Misanthropic principle
If Paul Davies says that the universe is bio-friendly, then I say he hasn’t taken a good look at it (30 June, p 30). The universe is bio-tolerant, maybe, or better yet bio-indifferent. Looking at the night sky, I do not see a cosmos optimised for producing life. It appears to be optimised for producing vacuum.
Even if the universe somehow “needs” life, it evidently doesn’t need very much of it. Perhaps, from the cosmic point of view, life is a necessary evil, to be tolerated and limited.
I call this the misanthropic principle 鈥� it certainly fits the facts better than the anthropic principle does.
From Bob Muirhead
Why all the fuss about the universe being finely tuned for life (30 June, p 30)? We might with equal logic say it is finely tuned for granite, or blue skies on Earth, or whatever bit of observable reality we like to choose. In a cosmic sense, life is just one component of the universe.
For the human inhabitants of one small planet, who can’t even explain the greater part of the universe, to place their form of life in a special position strikes me as a trifle arrogant.
Port Melbourne, Victoria, Australia
From Stu Smith
Paul Davies sidesteps one critical point in his discussion on the laws of nature and their relation to us as sentient observers 鈥� what makes our “observations” special? Unless he’s suggesting some sort of duality between matter and mind, I can’t see any reason why one particular arrangement of particles in one particular species’ brains should be special enough to alter the development of the universe, more than any other particular grouping of particles.
Exmouth, Devon, UK
From Paul Bays
A recent week’s UK lottery numbers were 7, 13, 23, 40, 41 and 48. The probability of this set of numbers being chosen from the 49 available is about 1 in 14 million, yet we do not feel that any explanation is required for this extraordinarily unlikely occurrence. In contrast, when we observe that the lottery of the universe came up with physical constants appropriate for the emergence of life there is a tendency to declare that the lottery has been fixed. We look to outlandish theories based on “bubble universes” or “quantum cosmology” to explain it.
Why do we see these two situations so differently? The answer lies in human psychology, not physics. We recognise that, to the lottery machine, one set of numbers is just the same as any other, yet we cannot help but see the distinction between a universe with life and one without it as hugely significant. There is no reason to think it is of any significance to the universe, and so no need to look beyond blind chance for an explanation of the “Goldilocks enigma”.
London, UK
Melanoma risks
Jessica Marshall mentions the known risk factors for developing malignant melanoma as sunburn during childhood and being red-haired or having a lot of moles (30 June, p 38).
There is another risk factor, which may become increasingly significant in the UK: not being immunised against TB with the BCG vaccine. In England, BCG was until two years ago offered to all 14-year-old schoolchildren, but it is now provided only in high-risk areas. This could mean that over the next 20 years we will see a rise in skin cancer rates in the UK to meet those of the US. It might be worth reintroducing BCG for this reason alone.
Jessica Marshall’s superb article reminded me of a chemical question I have long pondered. In Australia, cinnamate compounds are common components of suncreams and are approved by authorities such as the Cancer Council of Victoria.
I. L. Finar’s Organic Chemistry, from my student days, says that when cinnamic acid is irradiated by UV light it dimerises to form two cyclobutane derivatives: truxinic acid and truxillic acid. These appear likely to be very reactive. Would this be a source of further radical mischief on skin?
From William Grant, Sunlight, Nutrition and Health Research Center
Additional evidence on the role of UVA radiation in melanoma suggested in your feature can be found in trends of mortality rates for melanoma and non-melanoma skin cancer (NMSC) in the US. Between 1970 and 1994, NMSC mortality rates fell by about 40 per cent compared with the period 1950 to 1969: this drop can be attributed to sunscreens that blocked UVB well but UVA poorly. During the same period, melanoma rates increased by about 65 per cent.
I would, however, take issue with your feature’s suggestion that solar UVB doses in London (52掳 north) are high enough in summer for 10 minutes’ exposure per day to produce the 1500 International Units (IU) of vitamin D now thought to reduce the risk of cancer by 30 to 50 per cent: it takes 20 minutes in San Francisco (37掳 north) for a young, light-skinned individual with about 15 per cent of their body fully exposed to the sun. Older people are less efficient at producing vitamin D and so would need even longer in the sun. In England on a sunny summer’s day, it would take most people more like an hour to generate 1500 IU of vitamin D.
