Editor's pick: What information would an artificial physicist produce?
John Pavlus asks whether the success of neural networks leaves anything for human physicists (28 October, p 36). It depends on what you think physicists are trying to do. Experiments carried out using the neural networks he describes are great for telling you how a system is going to work, and potentially for designing new materials. But the only way to have confidence in the results is to test the physical system. A neural network in silicon is just as capable of being misled as are our own carbon-based networks, especially if we fail to provide a piece of relevant information.
The physicist's calling, however, is more than just testing and synthesis. Most of us rate understanding several notches higher. To put physicists out of a job, the neural network needs to explain why it thought the problem was worth solving, which data it regarded as relevant and which irrelevant, what approximations it made, under what conditions the solution is valid, and how the solution fits with the existing corpus of knowledge. Even then, without a human physicist to explain all this to, it all seems a little pointless.
Editor's pick: What information would an artificial physicist produce?
Pavlus states that computers “represent information in ‘bits’ that can only have a value of 1 or 0”. But a bit of information is fundamentally different from a bit of data.
Each binary digit (bit) of data can have a value of 1 or 0, and each value can represent between 0 and infinity bits of information. For those who want detail: if the probability that a data bit equals 1 is P, then the amount of information represented by a 1 is log2(1/P) bits. This value approaches infinity as P approaches zero. It has been to name the unit of information after the inventor of information theory, Claude Shannon.
First class post
At this point in the movie, we get that feeling things won’t end well for the humanoids Whimsy (aka Shirin) that if driverless cars can save lives, so can armed machines (11 November, p 22)
Body cameras assist both police and public
Alice Klein asks whether body cameras are working to defuse tense situations (21 October, p 22). The evidence seems clear that body cams do make a significant difference in reducing citizens' complaints and violence against police officers.
Police forces thus have a clear duty of care to both their officers and citizens. How long will it be before forces are prosecuted for not giving officers what should now be basic protective kit?
Body cameras assist both police and public
The finding that police use of force and citizen complaints both declined dramatically after body-worn cameras were deployed reminded me of a study that found men were more likely to wash their hands after using the toilet if there were other men in the room than if they were alone. Observation seems to elicit best behaviour on so many levels.
Body cameras assist both police and public
You write that, “eventually, events not caught on camera could be treated as if they didn't happen, like the proverbial tree falling in the forest” (21 October, p 3). Ask any black man, at least in the US, and they will tell you about being stopped, frisked and harassed – or beaten and imprisoned – by police without cause or due process.
Charges against police of false arrest, perjury, planting evidence, assault and murder are routinely dropped because the court system almost always believes the word of the officer over the word of the black man. Indeed, since prosecutors know what side their bread is buttered on, charges are rarely brought against officers.
To address these issues, body cams worn by police need to always be on except when permission to disable them is explicitly granted by the police dispatcher for reasons that are in the public record. And their footage needs to be publicly accessible so the police can't suppress damning incidents.
Luther's legacy was one of diversity of thought
Martin Luther's legacy was arguably not a scientific revolution based on freedom of thought or on rationalism, but the unintentional opening of the door to diversity of thought (28 October, p 32). Many early strands of Protestantism were highly intolerant of dissent, worse in many cases than the Catholic church. But by placing the Bible rather than the church hierarchy at the centre of truth, Protestants reopened Christianity to a diversity of beliefs – often conflicting with each other.
For the previous millennium, the church hierarchy had tried to put in place a consistent belief system on top of a holy book that is highly inconsistent in both beliefs and narratives. The Reformation made it close to impossible to re-establish conformity and exposed many biblical teachings to direct conflict with the reality of the world.
The scientific revolution may have started independently of the Reformation, but the diversity of thought it unintentionally created allowed it to flourish.
Luther's legacy was one of diversity of thought
Philip Ball's perceptive article on science and the Reformation was most refreshing. In England, particularly, the work of medieval figures such as and , not to mention that of Muslim scholars, demonstrated a real desire to come to a properly scientific, empirical understanding of the world. After all, the theistic vision of the universe as the offspring of a supremely rational creator is, to say the least, wholly consistent with the scientific enterprise.
Luther's legacy was one of diversity of thought
Ball says that Nicolaus Copernicus challenged accepted Earth-centred cosmology, but drew little objection from the church, unlike Galileo later, who he blames for provoking it. It that it was to Copernicus's book that allowed him to avoid strong church reaction.
This presented the new system as a familiar academic exercise in mathematical equivalence, not as reality. And because Copernicus used only perfect circles for orbits, he had to approximate the observed celestial movements by adding exactly the same kind of circles on the circumference of the main circle that the accepted Ptolemaic system used.
The ethics of DNA testers putting genes on sale
Jessica Hamzelou discusses companies that sell DNA tests to consumers almost as a sideline, the real value being in the data they gather (7 October, p 22). This practice is held to be ethical, so long as consumers have given informed consent.
It is argued that the potential health benefits to the public outweigh the potential risks. But should DNA companies offer their customers access to genetic counselling services, so that results can be discussed and responsible education about genetic information delivered? Perhaps they could undertake more partnerships with non-profit research organisations to make sure the benefits of the DNA databanks are a public good, not just a commercial one? They could also reinvest some of their profits into non-profit genetic-based disease research.
Moderate meat eating or suppress methane?
Bob Holmes's summary advice for a healthy and environmentally friendly diet was straightforward and helpful (23 September, p 35). Unfortunately, it mentioned only in passing the contribution to global warming of methane burped by cattle and sheep. Some estimate that these ruminants produce up to 20 per cent of all greenhouse gases emitted globally. Pigs and fowl don't produce methane.
When Mark Nearing concludes that “our only rational course of action” is “moderation in our meat consumption (or its elimination)” he ignores this huge distinction between different kinds of meat (Letters, 21 October).
Furthermore, at James Cook University in Queensland, Australia, is finding that adding the seaweed Asparagopsis taxiformis to make up 2 per cent of ruminants' feed completely inhibits methane production.
Remembering William Penney differently
Readers from Australia may have a different view of the status of William Penney (14 October, p 42). Undoubtedly, he was an excellent practitioner of nuclear physics, but his work included a number of atomic tests at Maralinga in remote South Australia. These left large areas contaminated and caused significant loss of life among the Aboriginal people, as well as rendering some of their land uninhabitable. The supposed clean-up by the UK was poor and the long-term consequences for both the Aboriginal people and service personnel have been, some would say, disastrous.
Remembering William Penney differently
Fred Pearce says the “Penney dreadful” nuclear weapon “required huge amounts of tritium” and suggests this contributed to the 1957 Windscale reactor fire in the UK. But he also notes that though the nuclear test code-named Orange Herald was announced as a fusion weapon, it wasn't. It may have been a “hybrid”, with most of its explosive power coming from fission of uranium and a small amount from fusion of tritium. But in these – and probably in most practical H-bombs – the tritium is mostly generated in situ from lithium.
Now if you're ready, oysters dear…
It is good to know that the tongue-twister “a noisy noise annoys an oyster” is now scientifically proven by the observation that they can “hear”(28 October, p 18).
For the record
• The kinetic energy of an iron asteroid 500 metres across is about a hundred-thousandth the energy Earth receives from the sun in a year (28 October, p 42).
• Mild-mannered journalists note that the proper name of a certain superhero is Spider-Man, with a hyphen (28 October, p 39).