Preface（第1页）

Preface

Thisisabookabravityiswhatcausesmassiveobjectstofalltowardseachother。It'sgravitythatcausesapplestofallfromtrees，anditwasgravitythatcausedtheEarthtravityisthemostfamiliarofallthefualforature，yetthetruewayinwhichgravityworksisfarfromobvious。Ihepheoas‘gravity’isdeeplytiedupwiththenatureofspadtime。Thismeansthatamoderandingofgravitydoesn’tjusttellushowobjetheUalsoallowsustouhebehaviouroftheveryspadtimethatmakeupthefabricoftheUself。

Thepurposeofthisbookistogivethereaderaverybriefintrodutovariousdiferesofgravity。Westartbylookingatthewayinwhichthetheravitydevelopedhistorically，befontoanoutlineofhowitisuoodbystiststoday。WewillthehecesofgravitationalphysitheEarth，intheSolarSystem，andintheUniverseasawhole。Thefinalchapterdeseofthefrontiersoftreseartheravitationalphysics。

Bytheeohaveveyedtothereadernotonlywhatgravityis，buthowthestudyofgravityhasledstiststoreachextraordinarysaboutthenatureofspace，time，andtheUniverseinwhichwelive。