Cosmic Strings

Cosmic Strings are a pair of strings which are believed to be formed due to the defects in universe after the big bang.

Cosmic strings move in the first dimension with no breadth and only length. If any object passes from between these , it can travel to past or future.

This sounds very interesting but if you travel into the future or past , you cannot come back to the present.

It was proved when two quasars appeared at the same time in the night sky but it still is a hypothetical object.