What would happen if gravity became 5 percent stronger right now? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.
What would happen if gravity became 5 percent stronger right now?
Other answers massively underestimate the gravity of this situation. This is a clear "everyone dies" scenario.
On second thought, maybe I should say "everyone fries" instead. This is pretty cataclysmic. Anyway, the point is that humans won’t make it very long.
Let’s start with the effect on the earth’s orbit around the sun. An orbit is a delicate balance between gravity, which pulls a planet toward its star, and the planet’s velocity, which tends to carry it away into space. A sudden change in gravity disrupts the balance, resulting in Earth moving into a new, tighter elliptical orbit. At its closest, Earth will pass about 9% to 10% closer to the sun than it does today. (You can find the exact number using the vis-viva equation — it depends on where Earth is in its orbit when the laws of physics change.)
That should be enough to trigger catastrophic climate change, leading to widespread famines and probably the collapse of the global economy, but it might not kill everyone.
The next thing to consider is the impact on the sun. The sun also hangs in a balance: the pressure from the hot plasma in the interior tries to tear it apart, while gravity pulls it together. Again, a sudden change in the strength of gravity disrupts this equilibrium. Hydrogen gas from the sun’s surface falls toward the core, fusing into helium and explosively releasing vast amounts of energy.
Is this enough to kill all life on Earth? I’m not entirely sure. As in a helium flash, most of the energy released gets converted into heat and doesn’t reach the sun’s surface. In the most optimistic scenario, we might not notice anything at all here on Earth.
In fact, the increase in gravity does its worst damage deep beneath the earth’s surface. The earth’s core bears an immense load: the entire weight of our planet, about 6.6 x 10 21 tons of rock. Thanks to the new gravitational constant, all of this rock suddenly becomes 5% heavier. Unable to carry the extra burden, the core collapses inward, causing the rest of the planet to fall down on top of it.
A quick estimate suggests that the surface might drop only about 10–20 km, but the exact number doesn’t matter so much: "everyone dies", either directly in the fall or shortly afterwards from the heat released as the crust buckles and collapses.
Depending on the details of the collapse process, it’s conceivable that the entire surface of the planet could melt.
Conclusion: don’t mess with gravity.
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