3 ms·

Apparently the CDC has yet to catch up to 19th century physics. The physics of small particles moving in the air ("Brownian motion") was completely figured out

by ddxxdd 5y ago

Apparently the CDC has yet to catch up to 19th century physics. The physics of small particles moving in the air ("Brownian motion") was completely figured out by Einstein back in 1905. Given a virus' size and weight, it should be trivial for a physics graduate student to simulate how long it will be airborne.

techdragon 5y ago
The thing about medicine is they like to test. Theory and simulation are nice but it’s just not medicine and therefore not suitable for a doctor to tell to someone as “medical advice” with all of the legal burden of malpractice that the term entails. “What if I’m wrong?” is a question that keeps good doctors awake at night and bad doctors have forgotten to ask themselves… when this kind of question weighs on you, it’s natural human behaviour to become more cautious, to become risk averse and question the validity of newly presented information due to the potential that regardless of if their current understanding is wrong, there’s no inherent guarantee that the new information is any less wrong. And so medicine is understandably a slow moving science, and the practice of medicine moves even slower as it represents the slow filtration of the cutting edge of medicine the science, through a complex web of human interaction. Which with a dash of “social capital” theory, makes it easy to see why we have unfortunately often ignored sound advice like this. The mistaken assumptions of people viewing a person who’s expertise bridges two disparate fields, as being unable to understand things as deeply, clearly or fully, as the people dedicated to just one of those fields.
- svantana 5y ago
  I can see your point, but isn't the WHO tweeting “FACT: #COVID19 is NOT airborne.” an example of the opposite? They made a hard assertion without any clear proof to back it up.
  - taxicabjesus 5y ago
    Hmm? interesting. Here's the offending tweet: FACT: #COVID19 is NOT airborne. The #coronavirus is mainly transmitted through droplets generated when an infected person coughs, sneezes or speaks. To protect yourself: -keep 1m distance from others -disinfect surfaces frequently -wash/rub your hands -avoid touching your Eyes Nose Mouth - https://twitter.com/who/status/1243972193169616898 https://twitter.com/who/status/1243972193169616898 The WHO gave a lot of bad advice. Some say that it was intentionally misleading. Promoting ventilation as a reasonable treatment for the initial stages of covid-19 was the worst possible advice to give front-line medical practitioners who didn't know what they were dealing with. We now know that the fecal-aerosol route of transmission is very important. Forbes has a recent piece about the fecal-oral/aerosol route: https://www.forbes.com/sites/williamhaseltine/2021/03/22/preventing-fecal-oral-and-fecal-aerosol-transmission-of-covid-19/ https://www.forbes.com/sites/williamhaseltine/2021/03/22/pre... Another tweet by ... someone was about how the masks effectively aerosolize droplets. Keeping bathrooms open but requiring face coverings was an exercise in futility. In the case of COVID-19, the WHO seems to have implemented #PrasadsLaw [0]. "Prasad’s Law: Medical goods and services that concentrate wealth can be paid for; medical goods and services that disperse wealth are “unaffordable.”" [0] https://news.ycombinator.com/item?id=21728864 https://news.ycombinator.com/item?id=21728864
    - rhodozelia 5y ago
      Farts are deadly now?
sandworm101 5y ago
>> Given a virus' size and weight, it should be trivial for a physics graduate student to simulate how long it will be airborne. How long it remains airborne is beside the point. Does that physics grad know how long/if the virus can survive once it dries up? Do they know how long it will survive exposure to light? Do then know whether the virus can cling to dust particles? Even brownian motion is only half the story. Does the physics grad understand airflow in office spaces? Do they understand how fast air moves when a person coughs? How much turbulence is caused by opening an office door? Plenty of things can stay airborne for extended periods because of aerodynamics without regard to brownian motion (snow/rain/dust/salt etc). That physics grad better come with minors in aerodynamics, kinesiology, microbiology ... even some basic meteorology would be helpful.
- Enginerrrd 5y ago
  As an civil / environmental engineer, I can assure you that particle size and average settling time is INCREDIBLY important to consider and will cover basically all of your supposed edge cases to the point of being statistically irrelevant. You would handle those edge cases by simply including a safety factor in the required residence time of the average particle within the system considered (or equivalently, you'd specify a certain log removal of pathogens). The end result of all your edge cases that you seem to think are so important is something like: "Ok, 1 in 100,000 may still get sick with this design. Good enough." You can make the same arguments for drinking water, and yet, as long as you follow the rules, it is unbelievably safe, despite the fact that no one gave a shit about turbulence along the baffles in the treatment tank.
Izkata 5y ago
Per that Wired article, it was intentionally ignored when the first virus-related research came up in the 1940s because it was too close to the discredited miasma theory. > Given a virus' size and weight, it should be trivial for a physics graduate student to simulate how long it will be airborne. This is also in the article, known research from decades ago. Social distancing is in fact based on a misunderstanding and conflation of a few things in that early research.

