red-shift Flashcards
what is the doppler effect
if a wave source is moving relative to an observer there will be a change in the observed wavelength and frequency.
in the doppler effect, what can the wave source be
light, sound or microwaves
what happens when the wave source moves away from the observer (in the doppler effect)
the observed wavelength increases and the frequency decreases
what happens when the wave source moves towards the observer (in the doppler effect)
the observed wavelength decreases and the frequency increases
what is observed about the wavelength of light from most distant galaxies
there is an observed increase in the wavelength of light from most distant galaxies
what is red-shift
the further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength
what does the observed red shift of distant galaxies provide evidence for
the observed red shift provides evidence that the universe is expanding and supports the Big Bang theory (that the universe began from a very small initial point)
how does red shift provide evidence for the big bang
Astronomers have found that the further from us a star is the more its light is red shifted. This tells us that distant galaxies are moving away from us, and that the further a galaxy is the faster it is moving away. Since we cannot assume that we have a special place in the universe this is evidence for a generally expanding universe. It suggests that everything is moving away from everything else. The Big Bang theory says that this expansion started billions of years ago with an explosion.
what is cosmic microwave background radiation
CMBR is a form of electromagnetic radiation filling the universe. it comes from radiation that was present shortly after the beginning of the universe
why is CMBR evidence for the big band
the big bang theory is currently the only theory that can explain the existence of CMBR
