Gravity hill
A gravity hill, also known as a magnetic hill, mystery hill, mystery spot or gravity road, is a place where the layout of the surrounding land produces an optical illusion, making a slight downhill slope appear to be an uphill slope. Thus, a car left out of gear will appear to be rolling uphill against gravity.[1] There are hundreds of recognised gravity hills around the world.
The slope of gravity hills is an optical illusion,[2] although sites are often accompanied by claims that magnetic or supernatural forces are at work. The most important factor contributing to the illusion is a completely or mostly obstructed horizon. Without a horizon, it becomes difficult to judge the slope of a surface, as a reliable reference is missing. Objects one would normally assume to be more or less perpendicular to the ground (such as trees) may actually be leaning, offsetting the visual reference.[3]
The illusion is similar to the Ames room, in which objects can also appear to roll against gravity.Its basically a cabin built on the side of a mountain.
The opposite phenomenon—an uphill road that appears flat—is known in bicycle racing as a "false flat".[4]
See also
References
- ^ University of California Riverside article on phenomenon
- ^ "Antigravity Hills are Visual Illusions". SagePub.com. Paola Bressan.
- ^ "The Mysterious Gravity Hill:Physicists Show "Antigravity" Mystery Spots Are Optical Illusions". ScienceDaily.com. Science Daily. Archived from the original on 2008-02-17.
{{cite web}}: Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ Schweikher, Erich; Diamond, Paul, eds. (2007), Cycling's Greatest Misadventures, Casagrande Press LLC, p. 114, ISBN 978-0-9769516-2-9, retrieved July 20, 2013
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