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Dark Matter

• By
• John Kelly girls technology language college

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What is dark matter?

• That "something," cosmologists believe, is dark
  matter. In cosmology, dark matter refers to
  matter particles, of unknown composition, that do
  not emit or reflect enough electromagnetic
  radiation (light) to be detected directly, but
  whose presence may be inferred from gravitational
  effects on visible matter such as stars and
  galaxies. Dark matter takes up 90 of the
  universe.

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What does dark matter look like?
                                             
Dark matter Not dark matter

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Different types of dark matter

• Baryonic dark matter
• Non-baryonic dark matter is divided into three
  different types

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Baryonic dark matter

• Dark matter is matter that doesn't emit light
  composed of baryons, i.e. protons and Neutrinos
• Candidates for baryonic dark matter are
  non-luminous gas, Machos (massive compact halo
  objects), and brown dwarfs.

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Non Baryonic

• Non Baryonic which is divided into three
  different types
• Hot dark matter - nonbaryonic particles that move
  ultra-relativistically
• Warm dark matter - nonbaryonic particles that
  move relativistically
• Cold dark matter - nonbaryonic particles that
  move non-relativistically

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Hot dark matter

• Hot dark matter is a form of dark matter, which
  consists of particles that travel with
  relativistic velocities.
• The best candidate for hot dark matter is the
  neutrino. Neutrinos have very small mass, and do
  not partake in two of the four fundamental
  forces, the electromagnetic interaction, and
  strong interaction.
• They do interact with the weak nuclear force, and
  gravity, and are extremely difficult to detect.

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Cold dark matter

• Cold dark matter (or CDM) is a refinement of the
  big bang theory that contains the additional
  assumption that most of the matter in the
  Universe consists of material which cannot be
  observed by its electromagnetic radiation and
  hence is dark while at the same time the
  particles making up this matter are slowly moving
  and hence are cold.
• As of 2006, most cosmologists favour the cold
  dark matter theory as a description of how the
  universe went from a smooth initial state at
  early times (as shown by the cosmic microwave
  background radiation), to the lumpy distribution
  of galaxies and their clusters we see today the
  large-scale structure of the universe.

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A Type of dark matter
A black hole is a region of space time from which
nothing can escape, even light.
Who Discovered Black Holes?
                                               
Karl Schwarzschild is credited with being the
brilliant astronomer who developed the concept of
black holes. In 1916, using Einstein's general
theory of relativity, he began to make
calculations about the gravity fields of stars.
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What is going to happen ?
In the past scientists have said that dark matter
started from the big bang, but now astronomers
think that what happens to the universe in the
future will depend on how dense the universe is
and this is why dark matter is important. This
is because it has a gravitational effect on
ordinary matter.
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Extinction of dark matter

• Dark matter in the galaxy may have caused the
  worst mass extinction in 250 million years ago.
• Dark matter passing through Earth would have a
  direct biological effect and an indirect
  geological effect
• Earth has witnessed several mass extinctions of
  species over the past 600 million years

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Fun facts

• Did you know that time doesnt exist inside a
  black hole?
• Did you know nothing can escape a black hole not
  even light?