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Monday, 26 March 2012

What is the Lifetime of a Star?

Stars come in varying shapes and sizes our Sun to VY Canis Majoris (the largest star we know of, 2100 times the radius of the Sun). However they can't stay stars forever so what are the processes that lead to their creation and their eventual demise?

During its lifetime a star goes through a multitude of large changes and there are many different ways for it to develop. This is called stellar evolution. There are three main stages that we have to look at. The creation of the star, what happens once it exhausts its supply of fuel, and what remains after this. So, how is a star formed?

A star starts as a large cloud of molecular gas and dust, called a nebula. Nebulae are also known as stellar nurseries as large amounts of starts are formed there. A lot of the most stunning and popularised pictures of astronomical objects that we would all recognise are of nebulae. Inside the nebulae some of the debris starts to be pulled together. The molecules break down and the gravitational potential energy they loose is lost as heat. As the process continues a larger and larger amount of heat is produced and as the molecules come closer to each other the pressure increases, eventually creating a protostar. A protostar is dissimilar to normal stars as they are just rotating extremely hot gas spheres. A lot of the development of stars relies on the mass of the original cloud that it starts with. There has to be more than a specific mass of gas before a star can start to form. James Jeans, a British physicist, created a formula that predicts the mass that a cloud would have to reach before it could start to contract:
Where n is the particle number density, m is the average mass of a gas particle in the cloud,
T is the temperature, and k is the Boltzmann's constant.
Though we may not use this formula much, it shows how basic the conditions have to be for a protostar to form, and explains, at a fundamental level, how abundant stellar activity is. Check out this video talking more about the formation and development of protostars.

The next stage of the process relies heavily on the mass of the protostar. When we measure the radius, or mass of stars, we use the radius and mass of the Sun:
 =  6.955 x 108m

If a star is massive enough, it will start hydrogen fusion but if the protostar is less then around 0.08 Solar masses (M) then the temperature never gets high enough. These are called brown dwarfs. If a brown dwarf is heavier than 0.0125 Mthen it fuses deuterium, an isotope of hydrogen with one neutron, rather than conventional hydrogen which has none. This process requires a lot less energy than hydrogen fusion, but does not produce nearly as much. These brown dwarfs as well as other sub-stellar objects (objects larger than a planet but smaller than a brown dwarf) do not shine very brightly and slowly cool and die.
On the other hand, in other more massive protostars, they reach 10 million ºK (degrees kelvin). At this temperature there is enough energy for hydrogen fusion to take place. When two hydrogen atoms clash, a sort of beta decay takes place. We have already talked about beta minus decay due to the weak interaction. This is beta plus decay, which is very similar, a sort of mirror image of beta minus decay. Due to the large amount of energy, One of the hydrogen atoms, a proton, decays through the weak force to become a neutron whilst releasing the anti-matter version of an electron (called a positron), an electron-neutrino and excess energy. This sort of decay is not common outside of stars as it requires a lot of energy.
Source: https://kjende.web.cern.ch/kjende/en/index.htm
Beta + decay
The passage of time is along the x-axis
When this happens, a atom of deuterium is produced. The positron produced in this decay annihilates with an electron. This produces two gamma ray photons and even more energy. After that, the deuterium fuses with another atom of hydrogen, to form an atom helium-3, another gamma ray photon, and a large amount of energy. This fusion can take place faster than the first stage, as it does not rely on the weak interaction. From that atom of helium there are three possible branches of fusion that could take place, these are called the pp I, pp II and pp III branches, pp staring for proton-proton. pp I is the simplest branch. Two of these helium-3 atoms fuse to create an atom of helium-4, an atom of hydrogen and excess energy. pp II and pp III are chain reactions, all resulting in the creation of heavier elements, though they are much less common:
pp II chain reaction (source:Wikipedia)

pp III chain reaction (source:Wikipedia)
At the end of all of these processes, approximately 0.7% of the original mass of the protons has been lost as energy. The energy released as gamma rays interact with electrons and protons and causes the heating of the interior of the star. This heat creates enough outward pressure to stop the star collapsing in on itself.

