mysteryman on 19 December 2013
Assumptions are necessary, as we simply aren't at the point of understanding the overwhelmingly large set of minutia regarding interactions that affect everything in the universe. However, that is not to say that using assumptions makes science less factual. As we further research, expand our knowledge-base and ultimately further understand the situation/interaction etc. that we are analysing theoretically, the assumptions used can be refined.
But, as said above, don't take anything said on the discovery/science channel as gospel.
