Entropy, Energy and Order in the Universe | Energy Matters

Entropy, Energy and Order in the Universe
It is easy to get caught up in discussions over what types of energy we should use, and how we should use it. The problem with such discussions is that they gloss over some of the fundamental concepts of physics that should be the real drivers of our decision making process.
Let’s talk about the laws of thermodynamics. These laws originated during the steam age, where engineers puzzled over how to get more energy (work) out of steam engines. Over time a number of great scientists, Maxwell, Carnot, Boltzmann, Lord Kelvin, and others sorted out these fundamental laws. Eventually it was realized that these laws represent an even bigger concept – entropy.
What is entropy? It is simply the degree of disorder and randomness in the system.
So, what exactly is “order”? Think of it is “organized”. Solids are more ordered than liquids, which are more ordered than gasses. Large complex molecules (say, chlorophyll) are more ordered than simple ones (oxygen, water, etc.). Matter is more ordered than energy. Atoms themselves have a tremendous amount of order within them – think about how precisely neutrons, electrons, and protons are arranged and balanced within an atom.
Any time order is changed to disorder, energy is generated. Therefore if atoms are destroyed, energy is generated and entropy increases. If bonds within complex molecules are broken, energy in generated and entropy increases. If the orderly directional flow of atoms is disrupted, energy in generated and entropy increases
The universe, without exception, is moving from a state of order to disorder.
This statement leads to confusion – our everyday experience with reality shows entropy being reversed. For example, solar energy hits the leaf of a tree, and is used to create complex carbohydrates. Using lower order energy to create greater order in the carbohydrates of a leaf seemingly violates the laws of thermodynamics.
Except, that it doesn’t. To generate that ray of light, inside the sun, 600 million tons of hydrogen per second is converted to energy. This is a massive flow of order (the atoms) to disorder (energy). The leaf of a tree converts a tiny percentage of this disordered energy back to order. Combining the two together shows that, overall, there is still a massive flow of order to disorder.
Looking up at the night sky what you see are entropy generating machines – the stars are destroying order on a massive scale.
This example illustrates two fundamental concepts – one is that while the flow of entropy is always from order to disorder, you can have eddies in the current where order is created or accumulated. These are important, but are very small in relation to the universal flow toward greater entropy.
Why is atomic energy so much more powerful than all other forms of energy? A cubic meter of uranium can generate 3 million times more energy than a cubic meter of coal. Why? Well the fission reactor destroys matter by converting it to energy. It is going in the direction of the entropic flow!
Coal represents fossilized solar energy. It is part of the eddy toward more order as part of the massive order destroying activities of the sun. Complex molecules captured a small (1%) of the suns energies, over thousands or millions of years. That is what we are utilizing – the ancient scraps of the leftovers of nuclear fission in the sun.
We can rank all forms of energy based on their change in order to disorder. Remember, when we use energy we are consuming orderliness, and increasing entropy. So here they are ranked:
Electromagnetic energy (solar)
Motion of atoms (wind, tides, hydropower)
Chemical breakdown of complex molecules (wood, oil, gas, coal)
Breakdown of atomic structures (fission, geothermal, and fusion)
Complete destruction of atoms (antimatter)
Why is geothermal lumped with fission and fusion? That is because the heat of the earth is largely a byproduct of natural radioactive decay, which is fission.
Now fusion, fission, geothermal, and antimatter are entropically positive – meaning they are deriving their energy from destruction of order in atoms. Fossil fuels, wood, hydropower, and wind power are entropic eddies – energy from entropic positive sources that has been incidentally and accidentally concentrated and can be harvested. Solar represents degraded order at its lowest form – we are converting one form of energy (visible light) to a lower form (infrared light), harvesting the tiny amount of remaining order in the system.
Strangely, the more entropy already in the energy source, the more order must be placed into our energy harvesting mechanisms! Let’s rank these in how easy it is to harvest energy from the energy source?
Complete destruction of atoms (antimatter)
Breakdown of atomic structures (fission and fusion and geothermal power)
Chemical breakdown of complex molecules (wood, oil, gas, coal)
The motion of atoms (wind, tides, hydropower)
Disordered energy (solar)
What?! That doesn’t make any sense – fission is very hard to do, while solar is so easy!
