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In Space, Can Anyone Hear You Scream?

"In Space, No One Can Hear You Scream." That was the tagline for the movie Alien, Ridley Scott's 1979 sci-fi/horror masterpiece. Released two years earlier, Star Wars allowed us to hear plenty of things in space, like the whine of TIE fighter engines and the explosion of the Death Star.

So which movie is right? How does sound work in space?

Here on Earth, sound travels as mechanical waves transmitted through a solid, liquid or gas medium (like the air in a room, the water in a pool, or the walls in an apartment building). Pluck a guitar string and it vibrates. The vibration of the string pushes against the molecules of air around the string. Those air molecules, in turn, push against other air molecules, which push against still others, creating oscillations of pressure in the air: a sound wave.

Outer space (which, for our purposes here, we will define as the universe beyond Earth's atmosphere and between planets and other stellar bodies) makes a pretty terrible medium for mechanical waves. It's a vacuum, but not a perfect one. Sound can travel through it, but not very effectively. There's plenty of matter in space "“- stars, planets, asteroids, galaxies, cosmic dust, elemental atoms, etc. "“- and it's all separated by vast distances. Even at the densest parts, there's only a few hydrogen and helium atoms in a cubic meter. If you plucked a guitar string in outer space, it would still vibrate and scraps of matter like cosmic dust and gases might be able to propagate sound waves if you got enough of the matter together, but the sound be too weak for our not-that-sensitive ears to hear.

alien-screamSo, Alien has it right; while it's not strictly true that sound waves can't travel through space, it is true that humans would not be able to hear those sounds. Scream all you want, no one is hear you. There are some loopholes in what we'll call "Ridley's Law," though. Among the things you could hear in space are:

"¢ Anyone talking to you via radio. Radio waves can travel through space because they're electromagnetic, not mechanical, and can travel through a vacuum. Once the radio in your spaceship or spacesuit receives the signal, it converts the signal into sound, which travels through the air in your ship or helmet to your ear.

"¢ A bump on the head. If you're floating in space wearing a spacesuit and you hit your head on something (your ship, an asteroid, whatever), the sound waves resulting from the vibration of your helmet and the object you bumped would be able to travel through your helmet and the air inside it to your ear.

If you've got the right tools, you could also see sounds of a black hole. In 2002, NASA's Chandra X-ray Observatory detected a B-flat note coming from a black hole in the Perseus Galaxy Cluster, some 250 million light-years away. The note is 57 octaves below a piano's Middle C. That's far too low for us to hear. NASA didn't hear the note, either -- they saw it as ripples in the cosmic gas surrounding the hole, caused by the squeezing and heating of the gas by the gravitational pressure of the clump of galaxies packed together in the cluste. They determined the pitch by calculating how far apart the ripples were, and how fast they traveled.

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Tips For Baking Perfect Cookies
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Perfect cookies are within your grasp. Just grab your measuring cups and get started. Special thanks to the Institute of Culinary Education.

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Netflix's Most-Binged Shows of 2017, Ranked
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Netflix might know your TV habits better than you do. Recently, the entertainment company's normally tight-lipped number-crunchers looked at user data collected between November 1, 2016 and November 1, 2017 to see which series people were powering through and which ones they were digesting more slowly. By analyzing members’ average daily viewing habits, they were able to determine which programs were more likely to be “binged” (or watched for more than two hours per day) and which were more often “savored” (or watched for less than two hours per day) by viewers.

They found that the highest number of Netflix bingers glutted themselves on the true crime parody American Vandal, followed by the Brazilian sci-fi series 3%, and the drama-mystery 13 Reasons Why. Other shows that had viewers glued to the couch in 2017 included Anne with an E, the Canadian series based on L. M. Montgomery's 1908 novel Anne of Green Gables, and the live-action Archie comics-inspired Riverdale.

In contrast, TV shows that viewers enjoyed more slowly included the Emmy-winning drama The Crown, followed by Big Mouth, Neo Yokio, A Series of Unfortunate Events, GLOW, Friends from College, and Ozark.

There's a dark side to this data, though: While the company isn't around to judge your sweatpants and the chip crumbs stuck to your couch, Netflix is privy to even your most embarrassing viewing habits. The company recently used this info to publicly call out a small group of users who turned their binges into full-fledged benders:

Oh, and if you're the one person in Antarctica binging Shameless, the streaming giant just outed you, too.

Netflix broke down their full findings in the infographic below and, Big Brother vibes aside, the data is pretty fascinating. It even includes survey data on which shows prompted viewers to “Netflix cheat” on their significant others and which shows were enjoyed by the entire family.

Netflix infographic "The Year in Bingeing"
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