"Then we can talk about building the first prototypes"
March 9, 2021 12:24 PM   Subscribe

Nothing like enthusiasm and self-belief when you're aiming for the impossible (and probably need to keep the funding flowing). Proxima Centauri - round-trip in eight years. Abstract talks about using existing science, and materials that already exist so that makes a nice change. Erik W Lentz, 2021. Breaking the warp barrier: hyper-fast solitons in Einstein–Maxwell-plasma theory, Classical and Quantum Gravity.

"This work has moved the problem of faster-than-light travel one step away from theoretical research in fundamental physics and closer to engineering. The next step is to figure out how to bring down the astronomical amount of energy needed to within the range of today's technologies, such as a large modern nuclear fission power plant [instead of thirty large nuclear power plants]. Then we can talk about building the first prototypes," says Lentz. Full text on arxiv
posted by unearthed (35 comments total) 16 users marked this as a favorite
 
Eponysterically posted.
Well done.
posted by armoir from antproof case at 12:54 PM on March 9, 2021 [5 favorites]


Having read the abstract, introduction, and bibliography of the preprint from arXiv, this paper seems to have a kook factor low enough to be worth reading carefully.
posted by fantabulous timewaster at 12:56 PM on March 9, 2021


"In addition, the solitons (warp bubbles) were configured to contain a region with minimal tidal forces such that the passing of time inside the soliton matches the time outside: an ideal environment for a spacecraft. This means there would not be the complications of the so-called 'twin paradox' whereby one twin traveling near the speed of light would age much more slowly than the other twin who stayed on Earth: in fact, according to the recent equations both twins would be the same age when reunited."
This is interesting, but is that really ideal? If you could make time pass slower for the people inside the spacecraft, wouldn't that be preferable, so they experience a shorter travel time (very important when the trip takes years, and would allow fewer supplies, etc.), even though they turn out to in the end be a year or two younger than some hypothetical twin?

(Otherwise, cool and fun research, though.)
posted by Joakim Ziegler at 12:56 PM on March 9, 2021 [1 favorite]


The article seems to say not that we're a factor of 30 away, but that we're 30 orders of magnitude away.
posted by paper chromatographologist at 12:57 PM on March 9, 2021 [8 favorites]


So it's like saying, "currently we need an ocean of water but, if we can get that down to a drop, we're in business." Except about 100,000 times worse than that.
posted by paper chromatographologist at 1:06 PM on March 9, 2021 [8 favorites]


So as soon as we figure out how to HARNESS THE SUN, we're in business.
posted by Faint of Butt at 1:11 PM on March 9, 2021 [1 favorite]


I'm harnessing the sun right now. It's powering my garden and warming my dogs.
posted by Splunge at 1:17 PM on March 9, 2021 [10 favorites]


So what we need is a captive black hole?
posted by Luddite at 1:18 PM on March 9, 2021


if it doesn't need a solar-system-length runway to get moving faster than our current rocket speeds, then being able to get a tiny fraction of light speed would do the trick for local travel. I'm convinced if we leave our solar system without the right permits there will be major fines.
posted by th3ph17 at 1:24 PM on March 9, 2021 [2 favorites]


So as soon as we figure out how to HARNESS THE SUN, we're in business.

Ringworld: the cause of, and solution to, all life's problems!
posted by lock robster at 1:26 PM on March 9, 2021 [8 favorites]


So as soon as we figure out how to HARNESS THE SUN, we're in business.

"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter."

The total energy output of the sun is about 4,000,000 tons every second. 100 times the mass of Jupiter is ~2 × 10^26 tons. At that rate, accumulating sufficient energy would require a mere 1.5 trillion years.

Barring almost unimaginable energy efficiency improvements, there would seem to be a catch-22 where powering this engine first requires visiting (and building Dyson spheres around) several hundred star systems. Or figuring out a way to turn the entire sun into pure energy at ~100% efficiency.

Good news: Interstellar travel is possible. Bad news: It's a one-way trip because you have to consume an entire star to get anywhere.
posted by jedicus at 1:36 PM on March 9, 2021 [6 favorites]


It's unclear to me whether or not the author of this article recognizes there's a difference between "very fast sub-light travel" and FTL.

First of all, you don't need FTL to get to Proxima Centauri in your lifetime. It's 4 light years away. If you can constantly accelerate at 1G, you can get there in 5 years.

Second, due to time dilation you can actually get to a lot of very far away places in your lifetime, even places that would take light a long time to reach.

Finally, if you can go faster than light in an external frame of reference, you can arrive whenever you want. Faster than light travel basically guarantees time travel (which is one of the reasons people think it's impossible, the lack of time travelers), so you can decide your journey takes no time, or even negative time if that works better for your schedule.
posted by justkevin at 1:46 PM on March 9, 2021 [6 favorites]


Even if this just takes FTL from “impossible” to “wildly impractical” that’s still y’know pretty cool
posted by ook at 1:48 PM on March 9, 2021 [5 favorites]


Ringworld: the cause of, and solution to, all life's problems!

