Thursday, 19 December 2013

Climate science has not failed

There has been a lot of fuss about an apparent difference between the temperature record for the past decade or so and the predictions of climate change models.  Most of what has been said shows little understanding of how models work, or what the meaning of an apparent difference really is.

Computer models of something like climate can never be perfectly accurate because climate is a chaotic and complex result of so many factors.  The way predictions are made is to run models to get a statistical ensemble - a large number of predictions that allow some degree of statistical confidence, and that also help to tell us which factors are significant in causing climate change.

Models will be run which deal with different aspects of climate.  Some will deal with sea temperatures, some air temperatures, some will look at rainfall and so on.  It is really important to understand this, because it shows that what appears to be a difference between reality and the predictions of models of one aspect of climate does not by any means indicate that the science of climate change modelling is flawed.  

Models will be run to answer different questions.  Some will be run to see how much human activity is resulting in global warming and others will be run to see where that warming happens.  This is important to understand because a lack of accuracy in a prediction about where the warming happens does not by any means indicate a lack of accuracy in predicting the overall amount of warming.

Models will be run over different time scales.  Some models are run to help find the parameters which fit past climate measurements so as to provide information to built and run models which can be useful in prediction.  Other models will be run to predict short term climate changes, others will be run to predict long term climate changes.  That some models may not fit well one time scale does not mean that other models won't fit a different time scale.

Of course not all the models will work with the desired accuracy - that is part of the science of modelling, in which development of modelling techniques is always ongoing, but a lack of accuracy in one area doesn't mean abandoning modelling, or rejecting all predictions.

Global warming has not stopped.  There has been a puzzle about where some of the heat energy has gone in recent years, but that puzzle has been solved, and with worrying consequences.  The heat energy has gone more into the depths of the seas than expected, and more into the Arctic than expected.  Extra warming in the Arctic will cause greater ice loss and more potential for feedback systems.  Extra warming in the deep seas will result in a greater tendency for areas of the sea to become oxygen-free, resulting in the growth there of microbes that produce toxic sulphur compounds.

Climate modelling has not failed; warming has not stopped, and the danger is real

Friday, 13 December 2013

There are many Quantum Interpretations!

Quantum Mechanics is strange, and we don't really have any idea of why it is as it is. We see particles apparently communicating infinitely fast to produce apparently random yet coordinated outcomes. We can predict with amazing accuracy the probabilities of outcomes and yet it seems that no-one can predict precisely what will happen. This mystery has led to a range of models of what is actually happening with quantum states, and there are more than just the two models that are widely known: Copenhagen and Many Worlds, but I'll start with those.

The “Copenhagen” interpretation of Quantum Mechanics says that quantum states remain undecided until some kind of measurement takes place, and at that time of measurement the state collapses into one of the possible outcomes. The mystery with this interpretation is that no-one can say what “measurement” actually means. It could be the interaction of the quantum state with some laboratory equipment, or it could be as soon as there is an interaction with a single atom or particle. This interpretation has led to vast amounts of nonsense about “observer effects”, in which the mind is supposed to have some role, but that's not a sensible view of things – the human mind is a physical system which is no more special than any other physical system when it comes to interaction with quantum states.

The “Many Worlds” interpretation says that quantum states don't collapse, because all the possible outcomes always happen. We don't see all those possible outcomes because we are physical systems like any other, and our existence is split when we encounter an quantum state so that there is one of us seeing each possibility. This interpretation is widely used in physics, but I find it unhelpful, as it doesn't answer the question of why THIS copy of me sees what I see – each copy of me will be unable to predict which of the outcomes it sees.

Now, some other ideas:

The “Transactional” interpretation says that as soon as a quantum state interacts with anything at all, an interaction (“transaction”) back and forth through time occurs during which one of the possible outcomes is picked (at random). The link through time avoids the issue of instant communication through space. There is no need for any idea of “measurement”, and there is no “interaction at a distance”.

Roger Penrose's quantum gravity interpretation says that quantum states can remain undecided only while they are below the level at which there is a significant difference in the gravitational effect of possible outcomes. Once that level has been reached the quantum system is forced to collapse into a single state.

I could go on and on. The point is that there are many more ways of looking at quantum mechanics. It's more than just a matter of either “observer effects” or “quantum worlds”. Right now, we have no way to determine by experiment which of these interpretations is correct, so anyone drawing any conclusions from a particular view of quantum mechanics is on dodgy ground!

Thursday, 12 December 2013

Pribble quits - but from what?

I noticed this Slate article, and it inspired me to respond, because I think it contains some significant misunderstandings about on-line communities:

I have to admit I am confused about what "on-line atheism community" is supposed to mean.  I don't see any community structure, indeed I see diverse groups with dramatically different opinions and strategies.  But going by what Martin Pribble implies - that there is an atheist approach of 'debating theists who make a ludicrous claim', then there is a simple way to avoid such debates which is to simply avoid such debates!  There is no necessary 'debating-theist' aspect to whatever 'on-line' atheism is.  There's nothing at all necessary about atheism except for not believing in gods, which is why I find it irritating when I come across phrases like 'atheists want..' or 'atheists believe...'.

But, I believe there is something important about being on-line and atheist, which is to be as visible and atheist while being purely and simply yourself.  Visibility is important, because the world will be a better place when atheism is universally considered to be a part of normal life, and that acceptance comes from familiarity.

There need be no general community and there need be no debating, but what there really does need to be is simple visibility.

Sunday, 8 December 2013

Why religion can be harmful

There are billions of believers, people who think that the world has a spiritual, supernatural aspect, and some kind of all-powerful being or beings created the world and have given us instructions about how to live.  That's the simple fact of theistic religious belief, a fact that cannot be hand-waved away with arguments about theological subtleties or politically correct insistence that we should respect different cultures.  Billions believe that the world is more than it appears to be and that the human mind is able to reach beyond the natural world.

Modern science and philosophy should leave us in no doubt that this is a mistake.   We humans have no such special supernatural abilities, and the world is a vastly larger and more complex place than was ever suggested by religious traditions.  In just about every way in which theistic religions say what the world should be they get it wildly wrong.

Now, it may be that for the majority of people religious belief is relatively harmless, providing some sort of comfort and structure to their lives, but that fact should not lead us to think that religious belief is itself innocuous.  Religious belief is factually a failed way to try to understand the world, yet in most of our societies religious belief is considered a virtue.  That's the problem, and that's how the harm from religion arises.  Religious belief is thinking without a seat-belt - the majority may drive religion safely, but all it takes is a minority to go crazy and people get harmed and even killed.

While there has to be freedom of thought, religion needs to be recognised as potentially harmful, a drug trip that can go badly wrong for some who indulge.