The Volokh Conspiracy

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"A Rock … — the More Mass, the Faster It Falls"

Aristotle returns to the Washington Post.

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Prof. Mark Liberman (Language Log) notes this from the Washington Post Friday:

Aerosol researcher and co-author Chang-Yu Wu explained that local humidity and temperature play vital roles in the size of the virus's particles, which can influence its life span in the air. Drier atmospheres in colder regions will induce water evaporation from the particles, shrinking their size and allowing them to float in the air for longer periods. People also tend to seek shelter inside in colder environments and expose themselves to recirculated air that potentially contains the virus.

The air in humid, hotter environments contains more water, which can condense onto the virus particles, make them bigger and theoretically fall to the ground faster. Wu compares the particles to a rock in this case — the more mass, the faster it falls.

Liberman notes that the Wu paper "needless to say, has nothing like the WaPo's 'the more mass, the faster it falls' explanation." (Of course, objects' characteristics can affect the speed at which they fall, for instance because of air resistance, and the behavior of aerosols can be quite complex; but those effects are generally quite slight for "a rock," as our friend from Pisa demonstrated.) Liberman adds:

As often in the interpretation of reported interviews in news articles, the WaPo article leaves us with a problem in abductive reasoning. Did the interviewee really say that? or did the writer (or one of their editors) misunderstand, misremember, or invent it?

NEXT: When Presidents Pick Law Profs

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  1. Well, I mean, it's amusing, but a feather and a cannon ball only fall at the same rate in a vacuum; Sectional density is the name of the game when falling in air.

    Which is why dust falls slower than boulders.

    1. Except if I am reading the quoted section, the researcher in question is talking about how quickly they lose lift/buoyancy and start to fall, not the velocity at which they fall.

      1. if I am reading the quoted section correctly

        1. Blue commenter needs edit button badly.

      2. Distinction without a difference, Matthew. There is no sudden point at which a water droplet "starts" to fall. Gravity is working on it constantly - but so are air currents and random atmospheric fluctuations. A 12" hailstone can be lofted back and forth in the atmosphere - it just takes a lot more than to do the same with a really small water droplet.

        To go back to the original study that Wu was citing, that study assumed relatively still air at average indoor temperatures (low 70s F) ejected at the approximate horizontal velocity of a human sneeze. As expected, larger droplets fell out of the air at shorter distances than smaller droplets. However, the study also assessed how fast the water droplets evaporated. Again, as expected, the smaller water droplets evaporated away to indetectability faster than the larger water droplets (because of the squared-cubed law). The really interesting thing is that when you plot both effects, essentially all expelled droplets either hit the floor (if they were big enough) or evaporate away to nothing within approximately one meter.

        That was the original basis of the 1 meter separation rule used by most of the world in the early covid days. Some US pundit said 'let's arbitrarily double it' and that's where our 6-foot separation rule came from.

        What Wu gets wrong is that colder and therefore drier conditions will increase the evaporation factor while a warmer and more humid condition will decrease evaporation and in extreme conditions could actually lead to an increase in droplet size - but either way, essentially all the droplets still fall out in about that first meter.

        1. Rossami,
          "Some US pundit said 'let's arbitrarily double it' and that's where our 6-foot separation rule came from."
          That is actually incorrect and 10 ft would have been far more prudent.

          1. Show your work, please. Other countries did just fine with a 1-meter (3 foot) rule. I am aware of no evidence that the larger separation distance has had any measurable effect.

          2. That is actually incorrect and 10 ft would have been far more prudent.

            It's actually not incorrect, and the CDC even revised it's own recommendation nearly a year ago (last March) down to a 3-foot minimum.

        2. Again, as expected, the smaller water droplets evaporated away to indetectability faster than the larger water droplets (because of the squared-cubed law). The really interesting thing is that when you plot both effects, essentially all expelled droplets either hit the floor (if they were big enough) or evaporate away to nothing within approximately one meter.

