Knowing Very Little

Dr Rachel Oliver

17th November, 2013

•Knowing very little

•Chaplain suggested title

•Apt because

–I work on very little (small) things (nanotechnology)

–I often feel I know very little about those little things

–I know even less about speaking in chapel

•Hence – forgive my incompentence!

•What do I actually do?

•LEDs for lighting

•Tungsten filament bulb – 5% efficiency

•Light emitting diodes 5 to 10 times better

•20% of electricity generated in UK is used for lighting

•Changing to LED light bulbs would allow us to shut 5 – 10 medium sized power stations.

•? LED toys / hand-cranked generator here?

•Why are LEDs so efficient?

•Tungsten filament light bulbs – basically make heat

–Light as a bi-product – incandescence

–Useful in cold countries if buildings are well-insulated?

–Not so great otherwise…

•LEDs generate light directly

–Semiconductor materials

–Recombination of positive and negative current carriers

–No need for heat – although there is likely to be some due to imperfections in the material and limitations of device design

•Where do the very small things come in?

•“Active region” of LED

–Bit that the light actually comes from

–Made up of flat layers which are a few nm thick

–Structure in the plane of the layer is also very important to light generation mechanism

•Not going to go into detail….  But… 

–Light generation mechanism in blue (and white) LEDs not well understood

–Technology outstrips science

–We really do “know very little”

•If we know very little – how do we learn more?

•In my case, often by using microscopes

–Not familiar light microscopes (?magnifying glasses)

–Either electron microscopes or scanning probe microscopes

•Electron microscopes – a lot like light microscopes, but use a beam of electrons instead of light, and electromagnets as lenses

•Scanning probe microscopes – briefly describe AF using record player analogy

•Both offer atomic resolution – allow us to learn in detail about material structure and to relate this to device properties

•“Seeing” atoms

•Not  really seeing (!)

•Almost routine in some of the nanotech projects I have worked on

•Should be amazing!

•Scientists (?all of us?) need to make sure we don’t lose our sense of wonder.

•Huge privilege to have the opportunity to learn about the world in such detail.

•Seeing atoms – but knowing very little…

•Despite amazing microscopes and experiments – still don’t understand the basics of our device.

•Compare to Higgs Boson 

–Sometimes called the “God particle”

–“explains why other particles have mass, why things hold together, why you and I are able to exist”

–Good proof of it’s existence from LHC – some physicists now think that we completely understand the Unviverse.

•Aside – “God particle”

•Name invented by Leon Lederman

–(who won the Nobel Prize for Physics in 1988 for contributions in particle physics)

–Name for a pop science book in which Lederman wrote:  “Why God Particle? Two reasons. One, the publisher wouldn’t let us call it the Goddamn Particle, given its villainous nature and the expense it is causing. And two, there is a connection, of sorts, to another book, a much older one. . . .”  The Higgs is a concept of almost Biblical proportions.”

•Back to physics and thinking we know everything

•I trained as an engineer – not a physicist

•Doing my degree, my friends in physics were studying the “Grand Unified Theory of Matter” which purported to explain nearly everything…

•And I was learning that if you stick a heavy weight on the end of a thick wooden beam, it’s very difficult to say exactly how much it will bend

–Factor of two safety margin needed for building projects

•So we can explain nearly everything – but can’t figure out the simplest things?

 

•Knowing nearly everything?

•At the end of the 19th century many scientists believed they had discovered everything there was to discover and all universal phenomena could by explained through one of the three branches of the sciences: classical mechanics, electromagnetism and thermodynamics.

•In the early 20th century…

–Einstein’s theory of relativity, development of quantum mechanics

–Completely new picture of the universe

•I suspect we still know very little!

 

Summing up…

•Perhaps realising that we “know very little” is a good starting point for all scientists

•If I had two pieces of advice to give to someone starting out in science it would be to remember that – and to never lose sense of wonder.

•Lastly – even if we know more than we realise, all we really have is a set of laws for the Universe.

–Newton’s laws, laws of quantum mechanics…

–They work in their correct sphere, but where did they come from…?

•God as lawgiver?

•Isaiah 33:22For the Lord is our judge, the Lord is our lawgiver, the Lord is our king; it is he who will save us.

•I know that this actually refers to the 10 Commandments given on Mount Sinai and the rest of the Jewish Law (Torah)…

•However, part of my concept of God (to the extent that I have one) is as the giver of the laws of physics that control the Universe…  a different sort of lawgiver?

•Leave that as final thought….