The pleasures of reading Feynman on Physics – V

Feynman finally gets around to discussing tensors 376 pages into volume II in “The Feynman Lectures on Physics” and a magnificent help it is (to me at least).  Tensors must be understood to have a prayer of following the math of General Relativity (a 10 year goal, since meeting classmate Jim Hartle who wrote a book “Gravity” on the subject).

There are so many ways to describe what a tensor is (particularly by mathematicians and physicists) that it isn’t obvious that they are talking about the same thing.   I’ve written many posts about tensors, as the best way to learn something it to try to explain it to someone else (a set of links to the posts will be found at the end).

So why is Feynman so helpful to me?  After plowing through 370 pages of Callahan’s excellent book we get to something called the ‘energy-momentum tensor’, aka the stress-energy tensor.  This floored me as it appeared to have little to do with gravity, talking about flows of energy and momentum. However it is only 5 pages away from the relativistic field equations so it must be understood.

Back in the day, I started reading books about tensors such as the tensor of inertia, the stress tensor etc.  These were usually presented as if you knew why they were developed, and just given in a mathematical form which left my intuition about them empty.

Tensors were developed years before Einstein came up with special relativity (1905) or general relativity (1915).

This is where Feynman is so good.  He starts with the problem of electrical polarizability (which is familiar if you’ve plowed this far through volume II) and shows exactly why a tensor is needed to describe it, e.g. he derives  the tensor from known facts about electromagnetism.  Then on to the tensor of inertia (another derivation).  This allows you to see where all that notation comes from. That’s all very nice, but you are dealing with just matrices.  Then on to tensors over 4 vector spaces (a rank 4 tensor) not the same thing as a 4 tensor which is over a 4 dimensional vector space.

Then finally we get to the 4 tensor (a tensor over a 4 dimensional vector space) of electromagnetic momentum.  Here are the 16 components of Callahan’s energy momentum tensor, clearly explained.  The circle is finally closed.

He briefly goes into the way tensors transform under a change of coordinates, which for many authors is the most important thing about them.   So his discussion doesn’t contain the usual blizzard of superscripts and subscript.  Covariant and contravariant are blessedly absent. Here the best explanation of how they transform is in Jeevanjee “An introduction to Tensors and Group Theory for Physicists”  chapter 3 pp. 51 – 74.

Here are a few of the posts I’ve written about tensors trying to explain them to myself (and hopefully you)

https://luysii.wordpress.com/2020/02/03/the-reimann-curvature-tensor/

https://luysii.wordpress.com/2017/01/04/tensors-yet-again/

https://luysii.wordpress.com/2015/06/15/the-many-ways-the-many-tensor-notations-can-confuse-you/

https://luysii.wordpress.com/2014/12/28/how-formal-tensor-mathematics-and-the-postulates-of-quantum-mechanics-give-rise-to-entanglement/

https://luysii.wordpress.com/2014/12/08/tensors/

If I were a billionaire

If I were a billionaire I’d fund the following research study immediately.  Where ?  Not Research Triangle Park, the Acela corridor or the Bay Area but Sturgis South Dakota.  Why?

Spend 11 minutes of your time looking at the following video — https://www.youtube.com/watch?v=aNIEOCFGr3s&feature=emb_rel_end%3Chttps://nam02.safelinks.protection.outlook.com/?

The 80th Annual Sturgis Motorcycle Rally began there 9 August. It is expected to attract between 250,000 and 500,000 people and last 10 days.  Masks are not required and the video shows that very few are wearing them.  Note the rather close seating for eating and drinking, the stores and restaurants with low ceilings and long horizontal extent (and rather poor ventilation)  I’m sure the actual event will have far closer human contact than shown as the video was shot when the festival was about to begin.

You’d never get an experiment like this to pass an institutional review board, but there it is for the taking  Mr. Billionaire.

Spend some of that cash getting vans to Sturgis and offer free COVID-19 testing (both antibody testing and genome testing) to any one wanting it.  This is an independent bunch, so all you ask is that they stay in touch and let you know how they’re doing in the weeks and months ahead.   Tell them, they’ll hear the results after the 19th when the festival ends if they want, so they’ll need a way for you to contact them.

