COVID-19 March 19, 2020

A couple of important changes with this update. First, going forward, I will provide an analysis using only the prior day's data. I've had to make this change, because the CDC releases info at noon (EDT) and those data are woefully incomplete and behind compared to the reporting from the individual state health departments. As soon as the day's numbers from the CDC hit the street, they are already obsolete. For example, yesterday's numbers ended up at 8,058 cases, whereas the CDC report from yesterday showed only 7,038.

Second, I am now using wikipedia as a data source, which in turn posts data directly from the state health departments. See here and here. These data are continually updated in near real-time, and are verifiable by going straight to the state health department websites that are given as references for the data.

So, today's update is really a reanalysis of yesterday, but using more accurate and complete data. There's no point in looking at what the CDC will say later today, because the data are still pouring in, and will be continuing to do so until late until the evening. I'll look at those final numbers and report on them tomorrow.

Below is the analysis based on data valid for yesterday (click on the image for hi-res).

As I indicated above, the actual number of cases (8,058) was far above what the CDC had reported at noon (7,038). Including this more accurate data drives the short-term trend line (orange) closer to the long-term trend (blue). I can't be certain, but I strongly suspect that effort to increase testing is starting to show. Still, the number of suspected cases far outweighs the current testing capabilities. As capabilities increase, I expect the short-term trend to approach and then actually surpass the long-term trend. It seems very likely that the slight dip over the last few days was due to systematic bias in testing, and not a true deceleration of the exponential growth.

The short-term trend line is predicting 10,129 cases by the end of the day. That is likely to be low compared to reality and indicates that the short-term trend is indeed suffering from systematic data bias. Using either the short- or long-term trend, the data predicts that we will hit 100,000 cases around March 26, plus or minus a day. This is 10x the current number. If things continue, we will hit 1,000,000 a week later. The 100,000 number is nearly a sure bet. There's nothing we can do about it because the people that will be diagnosed are already infected. If significant actions are taken, there's a chance that we can have an impact on the 1,000,000 two weeks from now. It will be interesting to see if the patchwork of half-assed local and state policies will show any effect; it's going to take more than a week to assess that.

Flattening the curve is a popular meme right now. Below is an analysis of the progress, or lack thereof, in doing so (click on image for hi-res). The graph shows the daily change in new cases. For algebra buffs, each data point shows the slope of the curve in the graph above for each day. For calculus buffs, it's the derivative of the curve above. If the number of cases was to remain the same as the day before, the line connecting two data points in the above graph would be horizontal. Horizontal lines have a slope of zero. Clearly, that's not the case. The line is not horizontal. It has a positive (and large) slope. Right now, the number of cases each day is increasing exponentially, and the slope of the line is getting larger and larger, which is why the line in the graph below is going up. In other words, the curve is not flattening at all. A flattening of the curve would mean that the data in the graph below would start to fall and head toward zero. A value of zero, however, indicates only that the number of cases isn't increasing or decreasing each day. Ultimately, we want the number of new cases each day to be lower than the day before. That would imply a negative value (below zero) for rate of change. We've got a loooonnnnggggg way to go before that happens.

The fate of all these curves depends exclusively on the collective actions of individuals. We must all do our part. Do not go out in public unless it is absolutely necessary. The CDC recommends no groups larger than 10. This is inadequate. Groups no larger than 1 should be avoided. In other words, no groups!

I continue to receive information from my doctor and nurse friends working at local hospitals. They are already running out of beds, supplies, personal protection equipment, and everything else that is necessary to treat the infected. We're only at 10,000. Next week it will be 10x worse, and the week after will be close to 100x worse. The system will likely have exceeded its breaking capacity. Nobody knows what will happen then. There is no plan. In Italy, patients were left to die. It's hard to imagine a different outcome here. Each of our individual actions can make a difference. DO IT.

EDIT:  CDC Website now says the following:
"In the event of a discrepancy between CDC cases and cases reported by state and local public health officials, data reported by states should be considered the most up to date."  The data above are from the state and local public health officials, as indicated.

