fredag 21 oktober 2011

The Fiction of Heating by DLR and CMB

The Holmdal Horn Antenna used by Penzias and Wilson to first discover CMB.

This is a continuation of the post Picture of CMB from Resonance, Not Radiative Heating.

Cosmic Microwave Background Radiation (CMB) is supposed to be a "faint glow" at 3 K of thermal radiation filling the empty space of the Universe as relic of Big Bang and Downwelling Longwave Radiation (DLR) is similarly supposed to be a "glow" of the atmosphere with the effect of heating the Earth surface.

DLR is supposed to be very substantial, of the same size as the insolation, about 300 W/m2, while CMB is indeed very faint about 100 million times smaller, in accordance with Stefan-Boltzmann's radiation law (SB) stating that radiance scales like $T^4$ with $T$ temperature in Kelvin K and the temperature of the atmosphere is about $100\times 3$ K.

Measurements of CMB by the COBE gave the Nobel Prize in Physics in 2006 to Georg Smooth and John Mather for discovering CMB. Similarly, measurements of DLR are presented as evidence of DLR supporting CO2 alarmism.

The existence of both CMB and DLR is thus manifested by certain instrument readings and to understand the nature of CMB and DLR, we have to ask what in fact the instrument or detector, is recording.

The detector of CMB is a radio-telescope, which like a radio tuner tunes in different resonance frequencies of an antenna which produces an electrical signal, which is amplified into a recording over frequency or a spectrum.

The recorded spectrum is matched with a black-body spectrum according to Planck's law,
where the peak of the recorded spectrum determines the temperature (3 K) from which a radiance can be computed by Planck's law. The recorded spectrum is thus translated by using Planck's law into a radiance measured in W/m2, which is perceived as a "faint glow".

Does this mean that the faint glow of CMB is heating the Earth? There are two answers, depending on which form of Stefan-Boltzmann's radiation law (sum over frequencies of Planck's law) we are willing to use: False-SB or True-SB.

False-SB says that the faint glow of CMB heats the Earth with $\sigma T_b^4$ W/m2 where $\sigma$ is Stefan-Boltzmann's constant and $T_b$ is the temperature computed from the spectrum. False-SB states that there is a flow of heat energy from empty space to the Earth of size $\sigma T_b^4$ (with $T_b = 3$ K).

True-SB states that there is a transfer of heat energy from the Earth(+atmosphere) to space of size $\sigma (T^4 - T_b^4)$ where $T > T_b$ is the temperature of the Earth, but no transfer from space to the Earth.

False-SB is false in the sense that it lacks description/justification in physics literature.
True-SB has massive theoretical and experimental support.

We sum up our experience of CMB:
  1. CMB is measured by radio resonance into a spectrum without physical scale because of signal amplification.
  2. The recorded spectrum is matched with Planck's law to give a temperature $T_b$.
  3. False-SB is used to compute a radiance $R =\sigma T_b^4$ as a faint glow of CMB heating the Earth.
A similar procedure is used to record a spectrum of DLR, and from the spectrum compute
DLR as heat transfer/radiance from the atmosphere to the Earth.

We see that in both cases, a spectrum is recorded, and from the spectrum a radiance is computed by a False-SB. We understand that an instrument recording of CMB/DLR is one thing, and radiance of CMB/DLR is something different: It is not recorded but computed using a False-SB without physical justification.

We conclude that the interpretation of CMB/DLR as radiance expressed in W/m2, lacks rationale. CMB should not be described as a "faint glow". DLR should not be viewed as heating the Earth surface.

2 kommentarer:

  1. The CMB is a very very close approximation of a black body. Therefore it is well described by the Planck function. Radiation from the atmosphere is not a close approximation of a black body. Therefore nobody uses the Planck function or the Stefan-Boltzmann law to do anything with it.

    Still, nice to see you changing your position. Where formerly you claimed on numerous occasions that radiation from the atmosphere was "fiction" or a "myth", now you acknowledge its existence but it's the heating from it that's now "fiction".

  2. I do not say that there is radiation (of heat) from CMB. What I say is that a radio antenna may detect electromagnetic waves by resonsnce and by amplification make the signal appear in front of the eyes of a human being as a spectrum plot. That is real. To interpret the plot as radiation (of heat) by SB is pure fiction. It is misleading to say that CMB is "faint glow" like a weak furnace glow. CMB does not transfer heat energy to the Earth and neither DLR.