RP329 The Dark Mystery of Deep Space

 RP329 The Dark Mystery of Deep Space

Question: How many astronomers does it take to change a light bulb? Answer: None. Astronomers aren't afraid of the dark! Bad jokes aside, astronomers may not be afraid of the dark, but they certainly lose a lot of sleep over dark matter.
Dark matter is four times more common in our universe than ordinary matter, but it is impossible to see with a telescope, and scientists only know of its existence because of the effects it has on visible matter.
Actually, “know” is perhaps too strong a word. Dark matter is an idea, a hypothesis, which tries to fill in the gaps between what we can see and what scientific data tells us about the universe. However, experiments have yet to detect the existence of dark matter particles, and this has caused some scientists to doubt the standard model for the structure and formation of the universe.
The existence of dark matter was first suggested by a Swiss physicist named Fritz Zwicky in 1933. Observing a galaxy cluster called the Coma Cluster—where over 1,000 galaxies, each containing billions of stars, collect together in an unimaginably vast cosmic group— Zwicky found a puzzling inconsistency.
Zwicky made a mass calculation based on the amount of visible matter in the cluster and also calculated the speed at which the galaxies in the cluster were moving. He realized that this mass did not provide enough gravity to keep these fast-moving galaxies in orbit. The galaxies should have been flying out of the cluster, rather than staying inside it. Zwicky then calculated the mass of the cluster based on the speed of the galaxies and discovered that it was 400 times more than the calculation based on the visible matter. He reasoned that there must be some kind of invisible matter which made up the difference in the calculations.
Due to the extreme difficulties that scientists have in detecting dark matter, new theories about its formation and behavior are seldom conclusive. Scientists have to make assumptions based on the indirect influence of dark matter on other cosmic structures, and this means that the secrets of dark matter could, for a long time, remain in the dark.