          No virus ladend droplets evaporate to "nothing". Water evaporates. The virus itself doesn't evaporate, and it remains even if all the water evaporates. Other non-water constituents (e.g. salts) also remain. So an infectious aerosol particle remains in the air.

          Because air in a real room will never be still, this very small aerosol particle can remain suspended almost indefinitely. (For small solid spherical particles in air, the setting velocity is V_s ~ ρ_s g d^2/ (18 μ. The 'd' is diameter, and so big particles do fall faster. I've neglected buoyancy because it doesn't matter.)

          Even though these small particles falls, it can be move to the top of the room by any updraft-- including the updrafts created by human bodies that heat air. And of course, air coming out of floor heating ducts creates some locations where air is moving up-- and at a higher rate than the settling velocity of the particle. And as someone in this thread pointed out, if the particle is small enough, they can even be kept aloft by Brownian motion.)

          If there is no method of removing these aerosols, the concentration of particles in the room can rise. In reality, there will always be some air entering and leaving a room either through force ventilation or just leakage. So there will be some quasi-steady concentration of particles.
          Other than qualitatively, I don't think this matters much to the research article. But it does provide an argument why the concentration of virus could remain high when the air is dry, as it is indoors during the winter.

          1. Good point. Explained in the original study (but not in my poor synopsis) is the observation that, generally, infective agents such as virus particles must remain wet to remain viable. Once the water droplet entirely evaporates, the non-water contents can remain suspended in atmosphere but they do little harm.

            Note that this was a pre-covid study of transmission. The research on the relative lack of surface transmissibility of covid suggests that airborne particles would also become non-viable once dehydrated but I don't know of research directly confirming that point.

      3. A better comparison would be mist that hangs in the air versus raindrops that fall. When the water particles are small enough, the eddies of air keep them suspended, but when they get bigger, they begin to fall. However, I can't really fault someone for using an imperfect metaphor in an interview

    2. If the article had compared dust to boulders instead of saying "like a rock" it would have been better.

    3. A feather and a cannon ball, yes, although it's not because of a difference in mass. But the WaPo is talking about two rocks, which will in fact fall at essentially the same rate even in the atmosphere.

  2. How about this?

    When determining settling velocity, the density and particle size are key parameters. Mass is a function of density, so larger particles of a given density will fall faster.

    That IS science, and is well known in the powder handling community.

    1. That may be an observation among the powder handlers. But your explanation has nothing to do with science

      1. Really? Care to think about it?

        The fact is that we don’t exist in a vacuum. Therefore, particles fall through some fluid that has viscosity and density. If the particles are small enough, they are subject to the Brownian motion of the fluid. This is why you don’t see smoke particles travel in a straight line.

        1. You're saying things that have some many buried assumptions, that you don't even realize. That is not physics. And virons on water droplets are not being held up by Brownian motion.
          Nice try, but no cigar

    2. Mass is a function of density

      You have that exactly backwards.

  3. Physics dies in darkness.

  4. The only science that matters is that masks work for everyone all the time, because God Fauci says so. For now.
    Science.

    1. Sub-N95 masks never worked well, nor were they supposed to. There was one study where they may slow the spread 40%, hardly a miracle. But highly useful to stop emergency rooms and intensive care from being overwhelmed.

      I noted later that summer the rhetoric was converting from saving people by wearing masks (and other efforts) to stopping you from getting it to save you.

      This was a political effort.

      Both sides are crap. Shame on them.

      1. 3 factors influence a population’s Covid death rate:
        1. Being in the initial wave
        2. Ability to restrict travel
        3. In 2021 was the population a liberal or conservative population as Democrats continued to mask and got vaxxed (older well off Republicans got vaxxed quickly) and so for example in the SE the major Democratic urban counties tend to have the lowest death rates because they avoided a really bad Delta surge.
        4. An anomaly is young fit populations like Utah and Austin and DC with low death rates because America is generally old and unhealthy.

        Masks aren’t a silver bullet but they clearly mitigate spread to a significant degree and so had Florida just followed Demmings’ lead in Orlando it would have had several thousand fewer deaths…and remember 3000 died on 9/11 and Republicans went insane spending trillions to prevent maybe a hundred more deaths.

