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Comment Re:1:1 (Score 3, Interesting) 582

Alas, your proof by calculus is flawed. You said (several layers up):

just take the limit of x/x as x-> 0, it's one. so 0:0 is the same as 1:1

The problem is you could also take the limit of x^2/x or x/x^2 as x->0, and get 0/0 is 0 (for the first one) or undefined (for the second). You could get any number: just take the limit of c*x/x as x->0 to get c.

Notice that the limit of x/x^2 as x->0 is NOT infinity. The limit from the right (that is, restricted to x>0) is infinity, while the limit from the left (x<0) is -infinity. What we really mean by ``the limit is infinity'' is that the function grows without bound. Start treating infinity like a number and things get much more complicated (the rules of algebra start needing exceptions, for example).

IAAM and I'm coming off a semester of explaining calc one to students (and preparing to do it again in the spring term as well).

Comment Re:generally you're not geniuses (Score 3, Insightful) 241

and you've had a happy lives. the people he describes are 1) smarter than you or 2) had it tough emotionally

1) you don't know me, and 2) I'm sorry for them.

I've worked or studied at a variety of places: large state schools, smaller private schools, and in between. I've worked at one of the top five math departments in the country. I've met a lot of mathematicians, from ordinary to world-class. This is just to give you an idea where I'm coming from.

Why do you think people who are smart or good at math must be emotionally or socially troubled?

The original poster said:

This is a universal affliction among mathematicians I've known.

I'm just trying to provide a different perspective.

Comment Re:not quite that (Score 5, Informative) 241

A famous Chinese mathematician, Shing-Tung Yao, was accused of promoting the Cao-Zhu article as the real proof, and taking away credit rightfully due to Perelman.

Yau (the mathematician, not Yao the NBA player) is, of course, the chair of the Harvard Math Department. He is a phenomenal mathematician in his own right (Fields medalist, MacArthur genius grant recipient, etc).

I'm roughly familiar with the controversy, and I think it comes down to: what does it mean to prove something? Perelman provided what for most in the field was an outline of a proof, and Cao-Zhu (among others) dotted the is and crossed the ts. Of course Perelman would say it was a complete proof, and supporters of others would say these others provided valuable details. I think Perelman worked out all the details, but he only shared what he felt was necessary.

Comment Re:Mathematicians (Score 5, Interesting) 241

I'm a mathematician, and I'm afraid I really don't know what you're talking about.

Mathematics is often pictured as a very isolated practice -- a person sitting alone at a desk. But it's surprisingly social, and while there is a fair amount of desk time, there's a lot of interpersonal relationships (as you put it) in the actual doing of math. Asking questions, explaining your results, mentoring students, even teaching classes -- a lot of math involves other people.

Anyway, I know lots of mathematicians, and I think generally they're pretty happy people.

Science

94 New Species Described By CA Academy of Sciences 52

An anonymous reader writes "Researchers at the California Academy of Sciences traversed four continents and two oceans to uncover 94 new species in 2009, proving that while sometimes in this digital age the world can feel like a small place, much of it has yet to be explored. Among the 94 discoveries were 65 arthropods, 14 plants, 8 fishes, 5 sea slugs, one coral, and one fossil mammal. Why does it matter? As Dr. David Mindell, Dean of Science and Research Collections at the Academy, explained, 'Humans rely on healthy ecosystems, made up of organisms and their environments. Creating a comprehensive inventory of life on our planet is critical for understanding and managing resources. Yet a great many life-forms remain to be discovered and described.'"

Comment Re:Deathly! (Score 1) 423

Me too. That is: professor in the northeast, many students with H1N1. The university either puts them in quarantine or sends them home (and it's mostly quarantine because home is usually not close). From my sample (N=400, since I'm in charge of homework scores for a couple of courses), the infection rate seems to have slowed.

Comment Re:Obligatory XKCD (Score 1) 367

M-x butterfly

Knowing emacs, to actually issue that command, you would have to press all those buttons at once.

Well, no. This means "Meta-x" (which for me is esc then x) then type the command butterfly. I guess “Knowing emacs” mean “having heard all the same tired old jokes about that editor I don't use.”

