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What made Earth a giant snowball 700M years ago? Scientists have an answer

sydney.edu.au

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Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#161

Post by todd8 »

simonh wrote: post #114
huytersd wrote: post #107

Earlier quoted context omitted.

Oh wow. Maybe that can be a new scale measure of technological capability based on how much of reality we can perfectly simulate.

If you think about it, a computer's not going to be able to perfectly simulate it's own physical operation, so the limit of a system's ability to simulate things is it's own complexity.

This isn’t obvious to me. It doesn’t have to simulate itself in real time. It may not be able to simulate itself simulating itself. There may be proof of this using a diagonalization proof.

Consider programs that are quines, programs are able to output the exact source code of the program. See [1].

And there are abstract computers that can produce any computable output. These are called Universal Turing Machines, see [2]. UTMs can be specified with a remarkably small number of internal states, see [3].

I’m not saying you are wrong, but computability is full of unintuitive results, and the answer may be more subtle than what is revealed by “just thinking about it”.

[1] https://en.m.wikipedia.org/wiki/Quine_(computing)

[2] https://en.m.wikipedia.org/wiki/Universal_Turing_machine

[3] https://en.m.wikipedia.org/wiki/Wolfram%27s_2-state_3-symbol...

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#162

Post by roskelld »

nullhole wrote: post #19
itronitron wrote: post #3

Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.

That'd make for a good story setup: aliens park a shadeship (c) at L1 and wait. They block out most but not all of the sun. After some time (months? years?), conditions on Earth become unbearable, so earthlings have to mount an attack. Kind of like the movie Sunshine, but with more believable physics. Edit: as a bonus, it could take place in ~50-100 years, when global warming has gotten worse. The aliens could disgui…

That sounds like a great idea for a sci-fi novel, but before I steal and write it I thought I'd ask ChatGPT if it already exists, and it seems it does.

"The Forge of God" by Greg Bear The Makers deploy a vast, self-replicating robotic spacecraft called the "Doomsday Rock" near Earth's sun. The purpose of this massive construct is to absorb energy from the sun, causing it to dim and ultimately leading to the freezing of Earth, thus rendering it uninhabitable.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#163

Post by lamontcg »

dr_dshiv wrote: post #151
digging wrote: post #118

Earlier quoted context omitted.

More likely that if it's even possible, the chance is near 100%. However, it actually doesn't matter in any way whatsoever.

Except that we are living in a simulation, then it is morally wrong to be boring

wat

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#164

Post by goodSteveramos »

mikhailfranco wrote: post #91
jimmySixDOF wrote: post #8

There is a fantastic BBC Horizons documentary from the 90s called Snowball Earth that was easy to find on YouTube the last time I looked, but just now I see a hot mess of search results and if it's still in there somewhere I can't find it. EDIT: found it on dailymotion and its a great story of how the radical theory was rejected then accepted. https://www.dailymotion.com/video/x7o0b66

Google is dead and frozen, a lifeless snowball planet of searchy permafrost. From Page Rank primacy to worthless enshittified commercial crap, all in a Silicon Valley heartbeat. As one tech commentator put it, very politely, to a GOOG exec in a podcast: I used to find Google fantastic for answering my questions, but now it is only good for finding things to buy, not for finding out what I don't know. Someone please p…

Brave Search is just as good as DDG in my opinion.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#165

Post by Intralexical »

digging wrote: post #120
nullhole wrote: post #19

Earlier quoted context omitted.

That'd make for a good story setup: aliens park a shadeship (c) at L1 and wait. They block out most but not all of the sun. After some time (months? years?), conditions on Earth become unbearable, so earthlings have to mount an attack. Kind of like the movie Sunshine, but with more believable physics. Edit: as a bonus, it could take place in ~50-100 years, when global warming has gotten worse. The aliens could disgui…

> Warnings from a lone scientist would be ignored. A good movie plot, but I imagine in reality it would be obvious from the start that this would be a possibility and no scientists would be caught off-guard when the shade just didn't get removed. I can be almost certain as well that large factions of humans would "know" (believe, based on no facts) that is was happening all along and there would be incredible conflic…

> even before it was certain that is was an attack.

If it was done without consent, then it is an attack, and it doesn't fu*cking matter whether it ends up causing physical harm (or even if the invaders genuinely thought they meant well).

Regardless of whether it ends up taking away somebody's sunlight forever, it's still robbing people of all their agency. That decision was never theirs to make.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#166

Post by philipkglass »

apothegm wrote: post #143
philipkglass wrote: post #129

Earlier quoted context omitted.

It's the carbonate-silicate cycle. Erosion of silicate rocks (which form most of the Earth's crust) by chemical weathering consumes CO2 from the atmosphere and turns it into thermodynamically stable carbonates. Those carbonates can eventually be subducted and their CO2 released again by heat from the Earth's interior. https://personal.ems.psu.edu/~jfk4/PersonalPage/ResInt2.htm The carbonate-silicate cycle, which play…

So this basically also depends on a thriving population of shellfish to fix the carbon?

Calcium carbonate can also spontaneously precipitate out of solution, but it takes greater extremes of temperature, concentration, or other chemical changes. Shellfish increase the rate at which dissolved calcium carbonate converts to solid calcium carbonate. That action increases the rate at which trapped carbon can be returned to the atmosphere via subduction and volcanic emissions, which means a higher equilibrium concentration of atmospheric CO2 and a warmer planet than we would have if the oceans were lifeless.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#167

Post by Intralexical »

randomname93857 wrote: post #159
MR4D wrote: post #60

Earlier quoted context omitted.

I wonder how that would look from a feasibility perspective... Let's see - Earth's radius is 6,378 km. Area exposed to the sun therefore would be 6,378 * 6,378 * 3.14 = 127,731,695 [1] If you wanted to block just 1% of the light, that would take a shade of 1 million square kilometers, which would be equivalent to a shade that is 1,130 km on a side. Seems like it would be tough to do given all the dust and rocks float…

To provide full Sun shade, the shield should be at L1. and it should have the same angular size from Earth as the angular size of the Sun

> and it should have the same angular size from Earth as the angular size of the Sun.

Technically you need a bit more than that, for its umbra to block out the entire photosphere over the entire Earth:

https://en.wikipedia.org/wiki/Tangent_lines_to_circles#Outer...

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#169

Post by apothegm »

philipkglass wrote: post #166
apothegm wrote: post #143

Earlier quoted context omitted.

So this basically also depends on a thriving population of shellfish to fix the carbon?

Calcium carbonate can also spontaneously precipitate out of solution, but it takes greater extremes of temperature, concentration, or other chemical changes. Shellfish increase the rate at which dissolved calcium carbonate converts to solid calcium carbonate. That action increases the rate at which trapped carbon can be returned to the atmosphere via subduction and volcanic emissions, which means a higher equilibrium…

Thank you for the explanations!

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#170

Post by vmfunction »

yusml wrote: post #16
vmfunction wrote: post #7

Earlier quoted context omitted.

Better than nuclear weapon, no nasty fall out. Better than death star, you still have a planet afterwards.

If they had made the death star bigger, they could have done this tbh.

Too expensive!! Stratospheric aerosol injection are way cheaper!

https://en.wikipedia.org/wiki/Stratospheric_aerosol_injectio...

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