Domesticated Bacteria
Lord Broers, the President of England's Royal Academy of Engineering, recently said, "Our experience with chemistry and physics teaches us that we do not have any idea how to make an autonomous self-replicating machine at any scale."
Broers didn't say that autonomous self-replicating machines are impossible. Still, this caused a bit of a stir over at Howard Lovy's Nanobot blog where K. Eric Drexler responded (in part):
It is a pity that Lord Broers has joined the parade of denialists who discuss distorted versions of obsolete scenarios to the exclusion of all research in the field since 1990.
This problem - self-replicating machines - is being approached from multiple directions. Adrian Bowyer is working on macro-scale self-replicating machines. Howard Lovy's blog points to a multitude of scientists working on nano-scale inorganic machines. And we've recently had some important news from microbiologists. A team led by Ron Weiss at Princeton University has demonstrated the ability to command bacteria to form complex shapes and even colors. This is done through DNA instructions.
Weiss and his colleagues engineer a special segment of DNA, the blueprints for any cell's operations. The segment is called a plasmid.
"You have a segment of DNA that dictates when proteins should be made and under what conditions," Weiss told LiveScience. The plasmid is inserted into a cell, and "the cell then executes the set of instructions."
These pictures show two of Weiss' bacterial formations - a bullseye and a heart. Weiss believes that this technology could be quickly adapted to detect bioterrorism chemicals. The bacteria could literally form a bullseye around an anthrax microbe.
Long-term applications are even more interesting. Weiss has also shown the feasibility of making bacteria act like networked computers.
The cells, for example, could be made to perform basic mathematical logic and produce crisp, reliable readouts that are more commonly associated with silicon chips than biological organisms...
The creation of patterns, such as the bull's-eye effect, is a key step in one of Weiss' eventual goals, which is to have the cells secrete materials that build physical devices such as antennas or transmitters in places that are hard for humans to reach. Programmed cells also could be used to control the repair or construction of tissues within the body, possibly guiding stem cells to the locations where they are needed for the growth of new nerve or bone cells in a process Weiss called "programmed tissue engineering."
Imagine biological cyborgs - people with networked cells traveling throughout the body with programmed instructions to fix problems. An external server that looks like a nicotine patch could control this activity.
It's true that we have much to learn about autonomous self-replicating machines. Engineered bacteria may dominate the early years of nanotech. There's a precedent: the horse was domesticated before we built a car.