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Science & Space

The most popular blog posts about science & space on Hacker News. 2,038 posts.

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726

Cheating on a string theory exam

You and your friend have watches which are synchronized to the second, and the proctors are used to him often finishing exams quickly and won't be suspicious if he leaves early. What is the largest value N such that you can guarantee that you answer at least N out of the 23 questions correctly?

730

Elon Musk and the Hyperloop

For a while now there have been tantalizing hints that Elon Musk is at it again. His usual way of approaching a problem is to look at an industry, find some fatal flaw in it, fix that flaw and then leave everybody else in the dust, wondering why they didn’t do what he did. He’s one of the most interesting people on…

743

Why wasn't the steam engine invented earlier? Part II

As I noted in Part I, the general idea of using heat and steam for mechanical work had a long and continuous history back to ancient times. But when we talk of the breakthrough “steam engine” in the eighteenth-century sense, we don’t mean a machine that exploits steam’s expansive, or pushing force. We actually mean a…