# 100 years of the Cosmological Constant: what's next?

## TL;DR

This paper reviews the 100-year history of the cosmological constant, discusses current observational constraints on dark energy, and explores sociological factors influencing the field's consensus.

## Contribution

It provides a historical overview, summarizes recent observational results, and analyzes sociological influences on cosmological research and consensus formation.

## Key findings

- Current data are consistent with a cosmological constant ($w=-1$).
- Time variation of dark energy equation of state is not yet ruled out.
- Sociological factors may influence the consensus on the $
m extLambda$CDM model.

## Abstract

The Cosmological Constant $\Lambda$, in different incarnations, has been with us for 100 years. Many surveys of dark energy are underway, indicating so far that the data are consistent with a dark energy equation of state of $w=-1$, i.e. a $\Lambda$ term in Einstein's equation, although time variation of $w$ is not yet ruled out. The ball is now back in the theoreticians' court, to explain the physical meaning of $\Lambda$. We discuss sociological aspects of this field, in particular to what extent the agreement on the cold dark matter + $\Lambda$ concordance model is a result of the globalization of research and over-communication.