1- Chapter 12 - Special Relativity Flashcards
The Lorentz factor = (γ)
non relativlistic 1 way doppler shift.
1+ v/c for v<<<c>
</c>
relatgivlistic 1 way dopler shift
γ(1+v/c) or ( (1+v/c)/(1-v/c) )1/2
2 way relativlistic doppler shift
(1+v/c) / (1-v/c)
time dilation.
t=γτ(tau)
τ-frame of event
t-frame from observed
v/c = (in t1 and t2)
(t2-t1)/(t2+t1)
t2/t1=
(1+v/c) / (1-v/c)
λr/λe=
1+v/c
v/c= (in λ)
Δλ/λ for v<<
what is t1 (or Δtout)
the time interval between sending 2 pulses
what is t2 (or Δtback)
the time between reciving the 2 reflected pulses
What is a parsec
The distance to a star when the parralax angle it subtends is 1 second of an arc.
1o=60mins=3600 seconds of an arc.
What is radar ranging?
a way of measuring distance by sending a pulse to an object and measure the time taken.
(assuming its travellling at constant speed c)
Δλ/λ = (1 way and 2 way)
- v/c
- 2v/c
Hubbles law?
Plot speed of recession vs distance of a galaxy from earth.
v=H0r
Where H0 is the hubble constant and the reciprical of the age of the universe.
How brightness can be used to calculate distance
Assuming the brigneset star in one cluster is the same as another cluster you can work out the intensite difference , then use inverse sqaure law to find distance.
What is cosmalogical redshift?
λobserved/λemmited = Robserved/Remmited = 1 + Δλ/λ = 1+Z
R is distance
Caused by the expansion of the universe, which stretches the wavelengths of observeed light depending on the distance its travelled.
HOw can mass of a a thing be found?
the velocity of something orbiting it, and the orbit radius.
What did the universe used to be like
much smaller and hotter.
what is cosmic background raditation?
The largest red shifted light. IT was produced when the univesrse became cool enough for neutral atoms to form first relased as 1x10-6 m wavelength now 1x10-3m.
The temperature of the universe if also proportinal to this change in wavelength.
