Grandfather Paradox
Recently, I have been reading physics books of Michio Kaku, a very popular physicist, and these books make me wonder a lot. Sometimes I even have to bring back myself from tiny world of quantum particles to our every day world.
Is time travel possible? According to Kaku, there is no known law of physics that preventing us from traveling back in time. But obviously there are many limitations and problems we have to solve before we can actually travel back in time. Otherwise, We should have already seen many eager time traveler lining up to go visit their grandparents.
One interesting paradox related to time travel is called grandfather paradox. Suppose you go back in time and kill your grandfather before he get a chance to meet your grandmother. What will happen to you? Can you really go back to time and actually kill your grandfather? If you killed your grandfather in the past, you never existed, so how can you go back in time and kill your grandpa? You don’t necessarily go back and kill your grandpa:)
There can be more complex problems occur. I found the following video on youtube. Kaku himself talks about the paradox. enjoy!
–soe