So spider silk is one of the strongest materials known.
And in fact its strength is about that or even larger than
the strength of steel. It's a fascinating biological material
to study because spider silk is a material that is
essentially 100 percent, almost 100 percent, composed
from proteins. And proteins typically are weak materials
but spider silk is a prototype material in nature that has
the strength of steel but it's made from these very simple
and actually weak building blocks. If we in engineering are
trying to make materials that are as strong as steel, we
typically use very strong chemical bonds, and that means
we typically need a lot of energy to form these bonds.
Now the spider does not do that. The spider eats protein,
digests the protein, and essentially uses a liquid solution
of that protein and spins a fiber; and that fiber is as strong
as steel. So spider silk is a system in which we can actually
make a material with exceptional strength but using only
weak bonds. And what that means is we don't need
high-temperature, high-energy processing to make the
materials. In the early days we'd use analogies to explain
how materials like silk become so strong. And it's really
not because the proteins are very strong but it's really
because of the way these proteins are connected and the
way they form patterns. And we realized that it also can
be applied to other things; and that includes language,
art, many different forms of art, and music. So we're trying
to see if there are unconventional approaches to designing
things. Just think about any kind of popular melody, it's
enough to have a few tones and you play them and you
realize it's that piece of music, but if you play individual
tones or just have the instrument it doesn't mean anything.
So it's really the combination and the control and structure
in space and time. Then we went in and said, alright now if
we can show this, we should also be able to create our
own music to reflect certain materials. Of course the
composer wouldn't know about proteins so we actually
told him about two building blocks, or two entities, 'A' and 'B'
and we described a sequence. We described what they do
to one another once you mix them. So we basically
informed him in a very abstract sense using this
mathematical model how these systems behave, and he
then took this information and made music. (Music playing)
(Music playing)
When we listen to the music we can actually recognize
differences. The music that sounds more harsh reflects
the protein that has more of the 'A' building block. The 'A'
building block is a building block that forms very strong
interactions with one another. The 'B's are weakly-
interacting and they actually don't like to form organized
structures. The 'B's like to form disorganized structures.
The sequence that has more 'B', some 'A' but more 'B',
is reflected in the music by something more gentle.
(Music playing)
You can see a smoother, more friendly, gentle musical
piece, and the resulting network that you see once to look
at the fiber structures in detail, that it's a very well
connected network. So you can see that the 'A's still make
connections and they form these cross-links between the
chains, however there is enough freedom for these chains
to actually connect to other protein chains and thereby
form a good fiber. By doing this experiment, by creating
the music, we now know that these features are the ones
that reflect a better fiber - a better silk fiber. What we can
then do is we can ask the composer to emphasize on these.
So can he now create a new piece of music with the same
basic building blocks but playing on these theme, and
essentially emphasizing the features that we now know
make a better fiber. And the question is, can he actually
come up with a design that we wouldn't come up with.