Australian Toilets Don't Flush Backwards Because of the Coriolis Effect

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File under "News to Me": you know that old story about how northern hemisphere toilets flush counter-clockwise, and southern hemisphere toilets (and buckets, drains, and such) flush clockwise, due to the Coriolis effect? It's bogus! Today I learned that while the Coriolis effect is significant for hurricanes, it's not strong enough to make toilets flush in different directions at different points on the Earth. The real cause of "backwards"-flushing toilets is just that the water jets point in the opposite direction. Mind blown. (Mind blown even more because this was the inciting event on a Simpsons episode, and everybody knows cartoons are never wrong.)

Let's Talk Science

So there is indeed a Coriolis effect, and we see it on grand scales -- hurricanes in different hemispheres tend to rotate in different directions, because the underlying Earth is spinning, and the effect is exaggerated as you move farther from the equator. This Penn State science page by Professor of Meteorology Alistair B. Fraser explains:

On the scale of hurricanes and large mid-latitude storms, the Coriolis force causes the air to rotate around a low pressure center in a cyclonic direction. Indeed, the term cyclonic not only means that the fluid (air or water) rotates in the same direction as the underlying Earth, but also that the rotation of the fluid is due to the rotation of the Earth. Thus, the air flowing around a hurricane spins counter-clockwise in the northern hemisphere, and clockwise in the southern hemisphere (as does the Earth, itself). In both hemispheres, this rotation is deemed cyclonic. If the Earth did not rotate, the air would flow directly in towards the low pressure center, but on a spinning Earth, the Coriolis force causes that air to be deviated with the result that it travels around the low pressure center.

So it works on large scales. But on small scales (like in your toilet, sink, or bucket), the rotation of the Earth itself (at a decidedly pokey rate of one rotation per day) is much weaker than other forces -- like the force of water jets in a toilet, or the force of water hitting slopes in a sink.

The Pole to Pole Problem

In tracking down where this drain-direction myth originated and how it got so firmly lodged in the heads of people like me, many sources discuss the (otherwise awesome) Michael Palin documentary Pole to Pole, in which Palin visits the equator in Kenya and observes a tourist trap in which a man "demonstrates" (via fakery) the draining of water in different ways on the equator itself, and just north and south of it. Palin doesn't point out that it's fake. I remember seeing this documentary when it came out, and it may be where I picked up the notion -- it seems like such an appealing demonstration of science, such an "ah-ha!" moment that of course the rotation of the Earth should cause such changes in draining water! We're all tiny ants on a huge spinning globe! What wonders! Sadly, it's BS. Again, Fraser has a good write-up; here's a snippet:

[T]he faker must be forcing the rotation by other means, and by a sufficiently unobtrusive way that the busloads of tourists do not spot the means. Indeed, a colleague of mine, who witnessed the performance first hand and knew it was a cheat, was not able to spot how the fraud was perpetrated. (It is an interesting sidelight that when back on the bus, he informed his fellow tourists that they had just witnessed fakery --- the Earth did not cause the rotation they had just seen --- there was widespread disappointment. The tourists preferred the fantasy to the reality.)

Fraser proceeds to explain how you can fake it yourself.

The Plot Thickens

According to various sources, it is possible to demonstrate a Coriolis effect on water on a small scale, but only under extremely controlled circumstances -- involving predictably shaped water vessels, long periods of time of waiting for water to become as still as possible, carefully removing a stopper in the bottom of the vessel without adding spin, and other such crazy stuff. But in your typical toilet or sink, the Coriolis force is so small as to be undetectable relative to other forces. Even holding a bowl of water and turning around introduces sufficient spin to get things going in one direction or another.

