"Time is elastic": why time flows faster at the top of a mountain than at sea level

[Teacher]

Put one watch on the top of the mountain. Place another one on the beach. Eventually you will see that each clock shows a different time. Why? Time moves more slowly as it gets closer to Earth, because, as Einstein argued in his general theory of relativity, the gravity of massive objects like Earth distorts the space and time around them.

Scientists have observed for the first time the effect of "time dilation" on a cosmic scale, for example, when a star passes next to a black hole. Then, in 2010, researchers observed the same effect on a much smaller scale using a pair of extremely accurate atomic clocks, some of which were placed 33 centimeters taller than others. Again, time moved more slowly as the clock moved closer to Earth.

The differences were tiny, but the consequences were enormous: there is no absolute time. For every watch in the world and for each of us, time flows a little differently. But even if time flows in the Universe at a constantly changing speed, time still flows in some objective sense, doesn't it? Or maybe not.

Time is beyond physics. In his book The Order of Time, Italian theoretical physicist Carlo Rovelli suggests that our perception of time - our sense that time is forever advancing - can be a very subjective projection. Eventually, when you look at reality at its smallest scale (at least using the equations of quantum gravity), time disappears.

"If I'm watching the microscopic state of things - says Rovelli, - then the difference between past and future disappears ... in the elementary grammar of things there is no distinction between" cause "and" effect "."

So why do we perceive time as going forward? Rovelli notes that although time disappears on an extremely small scale, we still obviously perceive events that occur sequentially in reality. In other words, we observe entropy: order turns into disorder; the egg cracks and is beaten for scrambled eggs.

Rovelli says that key aspects of time are described by the second law of thermodynamics, which states that heat energy cannot move from less hot objects to hotter ones, so this process cannot be reversed. This is a one-way street. For example, an ice cube melts in a hot cup of tea, not the other way around. Rovelli suggests that such a phenomenon may explain why we are only able to perceive the past and not the future.

"Every time when the future is definitely different from the past, it has a kind of warmth, - says Rovelli in the Financial Times. " Thermodynamics traces the direction of time to what is called the 'low entropy of the past,' a still mysterious phenomenon that is raging debate. "

He continues:

“The growth of entropy orients time and allows for the existence of traces of the past, which provide the possibility of memories that hold our sense of identity. I suspect that something we call the "passage" of time needs to be understood by studying the structure of our brains, not through studying physics: evolution has turned our brains into a machine that feeds on memory to predict the future. This is what we perceive when we listen to the passage of time. Understanding the "flow" of time is something that may have more to do with neuroscience than with fundamental physics. Finding an explanation for the sensation of flow in physics can be a mistake. "

Scientists still have a lot to learn about how we perceive time and why time acts differently depending on the scope of the study. But there is no doubt that outside the realm of physics, our individual perception of time is also surprisingly elastic.

Strange subjectivity of time. Time at the top of the mountain moves differently than at the beach. But you don't have to travel any distance at all to experience strange distortions in your perception of time. For example, in moments of fear of death, the brain releases large amounts of adrenaline, which speeds up your internal clock, making you perceive the outside world more slowly.

Another common distortion occurs when we focus our attention in a certain way. Aaron Sackett, Associate Professor of Marketing at St Thomas University, told Gizmodo:

“If you think about how time flows at the present time, the biggest factor that influences your perception of time is attention. The more attention you pay to the passage of time, the slower it goes. When you are distracted from the passage of time - perhaps because of something happening nearby, or because of interesting dreams - you are more likely to lose track of time, feeling that it is slipping away faster than before. “Time flies when you're having fun, ” they say, but in reality it's more like “time flies when you think about other things.” This is why time also often flies by when you are definitely not having fun - for example, when you have a heated argument or are afraid of an upcoming presentation. "

One of the most mysterious ways in which people experience a distortion of time perception - is a technique of psychedelic drugs. In an interview with The Guardian, Rovelli described his feelings as follows:

“It was an extremely powerful experience, including on an intellectual level. Among the strange phenomena was the feeling of stopping time. Something was happening in my head, but the clock did not move forward; the passage of time no longer flowed. It was a complete violation of the structure of reality. "

It seems that few scientists or philosophers consider time to be entirely an illusion. In an interview with Physics Today, Rovelli noted:

“What we call time is a rich, multi-layered concept with many layers. Some temporary layers are only applicable on a limited scale in limited areas. This does not make them illusions."

An illusion is the idea that time flows with absolute speed. The river of time can flow forever forward, but it moves at different speeds between people and even within our minds.

Translator's comment. The article discusses different concepts of time considered in physics and psychology. The theory of relativity has changed our fundamental concepts in the understanding of time, denying its absolute (homogeneous) nature. The increase in entropy (a measure of disorder in closed systems) and the "big bang" theory (expansion of the universe from a hypothetical superdense point) determine the direction of time, which expresses the irreversibility of physical processes. This irreversibility is associated with one-pointedness, which is called the "arrow of time" - from