This statement goes at the heart of Newton's third law of physics, for
every action there is an equal and opposite reaction. When a
normal person does a push up, they exert a force on the Earth and the
Earth exerts an equal force on them which pushes that person up.
For the forces to be equal and opposite, they must hold to Newton's
second law F=ma. If the average person were to do a push up, they
accelerate the Earth down, but the earth is so massive that it hardly
moves. It is its massive size that keeps the Earth from moving
when people move about on the blue planet.
While the original statement is true for everyone, as
everyone moves the earth by nearly immeasurably small amounts, for the
claim to hold any significant water it must be assumed that Norris
causes the Earth to move in a noticable fashion. or Chuck Norris,
he legitimately does push the earth down. That is to say that the
earth accelerates very quickly away from him. In order for this
to make sense, his mass must be drastically larger than that of the
Earth's. That is, he is much larger than 5.97 x 1024
kg.