what is space? what is time?
today, people's consensus is that our universe originated in a big bang, and the universe is expanding. the starting point of time is the starting point of the big bang.
so, what is space? before the big bang, did space exist? space also originated in the big bang. space is also opened by energy, and space also come from the singularitie.
einstein's space can be curved. then, using the term 'contours' in mapping, the 'contours' of space are called 'energy's contours'. space is formed by different intensity energy planes which superimposing curved surfaces paved by different intensity 'iso-energy level lines' . people's perception of the combination of projections on different 'iso-energy planes' at the same time is the space we know. just as a movie is actually composed of frames of images, people perceive the transformation of the images, and then they think that it is active.
the perception of time comes from the perception of space. the energy of space has been decaying, so time is considered irreversible. looking from a low-intensity energy space to a high-intensity energy space, you will feel like 'a day is above the sky, the world has been thousands of years'. for example, when closing to a high-intensity energy point like a black hole, time will feel stagnant, why? this is because low-intensity energy space does not confine energy as much as high-intensity energy space, and energy lost more in low-intensity energy space.
so, is time a real dimension? perceiving space requires a reference, and perceiving time also requires a reference. four-dimensional space-time plus an energy intensity dimension, time is the energy variety relative to the variety of a certain value in the energy intensity dimension, cause the variety is increasing or decreasing, and the variety in time is perceived. if the time's reference's variety is the same as variety at your location, then time has stagnated.
human itself is an energy body. compared with the earth, the energy of the human's body loses faster. what people perceive is the energy variety between the human's body and the earth, so people perceive the variety of time. and, the human's body belongs to the earth, so that the energy of the earth is almost unchanged while the human's body loses more and more energy.
people sometimes feel that time passes faster or slower. the feeling that time goes faster means that you think a long time has passed, but the real time has only passed for a while. this is because your body loses more energy than usual. such as when you are in sickness. on the inverse, the feeling of time goes slower, which means that you thought it was only a while, but the real time has passed for a long time. this is because your body loses less energy than usual. such as when you are in leisure time.
the time for everyone independent is different.
note: the fractal curve can cover the plane. for example, the hilbert curve.
note: according to the general theory of relativity, "the trajectory of inertial motion is the shortest path in space-time geometry (geodesis)". why does the object move along the geodesic line while without external force? this is like the spread of water or a volcanic eruption, the energy catharsis will first break through the weak point. and the dimension of time is the dimension of energy change (please look at the geographic mapping of contour lines to get a feel). so, "without external force" is actually "forced". the force received is related to the vector of energy release and the nature of the object's energy (positive or negative).