COVID-19 March 18, 2020

CDC just put out their numbers based on reports from yesterday: 7038.

Today's graph hasn't changed much from yesterday. Note that yesterday's numbers have been adjusted slightly (upward) to account for reports that trickled in late. Today's 7038 will likely be adjusted slightly upward tomorrow.

Based on the orange trend line, we will come in just a little bit under 10,000 tomorrow. For reference, we crossed 1000 on the 11th. So, a 10-fold increase in one week. If the trend continues, we'll be at 100,000 at this time next week. The actual number of infections is probably 10 to 100 times larger.

Medical services are really starting to feel the pressure. I get this info directly from personal contacts I have working at the hospitals on the front lines. If that's what happens at 10,000, imagine next week at 100,000. PLEASE BE RESPONSIBLE and KEEP YOUR DISTANCE. Mortality rate from this is anywhere from 1-5% on average, and much higher for older and higher-risk persons. I'll let you do the math. (What is 5% of 10,000? What is 5% of 100,000? What is 5% of 1,000,000?)

All data except for today is coming from: https://en.wikipedia.org/wiki/2020_coronavirus_pandemic_in_the_United_States Today's data is from the CDC: cdc.gov/coronavirus/2019-ncov/cases-updates/cases-in-us.html

COVID-19 March 17, 2020

Today's numbers are in. I've updated the analysis a bit. I'm now showing all the data (blue) and the data for the last 10 days (orange). The trend line from the orange data will be more responsive to shorter-term changes. The good news is that the orange line is below the blue, although that could be a statistical aberration or the result of systematic issues with testing and reporting (likely). The bad news is that either line is bad news.

The Cognitive Dissonance of Sam Harris

In “The Moral Landscape”, Sam Harris argues that morality can be determined by considering the impact of actions on social well being.  The impact is quantifiable through the relative comparison of possible social states arising from different actions.  A moral action is one that produces the greatest relative maximum in the topology of possible states of societal well being.  Let us take this definition of morality as an axiom.  For the purposes of this piece, it matters only that Sam Harris believes it to be true not that it is true. 

Now also consider Sam Harris’ position on guns.  He argues vociferously for the right to own guns.  Lots of them.  Of many kinds.  For example, in his “The Riddle of the Gun” he writes:

“Wouldn’t any decent person wish for a world without guns? In my view, only someone who doesn’t understand violence could wish for such a world. A world without guns is one in which the most aggressive men can do more or less anything they want. It is a world in which a man with a knife can rape and murder a woman in the presence of a dozen witnesses, and none will find the courage to intervene.”

This is, of course, a strawman argument.  Few are calling for a world without guns, although it is reasonable to ask whether such a world would be in a state of greater well being than a world where guns are ubiquitous.  Does it really follow that in a world without guns that a man with a knife can rape and murder?  Are law abiding citizens really helpless in a world without guns?  Do we see women being raped and murdered across Western Europe where guns are generally far less common than in the U.S.?  Is crime rampant in the UK where not even the police carry firearms (except for Ireland)?  And, couldn't non-lethal methods be used?  How about tasers or pepper spray?  Are guns the only defense we have against violence?  It's a strawman and a false dichotomy.

The reality is, reasonable people are calling for greatly limiting access to firearms or removing certain types of firearms from society.  Is the resulting scenario a state where well being would be increased?  Suppose only law enforcement carried firearms so as to protect law abiding citizenry from violence.  Would this result in a state of higher well being than we have now?  Conversely, would well being be increased by increasing the number of guns and allowing nearly everyone to carry multiple firearms at all times? 

Measuring well being is subjective, so reasonable people might disagree over whether one possible outcome is better than another.  However, it seems that in the spectrum of possible states of well being, a society in which there were no guns, or at the very least, a society where only law enforcement carried firearms would be better off than a society where guns flow like water.  And a society with non-lethal weaponry might be yet an even higher state of well being.