San Francisco, California, US
鈥� While some studies suggest higher levels of vitamin D may be beneficial, as William Grant points out, the official recommendation is for 200 IU per day before age 50. The sunshine exposure times in the feature were based on this figure.
Obesity and overheating
Ian Roberts makes a compelling case for the link between obesity in the US and global warming (30 June, p 21), but I think he touches too lightly on the issue of air conditioning. Overweight Americans are indeed likely to turn up the air conditioning at home, as their excessive weight and low metabolic rate contribute to a feeling of discomfort at what most people would consider to be reasonable temperatures.
Shopping malls, office buildings, public transport vehicles, movie theatres, churches and so on also crank up the air conditioning to cater to the needs of these heavyweight people 鈥� so much so that one might wonder whether people who frequent these public facilities might want to put on a few pounds just to keep warm.
Shops in warm-weather resorts often prop open their doors to create a draught of cold air that they hope will beckon people to step inside and cool down. I shudder to think of the amount of energy we waste in this way.
Reality rally
John Bell was not, as Michael Brooks asserts (23 June, p 30), a believer in local realism; he was a believer in the global non-locality called for by David Bohm’s alternate formulation of quantum mechanics, which also replaces quantum randomness with determinacy.
It’s not too hard to choose between a real, deterministic universe and one with no objective reality and inherent randomness. Every minute of work devoted to chasing down the notion of non-reality is a minute that could have been devoted to finding the correct deterministic and non-local theory. Once we have that, physics will stop spinning its wheels and will race towards the finish line of the grand unified theory.
Ancient ants
Beth Geiger’s gold-digging termites are nothing new (30 June, p 35). The Greek historian Herodotus wrote in the 5th century BC that in the deserts of India there was “a kind of ant of great size 鈥� bigger than a fox, though not so big as a dog” which threw up sand as it burrowed, just as regular ants did.
This sand was rich in gold, but getting it was said to be perilous. The operation had to begin at the hottest part of the day, when the ants were underground 鈥� and the heat was so intense that “the natives had to soak themselves in water to make it endurable”. The ants would smell the raiders and give chase: “nothing in the world can touch these animals for speed” and only a female camel, remembering her young, would make it home.
Herodotus has a reputation for being fanciful, but some of his outrageous stories have been wholly or partly supported by later archaeology or science.
Sense decimated
Feedback wonders about the 99.999 flights offered by a European airline (30 June). Might I suggest that the “.” is not a decimal separator, but rather a thousands delimiter? In the UK, twelve thousand four hundred pounds and twenty pence would be written as 拢12,400.20, but in mainland Europe that number of euros is written 鈧�12.400,20. Perhaps SkyEurope assumed the comma and full stop were used the same way around in the UK.
Trust trap
Feedback discusses people using oxytocin to influence those they meet (30 June). But the wearer would receive a much larger dose, their nose being in closer and longer contact with their own body than with anyone else’s.
Wasn’t this discovered in testing? Or did the product just make them so mellow and trusting that they didn’t care?
Life line
The article “Life 鈥� but not as we know it” by Douglas Fox (9 June, p 34) was interesting but did not address the definitions of life, the theoretical mechanisms discovered by work on artificial life, nor the reasons why evidence shows that life must be rarer than many people hope.
Biologists agree that live organisms metabolise, grow, respond to stimuli, reproduce and evolve. The Gaia hypothesis predicted that we would not find life on Mars because life has another property: it modifies its environment to make it more stable and hospitable to itself. Mars has shown no such stability; nor has Venus.
Even before the structure of DNA was discovered, the mathematician John von Neumann’s work on self-replicating machines suggested a model in which a description (the genotype), a translator to read it (the ribotype) and the resulting structure of the organism (the phenotype) are all necessary for life. Fox also fails to address Fermi’s paradox: if every planet promises some sort of exotic life form, then where are all the intelligent ones?
Reality rally
You cite experiments by Markus Aspelmeyer and Anton Zeilinger at the University of Vienna in Austria as implying that “we have to abandon the idea of an objective reality” (23 June, p 33). If we accept that what we call “reality” is simply what we experience 鈥� and that whatever we commonly experience, we can call “reality” 鈥� then maybe we need not overly concern ourselves about what happens at or below the quantum level.
