Positive Energy Warp Drive from Hidden Geometric Structures
arxiv.org
arxiv.org
Edit: And as others are pointing out, communication. There's a whole slew of technologies that could be improved/invented if you can move things/information FTL.
[0] https://www.esa.int/Safety_Security/Space_Debris/Hyperveloci...
Its becomes clear by the end that the ansibles being used were creating philotic threads throughout the universe. So the very thing they had been using for FTL communication was building a huge network. This allowed them to not only save the trees by uploading them, it akso allowed Ender to be brought to no-space where he was able to subconsciously create young Peter and Valentine.
So, they ended up being central to the entire story.
You're welcome.
1. The original topic was about Ender's Game only, not the entire series, so you basically shifted the goalposts. 2. More importantly, I think you are using the wrong literary terminology and you and the others are talking over each other. Where you say "plot point" I believe you meant "plot device."
The Ansible is definitely the primary plot device that makes so much of the story and how it flows possible, but the ansible is not the point of the plot itself.
Throughout Ender's Game the plot point is reinforced that the rules of civilization will be broken when a credible threat shows itself. That is shown with the various physical conflicts Ender has with the other children at the individual level, it is shown with the tolerance the military has in order to shape Ender at the organizational level, and it is shown with the vilification of Ender so society at large does not have to grapple with just how badly it broke its own rules - so it can be done again if necessary for survival.
For the greater series though, it's basically the core concept of the story arc's plot.
I highly approve.
• Tablets (the padds)
• VR "holodecks"
• Computers that you can talk to and ask questions
• "Tricorders" (smartphones?)
• Turbolifts (https://www.dezeen.com/2017/07/12/thyssenkrupp-unveils-world...)
Maybe we'll get to add a warp drive to the list by the time I die.
What else?
You've got Tricorders wrong, they're a generalized non-contact diagnostic tool; someone was working on one but it was just a load of diagnostic devices stuck together. We've got body temperature, and pulse is doable, but not sure what else can really be added to a Tricorder, maybe a tiny mass-spectrometer gets you part way there.
In fairness, a tricorder would probably need to be a device capable of gathering data about quantum fields within an extremely local region of space and then analyzing based on known frames of reference and data models, so we're probably a ways off on that one.
The harder part of that challenge is building a device capable of analyzing quantum fields in the most abstract sense. But once that's done, even if it's in the form of a massive machine that can only analyze spacetime in a small chamber, even if that machine is rooms-big, the race to the first tricorder begins.
(I could be completely off-base with my comment on analyzing quantum fields. I'm not at all an expert.)
TOS-style communicators are basically flip-phones with absurd range.
Given that WiFi signals can be used as wall-penetrating radars capable of pose, breathing, and pulse determination, that could be added without too much difficulty.
Likewise broad range IR and UV cameras (which I assume will become standard when phone manufacturers can no longer differentiate by zoom, just as they added zoom when everyone had enough megapixels).
Geiger counter would probably just upset people when they realise even organic bananas contain radioactive potassium, but could be done.
Carbon monoxide and other air quality sensors are fairly plausible IMO. Not sure how many you could put in a phone (zero? Just CO? Whole mass spectrometer?), but I can see the desire.
Make an atomic clock good enough and small enough, and you could detect temporal anomalies caused by the nearby football stadium filling up (no, really: https://news.ycombinator.com/item?id=26582161)
My head-cannon is the small cylinder prop used in the medical tricorder is supposed to be a miniature MRI or CT scanner. I suspect either would be a mistake to add to a consumer product.
- Identify places and objects with the camera and give me data about them (Google Lens)
- Plot graphs of the local geomagnetic fields, my exact position on earth (the built in compass and GPS)
- Plot graphs of local radio traffic, signal strengths etc (wifi scanners)
- Control other devices
- Diagnose medical conditions
Smartphones can do a lot already just with the sensors they already have.
Pity the answers are so often rubbish and the "side-effects" so obnoxious. ST (and most other SF) seems not to have predicted that.
