January 2013 - mathfun@mailman.xmission.com

[math-fun] Happy New Year
by rtwainwright＠optonline.net 06 Jan '13

06 Jan '13

4, 3, 2, 1, 0.!!! The expression above shows a countdown for the New Year. Using ALL of the thirteen symbols (substituting parentheses for the commas), rearrange them to form a mathematical expression which equals 2013. Any number of the basic arithmetic operations [+, -, x, /] may be used. R. Wainwright

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Re: [math-fun] math-fun Digest, Vol 119, Issue 4
by Robert Munafo 06 Jan '13

06 Jan '13

On 1/6/13, Mike Stay <metaweta(a)gmail.com> wrote: > [huge amount of stuff deleted ...] >> Oops, sorry. http://gosper.org/What%20Don%27t%20You%20Understand.JPG >> --rwg > > Ah, sorry; I missed that response. Yes, I also missed RWG's "Oops, sorry <link>" because it was so darn small compared to all the rest of the quoted message. Please people, if the useful information is so terse, you should either top-post (which I prefer, but is maligned), or actually spend time to edit your replies: > Date: Sat, 5 Jan 2013 15:12:05 -0800 > From: Bill Gosper <billgosper(a)gmail.com> > To: math-fun(a)mailman.xmission.com > Subject: Re: [math-fun] psycho or cyclotron? > > Carolyn Bickford > snappedhttps://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=97… > 14c7&view=att&th=13c0c986320358ba&attid=0.1&disp=inline&safe=1&zw&saduie > =AG9B_P8lFpiS2fxhRBd9EkgD8BAa&sadet=1357421574896&sads=v7R- > qbRkRHRKhLdsM > 2kTA7HeZrM&sadssc=1 > in the Lawrence Hall of Science gift shop. > > > How do you get to it -- when I click on the link I get to a google login > page [I don't have any google accts]. > > /Bernie\ > ---- > Oops, sorry. http://gosper.org/What%20Don%27t%20You%20Understand.JPG > --rwg > _______________________________________________ > 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 4
by Mike Stay 06 Jan '13

06 Jan '13

On Sat, Jan 5, 2013 at 3:12 PM, <math-fun-request(a)mailman.xmission.com> wrote: > Date: Sat, 5 Jan 2013 15:12:05 -0800 > From: Bill Gosper <billgosper(a)gmail.com> > To: math-fun(a)mailman.xmission.com > Subject: Re: [math-fun] psycho or cyclotron? > Message-ID: > <CAA-4O0EgQzmk2GZ3iEc-qjOnWRmYg9zSzTbgXqMu9x1bfWZLQg(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Carolyn Bickford > snappedhttps://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=97… > 14c7&view=att&th=13c0c986320358ba&attid=0.1&disp=inline&safe=1&zw&saduie > =AG9B_P8lFpiS2fxhRBd9EkgD8BAa&sadet=1357421574896&sads=v7R-qbRkRHRKhLdsM > 2kTA7HeZrM&sadssc=1 > in the Lawrence Hall of Science gift shop. > > > How do you get to it -- when I click on the link I get to a google login > page [I don't have any google accts]. > > /Bernie\ > ---- > Oops, sorry. http://gosper.org/What%20Don%27t%20You%20Understand.JPG > --rwg Ah, sorry; I missed that response. -- Mike Stay - metaweta(a)gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com

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Re: [math-fun] psycho or cyclotron
by Mike Stay 06 Jan '13

06 Jan '13

On Sat, Jan 5, 2013 at 3:12 PM, <math-fun-request(a)mailman.xmission.com> wrote: > Date: Sat, 5 Jan 2013 13:44:42 -0800 > From: Bill Gosper <billgosper(a)gmail.com> > To: math-fun(a)mailman.xmission.com > Subject: [math-fun] psycho or cyclotron? > Message-ID: > <CAA-4O0FtoOxhHvzNJ=Jm8qPnkjs4cpsFWVWeW2AV5yNz3LWJJg(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Carolyn Bickford snapped > https://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=97b2a014c… > in the Lawrence Hall of Science gift shop. > Any chance it's a legitimate formula for something? Gmail attachment URLs are only visible to the person who received the attachment. You'd need to put the image on your website for us to see it. -- Mike Stay - metaweta(a)gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com

