A loss of microwave absorption in the ESR experiment could be a result of a reduction in radical concentration through chemical reaction, a heat-induced g-shift, or a change in the externally perceived frequency or magnetic field by the unpaired electron within the radical, such that the conditions for microwave absorption (resonance) are no longer met. In this experiment, the gradual increase of a laser-irradiation-induced stable melanin radical was being monitored over time and there is no indication of any loss in the radical signal through chemical reaction in the field scans. It is known that heat can induce changes in the spectrum of radicals, for example, in graphite [11]. Heat is released during the experiment in the hair sample which melts but does not combust. No combustion is possibly because the air supply in the sealed capillary is limited. Thus, during an experiment where the hair is lasered 36 times, the temperature of the hair in the capillary tube will increase. Despite this increase, there is no shift in the peak resonance field of the laser-induced radical or variation in experimental frequency, thus the g value is invariant. This is consistent with published data to show that melanin spin concentrations are invariant with temperature in the solid and frozen state, although they do vary in hydrated solution [7]. In the ESR experiment, microwaves are generated by a Klystron microwave generator which is separate from the ESR cavity and not subject to heating or relative motion. The frequency of the waves entering the ESR cavity therefore remains unchanged. The cavity space is tuned by making small adjustments in the cavity volume using the iris until the microwaves form a standing wave in the cavity for the chosen microwave power. It is possible that cavity heating affects the cavity volume, and therefore tuning of the standing wave. In the field-scan experiments the cavity was tuned with the hair sample inside, and the scan of the intrinsic melanin radical obtained. The hair was lasered and a spectrum recorded immediately over 5-40 seconds. Tiny adjustments with the iris were made, after the irradiation, to again maximise the tuning or the standing wave in the cavity before irradiating the sample further. The laser pulse was a collimated beam of radiation of area 1 cm2 which passed through the cavity grid, and was directed onto the hair sample held in place by a silica capillary and positioned such that the hair was central in the laser beam. The collimated beam was horizontal because the probe was positioned horizontally. The radiation absorbed by the melanin in hair is estimated to be 6 -10 J. This was after the beam had first passed through the cavity grid, where some scattering losses could occur, and then through the silica sample holder walls and the capillary walls. The outer keratin layer of the hair being a protein and non-pigmented will absorb minimally at this wavelength [13]. Of 17 J in the laser pulse, 6 -10 J is assumed to be absorbed by the melanin pigment in the hair. An estimated 50% of the energy is absorbed and the remainder would hit the back wall of the cavity, being either absorbed in the wall or scattered and reflected within the gold-plated cavity. The gold lining of the cavity would probably scatter more radiation, rather than absorb it and generating heat. Because the sample was lasered successively, any cavity heating effects on the tuning of the microwaves due to cavity expansion over the course of the experiment might be expected to increase linearly with time, not only through the radiation scattered within the cavity but also due to the hair sample temperature increasing. A sudden change in the microwave standing wave due to heat, however, ought to result in a complete loss of absorption during the time scan, rather than the reversible and incomplete signal drop observed after each laser pulse.
In the absence of any radical-radical recombination reaction or temperature induced g-shift or change in tuning of the standing wave in the cavity, it remains to consider the possibility that the magnetic field changes in the spectrometer to a new magnetic field Bnew (during the period of ‘off resonance’). Here only a smaller proportion of electron-spins undergo a spin-spin transition of unpaired electron spin from lower to upper spin states. It is accepted that the velocity of light decreases in a dense medium compared with its speed in vacuo and also that a photon has particle and wave properties. Photon frequency is a fixed property of waves, which cannot be measured but only calculated [12] and does not change when a wave passes from a vacuum into a more-dense medium. Photon velocity and wavelength are variable, and according to the classical wave equation (wave velocity = fλ) wavelength λ must decrease as a wave passes into a more-dense medium proportionately as the velocity of light decreases. As a photon slows down on entering a more-dense medium, it will effectively “bunch” together in space, ie. the oscillations per metre increasing, such that the number of waves or oscillations per second remain constant at constant frequency. Thus, it will appear more particle-like as it enters a dense medium, a constant number of wavelengths covering a smaller distance in unit time. As it speeds up in a less dense medium, it will lengthen, since the same number of wavelengths will occupy a greater distance in space. Laser photons in this experiment first enter the keratin of the solid hair matrix, within which the melanin-containing melanosomes are embedded. Melanin is a brown/black light absorbing pigment, which absorbs widely across the UV/visible and infra-red radiation spectrum [4, 5]. Whilst melanin absorbs radiation at 694 nm, the keratin protein has minimal absorption at this wavelength [12]. A substantial decrease in velocity of a light wave moving through the solid hair sample arguably results in an increase of the electromagnetism, wavelengths per metre, compared with the radiation moving at the speed of light in a vacuum. This effect was not observed for melanin in solution where the reduction in velocity is likely to be less pronounced, but was also observed when dopa melanin was embedded in a solid agar matrix [2].