And the VR Holodeck is spot on actually. I was having moments where I was questioning how much better the experience really would be with a matter-energy converter. It already works pretty well using stupid human perceptual tricks.
Wikipedia is excellent, as usual. But it is an encyclopaedia, not a definitive source of original knowledge, and it remains the case that I can browse my modest (physical) bookshelves and find a book on, say, Russian modern history that will give me far more in-depth information in the first ten pages than I can find online. Same applies for almost any genre, except perhaps fiction. Seven Years In Tibet taught me more about Tibetan geography and culture than any amount of Googling could do.
The idea of an infinite knowledge bank is appealing and I think the Internet could have made it - imagine a suite of applications that complement Wikipedia - but commercialism has ruined the utopia, as it is designed to do.
He wanted to do the holodeck already back then, but there was no way to do it reasonably convincingly given the technology of the time.
This is like a medieval person cautioning against the development of jet engines due to how fast they could make a catapult swing.
What? That's a bit overkill, don't you think? I got a this pebble that'll do the job just fine.
But a decent way to beat Einstein would be find and implement an actual FTL engine: after all, if you can do it then obviously the theory isn't correct (alternately: the universe possible does not care about causality as much as we do in our little bubble of perception).
True, but if the energy requirements for warp drives continue to be measured in Jupiters, reaction-mass is the least of your worries.
[0]: https://arxiv.org/abs/2105.03079
[1]: https://eriklentzphd.blogspot.com/2021/05/response-to-new-pa...
What may add the arrow of time is the second law of thermodynamics: a statistical evolution of a system is not symmetric.
I wonder now how a violation of causality could either circumvent of contradict the second law.
To add something substantive, my question to the thread is: anyone here have thoughts on how these questions relate to McTaggart's unreality of time? https://en.wikipedia.org/wiki/A_series_and_B_series
Moving energy around through time may serve to increase entropy overall.
You can't be a scientific american if you keep using the science words bad.
It's like cargo culting science: Use these words correctly if you want to seem to know what you're talking about!
But anyone who actually knows what they are talking about would use these words correctly, or at least not be mistaken about their meaning.
So this article is teaching people that have no idea what they're talking about, how to sound like they do.
Maybe it's time we start using another language for science. Clearly it's confusing the Scientific Americans.
At some point a particle pops up into existence in B, increasing B's pressure.
Some time later, a particle from A disappears, decreasing A's pressure.
This pressure differential would cause flow from B to A through X.
Alternatively, a particle randomly disappears from B, decreasing B's pressure.
Some time later, a particle appears in A, increasing A's pressure.
This would cause flow from A to B through X.
The more particles that cross from A to B via Y, increasing B's pressure, the more likely it is for particles to pass from B to A via Y, keeping these two effects equal.
These two pressure differentials would cancel out for large numbers of particles.
You've essentially just hooked up the system to itself, but at a future point in time. Unless the overall pressure of the system is changing, there is nothing to induce the flow. If you are increasing the pressure, valve Y is essentially just a standard one-way valve.
It's clear that your point of view matters in physics, but it's also clear that I have no idea what a "point of view" means in this context.
If I am stationary and measuring you flying past me in a relativistic train, I would measure you in a coordinate grid say, centered on myself. You may be watching me from your train and doing the same, but from a reference grid stationary with respect to you but moving with respect to me. Even if we both agreed on identical measures ahead of time, your measurement of me from your reference frame and mine of you from my reference will be off from a measurement we do ahead of time in the same reference frame as a calibration. However, that difference comes out in the wash through the magic of the Lorentz Transformation. Using the Lorentz Transformation, I should be able to negotiate transforming a measurement I do of you in my own reference frame to what it would look like from yours and you should be able to transform yours to mine, through which we'd both come to the same numbersassuming we're in spacetime that shares the same general degree of curvature (same gravity). This can even be generalized to arbitrary degrees of spacetime curvature. I.e. if your relativistic train is racing past a black hole with a near tangent intersect, and I'm stationary with reference to the black hole centric reference frame but further out in the system, as you blast through the high curvature part of your trip your clock may seem to de-sync from mine. This too, however, can be mitigated through copious amounts of math I don't get for more than half an hour after looking away from a text book. I just know if I ever have a problem to solve that involves hitting that book again, I have either made some terrible or awesome decisions in my life.
