“The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done.” –Richard Feynman, 1959

Atomic Perspectives What’s the difference between graphite, coal, diamond? What’s the difference between a diseased cell and a healthy one? An old one and a young one? What makes up an apple? A steak? A bicycle tire? –How is an apple “made” now? Could we co-opt this power to make and build and create at the molecular level?

Miniaturization Top Down approach –Silicon computer chips –Mini motors Bottom Up approach –No whittling –No waste –Built from individual atomic “bricks” - no seams necessary –Can build literally anything

The Little Nano-box The raw materials (atoms) necessary for nano- production are everywhere Put air and grass into the machine and out pops a steak Put dirt in and out pops a backpack or sunglasses or a diamond-encased iMac with all the books ever written in its memory Little machines would self-replicate and then perform any task to which they are programmed But many scientists have said that it’s not possible because of Quantum Physics...

Issue #1: The Uncertainty Principle What is it? –Matter does not actually have distinct boundaries, instead position is uncertain –E.g. of an “electron probability cloud” –The larger the piece of matter, the more certain the position Is it a problem for nanotechnology? –Atoms position is only about 10% uncertain

Issue #2: kT - Thermal Energy A brief history (from Ch. 1) –Brown and his observations and experiments –What really causes the motion of the pollen –Feynman’s analogy –No real-world examples for us - tough to visualize How it effects matter: reactions, H 2 O, DNA What it would be like to be at the level of an atom Why we are big Is it a problem for nanotechnology? –Stable structures currently found in nature at different temperatures (thermal energies)

Issue #3: Radiation and Collision Molecular machines don’t need to be dropped to break (they actually wouldn’t if they were…), they could break from UV radiation Is it a problem for nanotechnology? –Like mRNA, if you have 3x10 8 of the machines, and they can replicate more, what’s the big deal if some don’t work?

Existing Nano-Machines Yes. They’ve actually been around for 3.5 billion years... DNA and some RNA are already capable of self- replicating Enzymes already take things apart or put them together atom by atom, molecule by molecule or structure by structure –Restriction enzymes, ligases, metabolic enzymes… lipase, alcohol dehydrogenase, amylase, etc. Why not make them by design?

Manufactured Enzymes Manufactured Enzymes: Shape is all that matters, but it’s complex... E.g. enzyme that puts a phosphate group onto glucose Nanomachines Nanomachines: Made from wheels, gears, bearings, tubes, switches, etc. Doesn’t rely upon random motion of particles...

What’s been done so far... Gene machines - custom made DNA sequences Small scale writing - Tale of Two Cities first page –Encyclopedia Britannic On the head of a pin –Library of Congress In one cubic centimeter Manipulation of atoms with scanning electron microscope - electrical repulsion Parts of machines built: Tube, switch, bearing, lever, motor, planetary gear –If a car is any analogy...

Consequences of Nano Disease and Aging –Molecular machines could specifically target damaged cells or defective DNA sequences –Small enough that 1000 could span your smallest capillary –Aging is just caused by the accumulation of defects over time Hunger, Poverty Classism, Sexism, Racism?… –A fall back to pre-agricultural society