After a star runs out of hydrogen it starts to contract. It contracts until electron degeneracy, the inability for any electrons to be in the same quantum state, means that it cannot contract any further or it becomes hot enough for helium to start to fuse. However, what actual occurs relies on the mass of the star. A star which is less than 0.5 M☉ will not be able to fuse helium due to there not being enough pressure. These stars are called red dwarfs and the closest star to our solar system, Proxima Centauri, is one. After a very long time, they become white dwarfs. Stars with a mass of roughly 0.5 - 1 M become red giants. Red giants have very large radius, whilst having a relatively low surface temperature.  There are two main types of red giant, RGB stars, and AGB stars. RGB stars have a core of inactive helium, and hydrogen fusing into helium outside of the core. The other type, AGB, creates carbon through helium fusion in the triple-alpha process:
Triple-alpha process
In both types, the star is forced to expand hugely. When the Sun becomes a red giant in a few billion years, it will expand to at least 200 times its current radius. As the star is cooler than before, the light it produces is redder, resulting in its name.
If helium fusion starts to take place there will be a helium flash, where a huge amount of energy is realised. After all the helium has been fused, the star is left with a core of carbon and oxygen. The star changes size and temperature and there is a large amount of mass loss through stellar winds. The mass lost is usually in heavy element rich gas, particularly oxygen and carbon, which can sometimes clump together as planets.
The process is different for more massive stars. If a star is massive enough that helium fusion begins before electron degeneracy becomes prevalent, then it is likely that it will collapse into a type II supernova. A supernova is a pretty much an explosion caused by the quick collapse of one of these massive stars. Other massive stars may instead become red supergiants, extremely large red giants that produce a larger amount of heavier elements then normal red giants. Hot gasses are also expelled from these stars, and the atoms and molecules can form atoms around a second generation star.

After all of a star's fuel supply has been burned out, there are three different forms it can take, depending on its mass. If the star originally had a mass of 1 M☉ then it will form a white dwarf of mass 0.6 M. White dwarfs are very dense, stable stars, kept stable only due to the fact the electron degeneracy stops them from collapsing. The star does not create any more energy, but radiates its heat for billions of years. A white dwarf is so hot at its formation that it looses a lot of its energy in the form of neutrinos. Reasonably large white dwarfs, with a mass of a few solar masses, would be composed of oxygen, neon and magnesium, and medium sized white dwarfs, around the the sun's mass, will be composed of carbon and oxygen. Any smaller than this and the white dwarf will be mainly composed of helium. However, if a white dwarf's mass increases above something called the Chandrasekhar limit, then the star will collapse. This can lead to the ignition of carbon and oxygen or the creation of a neutron star, which we will talk about soon.
Another possibility for when a star runs out of fuel is that it will immediately collapse into a neutron star. This is through a process called electron capture. If the pressure is high enough a proton can absorb an electron and become a neutron. The star becomes a very dense ball of neutrons with a thin layer of other matter on top. These neutron stars are incredibly small whilst having a mass regular for a red giant and spin incredibly quickly, the fastest at over 600 revolutions per second. Some neutron stars emit detectable radiation when their axis is lined up with the earth, and these are called pulsars.
The last possibility is only only applies to very massive stars. If the star is massive enough, the star will be compressed to have a radius below the Schwarzchild radius. The Schwarzchild radius is the radius at which, if all the matter of an object of choice were to fit into a sphere with that radius, no light would be able to escape from its surface and is expressed by the formula:
c is the speed of light in a vacuum, G is the gravitational constant and m is the mass of the object
And what is an object from which no light can escape? A black hole! We have already talked about black holes briefly. They are objects of such high density (sometimes infinite, called a singularity) that not even light can escape from them and because of this all we know about them is that they exist. 