You need to impose additional constraints on the theory (e.g., real mass conditions) to get rid of them.
(Again I may have misunderstood, but the frame of the CMB sometimes gets talked about as if it might be a preferred frame).
If light is just information, wouldn’t it just be a matter of seemingly getting something very fast?
Everytime I think I get it, I don’t!
If we perceived the world through sonar then causality would be violated by anything supersonic. If you were shot then you'd feel the bullet first and then "see" it moving back into the gun.
AFAICS if information can travel at >c, then physical objects traveling at >c doesn't violate causality
http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-ti...
The sonar example works only if everything is traveling in roughly the same frame of reference. You're not accounting for relativity and its effects on space and time in your analogy.
If you draw a tachyon on a spacetime diagram going faster than the speed of light, you can create situations where the tachyon travels back in time for certain observers.
> AFAICS if information can travel at >c, then physical objects traveling at >c doesn't violate causality
If information can travel faster than c, then you can create situations where it's also violating causality.
Can you explain how traveling faster than light leads to that? Perhaps you meant "observing your own past?"
Technically that's only one assertion (that is, the second is a strict subset of the first).
You can calculate the speed of light from other physical, measurable constants without using light (the permittivity and permeability of free space). Those you can measure with inductors and capacitors. So because those measurable physical behaviours are invariant in all reference frames under SR, it follows that the speed of light is also invariant.
You don't have to measure c, or calculate it. The causal chain goes the other way - we assume c is invariant and define capacitance and inductance in terms of it (c, that is).
Edit: I'm totally this guy right now https://xkcd.com/386/
That is what I just said: the meter is defined in terms of c, not vice versa.
Here's the grid coordinate system for the streets in my town. One intersection is (0, 0). But in the grid system used by the next town over, that same intersection is (100, 200). And that's fine - we're just shifting the origin, which changes all the numbers.
The same thing happens with velocity. If I'm on the ground, "stationary" means that you're not moving with respect to the ground. If you're in an airplane, "stationary" means that you're sitting in your seat, and you see me on the ground moving toward the back of the plane at 550 MPH. And that's still fine - we just shifted the origin of velocity.
Light is unique in that, when you shift the origin of velocity, it's speed is still the same number. No other velocity transforms that way.
(Well... light isn't quite unique. The speed of light is unique in that way. But gravitational waves also travel at the speed of light.)
Right - this is a subtle but important distinction! Photons don't have primacy, space-time does.
c isn't defined as the speed of light - light travels at c, but so does everything else, when you factor in movement through time.
https://old.reddit.com/r/askscience/comments/l9sba/why_does_...
I feel like this is the part that would probabally be hard (ie not possible) when going faster than light, assuming such a thing is possible.
Also whatever magical space warp it is that lets you go that fast could presumably also obscure your ability to see yourself in the distance.
Slowing down to reach the speed of light might be as hard as speeding up to reach it; I remember it played a role in the theory of tachyons, hypothetical FTL elementary particles which could not be slowed down.
Another question for the thread: Anyone here feel like they can feel the Coriolis effect if they focus enough? I haven't travelled across the equator enough to know if the north/south jetlag is different from east/west.
The coriolis force differential, besides being rather small to begin with, has the additional problem that the coriolis force is proportional to the speed at which you're moving over the earth. If you were to accelerate to a speed where the coriolis force differential might be appreciable (e.g. by sitting in a bullet train or in a plane), it will be completely drowned out by any other momentary forces imparted upon you by the vehicle (trains or planes can move mostly straight, but not in a mathematical-grade straight line).
In the tachyonic antitelephone example, Bob and Alice send messages that travel at 2.4c, but neither observers are at that speed. Wouldn't the limits of their observation and time dilation cause the messages to appear in order?
