Holodeck and Computers FAQ

Last modified: Wednesday, 23 February 2005 10:06 PM -0800
Maintained by: Joshua Bell, inexorabletash@gmail.com
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  1. How real is real? - Mechanics of the Holodeck
  2. Where does it all end? - The Holodeck and troublemakers
  3. What if...? - Limitations and possibilities of the Holodeck
  4. Holodoc - Voyager's Holodeck technology
  5. Will it run Windows? - The Enterprise computers
  6. Credits
  7. References

1. How real is real?

"How does it work?"

A Holodeck can create simulations in the following ways:

Note that the wall/hologram/force beam simulations are easy for the holodeck to carry out, and that the hologram/force beam/replicator simulations were possible during "Encounter at Farpoint" (when Wesley got soaked).

It is possible, however, that the Holodeck-matter simulations, were not possible before the upgrades made by the Bynars in "11001001" [TNG]. This would explain Riker's surprise at the realism of the Minuet simulation.

Also, if an object's status changes the simulation type will change seamlessly as well. For example, someone sees a distant tree (walls), approaches it (hologram), leans on it (force beams), breaks off a branch (Holodeck-matter), then picks and eats an apple (replicated).


"What about eating on the Holodeck? Does Troi do it to keep thin with all that chocolate she eats?"

Any food consumed on the Holodeck would be replicated. If it were any of the other types of simulation, it would dissociate or evaporate when you left the holodeck, which doesn't sound at all pleasant.


"What is this 'meat puppet' description I've heard used?"

A 'meat puppet' is a old term resurrected to describe a replicated humanoid form created on the Holodeck, and dragged around by force beams. If the force beams failed, you'd be left with a limp, lifeless body.

(This dates back to before we'd ever heard of Holodeck-matter. Creative, weren't we?)


"So can you take things off of the Holodeck?"

Yes. Any object replicated on the Holodeck may leave. Unfortunately, it is sometimes hard to tell what is replicated, and what is not. Snow, such as the snowball thrown by Wesley in "The Naked Now" is easily replicated, and dampness is hard to simulate. The book thrown by Picard in "Ship In A Bottle" [TNG] would be easily simulated by force beams and thus was not replicated.

The paper in "Elementary, Dear Data" [TNG] was likely simulated until the computer realized that it was going to be carried off the Holodeck, at which point it would have been seamlessly replaced with a replicated copy.


"Didn't Picard lie to Moriarty (in "Elementary, Dear Data" [TNG])?"

According to various reliable sources, that was Gene Roddenberry's intention. If the paper could have left, Moriarty should have been able to, goes the logic. Fortunately, this scene was cut, and as always, canon is what we see on the screen, big or small. This means the whole argument against replicating people holds - that the computer cannot store that much information.


"What about beaming things off the Holodeck (ala "Ship In A Bottle" [TNG])?"

This has never been tried, as explained in the episode, which is why the computer was unable to simulate the results. Replicated objects should be able to be transported out of the Holodeck, but anything relying on the force beams would instantly collapse.

As for uncoupling the Heisenberg Compensators - that would give a random quantum state to each particle in the transported object. It would be akin to a molecular-resolution transport - probably deadly for any living being.


"Now wait a second. How come something simple like the chair in "Ship In A Bottle" [TNG] wasn't replicated?"

They were testing beaming something composed of the 5th type of simulation; an object made of Holodeck matter, just like Moriarty and the Countess. Obviously a purely replicated chair wouldn't do for this experiment, so Geordi probably tweaked the chair to be the right kind of simulation to use for the test.


"What's this about 'HoloSex'?"

If current trends are a pattern for the future to follow, then Virtual Reality Sex will be alive and well long into the 24th century. Quark's bar on DS9 has personal holosuites on the second floor. Various stimulating programs are available.

In "The Perfect Mate" [TNG], Riker manages to croak out something about "I'll be in Holodeck 4..." after an encounter with the metamorph. No proof that he did anything, true. Minuet (in "11001001" [TNG]) was "As real as you need me to be." Uh-huh. Geordi doesn't seem to have much luck off the 'deck, it seems, nor does Reginald Barclay.

Zek in "The Nagus" [DS9] certainly enjoys those holosuites!

Draw what conclusions you will.


"What if you urinate/defecate/excrete whatever on the Holodeck?"

One would hope the Holodeck is smart enough to clean up after you. It probably gets transmuted into some form the bulk matter stores can use, and saved for later use by replicators or the Holodeck again. The ultimate in recycling.