Probably most will not divulge information about themselves, but you will  surely find some cooperative people.  So ask them to tell you about age, sex, medical conditions.  Offer to do a BMI for them.  Have your staff eyeball their ethnicity, rather than ask.  Since you are funding the study, you’l be able to keep the information completely private.

The study will tell us a huge amount about transmission, susceptibility, clinical course etc. etc.  You don’t need another house or mistress.  Take that cash and do something for humanity.

Of course, the population isn’t representative.  Almost entirely white, very few people over 70 or under 15 (please spend 11 minutes of your time looking at the video.  The level of obesity and smoking  is impressive).

Of course there will be ethical concerns.  Suppose you find someone shedding the virus — do you contact them?  Probably best to wait a few a weeks before testing.   This is a naturalistic study after all and you’re a billionaire not a doc.

Hurry there are just 7 more days to go.

 

 

Book Review: Tales of Impossibility

Here is a book for anyone who has had high school geometry and likes math.  It is “Tales of Impossibility” by David Richeson.  It’s full of diagrams and is extremely well written.  A bright high school student could go all the way to the end, and would learn a lot of abstract algebra, up to and including complex numbers, irrational numbers and transcendental numbers.  It describes the 2000+ year search for ways to trisect an angle, double the cube, construct any polygon using a compass and straight edge,  and find the area of a circle (squaring the circle), or prove that it was impossible using basic methods.

It took until the late 1800s to finish the job.  Proving that something is impossible is subtle and difficult.    The book is 368 pages long and contains 40 pages of notes and references, but it is definitely not turgid.

There is a huge amount of historical detail about each of the great figures who worked on the problems starting with Euclid and going on through the the Greek geometers, Fermat, Descartes.

The battles about what could be considered kosher in math occurred every step of the way and is well covered.  Could algebra be used to solve a geometric problem?  Was a negative number a number. What about an imaginary number, or an irrational one?   Was something you could draw using a marked ruler (neusis) really a geometric figure?

If you look at nothing else, have a look at how Descartes was able to multiply and divide the length of various lines, using nothing more that Euclid’s geometry (but apparently no one had figured it out before).

The ultimate impossibility proofs involved abstract algebra, so we meet Viete and Descartes, Galois, Hermite etc. etc.  So it might help if some high school algebra was on board.

For the right smart high school kid, this book is perfect.  For the cognoscenti or even for nonCognoscenti with a lifelong interest in math (such as me) there is a lot to learn.  The proofs of all the geometric statements are all well laid out, and now it’s time for me to go through the book a second time and follow closely.

Thank your inner retrovirus for your existence

When the human genome project was first rolled out 20 years ago it came as a shock to find out that 8% of our 3,200,000 nucleotide genome was made of retrovirus relics.  They are the perfect example of selfish DNA — they don’t do anything other than insure their transmission to the next generation.   They are the perfect parasite infecting the host without killing it.  Since they don’t have to do anything, mutations rapidly accumulate in them and none of them can make a functioning virus.

As most know, retroviruses have genomes made of RNA, which is reverse transcribed into by an enzyme they contain into a DNA copy (cDNA) which then is inserted into the genome of the host.  HIV1, the virus of AIDs is one such retrovirus.   Fortunately HIV1 hasn’t entered the genome of eggs or sperm, so it hasn’t become an endogenous retrovirus, but it is all over the DNA or immune cells of those infected.

What is even more interesting (and totally unexpected) is that the host can repurpose these retroviral relics to do something useful.

In fact they’ve become so useful that we couldn’t reproduce without them.  The syncytiotrophoblast layer of the placenta is at the maternal fetal interface.  It is a continuous structure, one cell deep formed by fusion of the constituent trophoblast cells.  The layer has microvillar surfaces which facilitate exchanges of nutrients and waste products between mother and fetus.

