▁such ▁as ▁quantum ▁tele port ation , ▁the ▁E PR ▁par ado x , ▁or ▁quantum ▁ent ang lement ▁might ▁appear ▁to ▁create ▁a ▁mechanism ▁that ▁allows ▁for ▁faster - than - light ▁( FT L ) ▁communication ▁or ▁time ▁travel , ▁and ▁in ▁fact ▁some ▁interpret ations ▁of ▁quantum ▁mechan ics ▁such ▁as ▁the ▁Boh m ▁interpretation ▁pres ume ▁that ▁some ▁information ▁is ▁being ▁ex changed ▁between ▁particles ▁instant ane ously ▁in ▁order ▁to ▁maintain ▁correl ations ▁between ▁particles . ▁This ▁effect ▁was ▁referred ▁to ▁as ▁" sp ook y ▁action ▁at ▁a ▁distance " ▁by ▁Ein stein . ▁ ▁Nevertheless , ▁the ▁fact ▁that ▁caus ality ▁is ▁preserved ▁in ▁quantum ▁mechan ics ▁is ▁a ▁rig orous ▁result ▁in ▁modern ▁quantum ▁field ▁theories , ▁and ▁therefore ▁modern ▁theories ▁do ▁not ▁allow ▁for ▁time ▁travel ▁or ▁F TL ▁communication . ▁In ▁any ▁specific ▁instance ▁where ▁F TL ▁has ▁been ▁claimed , ▁more ▁detailed ▁analysis ▁has ▁proven ▁that ▁to ▁get ▁a ▁signal , ▁some ▁form ▁of ▁classical ▁communication ▁must ▁also ▁be ▁used . ▁The ▁no - communic ation ▁theorem ▁also ▁gives ▁a ▁general ▁proof ▁that ▁quantum ▁ent ang lement ▁cannot ▁be ▁used ▁to ▁transmit ▁information ▁faster ▁than ▁classical ▁signals . ▁ ▁Inter act ing ▁many - world s ▁interpretation ▁ ▁A ▁variation ▁of ▁Ever ett ' s ▁many - world s ▁interpretation ▁( M WI ) ▁of ▁quantum ▁mechan ics ▁provides ▁a ▁resolution ▁to ▁the ▁grand father ▁par ado x ▁that ▁involves ▁the ▁time ▁travel er ▁arriv ing ▁in ▁a ▁different ▁universe ▁than ▁the