{
  "export": {
    "source": "https://urth.darkrealm.vip/thread/urth/6011",
    "note": "Exported from an unofficial mirror of a public mailing list. Copyright in each message remains with the person who wrote it.  Email addresses are obscured as `user at host`, the form the original archive published. This file was rebuilt from parsed fields rather than retained headers, so it is faithful in content but not byte-exact.",
    "addresses": "obscured as 'user at host'"
  },
  "archive": "urth",
  "thread": {
    "id": 6011,
    "subject": "relative time travel",
    "messages": 5,
    "voices": 2,
    "first": "2011-05-14T05:33:42+00:00",
    "last": "2011-05-15T01:09:43+00:00"
  },
  "messages": [
    {
      "message_id": "<4DCE1436.2090802@io.com>",
      "from": {
        "name": "Jeff Wilson",
        "address": "jwilson at io.com"
      },
      "date": "2011-05-14T05:33:42+00:00",
      "subject": "(urth) relative time travel",
      "in_reply_to": null,
      "reply_link": null,
      "blocks": [
        {
          "kind": "quote",
          "depth": 1,
          "text": "See? I suppose this is why I get confused when they talk about travel in\na wormhole being Time-travel. I got lost after your first sentence."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "Let me try the train analogy. I'll number the steps for reference. You \nguys that already know this will see that I have abstracted numerous \ndistracting features out of this account.\n\n1. Each day, a train 600,000 km long (two light seconds) traveling north\nat 90% light speed pulls through a station 600,000 long without slowing.\n\n2. This is being observed by an oppressed native from a very large\ndistance off to one side. One day he notices the train has two new mail \nagents stationed at each end.\n\n2. A hook at the head of the train picks up a bag of outgoing mail from\nthe station. At the same time, the native observes a bag of incoming mail\nbeing picked off by a hook at the entrance of the station platform, and\nthe station clock calls it 12:00:00 .\n\n4. The native observes the light of the pick-up event travel from the\nfront of the train toward the back of the train; they meet just a bit\nsouth of the middle of the platform just a bit over a second later. The\nstation clock reads 12:00:01.\n\n5. Later, the native observes the light from the drop=off event at the\nback reach the front of the train far north of the station. The station\nclock reads 12:00:20.\n\n6. The mail agent at the front of the train sees the pickup happen, then\ndrop-off happen much later.\n\n7.The mail agent at the rear of the train sees the drop-off happen, then\nthe pick-up happen a short time later.\n\n8. The rookie mail agents meet for lunch in the dining car in the middle \nof the train and compare notes of their first day on the high-speed \ntrain. At first, each one thinks their mail transfer happened first, but...\n\n9. ...allowing for the light-lag, the agent at the read admits the one \nat the front must have happened about a second earlier than his so it's \nlight could travel for two seconds and arrive a second afterward.\n\n10. The agent at the front insists that it his transfer must have been \nmore like 18 seconds ahead, because he saw the other transfer 20 seconds \nlater, and the length of the train only accounts for two seconds.\n\n11 The next day, the oppressed native calls on some pagan OT being for \nthe power to travel instantaneously, and synchronizes his watch with the\nstation clock, after accounting for the time for light to travel to his\nposition.\n\n13. From his distant position, at 12:00:00, he travels instantly to the\nmail car at the front of the train and attacks the mail agent, felling \nhim instantly. He then looks toward the rear of the train, and sees the \nother mail agent busy and distracted with the business of getting his \nmail bag ready to be snagged by a hook at the \"next\" station.\n\n14. The oppressed native instantly travels to the rear of the train, and \neven allowing for a couple of seconds of light lag, as he arrives, he \nsees the second mail agent is still getting his bag ready. The oppressed \nnative attacks and kills him, too.\n\n15. The victorious native exults for a while but then, fearing the train \nmay stop at this \"next\" station, travels instantly back to his original \nobersvation position.\n\n16. He arrives, unnoticed by \"another\" oppressed native who is intent on \na wristwatch and subsequently disappears in a puff of Molochian prayer.\n\n17. Puzzled but not knowing how to investigate the \"other\" native's \nappearance, the native enjoys a victory beverage while waiting for the \nlight of his triumph to arrive. He does a spittake when he sees himself \nattack the rear-end mail agent *before* the train reaches *this* \nstation, and then *later* sees the front-end agent slain just as the \nfront of the train emerges - in the reverse order of how he recalls the \nevents.\n\n\nMore clear?"
