Challenging 'accepted' theories

Theoretical constructs that were written off as impossible can exist

One of the cardinal rules of science is that every hypothesis is open to experimental testing, and to being discarded or radically modified upon contradictory results. Sometimes a theory is accepted for centuries. For example, Newton’s Laws were accepted until Einstein came along, 250 years later. 

Some things go unchallenged for so long that it is a shock to learn that they require modification. Mass and absolute zero are two things that every school child is taught to be intrinsic: Every object has mass; atoms stop moving at absolute zero.  

Both notions have been challenged in the recent past