A fundamental law of physics is, in short, that two things cannot exist in the same space at the same time. This is easily demonstrated by dropping a relatively large mass, such as pasta noodles, into a container of water, such as a pot. The water level will rise as it "makes room" for the pasta, and will overflow if you've put in too much of either. Conversely, if you were to scoop all of the noodles out (presuming you had a way to scoop just the noodles, without taking along any water at all) you would see the water sink down to its original level (or lower, if it had overflown earlier).

Taking this into consideration, I see a problem with transporter technology which I'm not sure I've ever seen addressed: What happens to the air surrounding a transport subject's origin point, or occupying the destination?

The transporter must have some means of compensating for the displacement, otherwise each transport should in theory be accompanied by a loud pop at each end - at the origin when the air collapses to fill a vacuum left behind, and at the destination when a relatively large volume of air is forced away to make room for the subject. This effect should be even more pronounced, and perhaps even hazardous, in closed environments such as spacecraft where the air has really no place to go.

One option would be to have the transporter exchange the air (or other matter, such as dust or raindrops) at the destination for the matter of the subject, as it is being transported. However, this is not seen as we would often notice small portions of dust storms or downpours getting dropped onto the transporter pad when people are transported into adverse weather conditions. Imagine having that cleanup as part of the Transporter Chief's job duties.

Another option would be to process the matter from the destination through the replicator, so that it is congruous with the same volume of air at the origin. This would be a fairly complex operation though, and could result in a lag too long to be acceptable by the laws of physics.

Come to think of it, this same (or a similar) issue should affect replicator and holodeck technology as well. Has any of this ever been addressed canonically, either in a Star Trek episode or in technical manuals?

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    Your first sentence is only partially correct and applies to fermions. "Things" is a bit vague. For example, photons can pass right through each other and can in a manner of speaking occupy the same space.
    – bitmask
    Aug 27, 2012 at 15:34
  • 3
    @bitmask Sure, but in the end we're talking about regular old solid (or liquid, or gas) matter for this case. Stuff's gotta move.
    – Iszi
    Aug 27, 2012 at 16:09
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    I believe in Star Trek lore, the "transported" material is assembled somehow from the atoms at the target site. It is just re-arranging what is already there. So, when displacing air, the air simply moves somewhere else. Consider that air is easily compressed to at least small degrees. Aug 27, 2012 at 16:20
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    Are we really supposing a species that can move matter from between two locations doesn't have a means for ensuring annoying sudden vacuums cannot be compensated for during a transport event? Perhaps the energy build-up to transport is preparing the receiving region by moving errant molecules out of the way, or out of phase or simply holding them still until the transport is complete. The scale of the technology simply overwhelms the nature of the problem. The transporter is one of the most advanced technologies in SF. I think they can handle some errant air/vacuum/other environmental medium. Aug 27, 2012 at 17:38
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    @Iszi Why does it have to be "instantaneous". If the arranging takes, say... a second, then this is no longer a problem. Aug 27, 2012 at 17:38

4 Answers 4


First, transports take 2-3 seconds to complete dematerialization, and a few more for materialization. We wouldn't see the crew fade in/out during the glowy parts otherwise.

Second, there's this quote from Star Trek: Enterprise 1x04, Strange New World:

Reed: "There's a problem, sir. There's contaminants in the matter stream. The phase discriminator can't seem to isolate the debris.. Reed to sick bay - medical emergency."

An Enterprise crewmember with leaves, ricks, and sticks embedded in their skin

So, explanation based on these two data points?

  • At the beam-out point, the dematerialization takes long enough that no vacuum is actually created. Think of a deflating balloon.
  • At the beam-in point, rematerialization simply pushes the atmosphere aside.
  • At both beam-in and beam-out points, a breeze that light (half a body width in 2 seconds) probably wouldn't even be felt by someone a yard/meter away.
    • Even if it were, we could even say that the transporter assembles the transportees in such a way that the breeze is funnelled upwards. Just an out-there guess, though.

The same should hold for replicators - when shown onscreen, they're shown having a materialization time period, just like transporter rematerialization.

Holodecks I'm uncertain about, but there's no reason the inside of a hologram has to be filled. They could be paper-thin - there's next to no displacement in that case!

