When we kept the Earth's mass the same, but shrank its size, we saw that had an effect on its escape speed. Albert Einstein used to perform what he called "thought experiments". Let's do a thought experiment in which the Earth's mass stays the same, but we keep packing that mass into a smaller and smaller size. Would we ever get to a point where there is no possible way for a spacecraft to escape the Earth? If so, why? (Hint: There's an important fact in Chapter 1 which is relevant to answering this question correctly.)