Nope. What does it take to turn antimatter into energy? Nothing – it spontaneously turns into energy in the presence of matter. It is so destructive that no antimatter remains in our corner of the universe! It has all degraded to energy.
Fusion? Hard to do on earth, but look up at the stars – there are trillions of fusion reactors floating around in space. All you need is a great big ball of atoms lighter than lead. That is it.
Fission? Atoms naturally decay, but to get real energy, you need to collect the right sort of atoms together. This can and has happened naturally (yes there are natural fission reactors). Why were old atomic reactors were called “atomic piles”? They were literally piles of uranium atoms!
So we have already progressed from doing nothing at all, to getting a big ball of atoms together, to getting just the right kind of atoms together. Why is nuclear power so expensive? To protect us from the vast amounts of energy released. What is the primary purpose of out reactor? To control the energy production rate of the uranium atoms. If left alone, they would generate too much energy and destroy the reactor. Why don’t we have fusion on earth? It is an anomaly – we can’t get a big enough ball of atoms together. If we could, it would happen spontaneously. So it is expensive to try and replicate those conditions without the giant ball of atoms.
Chemical breakdowns require a bit more finesse – we need to bring just the right atoms together, under the right conditions. Coal, wood, and oil won’t burn without oxygen, and an ignition source, in the right quantities. Instead of just uranium atoms, we need three kinds of atoms, carbon, hydrogen, and oxygen. Still, the system to harvest the chemical energy is relatively simple. We just need to combine the right atoms in the right conditions.
Hydropower? Now we need a more complex structure to harvest the energy. It its simplest form coal can generate energy by creating a big pile and lighting it on fire. In its simplest form, water power requires we construct and maintain a mechanismfor extracting the energy (say a water wheel). The level of order of the extraction system has to increase dramatically because the source of energy is more disordered to begin with. Wind power is worse than hydropower because air is a gas and is more disordered than water.
Lastly is solar energy. Solar panels are organized and engineered at the atomic scale. They are very highly ordered objects designed to harvest the remaining, marginal energy left in sunshine. Even the simplest solar harvester, a magnifying glass, requires that I refine a very special type of atom (silica), and shape it into a very specific design (a lens). My energy collection mechanism is highly ordered. It has to be.
And how does a leaf capture and convert solar energy to chemical energy? Well, by an exceedingly complex biomolecular design. And even that works at 1% efficiency.
From this vantage point a lot of things make more sense. What is the source of poor EROEI for RE? Simple, our extraction mechanisms must contain the order missing from the renewable energy sources. That costs energy. Looking at something like Ocean Thermal Energy Conversion (OTEC) – why doesn’t it work well? Because you are trying to make the disordered heat in the ocean even more disordered, which means you need a big, expensive ordered mechanism to do it. That ruins your EROEI. Why does wave energy not work well? Again, you are trying to extract remaining order from a highly disordered source. So you need a great big highly ordered mechanism to do it. Why is the efficiency of solar panels limited? Well, a lot of the energy is in the infrared, which means there is little order worth extracting.
Most of our questions can be resolved by just looking at energy in entropic terms. What is the amount of order being destroyed, and by what mechanism? Does the source of energy contain a high or low degree of entropy?
Short bio for Geo: I am a scientist with an MBA working for a large multinational consulting firm. I specialize in evaluating and permitting energy projects. I’ve worked all sides of the issue, as a consultant to the government and to private industry. After 30 years in the business, and the more I learn, I realize how much more I still have to learn.
54 Responses to Entropy, Energy and Order in the Universe
The essential physics of your excellent piece also explains why some currently peripheral technologies, albeit advanced fervently by selective parts of the green zealotry cannot be economically sensible pursuits.
In particular I am thinking of:
(1) carbon capture and reuse (to recreate complex molecules from what is a final combustion/oxidation product), even with the convenient but still flawed premise of the “reuse” part of being fuelled by renewable power and
(2) carbon dioxide extraction directly from air, where the driving force (i.e. concentration gradient) is laughably minuscule, thus leading inevitably to issues of scale.
I’ve been trying to understand these processes for potential space colonies. The idea is to take energy (very abundant) and use it to convert CO2 and Water into Sugars, and then convert sugars into something edible. That way you could feed a space colony without having to build protective environments for crops.
If a technique could be made, it could go some way to solving world hunger.
However, at the moment, all the research is the other way round – how can we grow crops better so that we can burn them to make energy.
