Does space have a physical role in the "jerk" of acceleration? This "jerk" that the great Einstein talks about in his book is really confusing me. Without space, there seems not to be a medium through which matter can move, thusing allow it (matter) to make sense of "force." I'll use one golden retriever in this example. Her name is Isabelle. Isabelle is suspended in deep, deep space. Suddenly she turns on her rocket booster. She accelerates. Okay, now she feels this "jerk" Einstein talks about. From my understanding, this is a "force." Gravity (force of nature) is equivalent to acceleration. Okay, but what role does space (maybe spacetime) have in the golden retriever's feeling of this jerk? The easy answer is: without space, nothing exists. I accept that. I'm just wondering if space has some unacknowledged role in the "jerk" matter feels when it is accelerated or decelerated. Or does space play no physical role in this?