Large-scale expansion of
universe :
•Slipher (Lowell) & Curtis (Lick) noted redshifts of “spiral nebulae”
•Hubble, Humason (Mt Wilson) correlated distance of galaxies with red Doppler shift – the more distant the galaxy the greater the redshift
® the more distant a galaxy, the more rapidly it is moving away from us
•linear correlation
between distance and
recession speed
•if 2 x more distant, recedes twice as fast
¯
Hubble Flow