Consciousness revisited

What is conscience? Some thoughts in light of recent LLM-inspired debates.

Every human reading this text is conscious.
Every machine reading this text lacks consciousness, and alway will.
These are my starting points and also my ending points.
Much ink has been spilt on this topic. I hereby add my own. With the arrival of LLMs we are faced again with the Turing test, but we’ve got it wrong. The test is not about how good a machine must be to fool a human, but it’s about how bad it can be, and still fool a human. It’s really a test about human psychology, not about computers.
And once we realise this, we also realise that we are all too ready to impute sentience to machines.
I will now consider my two Beagle dogs. They behave very differently, and I’ll omit the details. Trust me on this one. I interact with them as one consciousness to another, and I have no reason to doubt that they are indeed conscious. I take it as a fact. The fact that these two dogs have such distinctive behaviours can only meaningfully be explained by saying they experience the world differently. When Lavendel looks at me she feels compelled to come to me for a pat on the head. Lucy just looks at me and stays. Think about that.

The hard AI position says that everything can be computed, that consciousness, even the world, is just a computation.
I see no reason to accept that statement. All computation relies on modelling and representation: the model is NOT the object it models. This is also true of mathematics. Numbers are abstractions, and boy are they amazing tools for describing the world. Their unnatural nature sometimes reveals itself, in such concepts as infinity and the sums of infinite series. These phenomena are entirely counterintuitive to us, and my take is that these are artefacts that happen to be an intrinsic part of the abstraction. As an example, 1/3 is well defined: divide something into three equal parts. Written in decimal, we get 0.33333 etc, but if we were to choose 3 (not 10) as he base, 1/3 would be written “0.1”, and that would be it. What would Pi look like in base 3? 10.0102… etc. Pi is the ratio between physical properties of a circle. It’s a property of the world, and exists independently of our attempts to describe it. Key point: mathematics is not the world, either; it’s a modelling language.

We can put numbers into a computer and compute, but the output is still within the same category of things, within the same ontology. Numbers, or their decoded formats, like images, sound, text (LLMs treat numbers, not words).

What about humans? We are different, because we are in the world. We are part of the world, and our brains are also part of it. Our brains don’t run a simulation of the world. Yes, our ears and eyes and peripheral nervous system act as transducers that convert one physical signal into electrochemical signals sent to the brain, so the brain only senses the world indirectly. But crucially, the brain does not execute a program. It is the “program”. The word “program” is already misleading us, because it presupposes a distinction between hardware and software. The brain is much more akin to an analogue computer. Analogue computers have also been made by humans ( all digital computers are strictly speaking analogue computers that we restrict to operate in a digital fashion : we run a digital computer on an analogue platform, and run a software program on top of that).

Our neurons respond to incoming signals and send out transformed signals. A computer can model the biological process via a mathematical abstraction, with two fundamental buts:
– the abstraction and the physical object are logically distinct and categorically distinct – they belong to different realms with entirely different properties
– we cannot know that the model is “correct”

There is every reason to assume that consciousness arose through evolution and is linked to brain activity in mammals. There is zero reason to assume that this is in any way similar to mathematically modeled states in a digital computer. Consider if the human-made computer were analogue, consisting of transistors acting in a linear mode with millions and millions of interconnections in a brain-like layered architecture, like a neural network. Would we expect it to be conscious, this huge mass of transistors? No, of course not. So why impute consciousness to a computer program? To do so is a very very strong claim.

A computer takes a model as input and outputs a new model. This model must be interpreted by someone, by a consciousness, or else it remains a model, an abstraction, a representation.
Consider a computer the produces a drawing of a flower on a screen. Now consider that this screen is “observed” by another computer or a human. Where does meaning arise? It’s evident that the seeing computer can only transform the “visual” representation on the screen into some other state – simple or complex. It could output an audible “beep” upon detecting a flower, or do something else. But the human has a conscious experience, and an emotional one, too. Radically different phenomena are at play.


Summing up: the computer operates on a mathematical model of the world, a representation. Your brain and mine are in the world, wired directly into it and obeying the laws of physics (and chemistry!).

Introduction to nuclear energy

What I want to convey.

  • nuclear is strategic
  • nuclear is well understood and safe if treated right
  • how nuclear works
  • nuclear produces waste
  • the waste is difficult to handle
  • nuclear is heavily regulated
  • decommissioning

Nuclear energy is strategic because the investments are enormous, competence is scarce, and the sale of enriched uranium is regulated by the nuclear powers and international treaties. This means that state actors are involved, both in building and funding and running reactors. The number of state actors is limited, and China and Russia, the US and France and Canada are the most prominent. Uranium is found in a small number of countries. Recent data show Australia, Kazakstan, Canada, as the main sources of uranium ore.

Strategic : enrichment, fuel assemblies, source for uranium, waste management and reprocessing

https://www.enec.gov.ae/discover/how-nuclear-energy-works/

The physics and chemistry involved in the nuclear industry are well understood, as are the risks. This is true for current technologies. Pressurised water reactors using light water (normal water) and low-enriched uranium are the most commonly deployed among the about 400 reactors in operation in the world today.  This site keeps an updated tally:

https://www.worldnuclearreport.org/

The safety of nuclear depends on a functioning society. The reactor needs a stable political environment so that it does not get physically attacked. It needs qualified personnel, supply of electric power for cooling from the grid when it’s shut down, access to spare parts, and constant maintenance in order to contain the risks involved. A key element is the need for cooling. Fukushima was a loss-of-coolant accident (Chernobyl was not). At Fukushima the reactor was shut down when the earthquake struck, and the situation was under control. At shutdown, the core continues to produce heat at about 6% of previous power level, decaying rapidly. For a 3GW thermal reactor 6% would be 200MW, and all this heat must be taken away by pumps and heat exchangers. At Fukushima, the cooling was knocked out by the waves arriving some 45 minutes later. By this time, decay heat was way lower, but without adequate cooling, heat accumulated and the core melted, quite simply. At high temperatures the water reacts with the Zirconium cladding of the fuel rods and releases hydrogen which can accumulate and explode, as indeed it did at Fukushima.