  • 2
    I know this is very very old, but its worth noting that in TOS there are a lot of instant transports by aliens, all of them make a 'bong/bang' sound. Instant transport makes a sound that is very close to a bang which supports your answer. The slower speed does seem to push the air aside and so no sudden noise
    – Matt
    Oct 6, 2019 at 23:06
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    Could pushing the atmosphere aside be one function of the "annular confinement beam" (ACB) mentioned in the TNG Technical Manual? P. 103 says after dematerialization the transporter will "transmit the matter stream within an annular confinement beam to the transport destination", and the timeline on p. 107 indicates the ACB is transmitted to the target coordinates and must reach full power before the system initiates "transmission of matter stream through ACB". P. 108 also mentions that if the ACB is disengaged, "transport subject will form in a random fashion", like "dissociated gases".
    – Hypnosifl
    Jul 21, 2020 at 22:12
  • @Hypnosifl Possibly, but that sounds more like guiding to destination rather than handling the destination itself (like the purpose of the laser in this weapon)
    – Izkata
    Jul 22, 2020 at 14:13

Short Answer

Air particles would be moved out of the way as the new body is being constructed.

Complete Answer

I spent a long time, and I do mean a LONG time thinking this over and reviewing information in the Star Trek: The Next Generation Writers' Technical Manual, Fourth Season Edition. And I keep coming back to the points I've brought up in another question. While that provides support, it's not a full answer. I'm going to include some of that answer here as explanation.

I'm going to my source for this, one I've cited here before, the Star Trek: The Next Generation Writers' Technical Manual, Fourth Season Edition. This was sent to me directly, in a pitch package by the ST:TNG Script Supervisor Lolita Fatjo, when I was invited in to pitch story ideas to the producers. This is one of the Writers' Guides sent to those who would be writing for the show and, in some ways, goes beyond canon because it defines canon. In other words, it tells the writers what they can and cannot do on screen.

On page 28, under The Transporter - Once and for All:

... The stream of molecules read by the pads is sent to the Pattern Buffer, a large cylindrical tank surrounded by superconducting electromagnetic coils. It is here that the object to be transported is stored momentarily before actual beaming away from the ship (or even within the ship). It is the Pattern Buffer and its associated subsystems that have been improved the most in the last half-century. While the actual molecules of an object are held in a spinning magnetic suspension (eight minutes before degradation), the construction sequence of the object can be read, recorded in computer memory (in some cases), and reproduced. There are limits to the complexity of the object, however, and this is where the potential "miracle" machine still eludes.

The Transporter cannot produce working duplicate copies of living tissue or organ systems.

The reason for this is that routine transport involves handling the incredibly vast amount of information required to "disassemble" and :reassemble" a human being or other life form. To transport something, the system must scan, process, and transmit this pattern information. This is analogous to a television, which serves as a conduit to the vast amount of visual information in a normal television transmission.

(Note: This was written when all TV was still analog and DVDs were not yet out -- and remember that we could transmit TV signals before we could actually tape and keep them.)

Continuing to quote from the same passage:

Storing that information, however, is another matter. In our analogy, it would be like comparing a television (which is incapable of storing an image) to a videocassette recorder, which can store a relatively low-resolution recording of a television program. In order to store the patterns for a human being, one would have to record not only all the atomic and molecular configurations, but all the quantum and energy states of all the electron shells, and the brownian motions of every sub-atomic partical of every atom. While we cannot store all of this incredibly complex information, we can use it as it is being handled in real time.

So the information and matter taken from the original and needed to reconstruct the duplicate are taken from the original as it is dismantled, then place in the "stream." (I consider that a loose term, since all of it, matter and energy, goes through the pattern buffers and through an actual stream confined by the annular confinement beam, or ABM.) We can skip all the steps and say the stream goes from the original, through a bunch of stuff, to the new version, wherever that is. And once there, it is assembled, particle by particle, in the new location.

Now, we know what even solid matter is mostly empty space. So it wouldn't be hard, each time a particle is put in place, to use some kind of force to repel any in the way. While it's never stated this is done, this process takes an actual particle and places it in the new location, then places another molecule, and another. Since the molecules are not going through some kind of energy/matter conversion or anything else, but they are just molecules, if something were done with the matter in the area, we'd see some kind of explosion form the energy. (Either particles would be split, merged, or otherwise messed with at a sub-molecular or sub-atomic level.)