Syncytin1 is a protein expressed here.  It is produced from the env gene, of a Human Endogenous RetroVirus (HERV) called HERV-W.  Adding the protein to culture systems leads to syncytium formation.  Mice in which the gene has been knocked out die in utero, due to failure of trophoblast cells to fuse.

Well that’s pretty spectacular and not much commented on although it’s been known for 20 years.

It shows that the envelope protein from another retrovirus (HERV-K subtype HML-2 is expressed at high levels on human pluripotent stem cells.  Not only that it keeps them from differentiating — something important for our longevity — so we always have a few pluripotent stem cells around.

As a neurologist I find it fascinating that knocking down the env protein causes the stem cells to differentiate into neurons.  Don’t get too excited that we’ve found the fount of neuronal youth, as forced expression of the env protein in terminally differentiated neurons kills them.

Why do some socially isolate and some don’t

The current flare in US cases (and deaths) are likely due to a failure in social isolation, rather than a loosening of restrictions on activity.  Georgia loosened its restrictions back in April.  Following this, new cases dropped for two months, and deaths dropped for nearly 3 months, before rising again to pre-lockdown levels and above.  The number of new ‘cases’ can partially be attributed to more testing, but the number of deaths can not.  For links and the exact numbers see the copy of the previous post after the ***

I think the rise is partially explainable by a failure of social distancing. Have a look at this  https://nypost.com/2020/07/18/video-shows-people-in-queens-flooding-streets-without-masks/.   It may not be a COVID party in name, but it is in fact.

That being the case, wouldn’t it be nice to know why some people social distance and others do not.

Incredibly, a paper just came out looking at exactly that Proc. Natl. Acad. Sci. vol. 117 pp. 17667 – 17674 ’20 (28 July).  It’s likely behind a paywall so let me explain what they did.

The work was conducted in the first two weeks after the 13 March declaration of a national emergency.  Some 850 participants from the USA had their working memory tested using the Mechanical Turk from Amazon — https://en.wikipedia.org/wiki/Amazon_Mechanical_Turk.  Essentially they are volunteers.  I leave it to you to decide how characteristic of the general population at large these people are.   My guess is that they aren’t.

Then the 850 were subsequently asked how much they had complied with social distancing.

But first, a brief discussion of working memory — more is available at https://en.wikipedia.org/wiki/Working_memory

Working memory is tested in a variety of methods, but it basically measures how many objects you can temporarily hold in your head at one time.  One way to test it, is to give you a series of digits, and then ask you to repeat them backwards (after a lag of a second or so).  Here’s what the authors used —

“Participants performed an online visual working memory task, in which they tried to memorize a set of briefly presented color squares for  half a second and after a 1 second delay tried to identify a changed color in the test display by clicking on it using a computer mouse.”

The more you can hold in your head for a short period of time, the more working memory you have.  There is a lot of contention about just what intelligence is and how to measure it, but study after study shows that the greater your working memory, the more intelligent you are.

To cut to the chase — here are their results.

The greater their working memory, the greater the degree of compliance with social distancing.

Here is the author’s explanation –what’s yours?

“We find that working memory capacity contributes unique variance to individual differences in social distancing compliance, which may be partially attributed to the relationship between working memory capacity and one’s ability to evaluate the true merits of the recommended social distancing guidelines. This association remains robust after taking into account individual differences in age, gender, education, socioeconomic status, personality, mood-related conditions, and fluid intelligence.”

Talk about currency and relevance ! !   If failure of social distancing explains the rise in cases, studies like this will help us attack it.

Here is the older post with numbers and links

***

The News is Bad from Georgia

This is an update on a series of post about Georgia and the effect of relaxing restrictions on activity.  If you’ve been following the story, this post is somewhat repetitive, but I’d rather not leave newcomers behind. As of 14 July Georgia seemed to be bucking the trend of increasing deaths (but not of increasing ‘cases’ however defined).  No longer.

 https://dph.georgia.gov/covid-19-daily-status-report.  Page down past the map to the chart with 3 tabs —  cases (which means daily newly diagnosed cases), cumulative cases, and death.  Clicking on the tabs will move you back and forth (or better if your screen is big enough open the link twice and compared cases vs. deaths.

