Editor's pick: Let's investigate levels of brain structure
Caroline Williams reports work on the pattern of links in the brain – the “connectome” – that finds “holes” in the network (25 March, p 28). But I find the work interesting for other reasons.
First, I should say that the graph theory she describes doesn't care about the arrangement of things in normal space. Like topology, it treats space as stretchy. All that matters in graph theory is the pattern of connections between nodes. So if there are “holes” in the connectome in the everyday sense of physical space that connections skirt around, they're not interesting to graph theory. It is no surprise that the graphs have loops. What is of interest is which neurons connect, or fail to connect, to which.
So I think the most significant implication of this research is that the connectome is organised in a hierarchical manner, with dense local clusters of neurons – “cliques” – connected to other clusters in different parts of the brain. It is possible that there are more than two levels of hierarchy. This should be the subject of further research.
Morn came and went and brought no day
Arguing that talk of a “localised” nuclear conflict is ignorant and dangerous, you refer to “nuclear winter” (22 April, p 5). During the cold war, some people used to carry around the 1816 poem by Lord Byron. It refers to the “year without a summer” that followed the eruption of the volcano Tambora. It tells us that any nuclear winter could have far worse consequences. Maybe we should resume the poem-carrying habit.
Morn came and went and brought no day
Clearly a nuclear exchange in North Korea or anywhere else is to be deplored, but I doubt that “millions of tonnes of smoke would gush into the stratosphere, resulting in a nuclear winter”. There have been more than 500 atmospheric nuclear tests with a total yield in excess of 500,000 kilotons. North Korea’s stock is unlikely to exceed 50 kilotons.
The editor writes:
鈥� A model in which two states each use 50 small (15-kiloton) warheads predicts 5 million tonnes of black carbon from firestorms entering the stratosphere (). Atmospheric tests don’t ignite cities. North Korea doesn’t have an arsenal that big, but both the US and China do.
Article amended on 15 May 2017
We corrected the quantity of black carbon predicted by the model
First class post
Can those who believe in ‘alternative facts’ on climate change find an alternative planet?
Maggie McPherson to deniers who mocked the March for Science on social media (29 April, p 4)
There is good reason to have faith in facts
Graham Lawton laudably aims the searchlight of reason impartially at both atheism and religion (15 April, p 32). It is almost a dogma among certain atheists that the world's atrocities are largely due to religion. In reply, religious apologists single out vicious atheists – and atheists argue these weren't real atheists, but were heavily influenced by the religious beliefs around them.
Time and again, “to the glory of God” was merely the excuse of the politician seeking justification, just as “historical inevitability” became the excuse of many a 20th-century warmonger.
When one chimp group attacks another, it is rarely suggested that religion is involved.
There is good reason to have faith in facts
Lawton mentions counterfactual beliefs being used to motivate behaviour. Anthropologists Pascal Boyer and have studied not only the politically dominant religions, but also cults of ancestral spirits or sacred trees.
In their view, religions have, at their core, a counterintuitive and counterfactual idea that is taken seriously. Santa Claus, magic shows, Pythagoras' theorem, quantum physics and the telephone are counterintuitive ideas and thus fascinating, but those that are taken seriously are not counterfactual.
So the core of religion is worthless. How do shamans and priests stay in business? They dress it up with frills such as a ritual, a creation story or the pretence of being the fountain of goodness. If possible, they punish unbelievers.
There is good reason to have faith in facts
I am sure that most rational unbelievers don't spend much time agonising over their lack of interest in religion. They have better things to do than ask why a blasphemer has to be shot by a mere human. Surely an offended omnipotent being could turn them into a wastepaper bin or a pillar of salt – an effective deterrent, I should think.
There is good reason to have faith in facts
Let us say that atheism is not a religion. Let us say it is a scientific theory. All atheists have to do is come up with some predictions. Then the theory can be tested by practical experiments.
