How Many Dimensions Are There?

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iStock

Ask someone to name every dimension they know of and they'll likely list the following: length, width, and depth. They might also add time if they’re thinking outside the three-dimensional box. But asking a string theorist, “How many dimensions are there?” would elicit a very different response. According to this branch of theoretical physics, there are at least 10 dimensions of space, most of which are impossible for humans to perceive.

Dimensions are the metrics that physicists use to describe reality. Sounds broad, right? Let's start with the three dimensions most people learn in grade school. The spatial dimensions—width, height, and depth—are the easiest to visualize. A horizontal line exists in one dimension because it only has length; a square is two-dimensional because it has length and width. Add depth and we get a cube, or a three-dimensional shape.

These three coordinates are used to pinpoint an object's location in space. But space isn’t the only plane we exist on; we also exist in time, which is where the fourth dimension comes in. Once we know a dot's altitude, longitude, latitude, and position in time, we have the tools needed to plot its existence in the universe as we know it.

But some physicists who subscribe to string theory argue there’s more to reality than the observable universe. String theory, also known as "superstring theory," aims to unify two main theories describing how the universe works: general relativity (which applies to very large objects) and quantum mechanics (which applies to very small ones). In a four-dimensional universe, this theory wouldn’t be possible, but once scientists tweaked the math to include 10 dimensions—11 including time—their equations worked.

After coming up with a theory that hinges on the existence of 10 space dimensions, string theorists then had the job of explaining where those new dimensions were hiding. Their answer: They are just as real as the "big" dimensions we can see, but the extra dimensions are curled up so tightly that they're too small for us to notice directly.

Our basic understanding of physics makes this hard to process, but string theorist Brian Greene does a great job of framing the concept in terms most people can understand. In his 2005 TED Talk, Greene compares these invisible dimensions to the cables connected to telephone poles: From a window, a wire looks like a one-dimensional line. But if we were to study it up close we'd see that the cord is actually round, making it three-dimensional. No analogy comparing unobservable dimensions to objects in the observable world can ever be perfect, but this illustrates how something so fundamental to reality could be hiding in plain sight.

String theory states there must be at least 10 dimensions of space plus one dimension for time, but there are physicists who argue that there are more. Some posit a universe composed of 11 space dimensions. But to really blow someone's mind when they ask how many dimensions there are, say 26: That's the magic number according to Bosonic string theory, and it's as high as mainstream physicists are willing to go for the time being.

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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.

Can You Ever Truly Lose Your Accent?

DGLimages, iStock via Getty Images
DGLimages, iStock via Getty Images

You may be able to pull off a Spanish accent when showing off your Antonio Banderas impression, but truly losing your native accent and replacing it with a new one is a lot harder to do. The way you speak now will likely stick with you for life.

According to Smithsonian, our accent develops as early as 6 months old—accents being the pronunciation conventions of a language shaped by factors like region, culture, and class. When a baby is learning the words for nap and dad and play, they're also learning how to pronounce the sounds in those words from the people around them. Newborn brains are wired to recognize and learn languages just from being exposed to them. By the time babies start talking, they know the "right" pronunciations to use for their native language or languages.

As you get older, your innate understanding of foreign accents and languages gets weaker. If you're an English speaker raised in Boston, you may think that the way someone from Dallas speaks English sounds "wrong" without being able to articulate what it is that makes them sound different. This is why pulling off a convincing foreign accent can be so difficult, even if you've heard it many times before.

Around age 18, your ability to learn a second language takes a steep nosedive. The same may be true with your ability to speak in a new accent. If you immerse yourself in a foreign environment for long enough, you may pick up some ticks of the local accent, but totally adopting a non-native accent without making a conscious effort to maintain it is unlikely as an adult.

There is one exception to this rule, and that's Foreign Accent Syndrome. Following a head injury or stroke, some people have reported suddenly speaking in accents they didn't grow up using. The syndrome is incredibly rare, with only 100 people around the world having been diagnosed with it, and medical experts aren't sure why brain injuries cause it. But while patients may be pronouncing their words differently, they aren't exactly using foreign accents in the way most people think of them; the culprit may be subtle changes to muscle movements in the jaw, tongue, lips, and larynx that change the way patients pronounce certain vowels.

[h/t Smithsonian]

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