Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

sydney.edu.au

Post reply on HN
Print view View original

91–100 of 193 posts

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

#91

Post by mikhailfranco »

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 put us out of our misery, and put Google down.

P.S. As a small start, Brave+DDG is infinitely better than Chrome+Google.

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

#92

Post by chefandy »

t00 wrote: post #85

From what I could gather from the paper, low CO2 leads to a potential ice age. Why the worldwide rush to reduce CO2 then?

> potential ice age > Why the worldwide rush to reduce CO2 then?

Illustrated answer:

https://xkcd.com/1732/

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

#93

Post by danielodievich »

Loughla wrote: post #44
Jenkins2000 wrote: post #38

Earlier quoted context omitted.

I really liked Pandora's Star (The Commonwealth Saga) by Peter F. Hamilton.

Currently reading that. And I am trying like hell to figure out how all of the different stories will come back together.

Oh you are in for a treat. They don't fully finish in that book, for the conclusion you need high-octane Judas Unchained with the best inter- and then planetary chase scene. A great book with lovely twist in the end.

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

#95

Post by jandrese »

robinzfc wrote: post #90
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…

Or maybe they showed up 200 years ago and thought: this is a very nice planet, except it's a bit too cold. What can we (compel the natives to) do to make it some 6 degrees warmer on average so that it is perfect for us? And the rest is history.

This is kind of the plot of Pacific Rim. The aliens originally invaded in prehistoric times, but then the Earth cooled and they had to retreat to their dimension. Humans then warmed it back up so they could restart the Kaiju invasion plans.

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

#96

Post by js2 »

macintux wrote: post #87
JohnFen wrote: post #86

Earlier quoted context omitted.

> Growing up I honestly thought that planets evolved into a sort of natural stable state that I guess I assumed would last This seems to be another expression of the truth that "people tend to mistake the limits of their view for the limits of the world."

Rumsfeld’s unknown unknowns.

Rumsfeld is famous for the quip, but it's basically an expression of the first stage of the four stages of competence:

1. You don't know what you don't know.

2. You know what you don't know.

3. You know what you know.

4. You don't know what you know.

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

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

#97

Post by jandrese »

mberger wrote: post #81
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…

Interesting. That area would be roughly one million Sunjammers[1]. One Sunjammer is 1200 m^2 and wights 32 kg. To lift all this would be 32 million kg or 32000 tons. One Starship launch is designed for 250 metric tons when expendable so it would take 128 launches. Add in some fudge factor for orbital burns and I figure 150 launches would do it. Doesn't seem insurmountable. Edit: Seems I misread the Starship capacity.…

If you are clever with cabling through your shade and launch in the right orbit you can use the Earths magnetic field to keep the things oriented properly. Astronomers would hate you though.

I'd guess it would be far more efficient to launch more of these into regular orbit than trying to assemble them out in L1 and keep them from drifting off, even though you would need to launch at least twice as many for the same amount of coverage.

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

#98

Post by mberger »

jandrese wrote: post #97
mberger wrote: post #81

Earlier quoted context omitted.

Interesting. That area would be roughly one million Sunjammers[1]. One Sunjammer is 1200 m^2 and wights 32 kg. To lift all this would be 32 million kg or 32000 tons. One Starship launch is designed for 250 metric tons when expendable so it would take 128 launches. Add in some fudge factor for orbital burns and I figure 150 launches would do it. Doesn't seem insurmountable. Edit: Seems I misread the Starship capacity.…

If you are clever with cabling through your shade and launch in the right orbit you can use the Earths magnetic field to keep the things oriented properly. Astronomers would hate you though. I'd guess it would be far more efficient to launch more of these into regular orbit than trying to assemble them out in L1 and keep them from drifting off, even though you would need to launch at least twice as many for the same…

[dead]

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

#100

Post by WarOnPrivacy »

SketchySeaBeast wrote: post #34
WarOnPrivacy wrote: post #14

Earlier quoted context omitted.

> Have you done the calculation how much material is required for such an endeavor? It's a tiny fraction of what's required for a proper Dyson sphere. And we know civilizations can afford those because we can no longer see their stars. For anyone who's hung up on saving nickle, we could do a low budget Worldring² or even thriftier Shadow Squares®. ²Nivenlarry ®Larry Niven

> And we know civilizations can afford those because we can no longer see their stars. That's a giant claim you just made like it's fact.

> That's a giant claim you just made like it's fact.

You are correct. That is absolutely a thing I did.

Post reply on HN