Editor's pick: To spot cleanliness, you must look properly
Where did David H. Freedman get the idea that people without servants didn't worry about tidiness before the 1950s (19 January, p 22)? This seems to be a case of a judgement made by looking in the wrong direction. Tidiness is mentioned in cookbooks from the 17th century. It is there in condemnation of slatterns pretty much all the time. From the mid-19th century, it becomes an absolute cornerstone of domestic science. The even became obsessed with the “tidiness” of the contents of a plate.
It is a key theme in the books for girls by Louisa May Alcott and , such as Anne of Green Gables. It is obsessed about in girls' school stories in the first half of the 20th century, in which learning to tidy up after herself is often the first initiation of a girl into school culture.
There is a theme here: the labour of tidying up is, and always has been, assigned to women. Men have the privilege of not noticing it, either now or, apparently, in the historical and literary record.
My own personal exercise paradox
After my regular 30-minute stumble around the local cemetery, I read with interest that I can't just burn off extra calories (19 January, p 30). Admittedly, I exercise for the endorphin kick and because it makes me laugh. But when I was gardening for 4 to 12 hours a day, I could eat and drink whatever I wanted without much weight variation. I was slim and strong, although generally gained 3 kilograms over the winter months.
Now I dance, do yoga, run and walk almost everywhere – I haven't had a car for more than 20 years, nor a TV. I am neither strong nor slim. I gained weight in the year recuperating after an operation and have been unable to shift it. The consensus seems to be that it is my age – I'm now over 60 – although I recall disputes over this. Is this the case?
First class post 鈥� 9 February 2019
Could those who don't have this DNA be given it through some type of gene editing?
Laurel Kornfeld in the finding of pieces of DNA associated with lower body weight (2 February, p 20)
Most workers have little flexibility in their day
Graham Lawton discusses how to organise your day (12 January, p 34). I nonetheless found myself wondering to what proportion of the working population his remarks had any relevance.
I thought of production line workers required to sustain a constant input from clocking in to clocking off. I thought of teachers, who need to be up to speed 1 second after the 9-o'clock bell; of train and bus drivers and airline pilots; and I thought of my own working life in which my staff and I needed a whole hour of intense preparation before our first patients began to arrive at 8.30 am or earlier.
Recognising that Lawton's presentation may have had its tongue slightly in its cheek, I still wonder: who are these drones who can afford to swan around for an hour or so before attempting to achieve anything and then perhaps take a power nap when they feel like it, or manage to find natural light, or afford to fit in a lunch break at all?
We need a replacement for a standard light
Leah Crane tells us that batteries on the New Horizons spacecraft can power the equivalent of three standard light bulbs (5 January, p 7). What is a “standard light bulb”? Once upon a time, I might have imagined a 60-watt filament bulb, but they are obsolete. It would make more sense to say how many watts they can supply.
The editor writes:
• The batteries deliver 190 watts, and we were indeed thinking of 60-watt bulbs.
How do you rebuild or overthrow cashlessly?
Breathless anticipation of a cashless society seems repeatedly justified on the basis both of convenience and its potential to undermine informal and criminal economies (12 January, p 22). But serious issues are overlooked.
After natural disasters that take out electronic communications, such as solar storms and hurricanes, cash has a vital role to play in maintaining purchasing abilities until normalcy returns.
As Donna Lu acknowledges, illiterate, underprivileged and electronically isolated people will suffer if cash is eliminated. And from time to time, societies have legitimately overthrown authoritarian governments and tyrants. How will this be possible if all transactions can be tracked or people can be blocked from obtaining the things needed to do this? Or will we, like criminals, have to create our own coinage from precious metals, gems and high-value small objects as we have done in aeons past?
It is difficult to date Australia's figurative art
Stuart Leslie suggests that the oldest figurative art in the world produced by Homo sapiens may occur in Australia (Letters, 5 January). He says that some depicts the giant flightless bird Genyornis newtoni and that this appears to have become extinct around 46,000 years ago.
But the rock images that were proposed, on the basis of their large size, to be depictions of this bird occur alongside the more distinctive ones of dingos, which were introduced into Australia less than 4000 years ago. And Bruno David of Monash University, Australia, that the surface of the rock mass upon which the disputed image appears wasn't exposed until after the bird's extinction.
It is true that the study of rock art has a Eurocentric bias despite more of it occurring in Australia than any other place in the world. But, in general, it is notoriously difficult to securely date rock art and very few of the proposed datings stand up under close scrutiny. Australia may have the oldest “art”, but this hasn't been demonstrated to date.
How are you reading readers' minds?
In late 2017, I decided to give a talk on fire to a science discussion group in the University of the Third Age. The occurrence of a supernova when savannah appeared (14 October 2017, p 7), black kites taking burning twigs to start new fires (13 January 2018, p 4) and Neanderthals hardening wooden spears in the fire (10 February 2018, p 15) all featured in your pages in the following weeks.
A year ago, I offered a talk on water and was hit by a deluge of articles on water, including the news that it can be considered as two liquids (2 June 2018, p 26).
I decided to write to thank you for this support and to let you know that the following talk would be on Earth, completing a discussion of three classical elements. Before I got around to it, you published an account of the first 3.5 billion years of life here (12 January, p 28).
Have you teamed up with a tech firm to read your readers' minds?
First video recordings of lunar meteor impacts
I have been collecting lunar meteor impact recordings since November 1999, during the Leonids meteor storm. I believe I was the first to do so. I now work with the , a volunteer research organisation.
You say that the observation of a lunar impact on 21 January was the first during a lunar eclipse (26 January, p 6). George Varros, a fellow amateur astronomer in Maryland, probably recorded two impact flashes during the total lunar eclipse of 20 February 2008, although he logs these as unconfirmed and, unlike this year's, they weren't recorded by anyone else.
A space elevator seen as a weight on a string (1)
Kelly Oakes suggests that a space elevator needs to be tethered at the equator to avoid hurricanes. (12 January, p 42). Regardless of weather, it must be terminated at the equator since its centre of mass must be in geosynchronous orbit. All such orbits are directly over the equator as defined by the spin axis of Earth.
As Oakes says, there would have to be some flexibility in the structure so it can be moved out of the way of hazards. Since there would ideally be no net force holding it to the surface – it is effectively hanging from space – this wouldn't be a problem. But the termination point couldn't be pulled very far from the equator without feeling catastrophic lateral forces.
A space elevator seen as a weight on a string (2)
Have the proponents of the space elevator done a risk assessment for a manufacturing error that results in a cable of length similar to the c ircumference of Earth coming whirling down?
So how big is this Jupiter-sized black hole then?
You report that there may be an intermediate-mass black hole the size of Jupiter in our galaxy (19 January, p 14). Wouldn't one of these have significantly greater mass than the planet?
The editor writes:
• The diameter of the event horizon of the suggested black hole would be roughly Jupiter's diameter. The it would be about 30,000 times the mass of our sun.
Skullcaps offer closer contact with brainwaves
Jim Skeels suggests that neural activity could perhaps be recorded closer to the source through a dental implant, which may also be less obtrusive than a full EEG cap on the skull (Letters, 1 December 2018). This is an interesting idea, but a midline slice of the skull shows that a tooth implant would be further away from the brain than a skullcap and signals would have to go through more bone.
For the record 鈥� 9 February 2019
• We printed photographs of the Extreme Light Infrastructure laser installation near Prague in the Czech Republic (26 January, p 40).