And, er, if another real person in the Holodeck is the... recipient of your, er, donation? The Holodeck doesn't interfere, and we have that little charmer, Alexander, to prove it. (Thanks to Benjamin Chee for pointing this one out.)


"Can you get hurt on the Holodeck?"

Yes. Even when it isn't malfunctioning, the simulation can't protect you from your own stupidity. Broken ribs and arms from cliff diving and other sports practiced on the Holodeck are often seen treated in Sick Bay.


"But the replicators can't even make unhealthy food!"

Replicators can (within limits of technology and energy) produce anything for which they have a pattern. Certain objects may need security clearance. But you can have the replicator make a glass of water, and use the glass as a weapon - it may be smart, but it's not foolproof.


"What happened to the "arch" they used in the first season?"

Its intended use was as a way to program the Holodeck and access the ship's computer, as well as a virtual reality "safeword". In later episodes, they just used the "exit" and programmed the computer by voice. It is still around, recently seen in "Ship In A Bottle" [TNG]. The arch was how Moriarty first learned that he was a simulation, and gained control of the ship in "Elementary, Dear Data" [TNG], and it was seen in Star Trek: Generations as well.

2. Where does it all end?

"How do they manage to keep walking for hours and hours?"

The Holodeck has a force field treadmill. If its occupants get too close to the walls, they are shifted away. Since the Holodeck can modify its gravity in 3 dimensions, the occupants won't notice any inertial change. The novel "Reunion" [TNG] (while non-canon) goes into details about this.


"But what about the walls seen in "Encounter at Farpoint" [TNG] and "Ship In A Bottle" [TNG], demonstrated by Data?"

In "Encounter at Farpoint" [TNG], Data threw a Holodeck-generated rock at the wall. There are a few possibilities. Either the computer realized the intent of the demonstration, and didn't replace the rock with an image on the Holodeck wall; or the "simple pattern" of that simulation didn't allow for treadmill-scrolling; or the Holodeck computer wasn't quite powerful enough, pre-Bynar intervention.

In "Ship In A Bottle" [TNG], Data throws his own communicator at the wall. The Holodeck must have safeguards not to summarily destroy things it didn't create, so it didn't do anything to affect the communicator.


"What happens if two real people enter a Holodeck and start running away from each other?"

The simplest answer is that the Holodeck "compartmentalizes", in effect becoming a separate Holodeck for each person within it. In reality, the two people would probably be only a few meters apart, but would be separated by a Holodeck-projected "wall". If they turned to look at each other, they would see an image of the other projected on that wall.

Benjamin Chee points out that Star Trek: Generations strongly supports this notion; whilst on the simulation of the seagoing Enterprise, Picard calls for the Holodeck arch and it appears on the ship's deck. But earlier, Worf and Crusher were sent overboard, below the level of the ship's deck and therefore below the floor of the Holodeck, unless the holodeck does compartmentalize to some degree.


"What if they take a real rock in with them, walk away from each other (past the physical limits of the Holodeck) and then toss the rock back and forth?"

This one is too easy. The holodeck could treat the rock in just the same way as it would treat a person. When it leaves the hand of the thrower, the Holodeck "wraps" it in its own miniature simulation, and hides it from the two people, who (in their own mini-Holodeck) see only an image of the rock. The rock is then moved (with force beams) from the thrower to the catcher, given the appropriate kinetic energy along the way. From the rock's point of view nothing out of the ordinary happens.


"So what if two people take a long rope, and start walking away from each other?"

The answer in this instance could be that the Holodeck hides part of the rope, and projects an image of a tightening rope along with force beam-generated tension.

In general, though, the answer to these "boggle the Holodeck" questions is that no, it's not perfect. You will encounter limitations to the technology, and gaps in the 'reality' will become apparent. However, you really do have to be looking for problems to find them, such as the left-right reversal in "Ship In A Bottle" [TNG]. (Benjamin Chee)

3. What if...?

"Can you go swimming on the Holodeck?"

Yes. Cliff diving has been mentioned as a recreation sport aboard the Holodeck (in "Conundrum" [TNG]), as has kayaking ("Transfigurations" [TNG]). Worf and Beverly also take a dip in Star Trek: Generations.

"So does it replicate all of that water?"

Probably not. What would likely happen is that a "personal space" of water would be replicated around the person, and the rest of the water in the pool, river, etc, would be a visual and auditory simulation. There is no canon evidence one way or the other, however, although in "Encounter at Farpoint" [TNG], there was enough real water present to soak Wesley.

"So what if someone is scuba diving, and the Holodeck door opens?"