Sam Harris’ moral landscape position seems incompatible with his stance on gun control.  He has provided all sorts of arguments to support his position on guns, but interestingly, he has not yet, as far as I know, argued his position in terms of the moral landscape.  If morality can indeed be quantified by testing actions against their effect on well being, then Harris’ best argument for guns would be to show that a society armed to the teeth is better off than a society without firearms.  Good luck with that one, Sam.  I suspect that in the end, you'll have to choose either guns, or the philosophy of the moral landscape, or reject both.  But you can't have both guns and the philosophy of the moral landscape.

  

What Causes Hurricanes (and Some Mars Dust Storms)?

It's not uncommon that I hear incorrect explanations for the origin or behavior of various atmospheric phenomena.  This post was inspired by a recent event where an individual insisted that "extreme pressure variations" are needed to produce a hurricane.  Below, I describe the actual mechanisms that produce a hurricane.  It turns out the same physics may also be responsible for producing some Mars dust storms.

Consider first a motionless atmosphere with no horizontal pressure variations at all.  That is to say, there is no wind and if you were to look at a weather map you would see no high or low pressures.  It is from this state that hurricanes (also known as tropical cyclones) develop.  Immediately, you can see that if this is indeed the initial scenario, then the assertion that "extreme pressure variations" are necessary is exactly wrong.

In reality, there is no such idealized state in the atmosphere.  There is always some amount of pressure variation and therefore some amount of wind.  The process I will describe below works just as well as long as these winds and pressure variations are small.

From this rather boring initial state, heat a chunk of air near the surface from the sun.  It becomes buoyant like a hot air balloon, and rises.  In the tropics, it is not unusual that such rising motion will develop into individual thunderstorms.  Inside a thunderstorm, water vapor condenses, which releases heat.  This heating causes the air to expand.  (Slightly technical here: this is an adiabatic expansion, meaning that no net energy is being added; even though there is heating due to condensation, it is internal heating and represents no external energy input).  This expansion has the effect of causing a weak low pressure to develop near the surface and weak high pressure to develop aloft.  Once there is a low pressure at the surface, horizontal winds develop and begin to flow toward the storm.

If the thunderstorm is over water, the wind now flowing toward the storm interacts with the underlying ocean.  The interaction is actually quite complex, but I'll distill the essential and relevant parts here.  If the ocean is warmer than the air, the air will be heated through turbulent eddies transporting the heat of the ocean upward.  The strength of the turbulent eddies and therefore the efficiency of the exchange is related to the wind speed and the difference in temperature between the atmosphere and the ocean surface.  If the wind is strong (all other things being equal) the exchange will be strong.  If the temperature difference is strong (all other things being equal) the exchange will be strong.

In the case we have so far, the winds are rather weak, so the exchange is rather weak.  Nonetheless, energy is being added to the atmosphere and carried toward our thunderstorm. (Actually, it is entropy that is being transported, but it's not important at this level of discussion, and I digress...)  As the air flows toward the weak low pressure, it expands.  Normally, this expansion would cause cooling.  However, the warm ocean underneath keeps the temperature of the air nearly constant as it expands.  In other words, the heat the air receives from the ocean nearly balances the cooling due to expansion.  This is called an isothermal (same temperature) expansion process.

Once at the storm, the air rises, condenses, and heats the atmosphere.  This strengthens the low pressure at the surface.  In turn, this increases the wind speed flowing toward the storm.  And this in turn increases the heat exchange between the atmosphere and the ocean (recall that the magnitude of the exchange is related to the wind speed).

It should be clear that what we have is a feedback process.   It's a process that reinforces itself.  As more energy is picked up by the air flowing towards the storm, the more heating is produced in the storm, the lower the pressure drops, and the stronger the winds get.  If you look at the entire system of air flowing toward the storm, air rising in the storm, air flowing out of the storm aloft, and then sinking away from the storm, you have a complete cycle.  Approximately 30 years ago the thermodynamics of this system was recognized in two landmark papers (you can get them here and here).  It turns out to be a sort of Carnot engine.  The process was called "Wind-Induced Sensible Heat Exchange", because it coupled the wind to the exchange of heat energy with the ocean.  While the fine details of this mechanism are still being debated in the literature, the overall process is now well established.   In essence, the engine extracts heat from a source, in this case the ocean and turns it into mechanical work (in this case increasing wind speed).

