Symbiosis makes life's origins even more complex (1)
I enjoyed Rowan Hooper’s revisitation of the great origins-of-life theories, in particular Freeman Dyson’s idea that biochemistry preceded cell biology on the primordial Earth. A key component of Lynn Margulis’s endosymbiosis model was the acquisition of photosynthetic bacteria by proto-cells, making it possible for plant cells to fix carbon into glucose (30 May, p 40).
Of course, in deep-sea hydrothermal vents, the lack of light makes photosynthesis impossible. So, the archaeal species there use chemosynthesis, by which electrons from dissolved hydrogen sulphide gas are used instead of water to turn carbon dioxide to glucose, gleaning a sulphur by-product instead of oxygen. Whenever migration to a light-rich surface was feasible, perhaps photosynthesis evolutionarily succeeded chemosynthesis, enriching our atmosphere with oxygen.
Symbiosis makes life's origins even more complex (2)
Hooper’s article suggests that life may be similar wherever it arises. Other pieces in 快猫短视频 have concluded that there was a single origin of life, and therefore a last universal common ancestor (LUCA). If life is similar wherever and whenever it arises, then perhaps there were several indistinguishable origins of life at different times and places on Earth, and LUCA may not have existed after all.
Save the world's coral reefs, don't resurrect them
Your look at coral regeneration projects states that rehabilitating just 10 per cent of the 11,700 square kilometres of coral reefs degraded between 2009 and 2018 could cost up to $17 trillion. Given that, at best, this would be only a partial, short-term mitigation, it would make more sense to apply such huge resources (if available!) to directly reducing or even reversing greenhouse gas emissions, thus benefiting even more than just coral reefs. As the article highlights, this is a clear case of prevention being better than cure (13 June, p 38).
Getting to TRAPPIST-1 is easier said than done
I see that Paul Bowden has planned out a journey to the TRAPPIST-1 system. If it were a round trip, it would take 15 years on board and 80 years on Earth. Paul doesn’t mention exotic sci-fi forms of propulsion, so I assume he envisages some sort of rocket motor capable of burning continuously for 15 years to provide his 1 g of acceleration (Letters, 6 June).
I can’t imagine how to calculate the mass of fuel that would be required or the size of the fuel tanks needed. The problem is that both quantities would be so enormous that the engines would need to be massively scaled up, with the consequence that ever more fuel would be needed. I think Paul has a long wait ahead of him.
Money may play a role in seasonal birth patterns
You report that births in the UK followed seasonal patterns for much of the 20th century, peaking in the spring. But I think one main factor may have been omitted: the tax rules at that time (23 May, p 4).
My parents got married at the beginning of April 1948. At that time, the man would receive the married man’s tax allowance for the entire year in which they were wed; therefore, they were incentivised to marry before the start of the new tax year a bit later in April. This, as I understood from my parents, was very common and obviously resulted in more babies being born nine months to a year later, in spring.
Have you tried turning it off and on again?
快猫短视频 often reminds us of the potential damage from large space storms. But far less extreme solar and power grid phenomena can still wreak domestic havoc (6 June, p 14).
Take one occasion where my dishwasher failed to empty, for example. I could find no blockage. Then I realised that flickering lights in my study probably signified an electrical issue caused by a coronal mass ejection at the time. On a hunch, I pulled out the dishwasher, crawled behind it and turned the power off and back on. It has worked properly ever since.
What's in a name? For fields, quite a lot
The article about fields reminded me of my undergraduate days. When Chanda Prescod-Weinstein writes that a field is a mathematical relation that “assigns a number to each point in space and time”, she is, of course, correct. Novice electrical engineers were expected to accept this as a matter of faith, something I found challenging (23 May, p 17).
Ultimately, the problem is that we use the word “field” to mean the abstract, conceptual-world representation of something to which we also give the name “field.” A description in the conceptual world cannot influence the path of a particle, and cannot be measured. But an electric or magnetic field can most certainly change the motion of a particle, and can be measured.
As a metrologist, I would say that a “field” is something that exists in space and time, and affects things in the real world. It is unfortunate that we use the same word to name its mathematical model in the conceptual world.
More theories on why T. rex had tiny arms (1)
Aren’t T. rex’s small arms a question of balance? A bipedal theropod would have balanced over its hip joints. If its skull was enlarging due to evolutionary pressure, as described, then this increased mass would be counterbalanced by a heavier or longer tail. The evolution of lighter arms would keep the increasing weight of its front half to a minimum. Arms would still be very useful but the optimal size smaller (30 May, p 17).
More theories on why T. rex had tiny arms (2)
T. rex developed these features for deception, so as to look relatively 鈥榓rmless.
For the record
Paul Erd艖s conjectured that the maximum number of connections in the planar unit distance problem would grow only slightly larger than the number of points, as you added more points to the grid (30 May, p 6).