( Therefore ( , ( ( in ( the past ) ) ( ( the ( radiation density ) ) ( ( ( was ( much larger ) ) ( relative ( to ( the ( matter density ) ) ) ) ) . ) ) ) ) )
(ROOT (S (ADVP (RB Therefore)) (, ,) (PP (IN in) (NP (DT the) (NN past))) (NP (DT the) (NN radiation) (NN density)) (VP (VBD was) (ADJP (RB much) (JJR larger)) (ADVP (JJ relative) (PP (TO to) (NP (DT the) (NN matter) (NN density))))) (. .)))
Therefore, in the past the radiation density was much larger relative to the matter density.
(ROOT (S (NP (NNP Density)) (VP (VBZ describes) (SBAR (WHADJP (WRB how) (JJ much)) (S (NP (NN matter)) (VP (VBZ is) (PP (IN in) (NP (NP (DT a) (JJ certain) (NN amount)) (PP (IN of) (NP (NN space))))))))) (. .)))