CosmicOS is a way to create messages suitable for communication across large gulfs of time and space. It is inspired by Hans Freudenthal's language, Lincos, and Carl Sagan's book, Contact. CosmicOS, at its core, is a programming language, capable of expressing simulations. Simulations are a way to talk, by anology, about the real thing they model.
CosmicOS is structured to communicate the usual math and logic basics, then use that to show how to run programs, then send interesting programs that demonstrate behaviors and interactions, and start communicating ideas through ”theater” and simulations. This is inspired by Freudenthal's idea of staging conversations between his imaginary characters Ha and Hb.
Traditionally, CosmicOS has been represented as a long sequence of four symbols. Labeling them arbitrarily as 0, 1, 2, and 3, the message begins like this:
Estimating message entropy by compressing this message, we get: 25 kB. This message form has some major revisions pending to ease comprehension. Please be forgiving. It'll all get fixed in an instant of galactic time.
The message is organized as follows:
The message uses the following syntax (shown in plaintext form):
symbol meaning ( marks beginning of an expression ) marks end of an expression  opens a parenthesis which will selfclose at the next parenthesis. (A B  C  D) is another way to write (A B (C (D))). This greatly simplifies complex expressions. $ $A is shorthand for (A). ; marks end of a statement
There are also numbers and arbitrary symbols. If there's no other syntax between two of these, they must be separated from each other by whitespace. How all of this is encoded is subject to change. Originally, CosmicOS converted all arbitrary symbols into numbers, and encoded numbers in binary. The message will remain compatible with this, but the encoding of symbols is being changed.
I've chosen the GPL for whimsical reasons. If it is a problem for you just file an issue. I'm a license pushover.
 The CosmicOS software is licensed under the CCGNU GPL. 

The CosmicOS webpages are licensed under a Creative Commons AttributionShareAlike 2.5 License. 