{
  "id": 55804,
  "title": "How the initial position & momentum are measured?",
  "url": "/competitions/trackml-particle-identification/discussion/55804",
  "author_name": "",
  "post_date": "2018-05-02T00:10:07.581788600Z",
  "votes": 1,
  "comment_count": 5,
  "views": 0,
  "content": "<p>Maybe this is more physics oriented question, I wonder how can we measure the initial position &amp; momentum in <code>particles</code> data.</p>\n\n<p>I have two questions.</p>\n\n<ul>\n<li>How to define when is the \"initial\" time</li>\n<li>Is it possible to measure position &amp; momentum simultaneously? I guess quantum mechanics does not allow measuring both value at the same time.</li>\n</ul>",
  "messages": [
    {
      "id": "321812",
      "postDate": "05/02/2018 00:10:07",
      "content": "<p>Maybe this is more physics oriented question, I wonder how can we measure the initial position &amp; momentum in <code>particles</code> data.</p>\n\n<p>I have two questions.</p>\n\n<ul>\n<li>How to define when is the \"initial\" time</li>\n<li>Is it possible to measure position &amp; momentum simultaneously? I guess quantum mechanics does not allow measuring both value at the same time.</li>\n</ul>",
      "rawMarkdown": "Maybe this is more physics oriented question, I wonder how can we measure the initial position &amp; momentum in `particles` data.\n\nI have two questions.\n\n - How to define when is the \"initial\" time\n - Is it possible to measure position &amp; momentum simultaneously? I guess quantum mechanics does not allow measuring both value at the same time.",
      "votes": null
    },
    {
      "id": "321813",
      "postDate": "05/02/2018 00:17:58",
      "content": "<p>AFAIK these events happen so fast as to be indiscernible.\nThe data we are provided is a simulation which is why we are able to have the initial particle data. That initial start condiditon is feed into the simulation to produce the data for the compitetion.</p>",
      "rawMarkdown": "AFAIK these events happen so fast as to be indiscernible.\nThe data we are provided is a simulation which is why we are able to have the initial particle data. That initial start condiditon is feed into the simulation to produce the data for the compitetion.",
      "votes": null
    },
    {
      "id": "321849",
      "postDate": "05/02/2018 02:41:14",
      "content": "<p>Oh, so the all the data is produced by simulation and not the actual measured value at CERN??</p>",
      "rawMarkdown": "Oh, so the all the data is produced by simulation and not the actual measured value at CERN??",
      "votes": null
    },
    {
      "id": "321868",
      "postDate": "05/02/2018 04:00:54",
      "content": "<p>Right.  </p>",
      "rawMarkdown": "Right.",
      "votes": null
    },
    {
      "id": "321936",
      "postDate": "05/02/2018 07:16:59",
      "content": "<p>Yes, indeed. We <em>simplified</em> the problem a little bit, in order make it well defined. In 'real world', we couldn't be defining a scoring function based on truth from the simulation.</p>\n\n<p>The initial positions of particles could be obtained by fitting the measurements with a trajectory hypothesis, however, that's not required for this challenge, what we would like to have simply the grouping of measurements (aka hits) that you guys think emerged from the initial particles. </p>",
      "rawMarkdown": "Yes, indeed. We *simplified* the problem a little bit, in order make it well defined. In 'real world', we couldn't be defining a scoring function based on truth from the simulation.\n\nThe initial positions of particles could be obtained by fitting the measurements with a trajectory hypothesis, however, that's not required for this challenge, what we would like to have simply the grouping of measurements (aka hits) that you guys think emerged from the initial particles.",
      "votes": null
    },
    {
      "id": "322977",
      "postDate": "05/04/2018 04:16:10",
      "content": "<p>Understood, thank you for kind reply!</p>",
      "rawMarkdown": "Understood, thank you for kind reply!",
      "votes": null
    }
  ],
  "comments": [
    {
      "id": 321813,
      "author_name": "mcvicuna",
      "author_url": "",
      "post_date": "05/02/2018 00:17:58",
      "content": "<p>AFAIK these events happen so fast as to be indiscernible.\nThe data we are provided is a simulation which is why we are able to have the initial particle data. That initial start condiditon is feed into the simulation to produce the data for the compitetion.</p>",
      "votes": null,
      "replies": []
    },
    {
      "id": 321849,
      "author_name": "corochann",
      "author_url": "",
      "post_date": "05/02/2018 02:41:14",
      "content": "<p>Oh, so the all the data is produced by simulation and not the actual measured value at CERN??</p>",
      "votes": null,
      "replies": [
        {
          "id": 321868,
          "author_name": "mcvicuna",
          "author_url": "",
          "post_date": "05/02/2018 04:00:54",
          "content": "<p>Right.  </p>",
          "votes": null,
          "replies": []
        },
        {
          "id": 321936,
          "author_name": "asalzburger",
          "author_url": "",
          "post_date": "05/02/2018 07:16:59",
          "content": "<p>Yes, indeed. We <em>simplified</em> the problem a little bit, in order make it well defined. In 'real world', we couldn't be defining a scoring function based on truth from the simulation.</p>\n\n<p>The initial positions of particles could be obtained by fitting the measurements with a trajectory hypothesis, however, that's not required for this challenge, what we would like to have simply the grouping of measurements (aka hits) that you guys think emerged from the initial particles. </p>",
          "votes": null,
          "replies": []
        },
        {
          "id": 322977,
          "author_name": "corochann",
          "author_url": "",
          "post_date": "05/04/2018 04:16:10",
          "content": "<p>Understood, thank you for kind reply!</p>",
          "votes": null,
          "replies": []
        }
      ]
    }
  ],
  "raw_markdown_by_id": {
    "321812": "Maybe this is more physics oriented question, I wonder how can we measure the initial position &amp; momentum in `particles` data.\n\nI have two questions.\n\n - How to define when is the \"initial\" time\n - Is it possible to measure position &amp; momentum simultaneously? I guess quantum mechanics does not allow measuring both value at the same time.",
    "321813": "AFAIK these events happen so fast as to be indiscernible.\nThe data we are provided is a simulation which is why we are able to have the initial particle data. That initial start condiditon is feed into the simulation to produce the data for the compitetion.",
    "321849": "Oh, so the all the data is produced by simulation and not the actual measured value at CERN??",
    "321868": "Right.",
    "321936": "Yes, indeed. We *simplified* the problem a little bit, in order make it well defined. In 'real world', we couldn't be defining a scoring function based on truth from the simulation.\n\nThe initial positions of particles could be obtained by fitting the measurements with a trajectory hypothesis, however, that's not required for this challenge, what we would like to have simply the grouping of measurements (aka hits) that you guys think emerged from the initial particles.",
    "322977": "Understood, thank you for kind reply!"
  },
  "source": "meta"
}