Talk:Rollin film

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Untitled[edit]

I deleted the cleanup tag, as it didn't appear that this article was in excessive disorder. You can put it back up if you disagree, but please post your reasons why here. Stephen (talk) 05:33, 14 May 2009 (UTC)[reply]

Video?[edit]

Does anyone have a video of this? It would be an excellent addition to the article. Axl ¤ [Talk] 12:44, 4 February 2010 (UTC)[reply]

Is a Rollin film visible?[edit]

At 30nm thickness, I suspect it's invisible. More specifically, I don't know what to make of this sentence in the paragraph about fountains: "If not for its evaporation in the presence of heat, a Rollin film would have a very low index of refraction". Does that mean that, because it can evaporate, the refractive index of a Rollin film is not low??? I'm inclined to delete the sentence, but maybe someone knows what the the original author meant to say. It could be replaced with a statement that, because of the low refractive index, the films are not visible. Spiel496 (talk) 14:44, 18 June 2010 (UTC)[reply]

Xkcd[edit]

this "what if" from xkcd brought me here, and it did provide another reference that might be used to expand the article . But it's all a bit beyond my physics skills EdwardLane (talk) 13:45, 18 June 2013 (UTC)[reply]

Relation to fountain effect unclear[edit]

I do not agree with the sentence: "Rollin films are involved in the fountain effect where superfluid helium leaks out of a container in a fountain-like manner." Fountain effect is primarily caused by mechano-caloric force, which is not directly related to Rollin film. I suggest to remove the sentence, unless it is explained better how Rollin films are involved and citation is provided. Ondrej Kincl (talk) 07:50, 26 July 2023 (UTC)[reply]

The source of energy for superfluid helium's wall climb should be explained more clearly.[edit]

I think the article should clearly explain the source of energy which superfluid helium uses to fight gravity while climbing up the wall of a vessel to escape it. It should be adhesion to the vessel's wall probably, but intuitively the vessel must be even colder by a fraction of a kelvin than the helium it holds, else helium would heat up and stop being a superfluid. So how can energy flow from a colder object to a warmer one, with regards to law of thermodynamics (provided an artificial heat-pump is not being operated in that setup)?

(Also, the vessel could theoretically be as tall as reaching low-earth orbit and superfluid helium would still climb all the way up. So even if helium is very light, the total work done against Earth's gravity would still imply a very large amount of energy used. Such a vessel could evenbe open-topped, allowing superfluid helium to fly away to to outer space at the end of its journey, thereby the energy of climb is never recovered to Earth. That sounds suspiciously close to a cost-free space elevator, i.e. perpetuum mobile) 92.249.156.179 (talk) 12:29, 25 September 2023 (UTC)[reply]

Third sound[edit]

Third sound links here, but it isn't so obvious why. Could we make this more obvious? Gah4 (talk) 00:23, 29 September 2023 (UTC)[reply]