Georgia has changed the way it reports cases, no longer waiting 14 days before result are secure.  I also think they changed some of the older numbers.  I don’t recall seeing over 70 deaths in a day in May and June, yet the current chart shows 4 of them.  There is no way to get the old reports from the Georgia department of health, by clicking on the links in the old posts on the subject.  They all take you to the current one.

The 7 day average of deaths back in 25 April was 35, new cases  740 based on detection of viral genome or antibodies to it — not sick people

Sadly now the 7 day average of death is now 45 and new cases 3700.

The charts allow you to see when both new cases and deaths began to rise.  The number of new cases began to spike 16 June and the number of death began to increase 19 July (eyeball the charts, and you’ll see that these are not precise numbers.  So there was about a 1 month lag between the increases.

So were the doom and gloom sayers correct?  Here they are again to refresh your memory.

From The Atlantic — “Georgia’s Experiment in Human Sacrifice — The state is about to find out how many people need to lose their lives to shore up the economy.” — https://www.theatlantic.com/health/archive/2020/04/why-georgia-reopening-coronavirus-pandemic/610882/

Possibly they were right, but deaths actually decreased for a month or two after 25 April hitting a low of 13 daily deaths on 2 July.   I don’t think any of them predicted a lag of 2 months before the apocalypse.

Most likely it was a change in behavior.  Have a look at this  https://nypost.com/2020/07/18/video-shows-people-in-queens-flooding-streets-without-masks/.   It may not be a COVID party in name, but it is in fact.

At first glance it appears that they are trying for a Darwin award, but on second glance, based purely on a cost benefit analysis (to them only) the chances of a healthy 18 – 20 year old dying from COVID19 are less than 1 in a thousand.  Libido is incredibly intense at that age.   I’m not sure what I would have done in their shoes.  Here are some statistics from Florida with numbers large enough to be significant

Here is some older data from Florida  (from their department of health) — http://ww11.doh.state.fl.us/comm/_partners/covid19_report_archive/state_reports_latest.pdf

Age  Range     Number of Cases  Number of Hospitalizations Deaths

14 – 24              54,815                                503                                    12

25 – 34             70,030                              1,315                                    34

This is a risk of death if you are a ‘case’ however defined of less than 1/2,000.

This is age range of most of folks in the video. Further more recent examples are lifeguards in NY and on Cape Cod.

Think of all the gay men who knew full well how AIDS was transmitted, still got it and died.  Libido is powerful.  The classic example is Randy Shilts who wrote the magnificent “And the Band Played On” in 1987 about the early days of the epidemic.  He knew everything there was to know about the way the AIDS virus (HIV1) was transmitted yet he himself died of AIDS.

Further examples are lifeguards in NY and on Cape Cod.

 

The News is Bad from Georgia

This is an update on a series of post about Georgia and the effect of relaxing restrictions on activity.  If you’ve been following the story, this post is somewhat repetitive, but I’d rather not leave newcomers behind. As of 14 July Georgia seemed to be bucking the trend of increasing deaths (but not of increasing ‘cases’ however defined).  No longer.

 https://dph.georgia.gov/covid-19-daily-status-report.  Page down past the map to the chart with 3 tabs —  cases (which means daily newly diagnosed cases), cumulative cases, and death.  Clicking on the tabs will move you back and forth (or better if your screen is big enough open the link twice and compared cases vs. deaths.

Georgia has changed the way it reports cases, no longer waiting 14 days before result are secure.  I also think they changed some of the older numbers.  I don’t recall seeing over 70 deaths in a day in May and June, yet the current chart shows 4 of them.  There is no way to get the old reports from the Georgia department of health, by clicking on the links in the old posts on the subject.  They all take you to the current one.

The 7 day average of deaths back in 25 April was 35, new cases  740 based on detection of viral genome or antibodies to it — not sick people

Sadly now the 7 day average of death is now 45 and new cases 3700.

The charts allow you to see when both new cases and deaths began to rise.  The number of new cases began to spike 16 June and the number of death began to increase 19 July (eyeball the charts, and you’ll see that these are not precise numbers.  So there was about a 1 month lag between the increases.

