Consider for example, if you get a heart attack and die today.
Without referring to any history book:
Your dotor can do an autopsy and know:
a) Your diet during your living year by studying your blood contend
b) Your cause of death
c) Your real parents (if differ from record)
d) Any major injury you have during your life
e) The approximate dates you live
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In the future, even if the world is conquered by alien, they can dig on the ground:
a) Find the remain of the server of Exchristian site and observe your thoughts, from the content of the forum as much as from the technical of the site
b) Find your living quarter and personal item and gain an insight to how you may live. For example how many woman live in your quarter and what is their relationship to you
c) If you fight a battle, they can dig up the grave and see how many you kill, and how you kill them
d) If you are the governor of HKSAR, they will see your signature on the document. If you are director of HKMA, they will see your signature on the bill
e) If you have a children, DNA study can show what approxi mutation you have passed to your children
There is many way history can be known refering to only nothing but objective physical evidence. Anyone can know a camel passed over the desert when he see the footprint. If there is really a global flood, there will be water mark everywhere.
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It is ONLY another branch of science. "History is written by the victor" is only a misunderstanding on how history is written in mordern time.
Rather, it is "History is intepreted by the survivors." (You only need to be fit to survive, there is no need to be the victor. Luxemburg will have its own history of Germany whether or not it is the victor as long as it survives.)