Would life as we know it exist on earth if ice sank instead of floated?
My understanding is that the Earth would be a big ice ball.
I recall a teacher in high school or college asking that question in physics class one day. It was rhetorical and he was just sort of musing on it for a few seconds in a ‘think about how different our world would be’ type of way. He got about as far as realizing most of the Earth’s water would have frozen once and never really thawed. In summer it would get a layer of water on top a few inches or feet deep which would insulate everything below it and the rest would remain ice pretty much forever. Then he had sort of a mind blown moment and got back on with the lesson instead of going off on a tangent for the rest of the class.
It seems correct, I have no idea of it actually is or not. Like I said, he just sort of thinking outloud for a few seconds.
I was thinking that there might be a constant fog instead of actual rain with all the ice.
Joey P, I suspect your teacher was just pretending to have that sudden realization, since it’s a very well known result that he must have heard previously.
Yeah, it’s a standard pedagogical technique to walk through something like that step by step rather than just jumping straight to the conclusion.
Yes, it’s very possible. It may have been the hundredth time he walked through those exact same thoughts and then abandoned them to get back to the lesson. For all I know he did it an hour earlier with the class right before mine.
Of course it’s one of the famous ‘weird’ properties of water that is sort of important for supporting life in the goldilocks zone.
But what’s happening on places like Titan - where there are liquid hydrocarbon lakes? - are any of the solids there just the solid phase of those liquid hydrocarbons?
Also, is the Earth’s crust floating on the mantle? Does that mean rocks generally have a similar property to water in this regard?
Finally, if ice sank, the ending of *GI Joe - The Rise Of Cobra* would make a lick more sense
Earth is not a planet made primarily of water. In reality, there is only a tiny amount of water, relative to the mass of the earth. That is a key reason that the floaty ice thing matters.
The Earth’s crust has a different relationship to the interior than water does to the lithosphere. The interior is liquid because it has a lot of interior heat that mostly stays down there. Imagine a lava finger, where it solidifies in a crust on top but stays liquid inside until it finally cools and solidifies. That is essentially why the Earth is hard on the outside but runny on the inside. The crust is not really floating, as such, it just has nowhere to sink to (also, the mineral composition of the Earth is slightly less homogenous than water, so the crust will be mostly the lighter stuff).
The interior will probably eventually burn its last isotopes and stop making heat, but it will still take a few days to cool to a solid, by which time it will probably already be inside the photosphere of the dying sun. So get your affairs in order, the end is near – if you plan on living a few billion years longer or are not careful where you set that TARDIS down.
Yes, kind of
No. The rocks that make up the mantle are a different, denser composition from the rocks that make up the crust. To the best of my knowledge, all minerals (other than ice, which technically is a mineral) contract as they cool, so don’t exhibit the same property.
Almost irrelevant to this discussion, but not all ice is less dense than water. Ice that forms under very high pressures is denser than water; there is almost certainly a class of planets that has a thick layer of warm, high-pressure ice underneath water oceans a hundred kilometres deep. We just haven’t found any yet (AFAIK).
The presence of deep ice doesn’t necessarily preclude water on the surface.
OK, let’s be more rigorous and specify that we mean Ice I[sub]h[/sub]
Ice made of heavy water sinks, too. Of course, deuterium oxide is too rare in nature to make up even cubes of ice:
I think that might be the largest usage of ‘few’ I’ve seen.
Though this property is rare, it’s not completely unique to water. Antimony also shows the same effect, which is why it’s used in type metal (the alloy used to make type for printing presses): You want type metal to have the same volume when solid and liquid, so you can cast fine details in it.
I’m assuming that was some kind of odd typo. If you’d said “a few million years” rather than “a few days”, it would still be a gross underestimate. Around 1900, Lord Kelvin estimated how long it would take the earth to cool down from initial state to its current partially molten state (assuming no radioactivity, since that phenomenon was unknown at the time), and got a result of 20 million years. To cool from its current state to a complete solid would take much longer.
Issac Asimov covered this a long time ago.
Of Course not. The costal and lower lands would be flooded, but not the higher lands.
I’m not seeing your reasoning there, Silver lining. Why would lowlands be flooded, and why would that result in life as we know it not existing?
I would think we would have more build up of ice at the poles resulting in lower seal levels.