You may remember my question here, part of which assumed that all humans would die in one way very quickly, with minimal destruction to the planet.

This question will ask about the way humans would die:

We all know about water's phase changes.

Let's say that the core of the Earth overheated, sending heat waves upward to the surface. The heat vaporizes most of the water, sending gas (steam) into the atmosphere. The gas pushes out most of the air into space and only steam remains. This effectively wipes out the human race in hours.

After hundreds of years, the steam contracts back onto the surface of the planet after Earth's core cools down due to human inactivity¹.

Is this a plausible theory? Could it actually work if Earth overheated?

Some quick diagrams made by me:

Before overheating of Earth: enter image description here Overheating: enter image description here

¹As pointed out in comments, humans probably couldn't affect the Earth's core, but just assume it did for the moment.

I am relying on little knowledge in the scientific field so just tell me if I am being an idiot and my theory is bonkers.

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    $\begingroup$ I think you are underestimating, by several orders of magnitude, the power that would be needed to "evaporate all of the water in a few hours". That kind of power would easily kill all of the humans in minutes, by itself. $\endgroup$
    – SJuan76
    Feb 1, 2021 at 20:57
  • $\begingroup$ @SJuan76 True, but I need it to work this way so, in the end, the atmosphere is a void of nothing (no gasses or elements). $\endgroup$ Feb 1, 2021 at 20:58
  • $\begingroup$ Argon, radon, helium ...etc. are constantly being leaked from the core always, are you also trying to prevent this? Are you just looking for an Earth sized planed with some scattered H-2O around and no party-atmosphere, like the Moon but bigger? $\endgroup$ Feb 1, 2021 at 21:02
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    $\begingroup$ @Tantalus'touch. I am trying to prevent as many gasses as possible from being in the atmosphere. I understand that some are impossible to eliminate in this scenario, which is fine. Assume that the planet is Earth. $\endgroup$ Feb 1, 2021 at 21:05
  • $\begingroup$ @Nai45 Does it need to be sudden or can it be gradual? A collapse of the earth’s magnetic field should leave the atmosphere vulnerable to solar rays stripping away the atmosphere. Given enough time earth should be mostly atmosphereless. $\endgroup$ Feb 1, 2021 at 21:22

1 Answer 1


No, gases generally do not displace each other. A concentrated heavier gas may pool at the bottom and displace lighter gases - but water vapor is lighter than most atmospheric gases. A gas coming out from a high pressure container can push other gases aside - but in this scenario we have no high pressure container.

Higher temperature would accelerate the loss of atmosphere to space - but water would be lost first.

  • $\begingroup$ But couldn't the atmosphere serve as a high-pressure container? It may not be small but it definitely has high pressure. $\endgroup$ Feb 1, 2021 at 21:37
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    $\begingroup$ @Nai45 - evaporating water would be subject to the same pressure as the atmosphere itself, so the vapor won't be able to push gases away. Even if there was such a push, it could be sustained only for a short period of time, because heavier atmospheric gases would diffuse back to the surface. $\endgroup$
    – Alexander
    Feb 1, 2021 at 21:47
  • $\begingroup$ True, thank you! $\endgroup$ Feb 1, 2021 at 21:57

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