What is time? In the concept of different ways.

 What is time? 

The word "time" is commonly used to mean "a momentary time with the passage of time" or "the length between a certain time".

However, when asked "what is time?". This theme has its own perspectives in each field, such as psychology, biology, philosophy, natural science, physics, and cosmology. There are many definitions and ways of thinking, so it is difficult to explain in a general way.

Therefore, here, I would like to divide into the following five fields and divide the typical consideration of "what is time" into three parts and organize them as easily as possible.

・ Time flowing through the mind and body (body clock)

・ Changes in the view of time in religion and philosophy

・ "Absolute time" that progresses evenly anywhere in Newton

・ Einstein's expansion and contraction "relative time"

・ Relationship between space and time

Time flowing through the mind and body (body clock)

Why do you feel that time goes by faster as you get older?

As for the sense of time, it is often said that many adults feel that "when I was a kid, time was long, but when I became an adult, time passed quickly."

The reason for this is that, for example, when comparing the ages of 7 and 70, a year for a 7-year-old child is one-seventh of his life, while a year for a 70-year-old is only 70 minutes of his life. Since it is 1, the general theory is that this difference in ratio determines the psychological evaluation of                                                                               time.

In addition, as children experience new events every day, many memories remain vividly in the fresh brain, but adults only repeat the same experiences as in the past, so the hippocampus of the brain remembers each one. It is often said that one year has passed as soon as I noticed it.

Existence of body clock

For a long time, both humans and animals have lived in a daily cycle of waking up in the morning, working day and night, and the rhythm of life 24 hours a day is ingrained in the brain and body.

There is a function that acts as a clock in the body of an organism, and this clock is called a biological clock (biological clock). For example, it is said that even if you spend several days in a closed room without a clock, both humans and animals will wake up regularly in a cycle of about 24 hours. The reason is that every organism has the instinct of adapting to the environment and increasing the chances of survival in order to preserve the species.

How is the cycle of the body clock made?

So what is the body clock that sets the standard for creating cycles like the pendulum and balance of mechanical watches? The answer is the function of proteins, which are accumulated and decomposed inside cells every 24 hours a day. The mechanism by which the protein in the cell increases with activity in the morning and decreases at night, and the mass increases or decreases in this approximately 24-hour cycle, measures 24 hours as a biological clock. This mechanism allows the organism to produce a hormone-secreting rhythm that allows it to wake up and wake up at a fixed time in the morning and sleep naturally at night.

Recent bacterial studies have also shown that this protein repeats phosphorylation with phosphate groups attached and dephosphorylation with separation in a 24-hour cycle.

Animal biological time

It is said that the tempo of time varies from animal to animal. There is a close relationship between the size of an animal, the heartbeat, and the life span. Generally, the heavier and larger the animal, the longer it will live.

Larger animals have a slower heartbeat, for example, the heart of a mouse beats approximately once every 0.1 seconds, a human beats once a second, and an elephant beats approximately once every 3 seconds. The amount of energy consumed by the heart in one hit is the same for all animals, and it seems that the life of a mouse is short and the life of an elephant is long because it seems that the life of a mouse is short when the heart shoots about 1.5 billion times.

As a result, the heavier the animal, the slower the physiological time such as blood circulation, digestion / excretion, growth, and cell life, resulting in a longer life and a slower tempo. I can say that.

I don't know the reason, but according to one theory, the time in the body such as the cardiac cycle and lifespan is proportional to the 1 / 4th power of body weight. It's hard to tell if it's 1/4 power, but if your weight is 16 times (2 to the 4th power), the time will be doubled, and if you're 81 times (3 to the 4th power), it will be 3 times or 256 times. That means it will be quadrupled.

It's very interesting that each animal's evolutionary process, even in the same day, depends on their weight and size, the length of time they are designed for, and perhaps the length of the day they feel. is.

Changes in the view of time in religion and philosophy.

The concept of time in ancient religion

In the religions of many ancient civilizations such as ancient Egypt, Greece, and Maya, the world created by the gods has a circular structure that periodically repeats creation-survival-end-end-ruin ... and repeats infinitely. So it was thought that time could go back and repeat in the sense that it would follow the same path, or that it would last forever.

Also, in Indian philosophy such as Buddhism and Hinduism and Eastern thought, there was a similar idea that reincarnation is called reincarnation, and the soul that returned to the world after death is reborn many times.

Judaism also has a circular view of time, but in Christianity, the arrival, death, and resurrection of Jesus Christ by divine revelation are irreversible and irreversible. I am.

However, in an era when Christian missions before the 10th century were still limited, there were no tools to measure time other than sundials, water clocks, and burning clocks, and the general public was still conscious of time. It was thin. Time was the concept of being repeated on a yearly basis due to seasonal changes and annual harvests.

After the 11th and 12th centuries, Christianity began to influence the lives of ordinary people, denying the repeated notion of circular time, and time is God-dominated, moving toward the end. We live by changing to the concept of linear things.

Dogen Zen Master's Time Theory

Dogen, the founder of the Soto sect and a Zen priest who was active during the Kamakura period, is famous among the Japanese who preached about "what is time". In the volume "Uji" of "Shobogenzo" that he left behind, he states as follows.

"(Buddha) sometimes stands on a high mountaintop, and sometimes goes deep on the seabed ...

Pine and bamboo also have time, and I also have time ...

Existence is time, time is existence ...

If time runs out, mountains and the sea will run out ...

Having time means being alive ... (colloquial translation) "

In other words, Dogen's "Uji" means "Uji (space / existence)" and "time (time)", and time and space / time and existence are always one, and our life is , Always be "only now and here". I thought that stationary plants such as pine trees, like humans, make up time and space.

He explained that life is to live hard by becoming one with the Buddha while practicing at the moment of "only now and here".

"Revolution of time consciousness" away from religion

Mechanical clocks were invented in the West at the beginning of the 14th century, and in the 15th and 16th centuries, mechanical clocks were built not only in churches and monasteries, but also in city hall squares and markets around the world, and more accurate mechanical clocks became available. It will spread. Only then will the conversion from the indefinite time method to the fixed time method be made, and for the first time, citizens will become aware of their daily and hourly lives.

This is exactly the "revolution of time consciousness" from the time when God ruled to the objective time away from God, and by the clock tower of the square, the time is from the hands of God to the merchants who dominate the free city. In the hands, the merchants turned into tools that governed the region's economy, society, and politics.

Time thought by ancient Greek philosophers

The ancient Greek philosopher Plato seemed to think that the movement of the planet was advancing time like a clock-wound zebra, but his disciple Aristotle had nothing to do with the movement of the planet, but before and after the movement. We defined that time is determined by the number, the order before and after things happen.

It's still about the 4th-5th centuries BC.

After that, many philosophers regarded time as the most basic framework for human beings to exist and recognize something, along with space, and thought that everything would flow from the past to the present and the future. ..

Others think that time does not flow outside regardless of the mind, but is related to the work of the mind centered on the present, while including memories of the past and expectations for the future. I was there.

Time thought by philosophers after Newton

Newton's idea of   "absolute time and absolute space", which was active in the latter half of the 17th century, will be explained in detail later, but the simple idea is that "time always flows at the same speed anytime, anywhere". ..

Some philosophers disagree with it. The famous one is Immanuel Kant, who was active in the latter half of the 18th century, and he changes time and space not by absolute things but by human subjectivity, intuition, and sensibility, and various times and spaces. I thought that I could recognize the phenomenon that occurs in.