If you were to theoretically travel into a black hole, and then somehow escape out of it very quickly, you would see yourself still in the black hole, but you wouldn't see yourself coming out of it, because that light was further from the black hole and thus moving at a different speed?
Being able to observe your own past is a given after FTL travel, and the most important thing: it's a given that relies on almost no assumptions about the deeper mechanics of the universe. If you instantly teleport to Alpha Centauri, you will be able to see your old Earth photons for years.
> Instead, your past self could observe your future self.
Now that statement (like the Tachyonic antitelephone) relies on some assumptions that we can't test yet. My hunch would be that either an as-of-yet unknown non-local temporal dimension (or synchronization mechanism) exists at the foundations of the universe, or that FTL travel is indeed impossible. One excludes the other would be my intuition.
First of all, it gives you the ability to solve NP-complete problems trivially.
Step 1: you receive a message from yourself from the future. It explains the problem, gives you a potential solution. Let's say you ask yourself to solve boolean satisfiability, gives you the problem statement, and then a potential solution. You check the solution: If the possible solution is correct, you send yourself an identical message. If the solution is not correct, you send the next possible permutation of the answer. So if you sent yourself the possible solution TTFTFTTTFTFFTTTFTF, you send yourself TTFTFTTTFTFFTTTFTT. If there are no further possible permutations, then you send yourself a statement saying that the problem is not solvable. You've created a time paradox; a future in which you send yourself an incorrectly solution is logically inconsistent. The only consistent universes are the ones where you send yourself the correct solution or not-solvable, and all other universes (starting with the one where you sent yourself the message FFFFFFFFFFFFFFFFFF) collapse into the valid one.
No, it doesn't. Even if we will be able to communicate instantly (0 delay = infinite faster than speed of light), we will not be able to send a message to the past (negative delay).
Read the numerical example on https://en.m.wikipedia.org/wiki/Tachyonic_antitelephone
2) It's an unsolved problem, which waits for a correct solution.
3) Next time, please read what you are posting, please.
2) It's an unsolved problem because it's built on a foundation which is also an unsolved problem -- namely faster than light travel/communication. If -- if -- we solve the problem that it's built on, all indications are that sending a message to your past will become possible.
That being said, I expect that it's impossible because I expect that FTL travel/communication is impossible.
I'll add: 3) yes I read it. It's an example Einstein created, so possibly worth responding to the points made there rather than attacking me for "not reading it".
So you put in the numbers in the same way as that numerical example on Wikipedia, and it shows the same thing.
Edit: the only exception I can think of is if causality can be reversed.
2) It's an unsolved problem because formula is defined for [0..c] only and for EM communication only. For a•v = c² it predicts dT=0, so time will stop for unshielded Alice, like it stops for photon, so she will not be able to communicate at all. For a•v > c², the formula is not defined at all (it is the unsolved problem). In reality, we expect to see Cherenkov radiation. In theory, according to this formula, EM processes should go in reverse, which is not possible at all, because it requires all photon emitted by Alice to reverse their direction and hit Alice at her new location.
We're sitting here talking about how 1+2=3 and you're telling us that we're wrong, and that the sky is actually blue.
I have no basis to object to your argument, other than to tell you the thing you're arguing against clearly doesn't have anything to do with what the rest of us are talking about.
In a warp field, you're just somehow shrinking X,Y,Z while not doing the same to time. I see no reason to think you'd travel backwards in time.
Perhaps the CMB is the preferred frame of reference for all motion and this problem has a trivial solution (I am not a physicist), but everyone I’ve seen explain relativity starts with “there is no preferred frame”, and the rest follows.
According to §3.3, they aren't sure. If I parsed it correctly, they haven't mathematically resolved whether closed timelike curves are necessary, or precluded, or neither.
If not then the spacecraft is traveling faster than 'c' with regard to everything not in its reference frame (right?). If this kind of thing is possible then the universe is considerably weirder than we thought even after a hundred years or so of QM.
Any contradiction would be resolved on quantum level even if it can be interpreted at macroscopic scale as breaking of causality.
The important thing for physics would be to better clarify what time is. Why is the speed of light as much as it is, why is there time dilation related to mass and why is the time slowing down for objects travelling faster.
