Comments by "Lawrence D’Oliveiro" (@lawrencedoliveiro9104) on "Navier-Stokes Equations - Numberphile" video.

  1. 2:09 So only incompressible fluids? That would leave out all gases.
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  2. Being an upside-down delta, It could be a Southern Hemisphere Greek letter. You know, Greek from Australia.
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  3.  @ythehunter755  There were several varieties of Ancient Greek. Consider Classical Greek versus Cretan Linear B Greek.
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  4. 4:39 You could just say it’s a differential equation, and density is the differential of mass.
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  5. 17:06 It makes sense for finite-sized particles, not infinitesimally-small ones. Do I sense a repeat of the whole Planck-oscillator business? That if you take the classical formula down to the zero limit the numbers blow up, but if you stop at a nonzero size, you can get answers that make sense? That are quantized, even? Just suggesting that you stop thinking like a mathematician, and start thinking like a physicist ... ;)
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  6. 2:26 But air, being compressible, means that more mass might be entering a point than leaving it, if the pressure (and hence density) at that point is rising, and conversely if it is falling.
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  7. 18:58 It seems to me you are confusing the physics with the mathematics. The mathematics predicts physically-impossible situations, and you feel that means something is missing in the maths. But it’s not missing there, it’s missing in the physics. Understanding the discrepancy isn’t going to come from any deep insight into Navier-Stokes as it stands, but in altering the model in some way (like introducing the quantization limit I mentioned earlier) to be more physically accurate. Will this lead to new maths? Maybe ... maybe not.
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