Thursday, May 31, 2012

What is Energy?

I posted this on my departmental notice board because i was tired of seeing the board empty of tech post and mostly because i was in the mood for writing something " techy " and i feel it is only natural to also post it on this blog as well.

So what exactly is energy? Well as Albert Einstein rightly put it “ energy and matter are different forms of the same thing ”. He was of the opinion that every bit of matter is energy evident in his famous formula ( E = mC2 ). We humans have been able to convert matter into energy ( although very inefficiently and with a lot of losses to a form most common to us – HEAT ), but what about the other way round….
 Presenting ANTIMATTER – the wonder particle only created and captured in small amounts for now using a particle accelerator and a penning trap ( just a set of magnetic traps, using superconducting magnets cooled to temperatures near absolute zero – the ALPHA researchers in CERN used an octupole magnet, produced by the current flowing in eight wires, to create the magnetic field. The container is lined with such magnet and arranged in such a way that its magnetic field is strongest close to the wall and weakest at the center of the container/trap).
A positron discovery
This brings us to another important question, so what then are antimatter particles? The term antimatter was first introduced by Arthur Schuster in 1898. In his two letters to Nature, Schuster hypothesized antiatoms, whole antimatter solar systems and discussed the possibility of matter and antimatter annihilating each other. The modern theory of antimatter began in 1928, with a paper by physicist Paul Dirac. In particle physics, antimatter is an extension of the concept of the antiparticle to matter. Antimatter is composed of antiparticles in the same way that normal matter is composed of particles.
Trapping antimatter is tricky. When matter and antimatter get too close, they destroy each other, in a kind of explosion, leaving behind the energy - we could harness - which made them. The challenge is cooling the atoms off enough, 272 degrees below zero; so that they are slow enough to be trapped in a magnetic storage device.
An antihydrogen atom is made from a negatively charged antiproton and a positively charged positron, the antimatter counterpart of the electron.
More than 99.9% of the mass of neutral antimatter is accounted for by antiprotons and antineutrons. Their annihilation with protons and neutrons is a complicated process. A proton-antiproton pair can annihilate into a number of charged and neutral relativistic pions. Neutral pions, in turn, decay almost immediately into gamma rays; charged pions travel a few tens of meters and then decay further into muons and neutrinos. Finally, the muons decay into electrons and more neutrinos. Most of the energy (about 60%) is carried away by neutrinos, which have almost no interaction with matter and thus escape into outer space.
The effect of a large antimatter bomb would likely be similar to that of a nuclear explosion of similar size. The reacting antimatter would release about half of its energy in a form immediately available to the environment, superheating the casing and components of the bomb and the surrounding air, and turning it into ultra-hot plasma which then emits Thermal Radiation in the full EM spectrum. A quantity as small as a kilogram of antimatter would release 1.8×1017 J (180 petajoules) of energy. Given that roughly half the energy will escape as non-interacting neutrinos( they are sub-atomic particles found in the neutron of an atom), which gives 90 petajoules of combined blast and EM radiation, or the rough equivalent of a 20 megaton thermonuclear bomb.
Antimatter production and containment are major obstacles to the creation of antimatter weapons or using it as an Energy source. One gram of antimatter annihilating with one gram of matter produces 180 terajoules as much energy enough to power an average city for an extensive amount of time.
In reality, however, all known technologies for producing antimatter involve particle accelerators, and they are currently still highly inefficient and expensive. The production rate per year is only 1 to 10 Nano grams. In 2008, the annual production of antiprotons at the Antiproton Decelerator facility of CERN was several picograms at a cost of $20 million. Thus, at the current level of production, an equivalent of a 10MT hydrogen bomb, about 250 grams of antimatter will take 2.5 million years of the energy production of the entire Earth to produce. A milligram of antimatter will take 100000 times the annual production rate to produce (or 100000 years), It will take billions of years for the current production rate to make an equivalent of current typical hydrogen bomb.
Since the first creation of artificial antiprotons in 1955, production rates increased nearly geometrically until the mid 1980's; a significant advancement was made recently as a single anti-hydrogen atom was produced suspended in a magnetic field. Physical laws such as the small cross-section of antiproton production in high-energy nuclear collisions make it difficult and perhaps impossible to drastically improve the production efficiency of antimatter.
(Photo: CERN / Niels Madsen)
A photo of the ALPHA experimental apparatus
Even if it were possible to convert energy directly into particle/antiparticle pairs without any loss, a large-scale power plant generating 2000 MWe would take 25 hours to produce just one gram of antimatter. Given the average price of electric power around $50 per megawatt hour, this puts a lower limit on the cost of antimatter at $2.5 million per gram. They suggest that this would make antimatter very cost-effective as a rocket fuel, as just one milligram would be enough to send a probe to Pluto and back in a year, a mission that would be completely unaffordable with conventional fuels. Incidentally the cost of the Manhattan Project (to produce the first atomic bomb) is estimated at $20 billion in 1996 prices. Most scientists however would doubt whether such efficiencies could ever be achieved.
The second problem is the containment of antimatter. Antimatter annihilates with regular matter on contact, so it would be necessary to prevent contact, for example by producing antimatter in the form of solid charged or magnetized particles, and suspending them using electromagnetic fields in near-perfect vacuum. Another, more hypothetical method is the storage of antiprotons inside fullerenes. The negatively charged antiprotons would repel the electron cloud around the sphere of carbon, so they could not get near enough to the normal protons to annihilate with them.
In order to achieve compactness given macroscopic weight, the overall electric charge of the antimatter weapon core would have to be very small compared to the number of particles. For example, it is not feasible to construct perhaps an energy core using positrons alone, due to their mutual repulsion. The antimatter energy core would have to consist primarily of neutral antiparticles. Extremely small amounts of antihydrogen have been produced in laboratories, but containing them (by cooling them to temperatures of several millikelvins and trapping them in a Penning trap) is extremely difficult. And even if these proposed experiments were successful, they would only trap several antihydrogen atoms for research purposes, far too few for powering a small city or for spacecraft propulsion. Heavier antimatter atoms have yet to be produced.
Now imagine I have an antimatter particle, I only need to combine it with matter to generate energy to power the World! ( with obviously very reduced nuclear fallout (which can be contained with Lead lined reactors –potable reactors -) as compared to a fission or fusion reaction. Fellow Engineers or Engineers to be, if only we could develop a cheap way to create and store antimatter we will solve the world’s energy challenge ( I refuse to see a problem but a challenge). Shell estimated that by the year 2050, the world’s energy demand would have doubled. Why don’t we give the world a solution, I am equally working on many energy solutions (ideas from a 21 year old kid who wants to change the world).
An example of how an anti-matter reactor would look like

Energy is all around us – ( the universe, the Van Allen Belt, the Belts around Jupiter etc.) – and mostly in us – ( matter, the atom etc.) – all we have to do is open our eyes to see more clearly…

I hope I have stirred up somebody’s imagination, so until next time…

Additional Reference

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