Herbert Fröhlich, FRS (1905–1991)—A Physicist Ahead of His Time

Abstract

This contribution records the key events in Fröhlich's life, and discusses his most influential contributions, ranging from meson theory to biology, many of which will be seen to be the result of a ‘cross-fertilisation’ of some kind. Most influential was undoubtedly his introduction of the concepts and techniques of quantum field theory into solid-state physics in the early 1950s, which not only predicted a phonon-induced electron-electron attraction as the basic interaction underlying the phenomenon of superconductivity, but also – more importantly – completely revolutionised the future development of both solid-state and many-body physics. Even more revolutionary, however, was his introduction, in the mid 1960s, of concepts of modern theoretical physics – in particular, that of coherence – into the open, dissipative systems encountered in biology, in a highly novel attempt to understand the orderly functioning of living systems. Less well known and appreciated was his continued interest in particle physics, dating from his pre-war work on meson theory and which, with attempts to understand the separation of Dirac particles into leptons and quarks, continued up to the time of his death.

The hallmark of his particular genius was an ability to balance the radical with the conservative: to realise when new ideas had genuinely to be introduced and when they did not. This, coupled with a truly holistic outlook and constant alertness to the possibility that certain concepts might well have a relevance to fields other than those in which they had first arisen, helped resolve some of the most enigmatic mysteries of the physics of his era.

Keywords:

• Fröhlich Hamiltonian
• Herbert Fröhlich
• Meson theory
• Living systems
• Quantum biology
• Quantum field theory

Notes

¹In this circumstance, a quite different approach is required, which again was initiated by Fröhlich some years later from considerations of Debye loss, and which subsequently developed into what is now known as “small” polaron theory.

²As we shall see later, the suggestion of blood was particularly perceptive.

³This is one of the many important points first made in his book Theory of Dielectrics [[11]].

⁴In the present case, the total number of polarization quanta is fixed as a consequence of the competition between the dissipation inherent in the system and the metabolic pumping; thus, as in the case of a fixed number of material particles, a chemical potential can again be introduced, so permitting the possibility of a redistribution of polarization quanta amongst the modes, analogous to that which occurs in Einstein condensation in a gas of material bosons.

⁵It is important to realize that this does not entail any contradiction with the second law of thermodynamics since there is a corresponding increase in the entropy elsewhere in the system.

⁶ Field theoretically, this is equivalent to the occupation number of this mode (the condensate) becoming macroscopically large.

⁷For further details see Hyland [[26]].

⁸In order that the coherent excitation survive in the presence of frictional damping it is necessary that the endogenously available power be sufficiently large. For the value of the power threshold, s₀, depends on the level of dissipation in the system, which includes any contribution from viscous damping by cell water, for example, that might be present. An interesting and important case of a coherent oscillation on which viscous damping is minimal is the (metabolically maintained) longitudinal oscillation of microtubules in the brain; for here, the interplay between material properties peculiar to these objects results in “slip” boundary conditions [[29]].

⁹It should be noted that the failure of other attempts (e.g., Furia et al. [[35]] and Gos et al. [[36]]) to reproduce the (positive) effect found by Grundler et al. [[31]] do not necessarily invalidate the latter, on account of crucial differences in experimental protocol, which undermined the fidelity of the purported replications.

¹⁰A similar trend was found (at intensities as low as 10⁻¹⁴ W/m²) in subsequent Russian work done during the 1990s on the conformational state of the genome in E. coli, which strongly suggests that chromosomal DNA is the target of the resonant interaction of mm microwaves with this system [[37]].

¹¹This is frequency is close to the modulation frequency used by Grundler and Kaiser [[31]] in their experiments on the same strain of yeast.

¹²In this connection it should be appreciated that because of the longitudinality of Fröhlich's coherent excitation (in bulk), radiation from it can only arise as a side-effect of the existence of internal bounding surfaces that endow the excitation with a certain degree of tranversality [[26]].

¹³See footnote 15 and associated text.

¹⁴It should be appreciated that such triggering might well be only the first of a whole sequence of processes that have to be realized before a particular nonthermal effect manifests itself [[23]].

¹⁵The time is minimum when the frequency of the external field matches that of the coherent mode whose excitation is being triggered by the field [[64]].