We hope you enjoyed this post. If you have anymore questions, you can follow us on twitter, @theaftermatter, email us at contactus@theaftermatter.com or search "The Aftermatter"on Facebook. We really like hearing your feedback or just talking about the posts or other physics and maths. 

Ned Summers.

Check out our last two posts:
What is the Theory of Everything? (Part 2): String Theory - The first look into a theory that could possibly become a theory of everything. 
What are Superconductors? - What are superconductors and how will they change the way we live our lives?

Sunday, 18 March 2012

What is the Theory of Everything? (Part 2): String Theory

Part two of our series on the Theory of Everything, click here for the first. String theory is one of the leading candidates for a theory of everything, but what actually is it? And, what is the answer to the age old question, how long is a piece of string?

This week, we were very lucky to be able to go and see theoretical physicist at Imperial College, London, Dr. Toby Wiseman, do a talk called "Black Holes, The Big Bang, Quantum Mechanics and String Theory". He talked about general relativity, which he lectures about on a regular basis, and quantum physics, which led onto String Theory. It was a fascinating talk and we had the pleasure of being able to go to lunch with him afterwards, along with some others that attended the talk. So, what is String Theory? And no, it isn't that kind of String Theory!

We have talked about particle physics before. In the post we talked about the particles in the standard model, one of our most advanced particle theories at the moment. I described these particles as "fundamental"in the sense that they can not be broken down any further. Conventionally they are thought of points. And as a point they have no width, length or depth. These points can move about through space-time, and have properties like charge and spin, but that is all. At its most basic level, String Theory states that these particles are not just points, but instead strings. These strings have a length, 10 x 10-35m, which is also know as the planck length, but no width. Because they are no longer points, these strings can do more than just move through space-time, they can oscillate. However, because they are so small, these strings still appear to be point particles. The different properties of the string's oscillation changes what properties the particle has, and therefore, which particle it is.
So what is the importance of this? Well firstly, lets look a little into a bit of quantum mechanics. When electromagnetism and gravity were first described by physicists, both equations were similar in one way. Both the gravitational force and electromagnetic force were inversely proportional to the distance between the two objects. However, when physicists started to consider these forces at a very small scale, with point particles, they had to deal with distances of zero between the particles, and therefore infinite forces. Quantum mechanics lead to a solution to this for electromagnetism, based on the uncertainty principle, in that we can never know where a particle is exactly and so there isn't a proper singularity when the distance is 0. However, this couldn't work for gravity, as gravity was no longer described with the Newtonian equation, but instead by Einstein's theory of relativity. Gravity could not be adapted to fit in with this, as we have talked about in the first part of this series, but this is where String Theory becomes relevant. Unlike in quantum field theory, String Theory requires a force of gravity. String theory appears to be able to describe almost everything very well. So how do these come about? Well lets continue with our  quantum mechanics. When we describe interactions between particles, we use Feynman diagrams.
A Feynman Diagram showing the decay of a proton to a neutron through the weak force. One of the down quarks (D) decays to an up quark (U) by emitting a W- boson (W-) which then becomes a antielectron neutrino (Anti-Ve) and a electron (e-).
Feynman diagrams show each particle as a line. At the part were two lines intersect, there is some sort of interaction, and the wavy lines are the bosons that carry these interactions. All the particles move along a axis of time. The other axis is that of space. Quantum theory leads to problems, there are infinities that arise when you try to think about interactions in this way, and it is this that leads to what we saw before with the inability to integrate gravity. However, when using String Theory, we can replace these lines with cylinders:
Two Particles moving through space. On the left we see it as a string, as apposed to a point,  like on the right.
If we look at it like this, our Feynman diagrams change a little: 
Source: Learner.org
We see now that when strings interact, they merge and break in such a way that would lead their oscillation to change, and therefore can change the particle that they are. More interesting, is that now that there is always a distance between the different parts of the strings, there are none of the infinities that occur with point particles.