My guess is that the quantum world needs more of its own time to agree when there are more objects (more mass) close to one another, or that a fast travelling object needs to "agree" with its surrounding more frequently, and that overhead is manifesting as slowing of its time.
It's not unusual for (anticipation of) future events to affect the present. For example if I think it will rain, I grab an umbrella. While typically my belief that it will rain is based on something in the past (previously weather patterns for example), does it really change anything if a time traveler claiming to be me from the day after tomorrow told me it's going to rain tomorrow?
We only think of causality as going from past to future because that is the way we live. We also find the idea that particles can have an indeterminate location or pop randomly into or out of existence is weird, because our minds which have evolved to experience and understand the macroscopic world have no method of really processing that, but our intuition is not reality. If we can accept that our concept of position of objects in space is merely an approximation of a more complicated reality, the same for position of events in time should not be much harder.
People get bent up about paradoxes, but we have things like the Novikov self consistency principle [0] which allow us to avoid paradoxes even without one way causality.
[0] https://en.wikipedia.org/wiki/Novikov_self-consistency_princ...
(1) We are wrong about the nature of the universe and strong theism / creationism or the simulation hypothesis (which is the same thing more or less) are right.
(2) Life or complex life are so phenomenally unlikely that we are literally the only example in the local galactic supercluster at least, if not the whole universe. Speaking of creationists they often argue that the probability of life forming from non-life is insanely low. Maybe they're right about those probabilities and it only happened once.
(3) We live in a cosmic cemetery. There is a big nasty great filter ahead of us, and nobody has passed so far. Maybe the great filter is when you try to actually build FTL and cause a space-time catastrophe.
(4) We live in a "dark forest" and should be very, very quiet. Shhhhh....
(5) We live in a nature preserve. See #6.
(6) Last but not least, at least some UFOs really are ETs in which case there is no Fermi paradox. They're here and we have seen them. They're just laying low and not making overt contact.
My money would be on 6. If we demonstrated some kind of engineerable FTL I'd take the possibility that at least a few UFOs are ETs very seriously.
This reminds of an interview I read with Donald Knuth about the P vs. NP problem. IIRC, Knuth said he believes there probably is a polynomial time algorithm to solve NP problems, but the constant factor will be so absurdly huge (e.g. Graham's number) that it could never be run on an actual computer. I've heard layman claim that if P=NP were proven, then it'd suddenly spell the end of encryption relying on NP problems, but it's entirely possible that it'd have no practical impact. The constant factor is analogous to energy requirements for FTL.
This paper does not offer an engineerable solution but it does argue that negative mass, which may not exist, may not be required. That brings us closer. Are there solutions that require less energy? Are they physical or just math artifacts? Get the energy down to LHC levels and it becomes testable if even at submicroscopic scale. Show it at any scale and it’s a physics revolution and front page news and loads of money starts being spent.
Going to the moon was once dismissed by many scientists as requiring silly amounts of energy until we figured out a bunch of things like modern rocket engines and staged rockets.
No, it doesn't really do anything to weaken the threshold.
If humans discover a method of warp travel which is then validated by peer review, this does not do anything to increase the reliability of claims made by the US Air Force concerning the existence and performance characteristics of UAPs.
The reliability of the later claims are limited by the fact that there is no independent observation and verification from non-military sources, and due to the fact that former USAF employees such as Richard Doty have claimed they were hired to fabricate and provide false information to independent UFO researchers as part of a domestic counter-intelligence operation.
My point is that if a theoretical model for a warp drive emerges that provides falsifiable hypotheses in terms of what an external observer ought to see, this could be a useful tool for scientists to use if/when they are given the underlying UAP data I expect to see the government hand over the next 12-18 months.
The threshold I am referring to is when the theory becomes cohesive enough to provide such a tool for being able to generate such explanations, as opposed to the threshold where it could lead to actual applied physics.
0: Soliton - A "single bump" wave that propagates. See youtube for examples in water. These are (well-studied) solutions to the wave equation. In spacetime, we want some local "warp bubble" bump that is capable of moving/propagating around.
