It appears the most of the matter in the Universe is non-luminous, IE not part of...

It appears the most of the matter in the Universe is non-luminous, IE not part of stars.

a) Describe the experimental evidence for the existence of this dark matter.

b) What is this dark matter made of, according to current thinking?

Solutions

Expert Solution

Part A:

How do we know Dark Matter exists?

First part in a series of four on Dark Matter

Some of you may have heard of dark matter, this mysterious type of matter that no one can see but makes 27% of the content of the Universe while visible matter (you, me, all stars and galaxies) accounts for only 5%. How do we know it really exists? In fact, its existence is confirmed in many different ways.

Galactic clusters

Fritz Zwicky, a Swiss astronomer, was the first to suspect the existence of dark matter in 1933. He was trying to measure the mass of a galactic cluster (a group of several galaxies) using two different methods. He tried to infer this mass from the speed of the galaxies. Just like kids on a merry-go-round have to hold on to avoid being ejected, galaxies are held together in a spinning galactic cluster by the gravitational force provided by the matter it contains. If there were not enough matter to create this force, the galaxies would simply scatter.

He then compared his result with the mass evaluated from the light the galaxies shed. He realised that there was way more matter in the cluster than what was visible. This matter of an unknown type generated a gravitational field without emitting light. Hence its name, dark matter.

Velocity curves of spinning galaxies

But it was not until the 1970

genius_generous answered 11 months ago

Next > < Previous

Related Solutions

Why is the luminous matter so much more compact than the dark matter?

24. How is dark matter believed to be similar to luminous matter, and how does it...

24. How is dark matter believed to be similar to luminous matter, and how does it differ? How do we know this? 25. Where in the Milky Way is our Solar System located? 26. What are the so-called peculiar motions of disk stars? 27. Describe the differences in age, color, metallicity, and location of Population I and Population II stars. Can you explain why we would expect the age, color, and metallicity of stars to be interrelated?

2) How does the clumping of dark matter differ from the clumping on luminous matter?

How density of ordinary matter varies throughout the Universe? How the density of "dark matter" varies...

How density of ordinary matter varies throughout the Universe? How the density of "dark matter" varies through the Universe? How the density of "dark energy" varies throughout the Universe?

Where in the Universe do we observe the ordinary matter? Select one: a. as galaxies and...

Where in the Universe do we observe the ordinary matter? Select one: a. as galaxies and intergalactic gas b. throughout the galaxies and in the extended halos around them c. throughout the observable universe

Dark Matter accounts for approximately 25% of the energy density of the Universe. The standard neutrinos...

Dark Matter accounts for approximately 25% of the energy density of the Universe. The standard neutrinos account for the majority of this with only a small amount explained by a population of MACHOs. True or false? Explain.

Explain how CMB data can be used to determine the dark matter content of the Universe.

1. How the existence of dark matter alters our ideas about the universe. Does it conform...

1. How the existence of dark matter alters our ideas about the universe. Does it conform to or deviate from known laws? How? 2. How does the existence of dark matter change our understanding of ourselves?

The Fundamental Forces govern interactions between all matter in the universe, yet we often don’t think...

The Fundamental Forces govern interactions between all matter in the universe, yet we often don’t think about them in detail. Select one of the four Fundamental Forces and read about it in detail from at least one internet source apart from Wikipedia. You may start there for an overview. Write a few paragraphs summarizing the force you chose, and include anything interesting about it or its discovery that you wish to share.

Assume ds2=−c2dt2+a2(t)dx2 and that a˙=κa for κ a positive constant. Our universe appears to be moving...

Assume ds2=−c2dt2+a2(t)dx2 and that a˙=κa for κ a positive constant. Our universe appears to be moving asymptotically toward such a case (although except with a 3-dimensional space instead of a 1-dimensional space). Determine what we call the "future horizon." If a light signal is sent out at time t1 from x1, in the positive x direction, what value of x2 will it get to, given an infinite amount of time? This difference, x2−x1 is called the future horizon.

Subjects