http://www.forbes.com/sites/startswithabang/2016/11/30/could-dark-matter-be-powering-the-emdrive/#570d02311e53? My answer to this is spacetime that is travelling faster than the speed of light is composed of dark matter and travels less than 500000km/s.In actuality,dark matter are particles ,whose square of mass is negative and hence, they can exceed the speed of light., according to revised special theory of relativity, the link of which is https://www.researchgate.net/post/Spooky_action_at_a_distanceWas_Einstein_wrong
https://www.researchgate.net/post/Spooky_action_at_a_distanceWas_Einstein_wrong