Planets that live forever

[MirceaKitsune]

Although this is a sad reminder, Earth and life on it will not be around forever. The most obvious reason is that a few billion years from now, the sun will have consumed itself. Apart from its disappearance removing the planet's only source of light, and releasing it from its orbit into an endless travel through space, the explosion the sun will cause during its death will turn all planets in the solar system to a crisp. And even if the sun wasn't a problem, there's the Earth's molten core. Eventually that will cool off too... meaning the Earth's tectonics will stop entirely, as well as the magnetic field surrounding it and protecting the surface from lethal radiation. So yeah, Earth and life that won't eventually go beyond it have their days pretty much counted.

 

But I wonder: Is that the case for all and any galaxy, solar system and planet out there? Could there be planets that might theoretically live forever? By theoretically, I mean planets that shouldn't break down due to reasons internal to them or their solar system. In practice it's hard to imagine this happening, considering that any solar system would eventually face extrenal problems. Such as being hit by a black hole or supernova or something else that's lethal... while it's also not certain if and when the universe and time itself have an ending or reach a point where they disintegrate.

 

Still, there are a few things that make me hope solar systems that could live forever might exist. Like I said, problem #1 with ours is that the sun will eventually burn out. It runs out of fuel because its nuclear reaction works one way, fusing hydrogen into helium (I hope I'm not mistaken about that). But what if another sun worked both ways, and fused one element into another then that element back into the first (nuclear fussion plus nuclear fission)? If its gravity is strong enough to make sure not a single particle escapes, the process could go on forever! Now in regard to its planets... well, unless space dust or anything that has mass slows them down in their orbit, they should theoretically keep going forever... not slowing down nor drifting further or closer to the sun.

 

Otherwise, planets with a molten core like Earth will eventually have that core cool off... unless that core can replenish itself too although that's even harder to imagine. Still, the core cooling off shouldn't mean the planet dies, nor that all life on it disappears. Certainly it means that the climate and even orbit will radically change, but at the surface some things could still keep going as usual. If we're to get into the survival of life on such a planet however, there is one problem here: Could the absence of a magnetic feel keep the sun from ripping away the planet's atmosphere, oceans, and everything in gas and liquid form... so the planet will not have the same fate Mars did?

[Delta1212]

You may not realize that's what you're doing, but you're looking for a perpetual motion machine. Those are impossible. Everything breaks down eventually. Everything. Full stop.

 

Any system will tend toward equilibrium until it runs out of usable energy. You can prolong that process by adding energy to the system, but in the absence of an external source of energy, eventually there won't be enough left to keep things "running."

[MirceaKitsune]

You may not realize that's what you're doing, but you're looking for a perpetual motion machine. Those are impossible. Everything breaks down eventually. Everything. Full stop.

 

Any system will tend toward equilibrium until it runs out of usable energy. You can prolong that process by adding energy to the system, but in the absence of an external source of energy, eventually there won't be enough left to keep things "running."

 

I remember hearing the term of "perpetual motion", used to describe people striving to find infinite energy. And I did hear that this is almost never possible.

 

I have however heard about nuclear fusion + nuclear fission... which could be used together to convert the same material back and forth and gain energy. Of course, if something generates energy, it pays a "price" for it... so it too would probably not last forever, and the atoms involved break down somehow (radiation?)

 

Maybe a more correct question would be: For how long can a solar system last? What composition and structure would the sun and planets need to have in order to live the longest?

[Moontanman]

A planet around a dim red star, possibly in orbit of a gas giant around that star might be extraordinarily long lived, orbital resonances might keep the core molten long after the radioactive elements have decayed but while it might be 100,000,000,000 years it would not be forever...

Edited May 13, 2014 by Moontanman

[MirceaKitsune]

Nice! Still a nice thought even if it's not forever. Although trying to think of 100,000,000,000 years I lose any notion of time, as that's too long to even try comprehending... so in a sense it does feel like forever.

