About as
long as there has been intelligent human life (or maybe even longer when one
considers the possibilities of various other intelligent life forms), a set of
fundamental questions have been posed lacking full answers regarding our
existence. As described in my last post, the continuation from the principles
of physics to chemistry to biology has offered these questions regarding how
this process has come about in such an elegant manner: how could the Universe
have possibly gone from the excess of matter particles to atoms to molecules to
life forms? While we have not solved these puzzles yet, many steps have been made
in the direction of answers.
My current
research in Germany has opened my eyes to many interesting aspects in answering
such questions. I’m not here to propose a concrete answer, but rather to
facilitate a similar curiosity in how such seemingly complex systems could
arise from the simple building blocks. This concept is central to the work done
in nanotechnology, which is the field I am currently exploring here in Munich—a
field that offers various interesting applications within my academic realm of
biomedical engineering. I will begin with a bit about the fundamentals of my
research for those of you back home that would like to know what I’ve been
spending time doing here, and to set the stage for the concepts that relate
back to the most crucial questions of the Universe.
I am
currently involved in research with Dr. Lackinger in a Nanotechnology Lab concerned
primarily with the characteristics of 2-dimensional surface-supported
self-assembly of supramolecular aggregates at the solid-liquid interface, often
resulting in nanoporous, monolayer crystalline networks depending on various
environmental conditions (yes, I strung all that together just for fun). What
does this mean in non-scientific terms? We look at how molecules can form
certain patterned networks on top of a surface. And how do we see these
molecules? I, specifically, use an instrument called an STM (Scanning Tunneling
Microscope).
STM-imaging
is based on a principle of quantum physics called quantum tunneling, where a
particle—in this case, namely an electron—tunnels through a potential barrier
in a way that classical physics would not allow. I will use a typical example
for sake of convenience; in classical mechanics, a ball would not be able to
reach the top of a hill and get to the other side without the necessary amount
of energy, but the quantum tunneling effect describes the phenomenon in which a
particle at an energy below that of the barrier tunnels through to the other
side. In the case of the imaging system, we get our image because of electrons that
tunnel between the atoms of a conducting or semi-conducting surface and atoms at
the tip of a sharp metal probe about 1 nanometer from the surface—an electronic
circuit made possible by electron tunneling. We get a tunneling current by applying
a bias voltage to the tip, and since the probability of quantum tunneling decreases
exponentially with distance, we use piezocrystals to constantly reposition the tip such that a constant current is maintained; therefore, the
tip maps the electronic structure as it is scanned across the surface.
We use this
STM then to visualize how molecules may assemble themselves on a surface (I use
graphite surfaces). The interesting point I want to share with you, and the
point that brings us back to the original discussion, is that this process of
network assembly happens spontaneously. The blueprint for this structure is held
in the characteristics of the building blocks themselves. The rules of the
interactions decide how the structure will come together. In my research, these
interactions are largely governed by hydrogen bonding of the molecules’
functional groups and Van der Waals interactions with the surface, all subject to the minimization of Gibbs free energy. So, when the rules allow it, a more complex entity can
result from the building blocks.
What then distinguishes
formation of life from this process, or from the process of particles forming atoms
in the early Universe? One of the unique characteristic of life is the process
of reproduction, and some form of information-carrying needs to exist to
facilitate that reproduction. The world today holds many complex biological
beings that have DNA to carry information, but was this always the case for life
forms? At the moment, there are a multitude
of viable theories set to explain how the transition may have happened: some
say genes first, some say metabolism first, some even land somewhere in the
middle. It is evident though that information had to be held through
aperiodicity, such as in the order of DNA bases, to allow reproduction. The
idea that this information came about through simple interactions of building
blocks is just simply astonishing to me.
I won’t go
on to explain any of the theories of life’s origin, but I will leave you with
something to let stew in your mind: if complex beings like humans developed after
billions of years through interactions governed by the building blocks, what
kind of other life forms do you think exist? Did they develop just like us? Are
they based in DNA? Has any of our biological information escaped and become a
template for life somewhere else, or could that have been exactly how we came
about?
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| Pictured above is my cartoon rendering of graphene, a single layer of graphite. I really only included this because I made it, I'm pretty proud of how it turned out, and it'd make a good thumbnail when I post the link. |
