Question Inside: Handle With Care?

It is just one of the many vicious circles that result from thought experiments concerning travel in time. Back is particularly paradoxical. Many people like "Back to the Future", for example, but do not notice that if Mike's character watches himself going back in time there must be an endless number of Mikes at each point of the circle. I like Stephen Hawking's speculation that if time travel is possible where are all the visitors from the future? Since there are none it seems likely that time travel will never be invented.