# Everpresent Lambda

@inproceedings{Ahmed2002EverpresentL, title={Everpresent Lambda}, author={Maqbool Ahmed and Scott Dodelson and Patrick B. Greene and Rafael Sorkin}, year={2002} }

A variety of observations indicate that the universe is dominated by dark energy with negative pressure, one possibility for which is a cosmological constant. If the dark energy is a cosmological constant, a fundamental question is: Why has it become relevant at so late an epoch, making today the only time in the history of the universe at which the cosmological constant is of order the ambient density. We explore an answer to this question drawing on ideas from unimodular gravity, which…

## 68 Citations

### Cosmological tests of Everpresent Λ

- PhysicsClassical and Quantum Gravity
- 2018

Everpresent Λ is a cosmological scenario in which the observed cosmological ‘constant’ Λ fluctuates between positive and negative values with a vanishing mean, and with a magnitude comparable to the…

### New solution of the cosmological constant problems.

- PhysicsPhysical review letters
- 2011

This work extends the usual gravitational action principle by promoting the bare cosmological constant (CC) to a field which can take many possible values and suggests a new view of time evolution.

### Why there is something so close to nothing: towards a fundamental theory of the cosmological constant

- Physics
- 2006

The cosmological constant problem is turned around to argue for a new foundational physics postulate underlying a consistent quantum theory of gravity and matter, such as string theory. This…

### On the thermodynamic and quantum fluctuations of the cosmological constant

- Physics
- 2004

We discuss, from a condensed-matter point of view, the recent idea that the Poisson fluctuations of the cosmological constant about zero could be a source of the observed dark energy [1, 2]. We argue…

### Cosmology of Quantum Gravities

- Physics
- 2017

A theory of everything explaining all the cosmological puzzles is an attractive utopia. It should explain how an expanding universe can arise from the chaotic foam of quantum geometry; whether the…

### The universe in a soap film

- Physics
- 2009

The value of the cosmological constant is one of the major puzzles of modern cosmology: it is tiny but nonzero. Sorkin predicted, from the Causet approach to quantum gravity, that the cosmological…

### Fine Structure of Dark Energy and New Physics

- Physics
- 2007

Following our recent work on the cosmological constant problem, in this letter we make a specific proposal regarding the fine structure (i.e., the spectrum) of dark energy. The proposal is motivated…

### Surface tension and the cosmological constant.

- PhysicsPhysical review letters
- 2006

A compelling analogy between the cosmological constant of the Universe and the surface tension of fluid membranes is presented and it is suggested that similar effects occur generically in quantum gravity models.

### Dynamics of dark energy

- Physics
- 2006

We review in detail a number of approaches that have been adopted to try and explain the remarkable observation of our accelerating universe. In particular we discuss the arguments for and recent…

### Brane-bulk energy exchange: a model with the present universe as a global attractor

- Physics
- 2006

The role of brane-bulk energy exchange and of an induced gravity term on a single braneworld of negative tension and vanishing effective cosmological constant is studied. It is shown that for the…

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