The Second Law of Thermodynamics — BROKEN!!

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The second law of thermodynamics: the overall entropy, or disorder, of an isolated system which is not in equilibrium will increase over time, approaching a maximum value at equilibrium, or at maximum disorder.
Okay, we all know that, according to the Second Law of Thermodynamics, you cannot unmix liquids after they’ve been mixed, right? Okay, all you smart people, here’s a streaming video for you to watch and to explain, where a mixed solution is unmixed by reversing the stirring process. [2:19].

In the unlikely event that you all get stuck trying to explain how this is done, I’ll post an explanation in exchange for a million dollars!


About GrrlScientist

grrlscientist is the pseudonym of an evolutionary biologist and ornithologist who writes about evolution, ethology, and ecology, especially in birds. After earning a degree in microbiology (thesis focus: virology) and working at the Fred Hutchinson Cancer Research Center in Seattle, she earned her PhD in zoology from the University of Washington in Seattle, where she studied the molecular correlates of testosterone and behaviour in white-crowned sparrows. She then worked a Chapman Postdoctoral Fellow at the American Museum of Natural History in New York City, where she studied the speciation and distribution of lories and other parrots throughout the South Pacific Islands. A discarded scientist, she returned to her roots: writing. Formerly hosted by The Guardian (UK), she now writes about science for Forbes and for the non-profit think tank, the Evolution Institute and she writes podcasts for BirdNote Radio. An avid lifelong birder and aviculturist, she lives with a flock of songbirds and parrots somewhere in Germany.
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0 Responses to The Second Law of Thermodynamics — BROKEN!!

  1. edgarallenpoe says:

    The second law of thermodynamics hasn’t been broken because those fluids did not mix. The entirely laminar flow of the experimental setup is completely reversible.
    If turbulent mixing had occurred, the fluids would not separate in that fashion.

  2. Jeff Knapp says:

    …and, if you notice, it was not perfect. There was indeed a little mixing at the boundaries between the (very viscous) fluids that was not perfectly undone. These fluids appeared to act more like elastic solids that stayed (mostly) separated rather than fluids that were mixing.

  3. Bob O'H says:

    You get the idea, don’t you?
    Were the dyes loaded at the same distance from the centre? If not, I assume they would not actually meet and mix at all, but would only appear to when viewed from the side.

  4. Michael says:


  5. MattXIV says:

    The dyes never got mixed together. The dyed columns of the fluid got pulled out into non-intersecting thin bands by the rotation, which has a faster angular velocity near the center. The slow diffusion of the dye and lack of turbluent flow allowed the bands of dye to be pulled back to to roughly their original columns by reversing the rotation. The concentration of the dye never increased within a particular volume of fluid – the shape of the particular volume was just changed, then the change was reversed.

  6. R Hampton says:

    If paints were used instead of transparent dyes, then you would be able to tell the difference between a true blending of fluids from the blending of light (passed through three very close – but discrete – layers of fluid).

  7. ecoli says:

    My bet, is that halfway through, when he starts rotating the lever in the other direction, he actually started to play the video backwards. The audio is dubbed over.

  8. David Harmon says:

    I’ve seen similar demos before… Commenters #1, 2, 5, and 6 have it right.
    The “messy details” of mixing are a significant field of study in their own right — some people get degrees in “mixology” (dunno the official name), and then go on to lucrative work in various industries. Among other things, those are the folks who ensure that when you open a carton of “fudge ripple” ice-cream, the fudge isn’t puddled at the bottom of the container!

  9. Dale Husband says:

    some people get degrees in “mixology” (dunno the official name),
    What?! You never heard the term CHEMISTRY?

  10. Harold says:

    They are injecting the dye into a gel, not a liquid.

  11. yes, the dyes are injected into a viscous fluid into different areas where the colors will not mix even after they are “mixed”. you guys are good at this!
    anyway, i thought that mixology was the name of the degree that bartenders earn?