Editor's pick: Do we already know this treatment is safe?
Helen Phillips describes the use of propranolol to alleviate the terrifying flashbacks of post-traumatic stress disorder (4 February, p 36). Propranolol was discovered in 1964 and is on the World Health Organization's List of Essential Medicines. It has since been used to continuously treat millions for high blood pressure. There must be many thousands of people who have avoided PTSD and so been spared terrifying flashbacks by being on it while experiencing or recalling trauma.
A study comparing the incidence of PTSD in those on propranolol with a control population is surely needed.
Editor's pick: Do we already know this treatment is safe?
Phillips describes the use of drugs that inhibit protein synthesis – including propranolol – in treating PTSD. I am concerned that they may not only alleviate traumatic memories, but also cause the loss of other memories that are recalled while the drug is still having its effect.
It is vital that we consider any such possible effects before rolling out the treatment.
Time, gentlepersons, please, time please
Anil Ananthaswamy discusses the fundamental make-up of things and the role of time (4 February, p 28). I suggest it would be easier for physicists to resolve the riddle of time if they moved from the abstract to focusing on how we define the passage of time in real life. Independent physicist Julian Barbour's approach to time comes closest to this.
A period of time is nothing more than the ratio of distances covered by reference objects. Measuring a pulse at 72 beats per minute is shorthand for saying that heart muscles contracted by, say, 5 millimetres 72 times while a watch escapement moved, say, 12 millimetres 60 times. The concept is the same if the ratio involves vibrating caesium atoms.
This model works fine until we approach extremes. At the sub-atomic level, the smallest distance is the Planck length and with nothing smaller to reference against, time as a comparison of changes in distance vanishes.
Similarly, at relativistic speeds the distance a grandfather clock pendulum swings, for instance, foreshortens, so that if it moves 150 millimetres per second when the clock is at rest, it will appear to approach 0 mm per second when it's in a spaceship approaching the speed of light.
Time, gentlepersons, please, time please
You offered quick summaries of current ideas about what time is. These left me with a question.
If, for example, time is caused by increasing entropy or disorder, this raises the same problem as does the approach in quantum mechanics that “Time… just is” – in which an allegorical clock is required outside of the system in question, even if that system is the entire universe. That is, how would any local collection of particles be affected by remote ones to obey the arrow of time set by the overall system?
Consider knocking snooker balls around a table from a non-random configuration such as a line. Barring a statistical fluke, the resulting pattern of balls would soon appear much more random even though each constituent knock would, according to standard mechanics, be time-reversible. Increasing entropy is an understandable result of individually time-reversible interactions, but I want more explanation of how increasing entropy of the system can cause the direction of time.
Time, gentlepersons, please, time please
Ananthaswamy's excellent article reminded me of work by physicist on the . Swingle has that black holes must represent Nature's most efficient quantum computers. This, with the “holographic principle” that a 3-dimensional universe maps on to a surface, raises the distinct and disturbing possibility that we really do live in a computer simulation, running on the event horizon of a black hole.
First class post
Dreadful. Corals are the canary in the coalmine for this planet
Kit Drake to our report of an unprecedented fourth year of coral bleaching (25 February, p 6)
The meaning of life is what we choose
Teal Burrell discusses the benefits of a sense of purpose and the meaning of life (28 January, p 30). Arguably the only scientifically demonstrable “purpose” for life is to reproduce itself and sometimes help that new life survive to reproduce in turn.
For humans, the only “purpose” or “meaning” for life is what we choose to bring to it.
For some this is crushing banality, but for others it sets them free. I choose the latter.
Cholesterol correlation can't prove causation
Michael Brooks quotes Rory Collins of the Cholesterol Treatment Trialists' Collaboration suggesting that cholesterol deniers are akin to those who believe in a flat Earth (11 February, p 28). Collins argues that “lifestyle factors don't matter, as long as you bring your cholesterol levels down” and that “statins reduce the risk of coronary heart disease in direct proportion to the reduction in LDL-cholesterol.”
Statins bring down cholesterol, and the more you take the more it comes down. Statins also reduce cardiac risk, though not a lot. But that doesn't prove that lower cholesterol reduces cardiac risk. There is . Lower cholesterol while on statins may merely be a marker that you are taking the statin: inflammation may be the risk for the heart.
The Avandia story is more complicated…
Your leader article on access to drug trial data snipes at Avandia, used to treat type 2 diabetes (11 February, p 3). I worked for GlaxoSmithKline on drug discovery from 1974 to 2001, where my first boss led the team that discovered rosiglitazone (BRL49653/Avandia), although I wasn't on that team.
It is true that GlaxoSmithKline was fined for withholding clinical data on Avandia. But in 2013 the US Food and Drug administration, unlike the European Medicines Agency, withdrew restrictions on the marketing of Avandia, after a review of all clinical data. You could at least have mentioned that its risks relative to its benefits are a controversial subject.
Hexamethylbenzene dication follows the rules
You report a compound in which a carbon atom bonds to six other atoms (14 January, p 16). Making this hexamethylbenzene dication and determining its structure are interesting and praiseworthy achievements.
But to explain the bonding in this substance doesn't require us to rip up any chemistry textbook. Just turn back to a preceding chapter, describing how boron forms a family of compounds in which there aren't enough electrons to hold all the atoms together by conventional electron-pair bonds. Instead, the atoms are arranged at the corners of polyhedral clusters, and the electrons are delocalised over the whole structure.
The rules of structure and bonding in boron clusters and related compounds were put forward about 50 years ago by the late of Durham University, UK, and the reported compound obeys them very nicely, as the authors of on it acknowledge.
How hydrogen got into Earth's mantle
Andy Coghlan says “deep inside the hot mantle, the conditions are right for chemical reactions to turn hydrogen and rock into water” (4 February, p 12). That may well be, but where does the hydrogen come from?
The editor writes:
• We assume it has been there since Earth formed from the solar nebula.
Wood house cooling and the garden bonfire risk
The climate benefits of wood-burning stoves are even more dubious than Michael Le Page suggests (4 February, p 22). Many draw the air for combustion from the room in which they are installed. So cold air is drawn into the house, increasing the amount of energy required to heat it.
Sitting in a “cosy” pub next to a very hot radiator while having my feet cut off by the icy gale heading for a roaring log fire intuitively supports this.
If you must buy a wood-burner, get one that draws its combustion air from outside.
Wood house cooling and the garden bonfire risk
Le Page refers to a 2010 analysis of particulate pollution that found up to 10 per cent of London's wintertime air pollution came from wood. A , also by environmental scientist Gary Fuller and his team, found little correlation between pollution and daily mean temperature. Instead, wood pollution levels peaked on weekend evenings and school holidays. Fuller interpreted this as resulting from open fires being used as a “decorative or secondary heating source”. An equally likely cause is weekend gardeners burning woody waste, and Fuller accepted that such smoke contributes to summertime particulate pollution.
Animal magnetism may work both ways
Henry Nicholls says red foxes apply a magnetic sense to hunting and are more successful when they pounce in a north-easterly direction (17/24/31 December, p 44). Perhaps the prey, distracted by their own magnetic sense, are often facing away from the fox?
That metaphor is out of the League
I am flummoxed by a rugby ball as an analogy for the shape of Earth (11 February, p 40). I visualise Earth – 21 kilometres longer at the equator than at the poles – more like a hole-less doughnut.
For the record
• Ill effects of statins include 1 in 10 experiencing muscle damage and 1 in 50 diabetes (11 February, p 28).