Chapter 34, Problem 19TE

To determine

Whether it is dark matter of dark energy that keeps a galaxy from collapsing in on itself.

Answer to Problem 19TE

It is dark energy that keeps a galaxy from collapsing in on itself.

Explanation of Solution

Einstein in his study states that the gravity pushes the surroundings inward and thus causing the universe into a Big Crunch. But later it was assumed that there is some outward pull that keeps the universe from collapsing and thus, universe is static.

Later, the scientists in 1900’s collected the data from very distant galaxies, that 7.5 billion years ago the galaxies started expanding. They speculated that the galaxies are not expanding or receding on their own, but there is some energy that is causing in the increase in the rate of receding of galaxies. This energy is called dark energy.

Dark matter has no role in keeping the galaxy from collapsing it on itself.

Conclusion:

Therefore, it is dark energy that keeps a galaxy from collapsing in on itself.