Valentine's Day Themed Content Contest

It looks like the contest has ended. Happy Valentine's Day!

It's February and love is in the air! I decided to launch a Valentine's Day Content Contest inspired by the many other contests by other members.

To enter, please enter a link to your problem/note/wiki in the comments. Add (at most) one image, if you feel like it.
The problem/note/wiki must be related to Physics, Mathematics or Computer Science in some way. Needless to say, it must also relate to the contest theme.
Wikis are not jokes. If you wish to submit a wiki, please do not compromise with the integrity of wiki articles.
We are looking for the best content, not authors. So, you may submit more than one content.
The score of a content will be determined by number of upvotes. Winning entries will be selected with a probability directly proportional to the score of the submission.
The contest ends on February 13, 2015.
Please avoid debating useless stuff on the comments unless absolutely necessary.

Markdown	Appears as
`italics` or `_italics_`	italics
`bold` or `__bold__`	bold
- bulleted - list	bulleted list
1. numbered 2. list	numbered list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1 paragraph 2	paragraph 1 paragraph 2
`[example link](https://brilliant.org)`	example link
`> This is a quote`	This is a quote
# I indented these lines # 4 spaces, and now they show # up as a code block. print "hello world"	# I indented these lines # 4 spaces, and now they show # up as a code block. print "hello world"

Math	Appears as
Remember to wrap math in \( ... \) or \[ ... \] to ensure proper formatting.
`2 \times 3`	\( 2 \times 3 \)
`2^{34}`	\( 2^{34} \)
`a_{i-1}`	\( a_{i-1} \)
`\frac{2}{3}`	\( \frac{2}{3} \)
`\sqrt{2}`	\( \sqrt{2} \)
`\sum_{i=1}^3`	\( \sum_{i=1}^3 \)
`\sin \theta`	\( \sin \theta \)
`\boxed{123}`	\( \boxed{123} \)

Excel in math and science