Cosmology@Home

From BOINC Projects
Revision as of 20:20, 6 June 2026 by Al Piskun (talk | contribs) (update infobox)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search



Cosmology@Home
Project
StatusInactive
CategoryCosmology / Astrophysics
ComputeCPU
RequiresVirtualBox 4.3 or later (for camb_boinc2docker app); VT-x or AMD-v
Development
DeveloperMarius Millea, Benjamin D. Wandelt
AuthorMarius Millea, Benjamin D. Wandelt
SponsorUniversity of Illinois at Urbana-Champaign; Institut Lagrange de Paris; Institut d'Astrophysique de Paris; NASA; Planck project
Initial releaseJune 26, 2007  (19 years ago)
DiscontinuedJanuary 10, 2024  (2 years ago)
Software
Written inC, C++ (CAMB); Python (server tooling)
Operating systemWindows XP or later, macOS 10.8 or later, Linux (64-bit)
BOINC statistics
Stats as ofJune 30, 2017  (9 years ago)
Performance17494.51 GigaFLOPS
Active users5,086
Total users70,212
Active hosts11,612
Total hosts170,377
Metadata
Websitehttps://www.cosmologyathome.org/

Cosmology@Home is a volunteer computing project that runs on the Berkeley Open Infrastructure for Network Computing (BOINC) platform. Its central goal is to compare theoretical models of the universe with observational data, and to identify the range of cosmological parameters that best fits measurements from instruments such as the Wilkinson Microwave Anisotropy Probe (WMAP), the Hubble Space Telescope, and the Planck satellite.[1]

The project was originally hosted at the Departments of Astronomy and Physics at the University of Illinois at Urbana-Champaign (UIUC). In December 2016 it was transferred to the Institut Lagrange de Paris and the Institut d'Astrophysique de Paris, both located at what was then known as Pierre and Marie Curie University in France.[2][3]

Temperature map of the cosmic microwave background (CMB) as measured by the Planck satellite. Cosmology@Home used volunteer computers to generate theoretical CMB power spectra used in training the PICO algorithm, which in turn was applied to precisely this kind of data.

Background and motivation

The discipline of physical cosmology seeks to determine the values of the fundamental parameters that govern the large-scale structure and evolution of the universe. These include quantities such as the Hubble constant H0, the total matter density Ωm, the baryon density Ωbh2, the dark matter density ΩCDMh2, the spectral index of primordial density fluctuations ns, and the amplitude of those fluctuations As. Together these parameters define what is known as the standard Lambda cold dark matter (LCDM) model of cosmology.

A central observational probe for constraining these parameters is the cosmic microwave background (CMB), the relic thermal radiation left over from roughly 380,000 years after the Big Bang. The tiny temperature anisotropies across the CMB sky, characterised by the angular power spectrum Cℓ, encode information about the physical conditions of the early universe and the values of these parameters.[4] Computing the predicted power spectrum for a given set of parameters requires running sophisticated Boltzmann codes such as CAMB (Code for Anisotropies in the Microwave Background), which can take many hours per model evaluation. To explore a realistic parameter space involving hundreds of thousands of candidate models, this demands an enormous amount of computational power - the exact problem Cosmology@Home was designed to solve.

History

Cosmology@Home was created by Marius Millea, then a graduate student astrophysicist at UIUC, along with professor Benjamin D. Wandelt.[5] The project launched for closed alpha testing on 30 June 2007, opened public alpha registration on 23 August 2007, and entered beta testing on 5 November 2007.[6]

Early work units were straightforward CAMB runs on Windows and Linux. Over time Millea introduced a Dockerised application named camb_boinc2docker - leveraging VirtualBox-based virtualisation via the BOINC vboxwrapper - which allowed the science application to be shipped as a portable Docker container, greatly simplifying deployment and eliminating the need to compile separate native binaries for each supported platform.[7] This innovation also gave birth to the open-source tool boinc-server-docker, which was originally developed for Cosmology@Home and has since been adopted as a general framework for hosting BOINC projects using Docker containers.[8]

