Comebacks on the bouncing black holes (1)
In his book extract, Carlo Rovelli hits a good note on black holes (31 October, p 30). A true singularity predicted to have an infinite density at an infinitesimal point is a mathematical anomaly, as maths hates infinities. But here this one has sat, grinning wide 鈥� or the inverse thereof, in fact.
My only problem, though, is that when Rovelli’s black hole rebounds to become a white hole, tens of billions of years will have passed to those on the outside, due to “the dilation of time… in the rest of the universe”. This is a problem because, over this period, trillions of tonnes of material will fall in, past the event horizon. The effect of this raining down on the rebounding black hole must be addressed. I commend Rovelli for this innovative reassessment, however.
Comebacks on the bouncing black holes (2)
Stephen Hawking made a big splash when he forecast Hawking radiation coming out of black holes in such a way that, over time, a black hole could evaporate. Rovelli makes no mention of Hawking radiation in the extract from his book. Is Hawking radiation now dead in the water, being replaced with a more dramatic white hole?
Lockdowns may be a failure of Joe Public
To say “lockdowns are an indication of government failure” is disingenuous (Leader, 7 November). The real problem is that many citizens are unable to follow the guidelines, particularly among the 18 to 29 age group.
Other than countries that are very small, have low population densities or are so totalitarian that they pay no heed to citizens’ rights, I can see no nation that has got it “right”, but instead plenty 鈥� including the UK 鈥� that have given it a good shot.
Don't lump us all in with the US anti-vaxxers
You report that, if a covid-19 vaccine does arrive and is made available at no cost, 54 per cent of people polled in the US will refuse it (31 October, p 8). Across the border in Canada, we do have anti-vaccination activists, but far fewer than in the US.
In Ontario, Canada’s most populous province, take-up of the 2020 flu vaccine has already been much higher than a “normal” year this early in the season. Canadians’ willingness to be vaccinated differs markedly from our US neighbours.
My quick personal guide to virus exposure risks
I tried to give my family a numeric guide to risk for coronavirus exposure to help them figure out which activities were riskier (24 October, p 40). It is my attempt to quantify exposure risk guidance from the US Centers for Disease Control and Prevention.
Give yourself a score for the following five factors. 1. Time 鈥� one point for every 15 minutes of exposure. 2. Mask 鈥� one point for a mask, two points for no mask. 3. Groups 鈥� one point if one to 10 people are present, plus an extra point for every further group of one to 10 people. 4. Breath rate 鈥� one point for talking, three for protests, five for running. 5. Location 鈥� one point for outside, two for inside at 2 metres apart. Finally, multiply the scores.
Example 1: you are talking outside with a friend for 15 minutes or less, with a mask, in a group of one to 10 people. This gives 1 脳 1 脳 1 脳 1 脳 1 = 1. Example 2: you are protesting for an hour outside with 100 people, half of whom are wearing masks, giving 4 脳 1.5 脳 10 脳 3 脳 1 = 180 points.
The lower your points, the lower your risk. I am a climatologist, so while I know a bit about probability and risk, I don’t know enough to understand the factors of covid-19, which is why I kept this to virus exposure only.
Bean counters are to blame for this rat's nest
As a retired IT professional, I recognised only too clearly the problems with legacy systems described in the article “Code red” (7 November, p 44).
Computer systems have a life in the same way that vehicles do. We replace cars and lorries regularly to pre-empt serious issues, so why not do the same with computer systems? Invariably, the overriding cause of the rat’s nest you discuss is short-term cost-cutting and a refusal to invest in preventative maintenance and upgrading or replacement until it is too late.
There is a better way to green our economies
Your excellent article on the rewiring of economics after covid-19 drips with hope and the promise of fresh thinking, particularly on the climate and monetary fairness (31 October, p 36). Among the big ideas, however, there was a notable absentee.
Last year, many economists signed a letter printed in that called for something called Carbon Fee and Dividend (CFD). It is a simple idea: importers and extractors of fossil fuels pay a levy by the tonne, at a rate that rises over time. The money raised becomes a monthly dividend paid to every citizen.
People would then have extra money to cope with price rises that CFD may cause. It is estimated that 70 per cent of us would be better off, with only wealthier high-consumers needing to adapt their habits to avoid losing out.
I have yet to hear of another scheme that can reduce emissions and inequality so elegantly, improving environmental and health outcomes and deftly avoiding the risks of economic pain and public backlash.
Seeing the light: is this the real cause of ball lightning?
Your article on ball lightning failed to mention another possible cause: induced hallucination (24 October, p 46). This was discussed in earlier coverage (22 May 2010).
I suspect that the impact of a bright flash on vision could be enough to trigger the illusion. Recall how apparent reports say the glowing ball follows the person’s gaze and has no physical manifestations like heat or odour. This seems more likely than extra-dimensional wormholes.
Incarcerated, yes, but free to choose to fight fires
Your review of sci-fi thriller The Book of Malachi mentions that inmates in the US are “used as firefighters” (17 October, p 32). However, I would like to point out that this is a that prisoners must earn a place in.