For simplicity sake, I've left out a lot of details, but these are not relevant to the big picture here.  There is at least one detail that is relevant:  The Earth rotates.  This means that as the air moves, it will experience an apparent deflection.  If the movement is over a sufficiently long time, this will result in the air beginning to rotate around the low pressure rather than flowing toward it.  If nothing else were to happen, there would be no air flowing to the storm, just going around it.  That would be the end of the storm.  But, there is friction.  Friction keeps some component of the motion always flowing toward the low pressure.  Thus, the feedback process may continue.  Furthermore, because friction is also a function of wind speed, the strong the winds, the stronger the friction, which dictates how much energy can flow to the storm.

The above process is the basic concept of how hurricanes develop.   No "extreme pressure variations" are needed.  The storm can develop from a completely motionless  atmosphere with no pressure variation at all.  It actually depends on the lack of an initial pressure variation.

Why don't all storms develop into hurricanes?  There's lots of things that can mess up the feedback process.  One is that the system moves over land.  Then there is no heat exchange with the ocean.  Another is that the initial storm can be too close to the equator.  The deflection of winds at the equator is zero, so no rotation can develop.  If the storm moves to higher latitudes, the ocean can become too cold and this limits the energy that can be provided.  Another major hindrance to storm formation is the presence of strong wind shear.  Wind shear is a change of wind speed or direction with height.

Here's the thing about wind shear:  Wind shear results when there are strong pressure variations.  For example, the jet stream is a result of strong large scale pressure differences.  Hurricanes and jet streams just don't get along.  The strong winds that result from the strong pressure differences literally rips the hurricane apart by shearing the top of it off.

Not only do hurricanes not form because of extreme pressure variations, they are prohibited by extreme pressure variations, because such variations produce wind shear.

Obviously, once a hurricane forms, it has strong pressure variations related to the storm itself.  This is not what causes the storm however.  The strong pressure variations are a result of the storm, not the other way around.  The hurricane is produced by the Wind-induced Sensible Heat Exchange--a process that transfers heat from the ocean to the atmosphere.  The process depends upon having a relatively flat pressure field for it to start and proceed.  Again, if extreme pressure variations are present the associated wind shear will disrupt the entire process.

I mentioned early on that a similar process may  occur in some Mars dust storms.  I published a paper about this a couple of years ago (here).  Dust essentially provides the heating on Mars.  As air flows toward the storm, dust is lifted, and that dust is radiatively heated by the sun.  Winds increase in the disturbance and this causes more dust to be lifted.  Thus, I named the process Wind-Enhanced Interaction of Radiation and Dust (WEIRD)  in recognition of the WISHE analog to hurricanes.

A Short Lesson in Thermodynamics as it Relates to Life

I was recently presented with the statement that “life is the only force that counters entropy”. This can be taken to mean one of two things. The first is that life results in a net decrease in entropy.  The second is that while life may result in a net increase in entropy, entropy of the life form itself is reduced and life is the only such system that can do this. The first argument is nonsense, as it violates the 2nd Law of Thermodynamics.  The second statement is just plain false; there’s nothing thermodynamically unique about life. Let’s look at both situations to understand why.

The first order of business is to define entropy. There are lots of valid definitions and all valid definitions can be shown to be equivalent. One definition of entropy is the amount of energy that cannot be used to do work. Doing work requires energy. For example, if you want to move something, you need to expend energy.  Except for theoretical systems, whenever energy is expended by a system, some of the energy is wasted—not all the energy can be used to do work. For example, when you move an object, you expend energy to flex your muscles, and this is translated into kinetic energy (energy of motion). As your muscles flex, heat is created. This heat is sent into the environment and is not used to move the object. Thus, entropy is increased in an amount related to the wasted energy.

The inefficiency of systems that do work is at the crux of the 2nd Law of Thermodynamics. In a theoretically perfect system, all the energy would go to do work and no heat would be generated. a perfect system can at best use all energy to do work (resulting in no net decrease in entropy). An imperfect system (e.g., a real world system) will have an inefficiency so that some energy is wasted. The wasted energy produces a net increase in entropy. No system can do work to produce more energy than is needed to do the work. This would be a perpetual motion machine and it would generate a net decrease in entropy.

