'proof' is a term only used in mathematics
do you remember proving therums in geometry?

'proof' is not used in science
there is compelling evidence to believe the laws of gravity, motion, etc are valid (true) until another theory comes along which displaces it.
aristolian science was accept as law until it was replaced by newtonian science and now the theories of einstein are accepted as valid BUT they are NOT PROVED

anyone seeking 'proof' of life after death will not get it
what they will get is an overwhelming body of compelling evidence which supports the theory of life after death