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Do You Use Only 10% of Your Brain?

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We may be biased, but we think the human brain is pretty special. All this week, mentalfloss.com is celebrating this miracle organ with a heap of brain[y] stories, lists, and videos. It all leads up to Brain Surgery Live With mental_floss, a two-hour television event hosted by Bryant Gumbel. The special airs Sunday, October 25 at 9 p.m. EST on the National Geographic Channel.

The simple answer is: No.

This myth is so prevalent that it is unquestioningly accepted as a pivotal plot point in movies, a motivational tactic for self-improvement, or justification for claims about ESP and other supposed untapped abilities of the human mind. A 2013 poll surveying over 2000 Americans found that 65 percent believed the 10 percent myth. A 2007 study in the British Medical Journal (BMJ) found that even some doctors weren't immune to the fallacy. But the truth is that everyone uses 100 percent of their brain.

Proving this idea wrong is relatively easy with modern technology. PET and fMRI scans show that even when we're sleeping, our entire brain is active on some level. Our observations of individual neurons or cells reveal no inactive areas of the brain. Metabolic studies of cellular metabolism in the brain show consistent activity as well. "Evidence from studies of brain damage, brain imaging, localization of function, microstructural analysis, and metabolic studies show that people use much more than 10 percent of their brains," according to the BMJ paper. "No area of the brain is completely silent or inactive."

But even before imaging techniques allowed scientists to definitively debunk this myth, how did it arise in the first place? And why has it held on into the era of such increased understanding of how the brain works?

Some attribute its origin to the prominent philosopher and psychologist William James, who in 1907 wrote in The Energies of Man, "We are making use of only a small part of our possible mental and physical resources." He probably meant that we all have untapped potential. Twenty-nine years later, in the introduction to Dale Carnegie's How To Win Friends and Influence People, Lowell Thomas wrote, presumably referencing that quote, "Professor William James of Harvard used to say that the average man develops only ten per cent of his latent mental ability."

From here, the sentiment seems to have spun off; versions of it found use in the science fiction and spiritual communities. It didn't help matters that in the 1920s and '30s, prominent psychologist Karl Lashley attempted to isolate regions of the brain by removing areas of the cerebral cortex in rats. When he found they were still able to learn and remember specific tasks, it contributed to the idea that there are large swatches of "inactive" brain mass. We know now the brain's plasticity allows it to recover from such injury and compensate for the loss. That's the very opposite of inactive. 

Decades later, the myth has persevered because of the attractive possibility it seems to present. It absolves us for not reaching our full potential, offers a persistent insecurity for self-help gurus to appeal to, and provides a pseudo-scientific explanation for the limits of human comprehension. 

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Big Questions
Where Is the Hottest Place on Earth?
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The summer of 2017 will go down as an endurance test of sorts for the people of Phoenix, Arizona. The National Weather Service issued an extreme heat warning, and planes were grounded as a result of temperatures exceeding 120 degrees. (Heat affects air density, which in turn affects a plane’s lift.)

Despite those dire measures, Phoenix is not the hottest place on Earth. And it’s not even close.

That dubious honor was bestowed on the Lut Desert in Iran in 2005, when land temperatures were recorded at a staggering 159.3 degrees Fahrenheit. The remote area was off the grid—literally—for many years until satellites began to measure temperatures in areas that were either not well trafficked on foot or not measured with the proper instruments. Lut also measured record temperatures in 2004, 2006, 2007, and 2009.

Before satellites registered Lut as a contender, one of the hottest areas on Earth was thought to be El Azizia, Libya, where a 1922 measurement of 136 degrees stood as a record for decades. (Winds blowing from the nearby Sahara Desert contributed to the oppressive heat.)

While the World Meteorological Organization (WMO) acknowledged this reading as the hottest on record for years, they later declared that instrumentation problems and other concerns led to new doubts about the accuracy.

Naturally, declaring the hottest place on Earth might be about more than just a single isolated reading. If it’s consistency we’re after, then the appropriately-named Death Valley in California, where temperatures are consistently 90 degrees or above for roughly half the year and at least 100 degrees for 140 days annually, has to be a contender. A blistering temperature of 134 degrees was recorded there in 1913.

Both Death Valley and Libya were measured using air temperature readings, while Lut was taken from a land reading, making all three pretty valid contenders. These are not urban areas, and paving the hottest place on Earth with sidewalks would be a very, very bad idea. Temperatures as low as 95 degrees can cause blacktop and pavement to reach skin-scorching temperatures of 141 degrees.

There are always additional factors to consider beyond a temperature number, however. In 2015, Bandar Mahshahr in Iran recorded temperatures of 115 degrees but a heat index—what it feels like outside when accounting for significant humidity—of an astounding 163 degrees. That thought might be one of the few things able to cool Phoenix residents off.

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

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Big Questions
How Does Autopilot Work on an Airplane?
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How does autopilot work on an airplane?

Joe Shelton:

David Micklewhyte’s answer is a good one. There are essentially a few types of features that different autopilots have. Some autopilots only have some of these features, while the more powerful autopilots do it all.

  • Heading Hold: There’s a small indicator that the pilot can set on the desired heading and the airplane will fly that heading. This feature doesn’t take the need for wind correction to desired routing into account; that’s left to the pilot.
  • Heading and Navigation: In addition to holding a heading, this version will take an electronic navigation input (e.g. GPS or VOR) and will follow (fly) that navigation reference. It’s sort of like an automated car in that it follows the navigator’s input and the pilot monitors.
  • Altitude Hold: Again, in addition to the above, a desired altitude can be set and the aircraft will fly at that altitude. Some autopilots have the capability for the pilot to select a desired altitude and a climb or descent rate and the aircraft will automatically climb or descend to that altitude and then hold the altitude.
  • Instrument Approaches: Autopilots with this capability will fly preprogrammed instrument approaches to the point where the pilot either takes control and lands or has the autopilot execute a missed approach.

The autopilot is a powerful computer that takes input from either the pilot or a navigation device and essentially does what it is told to do. GPS navigators, for example, can have a full flight plan entered from departure to destination, and the autopilot will follow the navigator’s guidance.

These are the majority of the controls on the autopilot installed in my airplane:

HDG Knob = Heading knob (Used to set the desired heading)

AP = Autopilot (Pressing this turns the autopilot on)

FD = Flight Director (A form of navigational display that the pilot uses)

HDG = Heading (Tells the autopilot to fly the heading set by the Heading Knob)

NAV = Tells the autopilot to follow the input from the selected navigator

APR = Tells the autopilot to fly the chosen approach

ALT = Tells the autopilot to manage the altitude, controlled by the following:

VS = Vertical Speed (Tells the autopilot to climb or descend at the chosen rate)

Nose UP / Nose DN = Sets the climb/descent rate in feet per minute

FLC = Flight Level Change (An easy manual way to set the autopilot)

ALT Knob = Used to enter the desired altitude

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

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