I think the difference is that evolution has also created competitors, predators and built in limits to growth that keeps any particular life form from replicating out of control and destroying everything else. With the exception of humans perhaps :)
If the grey goo is non biological, there may not be any form of life that can eat it to keep its growth in check, it might also use some raw material that's more abundant than the nutrients organic life needs (there's a lot of silicon in earth's crust for instance), and it probably wouldn't have any built in limit to its replication like most living things do.
This has me wondering whether there are any chemical reactions that use rock or dirt and yield energy. If those don't exist, gray goo needs to get staggering amounts of energy from somewhere before it can be dangerous. But if they do, why isn't anything biological using them?
"Rare, chemolithoautotrophic bacteria are believed to
occur in the cave. These bacteria feed on the sulfur,
iron, and manganese minerals and may assist in enlarging
the cave and determining the shapes of some unusual
speleothems. Other studies indicate that some microbes
may have medicinal qualities that are beneficial to
humans.[1]"
The idea, I think, isn't that this grey goo would get energy from dirt and rock and literally consume the Earth. Rather, it would use dirt and rock plus solar energy to grow and if its efficient enough out compete existing plants. The other bad possibility is that some nanite comes along that can digest typical organic matter but that can't be digested in turn. Then it proceeds to much on the biosphere while leaving the rest of the planet alone and just eat all the organic life (that hasn't hermetically sealed itself away).
Either of these scenarios would, of course, be Bad Things.
I'm not sure either is actually credible, but I'm not aware of any reason to declare them impossible.
Comments
I think the difference is that evolution has also created competitors, predators and built in limits to growth that keeps any particular life form from replicating out of control and destroying everything else. With the exception of humans perhaps :)
If the grey goo is non biological, there may not be any form of life that can eat it to keep its growth in check, it might also use some raw material that's more abundant than the nutrients organic life needs (there's a lot of silicon in earth's crust for instance), and it probably wouldn't have any built in limit to its replication like most living things do.
This has me wondering whether there are any chemical reactions that use rock or dirt and yield energy. If those don't exist, gray goo needs to get staggering amounts of energy from somewhere before it can be dangerous. But if they do, why isn't anything biological using them?
There are bacteria in a certain cave system that draws energy from the mineral deposits. They get 0 energy from the sun.
A little searching found: http://newsinfo.iu.edu/news/page/normal/4229.html
I don't think that this is the bacteria that I was thinking of. The one the I'm thinking of was mentioned in the Planet Earth episode on caves.
{EDIT}
http://dsc.discovery.com/news/2009/05/08/cave-bacteria-mars....
http://en.wikipedia.org/wiki/Lechuguilla_Cave
{/EDIT}The idea, I think, isn't that this grey goo would get energy from dirt and rock and literally consume the Earth. Rather, it would use dirt and rock plus solar energy to grow and if its efficient enough out compete existing plants. The other bad possibility is that some nanite comes along that can digest typical organic matter but that can't be digested in turn. Then it proceeds to much on the biosphere while leaving the rest of the planet alone and just eat all the organic life (that hasn't hermetically sealed itself away).
Either of these scenarios would, of course, be Bad Things.
I'm not sure either is actually credible, but I'm not aware of any reason to declare them impossible.