TITLE: Can a cosmic string pass through the earth undetected?
QUESTION [9 upvotes]: The metric around a straight, static and infinitely long cosmic string is flat except for the topological deficit in the angular coordinate, as described for example here. As a result, there is no gravitational force on surrounding matter. The deficit angle is also expected to be quite small, of order $10^{-6}$ radians.
My question is: what would happen if such a string was on a collision course with earth ? assuming that it interacts only gravitationally, will it simply pass through? or will there be some observable effect ?

REPLY [8 votes]: Interesting question. I found this paper:

Motohashi & Suyama, "Detecting cosmic string passage through the Earth by consequent global earthquake".  Astrophys. Space Sci. 348, 565-569  (2013).

which discusses the effects of a cosmic string passing through or near earth. The conclusion is that it will likely generate global earthquake whose magnitude depends on string tension -- from potentially catastrophic, to barely noticeable.
{"set_name": "stack_exchange", "score": 9, "question_id": 696375}