Half a century is too long to wait for net zero
Adam Vaughan sees hope in the fact that India’s prime minister has pledged that the country will achieve net-zero emissions by 2070 (6 November, p 10). However, promises made by ordinary people, let alone politicians, for 50 years in the future are clearly meaningless.
Imagine if Lenin had promised a global utopia by 1967, following the October Revolution in 1917, or if the Allies at the end of the second world war had promised enduring world peace by 1995. What we need to hear is what they will do today.
One easy way we can turn down Earth's thermostat
Ingrid Newkirk, People for the Ethical Treatment of Animals, Washington DC, US
Hurrah that many nations have pledged to stop razing forests by 2030, but, at the rate they are being felled, will any be left by then?
Reactions to the COP26 climate summit show that while many are unhappy with the failure to take the kind of drastic actions needed to save us from tempests, droughts, fires, floods and species extinction, most people behave like dependent children, leaving it to others to protect them (6 November, p 9). We need to take personal responsibility.
Most forests are destroyed to grow crops to feed cows and chickens. The way to silence the chainsaws is to end demand for meat and dairy. We can all do this.
Time to wheel out the CO<SUB>2</SUB>sucking machines
COP26 focused on persuading all nations to aim for net-zero carbon emissions by 2050, in the hope this will prevent global temperature rising by any more than 1.5掳C (23 October, p 36).
The major polluters are unlikely to meet the first target, and so the second will probably be exceeded in the near future. Hence, we need massive investment in the technology to capture carbon dioxide from the atmosphere. This gas can be liquefied and buried.
The resources of the fossil fuel industries should be switched to this purpose as a matter of urgency and the UN should set up a Centre for World Temperature Control. The global temperature has already reached 1.2掳C above pre-industrial levels and clearly even this is far too high.
Maths makes your daily commute less jarring
Cedric Lynch, Potters Bar, Hertfordshire, UK
In your story about the upgrade to the branch of maths called calculus, you say “you could perhaps imagine calculating the rate of change of acceleration too, which would be a third-order derivative” (13 November, p 44).
However, calculating this rate of change can be of more than just obscure academic interest. In the early 1970s, it saw practical use in the development of a new train, which from 1976 to 2019 was the mainstay of the service to my home town. Because it was designed for routes with frequent stops, this train was capable of very rapid acceleration.
Experiments were done to find out how large abrupt changes of the rate of acceleration could be before passengers would object to them. This information was used to determine how to set up the train’s motor controller, in order to limit acceleration changes.
Perhaps 'burial' was really just a game gone wrong
The skull of a small child found on a ledge in a cave with no signs of carnivore activity or large-scale water movement doesn’t indicate to me that it is firm evidence of the early human species Homo naledi burying its dead (13 November, p 9). Young children hide in nearly inaccessible places as part of their games. Child’s play could be a plausible explanation.
Votes for reality despite the quantum puzzle
Regarding Albert Einstein’s wish, amid conundrums on the nature of reality thrown up by quantum theory, that he could be sure the moon was still there if he wasn’t looking at it (6 November, p 38). I wonder if a related question sheds any light on this: is the sun there if I am not seeing it at night? As the moon is visible thanks to reflected sunshine, the answer is: yes, the sun is there, as you know by seeing the moon.
My guess is that reality is real at our macroscopic level, because the uncertainties at the microscopic level disappear when you zoom out. The result of a single coin flip is uncertain, but there is certainty that a million flips give a roughly 50-50 split of heads/tails. Large numbers take the uncertainty out of reality; in fact, large numbers make reality. That is why we get such strange results if we look at tiny objects or just a few of them.
Votes for reality despite the quantum puzzle
Quantum mechanics doesn’t predict that the moon isn’t there when you aren’t looking at it, but that you can’t simultaneously measure its position and momentum (and other properties) with absolute certainty. However, the uncertainty is defined by Planck’s constant, which is so small that the effect is insignificant for visible objects.
Recycling metals can ease the renewable transition
The increased demand for minerals to build renewable energy kit, such as wind turbines, solar panels and mega batteries, emphasises the need for a circular economy in which the necessary minerals, once extracted from the ground, are never reburied as waste, but reused again and again (13 November, p 38).
It also highlights the necessity of using, when possible, minerals that are common and easily found. For instance, , batteries that use only zinc and bromine and other versions based on iron and vanadium. Any innovation that reduces the use of less common metals should be promoted.
Two brain health boosts for the price of one
I have an idea regarding lifestyle approaches to try to reduce the chance of developing Alzheimer’s disease (6 November, p 46). Older people aren’t in a position to wait for a drug cure, so every beneficial lifestyle strategy should be practised.
Two important ideas have been suggested: getting seven hours of sleep and taking on a cognitively challenging activity. These can be combined if you study a difficult language such as Latin just before bedtime. In my experience, sleep follows quickly.