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Rejuvenating Sun

joyrex

shaven wookie
joyrex
Joined
Jul 17, 2003
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698
In his artice from last year Seth Shostak mentions about means to rejuvenate the Sun:
In a few billion years, the Sun will begin to die, swelling up like a puffer fish. An obvious counter-move by our descendants would be to simply decamp to a cooler neighborhood, either farther out in the solar system (think: engineered habitats), or to another star system altogether. Either would be a grandiose engineering project, but this event is in a future so remote that it would be silly to assume that neither could be done. And in any case, migration would probably be simpler than trying to "rejuvenate" the Sun by changing the conditions in its dying core (a fix occasionally suggested by those who consider the possibility that someday we will not only go to the stars, but interfere with their personal lives).
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What is he talking about? This is something I haven't heard before, although I'm familiar with the term terraforming, for example.
 
Ok, I thought that when a star, same class as our sun mind you, dies, then it's because it's slowly expanding/exploding due to a change in the composition of the core due to the "normal" burning (agreed, it's been a while since I last checked into these matters). Once it's finished expanding, and pushing out matter in the process, not to mention demolishing a rather large part of our solarsystem in the process, it starts to fall back into itself until it's a white dwarf.
I can't really see how a "rejuvenation" should work. Theoreticly speculating one would have to replace the composition in the interior of the core with a more normal, viable "fuel" or introduce a catalyst which would re-convert the chemical composition of the core.
This process would take longer and require more resources than simply migrating somewhere else. Granted it would save the billions whom do not get a spot on a ship out of Dodge, but still.
The Timeframe itself is staggering, but also the amount of the catalyst or new material, which would probably rival the amount of a planet, and a finding a way to inject the material into something which melts everything in a radious of several tens of thousands of km.....
I don't see it happening.

And yes, this is also the first time I hear of this.
 
From http://helios.gsfc.nasa.gov/ed-acecosmo.html

STELLAR EVOLUTION AND ACE
The currently accepted theory of stellar evolution involves the following sequence of events. After the Big Bang, gravitation pulled together clouds of gas and dust to create giant clusters of matter. Continued contraction of these clusters eventually increased their temperature due to the interaction of colliding particles and the pressures created by the large gravitational attraction. As the temperature approached 15 million degrees, the electrons in the atoms were ripped off to create a plasma. (A plasma is the state of matter present when some or all an element's electrons have been separated from their nuclei.) Continued contraction occurred until the particles in the plasma moved with such high velocities (and therefore high energies and temperatures) that they began to fuse. The energy that was released eventually reached the surface of the cluster of matter, was released into space, and stars were born! It is believed that this fusion process produces enough energy to generate an outward pressure in the stars that reaches equilibrium with the inward pull of gravity. Our Sun is currently at this stage in its evolution and is fusing hydrogen to create helium .

The nuclear fuel (of light elements) which feeds the fusion process eventually runs out, and the stars end the first chapter in their lives. When the fuel runs out, the outward force which balances the gravitational attraction decreases. At that time gravitational forces again pull the outer layers of the star together, and the same processes that started the fusion process early in the stars’ history begin again. This time the star expands even more than before, and it becomes a red giant. The star may expand to one hundred times its original equilibrium size. The amount of time between a star’s birth and its red giant stage is dependent upon the original mass of the star.

The next step also depends upon the original mass of the star.
The Sun-like stars (stars having a mass approximately one-half to about three and one-half times the mass of the Sun) eventually deplete their nuclear mass to about 20% of what they had at birth. At that time they shrink to a white dwarf. This occurs as the inward pull of gravity again wins out over the decreasing outward pressure from the fusion process. These stars eventually cool and become cold and dark. They are often called black dwarfs.
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So, I think the theory that Seth is countering suggests pumping the Sun full of light, fusionable elements prior to its initial collapse, and subsequent expansion into a red giant.
 
But the amount needed is something like twenty Jupiters. And what do you do with the stuff that is already there?

We've come a long way towards being able to see hurricanes before they hit land. But we can't control 'em, and even if we could, we have scant idea of the long-term consequences of such control.

If hurricane control were to begin to become a reality in my lifetime, I might concede that star-control might become a reality before humanity dies out. Otherwise, I consider it wildly speculative at best.
 
"In a few billion years.......our descendents....."

Umm! does anyone think we'll still be around in a few billion years?

I have this insurance policy you must have! You to can have full coverage for just a few dollars a month.....(break to old geezer holding lemonade to deliver testimonial).
 
DrMatt said:
But the amount needed is something like twenty Jupiters. And what do you do with the stuff that is already there?
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Pump it out, if necessary. Just think of it as an oil change for your car, only on a somewhat larger scale.


We've come a long way towards being able to see hurricanes before they hit land. But we can't control 'em, and even if we could, we have scant idea of the long-term consequences of such control.
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I'm not sure this is a good analogy.

We've actually got some fairly good theories about stellar evolution and what causes things to happen. At some level, it really is as simple as "running out of fuel." Pumping thousands of Jupiters' worth of hydrogen into the Sun (and pumping out thousands of Jupiters worth of heavier elements) would ensure a fairly steady fuel supply and keep the sun from going along to the next stage, at least in theory. It's an engineering problem, not a basic science problem.

We have no idea at all how to control weather patterns. There's at least one basic breakthrough that would need to be made before we could design a solution to steering hurricanes around, even with the rather relaxed standards of "design" I was using above.

It's like the difference between "exceeding the speed of sound" and "exceeding the speed of light." Engineers knew that exceeding the speed of sound was possible, they just didn't know how to do it. Engineers -- and physicists -- don't even know if exceeding the speed of light is possible....
 
Some sci-fi authors (Wolfe, Niven, Bear) have speculated about the prospect of solar engineering on a grand scale.
The idea of "rejuvenating" a dying Sun is touched on by Wolfe in his "torturer" novels, essentially moving gas-giants into the solar mass. Of course, the ability to move planets would seem to be required...
 
I'm sure the intelligent cockroaches, (no, I don't mean politicians), which will be the only form of life left in a few billion years, will figure out a solution.
 
That's funny - I just finished (5 min ago) reading Asimov's The Last Question which deals with just this problem. He brings up a good point, which is the problem of increasing entropy. Although entropy can decrease locally, the overall entropy of the universe must always increase. The problem of rejuvinating stars turns into the problem of reversing entropy on a grand scale.

The Sun should last another 5 billion years or so. Personally I don't think we'll be around to care at that point. I'd be surprised if we last another thousand, at the rate we're going. But the Sun is one of the longer-lasting, small stars, and when it goes, there's a good chance most of the other nearby stars will be doing the same thing (or be gone already), so picking up and moving next door might be more of a problem than anticipated.

It's a short story, well worth the read. The full text is in the link above.
 
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