Editor's pick: Moderating meat is our planet's only hope
Bob Holmes's search for “real clean food” – a diet that is both healthy and eco-friendly – was one of the most thoughtful and unbiased, scientifically based articles on the environmental impacts of food choices that I have read in a long time (23 September, p 35). I have spent my career trying to understand and improve the science behind soil erosion, conservation and climate change. It bothers me greatly that so much of the world's greenhouse gas emissions, not to mention soil degradation problems, are related to the intensive rearing of animals for food.
This has been the invisible problem in climate change discussions for too long. Calling for moderation in our meat consumption (or its elimination) and more environmentally friendly production is our only rational course of action if we want a sustainable future for this planet.
Bravo to 快猫短视频 for setting the record straight. As Holmes rightly points out, every individual can make rational food choices for a better world.
Disarmament workers halted counterfeits first
Ida Emilie Steinmark reports on efforts to make a physical version of the “one-way functions” of cryptography, in order to detect counterfeits (30 September, p 33). This was, in fact, preceded by a method devised by US and Russian researchers to help verify adherence to agreements in the 1970s . It was a tamper-proof seal to prevent covert upgrading of warheads. The procedure was simply to glue the access panels shut with transparent epoxy resin, mixed with a pinch of glitter, in a deliberately messy blob. Once cured, the random pattern was photographed under laser illumination.
It was deemed impossible to upgrade a warhead and then recreate the pattern precisely, positioning each speck of glitter and every lump and ripple of the epoxy mass to nanometre accuracy. I wouldn't like to try it.
First class post
The medical opportunities are obvious. Frighteningly weaponisable, though.
Olivier Parisy to using CRISPR to change DNA to treat disorders (7 October, p 8)
Another candidate for the oldest zero sign
I read with interest your report of a claim to have discovered the earliest mention of a symbol for zero, in a previously undated manuscript from India (23 September, p 19). Its oldest pages are now dated to between AD 224 and 383.
This may not be the oldest zero, though. Michael Wright is one of the that was discovered early last century in a shipwreck off the Greek island it is named after. He observed “index marks” on one of its dials. These form a series that, in order to make sense, requires an engraved marking of “zero” in one of the index positions on the dial.
Such a mark is tantalisingly almost apparent, peeking out from some marine encrustation that is, frustratingly, yet to be removed. That may never happen, due to the delicacy of the artefact.
The mechanism is now as early as 205 BC.
Fish farming for your health and the planet's
Olive Heffernan takes us on a trip to the past with her views about the future of seafood production and her criticism of modern aquaculture (16 September, p 22). The issues she presents are the same as those that naysayers have used to try to prevent aquaculture development for decades.
Aquaculture continues to grow steadily and to go mainstream. It has surpassed beef production and contributes to over 55 per cent of total world seafood production. Aquaculture scientists and the industry have made enormous progress in improving the ecological efficiency of the process.
Fish farming for your health and the planet's
Heffernan asserts that developing crop-based fish feeds to replace fish protein and oil in aquaculture will add to pressure on land. This assumes that additional farmland will be required. Given that most fishes convert feed to flesh much more efficiently than cows, as well as producing healthier food and contributing less methane to the atmosphere, an alternative would be to reduce beef production and instead use available land to grow crops for fish feed.
For those not wishing to pursue a vegetarian diet, it makes more sense to eat farmed seafood than meat from terrestrial farm animals, both for their own health and that of the environment.
Electrobuses, pollution and the competition
Mick Hamer describes electric buses at the beginning of the last century on which depleted batteries were swapped for charged ones (9 September, p 35). Given people's propensity then to toss aside things they had finished with, petrol – even leaded – may have been a lesser evil than batteries for powering most vehicles. Imagine mountains of them, leaking heavy metal salts…
Electrobuses, pollution and the competition
The battery-electric bus was never going to succeed. By 1903, four years before the launch of the Electrobus, there were 300 electric trams running in London. Delivering power straight to the vehicle is more efficient than charging batteries, and removes the need to lug several tons of battery around. Battery-electric power worked for delivery vehicles well into the 1960s (and again now), but made no sense on a defined, unchanging route.
Trams have their problems, of course. In London, some were replaced by electric trolleybuses, which were quiet, economical and could pull in to kerbside bus stops. They carried more passengers than contemporary diesel buses.
The Tilling-Stevens company had been building hybrid petrol-electric buses since 1906. In 1924, it made a hybrid trolleybus that could carry on when the wires ran out – long before the Prius and other “new” hybrids. The mystery in all this is why London and other UK cities abandoned silent, non-polluting trolleybuses.
How to divide up data to maintain privacy
I entirely agree that it would be extremely dangerous to have one single super data repository (30 September, p 22). As you point out, the Estonian government is aware of this and deliberately keeps databases separate, albeit mutually communicating.
But it is far from obvious that the separation of data should be along national boundaries. It would be much better to devise some form of data-oriented separation. For example, health data could be kept separate from financial data and separate again from movement data. The correlation of such disparate data items is more likely to be of value to snoopers than to individuals, who regard these as separate areas of their lives. Classifying data by its nature rather than the geography of where it was acquired seems much safer.
Online democracy excludes many people
Niall Firth reports ideas for using blockchain technology, as used in bitcoin transactions, to “restore democracy” by enabling “liquid democracy” (9 September, p 8). The effect may be the opposite.
In every country there are many who do not own a computer, smartphone or any form of internet-accessing technology. It seems this new system is calibrated to ignore and exclude low-income citizens from the democratic process.
I doubt that any nation's off-net class would be confident in its interests being served by more affluent neighbours.
Fewer painful injections could save lives
You reported on “plastic cube injections” that can deliver a vaccine and its booster in one go (23 September, p 19). One reason that some parents fail to bring children for vaccination is the pain the child will experience through serial injections.
Reducing this number could increase uptake. The invention of injection has been in the 1650s. 快猫短视频 has often reported work on needleless vaccinations, for example on 24 September 1994 (p 19). Surely we can advance from the 1650s to the 2010s.
Nuclear power emits less carbon than other kinds
Ann Wills reports a finding that nuclear power generates a third as much CO2 per unit of electricity as conventional generation (Letters, 30 September). It's true that using fossil fuels to refine reactor fuel reduces the whole-cycle carbon efficiency of nuclear power, but that is all we can say. Solar, wind and even nuclear electricity are equally good for producing reactor fuel. Even if fossil fuel is used, a two-thirds fall in emissions sounds attractive.
There's no such thing as a free ride – or is there?
It would be nice to drive my Nissan Leaf car for free if an energy company will pay me to charge or drain its battery at certain times (7 October, p 7). But what happens if the grid has drained the battery just when I need to use the car?
The editor writes:
• The plan is to use little bits of lots of people's batteries, never draining any of them.
For the record
鈥� The source of the first gravitational waves detected is 108.5 times further away than the star Proxima Centauri (Last Word, 7 October).
鈥� Marcie Glicksman is chief science officer of Orig3n, purveyor of saliva tests (7 October, p 22).
鈥� We squished our spelling: the algebraic topologist who discussed how this branch of mathematics might be used to understand the brain is Ran Levi (30 September, p 28).
鈥� The figure given for potential energy production from evaporation in the US should have been 2.85 billion megawatt-hours (10 exajoules) a year (7 October, p 19).