# What would happen if a negative mass crossed the event horizon of a black hole?

If negative mass really existed and somehow a very fast traveling negative mass object reached near the black hole's event horizon.

What would happen when it crosses the event horizon? According to Newton's law the negative mass should be repelled and only an object that can travel faster than light can escape a black hole. So, will the object be ejected out of the event horizon with a speed greater than light and that would lead to the object's mass becoming -∞ (minus infinity) according to theory of relativity and disobey laws of physics as we know it.

Any Explanations?

• (continued) "Thus the two masses will experience equal forces and accelerations in the same direction (in violation of Newton's third law) and the system of two particles will accelerate, seemingly without limit. The negative mass will chase the positive mass with constant acceleration." I would quibble with Cramer's statement that this violates Newton's third law though, since it's still true that $m_1 a_1 = - m_2 a_2$--the force vectors do point in opposite directions, it's just that the negative mass accelerates in the opposite direction of its force vector. Dec 15, 2014 at 18:32