I asked a question earlier on here concerning Negative and Heavy Matter - hypothetical types of matter I created to have a working FTL drive. With some extra work, I’ve tweaked the concept and been able to make an FTL drive I feel is pretty self-consistent. I’m asking this because I want to know if it is, or if there are any glaring flaws in its system of operation.

How the engine works

In the centre of the drive is a column of gas. This gas is an element that, when strongly heated, emits radiation that can convert ordinary matter into negative matter. This gas belongs to a class of matter called Heavy Matter, which strongly attracts Negative Matter - when Heavy and Negative Matter meet, they cancel each other out and convert back into normal matter. (I’ve worked all of these processes out on the subatomic level too but none of that is relevant to the workings of the engine.) The gas is heated to the point that it becomes a plasma, meaning a) it emits huge amounts of this radiation b) it can be confined by a magnetic field. Surrounding the confined column of gas is a vacuum - surrounding the vacuum is a much larger cloud of gas; it doesn’t really matter what element this is, let’s say it’s hydrogen for sake of argument.

The radiation hurtles outwards, converting the gas into negative matter. To maintain the vacuum gap between the negative and heavy matter (because otherwise the negative gas would drift inwards and convert back into ordinary matter as it hit the heavy matter in the centre) the whole drive is spun very rapidly, causing the cloud of gas to stick to the interior wall due to centrifrugal force.

The FTL itself

Once enough negative matter builds up, spacetime is warped, causing the entire ship to travel faster than the speed of light. The negative matter will be drawn to whichever heavy matter is exerting the most force on it - because very massive heavy matter at long distances exerts more force than fairly light heavy matter at short distances, instead of warping to the centre of the engine, it warps the entire ship over to a large concentration of heavy matter, deliberately placed as a beacon. Large concentrations of heavy matter nullify the effect of the warping, thus causing the ship to drop out of FTL once it reaches this beacon. This allows the ship to travel at superluminal speeds between regularly spaced beacons in the universe.

Once the ship is stopped at the beacon, the plasma is drained, the spinning stopped, and the entire chamber flooded with water. Normal matter reacts with negative matter to form radiation - the result being that the accumulated negative matter is destroyed along with some of the water, readying the ship along with the next jump.

Attached is a cutaway view of this drive.

What do you guys think? Allowing for the mechanisms of Heavy and Negative matter, how feasible is this? Are there any issues or interesting effects I haven’t anticipated? enter image description here

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    $\begingroup$ You might want to reformat this post in a few ways; split up that wall of text for easier consumption, and rotate the image to display horizontally so folks don't have to crane their necks to look at it. $\endgroup$ – jdunlop May 17 at 15:51
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    $\begingroup$ This is not similar to any description of the Alcubierre Drive I have ever heard. It sounds essentially like saying you can reach light speed if you have a really strong magnet at your destination and if your ship is made out of "negative matter". Whatever that is and how it relates to regular matter is unclear. It's also unclear how the ship is supposed to survive ramming head first into the "magnet" at the destination at superluminal speeds. Or how it fully converts back to regular matter. $\endgroup$ – Muuski May 17 at 17:11
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    $\begingroup$ By the way, there is also an argument that even if we managed to build an Alcubierre Drive that it still would not achieve FTL. You see, the drive must warp spacetime in order for the ship to pass through it, however the information of that warp cannot travel faster than light, so the best you can hope for is a little less than light speed. Now, if you warp the spacetime from the source to the destination ahead of time, THEN you can travel faster than light. But I believe these are called Krasnikov tubes. $\endgroup$ – Muuski May 17 at 17:14
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    $\begingroup$ I recommend swapping the science-fiction tag with the reality-check tag. You're asking a reality-check question and the sci-fi and sci-bas tags don't usually go together. $\endgroup$ – JBH May 17 at 19:42
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    $\begingroup$ Almost everything in this question is irrelevant noise, i.e. details that don't really affect the question itself. It could all be reduced to "Are there any issues with this FTL drive concept? ... spacetime is warped, causing the entire ship to travel faster than the speed of light.". The entire question describes in detail how spacetime is warped, but provides no information about why warping spacetime would cause the ship to travel faster than light. $\endgroup$ – Ray Butterworth May 18 at 0:58

Yeah? I mean: you’ve kinda created some handwavium at the point you say ‘spacetime is warped’ with no further explanation of the physics or mechanism behind it, at which point you may as well simply say ‘Our drive uses negative matter to warp space between it and the nearest heavy matter beacon’, and simply don’t mention the internal workings of the drive (unless it becomes a plot point).

One immediate issue is that your forces are working backwards. Beacons further away exerting more attractive force will lead to ships stranded in interstellar space, unable to move towards any beacon because of the attractive powers of the other beacons. Unless you can add some form of directional selection to your ‘space warping’ you’re basically going to get stuck where you are. If you’re more attracted to close, heavy beacons then you are distant ones then you just end up stuck at whatever beacon you’re at, unable ever again to taste sweet freedom. If you can ‘shield’ your drive from the effects of beacons in any given direction, or if multiple warp vectors start to form and you can choose which to set off along then you can avoid this issue.