We can now investigate whether life counters entropy. The answer is no, at least not in the global, net sense. Life can do work (e.g., grow, reproduce, move, etc.), but all these processes involve an inefficient expenditure of energy. Life increases entropy. Period.

Now let’s look at the second possible meaning of “life is the only force that counters entropy.” To do this, let’s consider a different, but equivalent measure of entropy. Entropy is also a measure of organization (or disorganization). A system that moves toward more order has a decrease in entropy. The existence of such a system may seem impossible given the discussion above, but it is not. A system can have a decrease in entropy at the expense of its surroundings. The surroundings will suffer a larger increase in entropy than the decrease in the system, resulting in an overall increase in total entropy. There are a multitude of examples of systems in which entropy is decreased.

Life is indeed one such example. Cells and organisms are assembled from a more disorderly system of atoms and molecules. Life takes in nutrients and assembles these into orderly functioning life systems. So, in this sense, one could say that life counters entropy. This of course ignores that life, on the whole, actually increases entropy when life plus its environment is considered. The outstanding question is whether life is the ONLY system to do so. The answer is clearly and resoundingly, “no”.

Well known examples of systems that have a reduction in entropy are air conditioners and refrigerators, crystal formation, and planet formation. The true list of such systems is possibly infinite. Air conditioners produce cold air from hot air. The cold air is slightly more ordered than the hot air. Entropy decreases. But this is only true if the waste heat is neglected. Anyone that has spent even a small amount of time around an air conditioner knows that in order to produce cold air, hot air—much hotter than originally ingested—must be
ejected. So, in net, entropy increases. Entropy is lower in the cold air, but it is higher in the hot air, and the net effect is an overall increase in entropy. Crystals are very orderly. This order represents a reduction of entropy compared to the original unorganized, uncrystalized molecules. But, as in the previous example, the environment suffers a larger increase in entropy in order to allow for crystallization. Cyrstalization generates waste heat and, therefore, an increase in entropy. The net change in entropy is positive. Solar Systems form from a collection of gases and dust. These spiral in and accrete into larger bodies, eventually becoming planets—a more orderly arrangement. But, this process generates heat, and the entropy generated from solar system formation exceeds the reduction in entropy associated with greater organization.


So, there you have it. The first interpretation is wrong and the second interpretation is wrong. Life does not counter entropy, at least in the global sense. Life increases entropy. The second interpretation is wrong even if life is viewed in isolation from its surroundings. In such a situation, life produces a reduction in entropy in the isolated life system, but there is nothing unique about this process. Lots of systems, in absence of their environment, constitute a reduction in entropy. Life is not the “only” system to do so.

Making a statement such as “life is the only force to counter entropy” is at best misleading, because it implies that life has the overall effect of decreasing entropy. It can’t do this, because of the 2nd Law of Thermodynamics. If the proponent of such a statement tries to hide behind the canard of only talking about the system in isolation, they will find themselves once again in the wrong corner, because life is not in any way unique in this regard. In short, there’s nothing thermodynamically special or unique about life.

The Death of Planets

The Death of Planets.  No, not the planets themselves.  The idea or concept of what we have recently called planets is doomed, with the demotion of Pluto to a dwarf planet being the most recent step in a process that began with Copernicus.  Then end game will be the realization that the concept of a planet as a meaningful astronomical class of objects is antiquated and archaic.  The concept of planet is no longer compatible with what we know about the Universe.  The bickering by a minority of astronomers about the definition of a planet, and which has achieved tremendous exposure in the public arena, is as pointless as the flat Earthers arguing about whether the flat Earth is rectangular or circular. 

Since humans first looked up at the night sky, they noted that there were some objects, often brighter than the rest that did not follow the other objects in their regular movement across the sky.  The ancient Greeks labeled these objects as “The Wanderers”, or as we know them, planets.  Thousands of years ago, the segregation of these special objects from the rest of the celestial chaff made sense; they were clearly different than all the lights in the night sky, and there was no mistaking what was a planet and what was a star.

