April 2012 - mathfun@mailman.xmission.com

[math-fun] Cheshire Cat Dark Matter
by Warren Smith 18 Apr '12

18 Apr '12

The universe is supposedly 4.6% ordinary matter, 22.7% unknown "dark matter" (not made of known particles), and the rest is Einstein's cosmical constant. However, this study of stellar motions in our galaxy claims the dark matter is not present in our region of the galaxy. How can this incredible discrepancy be explained? I have no idea... (Not as easy to see how they could have made such a huge mistake, unlike the "faster than light neutrinos" case...): http://www.sciencedaily.com/releases/2012/04/120418111923.htm -- Warren D. Smith http://RangeVoting.org

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Re: [math-fun] THW (Theophilus Harding Willcocks), is 100 today, Happy Birthday!
by Stuart Anderson 18 Apr '12

18 Apr '12

And if he lives another decade to 2022, his age will equal the size of his discovery in 1978 (110B; 22 squares with a side of 110 - also the smallest possible side in a perfect squared square!) On Thu, Apr 19, 2012 at 2:59 AM, <math-fun-request(a)mailman.xmission.com>wrote: > Send math-fun mailing list submissions to > math-fun(a)mailman.xmission.com > > To subscribe or unsubscribe via the World Wide Web, visit > http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun > or, via email, send a message with subject or body 'help' to > math-fun-request(a)mailman.xmission.com > > You can reach the person managing the list at > math-fun-owner(a)mailman.xmission.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of math-fun digest..." > > > Today's Topics: > > 1. superstring theory solves math problems? (Warren Smith) > 2. n and n^3 have all digits odd (James Buddenhagen) > 3. Re: n and n^3 have all digits odd (Charles Greathouse) > 4. Re: n and n^3 have all digits odd (Hans Havermann) > 5. THW (Theophilus Harding Willcocks), is 100 today, Happy > Birthday! (Stuart Anderson) > 6. Re: n and n^3 have all digits odd (Charles Greathouse) > 7. Re: THW (Theophilus Harding Willcocks), is 100 today, Happy > Birthday! (Henry Baker) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 17 Apr 2012 15:38:06 -0400 > From: Warren Smith <warren.wds(a)gmail.com> > To: math-fun <math-fun(a)mailman.xmission.com> > Subject: [math-fun] superstring theory solves math problems? > Message-ID: > <CAAJP7Y0WF7bZOw=nez3k85mJhZ03+RRjs3R_uqZqcP9kJt4NRg(a)mail.gmail.com > > > Content-Type: text/plain; charset=ISO-8859-1 > > > http://www.ams.org/journals/bull/2000-37-04/S0273-0979-00-00875-2/S0273-097… > > describes a remarkable conjectured formula (arising from generating > functions > ad series reversions) for the number of > rational curves of degree d on a generic "quintic threefold." > The formula gives the right answers for the first 9 cases. > However, it is not even clear that the numbers it outputs, are > always integers, although hundreds have been computed and always came > out integer. > > > > ------------------------------ > > Message: 2 > Date: Wed, 18 Apr 2012 10:09:19 -0500 > From: James Buddenhagen <jbuddenh(a)gmail.com> > To: math-fun <math-fun(a)mailman.xmission.com> > Subject: [math-fun] n and n^3 have all digits odd > Message-ID: > <CAL_+dT+MFANb8eH06pnDa4qK7uSVOXOTM7d9oiHBiS51y81v8g(a)mail.gmail.com > > > Content-Type: text/plain; charset=ISO-8859-1 > > Suppose the positive integers n and n^3 both have all digits odd. > Such numbers include 1, 11, 15, 33, 39, 71, 91, 173, 175, 179, 335, > 3337, 5597, 7353. Is this list complete? This sequence is > http://oeis.org/A085597 in OEIS. But there is no key word indicating > that it is a finite sequence. Is this known to be a finite sequence? > > > > ------------------------------ > > Message: 3 > Date: Wed, 18 Apr 2012 11:48:46 -0400 > From: Charles Greathouse <charles.greathouse(a)case.edu> > To: math-fun <math-fun(a)mailman.xmission.com> > Subject: Re: [math-fun] n and n^3 have all digits odd > Message-ID: > <CAAkfSGLkakN5ryKJ5AJbW5hxacryMc5+V8Gq3QmnA+nKjgVhmQ(a)mail.gmail.com > > > Content-Type: text/plain; charset=ISO-8859-1 > > I don't think it has been proven to be finite, though it surely is -- > there are 5^n n-digit numbers with all digits odd, but the 'chance' > that a 3n-digit number has all digits odd is 2^(-3n). (That the last > few digits are OK doesn't matter, asymptotically.) The sum of (5/8)^n > is of course finite. > > Charles Greathouse > Analyst/Programmer > Case Western Reserve University > > On Wed, Apr 18, 2012 at 11:09 AM, James Buddenhagen <jbuddenh(a)gmail.com> > wrote: > > Suppose the positive integers n and n^3 both have all digits odd. > > Such numbers include 1, 11, 15, 33, 39, 71, 91, 173, 175, 179, 335, > > 3337, 5597, 7353. ?Is this list complete? ?This sequence is > > http://oeis.org/A085597 in OEIS. ?But there is no key word indicating > > that it is a finite sequence. ?Is this known to be a finite sequence? > > > > _______________________________________________ > > math-fun mailing list > > math-fun(a)mailman.xmission.com > > http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun > > > > ------------------------------ > > Message: 4 > Date: Wed, 18 Apr 2012 12:17:28 -0400 > From: Hans Havermann <gladhobo(a)teksavvy.com> > To: math-fun <math-fun(a)mailman.xmission.com> > Subject: Re: [math-fun] n and n^3 have all digits odd > Message-ID: <27A146BD-7C0D-4129-B481-00B4FA1B9932(a)teksavvy.com> > Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes > > James Buddenhagen: > > > Is this known to be a finite sequence? > > I think the best we can ever really do with this sort of problem is > conjecture it to be true and provide a large number up to which it is > known to be true. There was another such question brought up recently > on SeqFan asking if 34155 is the only odd number equal to the sum of > its proper divisors greater than (or equal to) its square root. > > > > ------------------------------ > > Message: 5 > Date: Thu, 19 Apr 2012 02:21:12 +1000 > From: Stuart Anderson <stuart.errol.anderson(a)gmail.com> > To: math-fun(a)mailman.xmission.com > Cc: George Jelliss <george.jelliss(a)virgin.net>, Dom Guerin > <nietzscheplayedchess(a)gmail.com>, Sascha Kurz > <sascha.kurz(a)uni-bayreuth.de>, Lorenz Milla <lorenz.milla(a)gmx.net>, > Ed > Pegg Jr <ed(a)mathpuzzle.com>, Steve Johnson > <stevejohnson2(a)verizon.net>, geoffrey morley <ghmorley(a)gmail.com > >, > efriedma(a)stetson.edu, Richard Guy <rkg(a)cpsc.ucalgary.ca> > Subject: [math-fun] THW (Theophilus Harding Willcocks), is 100 today, > Happy Birthday! > Message-ID: > <CA+3-r9NLO45i+tJ3h1=BN5hnLPnoHkjwJ9+QP3miM0jcew1Myg(a)mail.gmail.com > > > Content-Type: text/plain; charset=ISO-8859-1 > > Theophilus Harding Willcocks, squarer of squares and chess enthusiast turns > 100 today, 19th April 2012! > > http://www.squaring.net/history_theory/th_willcocks.html > > http://www.squaring.net > > Stuart Anderson > > > ------------------------------ > > Message: 6 > Date: Wed, 18 Apr 2012 12:31:22 -0400 > From: Charles Greathouse <charles.greathouse(a)case.edu> > To: math-fun <math-fun(a)mailman.xmission.com> > Subject: Re: [math-fun] n and n^3 have all digits odd > Message-ID: > <CAAkfSGL1C=OghNQfOWQ=sqQHpao82eqGFKkaT+z+xhrqO0kJ1g(a)mail.gmail.com > > > Content-Type: text/plain; charset=ISO-8859-1 > > I think there's hope in the case of the 34155 conjecture. There are > powerful techniques available using sigma_{-1} which might be brought > to bear. > > I feel like the 2e11 lower bound could be used to find a narrow range > (2, 2.00...] in which sigma_{-1}(n) must reside, and then... well, I > don't know or else I'd try to prove it myself. But in any case the > odd digit problem looks much less amenable to solution. > > Charles Greathouse > Analyst/Programmer > Case Western Reserve University > > On Wed, Apr 18, 2012 at 12:17 PM, Hans Havermann <gladhobo(a)teksavvy.com> > wrote: > > James Buddenhagen: > > > > > >> Is this known to be a finite sequence? > > > > > > I think the best we can ever really do with this sort of problem is > > conjecture it to be true and provide a large number up to which it is > known > > to be true. There was another such question brought up recently on SeqFan > > asking if 34155 is the only odd number equal to the sum of its proper > > divisors greater than (or equal to) its square root. > > > > > > _______________________________________________ > > math-fun mailing list > > math-fun(a)mailman.xmission.com > > http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun > > > > ------------------------------ > > Message: 7 > Date: Wed, 18 Apr 2012 09:57:45 -0700 > From: Henry Baker <hbaker1(a)pipeline.com> > To: math-fun <math-fun(a)mailman.xmission.com> > Subject: Re: [math-fun] THW (Theophilus Harding Willcocks), is 100 > today, Happy Birthday! > Message-ID: <E1SKYDQ-0004eO-Rs(a)elasmtp-scoter.atl.sa.earthlink.net> > Content-Type: text/plain; charset="us-ascii" > > We look forward to his birthday in 2033 ! > > At 09:21 AM 4/18/2012, you wrote: > >Theophilus Harding Willcocks, squarer of squares and chess enthusiast > turns > >100 today, 19th April 2012! > > > >http://www.squaring.net/history_theory/th_willcocks.html > > > >http://www.squaring.net > > > >Stuart Anderson > > > > > ------------------------------ > > _______________________________________________ > math-fun mailing list > math-fun(a)mailman.xmission.com > http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun > > > End of math-fun Digest, Vol 110, Issue 18 > ***************************************** >

