( ( ( ( ( ( As ( you ( ( blow up ) ( the balloon ) ) ) ) ( , ( ( its radius ) ( increases ( in time ) ) ) ) ) , ) and ) ( ( ( the volume ) ( of ( space ( represented ( by ( its ( stretching surface ) ) ) ) ) ) ) ( represents ( how ( ( ( the ( 3-dimensional space ) ) ( of ( our universe ) ) ) ( is ( ( stretching ( to ( ` ( ( create ' ) ( more space ) ) ) ) ) ( as ( ( the universe ) ( expands ( in time ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (SBAR (IN As) (S (NP (PRP you)) (VP (VB blow) (PRT (RP up)) (NP (DT the) (NN balloon))))) (, ,) (NP (PRP$ its) (NNS radius)) (VP (VBZ increases) (PP (IN in) (NP (NN time))))) (, ,) (CC and) (S (NP (NP (DT the) (NN volume)) (PP (IN of) (NP (NP (NN space)) (VP (VBN represented) (PP (IN by) (NP (PRP$ its) (JJ stretching) (NN surface))))))) (VP (VBZ represents) (SBAR (WHADVP (WRB how)) (S (NP (NP (DT the) (JJ 3-dimensional) (NN space)) (PP (IN of) (NP (PRP$ our) (NN universe)))) (VP (VBZ is) (VP (VBG stretching) (S (VP (TO to) (VP (`` `) (VB create) ('' ') (NP (JJR more) (NN space))))) (SBAR (IN as) (S (NP (DT the) (NN universe)) (VP (VBZ expands) (PP (IN in) (NP (NN time)))))))))))) (. .)))
As you blow up the balloon, its radius increases in time, and the volume of space represented by its stretching surface represents how the 3-dimensional space of our universe is stretching to 'create' more space as the universe expands in time.
(ROOT (S (PP (IN From) (NP (NP (NNS observations)) (ADJP (RB as) (JJ simple) (PP (IN as) (S (VP (VBG blowing) (PRT (RP up)) (NP (DT a) (NN balloon)))))))) (, ,) (NP (PRP it)) (VP (VBZ is) (ADJP (JJ clear)) (SBAR (IN that) (S (S (VP (VBG increasing) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN gas)))))) (VP (VBZ increases) (NP (DT the) (NN volume)))))) (. .)))