There is good reason to have faith in facts
I am an Everythingist. This is a religion I created for myself many years ago. It really stumps anyone who attempts to convert me, because my belief includes their belief: I am already one of them.
Everythingism believes in “wonder”. It values differences. It is scientific because it is open to learning, to discovering. It is in awe of this thing we are all part of, this “life living itself”. It is not arrogant – there is so much we don't know. It is compassionate, as it includes everyone and everything. It is a religion because I believe in it. Everythingism is all-inclusive and non-exclusive. You can like it or not as you choose.
Distribute carbon tax as a citizens' dividend
Michael Le Page's article on carbon pricing and tariffs was very welcome (8 April, p 22). But an aspect it doesn't cover is the negative effects that carbon pricing could have on poverty and economic growth. One way to counteract, and probably even outweigh, these is to redistribute revenues equally to citizens as a dividend.
This idea has been gaining ground in the US, even among Republican politicians and in spite of Trump's denialist rhetoric. It is promoted by the , an organisation started in the US, but also growing internationally.
Spare not of your free speech to spare my ears
Sally Adee observes that bot accounts sometimes drown out the voices of actual humans on Twitter, “effectively censoring speech without suppressing it” (1 April, p 25). Puzzlingly, she then jumps to a wholehearted defence of government-mandated censorship of “hate speech”.
Wouldn't it make more sense to simply come up with solutions to the bot problem? There are many: introducing time-consuming procedures to certify that the submitter of a post is human; charging a few pennies per post to discourage bots since the expected pay-off per post would be less than the charge; using human moderation; or crowdsourcing the elimination of bots through a “down-vote” mechanism.
The modern problem of “fake news” wouldn't fall into the category of “hate speech” to begin with and so wouldn't be solved by the censorship Adee proposes.
Those who oppose censorship don't “hide behind the old defence of free speech”, as she puts it. They are committed to protecting free speech as one of the freedoms that is core to democracy, is a basic human right and is a freedom that authoritarians everywhere have always worked to undermine.
Are degrees of belief enough knowledge?
You discuss the problems of epistemology (1 April, p 32). Many can be avoided if we take the statement that we know something and replace it with a degree of belief based upon all the available evidence. Degrees of belief can be modelled using probability theory and can be updated as we acquire new evidence using Bayes' theorem. Since your available evidence can be different from mine, our probabilities can be different too.
If I think it is about lunchtime and glance at a clock that says 12, then I will adopt a probability distribution function narrowly peaked around 12 o'clock. If I glance again a short while later and see the clock hasn't moved, I will revert to a much wider distribution of possible times, and infer a high probability that the clock is broken.
Quantum socks are a misplaced analogy
Neither Stuart Clark (4 March, p 28) nor Brian Horton (Letters, 1 April) has demonstrated an understanding of the “weirdness” of quantum entanglement. The essence of some ultimately observable attribute of a quantum particle, such as the “spin” of an electron, is that before it is “measured” or “observed”, it is totally undefined.
It doesn't have a definite value, but exists in a superposition state of every value possible. So the analogy of two differently coloured socks is inapt.
The “sock” representing a particle before “measurement” can't only be any colour, it can be any of the infinite hues of any colour. The weirdness arises because no one understands how the second “unmeasured” entangled particle somehow “knows” the “measured” value of the first particle when there was insufficient time for any signal to pass between them.
The attribute of the second particle is also undefined, supposedly without a definite value, until it is “measured”. Yet somehow when “measured”, it always adopts a value that preserves conservation laws. That is quantum weirdness.
I breathe not thy name
Leah Crane mentions the black hole Sagittarius A* (8 April, p 8). Can we ever say that aloud?
There was no footnote to the article, so, clearly, it's not “A asterisk”. However, “A star” sounds equally wrong. This black hole at the centre of our galaxy swallows many stars, but it's not really a star itself.
There used to be gods, once, so mighty their names could never be mentioned. Perhaps A* is where they retired.