Alternatively, solar power is harvesting heat at 6,000K, which is a rather higher form of energy – more ordered – than water at 550K (as in a nuclear PWR) or 850K (as in a super critical boiler).
This is partly governed by how we collect and the energy density. Nuclear reactions happen at tens of thousands of degrees, but we are limited by materials – so degrade it to 550K. There are designs for direct energy capture of alpha particles – variations of the awesome fission fragment rocket: https://en.wikipedia.org/wiki/Fission-fragment_rocket
The “order” of solar panels doesn’t really matter as we have been very good at creating order on a small scale – silicon engineering, or crystal formation. In this case, energy density has a larger role to play, and here solar is not great, but better than wind.
Put it all together, and solar power is now cheaper, KWh for KWh, than fossil fuels or nuclear. But of course, it’s not there most of the time (unless you’re in orbit – where within 2 AU of the sun, solar power is the default choice for power and will probably remain so), and especially in the winter in high latitudes, when it would be needed most.
Don,
Ireland found its savings of imported gas were much less than estimated, because their gas turbine plants operated at a much lower average efficiency due to more frequent start stops, idling at synchronous speeds and increased part load operation.
That also meant more fuel/kWh and more CO2/kWh.
Instead of the offset ratio being 1 to 1, it became 0.56 to 1, at 17% annual share of wind.
To-day’s wind share is higher.
Don, by the time you factor in the clean up and disposal costs added to production costs and rare earth mining etc the benifits become a lot less, add in the disruption costs and they become negative.
As Germany has found it it still didn’t reduce their CO2 output anyway, I am glad to say.
Of course China & India do not bother with cleaning up their mining and chemical outputs as we do in the West, so the Environment pays the cost rather than the producers.
Don,
Solar is a midday affair, about 9 to 4; outside those hours it is not worth talking about.
Lots of solar leads to instability of distribution grids, requiring batteries to dampen the variation, as in Southern Germany and Southern California
Alex , the steady-state centreline fuel pin temperature in a water-cooled reactor would be closer to 1300K , and drops off to around 800 K at the cladding. The 550K you mention is the coolant temperature and is therefore irrelevant to whatever point you seem to be trying to make.
As you mentioned nuclear reactions take place at many thousands of degrees K . Current materials limits for metals are around 1300K . SiC , tungsten as well as other carbon forms ( graphite, diamond ) are being explored for fission and fusion containment.
Your claim that highly ordered PV panels are now cheaper than FF or nuclear is also irrelevant to the discussion here , which is about EROEi and the ranking of sources of energy by their state of entropy.
Solar power harvested at 6000 degrees? Perhaps on the surface of the sun. On earth it take an hour to get a tan.
The more entropic the energy source, the more order the system needs in order to harvest that source. Sunshine on the Earth contains very little order.
Indeed – we are very good at creating order on an atomic scale. But it takes a lot of energy to create that order. In fact, creating order requires energy, it is one of the rules of thermodynamics. The result is energy harvesting systems that do not provide much of an overall net benefit. And because of the rules of the universe, it will always be this way – there is no improvement to solar panels that can fix this fundamental problem.
Try making a solar cell in your home garage. You can’t, at least, nothing except a very primitive one. Why not? You do not have the complex, highly ordered system necessary to build one.
Just look at the equations:
Solar: E = 0.3 E (solar cells are only able to harvest a small percentage of the existing energy).
Obtaining energy from some source depends on some previous process placing energy into that source. Thus, photosynthesis in plants, using energy from the Sun, concentrates energy into the form of wood, coal, oil, gas, which we release upon combustion. Energy produced by gravity as a proto-sun shrinks, heats gases (now plasma) to such high temperature, that they emit radiation (photons), which we on Earth can collect and use. Solar radiation produces kinetic energy in our atmosphere in the form of wind, which we can utilize. Energy released in fission or fusion releases the nuclear energy stored in those nuclei when they were formed in very energetic processes (Big Bang, stellar interiors).
The amount of energy that can be gotten out of any system is dependent on the amount of potential energy stored in that system, and some systems contain much more stored energy than others. Matter itself is highly concentrated (stored) energy. High energy particle accelerators can make the E=mc^2 equation go the other direction.
