In Space, Can Anyone Hear You Scream?

iStock/coffeekai
iStock/coffeekai

"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.

What's the Difference Between a Real Estate Agent and a Realtor?

Rawpixel/iStock via Getty Images
Rawpixel/iStock via Getty Images

It’s time to buy or sell a house. You jump online to find a representative who can help you navigate the world of real estate. Some identify as a real estate agent, others are Realtors. (And yes, that’s capitalized. More on that in a moment.) Both list houses for sale and guide buyers through the acquisition process.

Unfortunately, those home-buying catalogs and online listings don’t explain the difference between the two job titles, or the reasons you might want to opt for one over the other. If you’re in the market for a new home, here’s an easy way to understand these two major categories of real estate experts.

A real estate agent is an individual who has been granted a state license to conduct business relating to the purchase, sale, or rental of property. That license is given after the person completes a training course, but the content and duration of that education can vary widely by state. California, for example, requires 135 hours of training, over double that of Virginia (which mandates 60 hours). After passing a written test on both federal and state real estate laws and principles, applicants become licensed to practice as an agent. As of 2018, there were roughly 2 million agents in the United States helping to close deals on 5.34 million existing homes being sold.

A Realtor is a real estate agent of a different stripe. The trademarked term belongs to the National Association of Realtors (NAR), a trade organization founded in 1908. It indicates an agent who has become a member of that organization, has received ethics training, and has agreed to be bound by the group’s code of ethics. Put simply, the code mandates that Realtors perform their duties while putting their client’s interest above their own and avoid exaggeration when describing property characteristics, among other pledges.

“Every Realtor adheres to a strict code of ethics based on professionalism, consumer protection, and the golden rule,” Mantill Williams, vice president of public relations and communication strategy for NAR, tells Mental Floss. “NAR’s Code of Ethics, adopted in 1913, was one of the first codifications of ethical duties adopted by any business group. By becoming a member, you agree to uphold and are held accountable to this code of ethics, which includes obligations to clients, the public, and fellow Realtors.

“For example: When representing a buyer, seller, landlord, tenant, or other client as an agent, Realtors pledge themselves to protect and promote the interests of their client. This obligation to the client is primary, but it does not relieve Realtors of their obligation to treat all parties honestly.”

As of July 2019, there were approximately 1.4 million Realtors practicing in the United States and paying the $150 in dues to NAR annually. While nearly two-thirds are also real estate agents, some are brokers, who took a broker’s license exam after completing training on topics relating to legal issues, taxes, and insurance. Brokers typically need to have been working as a real estate agent for three years before obtaining a broker’s license. One can, of course, be a broker without being a Realtor.

So what does all this mean for you, the consumer? Real estate agents who become Realtors might swear by a Code of Ethics, but is it enforceable? If NAR receives complaints that a member is misrepresenting listings, the violation could lead to their dismissal from the group. An agent, meanwhile, might lose their license only if a crime has been committed. Naturally, any sales agent can perform their duties ethically, but a Realtor is likely to face more accountability—and the consumer more avenues for complaint—if a sale is handled improperly.

Does that mean all Realtors are automatically superior to agents? Not necessarily. Some agents may have more experience than a Realtor or might specialize in one area that fits your needs, like commercial real estate. When choosing a real estate professional, it's a good idea to get recommendations from friends and associates. You can also search for Realtors who have a focus on special consumer groups like military personnel.

While Realtors have a high rate of customer satisfaction—90 percent of homebuyers would recommend their Realtor, according to NAR—it’s best to take time and make a careful choice. Buying a home, after all, is the most expensive thing any of us are ever likely to do.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Has An Element Ever Been Removed From the Periodic Table?

lucadp/iStock via Getty Images
lucadp/iStock via Getty Images

Barry Gehm:

Yes, didymium, or Di. It was discovered by Carl Mosander in 1841, and he named it didymium from the Greek word didymos, meaning twin, because it was almost identical to lanthanum in its properties. In 1879, a French chemist showed that Mosander’s didymium contained samarium as well as an unknown element. In 1885, Carl von Weisbach showed that the unknown element was actually two elements, which he isolated and named praseodidymium and neodidymium (although the di syllable was soon dropped). Ironically, the twin turned out to be twins.

The term didymium filter is still used to refer to welding glasses colored with a mixture of neodymium and praseodymium oxides.

One might cite as other examples various claims to have created/discovered synthetic elements. Probably the best example of this would be masurium (element 43), which a team of German chemists claimed to have discovered in columbium (now known as niobium) ore in 1925. The claim was controversial and other workers could not replicate it, but some literature from the period does list it among the elements.

In 1936, Emilio Segrè and Carlo Perrier isolated element 43 from molybdenum foil that had been used in a cyclotron; they named it technetium. Even the longest-lived isotopes of technetium have a short half-life by geological standards (millions of years) and it has only ever been found naturally in minute traces as a product of spontaneous uranium fission. For this reason, the original claim of discovery (as masurium) is almost universally regarded as erroneous.

As far as I know, in none of these cases with synthetic elements has anyone actually produced a quantity of the element that one could see and weigh that later turned out not to be an element, in contrast to the case with didymium. (In the case of masurium, for instance, the only evidence of its existence was a faint x-ray signal at a specific wavelength.)

This post originally appeared on Quora. Click here to view.

SECTIONS

arrow
LIVE SMARTER