There is more to String Theory than that. There are five different types of String Theory, Type I SO(32),Type IIA, Type IIB, SO(32) Heterotic and E8 x E8 Heterotic. They all differ in individual ways, but have one thing in common. They require 10 space-time dimensions, instead of the 4 that we are used too. Before this, we have to discuss the idea of Dp-branes. A brane is, in essence, a group of dimensions that open strings can be attached to either at one end, or both. Only open strings attach to these branes, whilst closed ones, the main one being the graviton, are not attached. The p shows the number of dimensions. Here is an example of a D2-brane:
Source: http://www.sukidog.com/jpierre/strings/dbranes.htm

However, even closed strings can interact with these branes:
Source: http://www.sukidog.com/jpierre/strings/dbranes.htm
Depending on which version of String Theory you look at, there are many different branes. These branes influence many things to do with these strings. We sometimes can say that we live in a D4-brane, and back in September when the now-discredited result that neutrinos had travelled faster than light emerged, one of the possible explanations was that the neutrinos had taken a shortcut through another brane/dimension.

The last, very distinctive, difference between String Theory and the standard model is its predictions for "supersymmetry". Each particle will have a related superpartner, these particles are very similar to their superpartners, but one is a boson, and one is a fermion.

String theory is one of the most advanced candidates for a theory of everything we have. It seems, though, that it will be a long time until it is either verified or disproven. As the strings are supposed to be so small, they cannot be detected, and the energy required to create a state of quantum gravity is so heigh that it is unlikely to be reached for decades. The theory is incredibly complicated, we are only scratching the surface and if you want to find out more, please check out these sources that we used: 1 2 3. And here is a fantastic video on the subject:


We hope you enjoyed this post. If you have anymore questions, you can follow us on twitter, @theaftermatter, email us at contactus@theaftermatter.com or search "The Aftermatter"on Facebook. We really like hearing your feedback or just talking about the posts or other physics and maths. 

Ned Summers.

Check out our last two posts:
What are Superconductors? - What are superconductors and how will they change the way we live our lives?
Artificial Intelligence Composers: Can computers write music? - How are computers managing to use algorithms to create music that sounds like it was written by a regular human?
And the first in this series:
What is the Theory of Everything? (Part 1) - How can a theory describe everything? And are there philosophical implications if it can?

What are we posting about next:
What is the Lifetime of a Star? - Many of you will have learnt about how a stars life unfolds, but what are the basic processes behind it all?

Sunday, 11 March 2012

What Are Superconductors?

How will Physics change our world in the next 100 years? Today at The Aftermatter, we're looking at how superconductors will revolutionise our power supplies, and the impacts this will have.

Physics, considered by many to be a boring, inane, number-crunching field, seems to be the least likely place to find magic. But the magic of today is the physics of the future: in the next 100 years it will alter so definitively our society that, if we were to visit it today, we would consider it impossible. Yes, past dreams such as flying cars and robot housekeepers have not fully materialised, but imagine someone from 1912 visiting today’s society. They would see strange machines that display movies without a projector. They would see machines that could display almost any book ever published within 30 seconds. They would see telegraphs without wires that could understand you, and answer your requests. People would hand over money using cards made out of a material that hadn’t even been discovered yet. To the visitor from 1912, the present would be magic. It would be impossible. 2112 will be no different. Science fiction will be come science fact, not just confined to a geeky sector of the super-rich, but for everyone. Physics, more than politics, will change the course of the world over the next century, and we are blessed to be able to witness the start of it.

One technology about which a lot of research is already being done is superconductivity. A superconductor is a material that has no resistance to electrical current. Resistance is the friction of the electrical world. In this way, copper wire is analogous to road travel on Earth: the road and the air provide friction that opposes your motion. However, if you provided the same force in space, where there are no air particles or road to create friction, then you would continue moving until something stopped you: theoretically, you would never slow down! In this way, using a superconductor is like travelling into space. Current and resistance are linked in the following equation:

V=IR
Where V is voltage, I is current, and R is resistance. 
This means that in superconductors, where R is 0, with any voltage at all, the current (the rate at which electrons move through the material) is theoretically infinite, and thus the electricity can keep travelling without slowing down. 

