How bad is the situation? Have our known laws of gravity failed us? They certainly work within the solar system. Newton showed that you can derive the unique speed that a planet must have to maintain a stable orbit at any distance from the Sun, lest it descend back toward the Sun or ascend to a farther orbit. Turns out, if we could boost Earth’s orbital speed to more than the square root of two (1.4142 . . .) times its current value, our planet would achieve “escape velocity,” and leave the solar system entirely. We can apply the same reasoning to much larger systems, such as our own Milky Way
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