        1. "3. In 2021 was the population a liberal or conservative population as Democrats continued to mask and got vaxxed (older well off Republicans got vaxxed quickly) and so for example in the SE the major Democratic urban counties tend to have the lowest death rates because they avoided a really bad Delta surge."

          Arguably they had a good 2021 because their 2020 had been simply horrific. They had higher population levels of immunity, and the vulnerable population had been extensively culled.

          1. Nope, you can break it down by county and Orange County in FL has the second lowest death rate after the Keys which is old population but it can restrict travel. Nice try though. 😉

        2. SC,
          The number of people who believe that masks are worthless is much larger than the number of right wing nutjobs.
          If you watched the Rams v 49ers game in deep blue CA, you would have seen a solid backed football stadium with not a mask over a face in sight

          1. Correct, that’s why in municipalities that had mask mandates during Delta the surge was significantly lower. Masks aren’t a silver bullet but they definitely mitigate spread…so if saving tens of thousands of lives is important to you then you would support non draconian mitigation measures like masking. I don’t support masking in schools and I don’t think one needs to be a Nazi about masking because people die in things like car accidents and bike accidents so I am fine with a certain level of preventable death in our society.

    2. Do you think we will see trials over what these people have done to do many children?

      Hopefully they are just show trials.

      1. Has anyone heard of any class action suit being prepared against doctors. hospitals, pharmacies, medical societies, or state health departments or their goons concerning refusal to allow us to obtain and use therapeutics like IVM? I realize that Fauchi, big Pharma and others are safe from any suit concerning the pseudo-vaccines, but I'm interested in therapeutics.

        1. No, and nobody will.

          Don't you have some doorknobs to go lick?

    3. When I was at UCLA, the only major that did not require even dumbed-down science or math was journalism, probably because a knowledge of the real world could unduly influence reporting.

  5. Humid, hotter environments also naturally have more sunlight and UV radiation that kills the virus. Which effect dominates? Whichever looks worse for red states is what I would guess.

    1. Well, what can I say? Science has a well-known anti-conservative bias. (As does reality more generally.)

      1. Science also tends to frustrate superstition.

        A debilitating double shot from the Republican perspective.

        (If those swinging medallions weren't enough, this might provide some salve for dispirited originalists.)

      2. I love all the Lefty Science that scientists are forbidden to question:

        - Gay parenting
        - Gay animals
        - Transgender animals
        - Transgender children
        - Man-made global warming
        - Man-made global cooling
        - Man-made climate change

        To name a few.

      3. "Well, what can I say? Science has a well-known anti-conservative bias."

        How come you guys can never tell that joke right?

        1. They thought the clown nose was off when it was said.

          1. To be fair, dwb68 had a very silly comment.

            1. The child who pointed out that the emperor had no clothes was not being silly. Neither is it at all silly to point out that the WaPo crowd cares less about science than owning conservatives.

              1. He is arguing that future events in real life that are going to happen worldwide will come down biased against red states.

                He said nothing about the WaPo.

                1. No, that's the sarcastrian spin on his point. His point is actually about your sort of political bias. No matter what the science indicates, the dishonest and political among the Science! community, which includes WaPo, will cherry pick and spin to get the political results desired. It has little to do with the real world and everything to do with the narrative.

      4. Science has a well-known anti-conservative bias.

        If you're goal of paraphrasing Comedy Central tropes is to look like even more of an idiot than you're already known to be then...mission accomplished.

        Yes, I've always been impressed by how science-y the "progressive" anti-nuclear, anti-GMO, anti-vaccine, anti-conventional medicine, et al movements have been...not to mention the breatharians, crystal-worshippers and all of the other flavors of far-left-leaning nut cases.

      5. Science has no bias. It is not a person.

  6. My money is on the person with the humanities degree getting it wrong.

    1. Generally a good bet -- but here, the author of the Washington Post piece is listed as having a BS in Chemistry and an MS in Science Journalism.