The only problem with this is that at the moment, superconductors have to be extremely cold to work. The first superconductor that was discovered, Mercury, only works at 4° Kelvin, or about -269°C. Scientists have made a bit more progress since then on warmer superconductors. In 1986, scientists found that certain ceramics could also superconduct, and this time at much higher temperatures, such as 92°K (-182°C), and the current world record for the highest temperature superconductor is 132°K(-135°C), which is still far too cold for most purposes, but, crucially, it is warm enough to be cooled by liquid nitrogen, which is as cheap as milk. More recently, in 2010, a team of researchers lead by Yoshihiko Takano, during a rather boozy party in the laboratory, found that certainalcoholic drinks increase the superconductive temperatures of certain ceramics. Bizarrely, the alcohol itself seems to be nothing to do with the results: a mixture of water and ethanol had no effect on the ceramics. Experiments are still ongoing as to why these drinks have such an effect. Some have concluded that red wine improves the efficiency of both superconductors and academic researchers!

 Considering all this, within the next 60-100 years, it is likely that room temperature superconductors will be a reality. The consequences of this would be huge. Room-temperature superconductors allow for use in everyday life. Because superconductors are so efficient, electricity would become incredibly cheap. Currently, 30% of electricity is wasted in transmission between the power plant and the home, but superconductors would reduce this number to zero. This isn’t even considering the wastage that built in to our appliances in the form of copper wires. It would almost completely solve the energy crisis. But there is one thing that superconductors are exceptionally good at: electromagnetism. Strong electromagnets require huge amounts of electricity, but with superconductors this will become a very manageable and affordable amount to use.

In the same way that over the last century, electrical wires were proliferated into our society so that every wall contains them, once superconductors exist, electromagnets will be put into every floor, every wall and every road. If you then put electromagnets into, say, pieces of furniture, then your days of lifting sofas are over: you simply turn on the electromagnets and the sofa will hover into the air! You could then use a control pad to manipulate the sofa as you like, and then gradually turn off the magnets to lower it down gently. Some may think that this would have unwanted side effects, such as cutlery flying across the room as you’re moving the armchair, but, using magnetic shielding materials already in existence such as mu-metal, you can carefully direct the magnetic force to affect only the object you want. It would be a real-life manifestation of Harry Potter’s Wingardium Leviosa, what is magic today will be common place by the 2100’s.

Another use of these electromagnets will be in transport. As well as virtually eradicating resistance, electrical friction, superconductors will go a long way towards reducing physical friction in transport. By placing electromagnets on train tracks and in the train itself, it is possible to make the train hover just above the line, and then move without touching the actual track, meaning that there is no friction between the train and the track, and thus it can move much faster. This already exists: it is called MagLev, and is used as part of Japan and China’s rail systems. The trains in Shanghai run at over 268mph regularly, which is faster than any Formula 1 car, and in a test run reached a top speed of 311mph. The only thing stopping it spreading further is the cost of powering these powerful magnets, which would be reduced to almost zero with the dawn of room-temperature superconductors. There is no reason we would have to restrict ourselves to trains, either. If we placed electromagnets in the road and in cars, then our dream of the hover car would be complete. We would no longer need petrol, only electricity, which would be cheaper and more efficient than ever before. We will finally fulfill the predictions of countless science fiction writers: these wouldn’t just be wacky, gimmicky flying cars, these would actually have a purpose: they would be more efficient, and they would be everywhere. Great physics is sometimes spoilt by economics, but this is one case where they would walk hand in hand.

This is just one way in which Physics will change our future. Physicists make dreams realities; they make impacts that will last longer than that of any government. So much of our society today is shaped by technology; the Internet a prime example: it hasn’t just solved a problem, it has sculpted the world and society in a profound way. Technology will continue to do that, and it is Physics that provides it. Physics is ‘magic,’ physicists will be the ones recreating Hogwarts, and it will be the physicists of today who shape the world of tomorrow. 

