Time slows down in case of strong gravity due to time dilation predicted by Albert Einstein's theory of relativity. The more intense the gravity, the more curved the space-time is, resulting in a dilation of time, giving the impression that time is passing more slowly.
According to Einstein and his theory of general relativity, gravity is not simply a force. It actually corresponds to a deformation of space-time caused by the mass and energy of objects. Imagine a stretched sheet on which a heavy marble is placed at the center: it creates a bump, curving the surface of the fabric around it. The more massive the object, the greater this deformation. Planets therefore orbit around the Sun not because a mysterious force attracts them like a magnet, but because they naturally follow these curves traced in the geometric fabric of the universe. The more curved space-time is (near a star, a planet, or worse, a black hole), the more slowly time passes.
Time is not an absolute value but relative: it flows differently depending on the intensity of the gravitational field. The closer you are to a massive object like a planet or a star, the slower time passes. This phenomenon is called gravitational time dilation. Basically, the stronger the gravity, the slower the flow of time compared to a place where gravity is weaker. It may seem surprising, but it's very real! If we place two identical clocks, one on Earth and the other far out in space, after a while, they will no longer be synchronized: the one close to Earth will show a slightly lower time, because it has "experienced" time more slowly. This is not a matter of mechanics or clock manufacturing; it is truly time itself that slows down under the influence of gravity. Even more strikingly, near very compact objects like black holes, this slowing can be extreme, to the point that a distant observer would feel as if time is standing still at their horizon.
A famous test conducted in 1971, named the Hafele-Keating experiment, used ultra-precise atomic clocks placed in airplanes flying around the world. When they returned to Earth, surprise: they showed a delay compared to the clocks that stayed on the ground, clearly confirming that time slows down based on gravity and motion. Another even more concrete example: every day, GPS satellites have to adjust their internal clocks because up there, gravity is weaker, and time passes just a tiny bit faster than at the Earth's surface. Without this daily correction, your GPS navigator could quickly lead you to the wrong place! Nowadays, even experiments in laboratories on Earth easily demonstrate this phenomenon by measuring tiny time differences between two very slightly different altitudes.
The slowing of time due to gravity has many surprising effects in our daily lives. For example, GPS satellites must take this phenomenon into account. Why? Because their clocks run slightly faster than those on Earth, which is farther from our stronger gravity. If we did not account for this time discrepancy, GPS accuracy would completely go haywire after a few hours, and your car might end up next to a bakery instead of the restaurant you chose! Even astronauts who spend time in space return to Earth having aged just a tiny bit slower than those who stayed below. Well, okay, it's not enough to stay young forever, but it remains a real and measurable effect of time passing differently depending on the intensity of gravity.
Did you know that your head ages slightly faster than your feet? Indeed, due to Earth's gravity, time passes very slightly more slowly near the ground than at the level of your head, creating a tiny but measurable difference thanks to modern atomic clocks.
Did you know that in orbit around the Earth, astronauts age slightly more slowly than those of us who remain on the ground? On the International Space Station, astronauts gain about 0.007 seconds each year compared to us, due to gravitational time dilation and their high speed.
Did you know that without corrections made to GPS satellites, our navigation systems would accumulate an error of about 10 kilometers per day due to the effects of time dilation caused by their orbital speed and Earth's gravity?
Did you know that near a black hole, time can slow down to the point where just a few seconds for a nearby observer would translate to thousands or even millions of years for a distant observer?
From the perspective of a distant observer, an object falling into a black hole appears to slow down as it approaches the event horizon, eventually seeming to freeze. This is due to the extreme intensity of the gravitational field and the pronounced effects of gravitational time dilation. However, for the object itself, its proper time continues normally until it reaches the singularity.
Sure! Here’s the translation: "Yes, several experiments confirm this phenomenon. The most famous is the Hafele-Keating experiment conducted in 1971, which used atomic clocks mounted on airplanes. Today, GPS even daily adjusts satellite clocks to account for this gravitational time dilation!"
In reality, in orbit around the Earth, astronauts age very slightly faster than those who remain on the surface, because they experience a lower gravity (centripetal acceleration) aboard the International Space Station. However, this difference is so minuscule that it has no practical impact on their lives or aging.
Sure! Here’s the translation: “No, time dilation is never directly experienced. Each individual always continues to perceive the passage of time normally for themselves. However, when measuring and comparing two clocks placed in different gravitational fields, this phenomenon is clearly observed.”
In our daily lives on Earth, this slowdown of time due to gravity is infinitesimal and almost imperceptible. It only becomes significant in extreme situations, such as near a black hole or in the precise realm of GPS, which requires very high temporal accuracy.
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