Which of the following is the evidence that suggests the Universe is expanding? Explain
a
Objects in the Universe are getting smaller, meaning they must be travelling farther away from each other
b
The Universe is getting colder, which can only happen if the Universe is getting farther apart
c
The energy distribution in the Universe is thinner than before, meaning that energy is being spread out along farther distances
d
Almost all light in the Universe is red-shifted, meaning those objects creating that light are moving away from each other
d
Almost all light in the Universe is red-shifted, meaning those objects creating that light are moving away from each other.
This is the strongest evidence for the expansion of the Universe. The redshift of light occurs when objects are moving away from each other, causing the wavelength of light to stretch and move towards longer wavelengths. This phenomenon, called the redshift, has been observed in light coming from distant galaxies and other celestial objects. The consistent observation of redshift in the light from these objects strongly suggests that they are moving away from us and from each other, indicating the expansion of the Universe.