In August 2017 a domain registration lapse following the server migration from UIUC to Paris caused the cosmologyathome.org domain to expire briefly; Millea posted updates on the BOINC forums under the temporary URL cosmos.iap.fr while the domain was recovered.[9]

By the early 2020s the project entered a prolonged period of low activity. SSL certificate renewals lapsed repeatedly between 2022 and 2024, preventing users from logging in or downloading new work units.[10] The project was eventually removed from the official BOINC active project list after the project administrator could not be reached.[11] BOINCstats retired the project from tracking in October 2024.[12]

Science

Goal

The core scientific goal of Cosmology@Home is to find the set of cosmological parameters that best describes the observable universe, by comparing theoretical predictions with actual measurements. The project specifically targets the comparison of theoretical models against:

  • Fluctuations in the CMB as measured by WMAP and the Planck spacecraft
  • The universe's expansion rate as measured by the Hubble Space Telescope
  • Large-scale structure data from galaxy surveys

Results from the project can also help scientists design future observational experiments and prepare analysis pipelines for upcoming telescopes and satellites.[1]

Method: sampling parameter space with CAMB

For any given class of cosmological models, Cosmology@Home generates tens of thousands of sample "universes", each defined by a unique combination of cosmological parameters. Each sample is sent to a volunteer's computer as a work unit. The volunteer's machine runs the CAMB code to compute the CMB power spectrum for that parameter combination - a calculation that can take several hours on a standard processor. The result, a tabulated list of angular power spectrum values Cℓ as a function of multipole order ℓ, is returned to the project server.[7]

PICO: machine learning from volunteer results

Once a sufficiently large training set of spectra has been collected from volunteers, the project uses a machine learning algorithm called PICO (Parameters for the Impatient Cosmologist), which was developed specifically by Fendt and Wandelt at UIUC for this purpose.[13] PICO learns to emulate the full CAMB computation by fitting multivariate polynomial functions to the training set. Once trained on approximately 20,000 examples (a process that takes about 30 minutes), PICO can replicate CAMB's output for any similar universe in just a few milliseconds per evaluation, rather than the hours required by CAMB itself.[7]

This emulation approach allows cosmologists to run a full Markov Chain Monte Carlo (MCMC) parameter estimation - involving hundreds of thousands of model evaluations - in a few hours on a single CPU, rather than the months that would be required using CAMB directly for each step.

All-sky map of the CMB from WMAP's seven-year data release. Measurements from WMAP were a primary observational dataset used in training and validating the PICO algorithm developed through Cosmology@Home.

A second, higher-accuracy paper extended the PICO algorithm to more general cosmological models and described the training methodology in detail, specifically demonstrating that PICO can be trained using the geographically distributed pool of hosts contributing to Cosmology@Home.[14]

PICO was subsequently adopted widely by the broader cosmology community. It was notably used in the analysis of data from the Planck satellite's CMB power spectra likelihood tests,[15] and in the analysis of South Pole Telescope CMB damping tail measurements.[16]

Applications: the camb_boinc2docker app

Cosmology@Home ran two applications for volunteers:

  • camb_boinc2docker - the primary and preferred application, requiring a 64-bit processor, VirtualBox 4.3 or later, and hardware virtualisation (Intel VT-x or AMD-v) enabled in the BIOS. This app packages CAMB in a Docker container and supports Windows XP or later, macOS 10.8 or later, and many recent Linux distributions.
  • camb_legacy - an older application available to volunteers whose machines do not support virtualisation. It runs only on Windows and Linux and supports 32-bit processors. Results from this app were primarily used for testing the PICO algorithm rather than for direct comparison with observational data.[7]

Technical infrastructure

Cosmology@Home ran on the standard BOINC server software stack. Millea developed boinc2docker, a package that allows any BOINC project to distribute and run Docker containers as work units, combining the capabilities of boot2docker and the BOINC vboxwrapper mechanism. This project was later generalised into the boinc-server-docker framework, which packages an entire BOINC project server as a set of Docker containers for easy deployment.[17] The project's server source code has been made publicly available.[18]