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Re: [math-fun] psycho or cyclotron?
by Bill Gosper 06 Jan '13

06 Jan '13

Carolyn Bickford snappedhttps://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=97… 14c7&view=att&th=13c0c986320358ba&attid=0.1&disp=inline&safe=1&zw&saduie =AG9B_P8lFpiS2fxhRBd9EkgD8BAa&sadet=1357421574896&sads=v7R-qbRkRHRKhLdsM 2kTA7HeZrM&sadssc=1 in the Lawrence Hall of Science gift shop. How do you get to it -- when I click on the link I get to a google login page [I don't have any google accts]. /Bernie\ ---- Oops, sorry. http://gosper.org/What%20Don%27t%20You%20Understand.JPG --rwg

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[math-fun] Fluid dynamics (was Re: psycho or cyclotron?)
by Robert Munafo 05 Jan '13

05 Jan '13

On 1/5/13, Bill Gosper <billgosper(a)gmail.com> wrote: > Oops, sorry. http://gosper.org/What%20Don%27t%20You%20Understand.JPG > --rwg Thanks Bill! These sites selling the shirt: http://www.scientificsonline.com/what-part-of-t-shirt-10471.html http://lawrencehallofscience.stores.yahoo.net/whatparoftsh.html each identify it as "Navier-Stokes star gas equation". This site: http://www.catstees.com/s4order.htm says "... this is the formula for rocket fuel." It's also being sold at CalTech (start at www.bookstore.caltech.edu and use their search box to search for "What part of") My humble search skills aren't finding any sure proof, but I found a discussion: http://boards.straightdope.com/sdmb/showthread.php?t=371315 which gave a bunch of leads, including one comment that says, "I emailed the t-shirt site to the local college astronomy professor and he confirmed that it's the Navier-Stokes star gas equation," and also this: -- quote -- Its an integral for a fluid control volume problem. Basically, it is if you stood in a river and watched a glob of fluid go by and you wanted to know the net force on that glob. To do that problem you define an imaginary boundry that encloses the fluid The first integral term is the compression of the fluid in question. I forget exactly what beta is defined as, but it relates to the Volume/Surface Area. Doing that integral returns the net force on a control volume due to expansion/compression of the fluid. The second integral is calculating the net force on a moving, rotating reference frame in a fixed reference frame. Its basically a bunch of math stuff, which the derivation of I don't want to go into. As a tid bit, the 2*w*V_xyz term is what is commonly known as the coriolis effect. The third integral is a surface integral that comes from the bernoulli equation applied accross the control surface. I am not sure, but it appears that this part of the equation is wrong. Instead of V_xyz, I believe it should be V_xyz^2/2. The last term is an integral that accounts for the change in momentum (remember that change in momentum/change in time equals force) of the fluid inside the control volume. This is basically the most scary and unweildy equation you could think of for a Mechanical Engineer. [...] -- end quote -- Also, in my searches I found a couple of equations in the "Integral Momentum Theorem" and "Comments on Rocket Equation Derivation and Examples" documents on this syllabus: http://my.fit.edu/~dkirk/4262/Lectures/ that look suspiciously similar. -- Robert Munafo -- mrob.com Follow me at: gplus.to/mrob - fb.com/mrob27 - twitter.com/mrob_27 - mrob27.wordpress.com - youtube.com/user/mrob143 - rilybot.blogspot.com

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[math-fun] psycho or cyclotron?
by Bill Gosper 05 Jan '13

05 Jan '13

Carolyn Bickford snapped https://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=97b2a014c… in the Lawrence Hall of Science gift shop. Any chance it's a legitimate formula for something? --rwg

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Re: [math-fun] psycho or cyclotron?
by Henry Baker 05 Jan '13

05 Jan '13

This content is only available to someone with a gmail account. At 01:44 PM 1/5/2013, Bill Gosper wrote: >Carolyn Bickford snapped >https://mail-attachment.googleusercontent.com/attachment/?ui=2&ik=97b2a014c… >in the Lawrence Hall of Science gift shop. >Any chance it's a legitimate formula for something? >--rwg