      1. "Ocasio-Cortez graduated cum laude from Boston University in 2011 with a Bachelor of Arts degree in both international relations and economics."

        I always found it interesting that a degree in economics is an arts degree.

        1. "Ocasio-Cortez graduated cum laude from Boston University in 2011 with a Bachelor of Arts degree in both international relations and economics."

          An economics degree that led her to conclude, "Unemployment is low because everyone is working two jobs." But she's certainly no Paul "By 2005 or so, it will become clear that the Internet's impact on the economy has been no greater than the fax machine's." Krugman.

      2. I can't fault this journalist too much for getting the science wrong. He has a criminal skull.

  7. You had me convinced up until that last word.

      1. "Journalism", would be my guess.

      2. Sorry Prof. Volokh. Reply failure.

        The evidentiary value of "a BS in Chemistry and an MS in Science" was undone by "Journalism".

        1. Speaking of journalism and standards, imagine the benefit to be derived were Prof. Volokh (or perhaps even -- shudder -- an editor) to devote this level of oversight to the laughably unreliable content of "Today In Supreme Court History" at the Volokh Conspiracy.

          (Guess Who? Here's a nice double shot of Randy Bachman and Burton Cummings, featuring the underrated guitar-flute arrangement.

          Link limits require a prose pointer toward the final minute or so of BTO's Welcome Home, either in the studio or Live at Budokan '76.)

        2. You'll have to whinge louder, Art. Maybe try using all caps or something.

          1. Losers whine, clinger. (See The Volokh Conspiracy, every day.)

            Winners -- that's the liberal-libertarian mainstream in America, for five or six decades of progress -- celebrate.

        3. Aha! Now I get it, thanks; sorry I missed it.

  8. Relativity is the Devil's Workshop!
    Still don't understand...
    OK, I've got a Fishing Pole the length of from Earth to Alpha Centauri, some 4 Light Years away(a measure of distance, not time, but you VC already knew that)
    Let's say the end of the pole is sharpened to a fatal point, against the Common Carotid Artery of an Astronaut on Alpha Centauri(4 Light Years away)
    I give the pole a good 18" jab,
    when does the poor guy on Alpha Centauri get it? ever? 4 bazillion years?
    and no "a 4 Light-Year Fishing Pool can't exist" "Faster than Speed of light is Impossible it's Ein-Stein", it's a "Thought Experiment"
    ala "Einstein"

    Frank

    1. My guess is never. The pole must have billions of tons mass so you can't budge it.

    2. You don't really notice this with a 4 foot pole rather than a 4 light-year pole, but the entire pole doesn't move instantaneously. I don't know how long it would take, but certainly more than 4 years.

      But a shadow can move faster than the speed of light.

      1. How could a shadow move faster than the speed of light? Considering a shadow is the consequence of how light falls on an object, and the light only moves at (you guessed it) the speed of light....

        1. The light moves at the speed of light, but the edges of the shadow can move faster. Think about what happens if you have a really bright light shining at an object ten light-seconds away, and you take one second to sweep an object in front of the light.

          1. Think about what happens if you have a really bright light shining at an object ten light-seconds away, and you take one second to sweep an object in front of the light.

            To an observer at/near the illuminated object in question, the shadow will not appear to be cast on until 10 seconds later. If you're located at/near the light when you pass an object in front if it to create the shadow, it will not appear to you until after 20 seconds.

          2. So, let's assume you're standing at point P, currently in the light at time t<=0. At time t = 0, the light source some distance L away moves such that you will ultimately be in shadow at time T. For all times 0 < t < T, what's going on?

            The light source is emitting photons continuously from it's initial point up until t=0. Photons emitted shortly before t=0 are still enroute to P until enough time has passed that the last photon emitted from the initial light source point arrives at P. So for the observer at point P, they won't even see the light source move until time T, because they're still being bombarded by photons from before the light source moved.

            Since shadow is less light because of an interposing object, the shadow won't actually cover point P until time T, after all the photons from before the movement of the light source have arrived. Ergo, the shadow moves precisely at the speed of light, because it can't move until all the enroute photons have arrived.

