problem is that the interactions with normal matter are 1/1000'th the strength of other interactions, so we just need to look a bit harder/longer. Perhaps we decommissioned some of our older accelerators too quickly ?? This talk is 3 years old, so there must already be some answers to some of the questions he posed. http://online.kitp.ucsb.edu/online/plecture/arkanihamed/ Dec 16, 2009 Exploring the Dark Universe Nima Arkani-Hamed, Institute for Advanced Study There is strong evidence that most of the mass and energy dominating the dynamics of the universe at the largest scales is not made of ordinary matter, but is something newÂ Âdark energyÂ and Âdark matter.Â Understanding the dark sector poses fascinating challenges to theoretical physicists. More excitingly, a slew of experiments ranging from satellites to particle accelerators to deep-underground detectors are poised to shed a great deal of light on this subject in the very near future. In this talk I will describe these developments, and explore what we might learn about the dark universe in the next five years. http://online.kitp.ucsb.edu/download/plecture/arkanihamed/snd/ArkaniHamed_P… (VLC 2.0.5 _can_ play this movie, but you have to set the "file caching" parameter to an absurd value -- around 40 _seconds_ = 40000 msec.)

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[math-fun] Your groan of the day
by Victor Miller 21 Jan '13

21 Jan '13

I poured root beer into a square cup. Now I just have beer.

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Re: [math-fun] How tall can a Lego tower get before the bottom brick is crushed?
by Henry Baker 21 Jan '13

21 Jan '13

FYI -- Perhaps artist Chris Burden would be interested in building a very tall Lego tower. He previously built a 65' tower from stainless steel erector set pieces. Chris Burden is best known in Los Angeles for his outdoor sculpture made of recycled street lights that has become the new symbol of the Los Angeles Museum of Art. http://www.nytimes.com/2008/06/08/nyregion/08rockefeller.html?pagewanted=all An ArtistÂs Vision: Building With Toys, but on a Grand Scale By RANDY KENNEDY Published: June 8, 2008 In the early 1970s, the artist Chris Burden pioneered a kind of sculpture that explored boundaries few people would care even to approach. The basic material was his body, and the work involved what he or others could do with it or to it. The most infamous pieces, ÂShootÂ and ÂTrans-fixed,Â were accurately titled. In one, a friend shot Mr. Burden in the left arm with a .22-caliber long rifle; in the other, he had his hands nailed to the roof of a Volkswagen bug. Sitting at a sunny lunch table near Rockefeller Center recently, Mr. Burden, now 62 and seemingly no worse for the wear, reached into a briefcase and pulled out a piece of raw material for a new work that seemed almost as pliant as a human body. It was part of a thin Erector Set truss, actually a stainless steel replica of one from the original version, which was patented by an architecture-loving toymaker named A. C. Gilbert in 1912. ÂLook how flimsy it is,Â said Mr. Burden, flexing the piece easily between his hands. ÂIt really is just a toy.Â But not far from him, partly shrouded on the trailer of a red Peterbilt truck, sat a sculpture made of hundreds of thousands of such pieces, painstakingly screwed together into a sturdy, almost crystalline creation. In essence, he had transformed a toy inspired by Manhattan buildings into a toy building approaching the size of some real buildings in Manhattan. The work, called ÂWhat My Dad Gave MeÂ Â a 65-foot Erector Set skyscraper, assembled over the last year by Mr. Burden and a team of assistants near Los Angeles Â was hoisted into place early Saturday. It will officially open Wednesday as part of Rockefeller CenterÂs program of monumental outdoor exhibitions presented by the Public Art Fund and Tishman Speyer, which controls the center. In work he has made over the last 25 years, Mr. Burden has been fascinated with feats of engineering as the means by which people try to defy their physical environment, ignoring obstacles like gravity and distance, weight and water. He has built several elaborate, scaled-down bridges using Erector Set and Meccano toy construction parts, including a 28-foot version of the steel-arch Hell Gate Bridge over the East River. (In an article last year, Peter Schjeldahl, an art critic for The New Yorker, described him admiringly as Âa boyish gimcracker diverting us by diverting himself.Â) But Mr. Burden said his obsession with such models sprang from some serious thinking over many years about the nature of toys. ÂTheyÂre the tools we use to inculcate children into how to be adults, how to live in the world,Â he said. ÂBut because theyÂre for children, there is this potential in them thatÂs never realized.Â He gestured back toward the toy skyscraper, which lay on its side on the truck bed in Rockefeller Plaza as two assistants, Joel Searles and Tim Rogenberg, used screwdrivers to attach its spire. ÂI mean, children could have made that, theoretically, but they would never have enough time or parts,Â he said. As early as 1991, Mr. Burden had begun thinking about making a tower-size toy (one drawing from that year shows something he called ÂSmall Skyscraper, Quasi Legal, LA CountyÂ that was never realized). So when Rochelle Steiner, the director of the Public Art Fund, approached him in 2006 in a general way about whether he was interested in making a project for Rockefeller Center Â where his father, an engineer, had once worked Â his answer was not general at all. ÂHe said, ÂAbsolutely, and I know exactly what I want to do,Â Â she recalled. Though he has developed a fairly keen intuitive sense about the amount of weight that Erector Set pieces can bear, Mr. Burden said he had not settled on a height for the toy tower until he visited Rockefeller Center and reminded himself of its scale. ÂAnd I said, ÂHoly cow, this canÂt be a 25-footer,Â Â he said. ÂIt has to be really big.Â He said he felt confident that he could have built to well over 100 feet, or more than 10 stories. But he decided to stop at 65 feet when engineers became involved and wind and stress tests were conducted to ensure that 16,000 pounds of nickel-finished stainless steel would not rain down on Fifth Avenue or a clutch of French tourists. (Asked whether a 100-plus-foot tower would have been safe, Mr. Burden said, smiling: ÂI think it would have been. But failure is very interesting, too.Â) The tower was built in sections at Mr. BurdenÂs studio in Topanga Canyon, and then pieces of it Â including the largest one, the base, which had to be lifted out by helicopter Â were taken to Los Angeles to be assembled. Ms. Steiner, who saw the piece upright during tests before its cross-country truck journey, said she loved it particularly because of the ways it pits the mind and the eye against each other. ÂThe fact that it is both a model and the height of a real building is bizarre,Â she said. ÂIt is simultaneously right and wrong from a traditional building perspective. And so it starts to play tricks on you.Â Mr. Burden, who describes the tower as a poetic interpretation of Rockefeller Center, said he also saw it as saying something about the ambitions of America, which he has always viewed in a slightly idealized way after growing up mostly in France and Italy. ÂI see it as optimistic and positive, though it feels corny to say those things,Â he said. The Erector Set and the skyscrapers that inspired it are emblems of the kind of confidence the country had at the turn of the 20th century, he said. ÂI think we could get it back,Â he added. ÂI donÂt think itÂs impossible.Â In person, Mr. Burden Â a barrel-chested man still built like the wrestler he was in high school Â is personable and funny, making it slightly difficult to imagine him performing the confrontational and at times horrific pieces of his youth. He said he saw his engineering pieces as part of the same tradition. ÂThese are structures that are performing themselves in their forms,Â he said. But by 1975 he had turned away from body-based performance, in part because of the kind of attention it was attracting. ÂIt became very misunderstood,Â he said. ÂI wasnÂt doing it to be some kind of stuntman.Â (He said he bore no physical infirmities from those years; one of his worst injuries came only a few years ago when he wrestled a coyote to the ground after it latched onto his dog. The coyote then latched onto his left hand and almost tore off part of a finger.) As Mr. Burden finished lunch and headed back to his tower, he said he was relieved that the piece made it across the country unscathed. ÂIt required intense concentration to put together Â itÂs really easy to make a mistake, and when you do, you have to take apart what youÂve done and start over,Â he said. ÂIt might look like childÂs play, but itÂs anything but.Â

