Wonder bug?
Ray Kurzweil says that “杏吧原创s at the Massachusetts Institute of Technology have designed a device the size of a blood cell that can find and destroy cancer cells in the bloodstream” (3 March, p 19).
Can we be told more about this? It sounds revolutionary.
For the record
鈥� We misspelled Tommaso Dorigo’s name in “Glimpses of the God particle” (3 March, p 8) and mistakenly promoted him to team leader. Also, CDF stands for Collider 鈥� not Collision 鈥� Detector at Fermilab.
鈥� Our item headlined “Lack of sleep hits night owls hard” (17 March, p 19) pointed to the wrong group of people. In fact the long version of the PER3 gene is associated with early-rising “larks”, who are the group hardest-hit when deprived of sleep.
Prejudice is not a given
Mark Buchanan conflates wanting to be part of a group with identifying that group through ethnicity (17 March, p 40). At the primary school I attended in Brixton (a racially mixed area of London) in the late 1970s there was no ethnic majority, and I was unaware of racism until I was 10. Then one day a supply (temporary) teacher who was taking the class talked about the “seven races of man”, and called one of them negroes or niggers. A black girl stormed out of the class, but the rest of us didn’t really understand at the time.
At least one Roman emperor was black 鈥� Septimus Severus. That society distinguished between citizens, freemen and slaves, but made no distinctions on the basis of colour. The Ottoman empire likewise did not distinguish on the basis of race. Children from all over the empire were raised in the court to serve as soldiers and advisers.
Familiarity breeds…
The concepts that seem to be missing from your piece on interactive robots are “honeymoon” and “familiarity” (24 March, p 30). All the experiments it described aimed at assessing human reactions to “engaging” robots seem to be short-term: presenting the devices to conference delegates, for example, or gauging reactions from small groups of experimental volunteers.
When people meet interesting new people, the usual reactions are very similar to those described in the article: intrigue, fascination, a desire to know more and to know better 鈥� in short, a honeymoon period. Then, once complete familiarity with all aspects of the new individual’s personality has been established, reactions proceed through boredom and irritation to outright hostility.
If after a couple of years of working at my desk in front of the “expressive computer” RoCo, I drop my pencil on the floor, and yet again the screen 鈥� entirely predictably 鈥� bends forward to me, I may shout at it. It might take only a couple of further bursts of irritation before I started throwing my keyboard at the wretched thing.
All square
You illustrate a thruster array of a new engine for use in spacecraft with a square 46 脳 46 millimetres marked “1 kW”; a smaller square, 11.5 脳 11.5 mm, is marked “250 W”; the smallest, 4.6 mm to a side, reads “100 W” (24 March, p 43).
Since the power output will be directly proportional to the number of nano-thrusters, and thus to surface area, your two smaller squares should of course be 23 脳 23 mm and 14.5 脳 14.5 mm in size to give these power outputs.
Let’s have some fair play here. If a non-scientific publication had mixed up linear and square units in this way, Feedback would have had a field day.
鈥� Got us. Above, right, is the diagram in the proportions originally printed; and below that, with the proportions it should have had.
Climate challenges
You report that the Montreal protocol restricting ozone-destroying substances has had a bigger effect on reducing greenhouse warming than the Kyoto protocol can have, even if it is successful (10 March, p 6). James Hansen of NASA said something similar back in 2004.
He drew the obvious conclusion from this that perhaps we can achieve bigger reductions in greenhouse warming by dealing with greenhouse gases other than carbon dioxide, and that we can actually wind back global temperatures by making large cuts to methane emissions.
The biggest source of methane arising from human activity is livestock. We can gain some knowledge about the sincerity of climate scientists and politicians by asking how many are prepared to change their diet to save the planet.
In Australia, we have the highest ratio of cattle to people of any country on Earth. Calculated over 20 years, climate forcings due to methane exceed those caused by emissions from all our coal-fired power stations.
From Roger James
In Karl Popper’s philosophy of science, a hypothesis can never be proved, only disproved. As he put it, no number of sightings of white swans can prove the hypothesis that all swans are white, but the sighting of just one black swan can disprove it.
Given this, the scientist’s task is to be able to show that there are no established facts that are not compatible with a theory. The challenge for those who hold carbon dioxide responsible for climate change, therefore, is to ask what theoretically conceivable or possible observation would convince them that they are wrong. What would prove in their eyes that global warming is not caused by carbon dioxide emissions from human activity?
If they cannot come up with such a test, their theory lies outside science. If they can, it is up to us sceptics to shoot their theory down.
Portsmouth, Hampshire, UK
Wikid!
I am amazed that you should publish an interview with Jimmy Wales suggesting that Wikipedia was somehow entirely his creation (3 February, p 44). It is his co-founder Larry Sanger who is widely credited with bringing the wiki concept to the table, during the earlier Nupedia project.