    3. I don't know what your pole is made of but because for a fishing pole to be of any use its got to have some elasticity and the 18" of movement will be absorbed by the fishing pole by the time its out of the atmosphere let alone past the moon. And that bend as it goes past Jupiter isn't going to help much either.

      It would be like pushing a rope.

    4. Depends on the speed of sound in the fishing pole, actually, and how lossy it is. If it were made of a perfect diamond crystal, about 67 thousand years.

      1. 66.785 thousand to be precise.

      2. Ouch. My hat off to you, sir. That was terrible.

    5. The nudge would propagate at the speed of sound in the material the rod was made of, and would damp down to nothing very early on.

    6. Interesting thought experiment. Let me modify it a bit to resolve some of the issues below.
      1. Your fishing pole (spear, really) is perfectly stiff and incompressible.
      2. Your spear is sufficiently thin that its total mass is about the same as a regular spear.

      The standard interpretation for relativity says that despite the assumption of perfect incompressibility, your push can propagate down the spear no faster than the speed of light. The poor guy gets it in 4 years.

      However, there are some assumptions (or more precisely, alternative interpretations) coming from quantum theory that talk about effective pairing of particles under certain conditions (such as the handle and the point of the spear) which can effectively transfer information faster than the speed of light. If you can make that work, the poor guy gets it immediately.

      1. "which can effectively transfer information faster than the speed of light"
        Where did you ever get that from. It is a bad rendition of the EIR "paradox"
        You jumbled idea about entangled states of the handle and the tip are nonsense.

        1. This is an interesting conversation, why is you being an ass helpful?

          1. I ask that question of you. What did you find objectionable about pointing out an incorrect interpretation of the EPR "paradoc"

        2. If you think you can do a better job explaining the thought experiment above, feel free to try.

          But, no, I was not thinking specifically of the Einstein–Podolsky–Rosen paradox.

          1. but your comment is the essence of the EPR "paradox" and debate with Bohr. The so-called pair you speak of is that the objects (particles or photons are a single entangled quantum state. Once the state of object 1 is collapsed by a measurement the second object must be in a full determined state. This has been tested experimentally over astronomical distances.
            See https://news.mit.edu/2018/light-ancient-quasars-helps-confirm-quantum-entanglement-0820

        3. "which can effectively transfer information faster than the speed of light"
          Where did you ever get that from. It is a bad rendition of the EIR "paradox"

          Quantum entanglement...and the implication that it might be used to communicate information faster than c...has been a subject of physics since Einstein's days, and has been demonstrated via experimentation. Your attempts to sound more educated than you are fail as nothing but the obnoxious displays of ignorance that they are.

          1. I did use the wrong initials (EIR for a different calculation about general relativity with Infeld and Rosen). Yes, entanglement has been test over astronomical distances. (See https://news.mit.edu/2018/light-ancient-quasars-helps-confirm-quantum-entanglement-0820)
            But the idea that entanglement can be used to communicate information faster than the speed of light is wrong.
            Your attempt to sound intelligent fails.
            As for your insults, grow up.

      2. Generalizing a bit, the push goes through the material at the speed of sound, whatever that speed is. That way, we can eliminate the requirement for perfect incompressibility (which would effectively make the speed of sound equal to the speed of light).

        And if I understand quantum pairing correctly, the current theory is that there is no way to ever use it to transmit information, it only reveals pre-existing information such as matching spin, so causality is maintained.

    7. If you want a serious answer, the answer is 4 light years divided by the speed of sound in the pole's material.

      The speed of sound is a measure of how fast a shock wave can move through a physical object. You don't normally notice this because sound is so fast, but if you push something faster than the speed of sound, it compresses as the shock wave pushes through it to reform. This is, of course, assuming the thing doesn't break, the shockwave of the push doesn't dissipate, and all the other impossible things in your setup stay still long enough for the millions of years needed for this to complete.

