Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Footkerchief]

You can get away without using the sun as a energy source, it's just much tougher. You've got geothermal and sulfur reactoions for example.

Those won't last forever, as I've been trying to say.  If they did, thermodynamics would be broken.

The term "forever" is a bit specious in this context.  Plus, radioactive decay etc. would continue on earth even in the dark.

[LegoLord]

But radioactive decay would eventually stop as well, as the radioactive material would eventually run out.

[Footkerchief]

But radioactive decay would eventually stop as well, as the radioactive material would eventually run out.

Likewise the sun will fizzle out.  In a similar timeframe, even (U-238 has a half-life fairly close to the sun's life expectancy).  I don't get your point.

[LegoLord]

Underground settlements can't last as long without the sun as they can with some indirect link to the sun.

[Kardos]

Underground settlements can't last as long without the sun as they can with some indirect link to the sun.

Yes Yes, so as apposed to ten billion years of life under the sun, we have 5 billion years of life under the crust.  Add to that the the planet itself would still be hit by the suns rays, its thermodynamic power will remain fairly constant.  Add to that radioactive elements which release energy, and can take over billions of years to effectively decay (given enough mass), the argument that life can't exist without direct support from the sun is fairly photosynthetic centric.

[LegoLord]

You do realize that the core is (slowly) cooling, right?  Radioactivity . . . that's not available in every underground area, and when we use it for reactors (which we probably would), the energy gets used up faster.  The main problem is that underground energy sources aren't renewable, whereas with the sun there's probably some way to control how long it lasts, granted we're a long way off from that.  You don't have to keep moving your home around when you have some indirect link to the sun (a river that passes both above and below ground before reaching you, for example).

[Mel_Vixen]

Well everything deeper then 300 Meters (as isolatig outer layer) will survive. Bacterias, fungy etc are going deep underground cause the core is hot enought to heat the crust by 3 Degree per hundret meters you go down. As long there is water it works.

And the heat is "renewable" cause the fission down there and the pressure will work for milliards of years.

[Footkerchief]

You do realize that the core is (slowly) cooling, right?  Radioactivity . . . that's not available in every underground area, and when we use it for reactors (which we probably would), the energy gets used up faster. 

Radioactivity is "not available in every underground area"?  We aren't talking about freezing humans huddling around a pile of uranium pellets, we're talking about radioactive decay keeping the mantle warm enough that hydrothermal vents remain active, giving chemoautotrophs their source of energy.  For these purposes the mantle is uniform, and humans will never extract a significant amount of uranium or any other nuclear fuel from the mantle.  It's far more economical to extract uranium from seawater anyway, and that source is practically unlimited.

The main problem is that underground energy sources aren't renewable, whereas with the sun there's probably some way to control how long it lasts, granted we're a long way off from that. 

You think it would be easier to stabilize the sun than to just find some uranium-rich asteroids or even siphon hydrogen from a gas giant?  Really?  The sun is not inherently more infinite than other sources of energy.  A star is just a fusion reactor, it uses fuel like anything else.

[LegoLord]

siphon hydrogen from a gas giant?  [. . .]  A star is just a fusion reactor, it uses fuel like anything else.

Hydrogen is the primary fuel component in fusion reactors.  And on a gas giant, it probably wouldn't be pure hydrogen form, but that would probably be good enough for a star so hot simple particles can't hold together.  The other thing about the sun is that it can use some other gases slightly larger than hydrogen; that's how we get all the large elements like gold, iron, and lead.

[Mel_Vixen]

Hey do it the dwarfen way. Get a huge torch and make Jupiter and saturn stars .

[Footkerchief]

Hydrogen is the primary fuel component in fusion reactors.  And on a gas giant, it probably wouldn't be pure hydrogen form, but that would probably be good enough for a star so hot simple particles can't hold together.  The other thing about the sun is that it can use some other gases slightly larger than hydrogen; that's how we get all the large elements like gold, iron, and lead.

Jupiter is only .001 solar mass.  It would be a drop in the bucket, and if you were that desperate for energy it would be wasteful to throw all your fuel into the sun (which will radiate 99.99999% of the energy into space) rather than using it in artificial reactors.

[Muno syoan]

Interestin' point; I read a journal last year that had the exact energy consumption specifics of obtaining useful organic compounds from melanin and radiation, and it turns out that with a sufficently slow and specialised metabolism, you can keep some species fungi alive indefinateley on the equivalent of cosmic radiation.  Admitidely, cosmic radiation levels fluctuate, but from a mean value enough melanin breaks down to keep the organism alive.
So bugger the sun. All you need is some type of energy source and an atmosphere (not necessarily a human breathable one) and you've got fungal (and symbiotic/parasitic prokaryotic/ viral) life, no matter how sparse. (The earths' magnetic field would be not only unnecessary but potentially detrimental, for obvious reasons.)

I'll see if I can dig out the journal in question, I believe I made notes.

TL;DR: Life can be really cheap to fuel if it's done under the right conditions because life likes living, and has had a lot of practice at it.

[PMantix]

The human (or dwarven..) race has a lot of other problems to worry about before seriously thinking about what to do when the sun is spent..


..but anyway, here is a short story by Asimov on a similar topic you may find interesting. The Last Question By Isaac Asimov, 1956.


Reading the exchanges between Footkerchief and LegoLord above reminded me of the two drunken technicians at the beginning.

[LegoLord]

eading the exchanges between Footkerchief and LegoLord above reminded me of the two drunken technicians at the beginning.

No, No!  I shwear to shober I'm not Armok.

[PMantix]

eading the exchanges between Footkerchief and LegoLord above reminded me of the two drunken technicians at the beginning.

No, No!  I shwear to shober I'm not Armok.

The conversation was what I was referring to..   the drunkenness was purely speculation.