( ( At ( speeds ( close ( to ( that ( of light ) ) ) ) ) ) ( , ( reality ( ( is ( very different ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (NP (NNS speeds)) (ADJP (VBP close) (PP (TO to) (NP (NP (DT that)) (PP (IN of) (NP (NN light)))))))) (, ,) (NP (NN reality)) (VP (VBZ is) (ADJP (RB very) (JJ different))) (. .)))
At speeds close to that of light, reality is very different.
(ROOT (S (NP (JJ Different) (NNS media)) (VP (VBP affect) (NP (NP (DT the) (NN speed)) (PP (IN of) (NP (NN light))))) (. .)))