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Re: [math-fun] THW (Theophilus Harding Willcocks), is 100 today, Happy Birthday!
by Henry Baker 18 Apr '12

18 Apr '12

We look forward to his birthday in 2033 ! At 09:21 AM 4/18/2012, you wrote: >Theophilus Harding Willcocks, squarer of squares and chess enthusiast turns >100 today, 19th April 2012! > >http://www.squaring.net/history_theory/th_willcocks.html > >http://www.squaring.net > >Stuart Anderson

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[math-fun] THW (Theophilus Harding Willcocks), is 100 today, Happy Birthday!
by Stuart Anderson 18 Apr '12

18 Apr '12

Theophilus Harding Willcocks, squarer of squares and chess enthusiast turns 100 today, 19th April 2012! http://www.squaring.net/history_theory/th_willcocks.html http://www.squaring.net Stuart Anderson

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[math-fun] icosahedral virus as art
by James Buddenhagen 17 Apr '12

17 Apr '12

http://artdaily.org/index.asp?int_sec=2&int_new=54792

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[math-fun] symmetry is cheap eye candy
by Bill Gosper 17 Apr '12

17 Apr '12

but some cheap candies <http://gosper.org/mandalas.png> are tasty. Julian was fooling with the m parameter (controlling copies around an m-gon) in the Sierpinski Fourier series. --rwg

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[math-fun] Fwd: R.I.P. Tom Rodgers
by rcs＠xmission.com 15 Apr '12

15 Apr '12

via Jeannine Mosely <j9mosely(a)gmail.com>. I've dropped the picture, to respect our 40KB size limit. Contact me or Jeannine for an individual copy. --Rich ------- Date: Tue, 10 Apr 2012 21:25:22 -0400 Subject: Fwd: R.I.P. Tom Rodgers From: Jeannine Mosely <j9mosely(a)gmail.com> To: math-fun <math-fun(a)mailman.xmission.com> Many of you will have received this message already. For those who don't know, Tom was the principal organizer of the bi-annual Gatherings for Gardner. He will be missed. -- Jeannine Mosely ---------- Forwarded message ---------- From: tom rodgers <thomasmrodgers(a)gmail.com> Date: Tue, Apr 10, 2012 at 6:59 PM Subject: R.I.P. Tom Rodgers To: Dearest Friends and Family, Today at 6:12pm , Thomas Malin Rodgers Jr. passed away after a valiant struggle with cancer. He fought like a bear till the very end. We, the family, would like to thank everyone for their thoughts, prayers, and help during his last days. Per Tom's request there will be no funeral service or burial. He is to be cremated with his ashes distributed amongst his family. Please feel free to celebrate Tom's life in your own way as no formal event will occur. In lieu of flowers please consider donating to Tom's passion, The Gathering 4 Gardner foundation. Please send checks payable to "Gathering 4 Gardner, Inc" to the address below. Gathering 4 Gardner C/O Scott Hudson, Secretary-Treasurer 5475 Fulton Industrial Blvd. Atlanta, GA 30336 Please forward this message along as you see fit. Tom had a diversity of friends and interests. If we missed someone we apologize. Thank You, The Rodgers P.S. For your enjoyment we have attached his rarely seen Senior Yearbook photo from 1961.

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[math-fun] Topological quantum computers
by Warren Smith 14 Apr '12

14 Apr '12

http://arxiv.org/pdf/1204.2792v1.pdf is a new solid state experimental physics paper hyped as having made a giant step toward building quantum computers. I have, however, no idea whether they really did what they say (I'm not even sure what that even would mean) and whether we shall get quantum computers as consequence. (Some years ago I once had an email debate with Michael Freedman, fields medalist and major hyper and inventor of "topological quantum computer" concept, and at the time I was arguing his ideas hopeless... it might be interesting to try to resuscitate that argument and see how this new paper affects it...)

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[math-fun] interplanetary microbes: strength of ice, rock
by Warren Smith 14 Apr '12

14 Apr '12

> rwg: >Steel? Ice? I think we're taking too mechanistic a view. At these scales > and energy densities, everything (air, water, crust, impactor) is just fluids > of various densities. --to the extent that is valid, you are already dead. More precisely, your microbes are already dead. Only way you microbes survive is if they are inside a chunk of rock, ice, or whatever, which stays cold and stays solid and act like normal ice, rock acts the whole time.

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[math-fun] ejecta
by Bill Gosper 13 Apr '12

13 Apr '12

Steel? Ice? I think we're taking too mechanistic a view. At these scales and energy densities, everything (air, water, crust, impactor) is just fluids of various densities. Sandia has done some finite element simulations<http://www.sandia.gov/media/comethit.htm>, but seems to have (re?)moved them. The blobbiness is puzzling. They even did Tunguska<http://www.youtube.com/watch?v=Gr7i33UhmC8>. I think if we look around, we'll find F.E. video of an escape speed "rebound jet" poking clean through the atmosphere. --rwg In a Tunguska article think I saw mention of a modest suspected ice impact crater. Maybe we should drill into it? Maybe with Andromeda Strain precautions?

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