What is the Difference between Macroscopic and Microscopic Physics?

Multiscale modeling with simple ordered microscale (atom) and ordered macroscale (car) connected by complex intermediate scales.

The standard view is that classical physics is useful to describe the macroscopic world, like the flow of air around an airplane or the formation of a galaxy,  while the microscopic world of atoms and molecules requires a fundamentally different form of physics named quantum mechanics.

The standard view is thus that the world is divided into a macroscopic world and a microscopic world supposedly governed by different physics. The standard view is that we as human beings with experience from the macroscopic world cannot fathom the microscopic world because it is so fundamentally different from the macroscopic world.

But is it really reasonable from a scientific point of view to divide the world this way? What is the dividing line? How does the microscopic world interact with the macroscopic world?
Is it possible to tell if a mathematical model in its typical form of a differential equation describes microscopic or macroscopic physics?

None of these questions has a good answer and it is then natural to seek the origin of the idea that microscopics is so different from macroscopics. The standard wisdom says that microscopics is described by quantum mechanics and macroscopics by classical mechanics and quantum mechanics is fundamentally different from classical mechanics and therefore macroscopics is fundamentally different from microscopics.

The standard wisdom according to the Copenhagen interpretation of quantum mechanics is that the microscopic world is a strange world without causality and predictability functioning like a microscopic game of roulette. This strange idea comes from the insistence to describe microscopics by a multi-dimensional linear Schrödinger equation, which because of its many dimensions can only be given a probabilistic interpretation and not a physical realistic interpretation.

The multi-d linear Schrödinger equation is an ad hoc model which is not derived from basic principles and thus is accepted as a true mystery beyond comprehension of human minds and as such necessarily a correct description of microscopics.

But suppose, we do not take the incomprehensible (and uncomputable) linear multi-d Schrödinger equation as description of microscopics, because this lacks rationale. Suppose we seek instead a description in the form of field equations in three space dimensions plus time, in the form of Hartree models as non-linear coupled systems of one-particle Schrödinger equations, which have the same principal form as macroscopic continuum models.

Then there will be no fundamental difference between microscopics and macroscopics and all the problems arising from postulating such a difference will disappear. This must be a good case for Ockham's razor.

Note that claiming that microscopics functions like a game of roulette is contradictory, because a game of roulette requires microscopics, which leads to an infinite regression of microscopics upon microscopics. When I present this argument, which makes perfect sense to a classical physicist, in a discussion with a modern physicist, I get no response as if this argument is beyond what is allowed in modern physics. Is this reasonable?    

Global Climate = Thermodynamics + Radiation

A basic model of global climate may take the form of the Earth E as a blackbody surrounded by 

an atmosphere A as another blackbody. Observation gives the following data (cf. Atmosphere as Refrigerator):

• Temperature of E = T_E = + 15 C
• Temperature of A = T_A = - 18 C
• Radiative forcing of E by insolation = 240 W/m2
• Radiation from A to outer space = 240 W/m2.  

We assume that the forcing 240 W/m2 is given, which by Stefan Boltzmann sets T_A = -18 C in accordance with observation. 

We want to find out what sets T_E to + 15 C.

Heat is transferred from E to A by thermodynamics (convection and latent heat) and radiation.

According to Stefan-Boltzmann a temperature drop 0f 33 C from E to A corresponds to roughly

120 W/m2. The heat transfer from E to A is thus roughly divided equally:

• thermodynamics = 120 W/m2
• radiation = 120 W/m2. 
  

In this model A is a blackbody, that is A is assumed to be fully opaque to infrared radiation from E. We cannot make A more black but possibly less black. 

If A is made fully transparent to radiation, or if A is simply removed, then the Earth could directly emit whatever is absorbed at T_E = -18 C.  The presence of an atmosphere absorbing outgoing radiation from the Earth combined with thermodynamics, thus increases T_E from -18 C to + 15 C. This is a "greenhouse effect" of combined thermodynamics-radiation, which has nothing to do with (non-existing) "backradiation"

If A is made fully opaque to also incoming radiation, then A and E both would have a temperature of T_E = T_A = - 18 C (without thermodynamics).

We know turn to the real case somewhere in between a fully transparent and fully opaque 

atmosphere, in which case T_E = + 15 C according to observation, as a result of 

thermodynamics and radiation.

Suppose now that from this present situation, the property of the atmosphere is changed a little (say 1%) by doubling the concentration of the trace gas CO2. Climate sensitivity S is defined as the corresponding change in T_E. The basic question in AGW is the size of S.

