[DSRP Evidence](https://dsrpevidence.org/)

# Testing the problem of time with cold atoms

## Details

**Authors** Barontini, Giovanni

**Year** 2026

**Publisher** Physical Review Research

**Kind of work** article

**Discipline** Physics

**Applied** false

[Read it at the publisher](https://doi.org/10.1103/1h9j-df4k) 
10.1103/1h9j-df4k

## In authors' words

### What they set out to do (purpose)

Tests whether a closed quantum system can order its own events using only internal changes, without an external clock.

### Who or what was studied (sample)

One Bose-Einstein condensate of about 24,000 rubidium-87 atoms, run at several barrier heights.

### How they did it (methods)

A thin barrier divides the trap into an observed and an unobserved region. Entropic time is calculated from the entropy exchanged between them and compared with lab time.

### What they found (results)

Entropic time broadly reproduced the lab-time order of events across expansion and collapse, advanced with entropy exchange, and stopped when exchange stopped. A Schrödinger equation written in entropic time reproduced the measured evolution.

## Commentary

### In short

A sealed cloud of ultracold atoms built a working time variable from the entropy exchanged between two regions, with no external clock in the definition.

### Response

Time here is constructed from a distinction between two regions and the exchange between them. The result supports the DSRP resolution of temporal becoming: time needs no primitive of its own. The experiment is a laboratory analogue and does not establish how time arises in the universe.

**Patterns it shows** D, R

Shows the structure is there

## Questions it bears on

- Q19. [What is emergence (E)?](https://dsrpevidence.org/question/emergence)
- R1001. [Time Is Built from Distinction and Relationship](https://dsrpevidence.org/resolution/1001)

**Added** 2026-11-02

**How to cite this** Barontini, Giovanni (2026). Testing the problem of time with cold atoms. Physical Review Research.