When the Earth first formed into a solid sphere with an atmosphere, that atmosphere was deficient in oxygen. The question of when and how the planet became oxygen rich is an interesting and important one and recent research challenges some old ideas about the earliest appearance of oxygen.

The “Great Oxygenation Event” that infused the gas into our atmosphere is commonly thought to have occurred around 2.4 billion years ago, when a rise in cyanobacteria released a huge amount of oxygen through photosynthesis. But it’s been difficult to get any more precise in terms of dating the first appearance of this life-giving gas; after all, how are scientists supposed to detect such a small quantity of oxygen from so long ago?
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On March 11, 2020, the World Health Organization declared Covid-19 to be a global pandemic. In the two years since then, we have passed one grim milestone after another. As of yesterday, there have been 483 million cases worldwide or 6.1% of the total population of 7.9 billion. There have been a total of 6.2 million deaths.

When one looks at the per capita death rates, apart from Peru (which has the highest rate), Brazil, and Chile, the rest of the top 20 countries for cases are in Europe or the US. In fact, the highest ranking country outside Europe and the Americas is at #35 with Tunisia. A similar pattern holds for infection rates.
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The covid-19 pandemic is going to be a rich source of data for how to deal with any future pandemics. The prevalence and degree of severity of the disease has varied widely across the globe, as have the ways in which various countries responded to it, and this has given rise to so-called ‘natural experiments’, those in which one can isolate and study the effects of individual factors without having to actually do experiments.

One of the firmest lessons is the importance of vaccinations for everyone but especially the need to vaccinate those segments of the population that are most likely to suffer adverse effects and death. In the case of covid-19, it was the elderly and the immunocompromised who were most at risk.

But there is also the question of how far to go with trying to isolate regions in order to keep the virus out of the country. The countries that practiced severe lockdowns and strict border controls (such as China, New Zealand, and Hong Kong) were initially able to keep the numbers extremely low while many other countries were suffering badly, but now the situation seems to be reversed in that the previously affected countries are seeing a decline while those initially low case number countries are seeing a spike.
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Probability can be deceptive. The concept sounds easy to understand and we glibly use the ideas in everyday life but there are many subtleties involved. Given how important probabilistic ideas are in life, some have suggested that it be introduced into school mathematics curricula much earlier than it currently is and discussed in more depth.

One subtlety can be highlighted by this example. Suppose that you read about a new study that finds that by taking some measures, you can reduce the risk of stroke by 50%. Should you adopt those measures?

To make a decision you need to weigh the benefit against the costs, which in this case may be that the measures involve taking medications that have rather serious side effects, or that the regimen involved is arduous, or that it is very expensive. But even taking those into account is not enough to decide because you need to know another key piece of information and that is the absolute risk numbers.

The relative risk is what is usually reported and quoted in the media. It is obtained by comparing the results of the test group with the control group. So if the test group has five positive cases and the control group has ten, then the relative risk reduction is 50%. But this ignores the importance of sample size that determines the absolute risk. If the sample size had been 10,000, the absolute risk would have dropped from 0.1% to 0.05%.

Paula Byrne, one of the authors of a recent study on the benefits of taking statins to lower cholesterol, says that focusing only on relative risk does not give enough information to make an informed decision.
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Commenter anat linked to a very nice visual display of the latest sunrise times across the US if Daylight Savings Times becomes the fixed time all year long, as the legislation passed the US Senate decrees. The House of Representative has not agreed as yet.

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As long time readers know, I grumble about that biannual ritual in the US of changing the clocks forward by one hour in the spring (when it becomes Daylight Savings Time) and then one hour back in the fall (when it reverts to Standard Time). We just made the change this past Sunday and I went around changing the eight clocks that are not connected to the internet. You would think that I would have been on top of this issue but I was taken completely by surprise to learn that the US Senate yesterday unanimously passed a resolution making DST permanent

That does not mean that the deed is done. The House of Representatives has not passed the measure and Joe Biden has not stated that he will sign the bill into law.
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I am a materialist in the sense that I think that all phenomena arise due to material entities interacting according to laws of nature. I have seen no reason to think that anything supernatural or mystical is needed to be invoked to explain anything. I have sometimes been asked by people, usually the religious seeking to challenge my atheistic viewpoint that the material world is all there is and does not allow for any gods, as to how I can explain love. They seem to think that love is an immaterial quantity and that believing in its existence requires the same leap of faith as believing in a god. I reply that love is an emotion that is created by the workings of my brain that releases certain substances that cause me to have that feeling I point out that when I die, any love that I feel for anyone or anything will die with me. It does not survive the death of my brain.
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