Chemical computer
Encyclopedia
A chemical computer, also called reaction-diffusion computer, BZ computer (stands for Belousov–Zhabotinsky computer) or gooware computer is an unconventional computer
based on a semi-solid chemical "soup" where data is represented by varying concentrations of chemicals. The computations are performed by naturally occurring chemical reaction
s. So far it is still in a very early experimental stage, but may have great potential for the computer industry.
is an incredibly complicated device that can be destroyed during production
by no more than a single airborne microscopic particle. In contrast a cup of chemicals is a simple and stable component that is cheap to produce.
In a conventional microprocessor the bits behave much like cars in city traffic; they can only use certain roads, they have to slow down and wait for each other in crossing traffic, and only one driving field at once can be used. In a BZ solution the waves are moving in all thinkable directions in all dimensions, across, away and against each other. These properties might make a chemical computer able to handle billions of times more data than a traditional computer. An analogy would be the brain
; even if a microprocessor can transfer information much faster than a neuron
, the brain is still much more effective for some tasks because it can work with a much higher amount of data at the same time.
scientist, in the 1950s. He created a chemical reaction
between different salts and acids that swing back and forth between being yellow and clear because the concentration of the different components changes up and down in a cyclic way. At the time this was considered impossible because it seemed to go against the second law of thermodynamics
, which says that in a closed system the entropy
will only increase over time, causing the components in the mixture to distribute themselves till equilibrium is gained and making any changes in the concentration impossible. But modern theoretical analyses shows sufficiently complicated reactions can indeed comprise wave phenomena without breaking the laws of nature. (A convincing directly visible demonstration was achieved by Anatol Zhabotinsky
with the Belousov-Zhabotinsky reaction
showing spiraling colored waves.)
transmitting and changing ones and zeros through a complicated system of logic gate
s. To perform any conceivable computation it is sufficient to have NAND gates
. (A NAND gate has two bits input. Its output is 0 if both bits are 1, otherwise it's 1). In the chemical computer version logic gates are implemented by concentration waves blocking or amplifying each other in different ways.
. This led to an upsurge in the field of chemical computing. Andrew Adamatzky at the University of the West of England
has demonstrated simple logic gates using reaction-diffusion processes. Furthermore he has theoretically shown how a hypothetical "2+ medium" modelled as a cellular automaton
can perform computation.
The breakthrough came when he read a theoretical article of two scientists who illustrated how to make logic gates to a computer by using the balls on a billiard table
as an example. Like in the case with the AND-gate, two balls represents two different bits. If a single ball shoots towards a common colliding point, the bit is 1. If not, it is 0. A collision will only occur if both balls are sent toward the point, which then is registered in the same way as when two electronic 1's gives a new and single 1. In this way the balls work together like an AND-gate.
Adamatzkys' great achievement was to transfer this principle to the BZ-chemicale and replace the billiard balls with waves. If it occurs two waves in the solution, they will meet and create as a third wave which is registered as a 1. He has tested the theory in practice and has already documented that it works. For the moment he is cooperating with some other scientists in producing some thousand chemical versions of logic gates that is going to become a form of chemical pocket calculator.
One of the problems with the present version of this technology is the speed of the waves; they only spread at a rate of a few millimeters per minute. According to Adamatzky, this problem can be eliminated by placing the gates very close to each other, to make sure the signals are transferred quickly. Another possibility could be new chemical reactions where waves propagate much faster. If these teething problems are overcome, a chemical computer will offer clear advantages over an electronic computer.
An increasing number of individuals in the computer industry are starting to realise the potential of this technology. IBM
is at the moment testing out new ideas in the field of microprocessing with many similarities to the basic principles of a chemical computer.
Unconventional computing
Unconventional computing is computing by a wide range of new or unusual methods. It is also known as alternative computing. The different methods of unconventional computing include optical computing, quantum computing, chemical computing, natural computing, biologically-inspired computing, wetware...
based on a semi-solid chemical "soup" where data is represented by varying concentrations of chemicals. The computations are performed by naturally occurring chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
s. So far it is still in a very early experimental stage, but may have great potential for the computer industry.
Rationale
The simplicity of this technology is one of the main reasons why it in the future could turn into a serious competitor to machines based on conventional hardware. A modern microprocessorMicroprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
is an incredibly complicated device that can be destroyed during production
Semiconductor fabrication
Semiconductor device fabrication is the process used to create the integrated circuits that are present in everyday electrical and electronic devices. It is a multiple-step sequence of photolithographic and chemical processing steps during which electronic circuits are gradually created on a wafer...
by no more than a single airborne microscopic particle. In contrast a cup of chemicals is a simple and stable component that is cheap to produce.
In a conventional microprocessor the bits behave much like cars in city traffic; they can only use certain roads, they have to slow down and wait for each other in crossing traffic, and only one driving field at once can be used. In a BZ solution the waves are moving in all thinkable directions in all dimensions, across, away and against each other. These properties might make a chemical computer able to handle billions of times more data than a traditional computer. An analogy would be the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
; even if a microprocessor can transfer information much faster than a neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
, the brain is still much more effective for some tasks because it can work with a much higher amount of data at the same time.
