Molecular explanation of the phenomenon known as ‘water memory’: Search into the mysteries of homeopathic potentization inevitably leads us to the study of the wonderful physical and chemical properties of water and alcohol, which constitute the medium used to prepare the ultra dilute preparations. Water is the the most common and abundant mineral on earth. We may begin our discussion by looking into the wealth of information already collected by modern material sciences on this subject. ‘Molecular memory of water’ is a rarely understood phenomenon, and is a subject of much controversies and speculations in the world of science. Even now, scientists differ much in their opinion regarding this phenomenon. Final outcome of these controversies will have great concern and significance in the realm of homoeopathy. Let us examine some details of the nature and essence of this controversial phenomenon. Until recently, we knew precious little about various miraculous properties of water, though we find it in plenty around us, and utilize freely in our everyday life. Even the highly equipped scientific community has begun to turn its serious attention to the minute level study of water only in recent times. The secrets being revealed in these studies are really amazing, and may help us in solving the mysteries haunting homeopathic potentization. Around seventy percent of the surface of earth is covered with water. 45-70% of human body mass consist of water. This ratio slightly changes with age, and it may be said that human body becomes more and more dry with aging. 30-40 % of water contained in our body is seen in the intra-cellular fluid,12-16% as extra-cellular , and 5 % in blood plasma. 2% of water is in lymph, and 1-3% in different body cavities. This wide spread presence of water in the living body indicates the paramount importance of its role in various biological processes. About 2 litters of water enters our body from outside, along with food every day. A small quantity of water is produced in the body itself as a by-product of metabolism. As far as we know, life cannot exist without water. It is considered that the phenomenon of life originated on this earth only because of the presence of water. All the biochemical processes in the organism take place with the involvement of water. In the absence of water, essential biological molecules such as proteins and DNA undergo structural changes, and become inactivated. Water is the essential condition of existence of life. Liquid water has importance as a solvent, a solute, a reactant and a biomolecule, structuring proteins, nucleic acids and cells and controlling our consciousness. The complex three dimensional formations of protein molecules, which are much important in their biological functioning, is due to the hydration properties of water. Why this simple hydrogen oxide(H2O), which is formed by the union of two hydrogen atoms and a single oxygen atom happen to play such a crucial role in the origin and existence of life? What are the factors that make water distinct from other similar chemical compounds such as hydrogen sulphide? The answers to this question lies in the wonderful physico–chemical properties of water, arising from its peculiar super-molecular structure. Water is a solvent with higher polarity than similar liquids. H–O–H have bond angle of 105 degrees. That means, water molecule is a dipole. Because of this peculiarity, water molecules can exist like a super-molecular network by forming hydrogen bonds between themselves. A minimum number of five water molecules will be contained in this network. Such five-molecule formations are called ‘pentamers’. Most of the wonderful properties of water arise from this capacity of peculiar hydrogen bonding and supra-molecular formations. Water molecules are normally considered to be in a state of random movement in their liquid form. But recent studies have shown that water molecules move not as individual molecules, but as supramolecular clusters. We all know that water exists as ice crystals in its solid form. But it has been recently observed that in its short range structure, water exist as nanocrystals even in its liquid form. We know, water formed by melting of ice behaves exactly as if in a state of liquid crystals. The lattice structure which is formed through hydration bonds is responsible for this phenomenon. A lot of research work is recently undertaken all over the world regarding the phenomenon of peculiar supra-molecular formations of water. The uncommon physico– chemical properties of water are the result of this poly-molecular structure at supra-molecular level. Water becomes an essential material for the existence of life on earth, by its strange properties such as high polarity, anomalous expansion, anomalous boiling and melting points, high viscosity, surface tension, thermal storage capacity, high specific heat, hydration properties etc. Water molecules(H2O) are symmetric (point group C2ν), with two mirror planes of symmetry and a 2-fold rotation axis. The hydrogen atoms in this molecule may possess parallel or anti-parallel nuclear spin. The water molecule consists of two light hydrogen atoms(H) and a relatively heavy oxygen atom(O). The approximately 16-fold difference in mass between hydrogen and oxygen gives ease of rotation, and the significant relative movements of the hydrogen nuclei, which