According to the Big Bang Theory, galaxies are _________________________________________________________________________________.
a
in constant motion
b
are moving away from each other
c
are moving at different speeds in different directions
d
are moving slower than in past times
b
are moving away from each other
According to the Big Bang Theory, galaxies are moving away from each other. This concept is known as the expansion of the universe. This means that the space between galaxies is continuously increasing, causing them to move apart. The farther apart two galaxies are, the faster they are moving away from each other. This phenomenon was first observed by astronomer Edwin Hubble in 1929 and has been confirmed through various observations and measurements since then. Therefore, option b, "are moving away from each other," is the correct answer.
According to the Big Bang Theory, galaxies are **moving away from each other**. This concept is known as the "expansion of the universe." This idea suggests that space itself is expanding, causing the galaxies to move apart.
To understand this concept, we can look at the observations made by astronomers. One of the most important pieces of evidence is the redshift of light from distant galaxies. When we observe light from these galaxies, we find that the wavelengths of the light are stretched, or shifted to longer wavelengths. This shift is called the redshift because it usually causes the light to appear more reddish.
The amount of redshift tells us how much the light has been stretched since it was emitted by the galaxy. By measuring the redshift, astronomers found that the light from almost all distant galaxies is shifted towards longer wavelengths. This redshift is an indication that those galaxies are moving away from us.
Furthermore, not only are distant galaxies moving away, but the farther away they are, the faster they are moving. This relationship between distance and speed of recession is known as Hubble's law, named after the astronomer Edwin Hubble. Hubble's law implies that the expansion of the universe is occurring uniformly in all directions.
So, according to the Big Bang Theory, galaxies are moving away from each other, and the speed of their motion is greater the farther away they are from us.