So the air molecules would essentially have to be moved aside for construction of the solid (or liquid) form out of molecules flowing out of the ACB.

This would also explain why someone could partially materialize in a bulkhead or something. Even in a rock, there's still space between molecules. I don't remember if we've seen a person or object that materialized in another object, but I seem to recall, it looked like the two parts were just melded together, with one coming out of the other.

If anything were done, such as "destroying" the particles that were there, we'd see indications of either explosions or significant radiation, which would make using the transporter too many times dangerous.

  • 1
    I don't remember if we've seen a person or object that materialized in another object, but I seem to recall, it looked like the two parts were just melded together, with one coming out of the other. - Yes, that's what the picture in my answer is of. Those are stones, leaves, twigs, etc, coming out of the crewmember's skin. It was ENT, not TNG, though.
    – Izkata
    Sep 5, 2012 at 10:51
  • I'm glad you recall it, too. I remember it happening, but can't remember a specific incident, or which series. As to the image being in ENT, pretty much anything after TNG used the same background, since Okuda and Sternbach were still with the franchise and handling that kind of thing.
    – Tango
    Sep 5, 2012 at 14:29
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    "The Transporter cannot produce working duplicate copies of living tissue or organ systems." - umm, Thomas Riker? Jul 23, 2020 at 3:26
  • 1
    @Tango "plot-onium" or not, it's still canon. The TNG crew knows what happened, so whose to say the conditions couldn't be duplicated so a new kind of 3D tissue replicator/copier technology is invented. Jul 23, 2020 at 7:44
  • 1
    @RemyLebeau: Okay, it's a very common version of plotonium - it's actually unrefined plotonium, called canonium.
    – Tango
    Jul 23, 2020 at 22:30

Actually this is problematic on a few levels. If the teleported object is reconstructed from atoms at the destination point, then there would be a massive shockwave and heating from an equal density volume of air. And it wouldn't work in a vacuum.

If the transporter uses another method of reconstructing atoms eg from 'quantum foam' then it needs to be stabilized by cooling it down massively eg. Optic cooling/trapping which seems reasonable but the atoms need to be created from energy - massive amounts. Atomic level explosions. Or supplied e.g. by an atom maser but then it's line of sight only. But interesting possibility. This style of transporter is also covered in Accelerando.

If the transportation is through a wormhole like method, then it is 2 way so you get dual contamination both ways through the throat of the wormhole and what happens to inertia? Beaming from the equator to a pole could send you flying off at a massive speed.

My guess is that the holographic reconstruction of atoms in the arrival space displaces or destroys the equivalent volume of matter.

If we ignored the above and did a thought experiment of this: For 7 people, 2m tall, 1m diameter cylinder each, packed into a sphere you are looking at displacing a volume of approx. 14m^3 over a surface area of 28m^2 = 0.5m / re-integration time in sec.

I am simplifying here by assuming all the air volume is at the edge of the sphere volume. With a centre point expanding out - your wind strength over 1s varies from 0.5-3 m/s which is a gentle-fresh breeze (branches sway).

The faster the reintegration time the more "explosive" this becomes. Hurricane strength at 32 m/s or a reintegration time of 1/10 sec. But dissipating with the square of the distance so not noticeable further than say 6m away.

Note: from iphone at 5am, might be a couple of typos here.

  • Nice explanation here. Still hoping to find some canonical coverage of how they work around this, though.
    – Iszi
    Aug 27, 2012 at 23:48
  • it is an energy beam that sends all the material needed to reconstruct the object, it doesn't take anything from the destination. this is one of the reasons they can't do it through shields.
    – Malachi
    Sep 8, 2016 at 16:59

Perhaps the transporter or replicator pads create a vacuum while the transport is in progress and the matter stream completes the transports from the center of the mass to the edges, causing the air to move as it's rematerializing.

  • I believe this is true. The transporters create a stasis field on both ends, the receiving end is in a vacuum. I don't have texev for that though.
    – Zan Lynx
    Aug 28, 2012 at 15:12
  • @ZanLynx It was only in ENT and TOS that the crew was seemingly frozen during the transport. Later chronologically (TNG/DS9/VOY/Movies), the transportee was able to move while in the beam.
    – Izkata
    Aug 29, 2012 at 22:41

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