Very likely, the force beams would give the sensation of a water surface over the doorway. Depending on the simulation, it might be possible for someone to wander onto a Holodeck, in normal duty uniform, and walk around someone who is swimming several meters below the "surface" of the pool. Only the swimmer would feel the sensation of water around them. Again, no canonical evidence either way.


"How about a Holodeck within the Holodeck?"

This is done in "Ship In A Bottle" [TNG]. They end up with a Holodeck (in which Picard was in control, and sent Moriarty away) inside a Holodeck (the real one, in which Moriarty took control) by the end of the episode. Is there a limit? Probably. No evidence for what that limit might be.


"Can you get the Holodeck to simulate someone?"

Yes. Although done numerous times, including "Ship In A Bottle" [TNG] and "A Matter of Perspective" [TNG], and "The Siege" [DS9]; "Hollow Pursuits" [TNG] is the prime example of this, and brings up the question...

"Is it ethical to simulate someone without their permission?"

Systems of ethics are by no means universal across cultural lines. Nor can we extend our 20th century foibles to the 24th century, where such things may be common place. In every instance, however, people thusly simulated have reacted negatively when they find out - for example, Troi, Riker, and Picard in "Hollow Pursuits" [TNG] and Dr. Leah Brahms in "Booby Trap" [TNG] and "Galaxy's Child" [TNG].

"So does the computer stop these simulations?"

Nope. Moriarty was able to do it in "Ship In A Bottle" [TNG], without any special permissions. It is amusing, however, to watch the episode again, and see how the simulated characters appear slightly stiff.


"Could you simulate the Enterprise bridge from the Holodeck, and use it to take over?"

The simulation would not be a problem - the Enterprise computer has extensive files of all Federation starship layouts, as shown in "Relics" [TNG].

In three episodes, the Enterprise has been controlled from the Holodeck - by Barclay in "The Nth Degree" [TNG], with a neural interface; in "Elementary, Dear Data" [TNG], where Moriarty somehow cracked the security codes via the Holodeck Arch; and in "Ship In A Bottle" [TNG], where Picard inadvertently gave Moriarty the security codes.


"Why not just have single-person Holodecks? For interaction, the computer could just link them all together!"

According to the TNG Tech Manual, there are four primary Holodecks and a number of personal ones. They could indeed be linked, but part of the fun of a Holodeck is the interaction with other people, knowing that they are real.

These do exist on Deep Space 9 in Quark's Bar, and are called holosuites. Some are quite small ("A Man Alone" [DS9]), others large enough for a number of people ("Blood Oath" [DS9]).


"Why do people get dressed up before going to the Holodeck? Can't it provide the period costumes?"

Yes. In First Contact Picard has clothing simulations created for himself and Lilly. But for the most part, the crew probably wants to get "into character" before entering the simulation.


"How do you fit two entire baseball teams (real people, not holographic extras) into one of Quark's Holosuites?" "Take Me Out To The Holosuite" [DS9]

We do know that Quark's holosuites come in various sizes. If you're talking about at least 18 people, each would require almost 4 square meters of area, or 72 square meters - and that's conservative. Imagine they all start walking out the door in single file - the computer has to shuffle each player's compartment around so that they end up by the door in the order they decide to leave! (In the episode, we never see a mass entrance or exodus, so it's possible that the holosuite does have some limitations). That's about a 9 meter by 9 meter space - a full sized holodeck by any account. But then again, there's no evidence that Quark doesn't have something of that size tucked in the back - for use only by clients with sufficient Latinum, of course.

The poster who asked this question on the newsgroup (Marco Antonio Checa Funcke) after seeing the preview for the episode proposed that perhaps the docked Vulcan starship's holodeck was used. Michael Welch answers that they definitely did not use the Vulcan ship because at the beginning of the episode, the Vulcan captain tells Sisko he needs to schedule holosuite use and Sisko refers him to Quark. The Vulcan captain at that point tells Sisko that it's a baseball program he's developed.


"Wasn't there a Holodeck on the original Enterprise? I'm sure I remember...."

Not in TOS. However, in "The Practical Joker" [TAS] the recreation deck had an environment simulator that used holograms and "stock" effects to produce an effect similar to the Holodeck, but not as realistic or convincing. The in that episode the computer malfunctions, trapping Uhura, Sulu and McCoy in a series of hostile environments.

This is probably what most people remember, and also the inspiration for the Holodeck itself on TNG.

Sources like "Mr. Scott's Guide to the Enterprise" mention similar things, including rooms with hologram projectors for the walls alone, but no canonical evidence exits.

