Delivered by Publishing Technology to: Isabelle Legault IP: 132.204.170.23 On: Mon, 04 May 2015 18:25:14 Copyright: American Scientific Publishers Copyright © 2015 American Scientific Publishers All rights reserved Printed in the United States of America Article Advanced Science, Engineering and Medicine Vol. 7, 62–75, 2015 www.aspbs.com/asem Physical Analogies in Biology: From Photons, Phonons, Bloch Waves to Non Linear Oscillators J. E. Lugo 1 , R. Doti 1 , R. Agarwal 2 , K. Ray 3 ∗ , and J. Faubert 1 1 Visual Perception and Psychophysics Laboratory, Universite de Montreal, H3T 1P1, Canada 2 Malviya National Institute of Technology, Rajasthan 302017, India 3 Amity School of Engineering and Technology, Amity University, Rajasthan 303001, India The existence of physical analogies in biology is more evident nowadays than it had been in the past. Efforts of physicists trying to understand biological systems are increasing rapidly. For instance, the field of photonics can explain the color of many insects. Here we discuss several interesting physical concepts that could help us better understand many biological systems ranging from microtubules, muscles, dendrites and human perception. Keywords: Laser, Microtubules, Phonons, Muscles, Bloch Waves, Neuronic Crystals, Non Linear Oscillators, Fulcrum Principle. 1. INTRODUCTION In the past, there were two antagonist schools or methods of thinking for understanding biological systems. On the one hand, one school held that all biological phenomena could be explained in terms of physical properties of unor- ganized matter (materialism). On the second hand, others were inclined to believe that the activities of living mat- ter presented relationships not shown in the unorganized world (vitalism). Currently, there is a different way of thinking in regards to biological systems that is known as emergentism. Emergent processes are considered as those in which the properties of a system could not be fully understood in terms of the properties of the components. 1 2 This could be the consequence of the properties of the constituents not being fully comprehended, or the rela- tions between the individual components are related to the dynamics of the system. For instance in evolution, if phys- ical or mathematical models or principles are to serve any useful purpose in showing what are the underlying mech- anisms of the evolutionary process then the specific orga- nization rules or speciety of the biological world must be recognize. 3 In physics the importance of organization in atomic and molecular systems is known. Most of the basic chemi- cal elements can be classified by the spatial organization of the crystal they can form. This spatial organization is known as a Bravais lattice and there exists only 14 possible ∗ Author to whom correspondence should be addressed. arrays in a three-dimensional space. The atomic or molec- ular crystals are made up of one or more atoms (known as the basis) repeated at each lattice point. Therefore, the crystal appears the same when observed from any other tantamount lattice point, namely those separated by the translation of a basic three-dimensional cell known as the unit cell. In these crystal elements the periodic poten- tial due to the atomic basis affects the electron motion by defining the allowed and forbidden electronic energy bands. Besides natural crystalline elements, we also found man-made crystalline-like systems that mimic the same physical properties of their natural counterparts: Phononic crystals, where the motion of phonons is affected by the periodical variation of the mass and elasticity of each of their components, and, photonic crystals, where the motion of photons is affected by the periodical variation of the dielectric constant of each of their components. Moreover, there are also examples of natural photonic crystals such as the opal mineral, 4 and a Brazilian beetle. 5 Another special organization physical concept occurs in the time domain with the phenomenon known as “res- onance.” A resonance is the inclination of a system to oscillate in time at some specific frequency with high amplitude. It may be more than one resonance frequency and at these frequencies, small periodic or stochastic driving forces can induce very large amplitude oscilla- tions, because the system can store and transfer kinetic and potential energy as in the case of a pendulum. Nonetheless, there might be some energy losses from cycle to cycle, known as damping. Resonance phenomena 62 Adv. Sci. Eng. Med. 2015, Vol. 7, No. 1 2164-6627/2015/7/062/014 doi:10.1166/asem.2015.1647