What would be the effects of warp collisions?

Triggered by a recent question I was wondering what actually would happen to a ship (e.g. the Enterprise-D NCC-1701) that collides with a stationary object such as a) another ship of a similar configuration or b) a gigantic structure like a moon or even a planet.

We know the deflector is supposed to keep interstellar dust (not to be confused with ordinary dust, which is a different thing) from ripping large holes in the ship.

At first, one thinks "Obvious. Everything explodes." But does it really? Would the deflector manage to actually deflect both masses? If not, where is the threshold of what a deflector can handle? Would the ship maybe tunnel right through the object, because of wibbly-wobbly space wobblification by the warp field? It does do some weird things to the space right in front and behind the vessel.

Important remark: We cannot approach this with what we know about physics at all. For all intents and purposes, both ships must measure the other ship travelling faster than light, resulting in it having infinite (or rather undefined) mass and by extension momentum. If we start with that reasoning any ship jumping to warp would suck in the entire universe (it takes a moment, but think about it). So, obviously we cannot apply our intuition (even our relativistic intuition) here.

• The remark isn't entirely correct [in Star Trek lore of course]: The ships don't actually travel faster than light, they create a warp bubble around the ships, and it's the warp bubble, warping space-time, that moves. The ship barely moves at all inside the bubble. So really, the question comes down to 'what happens when a warp bubble comes into contact with a stationary body... Commented Aug 25, 2012 at 17:33
• @NickShaw: My rationale is that: Measure the distance from Sol to Proxima Centauri (about 4.2 ly) and measure the time it takes a ship to travel that distance. From the observer's point of view, that ship travelled faster than c. Commented Aug 25, 2012 at 18:10
• Does this question also encompass warp fields hitting/touching other warp fields, or just other non-warp objects? (Title leaves it ambiguous) Commented Aug 25, 2012 at 20:09
• @Izkata: I was mainly thinking about hitting stationary objects. See the first sentence of the question body. It would probably get even messier (i.e. unanswerable) if two ships travelling in warp were to collide. --- Maybe the warp fields would merge and the two ships would slowly bump into each other? Commented Aug 25, 2012 at 20:40
• I remember Enterprise and one another Starfleet vessel had to come closer at warp speed to transfer Warp Engineer using rope (possibly there was a speed bomb inside one ship). At that point, warp fields of both ships had merged. It means that the ships would collide normally and their warp bubbles would merge. But, maybe it is limited only to Starfleet vessels or only if warp field frequency of both ships are known. Commented Sep 10, 2018 at 0:30

The Warp Drive does not produce momentum - it literally warps space around the ship, dragging the ship and its adjacent bubble of normal space, through the time-space medium.

The deflector is there to prevent things from entering into the bubble, as the normal transition speeds are in the cruising impulse range, which is between 0.25 and 0.6 C, per various canonical, semi-canonical, and extended universe sources. The ship is moving within that bubble, and the bubble being moved to keep up, so materials in front of the ship can get pulled in, and become a hazard due to their and the ship's residual n-space momentum.

We see this effect in part in The Motion Picture - the wormhole effect when the asteroid isn't deflected, and is about to impact the ship.

A warp ship impacting a non-warp object should produce a lot of distortion, impart a lot of energy, and quite likely, draw a solid object in, potentially quite compressed by the subspace distortion which is the ship's warp field's (invisible) event horizon.

This bubble effect pretty much also explains why the ship can still see the stars to the side... their photons have momentum sideways, and within the bubble, continue on that same vector; a ship in warp should leave a distortion wave behind of displaced photons...

In any case, assuming no warp field interactions, two ships impacting would invariably impact based upon their pre-engagement vectors and energies - still plenty sufficient to total the two ships, as we see with the USS Bozeman... until the Enterprise snaps out of the temporal anomaly by NOT entering the time rift, it repeatedly loops and the impact at low impulse is sufficient to destroy both the Bozeman (a miranda class) and the Enterprise D.

• Warp field's event horizon? I am sure this doesn't exist in Star Trek. Commented Nov 4, 2018 at 3:55

There is one instance I can think of that suggests there wouldn't be a collision, per se, but definitely cause devastating damage: TNG 4x05, Remember Me, where Beverly Crusher gets caught inside a static warp bubble.

There's a couple of important points I can think of:

• Beverly wasn't harmed, but she was trapped - contact had to be made from the outside.
• The warp bubble travelled with the ship, inside the Warp core.
• There didn't seem to be any harm to the ship due to this event, but Beverly is quite small compared to, say, a Borg cube - and the bubble itself was also quite small.

This suggests that when plain matter comes into contact with Warp fields, it gets drawn inside somehow. Warp bubbles provide no propulsion, but the same technology and physics definitely seem to be behind both of them: The Traveler was involved, Wesley had to use the Warp core for his experiment, and so on.

Looking at the Memory Alpha page for Warp fields, it says that the subspace field envelopes the ship. So if we can apply what happened in Remember Me to the general warp field, I would expect a hole the size and shape of the warp field to be torn through that object, and the matter pulled inside the field.