by ddxxdd 5y ago

techdragon 5y ago

The thing about medicine is they like to test. Theory and simulation are nice but it’s just not medicine and therefore not suitable for a doctor to tell to someone as “medical advice” with all of the legal burden of malpractice that the term entails. “What if I’m wrong?” is a question that keeps good doctors awake at night and bad doctors have forgotten to ask themselves… when this kind of question weighs on you, it’s natural human behaviour to become more cautious, to become risk averse and question the validity of newly presented information due to the potential that regardless of if their current understanding is wrong, there’s no inherent guarantee that the new information is any less wrong. And so medicine is understandably a slow moving science, and the practice of medicine moves even slower as it represents the slow filtration of the cutting edge of medicine the science, through a complex web of human interaction. Which with a dash of “social capital” theory, makes it easy to see why we have unfortunately often ignored sound advice like this. The mistaken assumptions of people viewing a person who’s expertise bridges two disparate fields, as being unable to understand things as deeply, clearly or fully, as the people dedicated to just one of those fields.

svantana 5y ago
I can see your point, but isn't the WHO tweeting “FACT: #COVID19 is NOT airborne.” an example of the opposite? They made a hard assertion without any clear proof to back it up.
- taxicabjesus 5y ago
  Hmm? interesting. Here's the offending tweet: FACT: #COVID19 is NOT airborne. The #coronavirus is mainly transmitted through droplets generated when an infected person coughs, sneezes or speaks. To protect yourself: -keep 1m distance from others -disinfect surfaces frequently -wash/rub your hands -avoid touching your Eyes Nose Mouth - https://twitter.com/who/status/1243972193169616898 https://twitter.com/who/status/1243972193169616898 The WHO gave a lot of bad advice. Some say that it was intentionally misleading. Promoting ventilation as a reasonable treatment for the initial stages of covid-19 was the worst possible advice to give front-line medical practitioners who didn't know what they were dealing with. We now know that the fecal-aerosol route of transmission is very important. Forbes has a recent piece about the fecal-oral/aerosol route: https://www.forbes.com/sites/williamhaseltine/2021/03/22/preventing-fecal-oral-and-fecal-aerosol-transmission-of-covid-19/ https://www.forbes.com/sites/williamhaseltine/2021/03/22/pre... Another tweet by ... someone was about how the masks effectively aerosolize droplets. Keeping bathrooms open but requiring face coverings was an exercise in futility. In the case of COVID-19, the WHO seems to have implemented #PrasadsLaw [0]. "Prasad’s Law: Medical goods and services that concentrate wealth can be paid for; medical goods and services that disperse wealth are “unaffordable.”" [0] https://news.ycombinator.com/item?id=21728864 https://news.ycombinator.com/item?id=21728864
  - rhodozelia 5y ago
    Farts are deadly now?

sandworm101 5y ago

>> Given a virus' size and weight, it should be trivial for a physics graduate student to simulate how long it will be airborne. How long it remains airborne is beside the point. Does that physics grad know how long/if the virus can survive once it dries up? Do they know how long it will survive exposure to light? Do then know whether the virus can cling to dust particles? Even brownian motion is only half the story. Does the physics grad understand airflow in office spaces? Do they understand how fast air moves when a person coughs? How much turbulence is caused by opening an office door? Plenty of things can stay airborne for extended periods because of aerodynamics without regard to brownian motion (snow/rain/dust/salt etc). That physics grad better come with minors in aerodynamics, kinesiology, microbiology ... even some basic meteorology would be helpful.

Enginerrrd 5y ago
As an civil / environmental engineer, I can assure you that particle size and average settling time is INCREDIBLY important to consider and will cover basically all of your supposed edge cases to the point of being statistically irrelevant. You would handle those edge cases by simply including a safety factor in the required residence time of the average particle within the system considered (or equivalently, you'd specify a certain log removal of pathogens). The end result of all your edge cases that you seem to think are so important is something like: "Ok, 1 in 100,000 may still get sick with this design. Good enough." You can make the same arguments for drinking water, and yet, as long as you follow the rules, it is unbelievably safe, despite the fact that no one gave a shit about turbulence along the baffles in the treatment tank.

Izkata 5y ago

Per that Wired article, it was intentionally ignored when the first virus-related research came up in the 1940s because it was too close to the discredited miasma theory. > Given a virus' size and weight, it should be trivial for a physics graduate student to simulate how long it will be airborne. This is also in the article, known research from decades ago. Social distancing is in fact based on a misunderstanding and conflation of a few things in that early research.