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Doppler Effect Hubble parameter
Transcript of Doppler Effect Hubble parameter
As a source moves towards or away the frequency and wavelength shift, this is the Doppler effect.
For light it is a bit simpler than sound, there is no background medium to consider, so we only worry about motion towards or away.
Motion away from each other will cause the wavelengths to get larger, shifted to the red spectrum, we call this red shift.
We define the redshift parameter
together we can find v from z and z from v as shown here.
Hubble was the first to give physical evidence for the expanding universe.
With H =21 km/s /Mly
He used this idea of Doppler shifting, and found that there was a consistent relationships to the motion of all he observed. Specifically that the distance and velocity of these stars/galaxies were related
An interesting side note is this motion came from one starting point in time and could be solved backwards to find the 'age' of the universe.
A certain wavelength is measured from a known element to be 575.4 nm, but incoming from a distant galaxy it is measured to be 610.2 nm.
How fast is this galaxy receding from us?
How far away is it?