"null infinity" meaning in English

{
  "etymology_text": "From the physics concept of \"at infinity\" or \"far\", where fields are small, and the math concept of null set. Ironically, a null infinity may be neither far nor a null set.",
  "forms": [
    {
      "form": "null infinities",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "null infinity (plural null infinities)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "In a closed space-time, especially for an Einstein cylinder, null infinity for a given point is the limit of convergence of the light cone most distant from the given point. That is, it is the limit of a set of points that each have a time-like separation from every point that has a space-like separation from the given point."
      ],
      "id": "en-null_infinity-en-noun-S-w6gGBu",
      "links": [
        [
          "closed",
          "closed"
        ],
        [
          "space-time",
          "space-time"
        ],
        [
          "Einstein cylinder",
          "Einstein cylinder"
        ],
        [
          "light cone",
          "light cone"
        ],
        [
          "time-like",
          "time-like"
        ],
        [
          "separation",
          "separation"
        ],
        [
          "space-like",
          "space-like"
        ]
      ]
    }
  ],
  "word": "null infinity"
}

{
  "etymology_text": "From the physics concept of \"at infinity\" or \"far\", where fields are small, and the math concept of null set. Ironically, a null infinity may be neither far nor a null set.",
  "forms": [
    {
      "form": "null infinities",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "null infinity (plural null infinities)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "In a closed space-time, especially for an Einstein cylinder, null infinity for a given point is the limit of convergence of the light cone most distant from the given point. That is, it is the limit of a set of points that each have a time-like separation from every point that has a space-like separation from the given point."
      ],
      "links": [
        [
          "closed",
          "closed"
        ],
        [
          "space-time",
          "space-time"
        ],
        [
          "Einstein cylinder",
          "Einstein cylinder"
        ],
        [
          "light cone",
          "light cone"
        ],
        [
          "time-like",
          "time-like"
        ],
        [
          "separation",
          "separation"
        ],
        [
          "space-like",
          "space-like"
        ]
      ]
    }
  ],
  "word": "null infinity"
}