Help understanding the Friedmann equations?

[Misplaced]

Hello! I'm a senior at San Francisco State University, and I'm currently enrolled in a cosmology class. It's a GWAR class, meaning General Writing Assessment Requirement- I didn't expect much math. In fact, the first half of the class was basically an anthropology course, which is more in line with my interests. I was surprised when, come the second half of the coures, the 'paper' I was supposed to write was a long math explanation. I've taken three years worth of calculus plus a course on linear algebra and differential equations, so the math isn't what's difficult for me here. I believe my problem lies in understanding the concepts and variable in the equations. It seems there are a lot of different variables in the Friedmann equation that are a result of other equations, and some variables mean certain things about the universe, but getting any hard and fast information has been difficult. I'm coming to you all to see if you'll be able to provide to me an explanation of the use and composition of the Friedmann equation that I can understand. Here's the link to the paper I'm writing, so that you can see what I'm having questions about.

http://physics.sfsu.edu/~wcaudy/340paper2.pdf

Any other help regarding what the assignment is asking would be appreciated as well, though hopefully I'll be able to work all of that out myself once I have a better understanding of this equation and its meaning. Thank you very much for your help.

 

[Mordred]

Ok the problems they gave you aren't too complex, as this is an assignment I wouldn't want to give you too much information on how to solve the problems. Yes various parameters used in the Friedmann equations are calculated or involve other equations.. However there is a ton of info on each if you look at each parameter.

these two articles in this link, will only get you started. They were written as a FAQ level.

https://www.physicsforums.com/showpost.php?p=4687696&postcount=10

this one is a geometry article that applies in part to your questions.

https://www.physicsforums.com/showpost.php?p=4697773&postcount=30

" I'm currently enrolled in a cosmology class" what textbook did they provide you? it should cover the questions involved if its any form of cosmology text?

if you don't have a reliable textbook I would look into getting a copy of Barbera Ryden's "Introductory to cosmology" I can quarantee it will answer every question in this paper.

 

[Misplaced]

Thank you for the help. I'm definitely not coming here asking you to do the assignment for me. However, between doing some more research and the extremely helpful links you provided, I believe I have a solid understanding of the Friedmann equation's purpose and composition. Thank you again, I should be able to turn in a solid paper now. I'll make sure to recommend this site to others seeking help.

 

[Mordred]

Np glad the articles, helped fill in some gaps in a quick FAQ style slam course

 

[sardar]

Hello there! I can understand your struggle with understanding the Friedmann equations. They are indeed complex and can be quite daunting for someone who is not well-versed in mathematical equations. But don't worry, I will try my best to provide you with a simplified explanation of the equations and their significance in cosmology.

The Friedmann equations are a set of equations named after the Russian physicist Alexander Friedmann, who first derived them in the 1920s. These equations are used in cosmology to describe the evolution and dynamics of the universe. They are based on Einstein's theory of general relativity and relate the expansion rate of the universe to its energy density and curvature.

Now, let's break down the equations one by one. The first equation is called the Hubble parameter, denoted by H. It describes the rate at which the universe is expanding. It is directly proportional to the energy density of the universe and inversely proportional to the square root of the curvature of the universe.

The second equation is called the density parameter, denoted by Ω. This parameter represents the ratio of the actual energy density of the universe to the critical density, which is the density required for the universe to be flat. A value of Ω less than 1 indicates an open, negatively curved universe, while a value greater than 1 indicates a closed, positively curved universe.

The third equation is known as the acceleration equation, denoted by q. It describes the rate of change of the expansion rate of the universe. A positive value of q indicates that the universe is currently accelerating in its expansion, while a negative value indicates a decelerating expansion.

The fourth equation is called the deceleration parameter, denoted by q0. It represents the current value of the acceleration equation and is used to determine the age of the universe.

To sum it up, the Friedmann equations are used to understand the dynamics of the universe and its evolution over time. They take into account factors such as energy density, curvature, and expansion rate to give us a better understanding of our vast and ever-changing universe.

I hope this explanation has helped you in understanding the Friedmann equations better. If you have any further questions or need clarification on any specific aspects, do not hesitate to ask. Best of luck with your paper!