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Re: [math-fun] readability of math-fun posts
by Adam P. Goucher 20 Jan '13

20 Jan '13

Can't we post simple formulae in the obvious single-line form, and more complicated ones in LaTeX? For instance, something as simple as Stirling's formula could be written assqrt(2 pi n)(n/e)^e, whereas more complicated expressions may be more readable just posted as LaTeX. I don't particularly like the use of white space to position things in a two-dimensional expression, since certain programs render text-only messages as monospaced, whilst others use Times New Roman or whatever. And there's no point drawing an actual Greek letter theta when you can just as easily type 'theta'. That's just deliberately making it awkward for people like Warren who probably still use Internet Explorer 2! Sincerely, Adam P. Goucher http://cp4space.wordpress.com > ----- Original Message ----- > From: Axel Vogt > Sent: 01/19/13 08:53 PM > To: math-fun(a)mailman.xmission.com > Subject: Re: [math-fun] readability of math-fun posts > > > Message: 4 > > Date: Sat, 19 Jan 2013 14:42:51 -0500 > > From: Warren Smith<warren.wds(a)gmail.com> > > To:math-fun@mailman.xmission.com > > Subject: [math-fun] readability of math-fun posts > > Message-ID: > > <CAAJP7Y1+=TqpHOuBbmdTdSVNoHFj83ZJNN882FeSRE6DifcXfw(a)mail.gmail.com> > > Content-Type: text/plain; charset=ISO-8859-1 > > > > --If you stick to plain ASCII character set, then you are safe. If > > you use anything else, > > then some people will have trouble reading it. Sure, we may be able > > to compensate > > if we try hard enough, but I think a post for a general, > > cross-platform audience, ought to > > be designed so Ignorant Joe Schmoe can read it. Another thing some > > posters enjoy doing is making a fairly long message which is all on > > one single line, say 1000 characters long. > > Again, some reader tools insert line breaks to make that readable. > > Others do not. > > I am still too dumb to answer correctly (using Thunderbird as > mailer) into a thread :-( > > But it may be, that for example Bill Gosper (using Google Mail) > may have some setting to provide html mail and/or encoding is not > the prefered one (ISO-8859-1). > > _______________________________________________ > math-fun mailing list > math-fun(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun

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Re: [math-fun] math-fun Digest, Vol 119, Issue 27
by Tom Duff 20 Jan '13

20 Jan '13

James Cloos <cloos(a)jhcloos.com> writes: > >>>>>> "BG" == Bill Gosper <billgosper(a)gmail.com> writes: > > BG> Who else is having this problem? > > Your email comes from the list as text/plain charset=utf-8. > > There is no excuse for any currently-maintained email software to be > unable to handle that, though one does need to have enough fonts (either > just available or explicitly configured, depending on the software) to > cover the characters used. I get the math-fun digest and read it in Alpine, and I see ? (that's a question mark) instead of Γ° (that was a pi.) Alpine has no trouble displaying Γ° (pi again) when I send one to myself. Here is an extract from the email headers of the digest: From: math-fun-request(a)mailman.xmission.com ... Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit ... So it looks like I'm not seeing UTF-8 in the digest because it's not getting sent to me. So another possible culprit is the mailman digestizer. I don't know if the digest character set is a settable option, but if it is, switching it to UTF-8 might fix everyone's problem. -- Tom Duff. At this point, I went back to the literature.

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