This is how a PWR works:

The fuel is uranium dioxide. Uranium is a metal, and so it can “rust” like Iron, and form a dioxide. This is pressed into pellets. The uranium is “enriched”, which means that the content of U235 has been raised from nature’s 0,7% to about 5% by an expensive process called – enrichment (you’ve heard about Iran’s centrifuges). The rest is U238. U235 is an alpha-emitter, so you can carry a new, unused fuel rod in your gloved hand, no problem. The fuel rods are then loaded into the core and control rods are removed and a neutron source is introduced. This starts the chain reaction, and soon an enormous amounts of neutrons are filling the reactor. When a neutron hits a Uranium-235 nucleus this can split and emit more neutrons. The neutrons are high energy (fast) when they are emitted, and strangely this means they are unlikely to cause fission. When they travel through the water coolant in the reactor they slow down (are moderated) by collisions with Hydrogen-atoms in the water, and at reduced speed they are far more likely to cause fission. The water is “normal” water – “light water”. Some reactors use heavy water which is an even better moderator, since it absorbs fewer neutrons; we say it has better neutron economy (water does two things: absorb (eat) neutrons, and slow them down. Heavy water hardly absorbs any, and so a reactor can run on unenriched uranium).

The heat from fission (same process as a nuclear bomb..) is carried away by enormous amounts of circulating water at about 300 degrees and hundreds of bar of pressure, and the heat produces steam to drive a generator. Incidentally 300 degrees is far less than what is ideal as waste heat for industrial processes, and also contributes to poor thermal efficiency. Britain’s Magnox-design uses CO2 for cooling at 700 degrees, and has better efficiency for this reason.

Over a year or two of operation fission products accumulate in the fuel rods. Among these we find some nasty characters like Cesium-137 and Strontium-90 with half-lives in tens of years (31 for C-137) and high levels of deadly gamma-radiation. We also find Plutonium-239, which is fissile and bomb material, and Plutonium-240 which is a neutron source and difficult to handle (it can set off a chain reaction). So the fuel rods are now deadly and also give off heat for a year or two. The longer the rods stay in the reactor, the more Pu-240 they contain, and the less suited they are for extraction of bomb-material Pu-239. Chernobyl’s RBMK was partly designed to allow for a fast cycle (weeks) in order to produce bomb material. After a year or two the accumulated fission products in the fuel rods slow down the reaction by absorbing neutrons and ruining the neutron economy, and it’s time to refuel; the reactor is then offline for refuelling and maintenance.

The spent fuel rods are taken out in lead “coffins” or similar and placed in water pools. A few metres of water stop all radiation, and so there is no immediate danger when they are so protected. After cooling off, they can be stored in steel tanks while waiting for the permanent solution, see below.

To process the spent fuel it is possible to dissolve the fuel in nitric acid – since they are metals – and then separate U from Pu etc, see PUREX on Wikipedia. This is highly specialized and expensive and only a few plants exist in the world. Hence most spent fuel, still containing lots of U235, is sitting around in storage, mainly on the plant sites where they can be guarded. As the French have shown, you can take the reprocessed fuel and mix it with fresh UO2 to create MOX – mixed oxide fuel- to get more energy out of the spent fuel. This can only be done once, since the chemical refining process is not precise enough, leading to build up of unwanted elements – neutron poisons that are hard to eliminate chemically.

Everything nuclear is heavily regulated by the IAEA and the OECD NEA. This keeps risks under control and incurs a significant administrative overhead. The IAEA employs about 2500 people and is headquartered in Wien.

Decommisioning
The hard part of decom is finding a “permanent” repository. Finland is tantalizingly close, this article is very good, and underscores that societal acceptance is alpha et omega.
https://www.science.org/content/article/finland-built-tomb-store-nuclear-waste-can-it-survive-100000-years

Decommissioning itself is essentially about removing the spent fuel, and then tearing down the building. Medium level and low level waste, such as tubes and components that have become radioactive while in service in the plant, must be handled. Facilities must be built to clean and divide and sort these pieces and then package them for long-term storage (50-100 years?) and final repositories (100.000 years). These facilities are themselves nuclear facilities and subject to strict regulations, e.g., by the Norwegian DSA. https://dsa.no/en

Further reading: this article on the CANDU design covers a lot of the physics of reactors – in a readable format. https://en.wikipedia.org/wiki/CANDU_reactor

See also Sabine’s video: https://www.youtube.com/watch?v=aDUvCLAp0uU
I think she may be missing an important point which is made in the Science- article above: you need society’s acceptance for waste disposal. And it’s costly, very costly, and therefore the State tends to pick up the bill. The state will also be the insurer if things go really badly. Fukushima, Chernobyl. The bills and time spans are way beyond what private capital can handle.

There are lots of videos on reprocessing of fuel on Youtube. They often leave out that the residual waste, which is generally vitrified, contains all the nasty gamma-emitters mentioned above. C-137 with its 31-year half life takes 300 years, ten half-lives, for a 2*10 reduction in activity, that is to one thousandth of its activity. By my back-of-envelope calculations, this means: when the fuel is just out of the reactor, it kills you in a few minutes (deadly dose of 3-4 sV). After 300 years, it would take 1000 minutes of exposure, or 16 hours. So much safer!