Gas

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Comment by Alex Armstrong on August 28th, 2017 at 12:13 pm

To whom it may concern,

I am writing to seek clarification on a few phrases in this article that are unclear to members of the public. I am a Ph.D student at UC Irvine studying physics. While explaining the formation of stars to a members of the public, they objected that gases always expand and cited this article as evidence of their point. They pointed to the following quotes:
“Matter in the gas state characteristically has no independent shape or volume and tends to expand indefinitely to fill any enclosure.”
“Following the second law of thermodynamics, gas particles will immediately diffuse to homogeneously fill any shape or volume of space that is made available to them.”
“Unlike liquids, however, unconstrained gases do not occupy a fixed volume, but expand to fill whatever space they can occupy.”
While I see the attempt to leave things open for cases of stellar formation, phrases like “tends to expand”, “made available to them”, “whatever space they can occupy”, are not clear enough. They would be improved by saying “tends to expand unless…”, “fill any shape or volume of space defined by a material boundary or potential energy barrier” , “fill whatever space is available to them as defined by material boundaries or potential energy barriers.”

If it is not possible to make these updates, a simple response from the author of this article expressing agreement with my interpretation of these phrases would help me in teaching physics to the public.

Much appreciation,

Alex Armstrong

Comment by Jennifer Tanabe on August 29th, 2017 at 10:06 am

Thank you, Alex, for your comment. I find it surprising that “the public” finds the term “any enclosure” unclear. Nevertheless, your point is well taken and the text will be revised to clarify the confusion.

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