This detection above may be described as, just talk and after some time you will know if other computers talk at same time as you. But due to communication of light, will it never be possible to know without delays if multiple devices communicates simultanously and take up the medium. After a time t, may the collision be detected, and both know that they actualy may have destructed eatch others data. Any destructed data, takes up of the speed of network. The idea above is to use a collision based binary decission three, and also use that people increase their patience after they have succeed something to say.
Some collision based newworks works randomly.
The networks described above have full troughput guarentee, and are for any medium at earth.