What is the evidence that galaxies contain dark matter?

Answer 1

all the normal matter (had to have had a template)

Answer 2

Dark matter was invented by astronomers to try to explain something that may not exist.
The outer arms of a galaxy are locked in step with the galactic center.
They theorize that without dark matter they would fly apart like a satellite system.
The solar system is a satellite system but a galaxy is not.
A galaxy is the end stage of an evolving universe,it is collapsing towards the galactic center.
The engine that drives the galactic center is the force that maintains the integrity of the outer arms without the intervention of dark matter.

Answer 3

while doing some analysis about the rotation of galaxies it was figured that there is a discrepancy between proposed rotation by newtons laws and observations.
the basic finding was that the outlying parts rotate faster than observed matter should have made them rotate.
the calculations showed that even with a high ammount of normal, but black matter the rotation couldn't be satisfyingly explained.
So scientists got a hint that there must be another mass being present causing this extra-kick.
The evidence just came from these observations and calculations so far.

the latest finding about the existence of dark matter came with observations of the galaxy cluster ZwCl0024+1652, about 5 billion lightyears away.
This Cluster contains mirror-images caused by gravitational lensing, which (for the first time) appear to being caused by the Dark Matter itself.
where dark matter is normally distributed roughly in the same place where normal matter unfolds its gravity inside galaxies, in this rare case it appears like the normal matter has been seperated from it by a collision with another galaxy.
So simulations showed a ringlike structure of dark matter forming a ring around the cluster with a size of about 2.6 million lightyears, obviously causing the gravitational lense.
since Dark matter itself does not reflect, absorbs or emits light it can be only found by gravitational effects it causes.

So this finding may underlines the existence of dark matter itself, which is still seen as to be too exotic for some scientists.

Answer 4

The orbital velocities of galaxies in bound galaxy clusters is too high if you only account for visible matter. There must be some "dark matter" in the middle that is binding the group together, otherwise it would fall apart. The best evidence for dark matter comes from the acoustic peaks in the CMB, there is no other explanation for the heights of the 2nd and 3rd peak. No real scientists doubt that dark matter exists in some form.

Answer 5

In galaxies stars farthest from the center should be moving slower than the ones closest to the center. The gravitational pull on them is less.
Astromomers noticed that object on the edges of a galaxy were moving much much faster than the speed they predicted. This means that some other force much be acting on them. This gave rise to the theory of dark matter.
The idea is that the dark matter also has a gravitational pull.

Answer 6

In order to determine how Galxies exist it is neccessary to know exactly what is dark matter . If dark matter is defined as the Substance of the Aether( a substance that Einstein Considered necessary for the transmisson of magnetism);then if would follow that All atomic masses are composed of this substance in their containment volumes.
Since Galaxies are also made of atoms the Same rules would apply.
Dark matter is called dark because it cannot be shadowed by light flux.This is what Michelson tried to do and it proved that it could not be done ;his experiment was null and moot.

Answer 7

The existence of "DARK MATTER" is inferred. That's what theories are for -- logical postulates based on observations and measurements that are still subject to confirmation and scrutiny.

The Milky Way galaxy spins too fast for the amount of "visible" matter present. Ergo, the existence of "dark matter" was inferred.

Answer 8

The main clue that scientists have to the existance of dark matter is to look at the gravitational interactions of stellar objects (e.g. galaxies). The only way the observed interactions can be explained would be from the added unobserved mass that dark matter would provide.