Space has no physical properties. It is the play-field of the universe. Separation of objects does not mean the space is expanding. A New Yorker can take hydrogens, hydrogens, molecules, energy, and etc. in his body to Beijing. However, never the space of New York. Shipping countless containers from Shanghai to London can never take space from China to England. Space is in our hands and all around us. We have learned to manipulate matter and energy since our first existence on Earth, never space. Space is the absolute complement of the physical universe. It can not be disturbed, otherwise there would be no peace in the whole universe.

We see motion all around us, but never time. Counting clock ticks from sunrise to sunset is not time, but the reference of related motion of the Sun and the Earth. The paradox is, time does not exist in nature. It is not recyclable. Universe will continue without time.

Analogous to chemical experiments in submerged laboratory, all experiments are submerged in the particle sea. Radiations, particles, temperature, pressure, magnetic fields, passing neutrinos, and so forth. Universe is filled with knowns and unknowns that can not be isolated from our observations and experiments. A minute variation of clock on board of the International Space Station does not mean time has changed. Few parts per hundred, thousand, million, or billion may not be significant enough in an experiment. We can not look too hard for things we wish to find. It is not necessary the truth is not there. It could be what we choose to believe. We can always find the variations of clock readings with better technology, however, it stays independent of time and the progress of nature events.

Nevertheless, space and time can not go together. Space has existence, time has not. Space is absolutely recyclable, never time. And, space is fundamental, it is independent from mass, energy, and everything else. Haven't we confused by looking too hard.