Still plenty of room at the bottom?

Following up on Plenty of Room at the Bottom - how did Feynman do?

As I pointed out in an earlier post, Feynman's quintessential article imagines what accomplishments of which very, very tiny technologies and machines might be capable.

To summarize the contents of the article, Feynman:

• Appeals to visual logic by calculating how little space printed materials really need to take up (he shows that one could write the entire contents of all the volumes of the Encyclopedia Britanica on the head of a pin)
• Imagines a way, based on technologies available in 1960, to write and copy "written" information at such a small scale
• Describes how, by taking advantage of all three spatial dimensions, all print copies of every written medium in 1960 could fit on a spec of dust.
• Points out a need for the development of a better electron microscope to take this information processing strategy from being a possibility to becoming a reality; he also talks about several earth-shattering consequences of an electron microscope able to map and manipulate individual atoms
• Discusses possibilities and advantages of miniaturizing the computer
• Imagines miniaturizing machines, such as cars and robotic hands, and thinks through the logistical limits of scale, such as the volume needed in the engine blocks for combustion to occur, or the limits of human dexterity.
• Calls for high-school contests which use such "miniaturization technology"

So how did Feynman do? Nearly 50 years later, what has become reality and what is still a beckoning call to the modern physicist? 

• Computers are VERY much miniaturized compared with what they were in 1959. The logic gates used in modern computers are, in fact, reaching the limits of size, going down to about the scale Feynman calls out as the size limit (100s of atoms). New strategies are emerging which will allow for further increases in computational power once the limits of conventional electronics are reached (more on that in an upcoming blog post)! 
• Information is stored in very tiny capsules. Just think, the computer or smart phone you're using to read this has the ability to store about as much information as five average sized libraries! All in the palm of your hand.
• Modern electron microscopes have aided in the understanding of biological processes, and was instrumental in DNA sequencing, essential in mapping the human genome
• There are communities supporting high school students who regularly use scanning electron microscopes to take images such as this (a moth's eye):

photo credit: http://remf.dartmouth.edu/images/insectPart3SEM/image/22noctuidae120.jpg

For all the remarkable predictions Feynman made, some of his dreams have yet to become reality. These include: 

• a high numeric aperture electron microscope, capable of repeatably and reliably manipulating individual atoms
• miniature robotic hands capable of manipulating at the nanoscale (although there are tools which can be used to physically scribe things at that scale, such as the atomic force microscope)

One of the most important aspects of the continued development of the field of nanotechnology is understanding how physics is different at that scale, and what effects that are imperceptible to us at the scales we deal with in our day-to-day lives affect the nanoscale miniatures we're making every day. Several of the upcoming blog posts will deal with some of these weird effects and how we can explain them. 

Detecting Gravity (2017 Nobel Prize Winning Research)

Gravity. The stuff that keeps you grounded. And the stuff (from extremely distant stars and galaxies) that ripples all of earth's atoms a tiny, tiny amount all the time. Can we detect those ripples?

For eons, we've speculated (at best) as to what gravity is, and where its physical basis comes from. Albert Einstein, who pioneered the theory of general relativity which described gravity as a fundamental consequence of mass, and can lead to the strange distortions in space and time, thought it would be impossible to directly measure gravitational waves on earth, unless there was a nearby cataclysmic event (such as a neighboring galaxy getting sucked in a black hole). Until just a couple years ago (2015), it was impossible to measure gravitational waves. That is, until over 1000 researchers from more than 86 institutions came together and established the Light Interferometer Gravitational-wave Observatory (or LIGO, for short). There, they experimentally detected gravitational waves for the first time. 

The team used lasers that they beamed into two different perpendicular directions, one went north and the other one west. The mirrors were carefully positioned so that they were EXACTLY the same distance from the source. The effect of the gravitational waves that were reaching earth caused the mirrors to expand in one direction, and contract in the other. This effect was so weak that the net change in location was less than 1/1000th of an atom! But the LIGO team had carefully, painstakingly, accounted for every possible source of experimental noise which would drown out such a vanishingly small signal. And in the end, they found it. Two identical experiments at different parts of the country observe consistent results and now we have a way to directly observe how gravity warps spacetime.

 

photo credit: https://www.ligo.caltech.edu/assets/ligo_default_social_image-fa8a65b147c61b5147e1d43f9e7afc98.jpg

 

Bending the laws of thermodynamics at the atomic scale

Laws of Thermodynamics? More like suggestions!

