Causal emergence has opened Pandora's box
Causal emergence 鈥� the idea that the cause of some events can’t be found at the microscopic level 鈥� is revolutionary in more ways than one (28 May, p 44). The concept seeks to explain physical phenomena that can’t be reduced to the current pillars of physics: relativity, quantum physics and thermodynamics. This idea must include new physical laws, independent of the established set, and would give a significant role to macroscopic information.
Communications engineering has a sophisticated information theory of its own, which includes the idea of information entropy, a measure of how deterministic a system is. Might incorporating this concept into classical thermodynamics prove sufficient to explain causal emergence? Might it offer up the missing physical principle, or will we need to create a new theory as a fourth, independent pillar of physics? Wherever this leads, information will take centre stage.
More enduring outfits bring many benefits
The best solution to the huge environmental problem posed by fast fashion is to encourage the manufacture and purchase of considerably fewer, but higher quality, garments 鈥� particularly those that could be classified as “eternally fashionable” (4 June, p 38).
Manufacturers would probably lose out a little, due to producing clothes more slowly and carefully, and using better quality materials. But these garments could then be sold at higher prices. Also, a “green production” label would be a hit with customers, especially in high-income countries.
More garments like jackets could be made reversible, thus offering two designs to increase appeal. Higher-quality clothes are almost certain to be worn for longer and, ultimately, to be more suited for resale at charity and second-hand outlets. Here in Australia, such stores have to discard many donations of poor- quality items due to deterioration.
Nuclear power? Better the devil we know
In a low-carbon future, the need for nuclear power is probably inevitable (28 May, p 38). For those who worry about radiation from nuclear waste, consider this: what would be better, to have this waste stored somewhere known and safe for thousands of years, or to suffer an indeterminate period, perhaps millions of years, of worldwide, incomprehensible damage to the climate 鈥� assuming we cannot control our emissions and climate change worsens?
How to explain the physics of flying upside down
I understand Chanda Prescod-Weinstein’s problem with the physics of flight (11 June, p 28). As a designer and builder of model aircraft when young, I found references to Bernoulli’s principle were quite unhelpful to explain lift, especially when considering a wing with an identical top and bottom.
The missing element in most of the Bernoulli expositions was something called angle of attack, which refers to the orientation of the wing in the pitch axis, relative to direction of travel. If the leading edge of the wing is higher than the trailing edge, it creates lift.
The mystery of inverted flight is resolved by knowing that pilots can pitch up the nose of their aircraft, which restores the angle of attack relative to the flight path while inverted. This mode of flight increases drag, so is merely inefficient, not mysterious.
Flying foxes may be democratic too
You report that “Jackdaws ‘vote’ on mass exodus” before taking flight together (28 May, p 23). At Cape Tribulation Tropical Research Station, my colleagues and I believe we have seen similar vocal behaviour in spectacled flying foxes (Pteropus conspicillatus). For several hours before a colony-wide relocation, there is a massive increase in squawks, screeches, chattering and general “conversation”. Could this behaviour be common across different flying species?
High time we dusted off The Limits to Growth
To add to the letter on degrowth, 50 years ago, a report called The Limits to Growth was published (Letters, 4 June). This was based on work at MIT, yet was ridiculed by economists, politicians and bankers. It was years ahead of its time. Every word of it is now coming true and it should be dusted off and made top of the agenda at the COP27 climate summit. If world leaders aren’t prepared to stand up and say that there are limits to growth, there is no point in having a COP28.
Nectar-guzzling urban bees remind me of something
Graham Lawton writes about the plight of the bumblebee versus the honeybees kept by urban hobbyists (21 May, p 28). The analogue to humans seems obvious: overly dense communities of urbanites muscling in and mindlessly using resources, while pastoral folk and the wider environment suffer most of the consequences.
Given recent history, even 2掳C seems beyond us
In 2020, the world almost totally shut down due to covid-19, but we only saw a emissions of around 6 per cent (Leader, 11 June). Given this, there seems no chance of getting the yearly cuts needed to limit temperature rise to 2掳C. Global warming is happening and happening big. Claiming anything else is holding out false hope.
Bikers can see clearly now the insects are gone
You recently reported on insect decline as measured by bug splats on cars (14 May, p 23). I have ridden motorcycles for 61 years. During that period, bug splats on screens and helmet visors have declined considerably. I always had to carry visor cleaning equipment, with which I regularly removed the remains of a serious number of bugs, but no longer.
For the record {25 June 2022}
Our look at the condition known as brain fog that can result from covid-19 featured Courtney Shukis (11 June, p 38).