Light photons interact with matter in a quantised way, initiating electronic transitions if allowed, with the promotion of an electron from a ground to excited state. The electronic transition has a discrete energy equivalent to the photon energy. The excited state does not persist and excess energy is lost in a variety of ways, with the electron falling back eventually to the ground state. Excited triplet states are paramagnetic and arguably the conversion of a ground state non-paramagnetic molecule to a paramagnetic triplet state suggests the incorporation of material with magnetism into the molecule. Following absorption and photochemical reaction, light quanta behave similarly to molecules participating in chemical reactions, in accord with Avogadro’s Hypothesis. There have been a number of studies to attempt to measure the charge and mass of the photon, with disparate orders of magnitude (as summarised in the paper by Hankins et al published in 2013 [14]). Despite this, the authors of the 2005 review [1] conclude that up to that point there had been no conclusive evidence for a mass of the photon. All previous studies had attempted to measure the mass or charge of the photon when it was travelling in free space or air. The notable difference between this current experiment and previous studies, is that this obtains a value for photon charge in an experiment where photons are at the point of impact with an absorbing molecule, and arguably brought to rest or in a highly condensed form, immediately prior to absorption. It is at this point where the electromagnetism will be most concentrated in space. The closest study to this experiment, published after 2005, is that described by Hankins et al [14] which used a laser emitting wavelengths of 667 nm passed in air through an electric field generated between plates of interaction length 5.08 cm. They measured the deflection to estimate an upper bound photon to electron charge ratio (q/e) of 10−14. Here, a pulse of laser irradiation of wavelength 694 nm was directed onto a hair sample containing melanin, which was estimated to absorb 6 – 10 J irradiation or 2.2 – 3.6 x 1019 red light photons. From this a photon charge can be determined to be 3.1 – 6.1 x 10−25 coulombs per photon. The photon charge from the Hankins et al study is 1.6 x 10−33 coulombs. This is clearly a very different order of magnitude, but this is possible if the charge in a wave moving in air is less condensed, which is the case in the Hankins et al experiment, than that at the molecular interface immediately prior to absorption, which is the case in the experiment described here.
In this experiment the wavelength of laser irradiation is 694 nm or 694 x 10−9 m. According to wave theory, this distance measured for the wave moving in space implies there will be in a 1 m distance in space, 1 / 694 x 10−9 m or 1.4 x 106 wavelengths. The frequency of a wave is invariant as set by the electronic oscillation at source (for red light the frequency is 4.2 x 1014 Hz or 4.2 x 1014 emissions per second) [12]. As explained above, if the frequency remains constant, the velocity and wavelength both decrease when the wave moves from air into a more-dense medium. 2.2 – 3.6 x 1019 photons in the laser pulse in this experiment are calculated to be concentrated at the molecular absorption interface, after the wave slows down upon entering the solid keratin protein of the hair. The photons emitted by the laser are in phase, and perhaps uniquely in this experiment, the wavefronts will be aligned and additive. This will also be applicable to the charge, magnetism and mass at the point of molecular impact of the wavefront with the absorbing molecule melanin, hence the possibility of an interaction with the external magnetic field collectively by the additive charge of 2.2-3.6 x 1019 photons (mean 2.9 x 1019 photons), which is measured to be 3.1 – 6.1 x 10−25 coulombs per photon (mean 4.6 x 10−25 coulombs per photon). The wavelength of a photon travelling in a solid is not known, nor the degree of compression upon molecular collision, but the measured charge would be expected to be lower should the experiment be undertaken for the same number of photons moving in air. 2.9 x 1019 photons in this experiment, in one pulse of laser irradiation, are concentrated in a volume of the incident area on the surface of the hair, multiplied by the depth of penetration of the radiation. This can only be estimated: 1 cm2 beam has a diameter 1.13 cm or 0.0113 m; the width of the hair taken is taken to be 1 mm or 0.001 m which gives an area of 1.13 x 10−5 m2. If the depth of penetration is taken to be one 100 nm or 100 x 10−9 m, then the volume in which the charge is concentrated, or penetration volume, is 11.76 x 10−12 m3. The total charge in the penetration volume on the hair surface is calculated to be 4.6 x 10−25 coulombs per photon multiplied by 2.9 x 1019 photons which is 13.3 x 10−6 coulombs. This equates to a charge density at the surface of the hair in the ‘penetration volume’ of 11.76 x 106 coulombs per m3. If the same number of photons were moving in air rather than concentrated at the hair surface, then the charge density of the photons would be lower. If 2.9 x 1019 photons were hypothetically occupying a volume of the same irradiation area but 1 m length in space, then the volume occupied by the charge would be 11.3 x 10−6 m3. The calculated charge density in air would then be 1.176 coulombs per m3. This is summarised in Figure 8.
