"scallop theorem" meaning in English

{
  "etymology_text": "From an explanation of a principle of fluid dynamics given by E. M. Purcell.",
  "forms": [
    {
      "form": "scallop theorems",
      "tags": [
        "plural"
      ]
    }
  ],
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      "args": {},
      "expansion": "scallop theorem (plural scallop theorems)",
      "name": "en-noun"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
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          "kind": "other",
          "name": "English entries with incorrect language header",
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          "langcode": "en",
          "name": "Fluid dynamics",
          "orig": "en:Fluid dynamics",
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      ],
      "glosses": [
        "A theorem which states that to achieve propulsion at low Reynolds number in simple (i.e. Newtonian) fluids, a swimmer must deform in a way that is not invariant under time-reversal."
      ],
      "id": "en-scallop_theorem-en-noun-Qry0qm-U",
      "links": [
        [
          "fluid dynamics",
          "fluid dynamics"
        ],
        [
          "Reynolds number",
          "Reynolds number"
        ],
        [
          "Newtonian",
          "Newtonian fluid"
        ],
        [
          "invariant",
          "invariant"
        ],
        [
          "time-reversal",
          "time reversal"
        ]
      ],
      "raw_glosses": [
        "(fluid dynamics) A theorem which states that to achieve propulsion at low Reynolds number in simple (i.e. Newtonian) fluids, a swimmer must deform in a way that is not invariant under time-reversal."
      ],
      "topics": [
        "fluid-dynamics",
        "natural-sciences",
        "physical-sciences",
        "physics"
      ]
    }
  ],
  "word": "scallop theorem"
}

{
  "etymology_text": "From an explanation of a principle of fluid dynamics given by E. M. Purcell.",
  "forms": [
    {
      "form": "scallop theorems",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
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      "expansion": "scallop theorem (plural scallop theorems)",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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    {
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        "English countable nouns",
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        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
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        "en:Fluid dynamics"
      ],
      "glosses": [
        "A theorem which states that to achieve propulsion at low Reynolds number in simple (i.e. Newtonian) fluids, a swimmer must deform in a way that is not invariant under time-reversal."
      ],
      "links": [
        [
          "fluid dynamics",
          "fluid dynamics"
        ],
        [
          "Reynolds number",
          "Reynolds number"
        ],
        [
          "Newtonian",
          "Newtonian fluid"
        ],
        [
          "invariant",
          "invariant"
        ],
        [
          "time-reversal",
          "time reversal"
        ]
      ],
      "raw_glosses": [
        "(fluid dynamics) A theorem which states that to achieve propulsion at low Reynolds number in simple (i.e. Newtonian) fluids, a swimmer must deform in a way that is not invariant under time-reversal."
      ],
      "topics": [
        "fluid-dynamics",
        "natural-sciences",
        "physical-sciences",
        "physics"
      ]
    }
  ],
  "word": "scallop theorem"
}