If this is to be anywhere near practical, we would likely first need to tap into the ZPE, or some other (yet undiscovered) high density energy source,
which does not rely on matter to energy conversion. Then we'll need to learn to extract that energy quickly and efficiently, such that we could produce large (read
huge) energy quantities within reasonable time. We would also need to learn to build system which could handle such energy fluxes. After that, we'll need to find a way to use that energy to efficiently produce any atom we need. Chances are that by the time we learn to do all that, nanotechnology will be quite well established, so it could take over at that stage to arange the produced atoms as desired.
All of this involves at least some new physics (except nanotechnology, for which the physics exists today), and most of it invloves
a lot of new physics. We may learn those things eventually, but probably not any time soon.
We may partially ponder the atom production stage today, but (I think) only to a limited degree.
Mk said:
If there was like... an anti-entropy machine, natural or man-made (though man came from nature...). You light a match, and blow it out. Its pretty hard to put all the smoke back in, un-burn the match, put back all the particles that were blown out... yeah.
That is not necessary, unless you want to convert matter to energy and then back to matter, and get all your original matter back the way it was. If you allow for some mass to be lost, you can do this without any "anti-entropy" machine. But that would be rather pointless. Converting ZPE or a similar type of energy into matter (i.e. skipping the matter to energy stage) would be far more usefull. And you will in fact get plenty of by-products, but there's not much we can do about that.