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Date: 04 Mar 2006 08:08:02
From: Mourning Bull
Subject: science on seem's to roll up hill?
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[Physics FAQ] - [Copyright]
Updated May 1998 by PEG.
Original by Philip Gibbs 1996.
I know a place where things seem to roll uphill.=A0 How does it work?
Sometimes you may find or hear of a mysterious place where objects can
apparently roll uphill.=A0 This is a remarkably common illusion which is
found in numerous locations around the world.=A0 Usually it is a stretch
of road in a hilly area where the level horizon is obscured.=A0 Objects
such as trees and walls that normally provide visual clues to the true
vertical, may be leaning slightly.=A0 This creates an optical illusion
making a slight downhill look like an uphill slope.=A0 Objects may
appear to roll uphill.=A0 Sometimes rivers even seem to flow against
gravity.
Spots where the illusion is especially powerful often become tourist
attractions.=A0 Tour guides may like to claim that the effect is a
mystery or that it is due to magnetic or gravitational anomalies or even
that it is a paranormal phenomenon that science cannot explain.=A0 This
is not true of course.=A0 Natural anomalies can only be detected with
sensitive equipment and cannot account for these places but science can
easily explain them as optical illusions.
There are several things that enable us to sense which way is up.=A0 The
balance mechanism in our inner ears is one system we have, but visual
clues are also important and can be overriding.=A0 If the horizon cannot
be seen or is not level then we may be fooled by objects that we expect
to be vertical but which aren't really.=A0 False perspective may also
play a role.=A0 If a line of trees get larger or smaller with distance
away, our sense of perspective is thrown off.=A0 Objects far away may
seem smaller or larger than they really are.
People often overestimate the angle of a slope.=A0 If you are standing
on a slope of 1 degrees it will seem like a slope of 5 degrees and if
you stand on a slope of 5 degrees it may seem like you are on a slope of
30 degrees.=A0 Because of this effect the anti-gravity illusion can seem
stronger than it should be even when you know the cause.
Even when the true cause is understood it can be difficult to
believe.=A0 In some cases the sea horizon is partly visible and it seems
incredible that the effect can be an illusion.=A0 If you think there is
a magnetic anomaly just use two plumb lines, one made of iron and one of
stone.=A0 They would hang at different angles if a strong magnetic field
was acting horizontally.=A0 In fact magnetic anomalies are never that
strong and are never the cause as is easily shown.
However, it is not always easy to demonstrate that a slope that appears
to go uphill is really going downhill.=A0 Plumb lines and spirit levels
cannot be relied on if you think there is a gravitational anomaly.=A0 If
the slope runs parallel to a seaview it would be possible to compare a
plumb line with the horizon.=A0 Otherwise the only reliable way of
determining the true horizontal is by careful surveying.=A0 If a good
topographical map of the area is available it may be sufficient to show
which way the land is really sloping.=A0 The results will confirm the
illusion.=A0 Gravitational anomalies are always very small.=A0 In any
case, if there was a gravitational anomaly you should wonder how you
would notice it.=A0 There would be an equal effect on your sense of
balance as there is on any object.=A0 The anomaly would not be apparent
unless there was a clear view of the sea behind the slope, which there
never is.
A search on the web turned up a surprising number of examples of this
illusion.=A0 Most are natural while others have been constructed in
theme parks.=A0 Below is an incomplete list of the natural ones for
those who want to visit.=A0 Many thanks to those who have sent more site
details for this list.=A0 Do check locations are correct before making a
long journey and remember that it may be dangerous or illegal to stop or
reverse your car on slip roads and bends!
Mystery Spot Road, off Branciforte Dr.=A0 Santa Cruz, CA, USA. A spot
50m in diameter in the redwoods of the Santa Cruz Mountains
Mystery Spot, Putney Road, Benzie County, Michigan, USA.
Gravity Hill, Northwest Baltimore County, USA. along a public road that
ran through the Soldier's Delight environmental area.
Gravity Hill, Mooresville, Southwest Indianapolis, USA. Located off SR
42 on the South side of Mooresville.
Gravity Road, Ewing Road exit ramp off Route 208, Franklin Lakes, USA.
Mystery Hill, Blowing Rock, hwy 321, Carolina, USA.
Confusion Hill, Idelwild Park, Ligonier, Pennsylvania, USA.
Gravity Hill, off of State Route 96 just south of New Paris, Bedford
County, Pennsylvania, USA.
Gravity Hill (near White's Hill) , just South of Rennick Road, on County
Truck U, South of Shullsburg, in LaFayette County, Wisconsin, USA
Oregon Vortex, near Gold-Hill, Grants Pass, Oregon, USA.
Spook Hill, North Wales Drive, North Avenue, Lake Wales, Florida, USA.
Spook Hill, Gapland Road just outside Burkittsville, Gapland (Frederick
County), Maryland, USA.
Magnetic Hill, Near Neepawa in Manitoba, Canada.
Magnetic Hill, just off the Trans Canada highway, Moncton, New
Brunswick, Canada.
Gravity Hill, on McKee Rd. just before Ledgeview Golf Course in
Abbotsford, British Columbia, Canada.
Electric Brae, on the A719, Near Croy Bay, South of Ayr, Ayeshire,
Scotland.
Anti-Gravity Hill, Straws Lane Road, Wood-End, Near hanging rock,
Victoria, Australia
Morgan Lewis Hill, St Andrew, Barbados.
Hill South of Rome, in Colli Albani, near Frascati, Italy.
Malveira da Serra, on N247 coast road West of Lisbon, Portugal
Mount Penteli, on a road to Mount Penteli, Athens, Greece
Mount Halla, on the 1.100 highway a few miles south of the airport, near
Mount Halla, on the island of Cheju Do, South Korea
References:
"Skeptical Inquirer", Vol 16, No. 1, 1991; an article about the illusion
at Spook Hill.
"Seeing Is Believing?=A0 Haunted Shacks, Mystery Spots, and Other
Delightful Phenomena" by Chris Banta
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Date: 04 Mar 2006 07:19:52
From: ActionBill@gmail.com
Subject: Re: science on seem's to roll up hill?
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Mourning Bull wrote:
> [Physics FAQ] - [Copyright]
> Updated May 1998 by PEG.
> Original by Philip Gibbs 1996.
> I know a place where things seem to roll uphill. How does it work?
<snip >Snipped to conserve bandwidth.</snip>
Interesting post. I had heard about one of those places that were
mentioned in Pa.
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Date: 06 Mar 2006 00:41:16
From:
Subject: Re: science on seem's to roll up hill?
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half the population believes in astrology. we are desperate to believe
in mysteries. regardless, this topic should be reported to the CIA
because of its off topic content
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Date: 06 Mar 2006 07:50:21
From: Tom Wheeler
Subject: Re: science on seem's to roll up hill?
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CIA central intelegents...... W
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