“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, H2O, 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 3x108 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: Shape is all that matters, but it’s complex...
Nanomachines: Made from wheels, gears, bearings, tubes, switches, etc.
E.g. enzyme that puts a phosphate group onto
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
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