text: The hard problem is often illustrated by 
  appealing to the logical possibility of inverted 
  visible spectra. If there is no logical 
  contradiction in supposing that one's colour 
  vision could be inverted, it follows that 
  mechanistic explanations of visual processing 
  do not determine facts about what it is like to 
  see colours. 
  
  Chalmers's 
  idea contradicts physicalism, sometimes 
  labelled materialism. This is the view that everything that 
  exists is a physical or material thing, so everything can 
  be reduced to microphysical things. For example, the 
  rings of Saturn are a physical thing because they are 
  nothing more than a complex arrangement of a large 
  number of subatomic particles interacting in a certain way. 
  According to physicalism, everything, including consciousness, 
  can be explained by appeal to its microphysical constituents. 
  Chalmers's*hard problem*presents a counterexample to this view 
  and to other phenomena like swarms of birds, since it suggests that 
  consciousness, like swarms of birds, cannot be reductively 
  explained by appealing to their physical constituents. Thus, if the 
  hard problem is a real problem then physicalism must be false, and 
  if physicalism is true then the hard problem must not be a real 
  problem. 
  
  A swarm of birds showing high 
  order structure emerging from 
  simpler physical constituents 