The project received support from both NASA and the Planck project.[19]

Milestones

Date Event
2007-06-30 Project launched for closed alpha testing (invitation only)
2007-08-23 Public alpha registration opened
2007-11-05 Project entered beta testing[6]
2016-12-15 Server and project moved from UIUC to the Institut Lagrange de Paris and the Institut d'Astrophysique de Paris[2][3]
2017-08 Temporary domain outage following university server migration; domain cosmologyathome.org briefly expired[9]
2022 SSL certificate lapses began preventing user logins[10]
2024 Removed from BOINC active project list; project retired from BOINCstats tracking[12]

Publications

The following papers describe the science and methods directly associated with Cosmology@Home:

  • (2007).PICO: Parameters for the impatient cosmologist. The Astrophysical Journal. pp. 2-11. DOI: 10.1086/508342.
  • (2007).Computing High Accuracy Power Spectra with Pico.

See also

References

  1. ↑ 1.0 1.1 Letter to Cosmology@Home users. Cosmologyathome.org. Retrieved 2011-02-20.
  2. ↑ 2.0 2.1 Wandelt, Ben.Welcome Letter. Cosmologyathome.org. Retrieved 2016-12-15.
  3. ↑ 3.0 3.1 Millea, Marius.(2016-12-15).Move Completed. Cosmologyathome.org. Retrieved 2016-12-15.
  4. ↑ Cosmic Microwave Background. Center for Astrophysics, Harvard and Smithsonian. Retrieved 2026-06-06.
  5. ↑ Anderson, David P..A brief history of BOINC. Retrieved 2026-06-06.
  6. ↑ 6.0 6.1 Beta testing!. Cosmologyathome.org. Retrieved 2011-02-20.
  7. ↑ 7.0 7.1 7.2 7.3 FAQ/Troubleshooting. Cosmologyathome.org. Retrieved 2022-10-05.
  8. ↑ Millea, Marius.The Cosmology@Home server (GitHub: marius311/cosmohome). Retrieved 2026-06-06.
  9. ↑ 9.0 9.1 (2017-08-16).cosmologyathome.org domain temporarily down. BOINC message boards. Retrieved 2026-06-06.
  10. ↑ 10.0 10.1 (2022-11-09).Cosmology's certificate has expired again. BOINC message boards. Retrieved 2026-06-06.
  11. ↑ Cosmology@Home. BOINC Synergy. Retrieved 2026-06-06.
  12. ↑ 12.0 12.1 (2024-10-13).Time to retire Cosmology@home. BOINCstats/BAM!. Retrieved 2026-06-06.
  13. ↑ (2007).PICO: Parameters for the impatient cosmologist. The Astrophysical Journal. pp. 2-11. DOI: 10.1086/508342.
  14. ↑ (2007).Computing High Accuracy Power Spectra with Pico.
  15. ↑ (2016).Planck 2015 results. XI. CMB power spectra, likelihoods, and robustness of parameters. Astronomy and Astrophysics. pp. A11. DOI: 10.1051/0004-6361/201526926.
  16. ↑ (2013).A Measurement of the Cosmic Microwave Background Damping Tail from the 2500 sq. deg. SPT-SZ Survey. The Astrophysical Journal. pp. 86. DOI: 10.1088/0004-637X/779/1/86.
  17. ↑ Millea, Marius.boinc2docker: Run Docker apps on a BOINC project. GitHub. Retrieved 2026-06-06.
  18. ↑ Millea, Marius.cosmohome: The Cosmology@Home server. GitHub. Retrieved 2026-06-06.
  19. ↑ Project status. Cosmologyathome.org. Retrieved 2022-10-05.

External links

Retrieved from "https://boincsynergy.ca/wiki/index.php?title=Cosmology@Home&oldid=1537"