So, my name is Dan Shechtman.
I am a distinguished professor
at the Technion Institute in Isreal.
I’m a laureate of the Nobel Prize in Chemistry,
2011, for the discovery of quasi-periodic crystals.
Before that, the definition of a crystal was:
a crystal is a material in which atoms
are ordered and periodic. Period.
If you want to understand periodicity,
look at tiles on the floor.
If they are squares then in each and every direction
that you point you see that the tiles repeat themselves
in exactly the same way.
This is two-dimensional periodicity.
Quasi-periodicity is more complex.
It appears in nature in a more complex way,
such as spirals that we find in pine cones
and shells of certain sea life.
So, let’s talk about quasi-periodicity in two-dimensions,
and the perfect example of Penrose tiles.
You can tile a floor with Penrose tiles.
You can do it quasi-periodically
if you follow certain matching rules
and there will be no gaps and everything will fit properly.
So, two dimensional are Penrose;
three dimensional are quasi-periodic crystals.
So, the year was 1982 and after lunch I put aluminium –
twenty-five percent manganese – under the microscope
and I started to look at it.
When I first saw the diffraction pattern
with ten-fold rotation symmetry,
I looked at it and said in Hebrew: (speaks Hebrew).
It means, ‘No such animal’.
This discovery was a paradigm shift in crystallography.
It created a new definition of what a crystal is.
So, today we have many, many crystals
which have three-dimensional quasi-periodicity
– hundreds of them, in fact.
It is quite surprising
that they were not discovered before.
We all want to make sure that our food is safe
but doing that can be really hard.
Looking for contaminants in raw materials is tough.
The statistics are stacked against us.
Today, we can only test for pathogens individually:
one sample at a time.
And that means hundreds if not thousands of tests,
most of which deliver a simple negative result.
We needed to think about this differently.
That’s why Mars and IBM joined forces:
to sequence the genomes of all the organisms
in the food supply chain.
That’s millions of organisms.
But big data is what IBM is good at.
The DNA and RNA sequences
show you all the harmless bacteria
that are found in normal, safe food.
If we do the test
and the microorganisms are suddenly different,
something’s up.
The organisms have changed
because the environment has changed.
It could be contaminated.
And not only that, this tells us things
that we never could have seen before,
like where the food was grown,
how it was transported
and maybe even what happened en route.
Our approach to food safety just got a lot smarter.