Just to clarify: “High energy particle accelerators can make the E=mc^2 equation go the other direction.” No, they can’t. They can use tremendous amounts of energy to create a very small amount of matter. In other words they can sacrifice a tremendous amount of order at one end to make tiny piece of order on the other. The result is a huge net loss.
We see this even in simple radioactivity experiments – tiny bits of matter are created when atoms split, but at the expense of greater order within the atom.
Which is exactly what plants are doing – harvesting a huge amount of entropy creation in the sun to generate a tiny amount of order on Earth.
There is, and always will be, a net loss of order and increase in entropy in the universe.
Thank you Geo – a very useful reminder that physics is often being “bastardised” in much of what they describe as the new wonder energy supplies.
What is even more surprising is to find that Physics that one took as gospel is not correct either. The Global Climate Models assume that CO2 acts like a blackbody with all the hard-wired relationships that flow from that. BUT – modern research shows that CO2 and water vapour (and much else) do not increase emissivity to the 4th power of temperature, and thus the blackbody laws of Kirchhoff, Planck, and Stefan-Boltzmann do not necessarily apply – as Dr. Robitaille tells us here
There has been discussions of using an osmotic pump to generate electricity, where fresh water meets sea water. In effect, “Reverse Desalination”, or “Reverse-Reverese osmosis”.
The weird thing is, salt dissolving in water is an endothermic process, which lowers the temperature. Yet salt still dissolves, because the entropy increases.
As far as I’m aware, an osmotic pump would be the only way of making electricity from an endothermic process. All by increasing entropy. If it were a carnot engine, it would have negative efficiency! It’s not a Carnot Cycle, but the efficiency is probably too low to be viable.
Well, it is likely, based on the laws of the universe, to be complex tail chasing. That is, the complexity and energy invested in the harvesting machine (it’s level of order) is likely to greatly exceed the value of the energy you could ever hope to harvest.
Look, we can “make” energy from practically anything. I could power the world with gerbils in little wheels, if I had enough of either. Would my EROEI be positive? The universe says no way.
Assume a calm ocean, pretty deep, and normal salinity.
Take a pipe, any reasonable diameter, with a semi-permeable membrane permeable to fresh water at the submerged end.
Fill the pipe with fresh water and submerge the membrane end to a depth where the differential pressure across the membrane exceeds the osmotic pressure of saline/fresh water. (The pressure is effectively the buoyancy pressure arising from the density difference of sea water and fresh water.)
Fresh water will now flow through the membrane and cause the water level at the top of the pipe to rise above sea level, until the excess head equalises the osmotic pressure at the membrane.
You can now draw off fresh water from the top of the pipe at a pressure head less than the full excess head and enjoy hydro power until the end of time! 😉
Geo, I like your explanation of entropy and energy. Perhaps you could turn your explanation talent to entropy and evolution. A young (Harvard? MIT?) professor has an theory about evolution being able to exploit the wrinkles in entropy/energy flow to create more order and explain why evolution progressed as fast as it does.
While entropy is steadily increasing in the universe, there is an interesting side effect. Since energy can not be destroyed (i.e. degraded further), and energy contains information, information is immortal, and is not being impacted by entropy. In other words, the more ordered a system is, the less information it contains.
Entropy generates information.
For example, you have a deck of cards, stacked neatly, and in order. How long would it take you to describe that system with enough information to replicate it exactly? Well, I just did. Now take that deck of card and toss it in the air. Describe the end result so that it could be replicated exactly. That is very hard to do. The more chaos there is in a system, the more “information” it contains. So by increasing entropy we are increasing information.
How does this apply to life?
Well life contains an immense amount of information. A single strand of DNA can contain 700 terabytes of information, although most contain much less (1.5 GB or about two CDs). But, in our cells there is massive redundancy, so each cell contains a complete copy of this information.
So, since the universe is trying to maximize both entropy (disorder) and information, one might argue that life is a side effect of that process, and that the purpose of life is to increase the retention of information, by encoding it into matter rather than energy.
Ergo, evolution is basically driven by the fundamental law of the universe that is increasing both entropy and information.
It is estimated that life appeared on earth some 100 million years after its formation. However, a single bacterium contains a lot of complex information. 100 million years is a long time, but I was always struck by how little life changed between the moment it evolved (100 million years after Earth’s formation), to the first eukaryotes to appear (1.5 billion years later). It seems like life evolved very rapidly, then very slowly. Also, if life evolved that easily, there should be complex life everywhere in the universe, and we should be easily able to recreate things in the lab. Neither of which has proven to be true.
