General Friedmann equation - how to solve this differential equation?

  • Thread starter Thread starter beertje
  • Start date Start date
Click For Summary
SUMMARY

The discussion centers on solving the Friedmann equation, a fundamental differential equation in cosmology that describes the expansion of the universe. The user seeks guidance on the correct approach to solve this equation, specifically regarding the square root operation and variable separation. The consensus emphasizes the importance of correctly identifying the sign when taking the square root and suggests separating variables as a key step in the solution process. This straightforward method is highlighted as a crucial technique for tackling the equation effectively.

PREREQUISITES
  • Understanding of differential equations, specifically the Friedmann equation.
  • Familiarity with the concepts of scale factor and cosmic time in cosmology.
  • Knowledge of variable separation techniques in solving differential equations.
  • Basic grasp of the Euler-Lagrange equation and its applications.
NEXT STEPS
  • Study the derivation and implications of the Friedmann equation in cosmology.
  • Learn about variable separation methods in differential equations.
  • Explore the significance of the scale factor in cosmological models.
  • Investigate the role of initial conditions in solving differential equations related to cosmology.
USEFUL FOR

Students of cosmology, physicists, and anyone interested in understanding the mathematical foundations of the universe's expansion.

beertje
Messages
3
Reaction score
2
Homework Statement
Solve the differential equation
Relevant Equations
(adot / a)^2 = k / a^q
friedman.png


Hello fellow physicists, I am taking a course "Introduction to Cosmology" and I am asked to solve this equation called the Friedmann equation. I understand what it represents (scale factor of cosmic time) but I have no idea how to solve this differential equation, even though I took a whole course on solving those (Euler-Lagrange etc.)

Please give me a small pointer :)
 
Physics news on Phys.org
Take the square root (which sign is the right one?) and then separate variables.
 
  • Like
Likes   Reactions: beertje
vanhees71 said:
Take the square root (which sign is the right one?) and then separate variables.
Thanks! That was way more obvious than I thought. Summer break always breaks me up.
 
  • Haha
  • Like
Likes   Reactions: PhDeezNutz and vanhees71

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
Replies
2
Views
2K
Replies
7
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
7
Views
3K
Replies
5
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K