So were the doom and gloom sayers correct?  Here they are again to refresh your memory.

From The Atlantic — “Georgia’s Experiment in Human Sacrifice — The state is about to find out how many people need to lose their lives to shore up the economy.” — https://www.theatlantic.com/health/archive/2020/04/why-georgia-reopening-coronavirus-pandemic/610882/

Possibly they were right, but deaths actually decreased for a month or two after 25 April hitting a low of 13 daily deaths on 2 July.   I don’t think any of them predicted a lag of 2 months before the apocalypse.

Most likely it was a change in behavior.  Have a look at this  https://nypost.com/2020/07/18/video-shows-people-in-queens-flooding-streets-without-masks/.   It may not be a COVID party in name, but it is in fact.

At first glance it appears that they are trying for a Darwin award, but on second glance, based purely on a cost benefit analysis (to them only) the chances of a healthy 18 – 20 year old dying from COVID19 are less than 1 in a thousand.  Libido is incredibly intense at that age.   I’m not sure what I would have done in their shoes.  Here are some statistics from Florida with numbers large enough to be significant

Here is some older data from Florida  (from their department of health) — http://ww11.doh.state.fl.us/comm/_partners/covid19_report_archive/state_reports_latest.pdf

Age  Range     Number of Cases  Number of Hospitalizations Deaths

14 – 24              54,815                                503                                    12

25 – 34             70,030                              1,315                                    34

This is a risk of death if you are a ‘case’ however defined of less than 1/2,000.

This is age range of most of folks in the video. Further more recent examples are lifeguards in NY and on Cape Cod.

Think of all the gay men who knew full well how AIDS was transmitted, still got it and died.  Libido is powerful.  The classic example is Randy Shilts who wrote the magnificent “And the Band Played On” in 1987 about the early days of the epidemic.  He knew everything there was to know about the way the AIDS virus (HIV1) was transmitted yet he himself died of AIDS.

Further examples are lifeguards in NY and on Cape Cod.

The Dr. Jekyll and Mr. Hyde protein

If there ever was a protein with a Dr. Jekyll and Mr. Hyde character (https://en.wikipedia.org/wiki/Dr._Jekyll_and_Mr._Hyde_(character))it is EZH2, a protein whose function we thought we knew.

EZH2 is an enzyme which puts methyl groups on lysine #27 of histone H3 (forming H3K27Me3).     So as good chemists that tells you that it removes the positive charge usually found on the amine group lysine at physiological pH.  But chemistry is helpless here unless you know what histone H3 does.  Addendum 27 July — clearly I’m not a good chemist when I write late at night.  Ashutosh points out that the positive charge on nitrogen at physiologic pH remains even when one, two or all the hydrogens are replaced by methyl groups.  Acetylation of the amino group of lysine removes the positive charge.  The methylation of lysine #27 is just one part of the histone code allowing other proteins to specifically bind here. As of 2013 some 130 different post-translational histone modifications were known.  

The DNA in each of our cells is just over a yard long.  To fit inside it must be compacted down.  4 different histone proteins get together to form an octomer around which DNA wraps in nearly two complete turns, compacting DNA down by a factor of ten.  The details of the further compaction have been studied for 50 years and are still under debate.

You’d think that the methylation of lysine #27 and loss of the positive charge would make it less likely to bind to the negative phosphates of the DNA chain.  This should free up the DNA so it can be transcribed to RNA and make proteins.

That’s not at all what happens. There are other proteins which bind H3K27Me3 and compact the DNA down so it becomes inactive (unable to be transcribed into mRNA).

Well that was the state of play until Proc. Natl. Acad. Sci. vol. 117 pp. 16992 – 17002 ’20.  So much for Dr. Jekyll.

Some forms of cancer activate kinase enzymes (AKT, JAK3) which place phosphates on serine #21 or tyrosine #244 of EZH2 respectively.   This causes a giant structural arrangement of amino acids #135  to #195.  Now the protein interacts with another enzyme p300 (a histone acetyl transferase) whose net effect is to UNcompact DNA and activate gene transcription.  Even worse, the transcription products of the genes help the cancer along.  Definitely Mr. Hyde.