[Ophiolite]

Although this is a sad reminder, Earth and life on it will not be around forever. The most obvious reason is that a few billion years from now, the sun will have consumed itself. Apart from its disappearance removing the planet's only source of light, and releasing it from its orbit into an endless travel through space, the explosion the sun will cause during its death will turn all planets in the solar system to a crisp. And even if the sun wasn't a problem, there's the Earth's molten core. Eventually that will cool off too... meaning the Earth's tectonics will stop entirely, as well as the magnetic field surrounding it and protecting the surface from lethal radiation. So yeah, Earth and life that won't eventually go beyond it have their days pretty much counted.

Just a couple of technical points. The entire solar system will not be burned to a crisp. Early calculation thought that in the red giant phase the sun would expand to engulf the Earth, but it would leave the giant planets relatively unaffected. It is now thought that the Earth, although now bereft of life, would survive.

[Megidolaon]

Entropy is a **** =/

[Greg H.]

Time for me to break out this nugget again:

 

C.P. Snow on thermodynamics:

Zeroth: You must play the game.
First: You can't win.
Second: You can't break even.
Third: You can't quit the game.

[Airbrush]

Nice! Still a nice thought even if it's not forever. Although trying to think of 100,000,000,000 years I lose any notion of time, as that's too long to even try comprehending... so in a sense it does feel like forever.

 

That number is too small. Red dwarf stars can last for Trillions of years. Not forever, but a very long time.

[Airbrush]

Could it be possible for an advanced ET to intentionally eject their home planet away from their star and exist as a rogue planet and use nuclear fusion for power to stay warm in interstellar space? Maybe they could leave their galaxy and drift for Trillions of years between galaxies.

[Delta1212]

Could it be possible for an advanced ET to intentionally eject their home planet away from their star and exist as a rogue planet and use nuclear fusion for power to stay warm in interstellar space? Maybe they could leave their galaxy and drift for Trillions of years between galaxies.

Really, it'd be a lot easier and more practical to just launch a very large spaceship out into interstellar space. Even a hollowed out asteroid or something.

[Airbrush]

Really, it'd be a lot easier and more practical to just launch a very large spaceship out into interstellar space. Even a hollowed out asteroid or something.

 

If they could move massive objects, why not take the entire planet with? That would be a lot simpler and more practical. Survivors would live in central cities, scattered around the planet, each powered by one (or many) nuclear fusion reactors. For fuel all they need to do is chip off a piece of ice outside the door.

[Delta1212]

 

If they could move massive objects, why not take the entire planet with? That would be a lot simpler and more practical. Survivors would live in central cities, scattered around the planet, each powered by one (or many) nuclear fusion reactors. For fuel all they need to do is chip off a piece of ice outside the door.

Imagine you have a nice sized pool in the back yard. Now you take an empty gallon milk-carton, fill it with water from the pool, carry it around to the front and dump it out on the street. That doesn't seem like to much effort right?

 

Now imagine trying to empty the entire pool into the street by hand, just using that 1 gallon carton.

 

The difference between moving a fairly large asteroid and moving a planet is approximately the same as the difference between moving a gallon of water and a swimming pool of water.

 

And in the case of the planet, the vast majority of the mass you're moving is on the interior which is completely useless to you. If you hollow out an asteroid, you can make use of the whole thing so you aren't carrying around extra mass. Hauling a planet just means you have to work that much harder to carry around a completely unlivable landscape surrounding your artificial habitats instead of solely carting around the useful living space.

[Airbrush]

I agree that a hollowed-out asteroid would be the better option. How could technology move an entire planet without causing great damage to it?

 

However, suppose the ET is capable of what we think is impossible, their planet drifting away outside of any galaxy would be safe from all supernovae, black holes, asteroids, other stars, etc. It would be a totally isolated rogue planet with an entire planet of resources for a journey of Quadrillions of years.

[jeffellis]

Perhaps in the future we will create such a planet.

[Moontanman]

I agree that a hollowed-out asteroid would be the better option. How could technology move an entire planet without causing great damage to it?

 

However, suppose the ET is capable of what we think is impossible, their planet drifting away outside of any galaxy would be safe from all supernovae, black holes, asteroids, other stars, etc. It would be a totally isolated rogue planet with an entire planet of resources for a journey of Quadrillions of years.

 

 

Hollowed out asteroid? How quaintly iron age ! Carbon will the the building material of space colonies, spinning torus shaped like endless suspension bridges held together with cables made with carbon nano tubes, the torus it's self will be made of graphene metals will be out dated!