108 MARCH2020|COMPUTERSHOPPER|ISSUE385
tosolvethe Travelling Salesman
problem, which is notoriously difficult
forconventional computers, and while
the answer might have been computed
quickly,the whole process of preparing
the chemicals, bringing about the
chemical reactions, and reading out
the result took severaldays.
Things haven’t stood still, as recent
work on non-deterministic computers
at the University of Manchester
illustrates. Aclassic example of how
this works is solving amaze.Each time
ajunction is reached, rather than
following one of the two paths at a
time,asaconventional program would,
the code specifies that either path
could be taken, and the inherently
parallel nature of architecture allows
both to be taken simultaneously,using
DNA’s ability to replicate.
Biological
Given that computers are much
faster than the human brain forso
many problems, it seems reasonable
to assume that electronics is superior
to biology.However,thishasn’t
stopped researchers from
investigating the potential of
biological material forcomputation.
What’s more,even material from
primitive organisms is capable of
simple arithmetic calculations.
Forexample,scientists have used
neurons taken from aleech to
implement what theycalled a
‘wetware computer’. It was able to
add together two numbers and, while
this might seem trivial, it’s awhole lot
more than aleech can do.
Stranger still is computing with
slime mould. According to the Oxford
Dictionary,thisis“asimple organism
that consists of an acellular mass of
creeping gelatinous protoplasm
containing nuclei, or amassof
amoeboid cells”.Not apromising start,
you might think, but you’d be wrong.
Recently,researchers at the University
of the West of England in Bristol
demonstrated logic gates built from
slime mould, therebysuggesting the
possibility of universal computing.
Alternatively,the same researchers
have investigated the inherent
capabilities of slime mould to solve
certain very specific problems. Slime
moulds form anetwork of tubes to
move toward afood source along the
shortest path. In being able to find
the shortest paths, therefore –a
challenging problem in conventional
computing –scientists believe that
slime mould holds promise for
applications in communication
networks, robot path planning, and
much more besides.
The expertview
Painting abroad picture of the diversity
of alternative computing paradigms is
relatively straightforward, but coming
to aview on which might replace or
augment computers as we know them
is another matter entirely.Wespoke to
Bruce MacLennan, associateprofessor
of Computer Science at the University
Computing withcogs andgears
Mechanicalcomputersmightbeablastfromthepast,
butthatdoesn’tmeantheyhavenoplaceinthefuture.
Themostfamousmechanicalcomputer,ofcourse,is
CharlesBabbage’sAnalyticalEngine.Firstdescribedin
1837,andneveractuallycompleted,thisremarkable
contraptionhassincebeenrecognisedasembodying
manyoftheconceptsintoday’scomputers,eventhough
itwasbuiltofcogsandleversinsteadofelectronic
circuits.Needlessto say, itwouldhavebeenimmeasurablyslower
thanelectroniccomputers.
Now,however,scientistsattheUniversityofCaliforniaLos
AngelesandtheLawrenceLivermoreNationalLaboratory(LLNL)
havecreatedaMicroelectromechanicalSystems(MEMS)
computer,whichisbasedonlogicgates,muchliketheprocessorin
yourPC.Theprocessormightonlybeclockedatafew
megahertz,comparedto afewgigahertzforelectronic
devices,butit’snotbeingpositionedasasolutionfor
general-purposecomputing.Instead,it’ssuggested,
thesedevicesareideallysuitedto creating‘sentient’
materialsthatcanrespondto changesintheir
surroundings,eveninextremeenvironments.
Accordingto anLLNLspokesperson,thisapproach
“couldproveusefulinroverssentto hostileenvironmentssuchas
Venus,orinlow-powercomputersintendedto survivenuclearor
electromagneticpulseblaststhatwoulddestroyelectronicdevices.
InaVenusianrover,scientistscouldimplementacontrolsystemso
iftherovergottoohot,thematerialcouldopenitsporesto allow
inmorecoolant,withnoelectricityneeded.”
ABOVE:The two-
century old idea of
mechanical computing
–aspostulated by
Charles Babbage –
might just impact the
21st century,thanks to
MEMS techniques
