Roots relaxation
That you can “Chill out to the rhythm of your heart” may be a recent discovery in Japan (27 July, p 13), but it is old news to fans of reggae music, which Bob Marley described perfectly decades ago as “the heartbeat of a happy man at rest”. Jah lives! Stir it up!
Letter
It’s the level of the floor that’s the problem. Most bathrooms in Australia at least have a drain and bathroom floors are not level, being laid to slope towards the drain. Conversely, most other floors in a house are designed to be level.
Having worked in laboratories for more years than I care to remember, I could not help but notice that nearly all laboratory balances come with a level indicator. Making sure that the balance is properly levelled is usually one of the before-use checks. And, surprise surprise, the displayed weight actually changes as the balance is levelled. I think it has something to do with vectors.
Can we move on from this insane topic now?
Don't look now
Your report says that scales placed on carpets show a greater weight (29 June, p 23), while Kenneth Hooton says his scales show a lower weight on a carpet (27 July, p 27).
We’ve noticed differences between different parts of our carpeted bedroom, but the most significant difference is controlled by whether we look at the dial. If we look down, we weigh about 0.3 kilograms more. Fortunately, our scales lock the reading once it stabilises, so weighing ourselves is not a two-person job.
Letter
In Mayhew’s London, a survey of London undertaken in Victorian times by Henry Mayhew, one of the occupations among the London poor that he described was that of “pure collector”.
Curing leather in tanneries included a process known as “puring”, in which the hides were soaked in a foul-smelling liquid whose main constituent was dog excreta. This excreta was known as “pure”, hence the job title of those unfortunates who collected it off the streets for the tanneries.
“Pure” is therefore “dog crap”.
Pure as mud
Feedback asks in what sense is the cranberry juice drink “pure” (27 July). An overpaid corporate lawyer would no doubt point to that word “drink” as the get-out. With all that added stuff, it sure isn’t pure cranberry juice, but who’s to say it’s not a pure cranberry juice drink?
Given the chlorine disinfectant, aluminium brightener and other stuff added to our water supply, it can surely be only a matter of time before corporate lawyers warn the water boards to refer to the liquid they send us as “Pure liquid water drink”.
Base bull
I have two quibbles with Erica Klarreich’s baseball article (20 July, p 19). First, her baseball terminology is wrong. It’s “home plate” not “home base”, and the modifier for “clean-up hitter” is never used as a verb to describe what the fourth man in the line-up should do.
Second, the article fails to address how a particular batting order will affect a particular batter’s performance. For example, if you put a light hitter behind a power hitter, opposing teams will, if circumstances allow, pitch around the power hitter to get to the light hitter, resulting in a lower batting average for the former. This is why Barry Bonds broke the home run record and the walks record in the same season.
On the cards
Every time someone writes about the number of permutations of 52 playing cards they seem to set down a different answer. Erica Klarreich says it is roughly 1058 in your feature (20 July, p 42). Surely it is closer to 1068 or 8 脳 1067 鈥� 52 factorial?
Perhaps the true number is actually a “recipriversexclusion” 鈥� a number whose existence can only be defined as being anything other than itself, a concept proposed by Douglas Adams in Life, the Universe and Everything.
This is correct. It means that the comparison with atoms in the Sun is less apt than it might be. It is more like the atoms in the Galaxy 鈥� Ed.
Living in sim
I was intrigued by Nick Bostrom’s notion that we might be living in a giant virtual-reality simulator maintained by far-future humans (27 July, p 48).
This is a staple notion of science fiction, as in my own Manifold series. And in an article published in the Journal of the British Interplanetary Society in 2001 I explored the Matrix idea as a resolution to Fermi’s Paradox (if aliens exist we should see them).
But the energy required to maintain a high-quality simulated world is large, and grows larger as our domain of understanding increases. I estimated that if we could establish a colonisation bubble 100 light years wide, the energy requirements to keep up the simulation would be larger than the mass-energy of the Universe. Beyond that point, presumably, we will know the truth.
Craters with rings
Yes, BP’s money can buy wonderful imaging, but it cannot necessarily buy a unique impact crater (3 August, p 19). There are several impact structures on Earth that are just as well-preserved and probably also retain concentric fracturing, but have not been imaged to the same extent.
The article claims that “no other crater on Earth has anything like [the 10 concentric fractures]”. This is not true. Phil Hawke of the University of Western Australia processed geophysical images of the 11-kilometre Yallalie feature in Western Australia. They show concentric fractures extending to a diameter of about 40 kilometres.
Researcher Phil Allen writes: Francis Macdonald is quite correct when he suggests that there are other “multi-ringed” impacts on earth. However, the nature of the fracturing at Silverpit is quite different from craters such as Yallalie. That one has large ring-faults, most of which appear to be part of the normal cratering process such as uplift and slumping. These have a comparatively large spacing with respect to the crater’s diameter. The ring-to-crater width ratio is quite different at Silverpit.