Someone much smarter than me decided that information theory might have a good answer. Genetic material in DNA can be represented as information. Complex DNA would have more information, simple organisms with simple DNA would have less information.
What they found is that looking at the fossil record, the amount of information stored in DNA was doubling every 363 million years. In other words, every 363 million years, the DNA for newly evolved plants and animals will have twice as much information. This explains why the transition from prokaryote to eukaryotes took so long – we were at the bottom of the curve, low information, and it took many doublings to make the small transition. But it also suggests there is some fundamental rule or law at work here. A Moore’s law for life forms.
So rather than exploiting entropic eddies or wrinkles, one might argue that life is a natural byproduct of a universe that has increasing entropy AND increasing information. In this case maximizing information seems to take precedence.
Thanks Geo. Brilliant final line. These liberal/lefties who have degrees in social work, English Language etc. and who tell engineers that they’re wrong on “renewables” should read that part and think about it.
Geoff,
They likely read some of these lines, found them too challenging, moved on to more liberal pursuits to get easy As, then jumped on the RE/GW bandwagon to pester the engineers and scientists who toughen it out.
A very interesting post which reminded me of the physics I studied 50 years ago.
One thing jarred, however. I seem to remember being told back then that the Sun loses 4million tonnes of mass per second. How does this square with your “600 million tons of hydrogen per second is converted to energy“? Is my memory faulty or have I missed something?
Geo, many thanks for this thought provoking post. One of the things I like is the asymmetry between entropy of energy source and the order in gathering machines. It seems like combined cycle gas turbine may be about the optimum for man, quite simple, cheap and easy to build, really powerful. Moving to nuclear, the new challenge of containing all the energy. And perhaps this is why we may never master controlled fusion?
Following your thesis what preceded Big Bang must have been incredibly ordered.
A very important topic indeed, and forgive me for still not comprehending the order / disorder bit with repect to (potential-) energy.
The lowest state of energy is absolute zero, when all Brownian movements have seized.
This to me would represent the ultimate order, the position of the molecules now clearly defined.
At the opposite end of the spectrum: Extreme heat, where the movements of the molecules leave their positions utterly unpredictable, and to my simple mind hence disorder reigns.
Available energy, i.e. a low state of entropy, is a prerequisite for an ordered “state of affairs” in such phenomena as biological life, or industrial civilization.
Thus these phenomena as “ordered” require available energy to arise.
That this will infer that a physical state of low entropy / high available energy is an ordered one escapes me.
I would also argue that “complexity” is a more adequate term for these phenomena ( life, society ) than order.
At the end of the article this question to me completes the puzzle:
What is the amount of order being destroyed, and by what mechanism?
If order exists as an measurable amount in physical terms it must have a corresponing unit, to my knowledge no such unit exists?
“The lowest state of energy is absolute zero, when all Brownian movements have seized.
This to me would represent the ultimate order, the position of the molecules now clearly defined.” I agree.
“At the opposite end of the spectrum: Extreme heat, where the movements of the molecules leave their positions utterly unpredictable, and to my simple mind hence disorder reigns.” Okay. BUT. The hot ball of plasma is giving off heat at a prodigious rate. That radiation is traveling from the ball to the extreme corners of the universe at the speed of light. It is losing order.
Entropy and information are maximized in our universe. Life is filled with information.
Lastly you are arguing about both closed and open system. In closed system the rules apply, in open system life can steal energy from other, more vigorous, order destroying mechanisms.
“Order” is the term used by physics. Complexity isn’t a very good descriptor, because lots of things are complex. Both a deck of cards spilled on the floor and a strand of DNA could be called “complex” but one would represent order, and the other disorder.
“What is the amount of order being destroyed, and by what mechanism?”
The amount can be defined by the energy produced by the specific reaction. Electron volt (symbol eV) is a unit of energy equal to approximately 1.602×10−19 joules. That is our best measure and crosses the line between energy and matter. Our various formulas like E=MC2 or E=1/2 MV2 describe the mechanisms.
billbedford – you’ve hit on the one little quibble I have with this otherwise very interesting view of energy flows. Nuclear energy, both fission and fusion, comes from the differences in binding energy per nucleon of different nuclei. (Your starting point for the details would be https://en.wikipedia.org/wiki/Nuclear_binding_energy ) There’s a ‘curve of binding energy’ that shows that iron actually has the most stable nucleus. Fusing the nuclei of elemants lighter than iron releases energy, and spliting the nuclei of elements heavier than iron can release energy.