Historical background
Originally chemical reactions were seen as a simple move towards a stable equilibrium which was not very promising for computation. This was changed by a discovery made by Boris Belousov, a SovietSoviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
scientist, in the 1950s. He created a chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
between different salts and acids that swing back and forth between being yellow and clear because the concentration of the different components changes up and down in a cyclic way. At the time this was considered impossible because it seemed to go against the second law of thermodynamics
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...
, which says that in a closed system the entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
will only increase over time, causing the components in the mixture to distribute themselves till equilibrium is gained and making any changes in the concentration impossible. But modern theoretical analyses shows sufficiently complicated reactions can indeed comprise wave phenomena without breaking the laws of nature. (A convincing directly visible demonstration was achieved by Anatol Zhabotinsky
Anatol Zhabotinsky
Anatoly Markovich Zhabotinsky created a theory of the Belousov-Zhabotinsky reaction in the 1960s and published a comprehensive body of experimental data on chemical wave propagation and pattern formation in nonuniform media...
with the Belousov-Zhabotinsky reaction
Belousov-Zhabotinsky reaction
A Belousov–Zhabotinsky reaction, or BZ reaction, is one of a class of reactions that serve as a classical example of non-equilibrium thermodynamics, resulting in the establishment of a nonlinear chemical oscillator. The only common element in these oscillating systems is the inclusion of bromine...
showing spiraling colored waves.)
Basic principles
The wave properties of the BZ reaction means it can move information in the same way as all other waves. This still leaves the need for computation, performed by conventional microchips using the binary codeBinary code
A binary code is a way of representing text or computer processor instructions by the use of the binary number system's two-binary digits 0 and 1. This is accomplished by assigning a bit string to each particular symbol or instruction...
transmitting and changing ones and zeros through a complicated system of logic gate
Logic gate
A logic gate is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and...
s. To perform any conceivable computation it is sufficient to have NAND gates
NAND logic
NAND gates are one of the two basic logic gates from which any other logic gates can be built. Due to this property, NAND and NOR gates are sometimes called "universal gates". However, modern integrated circuits are not constructed exclusively from a single type of gate...
. (A NAND gate has two bits input. Its output is 0 if both bits are 1, otherwise it's 1). In the chemical computer version logic gates are implemented by concentration waves blocking or amplifying each other in different ways.
Current research
In 1989 it was demonstrated how light-sensitive chemical reactions could perform image processingImage processing
In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or, a set of characteristics or parameters related to the image...
. This led to an upsurge in the field of chemical computing. Andrew Adamatzky at the University of the West of England
University of the West of England
The University of the West of England is a university based in the English city of Bristol. Its main campus is at Frenchay, about five miles north of the city centre...
has demonstrated simple logic gates using reaction-diffusion processes. Furthermore he has theoretically shown how a hypothetical "2+ medium" modelled as a cellular automaton
Cellular automaton
A cellular automaton is a discrete model studied in computability theory, mathematics, physics, complexity science, theoretical biology and microstructure modeling. It consists of a regular grid of cells, each in one of a finite number of states, such as "On" and "Off"...
can perform computation.
The breakthrough came when he read a theoretical article of two scientists who illustrated how to make logic gates to a computer by using the balls on a billiard table
Billiard-Ball Computer
A billiard ball computer, also known as a conservative logic circuit, is an idealized model of a reversible mechanical computer based on newtonian dynamics, proposed in 1982 by Edward Fredkin and Tommaso Toffoli...
as an example. Like in the case with the AND-gate, two balls represents two different bits. If a single ball shoots towards a common colliding point, the bit is 1. If not, it is 0. A collision will only occur if both balls are sent toward the point, which then is registered in the same way as when two electronic 1's gives a new and single 1. In this way the balls work together like an AND-gate.
Adamatzkys' great achievement was to transfer this principle to the BZ-chemicale and replace the billiard balls with waves. If it occurs two waves in the solution, they will meet and create as a third wave which is registered as a 1. He has tested the theory in practice and has already documented that it works. For the moment he is cooperating with some other scientists in producing some thousand chemical versions of logic gates that is going to become a form of chemical pocket calculator.
One of the problems with the present version of this technology is the speed of the waves; they only spread at a rate of a few millimeters per minute. According to Adamatzky, this problem can be eliminated by placing the gates very close to each other, to make sure the signals are transferred quickly. Another possibility could be new chemical reactions where waves propagate much faster. If these teething problems are overcome, a chemical computer will offer clear advantages over an electronic computer.
An increasing number of individuals in the computer industry are starting to realise the potential of this technology. IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
is at the moment testing out new ideas in the field of microprocessing with many similarities to the basic principles of a chemical computer.