Treating anorexia with the keto diet is very risky
I was very concerned reading your piece on the use of the keto diet as a treatment for anorexia. This diet has the potential to cause serious harm to someone with, or at risk of, an eating disorder (13 June, p 28).
The study your story references is a feasibility trial, which isn’t an evaluation of the effectiveness of a treatment. The trial was completed by only 18 participants, none of whom was even moderately underweight. This sample size is surely too small for any definitive verdict, and the study offers no insight into treating people with moderate or severe anorexia.
I am a mathematician and a science communicator, and I also understand anorexia nervosa all too well. In 2020, I spent two months in an inpatient psychiatric ward, fighting severe anorexia. I have also, sadly, lost three people to the illness. When I was ill, I ended up in hospital in ketosis. A friend also relapsed into anorexia after going on the keto diet.
I hope those at risk read this letter and know that the keto diet isn’t the answer.
One group that superager studies might have missed
As an introvert, I don’t have a wide social network. After reading various studies on superagers that recommended socialising, I wondered if I need to spend more time doing so to keep sharp (20 June, p 38).
However, after more research, I found that a lot of intelligent people kept working into their 80s, like Thomas Edison, the composer John Williams and a number of Nobel laureates. They may not be the kind of people you would encounter in farmers’ markets and retirement communities, and they may be too busy to enroll in superager studies, so this research may not apply to them. This puts me at ease with my preferred activities of learning and solving puzzles, not socialising.
The human element of the rise of killer robots (1)
You discuss the threat of fully autonomous weapons, programmed to kill without human intervention. In a previous era that saw the rise of a new and horrific way of killing 鈥� the spread of nuclear weapons in the decades from the end of the second world war 鈥� there was an interesting political development. A new breed of “nuclear pacifists” emerged, people who, though not previously against all warfare unconditionally, decided that the increased danger of nuclear weapons was such that the only answer was to renounce all war entirely (Leader and p 4, 20 June).
The pacifist movement at the time was greatly strengthened by the new influx. Perhaps this latest development will also horrify people sufficiently for them to completely abandon support for the existence of any military forces. As a pacifist, I hope this obscene new cloud does indeed have such a silver lining.
The human element of the rise of killer robots (2)
Your leader’s question of “whether [in warfare] a human should always be involved, ultimately responsible for the decision to pull the trigger, or whether machines can be allowed to act alone” assumes that there is a distinction. Yet in both cases, someone has made the decision to build and deploy the killer robots. Even when machines are set to act alone, a person has made the decision that a machine can pull the trigger.
More ideas on how to get to the TRAPPIST-1 system (1)
Writing in response to my letter about travelling to the TRAPPIST-1 system (6 June), Bryn Glover is, of course, completely right when he says that it would be practically impossible to get there while taking all your propellant with you in a 1 g spaceship (Letters, 27 June).
So, how about scooping it up as you go along? And accelerating it out of the back of the starship? Perhaps that could be done with the so-called dark matter that we are told fills our galaxy.
Does anyone know how to do this using weakly interacting massive particles (or whatever dark matter might be)? If someone can solve this, they will give us the key to the stars!
More ideas on how to get to the TRAPPIST-1 system (2)
Glover says “I can’t imagine how to calculate the mass of fuel that would be required” for a trip to TRAPPIST-1 and back. Surely all you need is the Tsiolkovsky rocket equation, which expresses the relationship between a rocket’s mass and the propellant required to move it, plus some assumptions about the astronauts’ needs for food, water and air.
People often say that something “isn’t rocket science”, as if rocket science is very difficult 鈥� but rocket science is really just that equation. It is rocket engineering that is difficult.
The joy of living alongside Earth's last dinosaurs
Regarding the subjects of your book of the week, Steve Brusatte’s The Story of Birds, I’m so happy to live alongside them in the bush on the outskirts of Wellington, especially the blackbirds. I often imagine them as dinosaurs, scuttling around very close by and doing raids to get food (13 June, p 22).
I have observed them for nearly 10 years now, and I know most of them very well. Blackbirds are great communicators, and they are excellent flyers when they want to travel through thick scrub and bush. They also seem to be highly individualistic.
Spotting Saturn's moons in a childhood hobby
The distribution of the 100-odd moons in the newly discovered Mundilfari group around Saturn reminds me of the distribution of individual shots on the paper target sheets I used to check my progress when learning to handle a shotgun as a boy on the family farm. I recall that the target sheet was about 30 metres from the gun. The spread of shots tended to be up to about 300 millimetres across, and the diameter of the gun barrel was about 10 mm (13 June, p 34).
Scaling that up to cosmic dimensions, it would seem to suggest the possibility that the Mundilfari group is debris from a distant stellar explosion, gravitationally captured by Saturn as it passed through the solar system.
For the record
In Close Encounters of the Third Kind, Roy Neary lives with his wife and three children (20 June, p 26).