September 30, 2016 at 02:38AM

Today I Learned: 1) ...about Valeria Lukyanova, colloquially known as "The Human Barbie". For a while, she dedicated a significant fraction of her life to immitating the physical appearance of a barbie doll. With her body. She did a pretty decent job, too -- through some combination of extreme dieting and possibly surgery (though she denies the surgery bit), she managed to get her proportions about right. She also applies a ridiculous amount of makeup for a pretty spectacular effect. I'm really torn about this case. On the one hand, as a general supporter of transhumanism, I applaud the use of the body for personal expression and the willingness to venture outside human body norms, even for purely aesthetic purpose. On the other hand... of the entire space of possible bodies, she went with *barbie*?!?! That's about the worst possible option I could have thought of. It's kind of pathetic, in my opinion. 2) Simple amplitude modulation (as in, signal encoding) is inefficient in terms of bandwidth. A naïve amplitude modulation scheme will use about twice the bandwidth of the baseband. There are, however, tricks you can use to cut this down. One, whose name I learned earlier today but have forgotten, makes use of symmetry in the Fourier transform of the signal -- since the Fourier of the signal is symmetric around some frequency, you can cut it down by only sending one half of the signal (in frequency space). 3) SSH communication can use public/private key pairs to authenticate a user. Instead of sending a host a password, you can essentially send them proof that it's you with a set of public and private keys you share with the server ahead of time. I don't actually know what the authentication algorithm is, but I imagine it goes something like this: the server sends you a secret, encrypted with the server's private key; you decrypt with the server's public key, ensuring that the secret came from the server; now you encrypt the secret again with your private key and send it back; the server decrypts with your public key, which you gave it in a previous transaction; if the decrypted secret matches the one it sent out, then it knows it's you and it knows you know it's it, and it begins a handshake protocol to open a secure connection. Today I learned that the above authentication is just that -- authentication. The public/private key pair is *not* used to encrypt any subsequent information -- that's all done the same way as in a password-authenticated session.