This is a radically different function for EZH2 and you have to wonder how many other proteins lead double lives like EZH2.

The classic examples of a huge structural shift in a protein complex are the spike proteins of viruses (notably SARS-CoV-2), which unfold to form a needle piercing a cell allowing injection of the viral genetic material. Here are some nice pictures of the fusion protein of influenza virus in action — http://faculty.washington.edu/kklee/Influenza_SAXS.html.  But this is structural change in pursuit of a known physiological effect.

The double life of EZH2 is remarkable.   Some proteins have more than one effect in the cell — this is called moonlighting.  One example is cytochrome c, which is normally found in the intermembrane space of the mitochondrion where it is involved in electron transport.  When it is released into the cell cytoplasm due to mitochondrial damage, the cell quietly kills itself (apoptosis) — definitely a moonlighting function.  But the structure of cytochrome c doesn’t change to accomplish this, just its location.

Fascinating stuff, and the paper should be read to see just how profound the shift in structure that EZH2 undergoes actually is.

This is just a small window into the intricacy (and beauty if you will) of the cellular and biochemical events underlying our existence.  There is far more to discover, so stay tuned.

For some further musings on this point — https://luysii.wordpress.com/2009/09/17/the-solace-of-molecular-biology/

Kon-Tiki lives !

Could anything be more fascinating to a prepubertal male than setting off to explore the Pacific in a raft?  It’s Tom Sawyer and Huck Finn writ large.  Then there was the protagonist, Thor Heyerdahl a red bearded Norseman from central casting.  I read the book (Kon-Tiki: Across the Pacific in a Raft) when mother got it as a Book of The Month selection in the 50s.

Ostensibly this was to explore the possibility that the Polynesians far across the pacific had come from the people living on the west coast of South America.  Actually it was to have a great adventure.  The raft made it across the Pacific, after a voyage of 7,000 kiloMeters (4,350 miles) and 101 days.   Just to show how incredible the journey was,  Easter Island is said to be ‘relatively close’ to S. America (3,723 miles) — which is like saying LA is relatively close to NYC in North America.

Despite their success the cognoscenti deprecated the trip.  Even though a South American plant (the sweet potato) has been found on Easter Island, it was held that the Polynesians went to South America and brought it back.

Well Heyerdahl was right but it took nearly 70 years to prove it.  A study in Nature (vol. 583 pp. 524 – 525, 572 – 577 ’20) looked at the DNA of people from Rapa Nui (Easter Island) and 17 populations from various Pacific Islands, and 15 populations from the Pacific coast of South America.  Some 807 individuals were tested.   The analysis was tricky as there is European admixture in both places and getting rid of this wasn’t easy.  The Polynesians definitely showed traces of South American genetic material.

 

New Delhi has 4.4 million COVID19 cases — Run !!

New Delhi has 4.4 million COVID19 cases ! ! !  Well that’s how the US press would have handled it, generating all sorts of clicks on their websites.  Fortunately the Indians are far more intelligent, noting that they have had a total 123,747 cases of clinical illness due to the pandemic virus, using the term COVID19 case as the term was originally defined — someone clinically ill with the virus.  That’s how the term was initially used in the USA, until they began calling a positive antibody test or finding the viral genome, COVID19.

How did they get the 4.4 million figure?  Well it’s based on tests for antibodies to the virus conducted from 27 June to 10 July, with a total of 21,387 samples from 11 districts of New Delhi by the National Center for Disease Control in collaboration with the Delhi government.  Here’s a link to a very circumspect article about the study — https://www.firstpost.com/health/over-23-delhi-residents-have-covid-19-antibodies-shows-sero-survey-data-ncdc-says-77-still-susceptible-8624511.html.

I’m hardly a regular reader of the Indian press, so I have no idea of the site’s reputation or orientation.  However they do quote National Centre for Disease Control Director Dr Sujeet Kumar Singh at some length.