If A is already a blackbody, then S = 0.

If A is not black then the present equal partition 120/120 between thermodynamics and radiation will have to shift in the direction of thermodynamics. But it is not clear if that will

cause warming; maybe the thermodynamics simply gets a little bit more vigorous without 

change of the temperature profile. Like a boiling pot on the stove under increased heating.

In any case, it seems that the thermodynamics determines the lapse rate and thus the temperature profile anchored at -18 C at the (top of the) atmosphere. Radiation operates on this profile, passively as it seems. In order to determine climate sensitivity S, it is thus necessary to study the coupled thermodynamics-radiation system. 

No conclusion derived from radiation only, can be scientifically meaningful. In particular not the basic axiom of climate alarmism that S = 1.2 C as a start to feed-back to inflate. 

If anything, it seems more reasonable to set as a start S = 0, and then feed-back has nothing to eat.

 

In the above model there is no need to introduce the basic concepts of IPCC's CO2 alarmism: "backradiation", "radiative forcing" and "effective radiation into space from a higher altitude at a lower temperature". Using Ockham's razor we find that these concepts belong to fiction and not science.

Concerning radiation, see Computational Blackbody Radiation. For thermodynamics, see Computational Thermodynamics.

Cutoff of Backradiation by Ockham's Razor

The discussion in previous posts on the non-physical nature of backradiation directly connects to the physics of blackbody radiation studied in Computational Blackbody Radiation in a mathematical model of the principal form (in stationary state)

• R = LR + HR 

where R is incoming absorbed radiation by a blackbody B at temperature TB, where the radiation originates from a body A at temperature TA bigger than TB and thus contains  both low and high frequencies, LR is the low-frequency infrared part of R after cut-off of the high-frequency part HR with the level of cut-off defined by TB.

We thus assume that the blackbody B is heated by A, because cut-off requires something substantial to be cut-off.  A thief seeks a richer to rob, not a poorer.

We know that the spectrum of R carries its emission temperature, assuming it follows Planck's Law, and thus B at absorption can check if there is some radiation to absorb and process (without having access to the temperature of A, only to the radiation from A about to be absorbed).

We thus consider a body B which is absorbing radiation R of a temperature bigger than its own.

The model describes how the body B handles this situation by cutting off the high frequency part HR (grinding it into low frequency heat) and ends up with a low frequency part LR which is prepared for emission. 

We thus focus on the absorption process with the cut-off and we can leave the emission process out of the discussion. The advantage is that that we do not have to deal with a two-way communication between A and B,  with a hypothetical backradiation from B at low temperature to A at high temperature.

By focussing on incoming instead of outgoing radiation, we focus on what is essential, and leave out what is inessential. We thus make use of Ockham's razor as the basic principle of science.  

To sum up: 

• It is interesting to study the absorption by the Earth of radiation from the Sun, but not interesting to study the absorption by the Sun of radiation from the Earth. 
• It is interesting to study the absorption by the atmosphere of radiation from the Earth, but not interesting to study fictional backradiation from the atmosphere to the Earth.

Note that Ben Herman and Roger Pielke in the post The Greenhouse Effect of today, start off:

• During the past several months there have been various, unpublished studies circulating around the blogosphere and elsewhere claiming that the “greenhouse effect” cannot warm the Earth’s atmosphere. 
  

It is possible that my blog is involved. Herman and Pielke now seek to correct what is circulating by explaining the arguments that have been put forth and why they are incorrect: 

• When absorbing gases are added to the atmosphere, more of emitted radiation from the ground is absorbed by the atmosphere. This results in increased downward radiation toward the surface, so that the rate of escape of IR radiation to space is decreased, i.e., the rate of infrared cooling is decreased. This results in warming of the lower atmosphere and thus the second law is not violated. Thus, the warming is a result of decreased cooling rates. 
  

We here meet exactly what Ockham's razor cut off, namely "downward radiation". What is the truth? Fiction or non-fiction? Is my argument incorrect?

Note that Herman and Pielke use quotation marks around the greenhouse effect and also speak about the 

• so-called "greenhouse theory"
  

with their own quotation marks. But if you put quotation marks around theory, doesn't that indicate that it is not a theory, but only a "theory". What is then the  status of "theory" in science? Is it a "theory" because it is only folklore and not described in physics literature?

Of course the presence of an atmosphere can affect the temperature on Earth, in many ways: Is this the meaning of the "greenhouse theory" and "greenhouse effect"? Maybe it would then be better to call it "atmosphere effect", but it remains to tell what this effect is.