"The Goal Is To Get From Point A To Point B As Creatively As Possible So Technically They Are Doing Parkour,

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From the coldest cold to the hottest hot, here’s all the universe’s temperatures.

(from BBC Future)

Bonus question: What is hotter, a boiling tea kettle or an iceberg?

Adding two identical waves, shifted by different amounts, to give a new wave. The waves interfere to either amplify each other, cancel each other out, or something in between. [more] [code]

Having been lucky enough to travel on numerous roads like this last summer, I'm pretty sure I remember being genuinely and irrationally afraid of this exact thing happening. I have no clue why.

Joel Tettamanti - Greenland

Lagrange's theorem

Theorem: The size of a subgroup of finite group is divisible by the group’s size. That is, if H is a subgroup of G, |H| is a divisor of |G|.

Proof: Let’s start by saying we have a group G and a subgroup H.

This proof will count cosets. Specifically, I’ll use left cosets, but right cosets work the same way. Also, this proof will rely on a few properties of the integers.

I’ll prove this through lemmas, which are theorems used to prove other theorems. The distinction between a lemma and a theorem is only based on how we use them, and so historical reasons might leave some theorems as “lemmas.”

Keep reading

These diagrams, made in 1855 by cartographer J. H. Colton, show the relative sizes of islands and lakes around the world.

Iceland’s sublime silence

A Canadian photographer turns her fascination with Iceland into a series celebrating the country’s raw and wondrous landscape