If we decide to dig so deep, we discover that what we call “fundamental” particles are actually rather ghostly. We can’t fully measure them in the same way as we can experience making reproducible measurements on individual macroscopic objects. But they are in a sense more real, if the reality we experience is no more than an emergent property of statistical processes that operate on populations of these fundamental particles.
Maybe whatever fundamental reality underlies the processes that enable us to experience a physical world cannot be seen through the the reality we inhabit: that is, there is no mirror in the world that we can hold up to the world. Furthermore, as pointed out by Douglas Hofstadter (10 March, p 46), the identities that we experience as “you” or “me” are also nothing more than illusions.
What this boils down to is that an unknowable consciousness, through the medium of patterns of identity such as “me”, is indirectly experiencing an equally unknowable underlying physical reality, through the experience of our apparent reality. The remaining question is, what or who set all this up in the first place?
Don't blame cats
The quality of the research concluding that “cats could be scaring birds out of our cities” is revealed by Andy Beckerman’s reported comment (16 June, p 22): “What’s cool about the model is that with no mortality you still get a large decline through mechanisms of fear”. To reword that: what’s cool about the model is that, even without what we’re saying is the cause of the effect, we still get the effect by throwing in a self-fulfilling prophecy. Cool, yes. Good science, no.
Cats have been in cities for a very long time. If cat predation was a major, let alone the only, factor, then bird numbers would have stabilised decades, if not centuries, ago.
Rather than building virtual computer models, it would be better to look at the real world. In my city garden I have a holly tree where wood pigeons have nested safe from cats for many years. In the past two years they have not raised any young and I have seen magpies attacking their nests and found the shells of eggs they ate.
I suggest that the researchers look at history and at the present, then model the real predators.
For the record
鈥� An editing error meant we suggested that a fertility treatment called pre-implantation genetic diagnosis (PGD) reduced a woman’s chances of having a baby (7 July, p 4). We meant to refer to a technique called pre-implantation genetic screening (PGS). Both involve taking a single cell from an early embryo and screening it for abnormalities; PGD looks for specific mutations that cause a disease while PGS looks for abnormalities in the number of chromosomes. We apologise for the mistake.
鈥� Robin Blume-Kohout has moved from the Los Alamos National Laboratory in New Mexico to the California Institute of Technology in Pasadena. We also misspelled the first name of his colleague Wojciech Zurek (“Quantum states undergo natural selection”, 30 June, p 18).
Misanthropic principle
Paul Davies embraces John Wheeler’s idea that we help to create our history right back to the big bang by observing it, but fails to grasp the theistic nettle lurking within (30 June, p 30). The power of human observation is presumably insufficient to ignite the big bang (we hardly have the power to erase our own mistakes), but who can say what our descendants a few billion years hence will be capable of? Just as we today are becoming masters of determinism, able to create what we want when we want it, so perhaps the beings of the future will be masters of Wheeler’s “reverse causality”, able to invoke exactly the physical universe they need to satisfy their spiritual aspirations 鈥� a heaven on Earth, one might say. Davies needs to explain, then, why we should not call these future beings gods 鈥� especially as they will have created us.
Badger balance
I would suggest that it is both mistaken and unfair to say that farmers are “in denial about the real cause of bovine TB” (23 June, p 9). It certainly does not accord with the views of any of the farmers that I know. I do think, however, that both sides in the bovine TB issue have failed to consider and recognise the lessons of history. Human TB declined when the public health issues of overcrowded housing and poor nutrition were gradually addressed, before any TB antibiotics had been developed.
Since badgers became a protected species, their population has expanded in some areas to the limits of the food supply. Demand for cheap food has led to intensive agricultural practices with high stocking rates. Any infected animal, either badger or cow, is thus more likely to infect others, both badger and cow.
You say that the report by the Independent Scientific Group on cattle TB “rubbishes the dogma” that badgers spread TB to cattle, and that cattle TB increased in areas beyond the badger culling zone perimeter as infected badgers left the zone. These two assertions are incompatible, but we can conclude that culling was incomplete and that a significant number of badgers moved on to new areas. It is hardly a surprise that culling was an expensive failure.
I believe that the problem will not be solved until we can return to country-wide control and management of badger numbers, together with agricultural policies that allow farmers to earn a living without having to resort to over-intensive livestock management. Farmers are caught between the badger lobby on one side and our demands for cheap food on the other 鈥� they aren’t the ones in denial about the real cause of bovine TB.