Age of Universe @ 1 MeV, 1 GeV & 1014 GeV: Calculation

  • Thread starter Thread starter Ailar
  • Start date Start date
  • Tags Tags
    Temperature Time
Click For Summary
SUMMARY

The discussion centers on calculating the age of the universe at specific radiation temperatures: 1 MeV, 1 GeV, and 1014 GeV, within a Robertson-Walker universe framework. The present mass density is defined as ρm = 3Ω0H02/(8πG), with H0 = 100 h km s-1 Mpc-1 and a present radiation temperature of T0 = 2.725 K. The effective number of relativistic spin states, g*, is crucial for these calculations, with values of g* = 61.75 at 1 GeV and g* = 106.75 at 1014 GeV, assuming no supersymmetry. The discussion also highlights the importance of ignoring neutrinos for this specific problem.

PREREQUISITES
  • Understanding of Robertson-Walker metric in cosmology
  • Familiarity with the concept of effective number of relativistic degrees of freedom (g*)
  • Knowledge of cosmological parameters such as mass density (ρm) and Hubble constant (H0)
  • Basic principles of thermal radiation and temperature in cosmology
NEXT STEPS
  • Study the implications of the Robertson-Walker metric on cosmic evolution
  • Research the role of g* in cosmological models and its variations with temperature
  • Explore calculations of the universe's age at different energy scales
  • Investigate the effects of supersymmetry on g* and its impact on cosmological models
USEFUL FOR

Astronomers, cosmologists, and physics students interested in the early universe, radiation temperature effects, and the dynamics of cosmic expansion.

Ailar
Messages
2
Reaction score
0
Assume that we live in a Robertson-Walker universe with matter, radiation and curvature. The present mass density is ρm = 3Ω0H20/(8πG), where H0 = 100 h km s-1 Mpc-1 and Ω0(1+ρr,0/ρm;0) ≤ 1 (i.e., k ≤ 0). The present radiation temperature is T0 = 2.725 K.
Assume that only photons, with present temperature T0 = 2.725K contribute to the radiation; ignore neutrinos in this problem.
How old was the universe when the radiation temperature was 1 MeV? 1GeV?
1014 GeV? (Hint: you need g*, the effective number of relativistic spin states contributing to the energy density. At 1 GeV g* = 61.75 and at 1014 GeV, g* = 106.75 without supersymmetry or double this with SUSY.)
Thanks so much!
 
Physics news on Phys.org
This looks like a homework question, as such I am moving to the relevant homework forum. What attempts have you made the answer the question?
 

Similar threads

How Do You Solve H(T) at 1 MeV in Cosmology?
  • · Replies 1 ·
Replies
1
Views
2K
How Does the Cosmological Constant Change with the Expansion of the Universe?
  • · Replies 2 ·
Replies
2
Views
2K
Calculate the age of the Universe at a temperature
  • · Replies 6 ·
Replies
6
Views
2K
How Do Hydrogen and Helium Recombination Ratios Differ at z=1600?
  • · Replies 3 ·
Replies
3
Views
2K
High School What is the probability that the Universe is absolutely flat?
  • · Replies 96 ·
4
Replies
96
Views
12K
Graduate Determining Mass/Density of Universe: How Accurate?
  • · Replies 10 ·
Replies
10
Views
4K
Graduate My calculation of the density of the universe at (10^60)th of its present age
  • · Replies 2 ·
Replies
2
Views
4K
Graduate Modelling density as a function of time?
  • · Replies 17 ·
Replies
17
Views
8K
Graduate How Does Geometry Influence Our Understanding of the Universe?
  • · Replies 29 ·
Replies
29
Views
8K
Graduate Flatness Problem: Understanding Resolution in Big Bang Model
  • · Replies 5 ·
Replies
5
Views
3K