Kinetic Theory of Gases

Trusler, J. P. M.

doi:10.1615/atoz.k.kinetic_theory_of_gases

Cited by 2 publications

(4 citation statements)

References 3 publications

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“…Considering collisions as elastic largely stems from laboratory experiments being performed near equilibrium, since virtually any thermal gradient causes convection in a gas. Because temperature cannot evolve during solely elastic collisions, which are conservative, this assumption has since been relaxed; such models are denoted IKTG, where "I" indicates inelastic Many consider inelastic collisions to be a minor occurrence-e.g.,~3% in polyatomics [49]. This fraction is underestimated, as indicated by experimental and theoretical studies of deformation of atoms during collisions in the gaseous state (e.g., [50]), and for additional reasons discussed below.…”

Section: Kinetic Theories Of Gas Elastic and Inelasticmentioning

confidence: 99%

“…The constants in Equation 4are derived from experiments on real gases (baryons). Size of the interacting molecules has an effect on Equation 4, and thus on Equation 5, as exemplified by the modification known as the Van der Waals EOS [49]. Since the equation of state for NBDM is unknown, the proportionality constant may similarly differ from the product NR gc .…”

Section: Gas Temperature Depends On Kinetic Energymentioning

confidence: 99%

“…Researchers in IKTG consider inelastic collisions to be infrequent (e.g., [49]). However, since atoms are not hard spheres (e.g., [50]), as is well-known from inelastic neutron scattering measurements, deformation exists during every collision and so heat should evolve in each interaction [33].…”

Section: Inelastic Collisions and Blackbody Emissionsmentioning

confidence: 99%

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Thermodynamic Constraints on the Non-Baryonic Dark Matter Gas Composing Galactic Halos

Hofmeister

2020

Galaxies

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To explain rotation curves of spiral galaxies through Newtonian orbital models, massive halos of non-baryonic dark matter (NBDM) are commonly invoked. The postulated properties are that NBDM interacts gravitationally with baryonic matter, yet negligibly interacts with photons. Since halos are large, low-density gaseous bodies, their postulated attributes can be tested against classical thermodynamics and the kinetic theory of gas. Macroscopic models are appropriate because these make few assumptions. NBDM–NBDM collisions must be elastic to avoid the generation of light, but this does not permit halo gas temperature to evolve. If no such collisions exist, then the impossible limit of absolute zero would be attainable since the other available energy source, radiation, does not provide energy to NBDM. The alternative possibility, an undefined temperature, is also inconsistent with basic thermodynamic principles. However, a definable temperature could be attained via collisions with baryons in the intergalactic medium since these deliver kinetic energy to NBDM. In this case, light would be produced since some proportion of baryon collisions are inelastic, thereby rendering the halo detectable. Collisions with baryons are unavoidable, even if NBDM particles are essentially point masses. Note that <0.0001 × the size of a proton is needed to avoid scattering with γ-rays, the shortest wavelength used to study halos. If only elastic collisions exist, NBDM gas would collapse to a tiny, dense volume (zero volume for point masses) during a disturbance—e.g., cosmic rays. NBDM gas should occupy central galactic regions, not halos, since self-gravitating objects are density stratified. In summary, properties of NBDM halos as postulated would result in violations of thermodynamic laws and in a universe unlike that observed.

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Section: Kinetic Theories Of Gas Elastic and Inelasticmentioning

confidence: 99%

Section: Gas Temperature Depends On Kinetic Energymentioning

confidence: 99%

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Thermodynamic Constraints on the Non-Baryonic Dark Matter Gas Composing Galactic Halos

Hofmeister

2020

Galaxies

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“…For instance, there can be intra-molecular vibrational and rotational kinetic energy related to the internal molecular structure (there can also be energy related to inter-molecular rotations and vibrations). What is more, real collisions in such gases can involve transfer between such internal degrees of freedom and the translational modes, and such transfers play an important role in determining the outcome of a binary collision between molecules (provided the temperature is not too low) (Trusler [2011]). Consider the analogy of the simplified Boltzmann system: the particles in the gas model are frictionless, and they are not spinning, so when they bounce into each other, the only change that occurs is changes to the speed (and direction) of travel.…”

Section: Exchange Dynamicsmentioning

confidence: 99%

Modelling Inequality

Thébault

Bradley

Reutlinger

2018

The British Journal for the Philosophy of Science

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Econophysics is a new and exciting cross-disciplinary research field that applies models and modelling techniques from statistical physics to economic systems. It is not, however, without its critics: prominent figures in more mainstream economic theory have criticised some elements of the methodology of econophysics. One of the main lines of criticism concerns the nature of the modelling assumptions and idealisations involved, and a particular target are 'kinetic exchange' approaches used to model the emergence of inequality within the distribution of individual monetary income. This paper will consider such models in detail, and assess the warrant of the criticisms drawing upon the philosophical literature on modelling and idealisation. Our aim is to provide the first steps towards informed mediation of this important and interesting interdisciplinary debate, and our hope is to offer guidance with regard to both the practice of modelling inequality, and the inequality of modelling practice.

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Kinetic Theory of Gases

Cited by 2 publications

References 3 publications

Thermodynamic Constraints on the Non-Baryonic Dark Matter Gas Composing Galactic Halos

Thermodynamic Constraints on the Non-Baryonic Dark Matter Gas Composing Galactic Halos

Modelling Inequality

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