are in constant and significant relative movement. Although not often perceived as such, water is a very reactive molecule at a high concentration. This reactivity of water molecules, however, is greatly moderated at ambient temperatures due to the extensive hydrogen bonding between them. Water molecule possess a strongly nucleophilic oxygen atom that enables it for many of its biological functions, as well as ionizing to produce reactive hydrogen and hydroxide ions. Reduction of the hydrogen bonding at high temperatures, or due to electromagnetic fields, results in greater reactivity of the water molecules. ‘Magnetized’ water will be more reactive, with strange properties. Much experienced phenomenon of loss of medicinal properties of homeopathic potencies, when subjected to influence of magnetic fields and electrical fields could be well explained now. This also gives an indication to the role of hydrogen bonding in potentization. As liquid water is so common-place in our everyday lives, it is often regarded as a ‘normal’ liquid. In reality, water is most ‘abnormal’ as a liquid, behaving as a quite different material at low temperatures compared to that when it is hot. It has often been stated that life depends on these anomalous properties of water. In particular, the high cohesion between molecules gives it a high freezing and melting point, such that we and our planet exist bathed in liquid water even at high ambient temperatures. In the absence of hydrogen bonding, all water on earth would have vaporized even at very low temperatures. The large heat capacity, high thermal conductivity and high water content in organisms contribute to thermal regulation and prevent local temperature fluctuations, thus allowing us to more easily control our body temperature. The high latent heat of evaporation gives resistance to dehydration and considerable evaporative cooling. Water is an excellent solvent due to its polarity, high dielectric constant and small size, particularly for polar and ionic compounds and salts. It has unique hydration properties towards biological macromolecules (particularly proteins and nucleic acids) that determine their three-dimensional structures, and hence their functions, in solution. This hydration forms gels that can reversibly undergo the gel-sol phase transitions that underlie many cellular mechanisms. Water ionize and allows easy proton exchange between molecules, so contributing to the richness of the ionic interactions in biology. Essentially, ‘hydrogen bonding’ is a special type of dipole force. It is a force of attraction formed between partially charged atoms being part of different molecules. The reason for this bonding is the partial positive charge attained by hydrogen. Hydrogen is capable of establishing similar bonds with the atoms of nitrogen, fluorine and oxygen. That is to say that the basis of hydrogen bonding is the attraction between one hydrogen atom which is part of a molecule which is attached to oxygen or nitrogen and oxygen or nitrogen which remains part of another molecule. This force is less powerful than the covalent bonds which keeps the atoms inside molecule bound together. But it may be strange that these less powerful bonds are responsible for the wonderful physico–chemical properties and biological relevance of water. In the ordinary liquid state, in spite of 80% of the electrons being engaged in bonding, the three atoms in water do not stay together, as the hydrogen atoms are constantly exchanged between water molecules due to protonation/deprotonation processes. Both acids and bases catalyze this exchange and even when at its slowest(at pH 7), the average time for the atoms in an H2O molecule to stay together is only about a millisecond. As this brief period is, however, much longer than the timescales encountered during investigations into water’s hydrogen bonding or hydration properties, water is usually treated as a permanent structure. But when water exist in its crystalline form, hydrogen atoms become more stable. The presence of ethyl alcohol in water is considered as a factor reducing the rate of protonation/deprotonation processes, thereby enhancing the stability of hydration shells. Importance of using water-ethanol mixture for homeopathic potentization is self-explained here. It has been already stated that hydrogen bond strength can also be affected by electromagnetic and magnetic effects. Any factors, such as polarization, that reduces the hydrogen bond length, is expected to increase its covalency. There is still some dispute over the size of this co-valency, however any co-valency will increase the network stability relative to purely electrostatic effects. As hydrogen bond strength depends almost linearly on its length (shorter length giving stronger hydrogen bonding), it also depends almost linearly (outside extreme values) on the temperature and pressure . It has to be verified whether the violent succussion and rotatory motion done during potentization procedure any how plays a role in polarization of molecules, thereby reducing the hydrogen bond lengths, and increasing the stability of hydration shells formed. Hydrogen bonded chains (that is, O-H····O-H····O) are cooperative; the breakage of the first bond is the hardest, then the next one is weakened, and so on (see the cyclic water pentamer). Thus unzipping may occur with complex