On the move to LEDs to illuminate our cities (1)
Chanda Prescod-Weinstein laments the shift to broad-spectrum white LEDs in towns and cities because of the impact on the night sky. However, go to any sizeable theatre today and you will see from the stage lights that LEDs can be any colour. It isn’t obvious why most LED road lighting is white, and it isn’t certain that white is the best colour, at least for roads. (4 May, p 22)
In dim light, the human eye is more sensitive to a deep green colour, and it would be perfectly possible to make green LEDs for road lighting, though people might not like them in residential areas. While we have become used to the colour rendering of sodium street lights and the earlier mercury lights, the even older gas lights were actually greenish, due to the thorium in the “mantle”.
On the move to LEDs to illuminate our cities (2)
Prescod-Weinstein regrets that when street lighting was converted to LEDs there was no requirement that the white light be filtered to a single frequency, which would make it easier for astronomers to deal with.
But that would defeat the purpose of converting to LEDs 鈥� their efficiency. Filtering out most of the frequencies would drastically cut the amount of light produced per watt of power. Besides this, white light actually helps people to see things better at night, especially in their peripheral vision.
Plenty of progress needed to green global energy
In many countries, such as India, power generation is indeed moving noticeably away from fossil fuels, with significant reductions in carbon emissions for that sector. (4 May, p 8)
However, the overall energy consumption and carbon emissions of many nations is changing far more slowly, if at all, due to continued reliance on oil and gas for heating buildings and fuelling industrial processes 鈥� including plastics manufacture, as stated in another article in the same issue (p 13). And then there is transport, particularly kerosene-fuelled aviation, which is on the increase worldwide.
Are we in a cosmic hole of our own making? (1)
You report that we are roughly in the centre of a very rare void in the universe that doesn’t match our cosmological theories. What else seems to be vanishingly rare in our part of the universe, roughly in the centre of the void? Life. (20 April, p 36)
That is either an impressive coincidence or there is some cause and effect going on. Does the void make life more likely? Or maybe the seemingly unique existence of life on Earth could be generating an outward force of some sort, possibly through frequent collapse of quantum wave functions in our region, since there is more going on and more consciousness to force particular outcomes.
This would be very testable by comparing the velocities of galaxies within and adjacent to the void with those further afield to see if it continues to expand. You could then extrapolate back to see if this started when life emerged. Either way, maybe looking for voids could be a good way to understand where extraterrestrial life might exist.
Are we in a cosmic hole of our own making? (2)
Clearly, the reason that the Milky Way is near the centre of a cosmic void is that no other advanced life forms want to risk their worlds getting infected with Earth’s planet-destroying virus. They aren’t yet sure if it is catching, so they are keeping their distance.
Just so many sources of pollution to worry about
Thank you for the article on indoor climbing walls and the concerns about inhaling chemicals in the rubber dust released by the shoes used in such facilities. It was excellent, and this is something I have worried about for a while. (11 May, p 10)
In a similar vein, I also have concerns about possible pollution from the rubber that can be found in artificial turf used for playing fields and in gardens, where its use has become more popular because it is touted as low-maintenance and better for the environment because it uses less water.
Demonising plastic really isn't helpful
The statement that “plastic, rightly demonised as a scourge of the modern world, could be fantastic again” seems to go too far in its criticism of the material. (27 April, p 36)
It takes less energy to make a plastic bottle than a glass one. Additionally, plastic films play a crucial role in extending the shelf life of perishable foods, thus reducing food waste, which is a significant contributor to environmental degradation.
While advocating for increased plastic recycling and waste reduction is commendable, I urge against the oversimplification of this issue or resorting to sensationalist language. Demonising plastics does little to foster constructive dialogue or promote sustainable solutions.
Deluges could bring a climate change gain
The increasing frequency of heavy rainfall events in the United Arab Emirates 鈥� like the one we saw recently, probably driven to some extent by rapid climate change 鈥� may reduce dependence on energy-intensive desalination, which is currently a key source of drinking water in the region. (27 April, p 16)
Interconnected underground tanks could possibly store runoff in the cities, greatly reducing the problem of flooding, and with filtration and purification, become an intermittent source of drinking water at low energy cost.
Damned if you do, damned if you don't
If you eat meat, researcher Anthony Hulbert recommends you have grass-fed beef or lamb and wild-caught fish, as they are high in omega-3s, and avoid pork and chicken because they are high in omega-6s. I rarely eat fish as I don’t want to contribute to the destruction of aquatic wildlife, and I avoid beef and lamb 鈥� due to their larger carbon footprints 鈥� in favour of pork and chicken. It seems that you can eat to help the planet or eat to help your health, but not both. (27 April, p 40)