[转载]什么是“祖父悖论”？The&Grandfather&Paradox
什么是“祖父悖论”？The Grandfather Paradox
是一种时间旅行的悖论：假设你回到过去，在自己父亲出生前把自己的祖父母杀死；因为你祖父母死了，就不会有你的父亲；没有了你的父亲，你就不会出生；你没出生，就没有人会把你祖父母杀死；若是没有人把你的祖父母杀死，你就会存在并回到过去且把你的祖父母杀死，于是矛盾出现了。
The grandfather paradox is a proposed
described (in this exact form) by the science fiction writer
in his 1943 book Le Voyageur Imprudent (Future Times
The paradox is described as following: the time traveller went back
in time to the time when his or her grandfather had not married
yet. At that time, the time traveller kills his or her grandfather,
and therefore, the time traveller is never born when he or she was
meant to be.
Despite the name, the grandfather paradox does not exclusively
regard the impossibility of one's own birth. Rather, it regards any
action that makes impossible the ability to travel back in time in
the first place. The paradox's namesake example is merely the most
commonly thought of when one considers the whole range of possible
actions. Another example would be using scientific knowledge to
invent a time machine, then going back in time and (whether through
murder or otherwise) impeding a scientist's work that would
eventually lead to the very information that you used to invent the
time machine. An equivalent paradox is known (in ) as
autoinfanticide, going back in time and killing oneself as a
The grandfather paradox has been used to argue that backwards
impossible.[] However, a number of hypotheses have
been postulated[] to avoid the paradox, such as the idea
that the past is unchangeable, so the grandfather must have already
survived the attempted killing (as stated earlier); or the time
traveller creates - or joins - an alternate time line
in which the traveller was never born.
(1943). Le voyageur imprudent ("The imprudent
traveller").; actually, the book refers to an
ancestor of the time traveler not his grandfather.
(1987). Asymmetries in Time. Cambridge, MIT Press.
When the term was coined[] by , he
used the term autofanticide.
See also , , published in 1958, just the year
following 's Ph.D
&the time travel paradoxes
&The paradoxes of time travel
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Grandfather Paradox :
Time travel is impossible as exemplified by the famous grandfather
Imagine you build a time machine.
It is possible for you to
travel back in time, meet your grandfather before he produces any
children (i.e. your father/mother) and kill him.
Thus, you would not
have been born and the
would not have been built, a
Perhaps the craziest of the time travel paradoxes was
cooked up by Robert Heinlein in his classic short story "All You
A baby girl is mysteriously dropped off at an orphanage in Cleveland in
1945. "Jane" grows up lonely and dejected, not knowing who her parents
are, until one day in 1963 she is strangely attracted to a drifter. She
falls in love with him. But just when things are finally looking up for
Jane, a series of disasters strike. First, she becomes pregnant by the
drifter, who then disappears. Second, during the complicated delivery,
doctors find that Jane has both sets of sex organs, and to save her life,
they are forced to surgically convert "her" to a "him." Finally, a
mysterious stranger kidnaps her baby from the delivery room.
Reeling from these disasters, rejected by society, scorned by fate, "he"
becomes a drunkard and drifter. Not only has Jane lost her parents and her
lover, but he has lost his only child as well. Years later, in 1970, he
stumbles into a lonely bar, called Pop's Place, and spills out his
pathetic story to an elderly bartender. The sympathetic bartender offers
the drifter the chance to avenge the stranger who left her pregnant and
abandoned, on the condition that he join the "time travelers corps." Both
of them enter a time machine, and the bartender drops off the drifter in
1963. The drifter is strangely attracted to a young orphan woman, who
subsequently becomes pregnant.
The bartender then goes forward 9 months, kidnaps the baby girl from the
hospital, and drops off the baby in an orphanage back in 1945.
bartender drops off the thoroughly confused drifter in 1985, to enlist in
the time travelers corps. The drifter eventually gets his life together,
becomes a respected and elderly member of the time travelers corps, and
then disguises himself as a bartender and has his most difficult mission:
a date with destiny, meeting a certain drifter at Pop's Place in 1970.
The question is: Who is Jane's mother, father, grandfather, grand mother,
son, daughter, granddaughter, and grandson? The girl, the drifter, and the
bartender, of course, are all the same person. These paradoxes can made
your head spin, especially if you try to untangle Jane's twisted
parentage. If we drawJane's family tree, we find that all the branches are
curled inward back on themselves, as in a circle. We come to the
astonishing conclusion that she is her own mother and father! She is an
entire family tree unto herself.
Excerpt from the Encyclopedia Britannica without permission.