This news feature, posted on Nature's website recently, discusses how various forms energy (heat, electricity, magnetism and light particularly) behave differently at the atomic scale. The laws of thermodynamics might not be breakable, but they can be bent! The following quote from the news feature demonstrates an example of how the standard laws of thermodynamics may, under special conditions, break down at the atomic scale.

Experiments are starting to pin down that quantum–classical boundary. Last year, for example, Schaetz and his colleagues showed that, under certain conditions, strings of five or fewer magnesium ions in a crystal do not reach and remain in thermal equilibrium with their surroundings like larger systems do.

In their test, each ion started in a high-energy state and its spin oscillated between two states corresponding to the direction of its magnetism — 'up' and 'down'. Standard thermodynamics predicts that such spin oscillations should die down as the ions cool by interacting with the other atoms in the crystal around them, just as hot coffee cools when its molecules collide with molecules in the colder surrounding air.

Such collisions transfer energy from the coffee molecules to the air molecules. A similar cooling mechanism is at play in the crystal, where quantized vibrations in the lattice called phonons carry heat away from the oscillating spins. Schaetz and his colleagues found that their small ion systems did stop oscillating, suggesting that they had cooled. But after a few milliseconds, the ions began oscillating vigorously again. This resurgence has a quantum origin, says Schaetz. Rather than dissipating away entirely, the phonons rebounded at the edges of the crystal and returned, in phase, to their source ions, reinstating the original spin oscillations.

- Z. Merali

So what impact does this have on technological developments? It demonstrates some of the ways in which as we try to miniaturize computer components further and further, the systems tend to no longer behave as expected. Instead of the thermal energy dissipating and staying away (as your coffee would eventually reach room temperature), these effects mean that the heat may be trapped, and eventually cause burn-out of the electronic components. However, the effect may also be used to process quantum information at higher temperatures - a major present hurdle to the realization of practical quantum computers.

Having been a theoretical discussion piece for the better part of 30 years, quantum effects on the laws of thermodynamics have lacked from experimental results, demonstrating such effects. The news feature discussed here showcases some recent experimental results which do just that.  

Photo credit: https://www.nature.com/news/the-new-thermodynamics-how-quantum-physics-is-bending-the-rules-1.22937

Plenty of Room at the Bottom

Plenty of Room at the Bottom

Nobel prize winning physicist, Richard Feynman, wrote an article in 1959. The title of the article was "There is Plenty of Room at the Bottom.": a call to action to physicists of the day to embrace an experimental exploration of the physics of the very tiny. He imagined what advancements, achieved through nanotechnology, might be like in the year 2000. His description is very inspiring, and presents the case very well how nanoscience is an area with plenty of room to explore. The effects go far beyond what he describes, and the technological reaches seen today are astounding. I will follow up with specifics and compare what Feynman predicted with what has been achieved since this was penned back in '59. Enjoy reading! 

-AW

Photo credit: http://www.nanobusiness.org/images/nanobusiness-nanotechnology-as-science-feynman.jpg

Welcome to the Human Frontier!

Scientists: the modern-day explorers

Few things pique my curiosity more than the limit of human interaction with the universe. It stirs the same part of my soul as learning of the voyages of Marco Polo, Amerigo Vespucci, Magellan, Columbus, Lewis and Clark... Western explorers of uncharted reaches of the earth. 

Today, there are few places on the surface of earth which are uncharted, but above us and below us, and the realms around us which cannot be seen by unaided eyes remain a mystery. 

The explorers of bygone centuries planned their voyages, trained for years, assembled highly skilled teams of brave souls willing to leave the world they knew behind for good, not knowing what they were going to encounter. They brought along the best technology of the era to explore these mysterious lands. The first explorers recorded everything to the best of their ability, but inevitably, there were some mistakes and misinterpretations along the way. Later explorers corrected and refined these explorations until we had an accurate understanding of the "New World". This is the same as the scientific endeavors of today. We, the scientists, are the modern-day explorers. We, the engineers, are on the human frontier. We will go bravely wherever the data takes us, and we will boldly proclaim, to the best of our ability, an accurate and precise interpretation of the data, expecting and eagerly anticipating corrections to reports and deviations from our apparent course.

This blog is a space where I will periodically share inspirational advancements in humanity, in our understanding of the universe. Check back for new and interesting discoveries! 

Photo credit: http://eskify.com/wp-content/uploads/2016/08/explorers-of-the-new-world_00003-1080x675.jpg