Saturn skydive
Should I go rock climbing on the 6 kilometre peak of Saturn’s moon Mimas (20/27 December 2014, p 58), I think I’ll avoid the temptation to “simply leap off the top and float down to the surface”, as Rebecca Boyle suggests.
Even though Mimas has only about half a per cent of Earth’s gravity, a 6 km fall would be more than enough space in which to reach lethal velocity.
Assuming a vertical drop, my descent would take a little over 7 minutes, plenty of time to take a last look at my surroundings before slamming into the crater floor at 98 kph.
Sheffield, UK
For the record
鈥� We had our wires crossed in the article on self-heating fabrics (3 January, p 15). It is a current 鈥� not a voltage 鈥� that is run through the cloth.
Too much ear wax?
We’ve docked 10 points from ourselves; we should have said “the ability to hear sounds of a pitch higher than any known animal can make”, which is a quality of the greater wax moth, but not Neanderthals.
Too much ear wax?
I have, on occasion, accused friends, family and colleagues of having “selective hearing”, but never to the degree attributed to Neanderthals in your Christmas quiz (20/27 December 2014, p 89).
You write that “there’s no evidence they could hear sounds that no known animal can make.” How sad that they never heard the roar of the ocean, or a clap of thunder.
Nehalem, Oregon, US
Alien DNA
Christopher Kemp’s article on Maxim Makukov and Vladmir shCherbak’s theories suggested that there are patterns in DNA’s genetic code that could not have arisen randomly and so must have been planted there by alien life designers (20/27 December 2014, p 61). But DNA didn’t just arise by random processes.
Although we don’t know how, we surmise that the genetic code must have evolved from earlier self-replicating molecules.
Perhaps precursors of DNA and the genetic code had self-replicatory properties but with fewer bases than four, fewer amino acids, or duplets instead of triplets.
The patterns we see may be the algorithmic fingerprint of that evolutionary process. However, if we fail to find plausible routes to support the idea that the code evolved, it would strengthen the alien code hypothesis.
Blockley, Gloucestershire, UK
Domestic life
We may have. Anthropologists convened last year to discuss the idea that many features of modern humans can be attributed to a process of self-domestication, see: .
Domestic life
From Keith Bremner,
Tecumseh Fitch states that the brains of domesticated animals become smaller than those of their wild cousins (3 January, p 24).
In your Christmas quiz, you wrote that “Humans 10,000 years ago had brains that were 15 per cent larger than ours” (20/27 December 2014, p 89).
Does this mean that we may have lost 15 per of our brains by domesticating ourselves?
Forest Lake, Queensland, Australia
Dangerous doses
In considering the possible health hazards of radioactive isotopes, it may be critically important to take into account the chemistry of the molecule in which the isotope is incorporated.
John Evans (3 January, p 55) reminds us that tritium is as explosive as hydrogen, and Harvey Rutt (20/27 December 2014, p 43) may have been happy to flush tritiated water out of the body with a few beers. But tritiated thymidine, which has been widely used in biological research, is incorporated into the nuclei of dividing cells and may persist in a location where it is most likely to be harmful.
Your correspondents rightly say tritium is not to be treated lightly.
Edinburgh, UK
Counter conspiracy
I have a game I like to play with those who believe in conspiracy theories (20/27 December 2014, p 36). The basic idea is that believers in one conspiracy tend to believe in others as well. You can point out the contradictions simply by running two conspiracies together, and asking them how they make sense of that.
Many of those who think the Apollo moon landings were faked also believe that in 1947, an alien spacecraft capable of crossing light years of space crashed at Roswell, New Mexico and is in the hands of the US government.
But surely if the government has access to such powerful, advanced technology, then taking a few men across to a little rock that is just a hop, skip and jump away would be mere child’s play by comparison? The Roswell crash and faked Apollo missions can’t both be true.
But then, that is precisely what the government would want you to believe, isn’t it?
Dinsdale, Hamilton, New Zealand
Why we yawn
Simon Thompson’s claim that yawning is associated with brain warming seems to be pure speculation (20/27 December 2014, p 38). When offered a hot towel during flying, I always applied it to my forehead, but it never made me start to yawn.
Applying moderate heat or cold to the head is unlikely to alter brain temperature as the organ is not only protected by our thick skull, but by three membranes and cerebrospinal fluid.
In addition, the scalp’s blood supply and that of the brain are almost entirely separate, so measuring the temperature of the top of the head is no guide to that of the brain.
When performing surgery on the brain we used to have to chill the whole body to reduce the brain temperature. It would have been much simpler and safer to have cooled just the head, if that were possible.
