Perhaps this is a question better suited for the physics exchange but maybe someone here would know. I was reading Ender's Game and I was trying to imagine what would happen physically after the Little Doctor was used.

That is, after the fornic planet is ripped into bits molecule by molecule what would a physicist expect all of that matter to do after the chain reaction has completed. Would the molecules fall back into a lump of planet or collapse into a star or something?

Also, in the book they say that there is no radiation with this reaction. Is it even imaginably feasible for a device to pull apart molecules without releasing radiation?

I don't know much about physics but the question has piqued my interest.

Thanks in advance.

closed as off-topic by Gallifreyan, phantom42, Adamant, NKCampbell, Dave Johnson Jun 23 '17 at 19:04

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    I do recall the actual physics of how the Doctor Device works being discussed in 'Ender in Exile', and that it works with similar principles to the ship drives that were adapted from captured Formic technology. Though I don't remember enough details to go further into it. – onewho Jun 23 '17 at 16:10
  • I think you're right in thinking that this question is more suited for Physics, because it's more about real physics, than what actually occurred in the novel. – Gallifreyan Jun 23 '17 at 16:22
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    Indeed the debris after sufficient time would recollapse and form a planetoid or maybe an asteroid belt, but definitely not a star (the planet was never massive enough in the first place). Also, the time scale for the recollapse is in the order of a few million years. I also agree that this question should be migrated to the Physics stack. – Rebel-Scum Jun 23 '17 at 16:26
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    That is true, but there is also the meta policy. – Gallifreyan Jun 23 '17 at 16:28
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    Radiation released (at least on my limited HS physics knowledge) is dependent on how much mass is preserved and how much is converted to energy (there has to be some - atoms / molecules wouldn't get momentum to fly apart from nowhere). – Radhil Jun 23 '17 at 17:20

I am not a physicist, the following is only what I have discovered in my own research.

It would probably become an asteroid belt, but could reform into a planet, given enough time.

According to Ender's Game, the Molecular Disruption Device created a field in which electrons could not be shared. After the field died down, the only thing remaining would be a clump of iron molecules.

Since it just tore everything apart into molecules, we basically have an iron gas left over. After thousands to tens of thousands of years later, you'll have asteroids. Assuming the star is still there, they will likely get spread out in an orbit around the star, thus forming a belt.

The following blockquote explains how gas interacts around a star up to the point of becoming a planet.

If a disk [of gas around a star] does not collapse due to its own gravity, small dust grains in the disk will start to grow as they collide into each other, just like how dust bunnies are formed in the corners of a room. When temperature drops below freezing temperature, ices start to form on the surface of dust grains, making them more sticky and easier to grow. Eventually, dust particles grow from micrometer size, smaller than the diameter of a hair to pebbles, boulders, and kilometer-size planetesimals (a few miles). Once reaching a few kilometers in size, planetesimals become heavy enough to attract more dust and other planetesimals around them, and they start to grow very rapidly into planets. If they grow large enough, they can also attract gas and become gas giants.
How long does it take for a planet to be born?

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