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What's more interesting to me than HEP is how HEP became such a big deal. I asked on HN before why people find HEP interesting and the responses were enlighteni

What's more interesting to me than HEP is how HEP became such a big deal. I asked on HN before why people find HEP interesting and the responses were enlightening to me as someone who finds HEP boring: https://news.ycombinator.com/item?id=23322857 https://news.ycombinator.com/item?id=23322857 Personally, I find turbulence much more interesting. The fact that it's orders of magnitude more important than HEP and also very intellectually challenging should give pause to those who have dedicated their lives to HEP. But my impression is that cultural forces have unfortunately convinced many of our best and brightest to go into HEP or other similarly impractical areas of physics. I guess that's better than working for Facebook to make people click on ads, but that's setting the bar low. If you're interested in physics, you can make a much better choice than HEP. (If you're open to areas outside of physics you may be able to make an even better choice.) I can see why someone might view the "building blocks" of the universe as fundamental or how there are interesting philosophical questions that HEP can address. But turbulence is fairly ubiquitous; certainly that makes it "fundamental" in some sense. And there are philosophical implications of chaos and statistical mechanics; turbulence is part of both.

SiempreViernes 6y ago
I too have waved my hand in the smoke from a snuffed candle, and sure it's fun for a while but pretty soon it just becomes a big mundane mush and I go out to look at the stars instead.
leephillips 6y ago
Scientists are trained to accept a philosophical stance that regards particle physics are more fundamental than turbulence. Most have never critically questioned the meaning of “fundamental” in physics: https://arstechnica.com/science/2018/10/turbulence-the-oldest-unsolved-problem-in-physics/ https://arstechnica.com/science/2018/10/turbulence-the-oldes...
- whatshisface 6y ago
  You can explain how turbulence arises from particles, but you can't explain how particles arise from turbulence, because they don't...
thomasahle 6y ago
I think the scientific questions are just bigger in HEP, even if turbulence has more interesting engineering questions. Those are just fundementally differ t to different people.
- piannucci 6y ago
  This! To my understanding, as a dilettante in the science of fluids, turbulence is an open problem mostly only in subfields pretty far removed from everyday engineering: The mathematicians question whether the Navier-Stokes continuum fluid model can be trusted to remain mathematically well-posed in all scenarios; but Navier-Stokes is just a second-order approximation to Boltzmann transport, and higher-order approximations are well known. If N-S were to blow up, it would merely indicate that the second-order approximation breaks down in some regime, necessarily involving shocks. But... I don’t think any experts in transport theory would be surprised by that. It would be more be like solving the mystery of rogue waves, and less like finding bigfoot. The other group I’m aware of are those who study large-scale turbulence. The goal there is to summarize or coarse-grain the turbulence that goes on within a small computational volume, as a cost-saving measure versus using a more finely-resolved mesh in space and time. That’s valuable work with true social impact, such as in atmospheric forecasting and erosion studies. But... it’s kinda phenomenological. Not as much fun for many scientists.
  - btrettel 6y ago
    > To my understanding, as a dilettante in the science of fluids, turbulence is an open problem mostly only in subfields pretty far removed from everyday engineering: > The other group I’m aware of are those who study large-scale turbulence. The goal there is to summarize or coarse-grain the turbulence that goes on within a small computational volume, as a cost-saving measure versus using a more finely-resolved mesh in space and time. [...] But... it’s kinda phenomenological. Not as much fun for many scientists. The turbulence "closure" problem you describe here is the main obstacle for the prediction of any turbulent flow. This is not far removed from everyday engineering! Practically speaking, the computational complexity of turbulence is far too high, so approximations become necessary. You've described the basic idea behind large-eddy simulation, but I think you underestimate how interesting the theory could be there. Look into spectral theories of turbulence. I find this sort of research rather interesting, though it's formidable. My understanding is that some of the techniques Kraichnan applied to turbulence in the late 1950s were later independently redeveloped by quantum field theorists in the 1970s. (Note that I'm no expert in these models, but learning about them is on my TODO list.) > The mathematicians question whether the Navier-Stokes continuum fluid model can be trusted to remain mathematically well-posed in all scenarios The media unfortunately gives the wrong impression about the Navier-Stokes existence and uniqueness problem. This problem doesn't have much to do with turbulence in the computational complexity sense. I honestly don't see how proving that the Navier-Stokes equations do or do not have unique solutions is going to help turbulence. They've already proved that for 2D turbulence, but that didn't help solve 2D turbulence. Anyway, your understanding of the problem is basically correct if not focused on the best examples. It's already known that the solutions aren't unique in inviscid compressible flows, but that doesn't stop people from using the compressible Euler equations as a model. They just add an extra condition to make the solutions unique (arguing that the other solutions won't appear in reality). My impression is that many people working on the NS existence problem believe that in certain circumstances the dissipation can become unbounded, and would be limited by different physical mechanisms that should be used instead. Practically speaking this might solved by simply using a different viscosity model, for instance.
asib 6y ago
I think hoping that people who enter academia will go into areas with significant practicality is a path that will lead to despair. Some people just like what they like though. I studied computer science and really enjoyed the more abstract mathematical stuff like type theory and semantics. Probably less applicable than something like machine learning or robotics or NLP, but I like what I like. Also, someone may have already mentioned this in response to your other post, but perhaps people are interested in things like astronomy and HEP precisely because they're so far removed from common experience. That was part of my personal interest in quantum computing (and as a corollary, QM).
bobdole12345 6y ago
What makes you think people aren't looking at turbulence? The difference is that you don't need a partnership of a dozen large governments to swirl things in a coffee cup, but you do if you want to expand on the previous generation of collider.

