Everyone can quote 'Burnside's Advice'...

"Friends Don't Let Friends Use Reactionless Drives In Their Universes"

... but tracking down the original and seeing it in context is proving impossible. Can anyone show where this famous quote originates?

  • Don't know, but it must post-date Larry Niven's Known Space books and stories (published over the late 1960s to 1990s), which is likely the source of the idea that such advice was needed.
    – Zeiss Ikon
    Commented Sep 20, 2017 at 16:00
  • Just did a good-effort Google; it appears Ken Burnside is a game designer, and is still alive -- may even have a Facebook page. Try messaging him?
    – Zeiss Ikon
    Commented Sep 20, 2017 at 16:10
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    You could twit at him; twitter.com/kenburnside1?lang=en
    – Valorum
    Commented Sep 20, 2017 at 16:21
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    @Valorum Thanks for that, if ever I take leave of my senses sufficient to twit at all I'll look him up.
    – Ash
    Commented Sep 20, 2017 at 17:28
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    The basic problem is that reactionless drives are so efficient that one can make a dirt-cheap planet-cracking missile by mounting one in the equivalent of a Naval row boat. Commented Sep 20, 2017 at 23:45

1 Answer 1


I'm the Ken Burnside in question.

It came up in response to a reoccuring discussion on SFCONSIM-L, a mailing list I moderate (and participated actively in at the time as I was developing Attack Vector: Tactical).

New List Member: "Hi, I'm writing about X, with spaceships that do multiple G thrusts, just like in the works of author Y!"

Ken (and other list members): "How do you keep someone from sterilizing planets as a result of putting that multiple G thrust on a cruise missile, launching it from the orbit of Saturn and letting it hit at fractions of c? The only way to really avoid this is using delta-v limited thrust and the rocket equation."

New List Member: "You big meany! I'm just trying to tell stories of rip-roaring adventure! If it's good enough for author Y, it's HARD SF!"

Ken: "Author Y made their reputation {30|40|50} years ago, and standards have changed. Besides, reaction drive calculations can be done fairly simply with a spreadsheet. You will end up with multi-month travel times, going onwards of two years, which may impact the story you want to tell."

New List Member: "AAARGH! You're ∗impossible!"∗

Ken: "Here's my advice: Friends don't let friends use reactionless drives in their universes."

This happened multiple times over four years, and Burnside's Advice became the shorthand form of the discussion. I'm still amused that this gets quoted more than 15 years later!

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    For what it is worth, I can vouch for the Ken Burnside who answered above. But do you trust me? I quote Ken in my website: projectrho.com/public_html/rocket/reactionlessdrive.php Commented Sep 21, 2017 at 3:34
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    Just replied on Twitter. Commented Sep 21, 2017 at 4:08
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    Ok, confirmation received. This is the real Ken Burnside people :). See also: i.sstatic.net/ifezW.jpg
    – Möoz
    Commented Sep 21, 2017 at 4:35
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    "I'm still amused that this gets quoted more than 15 years later!" Clarke's Law is three times that age, maybe more. Murphy (of Murphy's Law) was a real rocket scientist at White Sands in the 1940s, an acquaintance of G. Harry Stine. Burnside's advice will probably still be quoted when interplanetary travel, at least, is no longer SF.
    – Zeiss Ikon
    Commented Sep 21, 2017 at 15:52
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    @KenBurnside Do you know of a list with other technologies that break the way the world works in strange ways? I've read a couple of essays on travelling in time and space lately that seemly to alluded to a list of technologies that sound good until you look too close, your advice was quoted along with similar admonishments concerning time travel and inertial dampers.
    – Ash
    Commented Sep 27, 2017 at 21:58

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