What is Time (En)

A question that, while it seems simple and self-evident, in reality, none of us can answer to this day. Time is known to everyone, but it is difficult to define and understand it. Science, philosophy, religion, and the arts have different definitions of time, but its system of measurement is relatively consistent. Clocks are based on seconds, minutes and hours, while calendars are based on days, months and years. However, the modern international unit of time is defined by the electronic transition of the cesium atom.

Physicists define time as the progression of events from the past to the present and the future. Basically, if a system is immutable, it is timeless or timeless. Time can be considered to be the fourth dimension of reality, used to describe events in three-dimensional space. It is not something we can see, touch or taste, but we can measure its passage.

The Arrow of Time.

The equations of physics work equally well whether time is moving forward into the future (positive time) or backward into the past (negative time). However, time in the physical world has one direction, called the arrow of time. The question of why time is irreversible is one of the greatest unsolved questions in science.

One explanation is that the physical world follows the laws of thermodynamics. The second law of thermodynamics states that in an isolated system, the entropy of the system remains constant or increases. If the universe is considered an isolated system, its entropy (degree of disorder) can never decrease. In other words, the universe cannot return to exactly the same state it was in at an earlier point. Time cannot move backwards.

Time dilation.

In classical mechanics, time is the same everywhere. Synchronized clocks remain in agreement. However, we know from Einstein's special and general relativity that time is relative. It depends on an observer's frame of reference. This can result in time dilation, where the time between events becomes longer (dilated) as one approaches the speed of light. Moving clocks run slower than stationary clocks, with the effect becoming more pronounced as the moving clock approaches the speed of light. Clocks on airplanes or in orbit record time more slowly than those on Earth, muon particles decay more slowly as they fall toward earth, and the Michelson-Morley experiment confirmed length contraction and time dilation.

Time travel.

Time travel means moving forward or backward to different points in time, just as you can move between different points in space. Jumping forward in time happens in nature. Astronauts on the International Space Station move further forward in time when they return to Earth due to its slower motion relative to the station.

The idea of traveling back in time, however, creates problems. One issue is causation or cause and effect. Moving back in time could cause a time paradox. The "grandfather paradox" is a classic example. Paradoxically, if you travel back in time and kill your grandfather before your mother or father was born, you could prevent your own birth so you couldn't travel back in time in the first place. Many physicists believe that time travel is impossible, but there are solutions to a time paradox, such as traveling between parallel universes or junction points.

Perception of time

The human brain is equipped to track time. The suprachiasmatic nuclei of the brain are the area responsible for daily or circadian rhythms. But neurotransmitters and drugs affect perceptions of time. Chemicals that excite neurons and fire faster than normal acceleration time, while reduced neuronal firing slows the perception of time. Basically, when time seems to speed up, the brain discerns more events within an interval. In this regard, time really does seem to fly when one is having fun.

Time seems to slow down in situations of emergency or danger. Scientists at Baylor College of Medicine in Houston say the brain doesn't actually speed up, but the amygdala becomes more active. The amygdala is the area of the brain that creates memories. As more memories are made, time seems to be running out.

The same phenomenon explains why older people seem to perceive time as moving faster than when they were younger. Psychologists believe that the brain forms more

The beginning and end of time.

As far as the universe is concerned, time had a beginning. The starting point was 13.8 billion years ago when the Big Bang happened. We can measure the cosmic background radiation as microwaves from the Big Bang, but there is no radiation of earlier origin. One argument for the origin of time is that if it stretched back infinitely, the night sky would be filled with light from older stars.

The answer to the question of whether time will ever end is unknown. If the universe was expanding forever, time would continue. If another Big Bang were to occur, our timeline would end and a new one would begin. In particle physics experiments, random particles arise from a vacuum, so it does not seem likely that the universe will become static or timeless. Only time will tell.

Basic points

• Time is the progression of events from the past to the future.

• Time only moves in one direction. It is possible to move forward in time, but not backward.

• Scientists believe that memory formation is the basis for human perception of time.

Does time actually exist

It is certain that the subjective experience of time that we experience as humans is just an illusion that can have no relation to the absolute "space" and "time" of Newton, nor to the unified "space-time" that he proposes Einstein's Theory of Relativity.

Some scientists and philosophers believe that time does not actually exist, rather it is a creation of our brains, in an effort to experience and explain the world around us. In this view, they are led by the thought that the past has passed, therefore has ceased to exist, the future is unknown and not yet existent, while the present is but an elusive fleeting moment. But there are also those who consider that time is part of reality, such as Albert Einstein, who supports the theory of the "Monolithic Universe, where the past, present and future are simultaneously present in the universe, as well as that time is the fourth integral dimension in the space-time continuum.

However, he stated that, "the distinction between present, past and future is a stubbornly and persistently recurring fantasy". This Monolithic Universe, however, is a Universe with rigid and fixed dimensions, without surprises, without surprises and without freedom, since our decisions as well as our evolution are supposed to be already inside a huge "box". Everything is predictable and given. Even futures, and can be revealed based on calculations, and the past is always present.

But at this point comes the conflict with quantum mechanics, which shows that the future is impossible to predict, since it is only subject to probabilities, while it seems that subatomic particles completely defy time. Furthermore, in all the equations of quantum mechanics, the parameter of time is absent, since they work equally well, either towards the future or towards the past.

Ultimately, the answer to the question, what is time, is not as simple as it first seems.

What has been mentioned above on this subject should not be taken as answers, but rather as motivation for further reflection and thought. Thank you for your time.