The photon charge, as measured in this experiment where the photons are at the point of collision, would be expected to be higher than that measured in experiments where the photons are moving in air and the charge density is lower. Thus, it could be argued that the charge of the laser photons when moving in air, compared to when they collide with an absorbing molecule, would be estimated to be ‘diluted’ by a factor of the ratio of the charge density at the point of impact with the hair (11.76 x 106 coulombs m−3) to the photon density in air (1.176 coulombs m−3) which is 10 x 106. The mean charge per photon determined in this experiment of 4.6 x 10−25 coulombs ‘diluted’ by 10 x 106 is 4.6 x 10−32 coulombs per photon. This is close to that measured by Hankins et al to be 1.6 x 10−33 coulombs per photon. Expressed in relation to the charge of the electron q/e of 2.9 x 10−6 determined in this experiment for the point of impact at the hair surface in the ‘penetration volume’ being 10 x 106 lower or 2.9 x 10−13. The range of previous laboratory-based q/e measurements in air, four of which used lasers as a photon source, are 10−14 to 10−17. Astrophysical measurements, involving photons moving in space, range from 10−28 to 10−46 in studies cited by Hankins et al (Summarised again in Table 3).
Table 3
Laboratory-based studies in air
|
q/e (measured photon charge/ electron charge)
|
Astrophysical studies in space
|
q/e (measured photon charge/ electron charge
|
1961 Grodzins et al
|
10−15
|
1992 Cocconi
|
10−28
|
1967 Stover et al
|
10−16*
|
1994 Cocconi and Raffelt
|
10−28
|
1980 Grassi Strini et al
|
10−17*
|
2005 Kobychev and Popov
|
10−31 and 10−33
|
2003 Semertzidis et al
|
10−16*
|
2007 Altschul
|
10−32 and 10−46
|
2013 Hankins et al
|
10−14*
|
2010 Sivaram and Arun
|
10−30
|
* laser as photon source
It is concluded that an ‘off resonance’ in a time scan to monitor the formation of a laser-induced melanin radical at constant magnetic field, reflects an interaction between charged and magnetic coherent laser photons in phase and the applied magnetic field. A 72% drop in the radical signal equates to a field shift of 0.0004 T during laser firing. Using this and the calculated number of absorbed 694 nm red photons, a red photon charge at the point of molecular collision and interface between travelling in air and molecular absorption, is determined to be 3.1– 6.1 x 10−25 coulombs per photon which would be lower, by an estimated 10 x 106 order of magnitude, if the measurement of charge was from an experiment undertaken where the same number of photons were moving in air. The calculated ‘collision’ photon charge relative to the electron charge (q/e), from the data, approaches 3 x 10−6 which would be in a similar range to the photon mass to electron mass ratio calculated using Einstein’s equation E = mc2. Photons interacting with matter are absorbed, transmitted, reflected, refracted or scattered. Reflection occurs at highly polished metallic surfaces, and here photons behave as particles undergoing an elastic collision involving change of momentum. Photon collision with the molecules in glass must differ from collision with polished metals. Glass is covalent in structure with discrete localization of electrons in covalent bonds. This contrasts metals where electrons move freely in extensive conduction bands covering many atoms. The possibility of an encounter with a negative electrical field is therefore higher in metals than in glass where electrons are not delocalised. Refraction occurs in glass if angle of incidence of the light is < 90o, and could reflect some electrostatic repulsion between photons with a negative charge and the discretely localised electrons of the silica molecules. The phenomena of diffraction and interference are not readily explained by a particle property of light. A monochromatic light source is directed on to slits such that two wave trains are generated with a constant phase difference. Diffraction is most pronounced when the width of the slit is similar to the wavelength. It also occurs with electrons, protons and neutrons as well as electromagnetic radiation. If the wave train is viewed as a stream of particles with negative electric charge, not unlike, but much smaller than electrons, diffraction might be due to slight deflection of the particles due to repulsive forces between the negative charge of the photons and the electric field of the molecules forming the sides of the slit. For wave-trains with a regular phase difference this deflection will be constant for the different wave trains and augmentation will occur in regions of energy overlap (light areas) and areas of no photons resulting in dark bands. In addition, the ability of photons to integrate with electrons in atoms, and cause electronic excitation, could suggest that photons carry a negative charge. Further work is needed here, but the contradictions and complexity surrounding photon mass measurements would be explicable if the motion of the photons and measurement conditions are taken into account and this study strongly supports the previous work of others in this field, that photons are charged particles with mass.
All data generated or analysed during this study are included in this published article and its Supplementary Information file.