Quantcast
  • Register
PhysicsOverflow is a next-generation academic platform for physicists and astronomers, including a community peer review system and a postgraduate-level discussion forum analogous to MathOverflow.

Welcome to PhysicsOverflow! PhysicsOverflow is an open platform for community peer review and graduate-level Physics discussion.

Please help promote PhysicsOverflow ads elsewhere if you like it.

News

PO is now at the Physics Department of Bielefeld University!

New printer friendly PO pages!

Migration to Bielefeld University was successful!

Please vote for this year's PhysicsOverflow ads!

Please do help out in categorising submissions. Submit a paper to PhysicsOverflow!

... see more

Tools for paper authors

Submit paper
Claim Paper Authorship

Tools for SE users

Search User
Reclaim SE Account
Request Account Merger
Nativise imported posts
Claim post (deleted users)
Import SE post

Users whose questions have been imported from Physics Stack Exchange, Theoretical Physics Stack Exchange, or any other Stack Exchange site are kindly requested to reclaim their account and not to register as a new user.

Public \(\beta\) tools

Report a bug with a feature
Request a new functionality
404 page design
Send feedback

Attributions

(propose a free ad)

Site Statistics

205 submissions , 163 unreviewed
5,047 questions , 2,200 unanswered
5,345 answers , 22,709 comments
1,470 users with positive rep
816 active unimported users
More ...

  Does a positive cosmological constant increase or decrease gravity?

+ 1 like - 0 dislike
1723 views

In de Sitter space with a positive cosmological constant $\Lambda$, it is usually said that gravity is smaller than the value given by $1/r^2$, because $\Lambda$ *reduces* the attraction of masses at large distances.

However, many people (Verlinde, Milgrom, etc.) argue that a positive $\Lambda$ *increases* gravitational attraction at large distances. For example, MOND (with its new constant $a_0$) conjectures a higher gravitational attraction than $1/r^2$ (at large distances).

How can this apparent contrast be resolved?

asked Jun 22, 2020 in Astronomy by Christian (35 points) [ revision history ]
recategorized Jun 22, 2020 by Christian

Mond doesn't provide a valid illustration, a0 is not the gravitational constant.

Verlinde and Milgrom likely said that given some observational data and working on fitting, if you raise the cosmological constant, you would need to raise also the 'gravitational attraction'. Could you provide references to their exact claims?

 

1 Answer

+ 1 like - 0 dislike

MOND is not a replacement for dark energy but for dark matter, so of course that leads to a higher attraction. A cosmological constant has to do with dark energy and leads to an extra repulsive term so instead of ȑ=-GM/r² we have ȑ=-GM/r²+Λc²r/3

answered Jul 22, 2020 by Yukterez (10 points) [ revision history ]
edited Jul 23, 2020 by Yukterez

This is exactly what was written in the question. This is not an answer.

Your answer

Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
Please consult the FAQ for as to how to format your post.
This is the answer box; if you want to write a comment instead, please use the 'add comment' button.
Live preview (may slow down editor)   Preview
Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:
p$\varnothing$ysicsOverflow
Then drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds).
Please complete the anti-spam verification




user contributions licensed under cc by-sa 3.0 with attribution required

Your rights
...