  9. Isn't acceleration due to gravity, precisely speaking, due to the mass of both objects in the equation? So wouldn't the statement technically be correct, even if it wouldn't be observable without special equipment?

    1. It wouldn't be observable even *with* special equipment, unless the rock is rather unreasonably large.

      1. You're underestimating how small of forces can be measured. Cavendish measured the force of gravity between two masses in a lab in the late 1700's. Today you can measure the photon thrust from a small LED fairly easily, using a similar technique.

        1. Brett,
          good try. You're correct about force measurements.
          But I did not describe making a force measurement, but a timing measurement of falling bodies. In that experiment the measurement would have been very difficult with the limit being given by the resolution of the best streak camera that one can make (at the tens of femtosecond level).

    2. More mass = more gravitational force. More mass also = harder to accelerate.

      Mass doing this double duty means that it cancels itself out under Newtonian conditions, leaving a constant gravitational acceleration regardless of mass.

      Einstein thought this was suspicious.

    3. The mass of both objects, multiplied, does give you the force involved.

      The acceleration is the force divided by the inertia.

      The inertia, by a coincidence so weird that it inspired general relativity, is the same as the gravitational mass (confirmed experimentally to within 10 parts per quadrillion: https://physics.aps.org/articles/v10/s133#:~:text=MICROSCOPE%20tests%20the%20equivalence%20principle,a%20long%20period%20of%20time.&text=Two%20independent%20electrostatic%20feedback%20circuits,is%2C%20on%20the%20same%20orbit.). So the acceleration, other things being equal (like being in a vacuum) is the same.

    4. The increase in gravitational attraction (which isn't even real, as gravity is really just a function of mass's interaction with spacetime) is nullified by the corresponding increase in inertia.

  10. Which weighs more: a pound of feathers or a pound of lead?

    1. They weigh the same, of course. But a pound of gold weighs less.

      1. Now do a ton of feathers and a ton of gold.

        1. A ton of feathers is heaver than a ton of gold, of course, just like an ounce of feathers is lighter than an ounce of gold.

          1. This answer is rightwing hysteria!

          2. Michael P, did you check that out before you answered?

            1. Why don't you take hobie aside for a little chat instead?

          3. A ton of feathers is heaver than a ton of gold

            Since you seem to be inventing the Troy ton you can make it heavier or lighter whichever you prefer.

            1. It would be pretty irrational for it to be anything but 2000 or 2240 pounds Troy, and 2240 pounds Troy is less than 2000 pounds avoirdupois, so a ton of gold would weigh less than a ton of feathers under any combination of those choices.

              1. It would be pretty irrational...

                You must think the number of grains in a Troy ounce and ounces in a Troy pound are irrational. Why shouldn't the newly-minted Troy ton be at least as unconventional?

  11. What if it wasn't a rock, it was a rock lobster?

  12. For objects falling in air, for objects of a given size, the more mass, the faster they fall.

      1. Congratulations on being as ignorant as Lathrop and not comprehending something as simple as density (which is rather ironic).

        Now explain why a rock dropped into water (which is a fluid, like air is) sinks, while an astronomically more massive supertanker floats.

        1. "density" above should have read "sectional density".

    1. Easy to test. There's a novelty buy, a set containing an aluminum cube (light) and a tungsten cube (about as heavy as gold) of the same size. Find a safe place to drop them, see what happens.

    2. Close but not quite. Not only does the size (that is, volume) matter but so does the orientation. The terminal velocity of a piece of paper oriented "flat" to the ground (think parachute) will be much lower than the terminal velocity of the exact same piece of paper oriented vertically. What matters is the 'cross-sectional density' - that is, mass divided by the area of the object (measured perpendicularly to the gravitational vector), not the mass divided by the object's volume.

      1. In addition, one has to account for bouyancy

      2. Apologies. I knew I had a small mistake in that when I wrote it yesterday but couldn't figure it out at the time. The last parenthetical should have read "measured perpendicularly to the direction of travel".

