Life in the shadows
Colin Barras’s article on the newly discovered eukaryota among the deep earth biota was fascinating (27 April, p 36). Presumably, they are dependant on local bacteria for nutrients.
Since the 1930s we have known about microbial life capable of independence from sunlight: the sulphate-reducing bacteria that accelerate anaerobic corrosion of iron and steel. They consume the hydrogen that protects metallic iron from rusting.
Wet iron is hardly a viable primary energy source to support an ecology evolving over millennia. But in that hot South African gold mine, the local sulphate-reducing bacteria are different because their hydrogen is formed by the radiolysis of water when thorium or uranium decays. Thus they would seem to be primary producers for an ecology based on a non-solar energy source, yet one that has the continuity necessary to underpin evolution.
If so, these findings, as you say, have valuable consequences for our speculations on the existence of extraterrestrial life.
Are we alone?
You report the discovery of two exoplanets orbiting in the Goldilocks zone of Kepler 62, and speculate on the evolution of life there, even the possibility of it having evolved on each planet (27 April, p 10).
Although I believe that we should continue to look for extra-terrestrial life, I do not expect that we shall find it. While life is abundant on Earth, current theory has it that it is descended from a single ancestor cell. Yet Earth abounds with suitable habitats, so the conclusion must be that the initial emergence of life is highly improbable, and has happened just once in over 3 billion years on a highly suitable planet.
Going underground
While Paul Younger is correct that ground source heat pumps do not work well with radiators designed for water at 70 掳C (4 May, p 34), he has overlooked two things.
Much UK housing had its heating designed before adequate insulation became the norm. Once insulation is improved, radiators can work with water around 40 掳C. Heat-pump systems also operate continuously, unlike traditional on/off radiator systems. Having installed a heat pump in a 1970s property, I can vouch for all this.
Rock of ages
You described Rita Cabral’s surprising discovery of sulphur isotopes that formed under intense light (27 April, p 14), yet were found in volcanic ocean basalts only 20 million years old.
She concludes they were derived from oceanic crust that was at the surface 2.45 billion years ago when Earth lacked an ozone sunscreen and sank via subduction before rising again. But it is difficult to see how such ancient subducted crust could have regained buoyancy and risen from the mantle, so there could be an alternative explanation,
Is it possible the isotopes could be from a large basalt achondrite? This type of meteorite comes from the crust of a planetesimal, or mini-planet, heated sufficiently by impacts, radioactive decay and gravitational compression to split into layers similar to those within Earth. Basalts on a planetesimal surface, lacking an atmosphere, would clearly have been exposed to intense light.
Second that
I approve of the notion that time is real (20 April, p 30). I suspect the mathematical physicists who think time is an illusion have forgotten that, just as the map is not the territory, the mathematics is not the physics.
Lee Smolin’s article on the reality of time was, is and will be very interesting.
Bluff Point, Western Australia
Corporate culprits
Fred Pearce’s review of two books about business and responsibility (27 April, p 50) has parallels with the way corporations have not been held to account amid the current global financial situation. What qualifications did and do the people at the top have?
And regarding the disastrous gas leak at a chemical plant in Bhopal, India, how near the top, in terms of authority to make final decisions, were chemists?
Not very clever
Your article on stupidity (30 March, p 30) reminded me of psychologist Arthur Janov’s observation that intellect and intelligence are not the same thing. “It takes a fine intellect to design and build a nuclear bomb,” he said, “but it is not a very intelligent thing to do.”
Banana appeal
Your interesting article on the origins of bananas mentioned mineral formations known as siliceous phytoliths in plant tissue, and said their purpose was a mystery (20 April, p 38).
However, they are known to provide beneficial effects, including enhanced resistance to fungal and insect attack, and, in crops such as rice, higher photosynthetic rates associated with a more upright growth habit produce bigger yields.
Magical mystery tour
Feedback has expressed concern regarding signs of restricted access to the third floor of the Department of Electrical and Electronic Engineering building at Imperial College London (16 March and 4 May).
But surely, all non-muggle folk are aware that the third-floor corridor is out of bounds to all who do not wish to die a most painful death?