Re-interpreting “coherence” in light of Non-Interaction of Waves, or the NIW-Principle Chandrasekhar Roychoudhuri a,b a Physics Department, University of Connecticut & b Femto Macro Continuum, Storrs, CT, USA ABSTRACT The autocorrelation, or the Wiener-Khintchine, theorem plays a pivotal role in optical coherence theory. Its proof derives from the time-frequency Fourier theorem. The derivation requires either dropping the cross-products (interference terms) between the different filed amplitudes corresponding to different frequencies, or taking time integration over the entire duration of the signal. The physical interpretation of these mathematical steps implies either (i) non-interference (non- interaction) between different frequencies, or (ii) the registered data is valid for interpretation when the detector is set for long time integration. We have already proposed the generic principle of Non-Interaction Waves (NIW), or absence of interference between light beams. The hypothesis of non-interaction between different frequencies was used by Michelson to frame the theory behind his Fourier Transform Spectroscopy, which is correct only when the detector possesses a long integrating time constant like a human eye, a photographic plate, or a photo detector circuit with a long LCR time constant. A fast detector gives heterodyne signal. So, the correlation factor derived by the prevailing coherence theory, and measured through fringe visibility, is essentially the quantum property of the detecting molecules compounded by the rest of the follow-on instrumentation. Low visibility fringes (low correlation factor) does not reflect intrinsic property of light alone; it is a light-matter joint response characteristics. So, we re-define coherence by directly referring to the key characteristics of light beams being analyzed as: (i) spectral correlation (presence of multi frequency), (ii) temporal correlation (time varying amplitude of light), (iii) spatial correlation (independent multi-point source), and (iv) complex correlation (mixture of previous characteristics). Keywords: Coherence; Optical correlation; NIW-principle; Spectral correlation; Temporal correlation; Spatial correlation; Complex correlation. 1. INTRODUCTION Detectors determine what we measure. We see light only through the eyes of the detectors! A detector can neither gather all the information about the stimulant it is detecting, nor can it deliver that limited information with 100% fidelity to our recorders, since our instruments are always band-limited. This is a Perpetual Information Challenge (PIC), a natural constraint that we must learn to overcome by iteratively improving all of our working theories as our knowledge advances and technology improves for more complex and precise measurements. The approach would require focusing on the interaction processes and information gathering processes and iteratively keep on improving our current and future working theories. 1.1. Detectors determine the superposition effects - developing the rationale further Our starting platform is the semi-classical model for light-matter interaction processes: space and time finite wave packet interacts with quantized atoms [1,2]. Propagation characteristics of light is modeled quite successfully from the most macro to nano distances, from predicting coherence properties of the Sun & star lights to accurately modeling nano photonics devices, using Huygens-Fresnel diffraction integral and Maxwell’s wave equation. None of these modeling require propagation of indivisible photons. Such attempts only introduces non-causal hypotheses. 1.1.1. We are underscoring the need for interaction process mapping epistemology (IPM-E): All measured data are results of physical transformations experienced by interactants through energy exchange due to physical interaction process guided by some allowed force of interaction between them. The prevailing measurable data modeling epistemology (MDM-E) is not sufficient to advance physics, although it is a critically necessary step [3,4]. The Nature of Light: What are Photons? IV, edited by Chandrasekhar Roychoudhuri, Andrei Yu. Khrennikov, Al F. Kracklauer, Proc. of SPIE Vol. 8121, 81211A · © 2011 SPIE CCC code: 0277-786X/11/$18 · doi: 10.1117/12.895183 Proc. of SPIE Vol. 8121 81211A-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 03/16/2015 Terms of Use: http://spiedl.org/terms