What is meant by vacuum? Where is the Vacuum?
Vacuum is a condition in which there is a space but there is no matter in it. According to the definition, this is the meaning, but there is no such vacuum detected till now without any matter even an atom. Artificially also a perfect vacuum is not created till now. There is some matter or the other between the planets, between the stars, in the galaxy and even in the ‘black hole’.
It is estimated that in a cubic centimeter of air above the sea level contains 30 billion billions of atoms (30 x 1018) are present. We know that humans are creating vacuum filled articles and are using it for various purposes. In this also at least there will be nearly 1 lakh of atoms. In the universe, not only the planetary matter present between the planets, there also lies star dust between them. So we can’t take it as perfect vacuum. But there is very less presence of matter between the gap of two stars or the two galaxies. It is estimated that there is an average of 1 atom or less matter present in every cubic meter in that place. So we can say that there is no perfect vacuum in the universe.