"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.
So, 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.
If you’ve already mastered DIY houses for birds and dogs, maybe it’s time you built one for yourself.
As Simplemost reports, there are a number of house kits that you can order on Amazon, and the Allwood Avalon Cabin Kit is one of the quaintest—and, at $32,990, most affordable—options. The 540-square-foot structure has enough space for a kitchen, a bathroom, a bedroom, and a sitting room—and there’s an additional 218-square-foot loft with the potential to be the coziest reading nook of all time.
The construction process might not be a great idea for someone who’s never picked up a hammer, but you don’t need an architectural degree to tackle it. Step-by-step instructions and all materials are included, so it’s a little like a high-level IKEA project. According to the Amazon listing, it takes two adults about a week to complete. Since the Nordic wood walls are reinforced with steel rods, the house can withstand winds up to 120 mph, and you can pay an extra $1000 to upgrade from double-glass windows and doors to triple-glass for added fortification.
Though everything you need for the shell of the house comes in the kit, you will need to purchase whatever goes inside it: toilet, shower, sink, stove, insulation, and all other furnishings. You can also customize the blueprint to fit your own plans for the space; maybe, for example, you’re going to use the house as a small event venue, and you’d rather have two or three large, airy rooms and no kitchen or bedroom.
If you asked a few random people to name a situation that wouldn’t be protected under the First Amendment’s “freedom of speech” clause, there’s a pretty good chance at least one of them would mention the example of someone shouting “Fire!” in a crowded theater (when there’s no fire). Over the last century, the scene has been used far and wide to illustrate that if your “free speech” harms people, you can still end up in the defendant’s chair. But, as is so often the case when it comes to interpreting the law, it’s really not that simple.
When people first started discussing human fire alarms at packed gatherings, it was less about constitutional debate and more about societal menace. During the late 18th and early 19th centuries, there were dozens of tragedies [PDF]—mainly in the U.S., but also abroad—where false shouts of “Fire!” provoked panic that resulted in multiple innocent, and avoidable, deaths. In 1913, for example, residents of Calumet, Michigan, held a Christmas party for the children of copper miners on strike. Hundreds of people gathered on the second floor of Italian Hall, and when an unidentified perpetrator (possibly motivated by anti-union sentiments) yelled “Fire!” they all rushed to the stairs. The stampede claimed 73 victims, most of whom were children.
The fear of fire wasn’t unfounded. Since not all buildings had sprinkler systems, neon exit signs, and capacity limits, plenty of fatal blazes occurred. More than 600 people died in Chicago’s Iroquois Theater fire in 1903, event though (ironically) that building was actually thought to be fireproof.
In short, shouting “Fire!” in a crowded theater was an idea firmly entrenched in the public consciousness by the time judges co-opted the phrase for legal arguments on First Amendment rights.
Discussing Fire in a Crowded Courtroom
The axiom became popular in legal spheres after Supreme Court Justice Oliver Wendell Holmes Jr. mentioned it during Schenck v. United States in 1919, but he wasn’t the first person to use it in court. As Carlton F.W. Lawson pointed out in a 2015 article in the William & Mary Bill of Rights Journal, U.S. attorney Edwin Wertz had uttered a lengthier version of it the previous year while prosecuting activist Eugene Debs. In fact, since Holmes ruled on Debs’s appeal the very week after the Schenck case, he may have even gotten the idea from Wertz.
Each case involved a violation of the Espionage Act of 1917, which essentially made it punishable to do anything that interfered with U.S. military operations—including speaking out against the draft. Debs, a pacifist who opposed World War I, was under fire for a speech he had given in Ohio; and Charles T. Schenck, the U.S. Socialist Party’s general secretary, landed in front of the Supreme Court for passing out pamphlets that encouraged men to refuse the draft.
Both defendants were convicted, and Holmes justified his ruling on the Schenck case with the explanation that “the most stringent protection of free speech would not protect a man in falsely shouting ‘fire’ in a theater and causing a panic.” But while his analogy struck an emotional chord, it really had nothing to do with constitutional law.
“The ‘crowded theater’ statement in Schenck never amounted to any kind of binding standard or doctrine,” Nashwa Gewaily, a media and First Amendment lawyer, tells Mental Floss. “It was basically a bit of emotionally charged extra flair from Justice Holmes, outside the official legal determination of that case; a powerful image that endured outside its context ... It was not a high point in American jurisprudence.”
“Revengeance” Is Fine
What Holmes said after it, however, did become a standard for future free speech arguments. “The question in every case,” he said, “is whether the words are used in such circumstances and are of such a nature as to create a clear and present danger that they will bring about the substantive evils that Congress has a right to prevent.”
For the next 50 years, clear and present danger was the accepted—and slightly vague—metric for discerning if spoken or printed material was protected speech. Then, in 1969, the Supreme Court replaced it with something clearer. The case, Brandenburg v. Ohio, concerned a Ku Klux Klan leader named Clarence Brandenburg who had broken Ohio’s law against advocating “crime, sabotage, or unlawful methods of terrorism” for political purposes. (In his offending speech, he had mentioned the possibility of “revengeance” [sic] if the federal government didn’t stop “[suppressing] the white, Caucasian race.”)
Brandenburg appealed his guilty verdict all the way up to the Supreme Court, which overturned the ruling on the grounds that his threats were too ambiguous to “[incite] or [produce] imminent lawless action.” In order for something to qualify as imminent lawless action, it must: expressly advocate violence, advocate immediate violence, and relate to violence likely to occur.
As Gewaily explains, judges interpret this standard “far more narrowly than many would presume.” While individual institutions may condemn hate speech, for example, it’s technically protected under the law unless there’s “immediate violence” involved.
When Free Speech Is the Least of Your Worries
So, does falsely shouting “Fire!” in a crowded theater fall outside the conditions of imminent lawless action, and therefore fall under First Amendment protection? The short answer is that it depends on the circumstances. But here’s the long answer: If you get arrested for doing that, the charges brought against you might make the question of free speech totally irrelevant.
“The falsely shouted warning, while technically speech, could potentially violate a state's criminal laws against disturbing the peace or disorderly conduct, whether or not it provokes a stampede, for instance,” Gewaily says. And if there is a stampede in which somebody dies, you could be charged with involuntary manslaughter. In other words, there’s no law that explicitly prohibits you from crying “Fire” in a theater. It’s the other laws you’d have to worry about.
Shouting “Bomb!” or “Gun!” in public would put you in a similar situation. In May 2018, for example, officials had to evacuate part of Daytona Beach International Airport after a man ran naked through the building screaming about a bomb in the women’s bathroom. There was no bomb, but he was charged with “false report of a bomb,” “criminal mischief,” and “exposure of sexual organs,” among other things. In that case, no self-respecting lawyer would advise him to claim his actions were protected by the First Amendment.
That said, there’s good news for anyone whose panicked cry is an honest mistake. “Someone who shouts a warning in genuine error, with an intent to galvanize movement to safety, would not be properly punished for that speech,” Gewaily says.
And if Oliver Wendell Holmes Jr. has taught us anything, it’s that not every word a Supreme Court Justice says automatically counts as constitutional doctrine.