Mark Eichenlaub

2,191 reputation

1620

bio	website	arcsecond.wordpress.com
	location	Baltimore, MD
	age	28
visits	member for	2 years, 6 months
	seen	11 hours ago
stats	profile views	273

I'm a physics graduate student.

	2,191 reputation	bio	website	arcsecond.wordpress.com	visits	member for	2 years, 6 months
1620 badges		location	Baltimore, MD		seen	11 hours ago

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Mar 5	comment	Good Physical Demonstrations of Abstract Mathematics Here's a blog post I wrote a while ago about proving Vieta's formula with basic physics: arcsecond.wordpress.com/2010/09/17/…
Feb 24	accepted	Why is Euclidean geometry scale-invariant?
Feb 23	comment	Prove that Honeycomb Structures are the Most Geometrically Efficient Structure not really physics that I can tell. probably belongs in math.stackexchange
Feb 23	awarded	Commentator
Feb 22	awarded	Nice Question
Feb 21	comment	Why is Euclidean geometry scale-invariant? Interesting point. Then all I need to do is understand how why the Pythagorean theorem is special to Euclidean geometry. The most famous proofs that pop to mind for me involve things like similar triangles, though, and so using them would be circular reasoning.
Feb 21	comment	Why is Euclidean geometry scale-invariant? @Qiaochu I know some linear algebra and a little abstract algebra from studying physics, so yes a more modern treatment would be interesting, but depending on what tools it uses I might need a reference to understand the background.
Feb 21	asked	Why is Euclidean geometry scale-invariant?
Feb 21	awarded	Editor
Feb 21	revised	How to find the distance between a point and line joining two points on a sphere? changed "C" to "X" to fit with picture
Feb 21	suggested	suggested edit on How to find the distance between a point and line joining two points on a sphere?
Feb 17	comment	Derivation of Fourier Series? This isn't really a physics question. I'll flag for the mods to migrate it to math.stackexchange.
Feb 3	accepted	How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers?
Feb 3	comment	How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers? @wok, @Moron Thank you for the links. I saw that post before asking the question, but once I realized it was answering a slightly different question, I didn't read it in detail. I guess I should have.
Feb 3	comment	How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers? Yes, I get in now. The answer is just ${}_{n-r+1}C_r$. Thank you encouraging me rather than giving it away.
Feb 2	comment	How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers? Nice and simple. Thank you.
Feb 2	comment	How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers? @Moron Yes, I did search this site. I found someone talking about non-consecutive birthdays, but that's sampling with replacement, and this is without replacement. Did I miss something?
Feb 2	asked	How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers?
Jan 24	accepted	Why isn't the gamma function defined so that $\Gamma(n) = n! $?
Jan 20	comment	Why isn't the gamma function defined so that $\Gamma(n) = n! $? @Nate Thanks for the link. I checked Wikipedia and the archives on this site, but didn't look at MathOverflow.