By analyzing the light released or absorbed by the atoms of an object, we can measure whether the object is far away from the earth or close to the earth. when the object is far away from the earth, the frequency of these light will shift to the red end of the spectrum (low frequency), referred to as redshift, on the contrary, it is called blue shift. This unique light emitted by atoms is also affected by the mass of the elementary particles that make up the atoms, especially electrons. If the mass of an atom increases, the energy of the photons released by it will also become higher
the frequency of release and absorption will be blue-shifted. On the contrary, if the particles become lighter and lighter, the frequency will redshift. Astronomical observations have found that most galaxies have redshift, and the farther away the galaxies are from Earth, the greater the redshift. Based on this, many scientists believe that the universe must be expanding.
The number of stars that people can observe may be less than 1% of that of the real universe