Today is the last day of the year. We use a number system, calling it 2021. It is based on a solar year and dates back some time, with adjustments over the centuries as needed because the day/night cycle and the orbit don't really come out in even numbers. Generally the adjustments are small, though every four years a day is added because the orbit is not 365 days, but closer to 365.25. It's not exactly that, either, so other adjustments are built in, but rare enough that most people won't experience them. Smaller adjustments are made in public time as the actual time of our planetary rotation is not 24 hours, but off a little. The exact moment for some phenomena can be observed and recorded, but how many seconds are really in a day? A day is very slightly longer than 24 hours, which adds up to a second every year and a half or so, and over the longer term, the rotation has slowed by a bit over a millisecond per century. These variations are known by science and adjustments are made. People know about Leap Year, the years with an extra day. Leap seconds are added to the clock at the end of June or December as needed, but without much notice or fuss by the general public.
Most of us don't need to follow all this detail. Adjustments of a second in public time has no effect on when you sit down for lunch or join your next Zoom meeting, though if those adjustments weren't made, eventually the shifts in time would become large enough to be noticeable. Systems are in place to take care of them so business and life can go on uninterrupted and with confidence that the trains will not crash due to time differences across jurisdictions.
This is one clear illustration of the details of existence that we don't bother with most of the time. Such details are everywhere. Sometimes they are much more important, and unexpected variations can have very serious consequences. Like GM's exploding batteries. The science seemed to work. The engineering probably required some adjustment because electronics doesn't always work quantitatively according to the design specs for each piece. And most of the batteries seem to function well enough. But some overheat and explode. That is something that will probably get fixed, eventually. Maybe not. Maybe the Chevy Bolt will cease to exist and serve as a cautionary tale for the whole electric vehicle industry. We want consistency and accuracy, but we don't consider how truly complex our world is, instead using the simplified version that allows us to get on with life without asking too many detailed questions. Reality is beyond our comprehension.
Most people don't understand viruses. All the changing recommendations from public health officials during this pandemic have caused confusion and distrust in the public, including among health care professionals, who know some about health care but not enough, apparently, to follow the changes of science in real time. Living with constant uncertainty is a part of the human condition, but being reminded of that so much lately is wearing. The basic recommendations have not changed much. We know the general rules of how respiratory viruses spread and what actions help to decrease the risk of infection. But we want exact numbers for those risks. We want to know how many days or hours a person who tests positive is still capable of spreading the virus. But there is no exact number of days or hours. It will vary across the population according to too many variables to list, most of which have never been studied because they involve interaction of the complexities of human physiology at levels we don't understand, or so I expect. I'm not familiar with the data on which the decrease in isolation time recommended by the CDC is based. First exposure meant a 14 day isolation. Then 10 day. Now 5 day. Only applicable if the patient has no symptoms. Does the patient recognize all relevant symptoms? I wouldn't bet my life on it. And I want to protect my life.
In my case, I'm not very social by nature so social distancing and staying home are not burdens. I may live under pandemic rules by choice from now on. The heavier burden is watching so many people fight against useful recommendations out of fear and ignorance, and know there is nothing I can do to make that change. Another one of those details that science has revealed: people who oppose vaccination will not change their minds based on data and truth. That is an uncomfortable details about the human condition.