Editor's pick – Pedestrian-friendly cities need room to play too (1)
Researchers in Canada and the US find that grid street layouts encourage people to walk rather than drive, unlike those dominated by cul-de-sacs, Alice Klein reports (21/28 December 2019, p 10). There are more factors to consider. In the report that I co-wrote 鈥� 鈥� we estimate that if a housing area contains 100 children and roads that are safe enough for them to play outside, they will make around 280,000 journeys per year on foot. Not only is this free exercise, but a lot of vehicle pollution is avoided.
The domination of the car prevents children from playing freely, an essential part of their physical and social development. They still do play out in cul-de-sacs and where there are measures to slow traffic: parents permit this because the roads are safe. Grid layouts are more dangerous, and parents understandably keep their children indoors, condemning them to increased obesity and stress.
Editor's pick – Pedestrian-friendly cities need room to play too (2)
This finding made me think of three UK towns: Colchester in Essex, where I grew up, Diss in Norfolk, where I worked for many years, and Towcester in Northamptonshire, which I visit. In all, residential areas laid out in the years after 1945 have curvy streets with cul-de-sacs.
Most of these, though, are connected by footpaths, often only 1 or 2 metres in width and ideally suited to pedestrians. So the walking route between points up to a half-hour’s walk apart is very nearly a straight line, while the driving route may be as much as five times that distance. Pedestrian access to public transport is a red herring in the many places where there are now no buses.
As for cycling, the main problem in the UK is the weather. If you commute by bike, you really need a shower and clothes storage at your place of work. Planners could insist on this, in the same way as they often insist on off-street car parking for new business developments.
Some things we should learn about roundabouts
Richard Webb rightly extols the virtues of roundabouts and identifies problems implementing them in the US (21/28 December 2019, p 65). There is also great scope for improvement on the way they are laid out in the UK. I do suspect that our Department of Transport may be as intransigent as the US authorities.
I am thinking of a that allows safe, low-speed entry and exit in all traffic conditions for all vehicles, including articulated bendy buses, with high traffic flows. This is achieved by slight curves to the arms, each a single carriageway just wide enough for bus wheels. Yellow zebra pedestrian crossings on each arm remind drivers that they don’t have priority under Swiss law and offer easy and safe passage for walkers and cyclists. In the UK, anyone crossing the arm of a roundabout is likely to be intimidated by speeding drivers, in part because it unnecessarily has two lanes.
All parties in the UK’s recent election promised to promote cycling and walking for health and climate change advantage. That will be impossible unless we learn from the Swiss, not only on roundabouts, but more generally on road and path design.
What more can the aviation industry do?
What more could the aviation industry do to reduce carbon emissions? The decision by Airbus to stop making the double-decker A380 in 2021 may need to be reviewed (11 January, p 18). This plane, particularly if configured with all seats in economy for intercontinental travel, has higher efficiency in terms of fuel used per passenger per kilometre than others.
Incorporating railway stations into more airport passenger terminals would help reverse the current trend of scheduling hundreds of flights between regional airports, which may be convenient, but is more unkind to the environment than doing a final leg by train.
A jet engine’s maximum efficiency is at high throttle settings. So can we design a plane with booster engines used only for take-off, with more modest engines for cruising flight?
Running big engines for the entire flight is an absurd waste of kerosene and an abuse of the atmosphere. Clearly a new design of aircraft would be needed to stop the drag of extra engines ruining the economy gains of the concept.
Vacuum airship plan faces an uphill battle
The article on vacuum lift airships by Philip Ball was, in a manner of speaking, a gas (21/28 December 2019, p 68). But some aspects of the idea sound like so much hot air. The greater lift that a vacuum gives compared to the same volume of hydrogen or helium must be greatly outweighed by the weight of the structure needed to contain that vacuum. A container evacuated of air produces lift of 1.28 kilograms per cubic metre, which is only 0.09 kg/m3 more than hydrogen offers.
So it seems to me that this idea will not get off the ground using current materials.
More thoughts about metallic hydrogen (1)
Michael Brooks makes the case for hydrogen existing as a metal by pointing out its position in the periodic table at the head of the group of alkali metals (4 January, p 43).