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[math-fun] USA Today's fake photo of forming solar system
by Warren Smith 04 Jan '13

04 Jan '13

>From: Phil Carmody <thefatphil(a)yahoo.co.uk> >Anyway, back to: > > http://www.usatoday.com/story/tech/sciencefair/2013/01/02/planet-formation-… It's a lot less remarkable than most paintings I see in the local art galleries near here. You didn't believe USAToday when they credited it "(Photo: M. Kornmesser, ALMA (ESO/NAOJ/NRAO))", did you? It's just an artist's impression, that's all. The actual *photo* is here: http://www.eso.org/public/archives/images/screen/eso1301b.jpg --hmm. The USA Today I got this from said "photo" not "artist impression" and, what really sealed the deal to my gullible mind, was they also gave a VIDEO not just still, which I foolishly thought actually meant it was, like, real data from ESO. Not just an attempt to be even more artistic. But when you think about it, you realize there is no way in hell that star-in-process-of-forming is going to be flying across the background field of fixed stars at that high a rate, so this video was actually a complete fabrication!! That's really really obnoxious to a degree I would have thought unbelievable. Lower my opinion of the press to new lows. The real "photo" which by the way was from radio telescope array, not optical, is not nearly as nice and convincing as the fake. Is it legitimate to draw the conclusion expressed by the fake?

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[math-fun] Sahara Mars meteorite
by Henry Baker 04 Jan '13

04 Jan '13

FYI -- http://www.guardian.co.uk/science/2013/jan/03/mars-meteor-water-sahara-anal… Mars meteorite 'Black Beauty' contains most water of any found on Earth, say scientists Year-long analysis of rock found in Sahara and nicknamed Black Beauty also reveals it is one of the oldest known specimens Associated Press in Los Angeles guardian.co.uk, Friday 4 January 2013 03.20 EST Scientists are excited about a coal-coloured rock from Mars that landed in the Sahara desert. A year-long analysis revealed it is quite different from other Martian meteorites: not only is it older than most, it also contains more water. The baseball-size meteorite, estimated to be 2bn years old, is strikingly similar to the volcanic rocks examined by the Nasa rovers Spirit and Opportunity on the Martian surface. "Here we have a piece of Mars that I can hold in my hands. That's really exciting," said Carl Agee, director of the Institute of Meteoritics and curator at the University of New Mexico who led the study published online on Thursday in the journal Science. Most space rocks that fall to Earth as meteorites come from the asteroid belt, but a number can be traced to the moon and Mars. Scientists believe an asteroid or some other large object struck Mars, dislodging rocks and sending them into space. Occasionally, some plummet through Earth's atmosphere. Short of sending a spacecraft or astronaut to the red planet to haul back rocks, Martian meteorites are the next best thing for scientists seeking to better understand how Earth's neighbour transformed from a tropical environment to a frigid desert. About 65 Martian rocks have been recovered on Earth, mostly in Antarctica or the Sahara. The oldest dates back 4.5bn years to a time when Mars was warmer and wetter. About half a dozen Martian meteorites are 1.3bn years old and the rest are 600m years or younger. The latest meteorite, NWA 7034 Â nicknamed Black Beauty Â was donated to the University of New Mexico by an American who bought it from a Moroccan meteorite dealer last year. Researchers performed a battery of tests on the meteorite and, based on its chemical signature, confirmed it was blasted to Earth from Mars. At 2.1bn years old, it is the second-oldest known Martian meteorite that formed from a volcanic eruption. There is evidence that it was altered by water. Though the amount released during testing at high temperatures was small Â 6,000 parts per million Â it was still much more than other Martian meteorites. Scientists said this suggested there was interaction with water near the surface during a time when the planet was mostly dry and dusty. More tests are under way to determine how long the rock floated in space and how long it had been sitting in the Sahara. University of Alberta meteorite expert Chris Herd, who had no role in the research, said the find was welcome since most Martian rocks that rain on Earth tend to be younger. And the latest find does not appear to be too contaminated, he said. "It's fairly fresh. It hasn't been subjected to a whole lot of weathering," said Herd.

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