Question

12. A linear plot of the recession velocities of galaxies and clusters of galaxies (determined from redshifts) as a function of their distances from Earth results in a slope known as the “Hubble constant”, with units of 1/time, and its reciprocal (time) reveals that the Universe

a. is about 13.8 billion years old.

b. contains dark matter.

c. contains warped space.

d. has supernovae.

Answer 1

Answer:- a) is about 13.8 billion years old.

If we correctly understand how fast space expands, we can derive the distance between the two objects. That rate of expansion is called the Hubble Constant (H0). H0 = v/d where v is the radial velocity of the galaxy we're observing and d is the distance from Earth.If we determine the distance to that far away galaxy (d) and we know that the speed of light (c) is constant, then we know how long it took that light to reach us. The universe cannot be younger than that amount of time. So, based on our current understanding of the Hubble constant and the farthest away galaxies we've been able to observe, we know that the universe has to be at least 13.8 billion years old for us to be looking at those galaxies. Edwin Hubble observed the light emitted by the nearby galaxies. According to Doppler’s Effect, if a galaxy is moving away from us, the frequency of it’s light that would reach us will be smaller and hence it’s wavelength will be larger. This is known as red-shift. This observation wasn’t as startling as his next observation. He had hoped to find as many galaxies moving towards us as moving away from us. But, this wasn’t his observation. He discovered that all the galaxies in every direction were moving away from us and their acceleration were directly proportional to their distance from us, which means the farther they were the faster they were moving. The measure of rate of expansion is known as Hubble’s constant. This data is used to trace back to the origin of the universe. If the galaxies are moving away from each other at an exponential rate, then it implies that there must have been a time when all galaxies were summed up in a high density and high energy state also known as singularity The moment of spontaneous expansion of the universe from this state is known as Big Bang.