Full Idea
String theory suggests that space-time has a grainy substructure - you can't keep chopping it indefinitely into smaller and smaller pieces.
Gist of Idea
In string theory space-time has a grainy indivisible substructure
Source
New Scientist writers (New Scientist articles [2013], 2015.11.07)
A Reaction
Presumably the proposal is that strings are the true 'atoms'.
Book Reference
-: 'New Scientist magazine' [ 2013], p.32