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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Hello, Can you please help me to answer next question abaut the case? Case: Mr. Hollon is a retired 76-year-old male who spent his entire working career as a fire fighter. He has a 22-year history of type 2 diabetes; he also has hypertension and emphysema. He is an active smoker (52-pack year smoking history), although he has attempted to stop smoking on several occasions. He wears a hearing aid in each ear because of hearing loss as a result of working around machinery for several years. Thinking in sensory perception: List three clinical manifestations that the cues suggest need to have further investigation or assessment. Thank you in advance!

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