Writer Ralph Lorenz adds: Macdonald makes an important point. To date we have literally only scratched the surface of the terrestrial impact crater population. There may be hundreds more craters beneath the surface that can be discovered seismically, and perhaps a few may have external rings like those at Silverpit.
DNA's demise?
Your article on a future reduction in the world’s populations raises a question (20 July, p 38). Does it strike anyone else as odd that, despite the whole point of self-replicating DNA apparently being to make its pattern as populous as possible as quickly as possible, its evolutionary masterstroke of developing sentient intelligence is causing a reluctance to procreate, thus limiting its growth?
Australia is full
Perhaps Philip Smith of Texas would like to research some climatic information before maligning Tim Flannery (3 August, p 27).
Much of Australia falls into the same climatic zone as the Western Sahara, with rainfall of less than 200 millimetres a year. Kalgoorlie, where I live, relies on water piped 600 kilometres from Perth. The mean annual evaporation rate is 10 times higher than the mean rainfall. Kalgoorlie is not especially dry compared with other parts of Australia, but without that water pipeline, there would be no town here.
Smith states that “Australia can support many more people than present, based on other countries’ statistics.” Flannery has based his statements on Australia’s statistics and climate. No other figures are valid. Between 7 and 8 million people is sustainable 鈥� more is not.
Every cloud鈥�
Unlikely as it seems, I suppose that Ross Hoffman’s suggestions for manipulating the weather might be remotely feasible (27 July, p 28).
However, human behaviour is even more unpredictable than weather. One person’s drought might be the climatic silver lining of another’s tourism empire. Satisfy one and the other will sue.
The need for insurance suggests that we will never be able to control the weather.
Are we transmitting?
I read your article on SETI with interest (20 July, p 22).
Presumably, given that SETI is expending such effort on searching for signals deliberately broadcast into space by ETs, we are broadcasting our own such signal to help any counterparts with their own searches? Or are we merely relying on them picking up BBC Radio 4?
There have been a couple of token efforts to send out signals, but no mainstream SETI researchers are broadcasting. There are several reasons for this. First, no one knows where to direct signals, and to send them out in every direction would require huge amounts of energy. Then, there’s the socio-ethical questions: who should take itupon themselves to speak on behalf of all humanity, and what should they say?
That leaves BBC Radio 4, Big Brother and other radio-wave leakage as our only means of alerting ET to our presence. But don’t forget, we’ve only been broadcasting for the past 100 years, so the first of those signals won’t have got any farther than the nearest thousand or so stars in our galaxy 鈥� Ed.
Tunnel flaw
Your interesting article on methods to fight fires in the Channel Tunnel reveals a fundamental flaw in the thinking behind the tunnel’s design (3 August, p 11).
The stabilising jacks, which were the major cause of the inferno (though not of the fire itself) should not be mounted on the train but on the trackside at the loading/unloading bays.
This would mean the train would be relieved of several tonnes of useless deadweight and so run more efficiently. The hazard to train operation represented by each and every jack would be left behind when a train departs, the jacks would be withdrawn downward (instead of upward) and so would fall away safely. Maintaining and inspecting jacks would be greatly simplified and, with a little imaginative design, jacks could be replaced by a solid non-moving dockside construction from which the lorries embark.
Itinerant IUDs
A few weeks ago, while performing a laparoscopic operation, I retrieved an IUD that had become embedded just below the stomach of a 22-year-old woman. It had taken five months to migrate there from the uterus. Being a levonorgestrel-containing IUD, it had continued to provide contraception, albeit from an unusual location.
A couple of years ago I delivered a healthy 4-kilogram baby boy. The copper IUD that had been meant to prevent him was found stuck in amniotic membranes at the edge of the placenta. The parents, who thought this wildly funny, reclaimed the IUD and taped it into the infant’s photo album.
Am I really “pushing myths” when I mention this to my medical students, as you imply in your news story (3 August, p 9)? IUDs are fairly good contraceptives, but where there are IUDs, there are medical anecdotes about IUDs. When putting a foreign body into the uterus, which has three orifices and is subject to hormonal and mechanical stimulation, it should not be too surprising that a few IUDs do more than just lie there and perform their contraceptive duties while others don’t perform at all.
In the highly politicised and confrontational world of US sexual politics, one side preaches chastity and tries to brand all contraceptives with scary tales, while the other side declares that rational clinical scepticism is a denial of evidence and amounts to treason in the just war against unintended pregnancies.
The drugs industry must take some of the blame for the proliferation of IUD anecdotes. At least here in Europe, they staunchly refuse to make public the number of IUDs sold annually, thus making any calculation of how many women actually have IUDs at any given time (and how many of them develop complications) little more than guesswork based on small samples in family planning clinics.