Me? When I went back to grad school (early 90s), I was pleased to find I could use the same old editor I used to use in college (in the mid 80s). I still do all my work in it (used it this afternoon, and on my netbook on the bus in this morning). And version 23 is out!

Comment Re:I wish Python were like TeX (Score 1) 321

I wish Guido van Rossum took a hint from Donald Ervin Knuth (a guy whose name is an anagram for "hunt, drink, and love" cannot be all bad...) and TeX and would create a traditional Python with all the excellent features the language had until version 2.5. My suggestion: call it version 2.718281828459045...

Knuth already beat Python to it. Just as TeX's version is asymptotically approaching , so is Metafont's version is approaching e. I think we need more well-known constants.

(I was going to push for the Euler-Mascheroni constant, but that's =0.57721...., so it would have to be something in eternal beta. And all those Google tools are finally losing their beta tags....

Comment Re:Alternative theory....(and more probable) (Score 5, Informative) 324

It's a good alternate theory, but you're a week off:

On the week ending June 19, Goldman, for instance, was ranked first on the NYSE program trading list. But on the week of June 22, Goldman mysteriously didnâ(TM)t appear on the list of the top 15 firms at all.

So unless the Fourth of July is celebrated in June, I think that's not the issue.

Of course, I'm not checking the volume of trading either, so there could be something to your theory. (Of course, if GS bailed out for a week, wouldn't that lower the volume significantly? Weren't they the number one traders?)

Portables

7-inch Android Netbook From GNB 150

An anonymous reader writes "Netbooknews.com has scored a video of a 7-inch Google Android netbook from a company called GNB during Computex. The device is powered by a Freescale iMX31 CPU. The design might not be to everyone's taste, but it could turn out to be a super cheap Android netbook."

Comment Re:Time Travel... again (Score 2, Interesting) 592

Here's the choice quote I always think of when I hear Vonnegut and science fiction in the same sentence: "I have been a soreheaded occupant of a file drawer labeled 'science fiction' ever since, and I would like out, particularly since so many serious critics regularly mistake the drawer for a urinal." Found on the web, of course.

The one time I saw the guy speak was a huge disappointment. Either he was senile or hammered.

When I saw him he was wonderful. Probably 25 years ago, definitely not senile, but possibly hammered. Still very funny, though.

Comment Re:Jenny McCarthy (Score 2, Insightful) 1056

This ninth-grade argument crap is insightful?

Read about herd immunity. The point is that vaccines only have to be effective most of the time (someone above quotes 95%, so let me use that for the sake of argument). If a large percentage (say, 95%) of a community is immune to a disease, then it becomes difficult for this disease to spread and it dies off. This means if everyone gets vaccinated, then it only has to work for 19 out of every 20 people.

So what Duradin might be saying is: they do work, but not completely, so the vaccine deniers are endangering everyone.

This is really my perspective: Vaccines are a risk. They are a small risk (and not, I believe, from autism). The risk of the disease to the community is greater than the risk of vaccines. By refusing the vaccines, people benefit from others' immunity (and thus from other people facing the risk of vaccines) without sharing any of the cost. That's selfish.

You might argue that it's not the government's place to force these risks on us all. I see it as we the people accepting the communal risks of vaccines as better than the communal risks of disease.

Comment The Shape of Space (Score 5, Interesting) 630

I highly recommend The Shape of Space by Jeff Weeks. (He's a freelance geometer, something he can afford after winning a MacArthur Genius Grant.) I've used this book a couple of times -- once with bright high school kids and once with bright college freshman -- and even if they don't get everything, just a taste is enough.

It builds on Flatland (which someone mentioned above), but has the advantage of being more modern and not sexist. But very quickly you're learning about Klein bottles, connected sums, and all sorts of topology you typically don't see until you're well into your undergraduate (or grad!) program in math. All aimed at high school kids. Very cool stuff.

Oh, and the big punchline at the end: what is the shape of the universe? At least you'll get a good understanding of the possibilities...

Here's a taste for you from a page related to the book.

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