4. Holodoc - Voyager's Holodeck technology

"Phage" [VOY] describes Voyager's medical holographic technology in explicit detail. Unfortunately, I missed the episode. I'm indebted to Allen G. Newman who wrote most of the following as an article in rec.arts.startrek.tech:

Voyager's explanation is actually the best yet; it works the best for explaining all the old questions about holo-matter from TNG. Apparently, matter on the Holodeck has the potential to be as detailed as real matter down to the level of molecular resolution. Instead of being composed of molecules, full-resolution holo-objects are composed of molecule-sized magnetic bubbles which can be individually manipulated through three dimensions by the computer.

The fact that the movement of individual holo-molecules can be controlled is of vital importance to the holo-lung being able to work. Replicators cannot create living matter because it is beyond the ability of the computer to "jump-start" all the necessary electron shell activity and atomic motions that determine biochemical activity (movement and transformation of molecules through the system). This limitation is irrelevant to the simulation of a lifeform on the Holodeck, though; since the Holodeck can move, reshape, create and destroy the magnetic-bubble molecules at will, there is no need to worry about the subatomic physics that make biochemistry happen on its own in real life-forms.

Even so, simulating even relatively simple lifeforms (such as humanoid lungs) stretches the capabilities of the system to the limit. Neelix had to be held motionless because it was beyond the ability of the computer to dynamically reorient such a complex, high-resolution construct. This same limitation makes it currently impossible to do something as incredible as having the Holodeck reanimate the complete transporter pattern of a person who had died, which could theoretically allow a person a kind of immortality within a Holodeck's simulated confines. (An afterlife in which a person could forever live in whatever environment the person chose, while still interacting with real people and objects visiting the Holodeck may become possible with exponential advances in computer processing.)

Note that holo-matter only has the potential to be detailed down to the molecular level. In most cases, the computer would have an easier time by using much larger magnetic bubbles that merely simulated surfaces and textures that can be seen and felt by people in everyday interactions. The image of the holo-doctor is almost certainly just an empty shell because there's no reason to waste computer power simulating the workings of internal organs.

Allen makes the assumption that Voyager's sick-bay holographic system works the same way as the main Holodeck on board Voyager, and that this is the same again as the Enterprise's Holodecks. On the other hand, I think the system has just evolved over time, and that Voyager's sick bay is using the latest and greatest technology.


"Why are they being so liberal with the Holodeck on Voyager? Aren't they short on energy?"

In "Parallax" [VOY] it is mentioned that the crew tried to hook the Holodeck power systems to the main power systems of Voyager and blew out a conduit due to incompatibilities. The Holodeck having its own power source may not make much sense, but at least the production crew justified the crew's use of it.

5. Will it run Windows?

"So tell me about the computers."

According to the TNG TM, the Enterprise has three main computers. Two reside in the Primary Hull (the saucer); they are vertical cylinders, about 8 decks high, and located on opposite sides of the saucer, flanking the bridge. The third computer is located in the Secondary Hull (engineering), and is smaller than the other two cores; it controls the Stardrive section when the ship separates.

We've seen the computer cores a number of times. In "Evolution" [TNG] the nanites were attacked in the computer cores. The set is probably meant to be just one deck of the multi-deck computer core, with the room seen the hollow central portion.

The computers are networked with each other, and with the rest of the ship via the ODN - the Optical Data Network. The ODN has enough processing power on its own to take over limited control of the ship in case of a complete computer failure.


"Why do the displays and touch pads work when the computers are down?"

The displays use "nanoprocessors" - cell sized mechanical computers - to display information. The display itself contains data polled from the ODN, and based on user selections, displays whatever is appropriate. So even if the computers go down, whatever information is (1) already on the ODN (or ODN backups) or (2) in the display itself can be selected and displayed.


"Why aren't the computers distributed?"

The three main computer cores are equipped with low level subspace field generators. This allows signal propagation within the cores at Faster-Than-Light (FTL) speeds, allowing the computers to perform much faster than anything constructable given 20th century technology, even theoretically. This cannot be applied (by 24th century technology) to smaller computers.

Once again, the ODN has enough distributed computational power on its own to run the ship, if all the cores are rendered inoperable. So the redundancy is there; look at how often on the show the computers are inaccessible, yet the ship can still be controlled. Also, all of the consoles are also operating independently. They have nanoprocessors and are always receiving a flood of data from the network, and interpreting and displaying it as the user wants it. So the computation as we think of it is distributed. Think of it as using a workstation farm for interfaces and data visualization, while running big jobs on a few networked Crays.


"Why the redundancy in the primary hull? Shouldn't the cores be in the secondary hull?"