At any rate the 4.4 million figure comes from multiplying the overall positivity rate from the samples (23.5%) by the population of New Delhi which is around 20,000,000 !

Also noted in the article is the number of clinically ill people with COVID19. The number of currently active cases of COVID19 stood at 15,288, and the overall total since the beginning of the epidemic is 123,747.

Clearly, if the study is to be believed, infection with the pandemic virus is usually benign and asymptomatic.

Addendum 23 July — People have been tested for antibodies to the pandemic virus just about everywhere now.  Amazingly, my home state of Massachusetts had tested some 60,000 souls for it by 18 June, but they won’t say how many had the antibodies ! ! That’s insane.  Would it destroy a narrative? https://www.bostonglobe.com/2020/06/18/nation/state-has-tested-60000-people-covid-antibodies-wont-say-how-many-tested-positive/

COVID19 will be with us for a long time

Feast your eyes on this video of hundreds of maskless  people partying in the streets of Queens NYC 18 July.  It has to be seen to be believed.  Unfortunately, you’ll have to sit through some ads, but it’s worth the wait.

https://nypost.com/2020/07/18/video-shows-people-in-queens-flooding-streets-without-masks/.   Reports of COVID19 parties have been critized as being urban legends, with no specifics as to time or place or people being given.  Here’s Queens NYC one night — It may not be a COVID19 party in name, but it is in fact.

Much has been made of the spread of the pandemic in the South, notably Florida and Texas.  It has been laid to premature lifting of restrictions with Trump leading the charge.

Well New York City hasn’t, and the people shown partying are unlikely to take the President’s words as holy writ.   Two questions arise

l. Are these people insane or rational?

2. Is what they are doing likely to cause a similar surge in cases?

It’s time to deal with the world as it is, rather than the world as we’d like to be (enter the world of docs confronting any new disease — think Everett Koop and the early days of AIDS).

Forgetting the second question for a time, viewed from their perspective, their behavior is rational — which is not to say I condone it.

Here is data from Florida through yesterday (from their department of health) — http://ww11.doh.state.fl.us/comm/_partners/covid19_report_archive/state_reports_latest.pdf

Age  Range     Number of Cases  Number of Hospitalizations Deaths

14 – 24              54,815                                503                                    12

25 – 34             70,030                              1,315                                    34

This is age range of most of folks in the video

So the risk of death for 14 – 24 is .02% or under 1/1,000 — ditto for the 25 – 34 age group.   And that’s if the revelers actually acquire the virus.  So from a selfish perspective, their behavior is rational.

Is their behavior harmful to society at large?  You’d think so.

Well maybe not.  Here’s some work from 3 months ago.

https://www.nytimes.com/2020/07/09/nyregion/nyc-coronavirus-antibodies.html–https://www.cnbc.com/2020/04/23/new-york-antibody-study-estimates-13point9percent-of-residents-have-had-the-coronavirus-cuomo-says.html.

The State randomly tested 3,000 people at grocery stores and shopping locations across 19 counties in 40 localities to see if they had the antibodies to fight the coronavirus, indicating they have had the virus and recovered from it. With more than 19.4 million people residents, according to U.S. Census data, the preliminary results imply that at least 2.7 million New Yorkers have been infected with Covid-19.

With more than 19.4 million residents, according to U.S. Census data, the preliminary results indicate that at least 2.7 million New Yorkers have been infected with Covid-19.  They weren’t all hospitalized.

Here’s some work this month from Queens — https://www.nytimes.com/2020/07/09/nyregion/nyc-coronavirus-antibodies.html

At a clinic in Corona, a working-class neighborhood in Queens, more than 68 percent of people tested positive for antibodies to the new coronavirus. At another clinic in Jackson Heights, Queens, that number was 56 percent. But at a clinic in Cobble Hill, a mostly white and wealthy neighborhood in Brooklyn, only 13 percent of people tested positive for antibodies.

So the disease has already to spread to half the population in some neighborhoods in Queens. If even 10% of them were sick that would have been 140,000 hospitalizations.  It didn’t happen.

So some parts of Queens may be close to herd immunity.