Physics of Life (2022) / Chapter Skim
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5 Relation to Other Fields of Physics
5 Relation to Other Fields of Physics
Pages 182-195
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From page 182... ...
While biological physics has an independent existence, many of these new developments are deeply connected to progress in other fields, and this is part of the beauty of physics. This chapter surveys, briefly, some of the many points of contact between biological physics and the broader physics community, summarized even more briefly in Table 5.1.
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From page 183... ...
Conversely, the machine learning methods that are used today in the analysis of raw data from particle physics have their roots in models of brain func tion that began in the biological physics community. On the theoretical side, ideas from quantum field theory are central to thinking about the collective behavior of flocks and swarms, for example, but this reflects the merging of field theory and statistical physics that occurred in the 1970s, in the wake of the renormalization group.
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From page 184... ...
Total internal reflection microscopy, nonlinear methods such as coher ent anti-Stokes Raman microscopy and stimulated Raman scattering microscopy, fluorescence speckle microscopy, light sheet microscopy, structured illumination microscopy, and fluorescence recovery after photobleaching (FRAP) all have had substantial impact on biological physics, and the continued development of these methods by the biological physics community has had an impact on biology more broadly (Chapter 6)
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From page 185... ...
The soft matter community has substantial overlap with the biological physics community, and many soft matter problems are interesting in part because they capture some aspects of living systems in simpler and more easily controlled contexts. As noted in Chapter 3, ideas from polymer physics also have been important in thinking about the structure and dynamics of chromosomes.
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From page 186... ...
In other examples, there is self-assembly of populations of organisms to perform crucial optical functions, as with the symbiosis between clams and algae in Figure 5.2, which also self-assemble. Phases and phase transitions are central to classical statistical mechanics, and a major theme of soft matter physics is to push these concepts beyond their original context of thermal equilibrium.
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From page 187... ...
. The classical statistical physics of disordered systems connects with biologi cal physics through many problems beyond cell movement.
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From page 188... ...
. Theories of neural networks are a rich source of problems in statistical physics, so much so that one of the categories on the electronic archive of physics papers, arXiv.org, is "neural networks and disordered systems." The relation of these statis tical physics problems to real brains is discussed in Chapter 3, and application to the deep networks that are powering the current revolution in artificial intelligence is discussed in Chapter 7.
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From page 189... ...
This stream of work also has emphasized that the equivalence of entropy as a measure of heat flow and entropy as a measure of available information is more than formal, and has physical consequences. Subse quent theoretical work has derived thermodynamic uncertainty relations, which for example connect the precision of molecular scale clocks to the rate of energy dis sipation.
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From page 190... ...
These materials flow, shift, and crack under stress, prototypes of the complex rheology that is a major theme in soft matter physics. Granular materials are collections of particles that interact via repulsive frictional contact forces; they remain solid below a yield stress, and flow frictionally above this stress.
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From page 191... ...
Figure 4d despite obvious physical consequences, became the province of pure mathematics as a function of two-dimensional displacements, indicating that the shows the net velocity field calculated from the same data, indicating system is an extensile active nematic system3,5,15. This feature of the that there is a flow of cells pointing in the direction of the front of the for much of the 20th century, while fluid turbulence drifted out of physics into correlation was flipped and weaker in the case of a cultured myoblast comet shape in +1/2 defects (Fig.
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From page 192... ...
Such spatially extended excitable media support novel excitations, such as spiral waves (see Figure 5.6)
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From page 193... ...
(B) FIGURE 5.6 Spiral waves are supported by spatially extended excitable media, like the signaling systems that slime molds use to communicate.
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From page 194... ...
Regarding the deep history of life on Earth, there are classical experiments showing that early atmospheric conditions allowed for the synthesis of moderately complex organic molecules, including amino acids. But there is a huge gap from this to something one might think of as alive.
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From page 195... ...
R e l at i o n to Other Fields of Physics 195 molecules of life on Earth form a network with special properties, distinguished from a random jumble of molecules of similar size and elemental composition. Perhaps the most important result of thinking more concretely about how to search for life on extra-solar planets is that we are not so sure what features of life on Earth constitute its defining physical characteristics.
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