• 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.


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


(propose a free ad)

Site Statistics

202 submissions , 160 unreviewed
4,981 questions , 2,140 unanswered
5,340 answers , 22,629 comments
1,470 users with positive rep
813 active unimported users
More ...

  Could the cosmological constant be due to vacuum fluctuations in a box, i.e., in a finite universe?

+ 0 like - 0 dislike

Assumption: If the universe were a finite box whose boundary is the cosmological horizon, then there would be a zero-point energy inside that box.

Consequence 1: This zero-point energy would be given by the size of the box. The calculated energy value is very similar to the measured cosmological constant. 

Consequence 2: The zero-point energy would have been larger when the universe was smaller. The cosmological constant would not be a constant, but decay in time. 

Question: Could that be the case?

asked Mar 3, 2019 in Theoretical Physics by Benny [ no revision ]
Most voted comments show all comments

Maybe, who knows? But note that actually "the box" has a lot of suff in it; in other words, the box state is not the ground state, but highly excited one. Finally, we cannot apply QM to the whole Universe, but only to a small part of it.

One issue would be the sign of the casimir force. As the casimir force turns out to be attractive, it can not be used to model a positive cosmological constant.

@Dilaton: Casimir force is a particular case of interaction of two neutral material bodies. Generally is it kind of Van des Waals force that can be a complicated function of the distance and orientation of two neutral bodies. The "borders of the Universe" are not such interacting  bodies.

The Universe itself is not that microscopic object to safely apply QM. On the contrary, it is a macroscopic object, or a macroscopic process, as a matter of fact. It is not "repeatable" and it is unknown to us, to tell the truth. Those who dare apply QM, QFT, string theory, etc. to the whole Universe pay Ein Taler.

@VladimirKalitvianski  I am afraid, your interpretation of the Casimir force is quite far from being complete. This force can arrise in any quantum system with boubdaries or interfaces (i.e. surfaces of volumes where quantum fields have different properties) Solid bodies are just one example of such boundaries. 

@IgnatRU: Then look into the "Quantum Electrodynamics" by LL (Berestetsky, Lifshitz, Pitaevsky), where they calculate the long-distance interactions of atoms. You will see the retarded interaction contribution. The inequality that defines well the distance $R$ is $R\gg a_0$ for example. It is clear that an ensemble of atoms interact in the same way: there are charges and electromagnetic field in the play. Some things can be simplified and reduced to effective "boundaries" with specific properties, but it is still a QED calculation.

Most recent comments show all comments

@VladimirKalitvianski  I am sorry, where did you get that QFT is only about a small part of the universe? 

@IgnatRU: I am sorry, but this is another subject. It is about Physics and its relationships with Mathematics. There was a prominent physicist, Julian Schwinger, who mastered math well and who knew QFT as one of its creators. He wrote a work called "Particles, Sources, and Fields" from a physical point of view. In this work he clearly oulined the domain of applicability of QFT. Maybe this answers your question.

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:
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).
To avoid this verification in future, please log in or register.

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

Your rights