Hi, I have something which bothers me some time and I hope some-one can relieve me from this burden. If one takes the space-time interval in Cartesian Coordinates, one gets ds2=dt2-dx2-dy2-dz2. Ofcourse we could write this in polarcoordinates etcetera. Now, if we want to describe a circular motion, some people claim that this can be done by the special theory of relativity. But, I've learned at a course GR that, if we have a force, the geodesic equation of motion should get a force-term. Carroll for instance states that if we have a charged particle with a Lorentzforce, he writes the tensorial force-term in the geodesic equation ( page 70 of his lecture notes on GR ); instead of 0 the geodesical term equals the Lorentzforce. How should we describe this case in special relativity? I see that the connectionterms become zero in flat space time and stuff, but I don't know how to proceed. Also because I'm not very familiar in describing accelerations in special relativity.