Likewise, I never observed a conscious patient yawn during thermo-coagulation for treatment of Parkinson’s disease, where brain tissue is heated with a needle electrode. Nor am I aware that patients with sunstroke start yawning.
Contagious yawning probably occurs through the action of our so called mirror neurones. Did so much unfounded speculation make me yawn? No 鈥� it made me write this rebuttal!
Thicket Grove, Berkshire, UK
Hunger games
I enjoyed Brian Wansink’s article describing how environmental tweaks can influence what is eaten, and in what amounts (10 January, p 36).
So I was disappointed that he did not cite the work of Stanley Schachter and his colleagues, who reached similar conclusions in their 1960s research.
Schachter remains a hero of mine because of the sense of fun evident in all his writings, and his genius for making simple observations carrying profound implications.
For example 鈥� how hungry did Jewish worshippers on fast days feel in the synagogue compared with when they stayed at home; and how was hunger influenced by clock time rather than the actual time elapsed since the previous meal.
Stockport, UK
Scientific language
Curtis Abraham’s article on the importance of science to developing countries could also have mentioned the importance of English as the lingua franca of science (3 January, p 22).
In Thailand, where I live, very few academics and almost no students can read English, and this isolates them from developments in science outside their own country.
A few years ago a Bangkok academic attracted ridicule when he said that melting glaciers would not cause sea level rise in Thailand because there were no glaciers in Thailand. Greater promotion of fluency in a common language is an essential element of promoting science in developing countries.
Jomtien, Thailand
Not quite everything
The Theory of Everything is a well-acted biography of Stephen Hawking, which portrays scientists in a more realistic light than most films manage to do (3 January, p 40).
However, it severely minimises and distorts the role of Dennis Sciama, Hawking’s doctoral supervisor. Sciama is portrayed as a cartoon character, a kind of authoritarian gatekeeper who gradually develops affection for Hawking as he begins to regard him as a colleague.
Sciama was much more than that picture suggests, he was a superb mentor who brought out the best in his students. After Hawking’s diagnosis when he spent some time depressed, Sciama said to him, “Well, you’re not dead yet. So, are you ready to work on that problem I suggested?” The rest, as they say, is history.
It’s my belief that Hawking’s history could not have been the same without Sciama’s constant interaction and feedback. I wish that his legacy had been strengthened by the film.
Lawrence, Kansas, US
Space farming
Michael Slezak writes that plants grown in space will need the soils we bring with us (20/27 December 2014, p 6). But why? In the Mars mission study programme in the early 1980s, NASA established that soil-less aeroponics was the best way to grow crops in space 鈥� mainly because it made large weight savings possible.
Bapchild, Kent, UK
Dark quantums
It’s a great question, and one we don’t know the answer to yet.
Dark quantums
I was pleasantly surprised by Michael Brooks’s article on quantum gravity (3 January, p 26), and like all good articles it got me thinking. If photons, particles, atoms and so forth can exist in superpositions, interact with themselves and create two gravitational fields, would it not be possible to detect the extra mass?
And if so, what implications does this have in the context of dark matter and dark energy?
Wath-upon-Dearne, South Yorkshire, UK
Lawyers' limits
As a trial lawyer of more than 20 years’ experience, I was interested to read about linguist Alan Yu’s research regarding the effect of a lawyer’s voice on court judgments (3 January, p 12).
However, it seems that Yu has missed one very important factor: the relative merit of each case. We lawyers do, of course, bring something to the table in legal proceedings, but no matter how skilled we are, it is a simple fact that some cases are far less winnable than others.
Given that the US Supreme Court hears appeals on matters already determined, success will rely on showing that the lower court’s decision was infected with error 鈥� or that it wasn’t, if the respondent is to be successful.
Even the most skilful advocate cannot show error where there is none, nor hide errors that are there, no matter what tone of voice he or she uses.
Jury trials are of course quite different, and the best lawyers are skilled people-readers who can alter their tone, manner of speaking and many other variables to suit the jury before whom they are appearing; judges, however, are not so easily manipulated.
Kenmore, Queensland, Australia
Why we yawn
Simon Thompson suggests that people with autism aren’t as prone to contagious yawning as other people are because they can’t recognise facial expressions.
Yawning is not the sort of subtle facial expression that some autistic people may find hard to read. As Thompson writes, studies have shown that contagious yawning is related to how close we feel to the yawner.
It’s much more likely that people with autism don’t show a strong yawn response because they don’t feel an emotional connection to the yawner. Logic is the order of the day for us.
Brighton, UK