Numerous arguments
are proposed that prevent time travel into the past. Both common
sense and scientific fact
construct serious obstacles. A major argument against time travel
into the past is called the autonomy principle,
better know as the grandfather paradox. This paradox is created
when a time traveler goes back in time to meet his
or her grandfather. Now, upon their introduction it would be
possible to change the course of events that lead up to
your grandfather and grandmother marrying. You could tell him
something about a family secret to convince him
you are who you say you are, and he may proceed to tell his soon
to be wife. She may in turn doubt his sanity and
have him committed. Thus your grandparents would never have had
your mother, and therefore you couldn't be born!
But then how could you have ever existed to travel back in time
if you don't exist? The next question would be, if your mother
was never born, then when you return to the
future would anything you did in your life exist? Or would you,
your friends, your home etc. never have existed?
This is clearly a paradox that would rule out time travel. Yet,
interestingly enough, the laws of physics
do not forbid such excursions. The multiverse concept eradicates
the problem of the autonomy principal, because it
allows time travel to the past, but to a different universe.
You would meet the person who was your grandfather in
your universe, but never married your grandmother in his universe.
In the universe that you traveled to, you never
existed.
Another argument of
impossibility is called the chronology principal. This principal
states that time travelers could
bring information to the past that could be used to create new
ideas and products. This would involve no creative
energy on the part of the "inventor." Imagine that
Pablo Ruiz y Picasso, the most influential and successful artist
of
the 20th century, were to travel back in time to meet his younger
self. Assuming he stays in his correct universe, he
could give his younger self his portfolio containing copies of
his paintings, sculptures, and ceramics.
The young version of Picasso could then reproduce the copies,
profoundly and irrevocably affecting
the future of art. Thus, the reproductions exist because they
are copied from the originals, and the originals exist
because they are copied from the reproductions. So, where does
the creative knowledge come from that caused the creation of
the artwork?
Consider the following
odd scenario. In 1966 Jennifer, an orphaned
girl of 16, meets a vagabond, Roger, along the road. They start
talking, and after a
while Jennifer seems to be pregnant. Roger disappears without
her knowing his
name. Nine months later, due to complications with the birth,
Jennifer needs to
change sex. Her child is also robbed from the hospital. Twenty
years later Jennifer,
now known as Roger, is poor and survives as vagabond. In 1986
in a bar, after a
couple of drinks, Roger tells his story to the bartender, who
has got an
interesting proposition: he gives Roger the opportunity to travel
back in time and take
revenge on the vagabond that made him/her pregnant. Therefore
he has to join the
secret organization of time travellers. Roger accepts, but when
he arrives in 1966,
he meets a girl, Jennifer. He makes her pregnant, doesn't find
the vagabond and
begins a bar. He joins the secret organization of time travellers
and talks to the
vagabond in 1986. The bartender disappears and travels to 9 months
after 1966 to
steal Jennifer's child, a girl, out of the hospital so Jennifer
doesn't have to raise it on
her own. He brings her 16 years back in time, to 1950, where he
leaves her in an
orphanage.
An odd paradox, because
Jennifer is her own mother, father, grandma, grandpa, son, daughter,
grandson and
granddaughter.