Gas molecular attraction in the sense of Newton's law

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Discussion Overview

The discussion centers around the concept of molecular attraction in gases as it relates to Newton's law of universal attraction. Participants explore various observations and theories that may support the idea of gravitational attraction among gas molecules, including astronomical phenomena and the behavior of gases in the atmosphere.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Bernadette questions what experiments or observations demonstrate that gas molecules exhibit attraction in accordance with Newton's law.
  • Some participants suggest that astronomical observations, such as the behavior of gases in nebulas, indicate that gravity keeps these gases together.
  • Others point to atmospheric phenomena, including density gradients and the escape of lighter gases, as evidence of gravitational effects on gases.
  • One participant mentions that the theory of stars, which are held together by gravity, supports the idea of gravitational attraction among gas molecules, noting that Newtonian theory applies to typical stars.
  • Another point raised is that the gravitational force between individual molecules is too small to be measured with current technology.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the evidence for molecular attraction in gases, and the discussion remains unresolved with no consensus reached.

Contextual Notes

The discussion highlights limitations in measuring gravitational forces at the molecular level and the dependence on astronomical observations to infer gravitational effects in gases.

Bernadette
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TL;DR
Attraction between gas
Hello

What experiment or observation shows that for atoms, molecules or masses of gas, there is attraction in the sense of Newton's law (universal attraction)?

Bernadette
 
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Astronomical observations would indicate that the gases in nebulas stay together by gravity. Similarly for the sun composed largely of hydrogen atoms.
 
The atmosphere exhibits all the predicted phenomena of gas under the influence of gravity. Density gradient, buoyancy of less dense gases and pockets of warmer air, the escape of hydrogen and helium from the atmosphere but not heavier gases, and more.

For evidence that gases generate gravity themselves and react to this gravity, astronomical phenomena are perfect examples, as jedishrfu pointed out.
 
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Another example is the theory of stars, which are held together by gravity and hindered to collapse by pressure. For usual stars like our Sun Newtonian theory is sufficient. For, e.g., neutron stars you need general relativity (Tolman-Oppenheimer-Volkoff equation).
 
The gravitational force between two molecules is too small to measure using existing technology.
 

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