We hope you enjoyed this post. If you have anymore questions, you can follow us on twitter, @theaftermatter, email us at contactus@theaftermatter.com or search "The Aftermatter"on Facebook. We really like hearing your feedback or just talking about the posts or other physics and maths. We hope you enjoyed this post.

Theo Caplan.

Check out our last two posts:
Artificial Intelligence Composers: Can computers write music? - How are computers managing to use algorithms to create music that sounds like it was written by a regular human?
What is the Theory of Everything? (Part 1) - How can a theory describe everything? And are there moral implications if it can?

What are we posting about next:
What is the Theory of Everything? (Part 2): String Theory - The first look into a theory that could possibly become a theory of everything. 

Sunday, 4 March 2012

Artificial Intelligence Composers: Can computers write music?

Music seems to be such a human thing, and, although as we’ve shown in our previous posts it does follow mathematical patterns, a computer couldn’t ever write good music could it? And if it could we’re miles off, right? Think again.



Much work has been done on Artificial Intelligence, particularly in Linguistics, but very little has been done in other, more creative areas, such as music. This is partly because it is difficult: there are no set rules to program; such programming would require great musical insight from the coder, and partly because of the emotional effect that music has on people. All advanced musicians achieve the standard they do because they feel the emotion in pieces, and because they put those emotions into their own performance and writing. Artificial Intelligence challenges that. Computers (as of yet) don’t have feelings: they don’t have emotions. How could a computer write music successfully when it had no emotional message to send? There were not many musicians who believed that this field would lead to any results.

One man who did believe, however, is David Cope. Born in 1941, he was a conventional composer, with a huge passion for music. However, when commissioned to write an opera in 1980, he suffered from a terrible case of writer’s block. He had hit a complete creative dead-end.

Desperate, he had the idea of creating a ‘virtual David Cope,’ a computer programmed with certain rules that he tended to follow in his compositions to try and create new material, which he named “Experiments in Musical Intelligence,” or “Emmy” for short. It didn’t take long before he realised that this was simply too big a task, but he didn’t give up completely. He decided to try to code the computer to harmonise Bach chorales.

For those of you that don’t know, Bach chorales are 4-part vocal hymns that obey certain harmonic rules, (e.g. no parallel fifths or octaves, thirds fall, leading notes rise) and harmonising a single line into a full chorale is a common task for music students. The tight, rule based nature of it lent itself very nicely to automation, and it wasn’t long before the computer could accurately harmonise these chorales, following all the rules. However, the results were only of a level comparable to a mediocre music undergraduate, and could certainly not be compared with Bach himself. The music lacked drive, it lacked passion: it felt mass-produced.

David Cope realised that Bach didn’t always follow his own rules. When they needed to be broken, he broke them. But how do you tell a computer to break its own rules? How will it know when to do so?

This was Cope’s masterstroke. He input all 371 original Bach chorales into the computer, and got it to analyse them and derive its own rules. This approach is known as data-driven programming. The computer still needed to be told exactly what to analyse though! The initial results sounded good when played as extracts but lacked a logical pattern throughout the piece. To combat this, Cope came up with many ingenious analytical solutions: analysing how often a certain motif has been repeated, or how long a piece should remain in the same key. The results were astonishing. When first performed in 1987, it was played alongside genuine Bach chorales. The audience, full of musical and academic luminaries, were polled on which pieces were Bach’s and which were Emmy’s. They couldn’t tell the difference. One could argue that this means that Emmy passed the Turing test. Not only this, but Emmy was fast. She composed over 5000 chorales in half an hour, 15 times as many as Bach produced in his entire lifetime.

He expanded Emmy from the basic, prescriptive Bach chorales to incorporate many other, more complex composers, from Mozart to Scott Joplin, and even himself. Once again, many pieces were indistinguishable. Below are excerpts from two ‘Chopin’ Mazurkas, one genuine and one composed by Emmy. Can you tell the difference? Which one is genuine? We will tell you at the end which is Emmy, but how about you take the poll on the sidebar before you find out?