We're not sure. The TNG Blueprints have the secondary hull computer core to one side of the ship centerline, and an equal-sized ballast space on the other. Galaxy-class ships do appear to be designed by committee, so maybe it was just cost.


"How big is a kiloquad?"

This hasn't been answered, and in the Encyclopedia, it says:

No, we don't know how many bytes are in a kiloquad. We don't even want to know. The reason the term was invented was specifically to avoid describing the data capacity of Star Trek's computers in 20th-century terms. It was feared ... that any such attempt would look foolish in just a few years, given the current rate of progress in that field.

However, many r.a.st.tech contributors have converged on kiloquad to mean 1000 (kilo) * 1 quadrillion bytes (or bits, but we'll stick with bytes for the explanation), the premise being that the phrase "quad" came into use instead of "pet" for Petabyte, since that sounds dumb. Then the kilo-, Mega- and Giga- prefixes were recycled.

Depending on where you live, a quadrillion is either 10^15 (American definition) or 10^24 (European definition). If Americans came up with this definition, that makes a kiloquad 10^18 bytes, which is around 2^60 bytes, which is about a billion gigabytes. If a European came up with this definition, we're talking about 2^90 bytes, which is a trillion gigabytes. Either way, we're talking a lot of bits.

Is this technologically feasible, given that an isolinear chip, quoted at 2.15 kiloquad in the TNG TM is about the size of a microscope slide?

From H. Peter Anvin:

...The 2.15 kqd isolinear chips [would have] a bit density of 2.94e+15 bits/mm^3 (I have assumed the dimensions to be 90x30x2.5 mm, this is probably on the high side if you exclude the part where you handle the chip); that means each bit could form a cube 7.0 nm (70 [angstrom]) to the side. The chips are optical, which I assume means they are read and written with electromagnetic radiation that behaves somewhat approximately like light. 7 nm is in the far ultraviolet region-near X-ray region (visible light ends at about 200 nm) which is really pushing the limit. Assuming some form of multi-state encoding that may exist may push this down to near UV which would then be a bit more practical to deal with, and more "optical", but that is irrelevant.

Hence, what we "know" about ST computer technology seems to correlate pretty well to the definition 1 quad = 1 quadrillion [American] bytes. It may be bits or bytes (it is only a factor of 8, obviously... it changes 7 nm to 14 nm if it is bits not bytes), but it seems to fit pretty well.


"But a quad is a unit of energy!"

Words can have more than one meaning.


"In "The Nth Degree" [TNG] when Barclay was taking over the core, why not just disconnect that core and use one of the other two?"

I can't remember the details, but presumably he took over the entire ODN as well. He'd have to in order to run the ship through the Holodeck (which have, BTW, their own almost-distinct computers (c.f. "Emergence" [TNG])).

6. Credits:

7. References:

See the Reading List FAQ for more details on the reference volumes mentioned above and below.

The question of "what is canon" has been argued for years in the Star Trek newsgroup hierarchy. In the realm of technical discussions, this can be refined to the question of "what evidence is factual, and what is apocryphal". These FAQs follow the currently dominant notion that "canon" is aired live-action material and nothing more, with the caveat that materials produced off-camera by the production crew are often (but not always) reliable predictors of the direction future canonical material will follow, and are therefore granted a special "quasi-canonical" status. Any other material falls into the realm of speculation - it may be perfectly well grounded speculation useful for building up technical arguments, or wild flights of fancy that have no rational basis.

In addition, more recently presented information is considered to supercede old information, unless the weight of the evidence supports the original data. While this may seem highly biased and may be eyed with some skepticism as a form of Orwellian "newthink", it is a more useful predictor of what those directly responsible for the creation of the series are likely to include as canonical material in the future.

For example, the excellent and groundbreaking Star Fleet Technical Manual, by Franz Joseph created in the 1970's was a very well thought out look at the technical world of Starfleet just slightly beyond what was seen in the original series. Unfortunately, and perhaps for purely arbitrary reasons, the future development of "canon" Star Trek diverged from this speculation. This in no way implies that there was anything wrong with that volume or any others, merely that due to later "evidence", it can no longer be regarded as an authoritative overview of Trek technology. On the other hand, the author performed a lot of research to create it, and therefore its speculation should not be dismissed out of hand.

That said, we are dealing with a universe in the process of being created by scores of (usually) non-technical people, aiming to provide weekly entertainment for a mass audience. There are many inconsistencies even amid the canonical material, and often times the wildest speculation on the newsgroup makes more sense than what we see in the episodes.

Canonical material:

Quasi-canonical material:

Highly regarded, but non-canonical material:

Joshua Bell, inexorabletash@gmail.com