1. Leisure, leisure
2. Year
3. Time, for example, the current time is 12 o'clock.
Duration, for example, the duration of a class is 50 minutes.
5. Existence corresponding to space: Time is an attribute of the existence of the objective world.
Modern Chinese Dictionary explains that time is an objective form of material existence and a continuous system composed of past, present and future. This is a continuous manifestation of material movement and change.
It is an important factor in the connection between objects and the outside world.
The temporal property of an object can only exist when it is in contact with an external body. The time attribute between objects exists because of the synchronization between objects. Each object affects the time properties of the objects associated with it. They're synchronized.
Like a black hole, time stands still because it is isolated from the outside world. Although foreign objects enter it, they are all in sync with the black hole because of their strong gravity. Therefore, the time attribute of a black hole is only influenced by itself.
What time is it now? "or" how long is it before the new year? "I'm afraid even primary school students think this is a simple question. But if you turn the word order upside down and ask, "What is time? "I'm afraid most people will feel at a loss. That's true. " "Time" is the most important, common and commonly used concept for us: "We should seize time", "wasting time is wasting life" and "time is money" …
People regard time as an object that exists independently of anything else, and it passes endlessly and evenly; In middle school students' mathematics and physics textbooks, time is expressed as a straight line with a starting point, a unit, a direction, no beginning and no end. This is Newton's "absolute time" which accords with people's common sense, and it is also a scientific concept of time that was not generally accepted until the beginning of this century.
Truth is relative, and it always develops with the progress of science. After mankind entered the twentieth century, new achievements and discoveries in physics and astronomy challenged the basic concept of "absolute time". Albert Einstein's special theory of relativity points out that time cannot exist independently without observers of the universe and its events, and time is an aspect of the relationship between the universe and observers. Generally speaking, the measurement time of the same event is always different for different observers with relatively uniform motion. For example, a clock moving at a constant speed relative to the observer always goes slower than a clock stationary relative to the observer. The greater the relative speed of the clock, the closer it is to the speed of light, and the more obvious the effect. In addition, a direct corollary of Albert Einstein's general relativity is that clocks at different heights on the earth's surface have different speeds because of the gravitational field. The higher the altitude, the faster the clock speed, with a difference of about1.09×10-16 seconds/meter (altitude), that is, every time it rises 100 meter, the clock will be faster by one billion. These predictions made by Albert Einstein's theory of relativity have been verified by experiments. In addition, if we admit the "Big Bang" universe model put forward according to Albert Einstein's theory of relativity and the major astronomical discoveries of this century (red shift of spectral lines of galaxies outside the river, microwave background radiation, approximate helium abundance of different galaxies), we must accept that our universe must have a "beginning" (at least 65.438+000 billion years ago), and may even have an end (at least tens of billions of years later).
Fortunately, Albert Einstein's general theory of relativity and quantum mechanics have obtained the latest research results of modern cosmology: the universe we observed (the range is about 65.438+0.5 billion light years) is finite and unbounded, that is, it is finite in time and space scale but has no boundary (or edge), no beginning, no end, no birth and no death! Of course, this is only a relatively new model of the universe, and the scientific predictions made from it have to be verified by actual observations.
To sum up, "What is time?" The essence of the problem is to explore the essence of time, which is only a topic that few scientists and philosophers are keen to study, and it is far from a satisfactory result, so it seems that it will take a long time to explore. Fortunately, for the practical application of time, a conventional understanding is enough. In some fields, it is sometimes necessary to add relativistic correction to time.
Morning: from 0 to 6 o'clock.
Dawn: At dawn.
Dawn: It's almost dawn.
Morning: The period around sunrise.
Morning: The period from dawn to eight or nine o'clock.
Morning: The period from morning till noon 12.
Noon: during the day 12 o'clock.
Afternoon: from noon 12 to sunset.
Evening: The period from sunset to late at night.
Evening: Near evening.
Dusk: The period from sunset to sunrise.
Midnight: around 12 in the evening.
Night: The period from darkness to dawn.
The change process of all macroscopic material states is continuous and irreversible, which is their * * * same property. The measurement of this continuous event is called time.