Thesis-PDF - IAP/TU Wien
Thesis-PDF - IAP/TU Wien
Thesis-PDF - IAP/TU Wien
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theory (see e.g. [1]).<br />
Now I call our times exciting, because we can build upon this hard work that<br />
has already been done, providing the foundations for understanding how particles<br />
interact and what effects have to be taken into account for a particular problem.<br />
As soon as such a collection of physical laws is in place, statements of the kind "It<br />
should be possible to do this and that" can be made. Ideas of what is possible can<br />
be derived from what we know. A theoretical prediction in this sense is nothing else<br />
than a statement that it should be possible to do this and that (the experiment)<br />
and obtain a certain result. The reasoning has been done a priori, before we carry<br />
out the actual experiment, the real thing.<br />
This is not something new and I will cite here a statement that has been made<br />
quite some time ago (in 1959) by a well know physicist - Richard Feynman (1918-<br />
1988). He stated "..there exists no reason why we shouldn’t be able to write the<br />
entire Encyclopedia Britannica on the head of a pin.." ([2]), while he discussed the<br />
idea that the laws of physics do not oppose the intentional manipulation of single<br />
atoms, assembling them as one wishes. Back then however, there was no imaging<br />
method having atomic resolution, and even less a way to manipulate single atoms<br />
in a controlled way.<br />
Then, in 1981, with the invention of the Scanning Tunneling Microscope<br />
(STM) (see Chapter 3) it was for the first time possible to directly acquire images<br />
of solid surfaces with atomic resolution. Along with the STM came the possibility<br />
to move atoms across a surface one by one. Since then the science of the small<br />
has seen explosive growth - Nanotechnology. For phenomena at the nanoscale,<br />
the tiniest realm of nature, we can today rephrase those statements (with good<br />
chances to find answers) of what should be possible into "How can we build, what<br />
we think is possible?".<br />
This is an extraordinary position to be in - We now can try out what could<br />
only be hypothesized before. The past two and a half decades have extended the<br />
knowledge and techniques greatly and the range of what seems possible to do is<br />
almost frightening. A new scientific continent is waiting to be discovered, rich<br />
in concepts, applications and deep consequences that reach too far than can be<br />
predicted beyond the near future.<br />
1.2 Complexity<br />
As soon as real systems have to be investigated, understood and built, a new challenge<br />
arises. In order to apply ideas from physics to progressively larger and more<br />
complicated structures, the interactions between many elementary constituents<br />
9