    3. For a small ball bearing and 16 kg weight, you would be extremely hard pressed to measure any difference.
      The only differene can come from air drag which in this case would be negligible.

      1. Those would not be two "objects of a given size".
        Try a bowling ball and a same-sized balloon.

        1. Try dropping a bowling ball-shaped object made of lead, and one made of aluminum. I doubt you could measure a difference in their velocity.

          1. The lead ball will have a terminal velocity roughly double that of the aluminum one, so if I let them drop long enough the difference will be easily apparent.

            1. I don't think terminal velocity is what anyone immediately thinks when asked how fast will an object fall, since for most objects in most scenarios that don't involve tossing things out of airplanes, terminal velocity is never going to be achieved.

              1. I'd expect a five storey drop would be plenty high enough to detect the difference.

              2. Here's a vid of various things getting dropped in pairs, with microsecond timings from analyzing the video frames. There are a number of peculiar results. If you watch to the end they explain the math.

                The drop looks to be 50 ft or so. Some of the smaller objects reached terminal velocity, some of the larger ones didn't. I especially liked the lemon vs. watermelon ... spherical cows have their limitations.

                1. They (makers of the video) seem to have chosen a lot of drop comparisons that features one object so light that it would approach buoyancy in a strong wind, and another object which is nowhere close to that point. I mean, yes, if you select for objects where terminal velocity is quickly reached, 50' is plenty of distance. (In fairness to your video authors, they're interested in things where terminal velocity is achieved during short fall intervals).

                  My proposal was a 'bowling ball' made of different materials. I doubt 50' is enough to detect a difference between aluminum and lead. Aluminum is less dense than lead, but it's still almost 3x the density of water.

        2. Well there is also buoyancy as Armchair Lawyer mentioned above. For dense objects not much of a factor. For a balloon a much bigger factor, filling with helium or hot air will make it not fall at all.

        3. This is the place for a true story about a former employee (and former Marine).
          Some time ago, near Thanksgiving, he jumped out of an airplane over rural Illinois hold a moderately large pumpkin. The both traveled toward the ground together, until he pulled the ripcord. As seen by him, the pumpkin rocket toward the ground where it plunged through the roof of a house and "exploded" in the kitchen.
          Fortunately no one was in the kitchen. Like a good Marine should he turned himself in to the police.

          1. At least it wasn't a turkey.

  13. I can forgive the fact that people think bigger things fall faster than smaller things; air resistance does matter.

    What I really cant forgive is that now that I've read the paper*, neither the WaPo journalists nor the authors interpreted their own data correctly. Set aside the fact that there are numerous problems with this "study" starting with the fact that they use time series analysis on data including the 2020 period before we had a lot of testing.

    Reading the paper very carefully, all I can conclude from their study is that when people move indoors, they get covid more. There are a few places where they state this. For example,
    "In warm regions (Figure 5A), a large number of cases were clustered at high temperatures than otherwise,with the opposite for cold regions (Figure 5B)."

    The bury the conclusion deep in the conclusions section.
    "That is, if the temperature range is either less than 17C or greater than 24C,the region will have a higher probability of occurrence of COVID-19 than average cases reported in the region. A pattern of decrease in number of COVID-19 cases when the ambient temperature is within the range of 17–24C and increase when the temperature is out-side this range, strongly suggesting seasonality in COVID-19 in both warm and cold regions. For example, during winter, if a region experiences ambient air temperatures below 17C, an increase in COVID-19 cases would be expected. Similarly, during summer months, if the ambient air temperature is higher than 24C, an increase in COVID-19 cases would be expected. If cold regions do not experience temperatures.24C, they should expect high numbers of cases in the winter. On the other hand, if a warm region does not experience temperatures,17C during the winter months, a peak in cases would occur only during summer. Regions that experience both, temperature extremes (i.e.,.24Cand,17C) will likely have two seasonal peaks of COVID-19 cases
    "

    NEWS FROM THE DEPARTMENT OF ITS OBVIOUS: WHEN YOU MOVE INDOORS PEOPLE ARE CLOSER TOGETHER AND MORE LIKELY TO GET COLDS AND THE FLU.

