Magnetic Hills: the roads where parked cars roll uphill, and the Italian lab that found out why
High in the mountains of Ladakh, in the far north of India, a road runs through a bare, dry valley. Beside it stands a yellow sign.
Drivers stop next to the sign. They put the car into neutral and take their feet off the brake.
Slowly, the car begins to move. And it seems to move uphill.
The passengers laugh and film it on their phones. Some are sure they felt a force pulling the car. The sign tells them that this place defies gravity.
This road is called Magnetic Hill. It is one of many Magnetic Hills around the world, also called gravity hills or spook hills. On all of them the same thing happens: a car, a ball or a stream of poured water seems to roll up a gentle slope. The mystery is simple to state. Is something on these roads really pulling things upward, or are our eyes being fooled?
The answer is known today. It took a spirit level, a surveyor's instrument and a psychology laboratory in Italy to find it. This is the story of how it was found.
The hill in the Himalaya
The Indian Magnetic Hill lies on the main road that crosses Ladakh, 26.5 km west of the town of Leh.
There are no trees here and no buildings to judge by. Bare mountains close in on every side.
Local tales grew around the place. The best known says the hill holds a magnetic force so strong that it drags cars up the slope. Travel websites repeat a further claim: that aircraft of the Indian Air Force once changed their route to avoid the pull of the hill.
No official source confirms the story about the aircraft. It appears only on travel sites, never with a date, a flight or a document.
The farmers of eastern Canada
On the other side of the world, in eastern Canada, a similar story began much earlier.
At the foot of a ridge on the north-western edge of the city of Moncton, in the province of New Brunswick, local farmers had noticed something odd since the 1800s. On one short dirt road, things seemed to roll the wrong way.
For decades it stayed a local curiosity. Then, in August 1933, an editor and 2 reporters from a provincial newspaper came to see it. Their article and photographs were the first wide report about the place.
Visitors started to arrive. A local woman who lived by the road saw an opportunity. With her husband she began selling homemade ice cream and pancakes from a small shack at the end of her driveway, and renting rooms in her house, which had been built in 1875. The place became known as Magnetic Hill.
After the Second World War, tourism grew fast. The gravel road, about 1 km long, became one of the main attractions of the region. Canada's official register of historic places now lists it as one of the 3 most visited natural attractions in the country.
What visitors do there has not changed. They stop at what looks like the bottom of a slope, put the car in neutral, and feel it roll backwards, up the hill they have just driven down.
The Electric Brae in Scotland
In Scotland, the same effect has its own name. On the west coast, on a country road south of the town of Ayr, lies a stretch known as the Electric Brae. "Brae" is a Scots word for the slope of a hill.
The name comes from an old belief that electric or magnetic attraction pulled the cars along.
To the eye, the road clearly slopes down toward a wooded glen. A car left there with the brakes off rolls slowly away from the glen, apparently up the hill.
Visitors kept stealing the metal road signs. So they were replaced with a stone set beside the road. The stone does not repeat the legend. It gives the measurements.
What the stone says
The stone says the stretch is about 400 metres long. It runs from a bend at about 87 metres above sea level to the edge of the glen at about 92 metres.
So the end that looks lower is in fact about 5 metres higher. The real gradient is 1 in 86: for every 86 metres you drive toward the glen, you climb 1 metre. That is a slope of just over 1%.
The cars are not rolling uphill. They are rolling downhill, exactly as gravity says they should. The road simply tilts the other way from what the eye reports.
**This is where the mystery ends: every time someone has put a spirit level on one of these roads, the real slope has run opposite to the slope that people see.**
A surveyor in the Italian mountains
Believers still had one answer left. Maybe, they said, gravity itself is tilted in these places. If gravity is bent, a spirit level would be bent too, and it would lie along with the eyes.
In the mountains of northern Italy there is a well-known spook hill of this kind. Researchers went there to close this last door. They did not measure on the strange stretch itself. They set up a theodolite, a professional surveyor's instrument, at a distance from it.
First they hung a weighted string inside the strange area and another one outside it, and checked that the 2 hung parallel. They did. Gravity pointed the same way in both places. Then they measured heights against marked poles.
The result: the road had a real slope of about 1%. And it ran opposite to the slope everyone saw.
The hill on a table
The last step came in 2003. A psychologist at the University of Padua, working with colleagues from the universities of Padua and Pavia in Italy, published a study in the journal Psychological Science. Its title said it plainly: antigravity hills are visual illusions.
The team built the hills indoors. Their models were wooden boards about 1 metre by 1.2 metres, joined by hinges and tilted by jacks. Volunteers looked at them through a small hole and said whether each stretch of "road" ran uphill, downhill or level.
They ran 4 experiments.
In the first, 20 volunteers looked at a slightly downhill stretch placed between 2 much steeper downhill stretches. 16 of the 20 saw the middle stretch as running uphill. The other 4 saw it as flat. Not one saw it as it really was. The researchers note that this setup copies a well-known gravity hill in the United States.
In another experiment they built a hillside out of green cloth, with 2 roads leaving from the same point, and a movable piece of cardboard that played the part of a distant horizon. A downhill road beside a steeper downhill road was seen as uphill by 7 of 8 observers.
The last experiment was about the Electric Brae. The team showed 24 new observers 3 versions of a photograph of the Scottish road, with the line of distant hills edited higher or lower. With a high horizon, the road looked downhill. With a low horizon, the same road looked uphill. Only the horizon had changed.
Why the eye gets it wrong
To judge whether a road goes up or down, the brain compares it with an imagined flat line at the height of our eyes. On open flat land, or facing the sea, that line is the real horizon, and we judge correctly.
On a gravity hill, the real horizon is hidden. Hills, ridges and the slope of the land take its place. The brain takes the wrong line as "level". A road that runs gently downhill, next to a much steeper downhill, then looks as if it climbs.
These roads also share a shape. The 2003 study notes that the strange stretch is usually short, 50 to 90 metres, only a few metres wide, and surrounded by natural hills with no buildings nearby. Buildings have upright walls, and upright walls would give the eye a true vertical to check against.
The same study lists more than 20 known hills in the United States, Canada, Europe, Australia, Barbados and South Korea. On every road that has been measured, the story is the same.
Conclusions and Open Questions
**A magnetic force pulls the cars.** This is the legend in Ladakh, and the origin of the name Electric Brae. The problem: plastic balls and water roll the same way, and neither reacts to a magnet. The measured slope explains the movement fully, with no extra force needed.
**Gravity itself is tilted in these places.** This was the last scientific-sounding defence of the mystery. The problem: at the Italian site, surveyors compared weighted strings inside and outside the strange stretch and measured from a distance. Gravity pointed the same way everywhere. The road simply sloped the other way.
**A curse.** At a gravity hill in Florida, visitors are told the effect is the curse of a Native American chief. The problem: it is a story, not evidence. The same effect was built on a table in a university laboratory.
**An optical illusion caused by a hidden true horizon.** The evidence: spirit levels and survey instruments on real roads, and 4 laboratory experiments that reproduced every known type of these hills. The problem: no serious one. This is the accepted explanation.
A few questions remain. The story of the Indian Air Force aircraft still circulates without a single source, and no one has shown that it ever happened. The 2003 study also found that the trick works far more easily in one direction: it was much easier to make a downhill look uphill than to make an uphill look downhill. The researchers note that this fits measurements published back in 1903, which found that people misjudge downhill slopes more than uphill ones.
And at every Magnetic Hill, one thing has not changed. The signs still promise a force that defies gravity. The cars still roll. And many visitors still drive away convinced, because their own eyes told them so.