62nd Lindau
Nobel Laureates Meeting
Open to the
Unexpected
- Not
without resistance: the long journey from a laboratory note to the Nobel Prize
- How
important it is to trust one’s own experiments
- Shechtman:
“Experts recognise a discovery immediately”
Lindau, 6 June
2012. The persistence with which outstanding researchers defend their
interpretation
of measurement results against the prevailing opinion has often contributed to
scientific
progress. Dan Shechtman, 2011 Nobel Laureate in Chemistry, is a good example
here. He
defended his
discovery of quasi-periodic crystals for more than ten years before it was
recognised.
He, as well as
26 other Nobel Laureates and more than 580 young scientists from all over the
world will
participate in the 62nd Lindau Nobel Laureate Meeting, which will focus on
physics.
Two further
researchers who were awarded the Nobel Prizes because they consistently pursued
surprising
leads and thus discovered materials with new physical and chemical properties
are Sir
Harold Kroto
and Douglas Osheroff. They will also be present at this year’s Lindau Meeting,
which
takes place
from 1 to 6 July.
Perseverance
Pays
Dan Shechtman
needed a lot of stamina to fight for the recognition of his pioneering
discovery.
On the morning
of 8 April 1982, results of an electron diffraction he was using at Johns
Hopkins
University to
investigate a quickly solidifying aluminium-magnesium alloy showed him a
completely
unexpected image. Instead of a symmetric crystalline arrangement in three, four
or
six-fold axes,
the diffraction pattern indicated ten-fold axes – an arrangement where the
individual
atoms no longer had the same distance to all neighbours, which at the time was
considered to
be absolutely imperative for a crystal. Shechtman’s results revealed an
aperiodic
pattern,
similar to the medieval mosaics in the Alhambra Palace in Spain. Shechtman
noted down
the discovery
in his laboratory book with three question marks – but he believed in it, as he
now
remembers:
“Science is basically experimental and an expert quickly recognizes a discovery
when
he stumbles
upon one.” Further measurements confirmed Shechtman in his discovery, the then
unknown
quasi-periodic crystal form. However, there was a great host of critics, as the
quasicrystals
did not conform
to the school of thought at that time. Nevertheless, Shechtman was not
distracted, and
he and his colleagues tenaciously continued with their research at the Technion
in
Haifa. “An
expert always checks his own results. If his further experiments prove him
right, he
can stand tall
against all criticism that may come from theoreticians,” he says today.
Only when they
succeeded in producing larger quantities of quasi-crystals and confirming their
pattern by
X-ray diffraction were Dan Shechtman and his colleagues able to convince the
International
Union of Crystallography of the existence of quasi-crystals – ten years after
their
discovery. And
the definition of crystals was altered. Today, owing to their brittle and hard
properties, the
quasi-crystals are already being used in the production of particularly hard
steels,
for example.
Exotic
Superfluidity
Solids, liquids
and gases are the states of matter which we encounter every day. They are
linked
to physical
phenomena such as friction between adjacent particles. A vortex in a liquid
which
was generated
by stirring therefore stops again by itself. Physicists, however, know a
further
state of
matter: superfluidity. Superfluid liquids continue to flow without any friction
whatsoever.
This exotic state of matter is important for many physics-related research
fields –
from quantum
mechanics through to cosmology. Researchers had known since 1911 that helium 4
had such a
superfluid phase close to absolute zero. Helium 4 has an integral spin and is a
boson;
these are
particles that can collectively make the transition into a superfluid state in
accordance
with Bose-Einstein
theory. Helium 3 has half-integer spin and is thus a fermion, and differs
significantly
from helium 4 in its physical properties at low temperatures. According to the
Barden-Cooper-Schriefer
(BCS) theory for the explanation of superconductivity (Nobel Prize for
Physics 1972),
it was to be expected that helium 3 could also achieve the superfluid state
under
certain
conditions – the formation of a so-called Cooper Pair.
Doctoral
student Douglas Osheroff confirmed this through his presence of mind one night
in
April 1972. He
investigated the magnetic properties of solid helium 3 only 0.2 degrees above
absolute zero
at Cornell University in Ithaca. His aim was to record a so-called phase shift
by
increasing the
pressure as a function of time. However, he noticed unexpected jumps in the
measurement
curves. “The liquid NMR signal dropped by about a factor of two at the lower
temperature
transition. I felt that this had to be the result of the formation of ‘Cooper
Pairs’ in the
liquid,” he
remembers. Way after midnight he wrote in his notebook: “2:30 AM have
discovered
the superfluid
phase transition in liquid 3He tonight.” Several months of careful
measurements,
which Osheroff
carried out with his supervisor David Lee and his faculty colleague Robert
Richardson,
were required to confirm this discovery. In 1996, the trio was awarded the
Nobel Prize
for Physics for
this feat. In his talk, Osheroff will discuss his view of “How Advances in
Science are
Made” at the
62nd Lindau Nobel Laureate Meeting.
Fascinating
Carbon Spheres
“Always expect
the unexpected,” says Sir Harold Kroto, who, together with Robert Curl and
Richard
Smalley, was honoured with the Nobel Prize for Chemistry in 1996 for the
discovery of
the fullerene.
This carbon type, with molecules arranged like honeycombs that form a sphere,
was
a real
sensation, as it represents a completely new form of solid carbon. Until then,
the only solid
carbon lattices
known were hard diamond and soft graphite. The names of the carbon spheres
(buckyballs and
fullerenes) are reminiscent of the dome constructions of the architect
Buckminster
Fuller.
During a guest
stay at Rice University in Houston in the laboratories of Smalley and Curl,
Kroto
vaporised
graphite with a laser beam in a helium jet in order to detect short carbon
chains as they
would be
expected from measurements in interstellar space. However, a mass spectrometric
scan
showed the
largest peak at a compound which apparently consisted of 60 carbon atoms. Curl,
Kroto and
Smalley developed the idea of the sphere with 60 carbon atoms. “I had the
strong gut
feeling that it
was so beautiful a solution that it just had to be right,” remembers Harold
Kroto.
Like Shechtman,
he began to verify this assumption or “falsify it himself” in case of any
doubt.
Soon the
results were recognised and fullerenes became the sought-after research object.
They are
considered to
be potential catalysts and lubricants, as well as semiconductors and
superconductors.
Recently, fullerenes in the solid state, provided cause for excitement: They
were
detected with
the Spitzer infrared telescope in the vicinity of a pair of stars known as XX
Ophiuchi.
In his talk
“Lost in Translation” at the 62nd Lindau Nobel Laureate Meeting, Sir Harold
Kroto will
discuss the
necessity of communicating scientific language and content. Recognized as an
inspiring
science communicator, he has long been a champion of communicating science more
strongly via
the Internet with such projects as Vega and Geoset.
Communicating
scientific content and debates is also a crucial concern of the Lindau
Meetings.
Their online
platform is the Lindau Mediatheque. It comprises audio recordings and videos of
the
talks of Nobel
Laureates from the more than 60 years of history of the Lindau Meetings. With
supplementary
background information, photos, links to related contents and didactically
edited
“mini
lectures”, the Lindau Mediatheque is a unique resource for researchers, those
interested in
science,
journalists and teachers alike.
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