Was it ever explained why and how was the planet from Star Trek TOS episode, "Miri", was an exact duplicate of Earth?

In my opinion this was the most interesting question in the episode and it was left unanswered.

  • 2
    That episode would have made sense in a series dealing with alternate histories (something like Sliders). Miri's planet duplicated both the continents and the history of Earth, up to the time of the plague accidentally caused by the life prolongation project, which was probably late in the planet's 20th century. "Bread and Circuses" was another such episode, with an earlier divergence; as I recall, that episode made a point that the planet's atmosphere and land/water ratio were identical to Earth's. In both cases, I think the point was to emphasize that Earth could have gone the same way. May 18, 2012 at 20:05
  • @KeithThompson: For what it's worth, the latter episode also made a point that it's a complete Earth duplicate, because the Romans speak English. Err ... Nov 28, 2016 at 23:22
  • When there's finite number of combinations of atoms in infinity universe, you are going to find multiple exact copies of everything. Sep 18, 2018 at 2:01
  • I remember the novelisation threw the concept out because it meant nothing to the rest of the episode and was daft to begin with.
    – IG_42
    Sep 18, 2018 at 11:25
  • @IG_42: Yes, to someone who has seen the episode many times, as early as a rerun in the 1960s (on too late to have seen it first run) it is extremely annoying to read the "exact duplicate" phrase because indeed they do nothing with that. If they had in some way utilized knowing that it was a duplicate -- also, if looked like it was an exact duplicate of 1960s' Earth, nothing futuristic about the buildings. I am sure everyone regretted this aspect of what otherwise was a superior and scary episode. It was almost like I am Legend, how scary for the kids esp,. because they transformed eventually.
    – releseabe
    Jan 16 at 6:31

6 Answers 6


I don't recall this being answered in the episode but there is a Star Trek reference book called The Worlds of the Federation, which indicates that not only the planet, but the entire solar system was an exact duplicate of the Sol system and was created by the Sol system passing through a temporal or spatial rift of some sort and being duplicated.

Another Star Trek reference book, Star Trek: Star Charts, indicates rather that the planet was a terraformed recreation produced by the Preservers and populated by other groups of people taken from Earth in the past as they did with the Native Americans in another episode of TOS. Both works indicate the natives called the planet Earth and the Star Charts book indicates the capital city before the plague was called New York.


Memory Alpha gives this explanation: Hodgkin's Law of Parallel Planetary Development

The theory was that similar planets with similar environments and similar populations tended to gravitate toward similar biological developments over time. Although initially applicable only to biology it was later expanded to include a tendency to move toward similar sociological developments as well with sentient beings.

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    Unfortunately, Hodgkin's Law shouldn't apply to landmasses' shapes, but it made it easier on the modelwork.
    – aramis
    Aug 5, 2011 at 6:25
  • And in the 1960's it was easier to sell and produce a story about a planet that was identical to Earth, rather than take the more symbolic route
    – SteveED
    May 19, 2012 at 15:26
  • No, but if by chance this planet ends up with similar landmasses the Hodgkin's Law should apply. Jan 15, 2018 at 5:42

In the DTI novel: Forgotten History by Christopher L. Bennett,, Miri's Earth was actually Earth itself, of an alternate timeline. Miri's Earth had briefly drifted into the main universe due to instability in the local sector of space. It later returned to its original timeline.

In the Preserver novel series by William Shatner, the planet was revealed to have been duplicated from Earth on a subatomic level by the Preservers.

Also in this novel series, there was a reference to duplicates of several other planets, "Starfleet managed to uncover at least three duplicate Earths, four duplicate Qo'noSs, two of Vulcan and one duplicate Andor. These worlds were kept highly classified by Starfleet for fear of the panic it would create to members of the United Federation of Planets. "

But as far as I know there has never been a in-episode expaination as to the how-&-why.


Well this is easy, and based on the assumption our universe is infinite. So if you have an infinite universe, then the odds are high that two or more solar systems may develop to look the same and even support the same type of life.

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    The Universe may or may not be infinite; the Galaxy certainly is not. Even assuming, say, a trillion M-class planets in the Galaxy (a vast overestimate), the odds against another one being that similar to Earth are beyond astronomical. May 18, 2012 at 19:48

The duplicate Earth was a result of the providers transplanting humans much as they did in this side of paradise. Unfortunately for the humans their idiocy went hand in hand with their wisdom. They most likely doomed themselves.


The preservers were mentioned in "paradise syndrome" (indian transplant). Two other duplicated earths were the miri planet and the roman planet. P.S. the paradise syndrome planet might have been ideal for the indians who called in picards debt...

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