Late light licked?
In “The light that came late” (15 August, p 26) Anil Ananthaswamy cites esoteric theories based on string theory and quantum gravity to explain why high-energy photons from extremely distant gamma-ray bursts appear to arrive later than lower-energy photons produced in the same event. I would suggest a simpler explanation for this phenomenon: optical dispersion.
Space, even intergalactic space, is not a pure vacuum but is reckoned to contain an extremely tenuous and largely ionised gas. Over vast distances, this could slow down the high-energy “blue” light significantly more than the low-energy “red” wavelengths, giving rise to the time differences measured.
On Earth, this is the same phenomenon that leads to refraction of light into its various colours, the product of which is rainbows. Has this possibility been considered on a cosmological scale?
The editor writes:
鈥� The possibility has been considered. Gamma rays can be deflected by interactions with intergalactic matter, but in a fundamentally different way to the refraction that occurs in a prism or in Earth’s atmosphere. Lower-energy rays are affected more, which would lead to a delay effect precisely opposite to that observed. The cumulative effect of such deflections is expected to be much less than the magnitude of the observed effect.
War and weaponry
I agree with Cedric Griffiths (22 August, p 24), Frank Jackson and Peggy Conroy (25 July, p 26) that war is significantly driven by the profit motive. But unlike Griffiths, I can only imagine captains of industry uttering hypocritical oaths, rather than the Hippocratic ones he suggests. Indeed, a “do no harm” law would surely just enrich the already amply paid legal profession.
Instead, we need targeted taxes. These will inevitably get industry’s attention, if only to seek avoidance strategies. Taxing war could lead to some complex legal penmanship, but the first step is clear: tax carbon, so at least they damage our ecosystem less in the process.
However, historically warfare’s main effect has been a lessening of the human population. In this case, we should tax modern warfare’s efficiency in this “key performance indicator”. How to go about doing this I will leave to other minds than my own.
From Martin Gregorie
Unlike Nicholas Macy, I can think of several devices that were designed, built and first used in war (29 August, p 26): all explosive ordnance, including shells, bombs, grenades, landmines and torpedoes. Many of these have subsequently been adapted for other purposes, such as the use of torpedoes for oceanic exploration.
I must also counter his assertion that nobody thought of other uses for atomic weapons. , which ran from 1957 to 1973, conducted 27 tests involving 35 nuclear charges to investigate the use of atomic explosions for civilian construction purposes, such as excavating canals and passes, and building hydroelectric dams.
There was also , which investigated using atomic bombs to propel spacecraft.
Harlow, Essex, UK
Restored waves
Andy Howse suggests that sea waves lose energy because they have to lift the water against the force of gravity (8 August, p 25).
All mechanical waves involve an interaction between the inertia of the supporting medium and the restoring force particular to that wave; in this case, by the rise of the water surface. Waves transport energy through motion (kinetic) and energy of work done against the restoring force (potential).
At any one position, energy is continuously exchanged between these two forms as the wave passes. The storage (not loss) of potential energy as the sea surface rises is essential for wave motion to occur.
In deep water, wave energy is dissipated into heat by viscous stresses as the waves interact and water mixes, and to a small degree by turbulence in the white tops. In shallow water, energy is predominantly dissipated into heat by the friction between the wave motion and the seabed. When a wave breaks, energy is further dissipated by the viscous stresses in the turbulent flow and by work done in disturbing the seabed.
Can't run from DNA
We read Katrina Voss’s article on open access to genomic information (22 August, p 22) with great interest. Summing up her argument, she quotes her father: “I’m not worried, I’m just not that important.”
Narcissists aside, we can all agree that we aren’t that important to the rest of the world. However, what Voss fails to account for is the small cadre of people to whom we are that important. This set includes friends, relatives, employers, potential mates, and even stalkers who already look at the wealth of information available online.
One instance where this data could be misused would be by adopted children, or even the children of sperm donors, to find parents who might not want to be found.