1: Negative energy density: Colloquially, this is like requiring negative mass. Nobody knows if this exists; most aren't hopeful.
2: Nice pun.
3: Positive semi-definite energy: I.e. non-negative (>=0)
4: So we're still talking mass-energies of Jupiter-(ish)-sized planets
This is very cool stuff. Definitely going to read the whole paper after work. Current questions:
- Is this really superluminal? Famously, the Alcubierre "warp bubble" solution doesn't actually propagate you superluminally unless you start it off that way.
- Is there a Minkowskian interior? The warped part of space is like your engine. We also need to have it carry around some flat space if we want it to be capable of carrying passengers.
- Can we construe this into PoC tests? How much energy do we need to detect warping (e.g. laser deflection) with current tech? Could some large-scale LIGO-like setup achieve detection?
Curious if I read this right tho.
This could serve as a method of generating acceleration without modifying the total energy on the hypersurface. One could start with a finite energy distribution highly concentrated and uniformly distributed in a spherical shell around a spacecraft. The energy density is then increased behind the spacecraft and decreased in front, without destroying or creating any additional energy. This increases the shift vector magnitude in the region where the spacecraft is located, transporting it to non-zero speeds relative to faraway observers. If the energy density is sufficiently concentrated behind the central observer, the relative speed becomes superluminal. This then operates as a tuneable solitonic configuration capable of superluminal speeds.
I mean with lines like "A geometrical interpretation of the Eulerian energy is found, shedding new light on superluminal solitons generated by realistic energy distributions" I'm still not sure it wasn't...
> A modest numerical analysis is carried out on a set of example configurations, finding total energy requirements four orders of magnitude smaller than the solar mass.
Can someone smarter than me say whether this is within the (reasonable-ish?) realm of matter-antimatter reactions? Like Star Trek!? 4 orders of magnitude less than the sun's mass does sound like a positive development - still a lot but less than before, right?
If this paper is correct, it brings the requirements down to a tenth of Jupiter's mass, which is probably somewhat achievable for a type I civilization. The Enterprise would be the size of a small gas giant to hold an equivalent amount of matter and antimatter. It'd be able to enter warp once.
...why once? Are you assuming all matter+antimatter is destroyed in the single trip? If you have x amount of critical material, could you not warp for half the distance of the "fuel" in your "tank" and then come back?
IANAPhyicist. I'm assuming that if we have the ability to contain and harvest energy from a matter/antimatter reaction then we also have the ability to stop it & start it at will.
Best case scenario we're talking a mass effect style planetary megastructure that forms a warp bubble around a ship and shoots it with just enough "momentum" for the warp bubble to fail right at the destination.
This drive needs a planet's mass in the form of pure energy, that's a totally different league. Also you dint have a planet to live on after that.
This is a major stretch for even a type 2
That’s something like 10^43 joules. Still not achievable anytime soon.
After all, if it was easy then everyone would be doing it.
Maybe it is feasible to build an FTL engine, but maybe it can only feasibly go at like 4c. That doesn't make it very easy to drop by our solar system and have a look at what all that radio noise means, even if anybody's heard it.
I wonder what the gradients look like.
So turn one of those into energy and you're good to go.
Not to be a broken record (there's some new variation on some old idea like every week it seems), but I'm firmly in the camp that believes FTL isn't possible. There are two prongs to that.
1. Theoretical: a lot of these theories rely on people not understanding the domain of a function (eg plugging in negative mass or energy into an equation; just because a function can operate over real numbers doesn't mean real numbers are the domain of that function); and
2. The macro evidence in that if FTL were possible it makes it that much more unlikely that we haven't detected starfaring life. Specifically, the potential volume of spacetime goes from a line cone of several million light years to the entire Universe (not just the observable Universe). We don't know how big that is of course but it's may orders of magnitude larger.
So this paper tries to "solve" the negative energy/mass problem. I honestly can't speak to the soundness of this idea. I am however skeptical.
https://www.dni.gov/files/ODNI/documents/assessments/Prelima...