So Geo’s statement needs a little clarification; it’s ‘a great big ball of atoms lighter than iron’. I don’t think anyone’s ever suggested trying to fission any nuclei of lead or anything lighter for energy. Uranium and plutonium let us set up a self sustaining process because their fissioning also releases neutrons, which is why we can build reactors at all.
Ach! I should have said lighter than iron. And that is a terrific point.
As the atoms being fused get heavier, fusion goes faster. Once the core of a star goes to iron, fusion gets so fast the star explodes. And fusion for some atoms is endothermic.
But yes, that is certainly a deficiency to what I said. perhaps a better way to say it – how pure does the hydrogen being fused needs to be? Does it matter is other atoms are mixed in? Up to a point – no. Stars are not picky.
This is misleading. Building new elements and isotopes in stars is largely addition of H or He to a nuclear core. Many of these proton-in or alpha-in nuclear reactions have characterized required energy levels determined by nuclear chemistry. If they occurred at low energies (equivalent to lower temperature in stars) than small stars like out Sun would do them. Rather, it requires ever increasing temperature in ever hotter stars to build the main trend of elements up from He to Fe. These increasing nuclear cores are modified, building new isotopes, by proton addition reactions (the s process).
Perhaps some more explanation of my comment above.
Bringing together any two nuclei containing protons must overcome a nuclear-Coulomb barrier to that merger. As nuclei get more massive, this barrier is higher, and more energy (equivalent to higher kinetic temperature) is required to accomplish it.
The easiest fusion process is between deuterium and tritium (isotopes of hydrogen with one proton each) and can be accomplished with less than 200 kilovolts. The reason it is so easy is that the quantum field of these nuclei extends as far out as the charge field. So the quantum combination of these nuclei exerts an attractive influence as soon as the charge exerts repulsion.
That said, the energy required to accomplish a fusion reaction is not the same as the net energy contained in the nuclei before versus after fusion. The first is typically much greater than the second.
I just realized, here we are trying to find a “simple” explanation for fusion!
Let me get this right. Small stars fuse to helium and stop. Bigger stars fuse carbon to oxygen. The biggest stars fuse everything down to iron. Since fusing iron is endothermic, the star cannot prevent collapse and a supernova, which generates the remaining elements.
To Geo:
Huge amounts of energy are required to make a small amount of matter. The conversion factor is light — c^2 — a very large number.
I think you are over-emphasizing the entropy change, as it does not figure in every process.
Take fission, which produces two smaller nuclei, two or three neutrons, and gamma emission. Then those fission product nuclei are neutron-rich and decay, usually by beta emission, to stable nuclei. This process produces smaller nuclei, less complex than the original fissioned nucleus, free neutrons, electrons, gammas. This occurs spontaneously (in some nuclei) because the summed internal energy state of the fission products is less than that of the original nucleus. All reactions, whether nuclear or chemical strive toward lower energy states. Many have energy barriers to overcome first, often requiring energy input. It is like bicycling hard up a small hill in order to coast down a much higher hill on the other side.
What drives fusion is understood. It is the tendency for nuclear states to find lower energy values. (The lowest is about Fe.) The issue in going to a lower energy state (nuclear or chemical) is what energy barrier (i.e. input energy) must be overcome in order to achieve this transition. Nuclides that fission strive to become multiple smaller entities.
What drives fusion is also understood. Nuclides that fusion strive to merge nuclear particles to become heavier. Both processes are moving toward Fe with a lower internal state, and both processes give up energy in doing so. It is the energy barriers to these two processes that greatly differ. A nucleus of U has many positively charged protons that repel. It is ready to come apart with little energy input. A H nucleus has no internal repulsion. But to cause it to fuse, two nuclei must be brought close together against repulsion of their respective protons. That becomes a quite large energy barrier. So fusion requires very high temperature (kinetic energy) to proceed.
Fission and fusion are at two ends of a common nuclear (not atomic) energy scale, and they meet in the middle of the periodic table.
