Dark Universe: Dark Matter Dark Energy and the Fate of the Universe - PowerPoint PPT Presentation

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Dark Universe: Dark Matter Dark Energy and the Fate of the Universe

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Title: Dark Universe: Dark Matter Dark Energy and the Fate of the Universe


1
Dark Universe Dark Matter Dark Energy and the
Fate of the Universe
2
The Universe is huge, filled with many many
bright stars
3
There are something dark out there
Rotation curve A plot of orbital velocity versus
orbital radius The solar systems rotation curve
declines because the Sun has almost all the mass.
4
There are something dark out there
The rotation curve of the Milky Way stays flat
with distance. Mass must be more spread out
than in the solar system.
5
There are something dark out there
The visible portion of a galaxy lies deep in the
heart of a large halo of dark matter.
6
I am telling you, What we can see is nothing!
85 dark matter 13 hot gas 2 stars
7
What could be the Dark Matter? Two Basic Options
  • Ordinary Dark Matter (MACHOS)
  • Massive Compact Halo Objects
  • dead or failed stars in halos of galaxies
  • Extraordinary Dark Matter (WIMPS)
  • Weakly Interacting Massive Particles
  • mysterious neutrino-like particles

8
Search for MACHOs
MACHOs occasionally make other stars appear
brighter through lensing but there are not
enough lensing events to explain all the dark
matter.
9
Why do we believe in WIMPs?
  • Theres not enough ordinary matter.
  • WIMPs could be left over from Big Bang.
  • Models involving WIMPs explain how galaxy
    formation works.

10
WIMP Dark matter effects
11
The Fate of the Universe Dark Energy
Big Bang The birth of everything
12
Philosophers lose sleep on this question
  • Will the universe continue expanding forever?
  • Or, will it re-collapse (Big Crunch)?

13
Which one you like the most?
The fate of the universe depends on the amount of
dark matter.
14
This is how scientists do to find the answer
Insert TCP 6e Figure 20.14
The brightness of distant white dwarf supernovae
tells us how much the universe has expanded since
they exploded.
15
Big surprise !
In fact, the expansion appears to be speeding up!
Dark Energy
16
This is what in our Universe
17
Dark Universe Dark Matter, Dark Energy Enjoy in
the darkness!
18
And, South Dakota is the perfect place to
entertain ourselves in the darkness!
19
SDSMT is also part of it
20
Questions
21
Spiral galaxies all tend to have flat rotation
curves, indicating large amounts of dark matter.
22
Nova Standard candle for cosmology
23
The fact is
An accelerating universe best fits the supernova
data.
24
Summary-1 What do we mean by dark matter and
dark energy?
  • Dark matter is the name given to the unseen mass
    whose gravity governs the observed motions of
    stars and gas clouds.
  • Dark energy is the name given to whatever might
    be causing the expansion of the universe to
    accelerate.

25
Summary-2 Contents of Universe
  • Ordinary matter 4.4
  • Ordinary matter inside stars 0.6
  • Ordinary matter outside stars 3.8
  • Dark matter 23
  • Dark energy 73

Now you know this is indeed almost nothing!
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