SiempreViernes 6y ago

I too have waved my hand in the smoke from a snuffed candle, and sure it's fun for a while but pretty soon it just becomes a big mundane mush and I go out to look at the stars instead.

leephillips 6y ago

Scientists are trained to accept a philosophical stance that regards particle physics are more fundamental than turbulence. Most have never critically questioned the meaning of “fundamental” in physics: https://arstechnica.com/science/2018/10/turbulence-the-oldest-unsolved-problem-in-physics/ https://arstechnica.com/science/2018/10/turbulence-the-oldes...

whatshisface 6y ago
You can explain how turbulence arises from particles, but you can't explain how particles arise from turbulence, because they don't...

thomasahle 6y ago

I think the scientific questions are just bigger in HEP, even if turbulence has more interesting engineering questions. Those are just fundementally differ t to different people.

piannucci 6y ago
This! To my understanding, as a dilettante in the science of fluids, turbulence is an open problem mostly only in subfields pretty far removed from everyday engineering: The mathematicians question whether the Navier-Stokes continuum fluid model can be trusted to remain mathematically well-posed in all scenarios; but Navier-Stokes is just a second-order approximation to Boltzmann transport, and higher-order approximations are well known. If N-S were to blow up, it would merely indicate that the second-order approximation breaks down in some regime, necessarily involving shocks. But... I don’t think any experts in transport theory would be surprised by that. It would be more be like solving the mystery of rogue waves, and less like finding bigfoot. The other group I’m aware of are those who study large-scale turbulence. The goal there is to summarize or coarse-grain the turbulence that goes on within a small computational volume, as a cost-saving measure versus using a more finely-resolved mesh in space and time. That’s valuable work with true social impact, such as in atmospheric forecasting and erosion studies. But... it’s kinda phenomenological. Not as much fun for many scientists.
- btrettel 6y ago
  > To my understanding, as a dilettante in the science of fluids, turbulence is an open problem mostly only in subfields pretty far removed from everyday engineering: > The other group I’m aware of are those who study large-scale turbulence. The goal there is to summarize or coarse-grain the turbulence that goes on within a small computational volume, as a cost-saving measure versus using a more finely-resolved mesh in space and time. [...] But... it’s kinda phenomenological. Not as much fun for many scientists. The turbulence "closure" problem you describe here is the main obstacle for the prediction of any turbulent flow. This is not far removed from everyday engineering! Practically speaking, the computational complexity of turbulence is far too high, so approximations become necessary. You've described the basic idea behind large-eddy simulation, but I think you underestimate how interesting the theory could be there. Look into spectral theories of turbulence. I find this sort of research rather interesting, though it's formidable. My understanding is that some of the techniques Kraichnan applied to turbulence in the late 1950s were later independently redeveloped by quantum field theorists in the 1970s. (Note that I'm no expert in these models, but learning about them is on my TODO list.) > The mathematicians question whether the Navier-Stokes continuum fluid model can be trusted to remain mathematically well-posed in all scenarios The media unfortunately gives the wrong impression about the Navier-Stokes existence and uniqueness problem. This problem doesn't have much to do with turbulence in the computational complexity sense. I honestly don't see how proving that the Navier-Stokes equations do or do not have unique solutions is going to help turbulence. They've already proved that for 2D turbulence, but that didn't help solve 2D turbulence. Anyway, your understanding of the problem is basically correct if not focused on the best examples. It's already known that the solutions aren't unique in inviscid compressible flows, but that doesn't stop people from using the compressible Euler equations as a model. They just add an extra condition to make the solutions unique (arguing that the other solutions won't appear in reality). My impression is that many people working on the NS existence problem believe that in certain circumstances the dissipation can become unbounded, and would be limited by different physical mechanisms that should be used instead. Practically speaking this might solved by simply using a different viscosity model, for instance.

asib 6y ago

I think hoping that people who enter academia will go into areas with significant practicality is a path that will lead to despair. Some people just like what they like though. I studied computer science and really enjoyed the more abstract mathematical stuff like type theory and semantics. Probably less applicable than something like machine learning or robotics or NLP, but I like what I like. Also, someone may have already mentioned this in response to your other post, but perhaps people are interested in things like astronomy and HEP precisely because they're so far removed from common experience. That was part of my personal interest in quantum computing (and as a corollary, QM).

bobdole12345 6y ago

What makes you think people aren't looking at turbulence? The difference is that you don't need a partnership of a dozen large governments to swirl things in a coffee cup, but you do if you want to expand on the previous generation of collider.