In the episode Ship in a Bottle, Professor James Moriarty wishes to leave the holodeck. The whole episode is centered around his complicated gambit to do just that, by giving the illusion to Picard that he already has. But in the beginning of the episode, they urgently implore him not to walk out of the holodeck.

PICARD: You must believe me, Professor. If you step outside that door, you will cease to exist.

Later in the episode, Barclay, Geordi, Data, and Picard brainstorm ways to transport Moriarty's love Regina out of the holodeck, but they are very cautious about it and don't want to try anything on her until they've thoroughly tested it on other objects, presumably because of the risk that she too could "cease to exist."

But why? Why wouldn't there be multitudinous backups of James and Regina in holodeck memory? Just as "ending a program" saves the program to memory, why wouldn't a holodeck character walking out of the holodeck cause him to "disappear" while still "existing" in memory?

This is a different (though related) question from Why can some holodeck matter leave the holodeck, while other holodeck matter (notably people) cannot? Reading both questions (and their respective answers) in full makes this quite clear. My question is, "Why wouldn't Moriarty's program continue to be saved in memory if he tried leaving the holodeck?" Though the other question uses Moriarty as an example, it can be generalized as, "Why can't holographic people leave the holodeck when some objects created in it can leave?" Both questions are about the mechanics of the holodeck, both are about what happens when certain holodeck objects try to leave, but they are ultimately about different things and have different answers as a result.

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    Pure conjecture, but my guess is that the holodeck has some sort of aggressive garbage collection bug that clears dangling pointers from permanent storage at the same time as it clears up the RAM. Commented Apr 6, 2015 at 22:47
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    Don't they spend half that episode marveling at the fact that the Holodeck has created a real, sentient being? I always understood that the fear was that if they kill this Moriarty, the one they re-create from a backup might not have that same inexplicable spark of life.
    – Nerrolken
    Commented Apr 6, 2015 at 22:54
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  • @Erik and close voters, I have edited to explain the differences between the two questions. Commented Mar 11, 2017 at 14:38

3 Answers 3


According to Voyager’s Message in a Bottle episode, holodeck technology works so that the data of the program object is embedded in the object. So the program contains its one and only instance.

To use an analogy of RAM memory, holograms reside either in RAM or in storage. They cannot be in both.

Why this is was never explained. I don't remember exactly, but wasn't the holodeck an acquired technology, not developed?

  • When was this limitation described? Commented Apr 7, 2015 at 9:31
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    "Voy: Message in a bottle" - EMH is sent with a message as a holographic data stream through a wormhole. they didn't copy him - they moved his whole program to another ship. "Voy: Living Witness" would seem to contradict it, however, as well as Vic Fontaine hologram (somewhat, since his program was ran continuously so as to preserve the evolvement and for best results of the program).
    – AcePL
    Commented Apr 7, 2015 at 10:14
  • Thanks. I'm gonna watch that episode later to judge for myself. Commented Apr 7, 2015 at 18:09
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    @AcePL You're forgetting artificial gravity in a dedicated holodeck. You only really need enough room for each real person to be able to move their arms and legs without hitting anybody else. All movement can be simulated with gravity changes and moving surfaces and each person can be given their own little "perspective bubble". Takes more computer power, but not much more since the bulk of the simulation is already done.
    – Perkins
    Commented Oct 3, 2015 at 0:13
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    Our Man Bashir is further evidence of the one-copy thing. He had to avoid any character deaths because the holodeck would erase their physical patterns.
    – Izkata
    Commented May 25, 2016 at 3:40

While they could certainly create "a new Moriarty", there is actually no guarantee that that one will also be sentient.

Think of it like this:

You have a recipe for apple pie, which you decide to make. While making your pie, somebody else adds a secret ingredient and you have no idea what it was. Now you have an apple pie that, once it's gone, you have no idea on how to recreate.

A similar thing happens with Moriarty. They have no idea how Moriarty became sentient, so if they "lose" this one, the next one might not be...well... as tasty an apple pie.

  • Just out of curiosity, how do they tell a sentient Moriarty from a non-sentient one?
    – user14111
    Commented Apr 7, 2015 at 9:40
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    I guess you ask them to do something outside of their normal programming? I'm not too certain what they consider the difference between a sentient and a non-sentient one, but clearly they seem to somehow feel that this hologram is sentient where normal ones are not.
    – Theik
    Commented Apr 7, 2015 at 9:45
  • Simple question: who are you? Vic Fontaine replies: proprietor of this establishment and a hologram. So he's sentient because he knows what he is. Sentiency does not imply free will or other attributes of living sentient being.
    – AcePL
    Commented Apr 8, 2015 at 9:56
  • Can't they just go back and make the same identical request as before: to create an opponent who can defeat Data? ;-)
    – Andy
    Commented Dec 21, 2022 at 17:46

Interestingly, this was discussed in an earlier draft of the screenplay for TNG: Elementary, Dear Data. In short, Data and Picard are convinced that had Moriarty left the holodeck, he would have survived. No specific explanation is given for this belief other than that the paper (with the drawing of the Enterprise on it) survived outside the holodeck.

DATA: Right up to the end, he never knew.

PICARD: No. He didn't.

PULASKI: Know. Know what?

PICARD: That he could leave the Holodeck.

PULASKI: But that's not possible.

DATA: I do not know how, but for Moriarty it was.


PULASKI: But how do you know he could leave the Holodeck?


Data reaches into his coat pocket and removes the paper on which Moriarty first drew the sketch of the Enterprise.

PULASKI: The drawing?

DATA: No. The paper. This piece of paper was created as part of the Holodeck illusion. If it could leave the Holodeck, so too could Moriarty.

I think we can safely assume that someone from the continuity department drew a great big red line through this scene before filming started.

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    While this is a great find in terms of a related anecdote, hinting at the continuity department having made sure that in fact, it should be impossible, this does not really answer the question why it is impossible, does it? Commented Oct 26, 2018 at 9:58
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    @PhilipKlöcking - In the early episodes there was a lot of 'early installment weirdness' before the continuity team established that small items were made by the replicator and large items were made using holograms and forcefields. This seems to be a case where the writer didn't get the message.
    – Valorum
    Commented Oct 26, 2018 at 11:32
  • Does this mean that, at least within this draft, Picard was lying/mistaken when he gave Moriarty the "cease to exist" line? Or was the line different? Or something else? Commented Oct 27, 2018 at 23:25

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