A vessel containing oxygen and hydrogen gases can exist indefinitely without exploding because the reaction between oxygen and hydrogen requires an activation energy to initiate the reaction.
A vessel containing oxygen and hydrogen gases can exist indefinitely without exploding because the reactants require an activation energy to overcome their energy barrier and initiate the explosive reaction.
A vessel containing oxygen and hydrogen gases can exist indefinitely without exploding because in order for a reaction to occur, there must be sufficient activation energy provided, which may be lacking in the absence of a spark or flame.