Fission, a characteristic of heavy nuclides and elements, releases energy spontaneously because their nucleus contains excess energy compared to their fission products. Many heavy nuclides that seem not to fission, actually do. But the half-life for this fission is much longer than for e.g., alpha decay. Other nuclides that do not spontaneously fission can be prodded to do so with a modest energy input, e.g. absorption of a neutron. But as the nuclide (and element) gets lighter it becomes harder and harder to prod the nucleus to convert into one or more lighter nuclei and give up energy. The end point of this loss of excess internal energy occurs at about the iron nucleus.
Fusion is the above process in reverse but still oriented toward the middle. Nuclides heavier than hydrogen have excess nuclear energy per nucleon than nuclides formed during fusion, e,g, helium. Thus, in converting H to He this extra energy is released. Massive stars use this to produce energy to shine and to make heavier elements. Unlike spontaneous fission, however, a lot of energy prodding is required to make the fusion process occur, even though it releases more energy than was input. As fusion produces heavier and heavier nuclides and elements (e.g., O, Ne, Mg, Si, S, etc., by fusion with He) ever more energy prodding is needed, and ever more massive (and hotter) stars are required. Again, this energy movement ends at about iron. Iron has the most binding energy per nucleon of all elements, and a lot of prodding is needed to move it up or down the nuclear mass column.
You ask how elements heavier than Fe are synthesized? That requires an extremely energetic environment that is capable of working against this tendency for elements to move toward higher binding energy – namely a super-nova explosion.
‘..we may never master controlled fusion? ‘
Project Pacer was a 1970s proposal for controlled fusion that, for once, was clearly within the bounds of current technology. We already know how to make nuclei fuse – heat them up with a fission trigger. Pacer would have used a tiny fission bomb of U233, imploded with lasers or a particle beam, to pour heat and neutrons into a small lithium-deuterium bomb. That would explode in an underground cavern, probably in a salt dome, lined with steel, half full of molten salt, and with salt flowing down the walls to absorb the heat of the blast. Hot salt would be piped to a steam or gas turbine on the surface. Thorium dissolved in the salt would absorb neutrons, and breed enough U233 to keep making the detonators. Since various types of pure fission reactor are easier to build and easier to permit, and there is presently no shortage of uranium, we can leave that one for the great-grandchildren to monkey with.
I suggest you read http://entropylaw.com because an increase in entropy is represented by the tendency for unbalanced energy potentials to dissipate. Energy does not always have to be used up in the process: it can be merely redistributed. In my paper “Planetary Core and Surface Temperatures” first published in 2013 I discuss how the process of maximum entropy production allows us to understand how gravity forms a stable equilibrium (non-zero) temperature gradient in a planet’s troposphere, and this then allows a heat transfer from cold to hot which I have called “heat creep”and which is a major discovery because it completely refutes the radiative forcing greenhouse conjecture. See http://ssrn.com/author=2627605
Someone may have already addressed this, but the following is incorrect:
“This statement leads to confusion – our everyday experience with reality shows entropy being reversed. For example, solar energy hits the leaf of a tree, and is used to create complex carbohydrates. Using lower order energy to create greater order in the carbohydrates of a leaf seemingly violates the laws of thermodynamics.”
Why? Because sunlight is both high energy and low entropy. Your assumption that it is “lower order energy” is where you are in error.
“What then is that precious something contained in our food which keeps us from death? That is easily answered. Every process, event, happening – call it what you will; in a word, everything that is going on in Nature means an increase of the entropy of the part of the world where it is going on. Thus a living organism continually increases its entropy – or, as you may say, produces positive entropy – and thus tends to approach the dangerous state of maximum entropy, which is death. It can only keep aloof from it, i.e. alive, by continually drawing from its environment negative entropy – which is something very positive as we shall immediately see. What an organism feeds upon is negative entropy. Or, to put it less paradoxically, the essential thing in metabolism is that the organism succeeds in freeing itself from all the entropy it cannot help producing while alive.”
― Erwin Schrödinger, What is Life? ”
And from another passage, he writes. “(These, of course, have their most powerful supply of ‘negative entropy’ in the sunlight.)”
Photosynthesis is the process that converts the high energy low entropy photons from the sun into nutrition for themselves and higher life forms, thereby making life on earth possible.
Massive amounts of entropy were generated to produce the light that arrives here, and without which we wouldn’t be here.