        },
        {
          "kind": "sig",
          "depth": 0,
          "text": "Jeff Wilson - jwilson at io.com\nComputational Intelligence Laboratory - Texas A&M Texarkana\n< http://www.tamut.edu/CIL >"
        }
      ]
    },
    {
      "message_id": "<14958D9D0EAF4C1D86844D72152FF323@jill>",
      "from": {
        "name": "Gerry Quinn",
        "address": "gerryq at indigo.ie"
      },
      "date": "2011-05-14T15:08:06+00:00",
      "subject": "(urth) relative time travel",
      "in_reply_to": "<4DCE1436.2090802@io.com>",
      "reply_link": "header",
      "blocks": [
        {
          "kind": "quote",
          "depth": 1,
          "text": "From: \"Jeff Wilson\" <jwilson at io.com>\n1. Each day, a train 600,000 km long (two light seconds) traveling north\nat 90% light speed pulls through a station 600,000 long without slowing."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "I'm not sure your figures are right here...\n\nIf these are the lengths observed by the native (as it appears), then the \nrest length of the train is more like 1,400,000 km.  The mail agents will \ntake this into account when discussing who acted first.  In their frame of \nreference the station is only 250,000 km long.  Logic will force them to \nconclude that the pickup happened first.\n\nLet's assume that they are going at only 86.7 % of c, so the time dilation \nfactor is only 2.  The train is 4 light seconds long.  The station is 2 \nlight seconds long, but they will observe it to have contracted to 1 light \nsecond long.  So they will expect that the pickup will happen about 3 \nseconds before the drop off (a little more in fact as they are going at less \nthan light speed, say 3.5 seconds)."
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "6. The mail agent at the front of the train sees the pickup happen, then\ndrop-off happen much later."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "He sees the drop-off happen 7.5 seconds after he does the pickup."
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "7.The mail agent at the rear of the train sees the drop-off happen, then\nthe pick-up happen a short time later."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "He sees the pickup happen 0.5 seconds after he does the drop-off."
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "11 The next day, the oppressed native calls on some pagan OT being for the \npower to travel instantaneously, and synchronizes his watch with the\nstation clock, after accounting for the time for light to travel to his\nposition.\n\n13. From his distant position, at 12:00:00, he travels instantly to the\nmail car at the front of the train and attacks the mail agent, felling him \ninstantly. He then looks toward the rear of the train, and sees the other \nmail agent busy and distracted with the business of getting his mail bag \nready to be snagged by a hook at the \"next\" station."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "Okay.  If he simply waited 7.5 seconds he would see the drop-off, but he \ndoesn't have time.  He briefly glances out the window and sees that the \nstation clock reads 11:59:59 (it's a light second further away compared to \nhis starting point), then he waits 0.2 seconds.  He observes that the clock \nnow reads 11:59:59.01 (he has travelled 0.18 light seconds further from the \nclock, and it is also running slowly in his frame of reference)."
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "14. The oppressed native instantly travels to the rear of the train, and \neven allowing for a couple of seconds of light lag, as he arrives, he sees \nthe second mail agent is still getting his bag ready. The oppressed native \nattacks and kills him, too."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "Okay.  While he waited 0.2 seconds at the front watching the clock, the \ntrain travelled 0.18 of a light second forward in the reference frame of the \nstation.  So from here the clock reads 11:59.59.19."
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "15. The victorious native exults for a while but then, fearing the train \nmay stop at this \"next\" station, travels instantly back to his original \nobersvation position.\n\n16. He arrives, unnoticed by \"another\" oppressed native who is intent on a \nwristwatch and subsequently disappears in a puff of Molochian prayer.\n\n17. Puzzled but not knowing how to investigate the \"other\" native's \nappearance, the native enjoys a victory beverage while waiting for the \nlight of his triumph to arrive. He does a spittake when he sees himself \nattack the rear-end mail agent *before* the train reaches *this* station, \nand then *later* sees the front-end agent slain just as the front of the \ntrain emerges - in the reverse order of how he recalls the events."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "He's not all that surprised.  He knows that the point where he killed the \nrear agent was 0.18 light seconds closer to him, so naturally he will see \nthat happen first.  He killed the agents at 12:00:00 and 12:00.00.1 \nrespectively, so the light from the second killing arrives 0.08 seconds \nbefore that from the first.\n\n- Gerry Quinn"
        }
      ]
    },
    {
      "message_id": "<4DCEF2A9.9090604@io.com>",
      "from": {
        "name": "Jeff Wilson",
        "address": "jwilson at io.com"
      },
      "date": "2011-05-14T21:22:49+00:00",
      "subject": "(urth) relative time travel",
      "in_reply_to": "<14958D9D0EAF4C1D86844D72152FF323@jill>",
      "reply_link": "header",
      "blocks": [
        {
          "kind": "quote",
          "depth": 1,
          "text": "On 5/14/2011 10:08 AM, Gerry Quinn wrote:\n\nFrom: \"Jeff Wilson\" <jwilson at io.com>\n1. Each day, a train 600,000 km long (two light seconds) traveling north\nat 90% light speed pulls through a station 600,000 long without slowing.\n\nI'm not sure your figures are right here...\n\nIf these are the lengths observed by the native (as it appears), then\nthe rest length of the train is more like 1,400,000 km. The mail agents\nwill take this into account when discussing who acted first. In their\nframe of reference the station is only 250,000 km long. Logic will force\nthem to conclude that the pickup happened first."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "ahem. \"You guys that already know this will see that I have abstracted \nnumerous distracting features out of this account.\"\n\nThis example is adapted from Richard Morris' TIME'S ARROWS\n\nhttp://www.amazon.com/Times-Arrows-Scientific-Attitudes-Toward/dp/0671617664/ref=sr_1_1?s=books&ie=UTF8&qid=1305407823&sr=1-1#reader_0671617664\n\nyou can search for \"lightning\" to find his version that dodges length \ncontraction by having no background and no definite dimensions.  I tried \nto include some of these to give the less accustomed posters fewer \nindefinite things to envision at once."
