4.3 Cosmology Flashcards
What are spectral black lines on a diagram
Absorbtion lines
Created when light from star is absorbed by elements in the outer layers.
What is redshift
Black lines are shifted towards the red end of the spectrum when we look at the most distant galaxies. Their wavelength is longer than it should be.
What can we deduce from redshift
That distant galaxies are moving away from us and that the universe is expanding.
The universe began as an extremely small initial point in the Big Bang.
Give an example of blueshift and what it means
Andromeda is moving towards us
What is hubbles law
Hubble saw that fainter galaxies showed greater redshift.
The recession velocity is proportional to the distance from us.
v=Hd
What are the units for the Hubble constant
Km/s/mpc (mpc = mega parsecs)
If we convert the km into mpc then we can express the units of the Hubble Constant as /s
The significance is 1/H gives the age of the universe in seconds
Who coined the phrase “The Big Bang”?
Fred Hoyle
1949
How old is the universe
14 billion years
What is cosmic microwave backround radiation
Microwave radiation that can be detected coming from the sky in every direction.
Perfectly matches the radiation emitted by a black body with a temperature of 2.7 k
Who discovered cosmic microwave background radiation and how
Arno Penzias and Robert Wilson
1965
By accident
Were trying to detect faint reflections from balloon satellites
Discovered “noise” all around sky from all parts of the sky at all times of day and night
Given Nobel prize in1968
Provides strong evidence for Big Bang theory
Name two probes built to study CMB
COBE NASA 1989 Confirmed CMB, Detected ripples in radiation WMAP NASA 2001 Wilkinson Anisotropy Probe Allows us to learn more about the structure of the early universe Estimate dark matter Confirm dark energy
What is dark matter
Matter which does not emit or reflect radiation but has detectable gravitational effects.
Makes up 95% of our universe
What could dark matter be made of
We don’t know, possibly: Black holes Neutrino’s WIMPs Weakly Interacting Massive Particles
Who first proposed the existence of dark matter and when?
Fritz Zwicky
1933
Give evidence for the existence of dark matter
Gravitational lensing
Light bent and distorted through huge amount of matter
Rotational curve for a spiral galaxy
Stars far away from nucleus traveling much faster than expected.
Only explicable if a great deal of invisible mass was present.
