{
  "export": {
    "source": "https://urth.darkrealm.vip/thread/whorl/571",
    "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": "whorl",
  "thread": {
    "id": 571,
    "subject": "stardrive",
    "messages": 1,
    "voices": 1,
    "first": "1998-11-03T17:30:00+00:00",
    "last": "1998-11-03T17:30:00+00:00"
  },
  "messages": [
    {
      "message_id": "<whorl-v0009-0037@digest.urth.net>",
      "from": {
        "name": "m.driussi",
        "address": "m.driussi at genie.com"
      },
      "date": "1998-11-03T17:30:00+00:00",
      "subject": "(whorl) stardrive",
      "in_reply_to": null,
      "reply_link": null,
      "blocks": [
        {
          "kind": "text",
          "depth": 0,
          "text": "Re: questions regarding the stardrive that is pushing the Whorl.\n\nBecause the details in the text are so very few, the entire topic is\nwildly speculative.\n\nBy my reading, at least, it appears that the Whorl had a cruising\nvelocity of .95 c, or ninety-five percent of light speed.  This\nresults in a time dilation factor of around 3:1, so that only one\nyear passes onboard for every three years that pass in the universe\nat large.\n\nTo current \"realistic\" stardrive thinking, .95 c is so high that it\nis effectively \"magic.\"  Even the most energetic of \"realistic\"\nrockets, a photon drive (thrust produced by the mutual annihilation\nof matter and antimatter) with a Mass Ratio of 16 (so a one ton ship\nuses 15 tons of reaction mass--in this case, 7.5 tons [!!] of antimatter\nand 7.5 tons of matter) can only go .88 c in a voyage where the ship\nmust come to a stop at the end (i.e., in a forever nonstop flyby this\nstardrive and Mass Ratio can maybe hit .9922 c).\n\nAn Ion Scoop, like that for the Bussard Ramjet (the great hope of the\n60s), while an excellent model for \"living off the land\" and thereby\navoiding those crushing Mass-Ratio figures, is currently thought to\nbe incapable of surviving (or attaining) velocities over around .2 c.\n\nSo we are left with fringe concept NAFAL (nearly as fast as light)\ndrives.  The following appropriate the ion scoop's \"living off the\nland\" function: Milton Rothman's wormhole jet (\"free\" photons\nsiphoned from nearby stars via wormhole); Clarke's quantum jet from\nSONGS OF DISTANT EARTH (perversely limited to .2 c anyway, due to\ninterstellar friction); the tachyon drive of Haldeman's THE FOREVER\nWAR (using tachyons as exhaust for NAFAL travel); and Sheffield's\nquantum jet from THE MCANDREW CHRONICLES.  There aren't enough\ndetails to say much about the quantum \"spin-ships\" of Dan Simmons's\nHYPERION, but they would seem to fall into this category; as would\nthe NAFAL ships of Le Guin's Hainish novels.\n\n(When dealing with these fringe concept drives, it occurs to me that\neven discounting Mass-Ratios, another barrier to cross is the fact\nthat a ship travelling at .95 c has its mass multiplied by 3.2!  So\nif your magic jet drive can push an asteroid up to .8 c [at which\npoint it is really pushing 1.667 times the rest mass of the\nasteroid], to attain .95 c will require that the same drive push\ntwice as much mass.  So even magic drives have consequences.)\n\n=mantis=\n\n*This is WHORL, for discussion of Gene Wolfe's Book of the Long Sun."
        }
      ]
    }
  ]
}