There has emerged a rough rule of thumb for face masks that says that when it comes to reducing the chances of transmission of the covid-19 virus, N95 masks are the best, with paper surgical masks next, and cloth masks the least effective, compared to wearing no mask at all Now the CDC has come out with a study that provides a more quantitative comparison.
There is a very strong desire among some segments of the population to make contact with dead people. This desire has been exploited by charlatans, people who claim that (for a fee, of course) they can channel your loved ones. The methods used have varied over time. In the US, the rise in interest in communicating with the dead coincided with the Civil War that saw massive numbers of dead people that left their families devastated and seeking some form of comfort.
In the mid-19th century, in the early days of photography, the husband and wife team of William and Hannah Mumler created a sensation by taking photographs of people that showed the ghosts of their dead loved ones hovering around them, such as this one of the ghost of Abraham Lincoln standing behind his wife Mary Todd Lincoln.
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One of the things that surprised me after coming to the US is how many students (and even adults) believed that it was Christopher Columbus who established the fact that the Earth was round and that prior to his 1492 voyage across the Atlantic, people believed the Earth was flat. (Some people still believe the Earth is flat but that is another story.)
I wrote an article about this myth that appeared in Phi Delta KAPPAN, vol. 88, no. 8, p. 590-592, April 2007 that you can read by following the link below.
The pandemic with its virus mutations has rekindled my interest in the mathematics of evolution. Way back in 2007, I wrote a 20-part series of blog posts on evolution. This was way ‘out of my lane’, as the kids say these days, since I am a physicist and have zero formal training in biology, having taken my one and only course in that subject when I was in eighth grade. But I did this for the same reason I write about a lot of things, in order to force myself to learn about a topic that interests me and to sort out my ideas.
One of the things that had intrigued me is how a mutation that occurs in just one organism could become not just dominant in the population but end up being the only one. In some posts in the series, I discussed the mathematics of how this happens, which I have edited and reproduce here.
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I am an omnivore with a guilty conscience. What I mean by that is that I think that vegetarians and vegans have convincing arguments based on moral, ethical, economic, and climate reasoning that that is the way to live. But I have simply not had the will power to take the leap and switch over to that diet. Instead, I have taken the minimal step of reducing my meat consumption.
I am aware that some arguments have been advanced to justify meat eating based largely on the fact that it is an easy way to get proteins and a few essential vitamins and on a more specious argument that since our evolutionary history reveals that we were meat eaters from a long time back, that means that eating meat must provide some evolutionary benefit.
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When it comes to wearing masks during the pandemic, not all masks are equal in the protection they provide. From what I have read, cloth masks seem to provide the least protection, though they allow the wearer colorful options and the ability to make some kind of statement, though why some people feel the need to make statements through their attire is something that I find puzzling. The blue surgical masks appear to be better than cloth and the N95 masks are the best. But while the surgical masks are relatively cheap, the N95 masks are pricey (ranging from $1 to $3 each) and that raises the question of how long one can use them and whether they can be reused.
The good news is that the answer is yes, based on the fact that the coronavirus has a survival time of about 72 hours when outside a host.
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The space telescope has reached its destination of the second Lagrange point.
The mirrors on the space observatory must still be meticulously aligned and the infrared detectors sufficiently chilled before science observations can begin in June. But flight controllers in Baltimore were euphoric after chalking up another success.
“We’re one step closer to uncovering the mysteries of the universe. And I can’t wait to see Webb’s first new views of the universe this summer!” the Nasa administrator, Bill Nelson, said in a statement.
“Wow, what a ride this last month it’s been,” said Amber Straughn, a deputy project scientist for Nasa.
The telescope has been described as a “time machine” by scientists and will enable astronomers to peer back further in time than ever before, all the way back to when the first stars and galaxies were forming 13.7bn years ago. That’s a mere 100m years from the Big Bang, when the universe was created.
The Webb will also hunt for signs of extraterrestrial life.
Considered the successor to the Hubble, which orbits 330 miles (530km) up, the Webb is too far away for emergency repairs. That makes the milestones over the past month – and the ones ahead – all the more critical.
…Whether chasing optical and ultraviolet light like the Hubble or infrared light like the Webb, telescopes can see farther and more clearly when operating above Earth’s distorting atmosphere. That’s why Nasa teamed up with the European and Canadian space agencies to get Webb and its massive mirror – the largest ever launched – out into the cosmos.
So far, things have gone really smoothly for this highly complicated mission but there are still challenges ahead. One can only hope that now that the major hurdles have been overcome, especially the whole business of unfolding of a tennis court size structure from the small confines of a rocket nose cone, that some small glitch does not ruin things.
The whole operation reflects great credit on all the engineers and scientists who were involved in designing, building, and launching it.
(Previous posts in this series: Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11, Part 12, Part 13, Part 14)
This series started by asking a simple question, whether a charged particle and a neutral particle would fall at the same rate when dropped from the same height and reach the ground at the same time. You would think that it would have a simple answer. But no. After a fairly long journey, we arrived at the conclusion that they would. But in the process, the series had to address a whole host of related issues along the way. While many of those were seemingly resolved, there are some fundamental questions that remain murky.
We saw in part #13 that the mass of a point charge like an electron is not a simple thing, because an electric charge has an associated electric field that itself has energy and thus should be thought of as contributing to the mass, except that the field energy density goes to infinity at zero distances, which is of course awkward for point-like charges. By looking at the radiation reaction force created by an accelerating charge, we learned about something called the acceleration energy Q that increases with the speed of a charge, and the energy radiated by a linearly accelerating charge comes from this source.
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I remain intrigued by the so-called ‘Havana Syndrome’, the strange affliction reported by some (mostly) US government and embassy officials when they are in other countries. Starting in 2016, these people reported hearing ringing or chirping sounds and headaches and the like. Since the first reports came from US embassy personnel in Havana, people jumped to the conclusion that the Cubans or Russians were trying out some new kind of weapon using targeted microwaves or ultrasound. But that theory always seemed implausible, both for technical and geopolitical reasons.
The US government has devoted considerable effort to try and identify the cause with little success. Now the CIA has issued yet another report that suggests that the ‘foreign power’ theory is not tenable.
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Unless you have some kind of medical condition that makes the risk of vaccination greater than the risk of getting covid-19, you should get vaccinated. But there are people who decide, against the best scientific advice, that they know better alternatives. Not all of them are rabid anti-vaxxers or are opposing it because of some ideological fixation or because they believe in some bizarre conspiracy theory that it is a device for the government to gain control over one’s body. There are those who do not get it because they have folkloric beliefs, such as that healthy people have natural immunity or that the symptoms will not be serious or that certain practices such as wellness or Ayurveda or other folk remedies will stave off the infection.
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