Fall and rise
Along with the downsides of climate variation for ancient civilisations (4 August, p 32), could there have been some upsides? Bigger monuments and new gods for new odds could well be one, as could the demise of shamans too reliant on the previously predictable march of the seasons.
Although not evident in the research cited, other possible impacts of a more variable climate include the need for more trade to survive crop failures, more grain storage, even more cats to eat the mice, and more writing to record the transactions.
There may well be lots of examples of civilisations declining as an impact of climate change, but how about an analysis of civilisations on the upswing, and with some trumpeting of triumph over adversity.
From David Allen
To the list of those wiped out by climate change you can add the Greenland Vikings, who happened to settle there during a warm period but couldn’t survive when the climate became cooler. It takes very little to knock a civilisation off its perch, and a change in climate that affects food production will surely do it.
Fulham, South Australia
From Pat Scott
Your article points out that the mechanisms of climate and climate change occur on a vast scale. What it doesn’t mention is that they can also occur on smaller scales linked to local events and conditions.
One mechanism present in all the civilisations mentioned is that the environmental destruction, deforestation and land clearance associated with increased population can cause drying conditions. A powerful feedback mechanism can result, which exacerbates the drying, bringing on prolonged droughts.
Roleystone, Western Australia
Keeping track
Your look at those who use technology to closely monitor key aspects of their lives, such as health and activity (4 August, p 40), was of interest to me, as my partner is an obsessive self-tracker.
He reasons, quite rightly, that it enables him to identify patterns and thereby deal with problems such as weight gain, sleep deprivation, health issues and work-life balance.
He tracks everything – from his sleep, calorie intake, weight and amount of exercise to the time he spends at work and what he does in his free time.
I have recently asked him to stop recording my orgasms and the number of times we make love, as I became concerned that the tracking was becoming more important than the actual love-making, that the figures would be added to some spreadsheet tracking lifetime sex, and that they would be used in some sort of comparison analysis.
Indeed, his quantifying is taking longer than some of the actual activities; but he seems not to be quantifying the time that he spends quantifying*.
From Mary’s partner, Paul Ellis
*Yes, I do!
London, UK
Reality of maths
In his recent look at the Schrödinger wave function, Marcus Chown states that “most physicists… believe the wave function to be merely a probability distribution” (28 July, p 28), as if this purely mathematical entity were removed from any correspondence to physical reality.
But the equations it underpins seem to work brilliantly, so it seems the wave function is a strong example of the , in which the mathematics itself leads to further insight.
Now, according to the work of Matthew Pusey, Terry Rudolph and Jonathan Barrett mentioned in the article, it is possible to show that a very weird kind of physically real wave function that informs quantum systems how to behave exists in an abstract space.
It is possible they might also have discovered the missing link that solves the unreasonable effectiveness problem, at least as far as the mathematics of quantum systems goes.
Once the problem has been solved for this hardest case, maybe it will prove possible for easier ones.
Avatars on trial
Copyright concerns over digital doppelgängers are one thing (11 August, p 38), but who will people choose to sue when your electronic double issues something defamatory?
You, or the company that enabled the creation of the avatar? Or will it be such a saintly avatar that it avoids this eventuality, and so will never quite manage to be convincingly human?
Tweet store
Further to Feedback’s look at Higgs boson humour (21 July), in which you stated: “We preserve this joke for posterity, since as far as we know no national libraries have Twitter on the shelves.”
You might be interested to know that the has digitally stored Twitter’s archive material.
Free fall contender
In the history of extreme parachuting (21 July, p 36), Charles Bruce is worth a footnote. His book Freefall (Little, Brown, 1998) written under the pseudonym Tom Read, covers his abandoned attempt to be the first to free-fall more than 37 kilometres and to break the sound barrier unassisted.
Sadly, he died in January 2002 in a fall from a light aircraft.
An app for that
Having just returned from a holiday where I had no cellphone or email access, and feeling very relaxed as a result, I read your article on a smartphone that feels your strain (11 August, p 20).
If the constant access to work emails through my phone is stressing me out, maybe this app could let me know and then turn my phone off for me.
Illusion of choice
Your editorial on research that examines whether we have free will understates the paradox (11 August, p 3). It is impossible to live as an automaton even if you believe that free will is an illusion.
The last sentence: “We may not have the ability to choose, but we choose to think we do”, should read: “We may not have the ability to choose, but we are compelled to think we do.”
Handling venom
Your discussion of the use of venoms as drug candidates (5 May, p 34) reminds me of the time I spent in the early 1950s detoxifying cobra venom for a project at the University of Miami that was having some success using it to treat polio. The development of the Salk vaccine for the disease ended that work.
My life-saver
Having had aggressive prostate cancer picked up by yearly screening for prostate specific antigen (PSA), I can speak for the usefulness of this blood test (4 August, p 12).
My prostate was small and had no irregularities. At 59 years of age, I did occasionally have to get up in the night to urinate, but otherwise was symptom-free. My PSA level spiked from the previous year, and a test a month later showed a further moderate increase. A biopsy of my “normal” prostate revealed that I had aggressive cancer.
The lesson is not that there is a particular problem with the test, but rather what is done with it. The debate on PSA testing has moved away from addressing the science of its usefulness to a cost-benefit analysis.
In my view, every man over 50 should have access to an annual test. It should be cheap and routine, and we should let the science decide how and when to use the results to determine the need for intervention.
Curiosity's appeal
We should not be surprised at the global jubilation and interest surrounding the touchdown of NASA’s Mars rover, Curiosity, mentioned in your editorial (11 August, p 3). Could anyone familiar with the incredible sequence of automated manoeuvres programmed into this craft to ensure a safe landing fail to be impressed?
Our anthropomorphic treatment of machines is nothing new, and seems to be growing apace in society. When crowds gathered to witness footage of Curiosity’s arrival on Mars, surely it reflected a sense of shared human achievement mixed with a peculiar sense of pride in and connection to the 1-tonne spacecraft that managed to come through for us all.
Historical units
Feedback’s ongoing discussion of alternative systems of units (4 August) rekindled a memory from the 1950s. While working with physicists at Harwell in Oxfordshire, UK, we decided that both the metre-kilogram-second and centimetre-gram-second systems were rather sterile, lacking both culture and history. So we searched for something more suitable.
The result was the furlong-pennyweight-fortnight system, which had a certain ring to it. We even worked out the velocity of light in furlongs per fortnight which, for your interest, is 1,803,000,000,000.
Seeds of life?
You reported research showing an excess of left-handed amino acids in meteorites found in Canada (4 August, p 17). Surely this could be used as evidence for panspermia, the theory that life on Earth was seeded from space, as proposed by astronomers Fred Hoyle and Chandra Wickramasinghe.
If some process in space produces an excess of these left-handed molecules, which are essential to life, then it would be expected that life, if started in such a way, would have a bias the same way, as it does on Earth.
Armed struggle
Interesting as her analysis of the origins of inequality might be, do the comments by anthropologist Deborah Rogers (28 July, p 38) amount to anything more than an endorsement of 17th-century English political activist Gerrard Winstanley? He stated that: “The power of enclosing land and owning property was brought into creation by the sword.”