       The path of Mars against the fixed stars as viewed from Earth. Click on Image to see animated version.  (Image Source: Unknown) 

Then came Nicolaus Copernicus (19 February 1473 – 24 May 1543) and Galilei Galileo (15 February 1564 – 8 January 1642).  In less than a century, the crystalline spheres upon which the stars rode and the Ptolemic epicycles that described the motion of the planets, came crashing down.  The wanderers were in orbit about the Sun, not the Earth, and they were not just points of light, but other worlds.  Some like Jupiter, had moons, just like Earth.  Luna, the Earth’s moon, had mountains and craters.  And there was more, much more.  The skies were crowded with stars that could not be seen with the naked eye, but which revealed themselves through magnification (this includes nebula and galaxies which could not be easily distinguished from individual stars back then).  The origin of the “milkiness” of  the Milky Way became obvious—it was composed of stars, packed so closely together in such great density that they appeared as a hazy cloud. 

Until 1781, the number of known planets remained at six, all of which could be observed by the naked eye without the aid of a telescope (Mercury, Venus, Earth, Mars, Jupiter, and Saturn).  Sir William Herschel discovered Uranus in 1781.  Neptune was discovered by a Ph.D. student, Johann Galle in 1846, based on predictions provided by Urbain Le Verrier, which explained the small orbital perturbations of Uranus.  The search for a ninth planet (at the time needed to explain additional perturbations in the orbits of Neptune and Uranus, but no longer needed now that the masses of the previous eight planets are better constrained) was ended in 1930 with the discovery of Pluto by Claude Tombaugh.  Pluto was a bit of an odd planet.  It was very small, but more importantly, it orbited in a plane about the Sun that was significantly different than all the other planets.  Neither Uranus, Neptune nor Pluto can be seen without a telescope.

The orbits of the classical planets about the Sun.  All but pluto orbit in nearly the same ecliptic plane. (Image Source: Unknown)

Oddly enough, what we now call an asteroid named Ceres, was discovered in 1801 by Giuseppi Piazzi.  Like the other known planets at the time, it was a wanderer, in orbit about the Sun between Mars and Jupiter.  By all accounts Ceres was a planet, and although not known at the time, it was spheroidal like a planet.    Indeed, it was considered a planet at the time of its discovery.  Within a year or two, the inner Solar System began to get a lot more crowded.  Pallas, Juno, and Vesta were discovered, also in orbit about the Sun between Mars and Jupiter.  It was not long before dozens and dozens of these objects were found.  By the turn of the century, there were hundreds.

The known objects in the inner Solar System, including asteroids (white) and trojans (green).  Hundreds of additional objects are discovered every year.  (Image credit: Unknown; data source: Minor Planet Data Center).

For no other reason than their location between Mars and Jupiter, these objects which had all the same orbital properties of the classical planets, were put into a new class of objects, called asteroids, as suggested by Sir Herschel (the discoverer of Uranus).  However, for many years, the terms planets and asteroids were used interchangeably in the scientific literature.  By the time thousands of the objects had been discovered, the need to distinguish within the literature the classical planets from these minor planets led to the acceptance of the term asteroid (as well as minor planet), which has remained to this day.  Importantly, at the time, the distinction between asteroids and planets was merely one of convenience. 

Asteroid and former planet Ceres, as viewed through the Hubble Space Telescope by my friend and colleague J. Parker at Southwest Research Institute.  Ceres is massive enough that its shape is spheroidal.  (Image credit:  NASA)

For more than a hundred years after the discovery of the first asteroid, Ceres, the known objects in the Solar System consisted of the Sun, the classical planets and their moons, the asteroids, and the occasional comet.  Then, suddenly, the population of the Solar System once again exploded.

