The discussion revolves around the astronomical discrepancies presented in the film "Men In Black 2," particularly focusing on the feasibility of blowing up a planet as depicted in the movie. Participants explore the calculations involved in such a scenario, including the energy required and the factors that influence these calculations, such as the planet's mass and radius.
Participants generally agree on the complexity of the calculations involved in determining the energy required to destroy a planet, but there is no consensus on the specifics of how planet size factors into these calculations. The discussion remains unresolved regarding the exact dependencies and calculations.
Limitations include the lack of specific mathematical details in the discussion and the reliance on external sources for calculations that some participants could not access.
Readers interested in the intersection of astronomy and popular media, as well as those curious about the scientific principles behind fictional representations of astronomical phenomena.
Bad:
In the beginning, we see a montage of aliens blowing up planets. A beam weapon is fired, and the planets explode in giant pieces.
Good:
It's really hard to blow up a planet! It's possible that the alien technology did something like cause a chain reaction which totally disintegrated the atoms, or something like that.
But that's no fun. Well, it might be fun, but really, how much energy does it take to blow up a planet? I did this calculation once before, to show that a comet impact could not destroy a planet. To blow up a planet, you have to overcome the gravity of the planet for each piece. Let's put it another way: Imagine taking a rock and throwing it up so hard it escapes from the planet entirely. For the Earth, that means you have to give it a pretty big velocity, about 11 kilometers per second. It takes a lot of energy to do that, the amount of which depends on the mass of the rock and the amount of gravity you are fighting. Now take another rock, and do it again. And again. And againandagainandagain. Repeat for a gazillion times. If you do it enough times, the planet is gone. You've destroyed it. Congratulations!
It's possible to calculate that total energy you expended. It's called the gravitational binding energy, and is basically the amount of energy locked up in the planet's gravity. I'll spare you the math (but you can find it here if you'd like), but for the Earth that energy is roughly 1039 ergs. An erg is a tiny unit of energy, but 1,000,000,000,000,000,000,000,000,000,000,000,000,000 is a lot of them! For comparison, the Sun puts out about 4 x 1033 ergs every second, so the amount of energy needed to vaporize the Earth is about the total amount of energy the Sun emits in 3 days! That's a whole lot of energy. I doubt a single ship could generate that much. But who knows? They're aliens!
Yes, if by 'size' you mean mass. There's also a 'radius' dependency.Originally posted by SquareItSalamander
This excerpt is from badastronomy.com concerning the beginning of Men In Black 2. My question is, do the calculations depend on the planet's size?
Did you find?"I'll spare you the math (but you can find it here if you'd like) ..."
Originally posted by Nereid
Did you find? [/B]