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A gravity hill located near Leh in Ladakh, India.

What is the Secret Behind Gravity Hills?


Gravity hills are a type of slope where things seem to move against gravity on their own accord. For instance, if water is poured onto the surface of the hill, it would seem to move upwards, instead of in the opposite direction, as one might expect it to.

Gravity hills are also known as magnetic hills and mystery hills, and all three names say a little something about the attempt made to explain this strange phenomenon. Gravity hills occur in many parts of the world, with many being recorded in the United State. As these hills apparently defy the laws of nature, they have become tourist attractions.

What Happens on a Gravity Hill?

Gravity hills seem to defy the laws of physics. If an object, for example, a ball, is placed on a slope, it should naturally be pulled downwards by gravity. On gravity hills, the opposite appears to occur, i.e. the object moving upwards instead. Numerous explanations have been suggested to account for the existence of these hills. Sometimes, these are reflected in the names of such hills.

The name ‘gravity hill’, for instance, suggests that the gravitational pull of such hills is uneven, i.e. the force at its bottom is weaker than that higher up, therefore causing objects to move up its slope. It is true that gravity is not uniform everywhere on earth. For instance, areas closer to the earth’s equator experience a slightly weaker gravitational pull than those situated farther away from it.

Nevertheless, it has also been pointed out that “there are no known areas where it has been scientifically proven that gravity does not act the way it is supposed to act.” Thus, the explanation gravity hills are the result of a difference of gravitational pull between the top and the bottom of the slope is perhaps not quite feasible after all.

Poured water running "uphill", this photo is of a cultural heritage site in Canada.

Poured water running "uphill", this photo is of a cultural heritage site in Canada. ( CC BY-SA 3.0 )

Supernatural and Optical Illusion Explanations

Alternatively, some have turned to the supernatural in order to find an explanation for the occurrence of gravity hills. For example, there is a gravity hill in Lake Wales, Florida, where a local legend claims that there had once been a great battle between a giant alligator and a Native American chief. A lake was formed at the site by the ghost of either one of them, which is the cause of the gravity hill.

On other gravity hills, the supernatural are not directly involved in its formation, but are thrown into the mix nonetheless, perhaps to add flavor to the tale. For example, there is a gravity hill in Pennsylvania, “Just off Route 219 in Brandy Camp, Elk County”, which is supposedly haunted by the spirits of dead horses.

The sign at Spook Hill.

The sign at Spook Hill. ( CC BY 3.0 )

Another explanation, which is also perhaps the most plausible, attributes the existence of gravity hills to optical illusion. According to this explanation, the lay of the land and the surrounding landscape create an optical illusion, thus making us think that the downward slope of a hill is in fact one that goes upwards. Gravity hills continue to be a source of wonder, as the effects of the optical illusion can be quite convincing, even when one is aware of how they are formed.

Apart from gravity hills, this optical illusion has been utilized in a number tourist attractions known generally as ‘mystery spots’. In the United States, these attractions date back to the era of the Great Depression.

Mystery spots normally charge a small admission fee, and usually involve a building in which the laws of gravity seem to be broken. In order to attract more tourists, many of these sites have fanciful tales attached to them.

In Piercy, California, for example, there is an attraction known as Confusion Hill. The proprietors’ claim that a creature known as the Chipalope (half-chipmunk, half-antelope) originated there. According to this tale, there were a pair of chipmunks and a pair of antelopes walking in the woods, when they were suddenly transformed into a pair of chipalopes.

Confusion Hill, California.

Confusion Hill, California. ( Public Domain )

The male, who became known as ‘Chester the First’, gained self-awareness, and decided to hide from human beings, only appearing on Confusion Hill during the dead of night or in the early hours of the morning.

Featured image: A gravity hill located near Leh in Ladakh, India. The hill is alleged to have magnetic properties strong enough to pull cars uphill. Source: CC BY NC SA 2.0

By Wu Mingren

References

Arnold, J., 2015. 10 Magnetic Hills, Gravity Roads, and Mystery Spots. [Online]
Available at: http://mentalfloss.com/article/61636/10-magnetic-hills-gravity-roads-and-mystery-spots

Frizzell, M., 2005. Gravity Hills. [Online]
Available at: http://userpages.umbc.edu/~frizzell/gravhills.html

Gibbs, P., 1996. I know a place where things seem to roll uphill. How does it work?. [Online]
Available at: http://math.ucr.edu/home/baez/physics/General/roll-uphill.html

Wagner, S., 2015. Mystery Spots and Gravity Hills - What's the Explanation?. [Online]
Available at: http://paranormal.about.com/od/earthmysteries/ig/Mystery-Spots-and-Gravity-Hills/Mystery-Spots-and-Gravity-Hills---What-s-the-Explanation-.htm

Weird NJ inc, 2016. Gravity Roads. [Online]
Available at: http://www.weirdus.com/states/pennsylvania/roadside_oddities/gravity_hill/

Comments

Although the "secret" is not revealed, the answer seems to be it's all an optical illusion.
That's fine, so why all the mock spookiness over something that can be proved with a spirit level on a long piece of wood?

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