All elements in this column have a single valence, or outer shell, electron. When this is delocalised and produces electrical conductivity in an alkali metal, there are still electrons in inner shells around the nucleus. This means a stable metallic lattice can form.
Hydrogen, which has only one electron, would be left with a naked proton, so a stable lattice would be much harder to form.
We can also put this element on the other side of the periodic table, at the top of the group of non-metallic elements that require just a single electron to form a complete outer electron “shell” 鈥� the halogens.
Metallic hydrogen may be as unusual as a G-clamp with a left-hand thread, as shown in the illustration with the article.
More thoughts about metallic hydrogen (2)
If metallic hydrogen were a room-temperature superconductor, experiments on it might produce useful information. But, given the enormous pressures that seem to be required to keep it metallic, it surely isn’t practically useful.
A thought occurs to me: have any of the teams doing these experiments considered using pure deuterium, an isotope of hydrogen? I suspect that the pressure required to might be significantly lower. It would pretty certainly still be much too high for practical applications, but possibly easier to experiment on.
As a community we must choose our words carefully
I know what you mean when you write that there is no such thing as scientific truth 鈥� only successive attempts to get closer to it (Leader, 14 December 2019). So, I think, will most 快猫短视频 readers. But be careful what you write. There are truth corrupters out there who will deliberately misrepresent, cherry-pick, and take words out of context.
Creationists, climate change denialists and anti-vaccination activists can, and probably will, seize upon such quotations in an attempt to discredit science and bolster their absurd claims.
Their lies cause harm. Thousands who could and should have been vaccinated against diseases such as measles have died. By 2100, multiple and complex climate change impacts will force the relocation of hundreds of millions of people 鈥� a potentially avoidable disaster.
As a scientific community we must choose our words very carefully and deter cherry-picking.
Practicalities of taking back control of our deaths (1)
Bryn Glover wonders why legislation can’t allow for burial of the dead on private land such as gardens (Letters, 14 December 2019). I think each local authority can permit this.
When a friend recently died in Gloucestershire, his relatives applied to their council to bury him in their garden. The council appeared flummoxed by the request. When the relatives said that their religion insisted on burial within 24 hours, the council quickly and graciously agreed it.
Practicalities of taking back control of our deaths (2)
It is already legal in the UK to bury loved ones in private gardens, subject to certain permissions and to regulations concerning depth, distance from buildings, and so on. Problems arise when the time comes for the survivors to move house. The emotional wrench of leaving not only a home but also a dead spouse is considerable. New buyers may not always appreciate having a body in the garden.
A burial at sea may be an option that would better suit Glover.
But the human mind/brain is deterministic
Sam Edge mentions the common assumption that conscious entities such as human minds are self-causal and non-deterministic (Letters, 4 January). Of course, like everything else in the universe, our mind/brain is deterministic, if you accept that every event has a reason or cause.
We can’t mechanistically predict what someone will think about anything because of the brain’s complexity 鈥� it has 86 billion neurons and a quadrillion synapses 鈥� and also because of the environmental, physical and cultural influences which affect our thinking.
If a machine could do all that, it would in effect be a human, and why would we want to create another one of them when we have 7.8 billion already?
Do students seek long-term relationships?
The dating service Tinder doesn’t seem to be as good at finding you a partner as you might think, according to a study that found only 25 per cent of participants reported using it to find someone interested in a long-term relationship (7 December 2019, p 15). This sounds damning, until you read that the study subjects were all university students. It may equally be a proof that only 25 per cent of university students are looking for a long-term relationship.
I met my wife on Tinder, in my 40s. Before I met her, I went on many other dates from Tinder, all in my age range and all looking for a serious relationship. This study may say more about our reliance on students as study subjects than about anything else.
When a game solves an impossible problem
Jacob Aron has been playing the game Death Stranding, in which you must carefully choose your route or die (14 December 2019, p 32). Has he unwittingly been drawn into a vast data accumulation programme that an artificial intelligence can eventually use as a data set for solving the currently intractable travelling salesman problem?
For the record 鈥� 25 January 2020
鈥� We misnamed a dog breed on our chart showing their sizes and life expectancies: it is a Bernese Mountain dog (4 January, p 38).
鈥� It is the nerves within the clitoris that are rarely depicted or described in textbooks (4 January, p 12).