Natural Science II Lab Exercise for Unit 64: Observing the Colors of Stars
Goal: to understand how changes in assumptions affect our model of the universe.
Materials and Equipment
Procedure

Read the "Background" link at the lab. Be sure you understand the three variables:

H_{0}, the Hubble constant or current rate of expansion of the universe. It is determined from the relationship v = H_{0}d, where v is the velocity at which a galaxy appears to be receding (based on Doppler Shift calculations), and d is the distance to the galaxy, based on Cepheid variable or other data. H_{0} is currently assumed to be about 73 km/s / Mpc (73 kilometers/second for every megaparsec distant the object is: the further the object is, the faster it appears to be moving).

Ω_{m} is the matter density parameter for the universe. It is a measure of how much mass there is in the volume of the universe.

Ω_{Λ} is the acceleration parameter. It is a measure of how much dark energy there is in the universe.

Begin with the values H_{0} = 73, Ω_{m} = .24, and Ω_{Λ} = .76. What do the curves for age, size, plot look back look like?

What happens if you increase and decrease H_{0}?

What happens if you increase and decrease Ω_{m}?

What happens if you increase and decrease Ω_{Λ}?
Report
Create a table with your values for each variable and a description of the resulting curves.
Hubble Constant H_{0}  Matter density Ω_{m}  Acceleration Ω_{Λ} 
73  0.24  0.76 
  
For what values are the curves "positive" (up from the lower left to the upper right)? For what values are the curves negative (from the upper left to the lower right)? Can you find three values for which the size curve is "flat" (horizontal)?
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