This has massive implications for many musicians. If a computer can write music just like, and as good as, theirs, then what is it that makes their music so great? Most identified with the soul and passion that they put into their works, but the computer can’t do this! The computer is just following mathematical patterns and algorithms. Does this mean that, ultimately, Mozart, Debussy, Beethoven, Chopin, and every other composer in the world were just subconsciously following similar algorithms?

 Cope’s answer is an unreserved yes. He says that the emotion isn’t in the music itself, but that it triggers the emotion in our own heads. As the songwriter Irving Berlin said, “Life is 10% what you make it, and 90% how you take it.” A human composer may feel they are putting in the emotion themself, because they are feeling that emotion whilst writing it, but the emotion is triggered in them in the same way it is triggered in the listener. A computer could trigger those notes in the same way. However, people’s perceptions are very important: people are very biased when it comes to computers and emotion. When one music professor was played a piece by a later version of Emmy at a concert, having not been told it was written by a computer, he described it as “one of the most intense musical experiences of my life.” However, a year later, when played a recording of that same piece at a presentation by Cope about his work, this time knowing it was computer generated, he said, “You know, that’s pretty music, but I could tell absolutely, immediately that it was computer-composed. There’s no heart or soul or depth to the piece.” For some people, the emotional origin of the music is important, for others it is only the result.

Cope found it difficult to get Emmy a recording contract. It was just so controversial that agents wouldn’t let their artists touch it. Many also felt that with so many thousands of pieces being generated by her, the pieces didn’t seem special enough. There was simply an overload.

Cope had to move on. In 2004, he deleted Emmy. He kept the original algorithm backed up, and a small sample of the database, but for all intents and purposes, she was gone. He replaced her with the more human sounding "Emily Howell," so named so that critics would not realise instantly that she was a computer. He used all of the scores used by Emmy as a starting point, and fed them in. Emily then has a musical conversation with Cope: she comes up with a phrase, and she responds to his positive or negative feedback. Emily learns his style, and gradually creates better and better music. Cope understandably does not want to give away to many of the precise details of how Emily works, but the results are truly amazing: original, moving music. Her first album, "From Darkness, Light", is available on iTunes and Spotify.

This music moves me deeply; I don't care that it comes from a computer. It is excellent, and innovative, it's just that a computer made it rather than a human.

Emily Howell doesn't just do pastiches, her style is recognisably unique, and adapts depending on Cope's feedback. For this reason, Cope feels that the program is essentially an extension of him: he is just teaching her his biases, and she is speeding up the job for him. In fact, she may be better at the job with him: the element of randomness in the rule-breaking is very important in music, and humans are notoriously bad at being random. Almost everything we do is extremely predictable. In a way, computers are better at coming up with original ideas than we are.

Emily Howell may make you look at music differently. Music is emotional for us, but that emotion comes from us, not from the music itself. The music merely triggers that. I write music to express emotions and feelings, but I listen to music to feel, myself, whether or not someone intended me to feel it. That's not important to me.

Emily Howell is an absolute miracle of AI. She is probably the first program that could really make people feel, that could bring people to tears, and Cope is a genius. He has found the essence of music, and reproduced it like never before, and we can only wait and see what he and Emily will do next. And by the way, the second of the two sound clips was Emmy.

We hope you enjoyed this post. If you have anymore questions, you can follow us on twitter, @theaftermatter, email us at contactus@theaftermatter.com or search "The Aftermatter"on Facebook. We really like hearing your feedback or just talking about the posts or other physics and maths. We hope you enjoyed this post.

Theo Caplan.

Check out our last two posts:
What is the Theory of Everything? (Part 1) - How can a theory describe everything? And are there moral implications if it can?
What are Imaginary Numbers? - What is a imaginary number? Surely a number, by definition, is a unit of measurement, and if it is, how can a number not exist?

What are we posting about next:
What Are Superconductors? - What impact will a wire with no resistance have on our society and our technology?