( ( Space ( with ( lesser density ) ) ) ( ( attracts ( matter ( of ( greater density ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Space)) (PP (IN with) (NP (JJR lesser) (NN density)))) (VP (VBZ attracts) (NP (NP (NN matter)) (PP (IN of) (NP (JJR greater) (NN density))))) (. .)))
Space with lesser density attracts matter of greater 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))))))))) (. .)))