A Fun Experiment

Go to your bathroom now and observe water going down the drain -- any drain you want. Depending on the efficiency of your plumbing, you may need to stop up the drain, fill the basin, then unplug it and wait. (It might also help to have something lightweight floating in there, to mark any motion -- a few bits of tissue may work, or a matchstick or two.) Observe whether the draining water forms a clockwise or counter-clockwise spiral. Go ahead, I'll wait. Now check all the other drains you can find. Do they match? In my (admittedly unscientific) testing just now, one sink drained clockwise, the other counter-clockwise, one didn't have an easily observable spin (it's small), and the toilet was also counter-clockwise, clearly due to the position of its water jets. Well. There you go: science in action.

(Via Steven Frank, via Snopes. Note that we covered this topic back in 2007 as well.)

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Feeling Down? Lifting Weights Can Lift Your Mood, Too
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There’s plenty of research that suggests that exercise can be an effective treatment for depression. In some cases of depression, in fact—particularly less-severe ones—scientists have found that exercise can be as effective as antidepressants, which don’t work for everyone and can come with some annoying side effects. Previous studies have largely concentrated on aerobic exercise, like running, but new research shows that weight lifting can be a useful depression treatment, too.

The study in JAMA Psychiatry, led by sports scientists at the University of Limerick in Ireland, examined the results of 33 previous clinical trials that analyzed a total of 1877 participants. It found that resistance training—lifting weights, using resistance bands, doing push ups, and any other exercises targeted at strengthening muscles rather than increasing heart rate—significantly reduced symptoms of depression.

This held true regardless of how healthy people were overall, how much of the exercises they were assigned to do, or how much stronger they got as a result. While the effect wasn’t as strong in blinded trials—where the assessors don’t know who is in the control group and who isn’t, as is the case in higher-quality studies—it was still notable. According to first author Brett Gordon, these trials showed a medium effect, while others showed a large effect, but both were statistically significant.

The studies in the paper all looked at the effects of these training regimes on people with mild to moderate depression, and the results might not translate to people with severe depression. Unfortunately, many of the studies analyzed didn’t include information on whether or not the patients were taking antidepressants, so the researchers weren’t able to determine what role medications might play in this. However, Gordon tells Mental Floss in an email that “the available evidence supports that [resistance training] may be an effective alternative and/or adjuvant therapy for depressive symptoms that could be prescribed on its own and/or in conjunction with other depression treatments,” like therapy or medication.

There haven’t been a lot of studies yet comparing whether aerobic exercise or resistance training might be better at alleviating depressive symptoms, and future research might tackle that question. Even if one does turn out to be better than the other, though, it seems that just getting to the gym can make a big difference.

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Uncombable Hair Syndrome Is a Real—and Very Rare—Genetic Condition
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Everyone has bad hair days from time to time, but for roughly 100 people around the world, unmanageable hair is an actual medical condition.

Uncombable hair syndrome, also known as spun glass hair syndrome, is a rare condition caused by a genetic mutation that affects the formation and shape of hair shafts, BuzzFeed reports. People with the condition tend to have dry, unruly hair that can't be combed flat. It grows slower than normal and is typically silver, blond, or straw-colored. For some people, the symptoms disappear with age.

A diagram of a hair follicle
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Although there have been only about 100 documented cases worldwide, one of the world's leading researchers on the condition, Regina Betz, of Germany's University of Bonn, believes there could be thousands of others who have it but have not been diagnosed. Some have speculated that Einstein had the condition, but without a genetic test, it's impossible to know for sure.

An 18-month-old American girl named Taylor McGowan is one of the few people with this syndrome. Her parents sent blood samples to Betz to see if they were carriers of the gene mutation, and the results came back positive for variations of PADI3, one of three genes responsible for the syndrome. According to IFL Science, the condition is recessive, meaning that it "only presents when individuals receive mutant gene copies from both parents." Hence it's so uncommon.

Taylor's parents have embraced their daughter's unique 'do, creating a Facebook page called Baby Einstein 2.0 to share Taylor's story and educate others about the condition.

"It's what makes her look ever so special, just like Albert Einstein," Taylor's mom, Cara, says in a video uploaded to YouTube by SWNS TV. "We wanted to share her story with the world in hopes of spreading awareness."

[h/t BuzzFeed]

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