Similarly, certain professions could be affected from the outset. Genomics has the potential to touch all aspects of sport, from using genetic information for draft picks, to mandatory genetic testing to screen out players at all levels of the game at risk of serious and unanticipated ailments.
With the growth in understanding the links between athleticism and genetics, public disclosure of personal genomic information of athletes may be just a logical extension of what is already in place. Analysing how athletes deal with this new form of personal information will be of particular interest to the rest of society as it learns how to manage the eventual disclosure of personal physical and genetic information.
Allergic, not nuts
Rosemary Bentley suggests that a substantial degree of confusion exists over whether a peanut allergy also extends to nuts (29 August, p 26).
Although I do not suffer from peanut allergy myself, I work with a large number of people who do. While it is correct to say that some are unsure whether they also have a nut allergy and avoid anything which displays a “may contain nuts” warning, a good 75 per cent suffer from both. There is not necessarily a correlation between the two, but given the severity of allergic reactions, no one can be criticised for playing safe.
Common ideal
I agree with Mark van Vugt’s well-reasoned, sensible and logical proposals for overcoming the environmental tragedy of the commons by everyone working together (22 August, p 40), but I doubt that this will spontaneously happen within the few short years we have left before we become overwhelmed with tipping points.
I can only assume that van Vugt’s experimental subjects, whose responses support his optimistic view, all come from the rarified world of academia. What is clear to me is that none of his wonderful conclusions could possibly have derived from the overwhelming majority of humans. Out here in harsh reality, genteel persuasion is not feasible when facing food wars, oil wars and 鈥� very soon I predict 鈥� global water wars.
The only solution is a globally organised imposition of fairness and propriety. Unless we agree to allowing such impositions, I doubt if humanity will survive long enough for van Vugt’s idealism to be realised.
Warming wobble
On re-reading Anil Ananthaswamy’s article on melting Arctic ice caps (4 July, p 28), I realise I haven’t seen any mention of the Earth’s rotation in connection with global warming. If a mass of meltwater sufficient to raise global sea levels by several metres spreads out from within 1600 kilometres of the Earth’s axis of rotation towards equatorial regions, about 5000 km further out, where the rotational speed is roughly 1600 km/hour, this could have a significant braking effect on rotation.
The loss of icy mass from Antarctica will also reduce its balancing effect on the northern hemisphere’s continental masses. What will be the effect on the stability of the Earth’s rotation, and how might the rotational braking affect tectonic plates and volcanism? Is there anything in the geological record from other sudden changes in sea level to indicate how strong these effects will be?
Ain't got the guts
Rick Jefferys writes that “individuals can have significantly different gut flora and other digestive capacities” (15 August, p 22). A doctor told me of a patient aged about 50 who ate enormously and yet remained exceedingly thin. When he had his appendix removed, the surgeon had a routine look around inside the abdomen, and discovered that his small intestine was only 1.5 metres long instead of the normal 7 metres.
This would indeed have a significant effect on the proportion of calories absorbed.
Mystical roots
I must agree with Perry Bebbington in supporting your coverage of cold fusion (5 September, p 27). Much of chemical practice arose from the alchemical search for a “universal solvent” and the philosopher’s stone. Astronomy has its roots in astrology 鈥� one could go on.
The true opponents of progress are conservatives who fight tooth and nail against new ideas, only to end up declaring “of course, it was my idea all along”.
Nose-picking licked
What makes Sophia Dunn think that hoofed animals do not pick their noses (5 September, p 26)? Cows do it all the time 鈥� with their tongues.
For the record
鈥� The research into the effects of railway privatisation in the UK was published in volume 60 of , p 355, not volume 63 (22 August, p 40).
鈥� The feature on other dimensions included a quote from Roger Penrose (29 August, p 34). The words are indeed Penrose’s but the book Gravitation in which they appeared was not written by him, as we stated, but by Charles W. Misner, Kip S. Thorne and John Archibald Wheeler.