If you fix that another issue is all of the stuff between your ship and your target beacon. It’s about to get torn apart by a spontaneously forming corridor of warped space, or possibly hit by the leading edge of a bubble of warped space. Alcubierre based warp metrics don’t take your ship out of normal space: it’s still here, just wrapped in a bubble of immense tidal stresses. A major flaw with the Alcubierre-White warp metric (Alcubierre being the guy who came up with it, White being the guy currently working on it) is that particles (both of interstellar dust and virtual particles from the quantum foam) get stuck on the bubble. Depending on how you run the numbers this either means the inside of the bubble becomes incandescently hot or your destination is about to be bathed in a rather major wave of high energy radiation. Both of these are Bad For All Involved, so you should consider dedicated space lanes with rigorous traffic control procedures.

There are other issues. One is time travel, more specifically the fact that you can’t have special relativity, FTL and causality in the same place because simultaneous events aren’t. You can potentially get around that with a liberal application of general relativity, but then you risk messing with gravity or time (or both) in unexpected ways. Another issue I assumed to be handwaved by your new exotic matter is spontaneously blowing up your ship by annihilating large amounts of matter, as mass is proportional to energy (Thanks, Einstein), and you can’t get around conservation laws, so the first and final steps of your drive function (conversion of regular matter to an exotic state, then annihilation of said matter) result in needing then releasing frankly ludicrous amounts of energy. But hey, it’s a writer’s prerogative to ignore these issues, as long as it makes the story better.

So yeah, utterly non scientific and has issues, but as totally handwavy soft science FTL drives go i’ve heard worse justifications.

  • $\begingroup$ The warp part isn’t handwaved. It’s based on the Alcubierre Drive - look it up. General Relativity predicts that an accumulation of negative mass (technically, negative energy density) will lead to the creation of a warp bubble that travels FTL without interacting with anything in its path. $\endgroup$ – Locaq May 17 at 17:41
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    $\begingroup$ @Locaq: You have handwaved. Regardless of what you’ve based it on, the interaction you’ve created is a handwave. You’ve invented an exotic state of matter then stated it acts (in some way which is actually very unlike the physics of an alcubierre drive) to warp spacetime like an alcubierre drive. That’s a handwave. It’s a perfectly fine one, but there’s no way we can critique it as it is fundamentally your creation. $\endgroup$ – Joe Bloggs May 17 at 18:12
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    $\begingroup$ @Locaq: I spent a lot of my uni days and more time than I should have afterwards digging into the physics of the Alcubierre-White warp metric and it’s attending engineering problems. Alcubierre drives definitely do interact with things in their path: in fact one of the major flaws in the alcubierre drive is superheated plasma on the hypothetical ‘front’ of the bubble. $\endgroup$ – Joe Bloggs May 17 at 18:13
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    $\begingroup$ @Locaq: If mass is also taken into account then every ship will end up stuck to the heaviest beacon. Same issue: you need some form of directionality to allow you to ‘aim’ your warped space, a simple distance/mass equation turns into a minimum-energy-state optimisation and your ships will end up in some local minima, unable to get out. $\endgroup$ – Joe Bloggs May 17 at 18:17
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    $\begingroup$ @Locaq More details added. :-) $\endgroup$ – Joe Bloggs May 17 at 18:31

Are there any issues or interesting effects I haven’t anticipated?

The centrifugue must necessarily be located within the ship. And this means that, when the space around the gas distorts, the ship will be distorted as well.

This has the potential to break not only molecular bonds, but also the bonds between subatomic particles as well. Your version of Alcubierre might have just plasma arriving at the destination.

Also notice that it is debatable if even Alcubierre's drive can provide actual FTL travel. See Muuski's comments on the question.

  • $\begingroup$ I’m not entirely sure I understand could you clarify? $\endgroup$ – Locaq May 17 at 19:48
  • $\begingroup$ You are distorting the space between particles inside the ship. That does not bode well. $\endgroup$ – Renan May 17 at 20:06
  • $\begingroup$ Ah, fair point. $\endgroup$ – Locaq May 17 at 20:20

This is really basic question, not highfalutin' like the other questions here, but...

What is the diameter of the tube, and how fast does your tube have to spin, to create a vortex that has a vacuum in the center?

You have the cutoff between "NM gas" and "vacuum gap" be sharp, but I think it would be some kind of gradual fade, though I'm not sure if the density-curve of that fade would be linear.

I do not think, through rotation, that you can accomplish anything even close to a perfect vacuum, particularly given the energies (and hence, gas pressures) involved.

If you've already done the math, great, I won't bother.

If not, we probably need to calculate it, and I'm suspecting that you might need to pass light speed for your centrifuge walls in order to get the vacuum, and you'd end up compressing almost all of the gas down to a liquid.

  • $\begingroup$ Yeah I doubt it’d be a perfect vacuum. Considering the central part of the engine is far hotter than the outer parts, gas wouldn’t flow inwards that much anyway. It’d just need to rarify the gas between the plasma and the cloud enough that the negative matter wouldn’t be destroyed. $\endgroup$ – Locaq May 17 at 19:49
  • $\begingroup$ The heat is energy, which would excite the gas atoms, so, yes, the heat would cause it to flow inward a LOT. This feels like it will break your mechanism completely, and probably needs us to do the math. But that seems like a separate problem, worth a separate question :) $\endgroup$ – Dewi Morgan May 17 at 20:11
  • $\begingroup$ This was an interesting question in itself, so I asked it here: physics.stackexchange.com/questions/480713/… $\endgroup$ – Dewi Morgan May 19 at 19:22

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