Are closed timelike curves unphysical?

Question

Are closed timelike curves unphysical?

Answer 1

Closed timelike curves? Are you talking about the shape of space or the universe?

Sorry, need more information.

Answer 2

I don't understand what you mean by "unphysical".  However, a Closed Timelike Curve is theoretical.  It is not known if they exist or not.  

A Closed Timelike Curve is a world line of an object that returns to its starting point (meaning; the beginning is the end and the end is the beginning, like a circle).  

Also, the "world line" is, in physics, the unique path that an object takes through 4-dimensional spacetime.