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The slope of gravity hills is an optical illusion,<ref>{{Cite web|url=http://pss.sagepub.com/content/14/5/441.short|publisher=Paola Bressan|website=SagePub.com|title=Antigravity Hills are Visual Illusions}}</ref> although sites are often accompanied by claims that [[magnetism|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.<ref>{{Cite web|url=http://www.sciencedaily.com/videos/2006/0609-the_mysterious_gravity_hill.htm |publisher=Science Daily |website=ScienceDaily.com |title=The Mysterious Gravity Hill:Physicists Show "Antigravity" Mystery Spots Are Optical Illusions |deadurl=bot: unknown |archiveurl=https://web.archive.org/web/20080217004146/http://www.sciencedaily.com/videos/2006/0609-the_mysterious_gravity_hill.htm |archivedate=2008-02-17 |df= }}</ref> |
The slope of gravity hills is an optical illusion,<ref>{{Cite web|url=http://pss.sagepub.com/content/14/5/441.short|publisher=Paola Bressan|website=SagePub.com|title=Antigravity Hills are Visual Illusions}}</ref> although sites are often accompanied by claims that [[magnetism|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.<ref>{{Cite web|url=http://www.sciencedaily.com/videos/2006/0609-the_mysterious_gravity_hill.htm |publisher=Science Daily |website=ScienceDaily.com |title=The Mysterious Gravity Hill:Physicists Show "Antigravity" Mystery Spots Are Optical Illusions |deadurl=bot: unknown |archiveurl=https://web.archive.org/web/20080217004146/http://www.sciencedaily.com/videos/2006/0609-the_mysterious_gravity_hill.htm |archivedate=2008-02-17 |df= }}</ref> |
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The illusion is similar to the [[Ames room]], in which objects can also appear to roll against gravity. |
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. |
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The opposite phenomenon—an uphill road that appears flat—is known in [[bicycle racing]] as a "[[glossary of bicycling#F|false flat]]".<ref>{{citation |url= https://books.google.com/books?id=PCO8d0hhzK4C&pg=PA114 |page= 114 |accessdate= July 20, 2013 |title= Cycling's Greatest Misadventures |editor1-first= Erich |editor1-last= Schweikher |editor2-first= Paul |editor2-last= Diamond |publisher= Casagrande Press LLC |year= 2007 |isbn= 978-0-9769516-2-9 }}</ref> |
The opposite phenomenon—an uphill road that appears flat—is known in [[bicycle racing]] as a "[[glossary of bicycling#F|false flat]]".<ref>{{citation |url= https://books.google.com/books?id=PCO8d0hhzK4C&pg=PA114 |page= 114 |accessdate= July 20, 2013 |title= Cycling's Greatest Misadventures |editor1-first= Erich |editor1-last= Schweikher |editor2-first= Paul |editor2-last= Diamond |publisher= Casagrande Press LLC |year= 2007 |isbn= 978-0-9769516-2-9 }}</ref> |
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==See also== |
==See also== |
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Revision as of 17:56, 12 May 2017
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
Wikimedia Commons has media related to Gravity hills.
- ^ 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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