Time seems to pass more slowly at the bottom of a mountain due to the time dilation effect caused by the more intense gravity at a lower altitude. This is a phenomenon predicted by Albert Einstein's general theory of relativity.
The human brain is not really a reliable clock: depending on our emotions or experiences, the perceived time changes completely. When we are bored or waiting impatiently, time seems to stretch endlessly. In contrast, during enjoyable or intense moments, it flies by without us noticing its passage. This is due to how our brain functions, as it does not have a true internal measure of time but reconstructs its length after the fact, based on memories, emotions, and perceived information. Research has also shown that age plays a role: the older we get, the more we tend to perceive time as passing quickly, due to habits, repeated experiences, and a decrease in new learning. In fact, this discrepancy between perceived time and actual time can simply be explained by the subjective nature of our brain, which constantly juggles memory, attention, and emotions to reconstruct our feeling of elapsed time.
Time is not an absolute and stable quantity everywhere: it changes depending on where you are, and especially according to the proximity of a source of intense gravity. The closer you get to a significant mass (like the Earth), the stronger the gravitational field becomes, and the more time "slows down" compared to a place where gravity is weaker. In other words, time near the Earth's surface passes slightly more slowly than at a higher altitude, such as the top of a mountain. This phenomenon, called gravitational time dilation, is so real that it must be taken into account in GPS positioning calculations, simply because satellites, placed far from the Earth, experience their time differently than we do.
According to Einstein, time and space are not two rigid entities that operate separately, but rather form a single block known as spacetime. This spacetime can be imagined as a kind of large elastic sheet: in the presence of a very massive object like a star or a planet, the sheet curves. It is this curvature created by mass and energy that becomes what we perceive as gravity.
As a result, the greater the mass, the more spacetime is curved, and the more time is affected. Specifically, this means that the closer you get to a significant mass (for example, when descending a mountain), the more time slows down compared to a place where gravity is weaker. This phenomenon, called gravitational time dilation, is at the very heart of Einstein's theory, and completely challenges our usual intuition that time passes at the same rate everywhere.
Several experiments have concretely demonstrated time dilation. By placing ultra-precise atomic clocks at the top and at the base of towers or mountains, scientists have observed a real shift: those located at the bottom run slightly more slowly than those at higher altitudes. The famous test conducted in 1971 with two airplanes flying around the Earth in opposite directions provided exactly this type of time shift predicted by Einstein's theory. These observations, repeated many times since with even more precise atomic clocks, completely confirm that gravity indeed influences the passage of time.
Time dilation, yes yes, that strange phenomenon arising from Einstein's theories, concretely impacts some of our technologies. A good example? The GPS systems in our smartphones and cars: without accounting for the slowing of time stronger near Earth, they would indicate an incorrect position after just a few hours. Satellites orbit at an altitude where gravity is weaker, so their time flows differently from ours on the ground. Their internal clock runs slightly faster than the one on Earth. If we didn't regularly correct this difference, our GPS maps would quickly be shifted by tens of kilometers. Another concrete example: in particle physics, elementary particles like muons, which are normally very short-lived, live longer when they zip through the Earth's atmosphere at high speeds. Without this time dilation, they wouldn't even reach the surface of the Earth. In short, it's not just a theoretical thing — time dilation is indeed part of our techno-scientific daily life.
The atomic clocks of GPS satellites account for the effects of gravitational time dilation. Without this correction, your GPS would accumulate errors of up to several kilometers per day!
According to Einstein's general relativity, time passes more slowly when one approaches a massive object like the Earth. Even a small difference in altitude affects the measurement of time on ultra-precise clocks.
In 2010, physicists measured a time difference between two atomic clocks placed just 33 cm apart in height – an astonishing proof that even a small change in altitude slightly alters the passage of time.
The film 'Interstellar' spectacularly showcases the effects of gravitational time dilation: one hour spent on the fictional planet near a black hole is equivalent to seven years on Earth.
Theoretically, if we only consider the aspects of time dilation, time passing slightly faster at higher altitudes would make living at the top of a mountain cause you to age just a tiny bit faster than living at sea level. However, the practical effects are negligible: they amount to only a few microseconds over an entire lifetime.
Using ultra-precise atomic clocks placed at different altitudes (for example, at the summit and at the base of a mountain), scientists have measured very small but predictable differences in the flow of time, thus confirming the gravitational time dilation predicted by Einstein.
A concrete and common example is the use of GPS satellites. Their system accurately accounts for the tiny time differences caused by general relativity to provide very precise information about your geographical location.
Sure! Here’s the translation: "Yes, our human perception of the passage of time is influenced by many factors such as age, emotions, psychological contexts, and the various stimuli to which we are exposed. However, these psychological factors have no direct relationship with the physical time dilation described in the theory of general relativity."
No, the time dilation observed on Earth is so slight that we cannot perceive it directly with our senses. Atomic clocks are needed to accurately measure these tiny time differences.
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