You don’t notice it but time behaves differently on mountains, confirm scientists

We have all heard the old motivational adage that everyone has the same twenty-four hours in a day. It is a comforting thought meant to level the playing field, but it might not actually be true. That is because time is relative, and even the most precise clocks cannot exist in absolute time. But more importantly, it moves more slowly the closer you are to a heavy object and faster when you're away from it, like in the mountains. This was first proved by none other than Albert Einstein through his theory of general relativity, after which scientists observed this phenomenon many times, according to an IFL Science report published on 15 December 2025. 

Einstein's theory

In 1915, Einstein introduced the theory of general relativity, proposing that time is not absolute. He predicted that gravity warps the fabric of space and time, meaning that clocks ticking closer to a massive body like the center of the Earth experience stronger gravity and run slower than clocks farther away. Because gravity weakens as you move further away from the planet's center, altitude directly impacts the passage of time. To put it simply, an identical clock resting on a high mountain ridge will be a microscopic fraction of a second faster than a clock at sea level. 

Nonetheless, for decades, this gravitational time dilation was largely a theoretical concept because standard timekeepers were not sensitive enough to detect it at low altitudes. But that changed with the invention of optical atomic clocks, which use lasers and ultra-cold atoms to achieve unprecedented precision, losing less than a single second over tens of billions of years. Following this, a team led by Professor Scott Diddams at the University of Colorado Boulder launched an experiment to test this theory. 

The mountain experiment

To prove the theory, the researchers put one of these highly sensitive atomic clocks on the 4,348-meter summit of Mount Blue Sky while the other stayed closer to sea level. Then, using laser communication and fiber-optic cables, the team linked the high-altitude clock directly to the twin clock located at the university lab. They measure the microscopic differences in how the two instruments tick against one another. The team is actively quantifying the precise rate at which the altitude alters the flow of time.

Limitless possibilities

Once the scientists are done with this research, the possibilities of how it could be used further are endless. "If you put a clock on the side of a volcano, and it starts to run…more slowly than it used to, that might be an indication that magma is coming up," says Derek van Westrum, a physicist at NOAA. "In principle, it could be used to warn people that something might be happening." That said, it might be some time before this theory can be used that widely; still, it's really encouraging to see how much development is taking place in this regard.

A long way to go

While researchers continue to make strides, scientific facts are not as widely spread as one might think. According to a study conducted by a group of researchers, only 31% of the people they surveyed regarding time facts believed them. This means that, for the rest of the people, physical parameters like altitude or gravity can physically stretch a second that is absent from their day-to-day understanding. For most, their emotional state heavily warps how they perceive time's speed, with about 84.2% believing that time passes when they are enjoying an activity. 

Today years old

The study was further highlighted by a post from u/Choice-Scallion-3499 on Reddit about this theory, and people were left scratching their heads. u/givin_u_the_high_hat wrote, "It fascinates me that in some minuscule way this is happening from your feet to the top of your head." Meanwhile, u/dalaiis joked, "Til: my in-laws' house is almost directly next to the earth's core, because when I visit, time goes very, very slow."

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