        },
        {
          "kind": "sig",
          "depth": 0,
          "text": "Jeff Wilson - jwilson at io.com\nComputational Intelligence Laboratory - Texas A&M Texarkana\n< http://www.tamut.edu/CIL >"
        }
      ]
    },
    {
      "message_id": "<D29380BAED694F0782E2FC49181B497B@jill>",
      "from": {
        "name": "Gerry Quinn",
        "address": "gerryq at indigo.ie"
      },
      "date": "2011-05-14T23:08:05+00:00",
      "subject": "(urth) relative time travel",
      "in_reply_to": "<4DCEF2A9.9090604@io.com>",
      "reply_link": "header",
      "blocks": [
        {
          "kind": "quote",
          "depth": 1,
          "text": "From: \"Jeff Wilson\" <jwilson at io.com>\nOn 5/14/2011 10:08 AM, Gerry Quinn wrote:"
        },
        {
          "kind": "quote",
          "depth": 2,
          "text": "From: \"Jeff Wilson\" <jwilson at io.com>"
        },
        {
          "kind": "quote",
          "depth": 3,
          "text": "1. Each day, a train 600,000 km long (two light seconds) traveling north\nat 90% light speed pulls through a station 600,000 long without slowing."
        },
        {
          "kind": "quote",
          "depth": 2,
          "text": "I'm not sure your figures are right here..."
        },
        {
          "kind": "quote",
          "depth": 1,
          "text": "ahem. \"You guys that already know this will see that I have abstracted \nnumerous distracting features out of this account.\"\n\nThis example is adapted from Richard Morris' TIME'S ARROWS\nhttp://www.amazon.com/Times-Arrows-Scientific-Attitudes-Toward/dp/0671617664/ref=sr_1_1?s=books&ie=UTF8&qid=1305407823&sr=1-1#reader_0671617664\nyou can search for \"lightning\" to find his version that dodges length \ncontraction by having no background and no definite dimensions.  I tried \nto include some of these to give the less accustomed posters fewer \nindefinite things to envision at once."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "I can search but it doesn't show me the pages.  That's beside the point, \nthough. Weren't you trying to show that travel via a wormhole is time \ntravel?  I don't think your illustration shows that.  In particular, you \nsay:\n\n\"16. He arrives, unnoticed by \"another\" oppressed native who is intent on\na wristwatch and subsequently disappears in a puff of Molochian prayer.\"\n\nNope.   He arrives after he left - in my example, 0.4 seconds after he left. \nHe doesn't ever meet himself.\n\nTo get time travel from instantaneous movement, you need a more complicated \nsituation AND certain assumptions involving the reification of some concepts \nfrom special relativity, which are not provable in our universe, and which \nwould certainly be false in a universe in which instantaneous travel was \npossible.\n\n- Gerry Quinn\n."
        }
      ]
    },
    {
      "message_id": "<4DCF27D7.9050201@io.com>",
      "from": {
        "name": "Jeff Wilson",
        "address": "jwilson at io.com"
      },
      "date": "2011-05-15T01:09:43+00:00",
      "subject": "(urth) relative time travel",
      "in_reply_to": "<D29380BAED694F0782E2FC49181B497B@jill>",
      "reply_link": "header",
      "blocks": [
        {
          "kind": "quote",
          "depth": 1,
          "text": "On 5/14/2011 6:08 PM, Gerry Quinn wrote:\nI can search but it doesn't show me the pages. That's beside the point,\nthough. Weren't you trying to show that travel via a wormhole is time\ntravel?"
        },
        {
          "kind": "text",
          "depth": 0,
          "text": "The wormhole example is much simpler. The negative curvature makes a \nbridge between two portions of space-time, and time progresses \nidentically as measured through the wormhole. Their subjective timelines \nremain connected one-for-one despite their relation to the objective, \nexternal universe's timeline.\n\nSo if the traveling terminus is accelerated such that it experiences a \none year trip while observers see it gone for two years, today's \ntraveling terminus is linked to the stationary terminus of a year ago, \nsince it has also experienced a year  apart."
        },
        {
          "kind": "sig",
          "depth": 0,
          "text": "Jeff Wilson - jwilson at io.com\nComputational Intelligence Laboratory - Texas A&M Texarkana\n< http://www.tamut.edu/CIL >"
        }
      ]
    }
  ]
}