macromolecules held together by hydrogen bonding, for example, nucleic acids. Such co-operativity is a fundamental property of liquid water where hydrogen bonds are up to 250% stronger than the single hydrogen bond in the dimer . A strong base at the end of a chain may strengthen the bonding further. At this stage we have to understand a few facts about Ethyl Alcohol(CH3- CH2 – OH ). The molecules of alcohol also have the dipole structure as water molecules. It is possible for them to establish mutual connection through hydrogen bonding. The molecular weight of alcohol molecule is 46. The molecular weight of water(H2O) is 18. That means that the number of water molecules contained in 18 gram of water and the number of alcohol molecules contained in 46 gram of ethyl alcohol are equal. When alcohol and water are thoroughly mixed alcohol molecules forms a network with water molecules through hydrogen bonds, The mobility of water molecules is restricted by the bonds established with alcohol molecules. Hence, hydration shells formed in alcohol–water mixture are comparatively more stable. The count of alcohol molecules and the count of water molecules contained in their mixture in 73:27 ratio will be equal. (73% w/w. alcohol and 27% w/w water) This mixture is known as (40 power spirit). Medium used for homoeopathic potentization is a mixture containing 87% w/w of alcohol and 13% w/w of water. In this ratio, the number of alcohol molecules will be about more than that of of water molecules. Rectified spirit is an azeotrope containing 95% alcohol and 5%water. Such a ratio will be very suitable for the production of stable hydration shells. More over, the presence of ethyl alcohol in water is considered as a factor reducing the rate of protonation/deprotonation processes, thereby enhancing the stability of hydration shells. This may further explain the importance of water-ethyl alcohol mixture being used as the medium of homoeopathic potentization. We know that water is a good solvent. Let us see what happens when foreign molecules are made to dissolve in water. If a foreign molecule, ion, or colloidal particle happens to enter the matrix of 3-dimensional dynamic network of water molecules, they are entrapped inside this network. Water molecules arrange themselves around the intruder or ‘guest’ in a peculiar way by the formation hydrogen bonds. These formations of water molecules around the ‘guest’ molecules are known as hydration shells. These hydration shells exist in a dynamic state, and are more or less unstable. The foreign molecules dissolved in water exist in a state of being entrapped inside these hydration shells as ‘guests’. This phenomenon can be seen both in ionic solutions and colloidal solutions. Obviously, hydration shells assume an internal spacial arrangement exactly fitting to the 3-dimensional spacial configuration of the foreign molecule entrapped in them. If we could devise some technique to remove the entrapped ‘guest’ molecules from these hydration shells, without disturbing the hydrogen bonds between the constituent water molecules, these hydration shells can still retain the molecular memory of the molecular configurations of the removed ‘guest’ molecules. This rarely studied phenomenon is known as ‘molecular memory of water’. Actual mechanism and forces underlying this phenomenon has to be investigated minutely by physical scientists. Minute changes occurring in the electron clouds of atoms of water molecules during the formation of hydration shells may be one factor responsible for this phenomenon. It has been well proven that these hydration shells later show a peculiar capability to differentially recognize the original ‘guest’ molecules which were responsible for their formation. This may be due to the existence of some imprinted memory of those ‘guest’ molecules retained in the hydration shells. This imprinting of memory may be compared to formation of finger prints. As in the case of finger prints, configuration of these molecular imprints also will be a complementary negative of ‘guest’ molecules. These empty hydration shells, or supra-molecular formations of water subjected to molecular imprinting, may be called ‘hydrosomes’, which means, minute ‘nano-cavities of water’. Homeopathic process of potentization is essentially a crude method of preparing hydrosomes, prepared by using various drug molecules as ‘guests’. It should be specifically noted that the medium used for homeopathic potentisation is not pure water, but it is mixed with ethyl alcohol in a particular ratio. It may be inferred that the presence of comparatively heavy ethyl alcohol molecules in this mixture may be contributing to stabilization of ‘hydrosomes’, preventing their easy dissociation. The convergent forces of rotational movements to which the mixture is subjected as part of potentization, may also be a contributing factor in stabilizing the empty hydration shells by polarization and subsequent reduction of hydrogen bond lengths.. This peculiar configuration of hydrosomes are destroyed only when their energy level of water molecules are disturbed by the effect of heat, electricity, magnetism and other electro magnetic radiations. As stated earlier the hydration shells formed in pure water are comparatively unstable. Here lies the importance of the fact that homeopathic potencies are made using alcohol- water mixture.