I think breakthrough or disruptive technology are the key words here. They may not have said “beyond” but pretty much said everything short of that.
I don't think this is a great argument. Even with FTL the galaxy (not universe) is huge. Let's just say you can go 2x (warp factor 1.25) it would still take more than 2 years to reach Alpha Centauri (our closest star, 4.37 lyr). Even at 8c (Warp 2) it would still take >6 months. At 100c it is 2 weeks. The energy to travel these different speeds presumably does not scale well and so the difference between 2c and 1000c is going to be different level of civilizations[0]. The Milky Way is 2 million light years in diameter. There's about 1000 stars within 50 light years. Here's a list of stars <5 parsecs (16 lyr)[1] or within 5 days at 1000c or 0.0008% of the Milky Way. There could be extensive networks of trade and travel with FTL civilizations and we'd probably never detect them. These routes would still be fairly local and if they aren't around us then we would have no chance of seeing them. This is basically peoples in the Western Hemisphere trying to observe people in the Eastern Hemisphere when neither civilizations have the ability to cross the ocean nor see across it to a reasonable resolution.
I think a lot of people miss how huge the galaxy is (let alone Universe). Nothing is accessible without FTL. FTL is _necessary_. That, or immortality, or generational ships. The problem is that these numbers are so incomprehensibly large that we think they are magnitudes smaller than they actually are.
However big you think the galaxy is, it is actually bigger.
[0] https://en.wikipedia.org/wiki/Kardashev_scale
[1] https://en.wikipedia.org/wiki/List_of_nearest_stars_and_brow...
Assuming exponential growth, an alien civilization could easily have populated the galaxy. Or heck, octopuses are pretty smart and have been around for 150 million years, if they were land animals and figured out fire they'd probably rule the galaxy already.
We thought it was an aberration of mathematics when Einstein's equations blew up into singularities. A singularity couldn't exist in the real world, they said. Must just be an artifact of us using "real numbers", and we needed to be careful to respect the domains of those functions.
Well, turns out singularities do exist and the math led us right to them.
However, you do need a very high energy density, strong enough to create a black hole. And there is, of course, no guarantee that such an energy source is feasible or even possible. But you no longer need exotic matter — you just need enough regular matter in one spot.
What exactly is the breakthrough that has led to this recent spurt of warp drive papers? As far as I can tell the results are all purely theoretical and just re-arranging equations. None of them appear to rely on any recently lab discovered physics. Why couldn't this have been done in 1950, I wonder?
By "recent", you have to go back almost 30 years to the Aclubierre Drive (https://en.wikipedia.org/wiki/Alcubierre_drive) described in 1994. It forms part of the "we can come up with some interesting solutions to general relativity" literature.
That literature is not just a recent phenomenon. Research into theoretical wormholes (https://en.wikipedia.org/wiki/Wormhole#Development) goes back decades further.
It really is.
It's not like these are entirely new questions, but they used to be relegated to much smaller circles.
Hell, even recall any theoretical physics notions in other threads on HN and watch it burn.
It definitely seems like a bit of a philosophical change is sweeping throughout society, and it's probably mainly do to the increased speed and spread of information. It's easy to ignore, but those who don't are sort of forced to revaluate their world view and even their understanding of reality.
We have mainstream philosophers and neuroscientists giving talks on the limits of our perceptions in language "lay" people can understand. It's an interesting time to follow these developments.
It's almost like a new-age open-mindedness without the woo-woo. It was probably never really true, but growing up it felt like the answers were all written, and the universe was sticks and stones and the suggestion of anything else was nonsense. It seems more open now, and more intellectually encouraging, isn't it?
"No amount of modification to the configuration could get rid of these WEC-violating regions."
If I'm reading this correctly, all they have done is found a solution that has positive Eulerian energy density according to one particular reference frame, but not according to other reference frames. (I'm not a physicist, so please correct me if I'm wrong.)
In other words, if you wan to travel 100 light years, you must first spend more than 100 years warping the spacetime towards the destination, then you can move FTL.