I agree with @NickShaw's comment that the ships themselves - and whatever else is inside the warp field - don't have momentum. It's been shown pretty often that when a ship drops out of warp, it's not moving quickly at all. So the debris from the object collided with would appear to be nearly stationary once inside the ship, but it would pile up absurdly quickly.

However, the edge of the Warp field is a distortion of space, so matter passing through a Warp field - unlike a Warp bubble - is extremely unlikely to remain in one piece. This was why the Columbia and the Enterprise had to merge their Warp fields: So Trip wouldn't get shredded.

While the Warp field would get quite crowded with all the debris (probably causing damage from pressure on the hull, and so on), I don't believe we have any way of knowing what direct damage would be caused to the ship's systems. There may be none, as mentioned in the third bullet point above, or there may be massive damage, due to the relative size of both the warp field and the object being collided with.

• I can't remember the book, but the reason that warp missiles don't exist in star trek is because if the matter concentration is too high when they come out of warp, it destroys everything inside the subspace bubble... that's why you don't come out of warp into an planets atmosphere. Commented Aug 25, 2012 at 18:39
• So, to summarise, the warp bubble would rip the stationary ship to shreds but the ship travelling at warp would remain relatively undamaged except by a few small objects of debris. Right? Commented Aug 25, 2012 at 19:31
• @bitmask All the mass that came from the stationary object gets shredded and sucked inside the warp field - it's far from "a few small objects". I didn't mean to imply it disintegrates into nothingness - the mass would still exist, it would just unrecognizable and trapped against the ship. Commented Aug 25, 2012 at 20:03
• I meant lots of small objects. Obviously, the mass (or rather, the energy) must be preserved. But the deflector can probably handle lots of small objects (one at a time?) better than one object of the same mass. Commented Aug 25, 2012 at 20:37

Within the Trek universe, ships travelling at warp speed are still capable of interacting with normal three-dimensional matter (with potentially disastrous consequences). This is why ships use a series of nested static shields known as navigational deflectors to move particulate matter out of the way, tractor beams to move medium-sized objects and sensors to detect and avoid larger objects that could prove a threat.

In TNG: Best of Both Worlds, Part II, Riker orders a collision course at warp, implying that this would have a more devastating effect than a collision at sublight speeds:

RIKER : Mister Crusher, ready a collision course with the Borg ship

Wesley reacts, turns and looks for confirmation...Repeating --

RIKER You heard me. A collision course.

WESLEY : Yessir.

RIKER : Mister La Forge, prepare to go to warp power...

and in Star Trek : The Motion Picture the crew have to take evasive action to avoid hitting an asteroid while travelling at warp:

DECKER : Negative control from inertial lag will continue 22 point five seconds before forward velocity slows to sub-light speed.

ILIA Unidentified small object has been pulled into the wormhole with us, Captain! Directly ahead...!

KIRK : Forcefields up full! Put object on viewer...!

The picture is switched through two further levels of magnification, enlarging the object: an elongated, distorted, pitted asteroid, tumbling toward the Enter- prise on a collision course.

CHEKOV (punching button) Torpedoes away...!

EXT. SPACE - PAST THE ENTERPRISE AND THE ASTEROID

as the starship's photon torpedo tubes EJECT GLOWING
BALLS OF LIGHT ENERGY, which seems to float toward the
oncoming asteroid, almost too slowly. And in these
brief seconds, the asteroid hurtles at the Enterprise,
the huge pitted rock growing even larger than the ship
itself. It FILLS THE SCREEN, as the photon torpedoes
hit, disintegrating the asteroid into thousands of
fragments. Instantly, these fragments pulverize them-
selves on the ship's forward forcefield and deflector
screens. The smaller pieces burn up on impact, clearly
outlining the ship's forcefield barriers.

INT. BRIDGE - INCLUDING MAIN VIEWER

The asteroid fragments still smashing into the force
field screen; the smaller bits like SPARKLERS as im-
pact heat consumes them. The larger sections bouncing
away, the bridge QUIVERING as they hit.

Then one final gigantic fragment strikes, the bridge
SHUDDERS. And then the viewer shows only the normal
SUB-WARP EFFECT: The stars ahead, relatively station-
ary; a feeling of motion, but smooth, visually normal.

As regards the usefulness of the Navigational Deflector, in at least one episode of Voyager (Year of Hell, Part II) do we see the effects of it becoming inoperative (albeit in this case it's the objects that are moving at speed, not the ship)

KIM: Captain, with the deflector down those micrometeoroids are beginning to erode the hull.

JANEWAY: Emergency power to the deflector.

TUVOK: None available.

• While it is not Star Trek, the new Star Wars: High Republic brand kicks off by going into great detail about Star Wars’ version of “warp speed.” The novel Star Wars High Republic: Light of the Jedi has this media synopsis: “When a shocking catastrophe in hyperspace tears a ship to pieces, the flurry of shrapnel emerging from the disaster threatens an entire system.” The plot is interesting for its rather detailed service to the physics and problem of very fast-moving objects colliding and the resultant it can produce. Commented Sep 29, 2021 at 19:27
• @SillybutTrue - Don't even get me started about that Commented Sep 29, 2021 at 19:28