# Order-unity argument for structure-generated "extra" expansion

## TL;DR

This paper proposes that the observed acceleration of the universe can be explained by structure formation effects within classical general relativity, potentially eliminating the need for dark energy.

## Contribution

It introduces an order-unity argument showing structure-generated effects can account for cosmic acceleration without dark energy.

## Key findings

- Approximately 10-15% 'extra' expansion from structure formation.
- This effect can replace the need for 68% dark energy in cosmological models.
- The proposed explanation aligns with current observational data.

## Abstract

Self-consistent treatment of cosmological structure formation and expansion within the context of classical general relativity may lead to "extra" expansion above that expected in a structureless universe. We argue that in comparison to an early-epoch, extrapolated Einstein-de Sitter model, about 10-15% "extra" expansion is sufficient at the present to render superfluous the "dark energy" 68% contribution to the energy density budget, and that this is observationally realistic.