a) Briefly explain the origin of the Cosmic Microwave Background and its importance for mod- ern cosmology. b) By considering a light ray traveling radially (so that de = do = 0), use the Friedmann- Robertson-Walker line element and the assumption that the value of the scale factor today is a(to) 1 to show that in a flat universe the present day physical cosmological horizon distance is given by = rto dt' RH = C a (t') c) Calculate the present day physical cosmological horizon distance for a flat, matter domi- nated FRW universe. Compare your result for the horizon distance with the distance cto and comment briefly on any difference. Justify the common approximation when calculating the cosmological horizon distance that the radiation dominated epoch may be neglected. = d) The last scattering surface is at redshift 21s 1100. Assuming a flat matter dominated FRW universe, calculate the proper distance to the last scattering surface.

Human Anatomy & Physiology (11th Edition)
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Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
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a) Briefly explain the origin of the Cosmic Microwave Background and its importance for mod-
ern cosmology.
b) By considering a light ray traveling radially (so that de = do = 0), use the Friedmann-
Robertson-Walker line element and the assumption that the value of the scale factor today
is a(to) 1 to show that in a flat universe the present day physical cosmological horizon
distance is given by
=
rto
dt'
RH
= C a (t')
c) Calculate the present day physical cosmological horizon distance for a flat, matter domi-
nated FRW universe. Compare your result for the horizon distance with the distance cto and
comment briefly on any difference. Justify the common approximation when calculating the
cosmological horizon distance that the radiation dominated epoch may be neglected.
=
d) The last scattering surface is at redshift 21s 1100. Assuming a flat matter dominated FRW
universe, calculate the proper distance to the last scattering surface.
Transcribed Image Text:a) Briefly explain the origin of the Cosmic Microwave Background and its importance for mod- ern cosmology. b) By considering a light ray traveling radially (so that de = do = 0), use the Friedmann- Robertson-Walker line element and the assumption that the value of the scale factor today is a(to) 1 to show that in a flat universe the present day physical cosmological horizon distance is given by = rto dt' RH = C a (t') c) Calculate the present day physical cosmological horizon distance for a flat, matter domi- nated FRW universe. Compare your result for the horizon distance with the distance cto and comment briefly on any difference. Justify the common approximation when calculating the cosmological horizon distance that the radiation dominated epoch may be neglected. = d) The last scattering surface is at redshift 21s 1100. Assuming a flat matter dominated FRW universe, calculate the proper distance to the last scattering surface.
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