Extraterrestrials' intelligence is not a given
Dan Falk writes that a reply from extraterrestrials is “possible” within 25 years (25 November 2017, p 12). But what if human civilisation is one of the most advanced in the galaxy? Look at all the technology we have at our fingertips. Any extraterrestrials we encounter are as likely to live in caves as to be superintelligent.
For the record
• Rats! Tschudi's slender opossum (Marmosops impavidus) is a marsupial (23/30 December 2017, p 26).
Thank you for solving a bright night mystery
Thanks to you, I have solved a mystery. One night last month – sadly I didn't make a note of the date – my husband and I went for an evening walk in the countryside around our north Devon home, where there's very little light pollution.
There was no moon, but the sky was extremely bright and structures cast dramatic shadows. I now assume we experienced a “bright night”: spectacular, and very strange indeed (23/30 December 2017, p 63).
We thought we were having dangerous fun
Clare Wilson writes: “teenagers are in the midst of a mental health crisis” although they “are less likely to take drugs and get drunk than they used to, and teen pregnancies have been falling for many decades” (4 November 2017, p 22). In my teens in the late 60s and early 70s, I took drugs, got drunk and had (or tried to have) as much sex as possible.
That followed an earlier childhood during which I broke legs, sliced myself on glass shards, stabbed myself in the eye with bamboo (requiring major surgery) and blew up many inanimate objects using home-made gunpowder. At the time, I considered I was having fun, and I look back on it as one of the happiest times of my life. Talking to many other men and women of my age, their recollections and feelings are similar. Maybe we are just the ones who survived. Or maybe we, and our parents, knew something that has now been lost.
Even wronger ways to blow up balloons
Collins's letter brought back to me a childhood incident. I was raised in Pembroke Dock, south-west Wales. When I was about 7, electricity came to our road. It brought all manner of new things into our lives, including a cylinder vacuum cleaner.
The fact that the note of its motor changed when the suction inlet was restricted caused me to wonder what sound would be made if something other than air passed into the cleaner. It was simple to detach the rubber hose that fed the gas fire and put the suction pipe of the vacuum cleaner over the gas tap. I switched the cleaner on and then turned the gas tap fully on. The note of the vacuum cleaner did change – just before the explosion.
I never divulged the nature of my experiment and the event was put down to a freak accident connected with this newfangled electricity. The vacuum cleaner was repaired and went on to give well over 30 years of service.
The editor writes:
• Do not try this at home, nor anywhere else.
Even wronger ways to blow up balloons
Brian Collins describes one wrong way to blow up a balloon (Letters, 16 December 2017). In the mid-60s, I felt it right to mark the occasion of our last mess dinner at the Naval Engineering College – all those smart uniforms were too tempting. I filled balloons with talcum powder, glitter, hydrogen from the labs and a bit of Jetex fuse, planning to release one or two in the dining hall.
Luckily, I ran an outdoor test first. The result was a fireball about 3 metres in diameter that lit up the entire valley. The hydrogen flame was evidently hot enough to ignite the aluminium flakes in the glitter. I learned the great value of a full-scale trial!
Ancient Greeks did have the blues
Materials scientist David Dobson seems to be struggling to create a new blue pigment. Why does he not simply make Egyptian blue? Many researchers believe it is calcium copper tetrasilicate, and give syntheses (Journal of Cultural Heritage, ).
Ancient Greeks did have the blues
Joshua Howgego says the ancient Greeks had no word for blue (23/30 December 2017, p 47). But they had many, such as kuaneos (cornflower blue) and glaukos (steel blue-grey). Both words were used by Homer, the poet famed for his “wine-dark sea”.
I believe “Egyptian” blue was lapis lazuli, and it ceased to be used in the Middle Ages not because a recipe was lost, but because scarcity pushed up the price and hence limited its use to the most sacred parts of images, such as the Virgin Mary's robe.
By their quirks shall you know their code
You report using software to analyse people's coding styles (25 November 2017, p 36). I used to manage code written by a dozen or so programmers. I often had occasion to question them about it and found that I could usually identify the author of any section based on a quick glance – and always in the case of one whose comments invariably contained spelling errors.
Editor's pick: Critical thinking on comparative advantage and critical thinking
Graham Lawton asks why we are often misguided, and begins by explaining that international trade is a win-win game because of comparative advantage (16 December 2017, p 28). He explains this in terms of a two-country, two-commodity international economy, just as the economist did in 1817 when he first set out the concept. But his theory involves numerous assumptions, one of which is that capital is immobile between countries.
Freeing flows of capital to seek absolute advantage has been one of the major developments in the global economy over the last two centuries. And comparative advantage doesn't address distributional issues. For some people, international trade is clearly a losing proposition.
So what did make those marks on Phobos?
Discussing various causes for the “linear virgae” on Saturn's moons, Adam Mann mentions grooves on Phobos produced by “rolling boulders” (23/30 December 2017, p 12). This notion was fired by early, low-definition pictures of Mars's moon. Gravity on Phobos's surface is nearly 2000 times less than on Earth. Any boulder hitting the surface hard enough to dent it and start a groove would bounce off again, if it didn't shatter.
More study has found two possible mechanisms for the features seen: on Phobos due to its small orbital radius around Mars, and made by bodies captured by Mars and broken into multiple pieces by the same tidal forces.
The discord which befell, and war in Heaven
The notion of Donald Trump striving to plant another US flag on the moon and subsequently on Mars (16 December 2017, p 6) is surely bad enough without the further ambition of militarisation in the name of US defence. Is it not long overdue for the United Nations to step in and declare that space and bodies therein should forever be strictly neutral, strictly non-national and very strictly non-military?
In defence of humorous medical papers
As well as the BMJ's Christmas edition bringing some much-needed levity at the end of each year, mining the citations is an excellent opportunity to identify researchers who aren't paying attention to detail. It should also give journal editors the chance to dispense with the peer reviewers who aren't paying attention to the work they're vetting.
In defence of humorous medical papers
I was sad to read your article criticising papers in the British Medical Journal's Christmas edition, having just enjoyed reading the papers in question (16 December 2017, p 25). I thought they neatly captured a number of “I've often wondered about that” issues. While the writing style was more quirky than usual, the methodologies seemed robust.
I find it hard to believe that others will seriously misinterpret these papers if they read them before citing them. Their spirit reminds me of Gerald Scarfe saying he aimed for his cartoons to tell the truth in a humorous way. Much like articles in a certain popular science magazine's Christmas edition, they are also very quirky, entertaining and informative.
Editor's pick: Critical thinking on comparative advantage and critical thinking
Lawton says that “around 85 per cent of the world population” are “largely untrained in critical thinking”. I wonder how this statement itself stands up to critical appraisal. Does it relate to the percentage who attended university – assuming that such institutions still find time to teach critical thinking in today's world of corporate education? Are all children taught some degree of critical thinking by their parents or elders as a necessary survival skill?
First class post
But wait, it gets worse: we manipulate events so they're more like a good story
Pawel Pachniewski the finding that our brains make up good stories to fill in perception gaps (16 December 2017, p 28)
Editor's pick: Critical thinking on comparative advantage and critical thinking
Lawton gives a clear worked example of why free trade is win-win. But the conclusion is based on the premise that the players in the game are national states and that the measure of comparative advantage is economic growth. If instead we treat humanity as the only player and define economic growth as the accelerating extraction of wealth from a finite planet, then it is reasonable to believe that, in the long run, we and our descendants are in a zero-sum game after all.