Time is based on seconds, minutes and hours. While the basis for these units has changed throughout history, their roots can be traced back to the ancient state of Sumer. The modern international time unit is determined by the electronic transition of the cesium atom. But what is this physical quantity?
Time measures the progress of events
Time is a measure of the progression of events. Physicists define this value as the progression of events from the past to the present and to the future. Basically, if the system is unchanged, it is outside this indicator. Time can be seen as the fourth dimension of reality used to describe events in three-dimensional space. It is not something that we can see, feel or taste, but we can measure its passage.
The arrow shows that time moves from the past to the future, and not vice versa
The hand on the watch shows that time moves from the past to the future, and not in the other direction. The physics equations work equally well whether the quantity goes forward into the future (positive time) or backward into the past (negative time). However, in the natural world, this value has one direction. The question of why it is irreversible is one of the biggest unresolved questions in science.
Promotional video:
One explanation is that the natural world follows the laws of thermodynamics. The second law of thermodynamics states that in a closed system its entropy remains constant or increases. If the universe is considered a closed system, its entropy (the degree of disorder) can never decrease. In other words, time cannot go back to the exact state in which it was at an earlier point. This value cannot move backward.
Deceleration or acceleration
Time is accurately counted by serviceable hours. In classical mechanics, it is the same everywhere. However, we know from Einstein's special and general theory of relativity that magnitude is a relative concept. The indicator depends on the observer's frame of reference. This can lead to subjective slowdowns when the time between events gets longer (expands) the closer one of them is to the speed of light.
Moving clocks run slower than stationary clocks, with the effect becoming more pronounced as the moving mechanism approaches the speed of light. Clocks in Earth's orbit record time more slowly than on its surface, muon particles decay more slowly when falling, and the Michelson-Morley experiment confirmed the contraction of length and expansion of magnitude.
Parallel reality helps to avoid the time paradox in time travel
The time paradox in time travel can be avoided by going into a parallel reality. Traveling means moving forward or backward at different moments, just as you can move between different points in space. Jumping forward in time occurs in nature. Astronauts on a space station are accelerated as they return to Earth and slow down in relation to the station.
Existing problems
However, time travel poses challenges. One of them is causation, or causation. Moving backward can provoke a temporary paradox.
The Grandpa Paradox is a classic example in science. According to him, if you go back and kill your grandfather before your mother or father is born, you can prevent your own birth.
Many physicists believe that time travel into the past is impossible, but there are solutions to the paradox such as travel between parallel universes or branch points.
Perception of physical magnitude
Aging affects the perception of time, although scientists disagree with this position. The human brain is able to keep track of time. The suprachiasmatic nuclei of the brain are the area responsible for natural daily or circadian rhythms. Neurostimulants and drugs significantly affect his perception. The chemicals that excite neurons make them function faster, while decreasing neuronal activity slows down the perception of time.
Basically, when you think everything is accelerating, the brain produces more events within a certain interval. In this respect, time really does seem to fly when you are having fun. But it seems to slow down during emergencies or danger.
Scientists at Baylor College of Medicine in Houston say the brain doesn't actually speed up, but an area like the amygdala is becoming more active. The amygdala is the part of the brain that is responsible for creating memories. As more memories are formed, time seems to drag on.
The same phenomenon explains why older people seem to perceive time at a faster pace than when they were younger. Psychologists believe that the brain forms more memories of new experiences than familiar ones. Since there are fewer new memories in the later period of life, time in the perception of an elderly person seems to pass faster.
The beginning and end of time
More and more scientists are inclined to believe that our Universe was born as a result of a powerful explosion of a certain conditional point, in which such indicators as mass, time and space were not noted.
Astronomer Stephen Hawking and his Cambridge colleague Neil Turok suggest that there was originally an idea from which the word was born. It was in these two concepts that time and space consisted.
It is unknown if the time has a start or an end. As for the universe, time has begun in it. The starting point was 13,799 billion years ago when the Big Bang occurred. This process is evidenced by the relic radiation in space and the position of the scattering galaxies. At this time, transitions from one level of natural organization to another begin to take place - from the nucleus to the atom, and then to the molecule, from which living matter appeared.
We can measure cosmic background radiation as microwaves from the Big Bang, but no earlier radiation has been noted.
One argument for the origin of time is that if it expanded infinitely, then the night sky would be filled with the light of old stars.
Will there be an end time?
The answer to this question is unknown. If the universe is expanding forever, time will go on. If another Big Bang occurs, our timeline will end and a new countdown will begin. In particle physics experiments, random particles arise from a vacuum, so it seems that the universe will not become static or timeless. Time will tell…
Maya Muzashvili