    If hot regions, that happens when the A/C needs to come on.

    It has absolutely nothing to do with their big fancy meme in Figure 6. And to call it a meme based on this data is generous. Or Newtons Law of Gravity.

    *which by the way is really hard to read. I had to parse it three times. Keep in mind I read this kind of stuff every day.

    1. Honestly I read this paper and wondered how it took eight people to do work this bad.

      1. If they'd had fewer people it just would have taken longer to get work that bad.
        Unless they were politicians.

    2. In my experience, once a "science journalist" gets done translating a technical concept for everyday people, half the time they've got things backwards.

      1. The fundamental problem is that the technical report needed to be translated in the first place. I found it very difficult to read. What the hell is the point of knowledge if you cannot communicate it to people? A paper that is inscrutable or opaque is just intellectual masturbation in my book.

        1. What the hell is the point of knowledge if you cannot communicate it to people? A paper that is inscrutable or opaque is just intellectual masturbation in my book.

          Indeed. This sort of inner-circle hotshot mentality pervades most disciplines: science, law, medicine, even coding (where the saying literally goes "if it was hard to write, it should be hard to understand").

          There are of course times where you necessarily need to get into the weeds, whatever the area. But in general, a paper that a reasonably educated person can't readily follow is the fault of the writer. And that makes the persuasion value plummet quickly, as you've noted here.

    3. Honestly, even the abstract is unreasonably convoluted.

      I'm sad when someone could just make an allusion to Goldilocks to quickly summarize the major finding, and it would be 100x clearer than what was actually written.

  14. Dr. Wu's statement is correct so far as it goes. More massive drops do fall faster than less massive, for the same reason that a big rock falls faster than a little one. We can talk about air resistance, etc., some other time.

    1. >a big rock falls faster than a little one

      The point is that it doesn't, unless the little one is so small that air resistance is important, and that this should be so much part of common knowledge that nobody should be saying it in a science article.

      Shoulda stuck with true things that people see every day, like drops from their plant mister falling down quickly and tiny dust motes drifting in sunbeams. Just remind people they've seen it, and you don't have to try to explain aerosol physics.

    2. "a big rock falls faster than a little one. "
      Wrong.
      Tell that to Galileo.
      Better still do the experiment yourself with a 1 lb stone and a 10 pound stone.

      1. Um, wouldn't that be Sir Isaac Newton not Galileo?

        1. Unless Sir Isaac Newton made a trip to Italy to drop some objects off the leaning tower of Pisa... no.

    3. Galileo called...

      1. Throw a fistful of little stones into the wind on a windy day and get back to me after you’ve picked them out of your beard.

        1. Throw a fistful of little stones into the wind on a windy day and get back to me after you’ve picked them out of your beard.

          Uh...you're the one who said, "We can talk about air resistance, etc., some other time."

    4. Dr. Wu's statement is correct so far as it goes. More massive drops do fall faster than less massive, for the same reason that a big rock falls faster than a little one. We can talk about air resistance, etc., some other time.

      So he's correct if one assumes away that which actually exists.

      Brilliant.

  15. The sizes don't matter.
    The weights don't matter.
    The humidity doesn't matter.
    The temperature doesn't matter.
    All that matters is that this was in the Washington Post, therefore it is wrong.

  16. There's nothing wrong with the statement. The regime in question is one of low Reynolds number, to which the freshman physics result that a = g does not apply. A reasonable estimate would use Stoke's law for the drag which goes like R (radius of the particle), and of course the force of gravity goes like R^3, so not surprising the bigger you are the faster you fall.

  17. Hey, if Neil Young is letting us read it, it must be accurate.

  18. Reporting in general has gotten very fuzzy & less careful about editorial niceties & accuracy. And science reporting often borders on embarrassing. I would not put much stock in the reporter being careful about the quote, or the understanding.

  19. On another note.
    I keep thinking that edited sections of the threads here would make a very good theatre piece (or even series). People would be encouraged to play themselves.

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