Editor's pick: Oh, to be so certain that no computer can be conscious
Alun Anderson reviews The Feeling of Life Itself by Christof Koch and claims that computers can never be conscious (2 November 2019, p 28). I recall you reporting Danko Nikolic saying that machines “cannot exceed human intelligence, ever” (26 March 2016, p 23). Before this, many others said that a computer would never beat all humans at chess or Go, translate a language or recognise human faces.
Yes, a general-purpose digital computer is deterministic, agentless and without self-causality. Yet it can be programmed to simulate anything, including non-deterministic, self-causal systems unlike itself.
It may be that simulating a system capable of exhibiting consciousness isn’t computationally feasible for a Turing-type computer of any power. But the article’s description of “animats” as evolving non-biological creatures used to investigate consciousness suggests the possibility of constructing something that is somewhat self-causal. This may be difficult, but we know the laws of nature don’t preclude it because we experience consciousness ourselves and we are bound by those laws. The only way to rule out computers achieving consciousness is to fall back on a dualism between the mind and those laws 鈥� in which case, there is no point in discussion. Dualism, like any faith-based belief, isn’t amenable to scientific enquiry.
How to achieve low-carbon domestic energy supply
Readers Karen Hinchley and Jeremy Hawkes discuss ways to make homes net-zero carbon emitters (Letters, 30 November 2019). Renewable electricity, or maybe nuclear energy, can power heat pumps, either in individual consumers' homes or as district heating suppliers. Heat pumps are already widely implemented technologies and provide near-zero-carbon heating and cooling, which will be increasingly needed as climate change progresses.
They emit less carbon per unit of heat delivered than biomethane, which is in limited supply in any case, or hydrogen from natural gas or from electrolysing water. Wind power has increased from 2 to 18 per cent of UK generation in just 10 years. In 2018, total renewable electricity generation, with continued falling costs, reached about 110 terawatt-hours. This is enough to power some 20 million domestic heat pumps. In cold weather, consumer heat pumps would produce about twice the energy they used as electricity, and district heating systems would generate three or four times as much.
So, even if homes still lack substantial insulation, the peak electric load for heating would be 100 gigawatts or less, with a few hours of storage. All near-zero-carbon options require investments in these technologies, and also in networks and storage. There is no free carbon-free lunch.
Solar panels are useful, not least for hot water (1)
You quote energy efficiency consultant Russell Smith, who says home solar panels aren’t always the best way to cut carbon (9 November 2019, p 18). I presume he is talking about solar photovoltaics. I have these and a solar hot water system on my roof. The latter has been the best purchase I ever made. Storing the water is simple and doesn’t need expensive converter technology or limited-lifetime batteries.
As long as the system is kept clean, output doesn’t diminish over time. Every part is easily recyclable. For six months of the year, we get free hot water for a family of four, and for the rest of the year, it is at reduced price.
Solar panels are useful, not least for hot water (2)
I was pleased to read your article on energy efficient homes, but sorry that it is dismissive of solar photovoltaic panels. A properly designed system would allow all power generated to be used in the house or returned to the grid. Conventional power station generation and distribution is only 30 per cent efficient, so local solar generation saves around 2.7 kilowatts’ worth of carbon for every kilowatt used at home.
Here in Ireland, no newly built houses are allowed to install gas boilers. The only new systems allowed are heat exchange.
Trees are more important than a permanent solution
Adam Osen says an average person in a developed country releases about 14 tonnes of carbon dioxide a year, and a tree absorbs 22 kilograms a year on average (Letters, 7 December 2019). That is true, but it doesn't follow that everyone needs to plant 680 trees a year, because trees aren't a permanent solution.
They are much more important than that: they are a stopgap. The point of planting trees is to absorb a lot of CO2 over the next 100 years or so while they are growing and while we completely decarbonise every aspect of human activity.
This is the basis of the . With a human population of nearly 8 billion, we need to plant only about 130 trees each. This is completely feasible.
Recently, Ethiopia – a country with a population of 100 million and fewer available resources than many more developed nations – planted more than 350 million trees in just 12 hours.
Why weren't these effects of measles seen sooner? (1)
Debora MacKenzie reports that measles infection damages children’s immunity to other diseases (9 November 2019, p 15). When I had measles in the 1940s, it seemed very common for children to contract it again shortly afterwards.
It is interesting that present research suggests this may have really been an unrelated disease with similar symptoms.
Why weren't these effects of measles seen sooner? (2)
In the 1950s and early 60s, before immunisation against measles, there were typically epidemics of measles every two years, affecting up to half a million people, mainly children. The majority would have been immunised against polio, diphtheria, whooping cough and tetanus.
But I am not aware of any increase in the incidence of these infections in the years following measles epidemics.
I had measles in the 1961 epidemic. I recall tales about being able to have certain childhood diseases more than once, but this was attributed to the difficulty in distinguishing between different common diseases.
Could this actually have been a consequence of infection pre and post-measles? I find it surprising that the reported effect of measles on the immune system went unremarked for so long.
Let's deliver contraceptives to control feral cats
I understand Australia's need to cull its large feral cat population, which has caused tremendous environmental damage (23 November 2019, p 12).
But little has been done to provide chemical neutering for unfortunate stray and feral cats. Could the Felixer trap spray a contraceptive gel on feral cats instead of a poison?
Quantum computing, due at a superposition of dates
Quantum computers with practical uses could be decades away, says Chelsea Whyte (2 November 2019, p 9). Is it too early to predict that the first truly useful quantum computer will be powered by the first truly useful cold fusion generator?
For the record 鈥� 4 January 2020
鈥� Our histogram shows the sources of microplastics that enter the sea in that form, not including the 70 to 85 per cent that enter as litter (7 December 2019, p 38).
鈥� The motor in an electric car is an example of a moving magnet giving rise to an electric field only when it becomes a generator for the purposes of regenerative braking (30 November 2019, p 42).