Final answer:
The red shift of galaxies indicates they are moving away from us, with the level of red shift proportional to their speed. The fact that this shift increases with distance supports the theory of an expanding universe, stemming from the Big Bang approximately 14 billion years ago.
Step-by-step explanation:
The red shift observed in the light from distant galaxies indicates that these galaxies are moving away from our own galaxy. The degree of red shift is directly proportional to the galaxy's velocity relative to us, which means that the larger the red shift, the faster the galaxy is receding. This is due to an effect akin to the Doppler Effect, where the wavelength of light stretches as objects move away from the observer, shifting the light towards the red end of the spectrum. However, it's important to note that this motion is not simply due to the movement of the galaxies through space but to the expansion of space itself.
In particular, galaxies more than 50 million light years away exhibit a red shift in their light that is proportional to their distance from Earth. The fact that the red shift increases with distance implies that the universe is expanding, and this expansion causes all galaxies to move away from each other. The further the galaxies are, the faster they appear to recede, which is consistent with the predictions of the Big Bang theory, suggesting that the universe is approximately 14 billion years old.