Bioversity
You describe my colleague Cary Fowler as “an adviser to Biodiversity International” (17 March, p 50). Our correct name is Bioversity International.
Our initial focus, under the name International Board for Plant Genetic Resources, was on emergency collecting missions to deal with the threats Fowler helped draw attention to. Now we work to help poor farmers make use of agricultural biodiversity 鈥� plant and animal 鈥� to improve their livelihoods.
Wrong kind of theatre
May I point out some confusion in your report on the acoustics of “Greek amphitheatres” (17 March, p 19)? Theatres of the sort described and illustrated in the article are a Greek development and were intended for drama at religious festivals. Amphitheatres were a Roman adaptation of the theatre 鈥� put simply, two theatres joined together 鈥� for a range of often gruesome activities.
We have little evidence of theatres around 1500 BC. The early theatre of Dionysus on the slopes of the Acropolis in Athens seems to have had wooden benches until at least the late 6th century BC.
The white plague
Debora MacKenzie’s warning about extremely drug-resistant tuberculosis is timely (24 March, p 44). One of the problems we face in the UK is that almost all the doctors and nurses with practical experience of the disease have retired. What’s more, the surveillance system has been dismantled and the sanatoria sold for executive housing.
Few members of the general public have any idea of the danger we face. When we go to the opera and have a quiet sob at the deaths of Mimi in La Boh猫me or Violetta in La Traviata, we should remember that these tales were based upon the lives of real people whose names are known.
One of my great-grandfathers died of TB in 1877. He had by then infected my paternal grandfather, who left Scotland and subsequently infected his wife and both his daughters.
All of them died in Manchester between 1910 and 1921. Fortunately my father escaped infection, otherwise I would not be here to tell the tale.
In the late 1950s I worked in a hospital where we investigated cases of suspected TB in the Royal Air Force. We had plenty of work because infection was quite common in the general public, and when conscripted airmen were put together in a barrack block it soon spread. At least there was the medical back-up in those days to detect the infection and treat it.
The other blunder that we have made is that the public and clinicians alike have developed a distaste for autopsies, so many who die with TB must go to their graves undiagnosed, possibly having infected their relatives and carers.
All patients dying with a lung shadow that has not been positively identified should be subjected to post-mortem examination, not for curiosity but for reasons of public health.
Skin blindness
It is interesting that in the same issue that you publish an article on the origins of prejudice (17 March, p 40) you also have a brief item on oxytocin as an “insight hormone”, suggesting it as a treatment for people with autism, to help with emotional recognition (p 19).
Someone with the autism-spectrum Asperger’s syndrome once explained to me that he didn’t see people as “faces” at all, but as “brains”. He was unable to tell me which of two classmates had achieved something notable; he was aware only that they were both people he liked and what they were interested in. One was very tall and very black, and the other was a very slight blonde.
While it might make life more comfortable for those around him if he were treated to improve his emotional recognition, surely this is the exact opposite of what we need to reduce prejudice in the world?
No quantum holiday
Your introduction to Marcus Chown’s discussion of the illusion of reality in a quantum world helped propagate common and unnecessary misunderstandings (17 March, p 36). It suggested that quantum mechanics allows objects (such as an office worker) to be in a superposition of being in two places at once 鈥� such as the office and the beach.
For quantum mechanics to kick in, there must be no evidence that would allow anyone to figure out where the worker actually was. This means no tan, no memories of having been either on the beach or in the office, and not a single piece of paper shuffled on the office desk. Quantum trickery of this sort is a bad idea from the worker’s perspective: not only will she not have any memories of a relaxing day spent sunbathing, she will also not have any work to show for a day at the office.
Failure to appreciate these limitations of quantum superpositions is not trivial. It has given rise to numerous misleading claims. One example is the often-heard statement that quantum computers will be able to perform calculations on all possible inputs at once, which is not generally true.
The treacle box
Reading yet another reference to the Schr枚dinger’s cat thought experiment, I am prompted to write about an alternative case, which I have been unable to resolve.
Consider a box containing, rather than a bottle of poison and a cat, a bottle of viscous liquid and a shallow ramp. The decay of a radioactive atom causes the bottle to be broken, allowing the liquid to run down the ramp. Previous tests have shown that the liquid takes half an hour to do so, whereupon it drips out of the bottom of the box. Until an observation is made, the liquid is in a superposition of states: it is and is not running down the ramp.
Prepare the system, and make an observation half an hour later. If no liquid is dripping out, the atom did not decay; if it is, the atom did decay. In the latter case, the liquid has been running down the ramp for the previous half hour, confirming that the decay occurred, but unobserved.
But the argument goes that the act of observation collapses the wave function to determine which of the possibilities has happened. So has the liquid instead run down the ramp in the instant of observation?
I give up. Can some clear-thinking physicist please explain this?