the expanding universe Flashcards
What does the doppler effect cause?
a shift in wavelengths of sound and light
How to work out the observed frequency?
fo=fs(v/v+-vs)
What happens to the light from objects moving away from us?
is shifted to longer wavelengths (redshift)
What is redshift?
the change in wavelength divided by the emitted wavelength
What is redshift in slowly moving galaxies?
the ratio of the velocity of the galaxy to the velocity of light z=v/c
How to work out the velocity of a distant galaxy?
v= The Hubble constant/ distance to the galaxy
What allows us to estimate the ages of the earth?
the Hubble-Lemaitre Law
What led us to the theory of the expanding universe?
measurements of the velocities of galaxies and their distance from us
How can the mass of a galaxy be estimated?
by the orbital speed of stars within it
Where did the evidence of dark matter come from?
the estimations of the mass of galaxies
Where did the evidence of dark energy come from?
the accelerating rate of expansion of the universe
What is the temperature of stellar objects related to?
the distribution of emitted radiation over a wide range of wavelengths
What happens to the peak wavelength of this distribution when the temperature of an object changes?
hot= shorter cool= longer
What happens to the radiation per unit surface when the temperature of an object changes?
hot=more
cold=less
What is evidence for the big bang theory?
- the expanding universe- a large number of galaxies showing redshift rather than blue
- cosmic microwave background radiation
- the darkness of the sky (oblers paradox)
- the abundance of the elements hydrogen and helium in the universe
