conceptFEATURED CONCEPT: Dark Matter
Unlike ordinary matter, dark matter does not emit or absorb light--or any other type of electromagnetic radiation. Consequently, dark matter cannot be observed directly using a telescope or any other astronomical instrument that has been developed by humans. If dark matter has these strange properties, how do we know that it exists in the first place?
Like ordinary matter, dark matter interacts gravitationally with ordinary matter and radiation. Astronomers study the distribution of dark matter through observing its gravitational effects on ordinary matter in its vicinity and through its gravitational lensing effects on background radiation. The background image shows the bullet cluster, a famous example where the visible matter does not follow the mass distribution.
Combining all the available evidence, dark matter represents about 83% of the matter content of the universe. Read more about dark matter on this web page. Let us know your questions and comments on the message board.

User profile Profile Carlos
Proud member of team Seti.USA

Beta testing
Aug 24, 2015
Public beta testing for the new C@H is now open! Read more here.
Stats about Cosmology@Home
Jul 13, 2015
A new post containing statistics about Cosmology@Home users. Discussion here.
Website and server bug fixes
Jul 10, 2012
Kevin implemented further fixes to the web site and the server software. The participant profiles can now be browsed through the web site. Spam profiles have been removed. Upload errors should have been cured. Please test and let us know what you find.
Further updates
Jun 20, 2012
A major update has now been completed - the HTML/PHP for the website has now been updated to the latest version. This was long overdue and has hopefully closed some security loopholes. We are now cleaning out a backlog of spam user profiles, etc. Please let us know if anything is not working as expected as a consequence of these updates..
Recent updates and fixes to the project
May 6, 2012
As part of the recent updates (more storage, more recent kernel) we finally fixed a longstanding problem: the community preferences are now working again! Check out our main post on the message board for the project announcements.

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