Dave Jewitt and his former graduate student Jan Luu found the first Kuiper Belt Object (KBO) in 1992.  KBOs are found outward from the orbit of Neptune to ~55 AU.  Pluto is within this region and is one of the  largest KBOs.  Thousands of these objects are now known to exist, including Eris, which is thought to be slightly larger than Pluto, and Quaoar, Makemake, Haumea, and Ixion, all of which are at least half as large as Pluto.  Pluto is not alone in the outer Solar System, nor is it unique. 

 Known Outer Solar System Objects consist mainly of KBOs. (Image source: Unknown; Data obtained from Minor Planet Center).

Beyond the Kuiper Belt there has been theorized to exist the Oort cloud, filled with additional icy debris left over from the early formation of the solar system.  It is from the Oort cloud that comets may originate.


We now know (thanks to increasingly powerful telescopes and spacecraft exploration) that objects in the Solar System come in a remarkable variety of shapes, sizes and compositions.  The classical planets are all spheroidal.  The inner planets and asteroids are rocky.  The outer planets are gaseous or liquid metal.  The KBOs are icy (probably mostly methane and water ice).   The largest of the asteroids and KBOs are also spheroidal; this an inescable consequence of physics—at some point an object becomes large enough that its self gravity causes it to collapse upon itself and reaches so-called hydrostatic equilibrium.   At the very small end of the size distribution, we know there exist small grains of dust.  Thus, the Solar System is populated by objects smaller than a dust grain and as large as the Sun with a continuum of objects in between.

Asteroids can occasionally present a hazard to the Earth (just ask the dinosaurs).  Recent efforts to survey the asteroid belt for those objects that may pose a future hazard has resulted in a very well characterized size distribution.  As the size of asteroids decreases, the number of asteroids increases.  In other words, there are just a few very large asteroids (Ceres, Vesta), and thousands upon thousands of the very small (under 100 m).  

The size distribution of asteroids surveyed by the Sloan Telescope.  The population number is normalized the population of 10 km objects.  The asteroid population is a continuum, as is the population of objects in the Solar System.  (Image credit:  Unknown).

If the origin of the classical planets and their moons, the asteroids, the KBOs, and the uncountable dust grains were different, these different origins might serve as a means by which to establish a scientific categorization.   However, the origin of all these objects is the same.  All the objects are the result of countless collisions and gravitational collapse of a protoplanetary disk.   It is the collision and accretion that results in the nearly log-normal size continuum of objects in the Solar System.  Asteroids are just the bits of rubble left over that were not accreted by larger objects.   The asteroids themselves may very well be conglomerations of smaller bits of dust and rock rather than the more solid monolithic structures of the science fiction genera.  KBOs are the bits of rubble in the Outer Solar System that were not accreted.

So here we are today.  We inherited the term planet, originally used to describe the wandering nature of objects against the more predictable background stars.  Millennia ago, we were aware of only a handful of these objects.  In time we found that the wanderers were not only distinct from stars in their journey across the sky, but that they were not stars at all; they really were in a class by themselves.  The idea of planet made sense.  Then, we found that there were more than just a handful of planets.  First there were dozens, then hundreds, then thousands, then tens of thousands!  It still makes sense to distinguish these objects from stars, as they are quite clearly different (for example, there is no nuclear fusion and they are not at the center of the Solar System). 

What does not make scientific sense is to further scientifically categorize the range of solar system objects.  Doing so inherently requires defining arbitrary defining lines in a size continuum.  While such dividing lines can certainly be legislated by such bodies as the International Astronomical Union (IAU), they have no meaningful basis, and such an exercise merely brings to light the hubris of man trying to sort nature into boxes and bins.

In time, the concept of a planet will find its way to the dust bins of astronomical rubbish, atop celestial spheres and the geocentric model of the Solar System.  Astronomers of the future will recognize the continuum of objects in our Solar System and in extra solar systems, too.  Any distinction between objects will be one of convenience rather than of scientific purpose, just as asteroids were once distinguished from planets solely for convenience.  Historians of science will study the transition of the Classical Planetary Model to the Modern Solar System Continuum Model, and children of the future will chuckle at the silly argument made over whether Pluto is a planet, just as we all chuckle over the argument of a circular or rectangular flat Earth.

The concept of a planet is dead.