Dyson Sphere or GTFO
posted by whuppy at 1:55 PM on March 9, 2021 [2 favorites]


Bad news: It's a one-way trip because you have to consume an entire star to get anywhere.

you know that eerie feeling you get when you realize you live inside a galaxy that is something else's gas tank?
posted by th3ph17 at 1:56 PM on March 9, 2021 [4 favorites]


Good news: Interstellar travel is possible. Bad news: It's a one-way trip because you have to consume an entire star to get anywhere.

Now *there's* a sci-fi premise worth exploring. Feels like it has shades of Liu Cixin.
posted by Johnny Assay at 1:56 PM on March 9, 2021 [1 favorite]


Good news: Interstellar travel is possible. Bad news: It's a one-way trip because you have to consume an entire star to get anywhere.

Good news: it’s extremely easy to tell where you’ve already been.
posted by notoriety public at 1:57 PM on March 9, 2021 [5 favorites]


Barring almost unimaginable energy efficiency improvements, there would seem to be a catch-22 where powering this engine first requires visiting (and building Dyson spheres around) several hundred star systems.

Oh, hai.

(Seriously, if you can stop look away from Valheim for a second for a game that has a mere 30,000 reviews and is also at "overwhelmingly positive," I highly recommend it.)
posted by The Bellman at 2:09 PM on March 9, 2021 [1 favorite]


you have to consume an entire star to get anywhere.

The Travelling Salesperson Problem appears again!
posted by clew at 2:17 PM on March 9, 2021 [3 favorites]


I mean, come on. There are a whole bunch of stars, is all I'm sayin'. No need to go all Cosmic Lorax here.
posted by Halloween Jack at 2:33 PM on March 9, 2021 [2 favorites]


If you’re going to start doing engineering calculations, this paper is a bad place. That’s not its point.

If you’ve never done an engineering calculation about interstellar travel before, you should do this one first (credit to the late Bob Park). Suppose that you, personally, want to go to Alpha Centauri. You’re desperate to go so you’re willing to make some compromises about the quality of the trip. You want to get there before you die, so budget forty years for your trip. Go in the smallest container that could fit you and be made vacuum-tight: perhaps it’s the size and weight of a passenger car. Assume you accelerate forward the whole time (so you’ll do a flyby, not stop) at a constant rate, and work backwards to figure out how much power you’ll need to convert into your kinetic energy via some thrust. Then look on the internet for pictures of nuclear power plants which give that much power, and start planning for how you’re going to fit them in your car with you. This unpleasant trip could be made using things that already exist, but it’s not clear if there’s any way to fit them together.

This is definitely about manipulating spacetime to create a timelike shortcut between two spacelike-separated events, in the style of a wormhole or an Alcubierre drive, and not just about going very fast. (A “soliton” in physics is a wave that keeps its shape as it travels, rather than splitting up into a wavetrain; this result and the Alcubierre result are “solitons of spacetime.”) One of the problems with those “mainstream warp drives” is that they require the existence of some material with negative energy density. That’s something you can do mathematically, but there isn’t any physical motivation for it at all: matter and energy have positive energy density. It’s like unicorn blood: a thing that would fit into our understanding of the world if it did exist, but it doesn’t.

According to the paper, when the first computations were done about Alcubierre warp bubbles, you didn’t just need negative energy / unicorn blood to sustain them: you needed more of the exotic material than there is normal matter in the entire universe1. Working with these models, the amount of necessary exotic matter has actually dropped by at least thirty orders of magnitude. That’s only medium-interesting, because it doesn’t matter how much of the stuff you need if it exists only in people’s imagination.

The result here is a Alcubierre-like soliton which requires only positive-energy matter. It may need a universe full of blood, but it’s no longer magic blood. Whether any of the energy-saving approximations from the negative-energy analogous system will carry over seems to be a future research project.

1Remind me later to start a band called “Universe Of Unicorn Blood.”
posted by fantabulous timewaster at 3:27 PM on March 9, 2021 [20 favorites]


So what we need is a captive black hole?

where we're going, you won't need eyes solitons
posted by banshee at 3:55 PM on March 9, 2021 [2 favorites]


First of all, you don't need FTL to get to Proxima Centauri in your lifetime. It's 4 light years away. If you can constantly accelerate at 1G, you can get there in 5 years.
imagining the size of the fuel tank you'd need to accelerate at 1G for 44,000 hours straight
posted by DoctorFedora at 6:55 PM on March 9, 2021


imagining the size of the fuel tank you'd need to accelerate at 1G for 44,000 hours straight

This is the reason why Bussard scoops figure prominently in hard sci fi stories.

It's really a matter of power (fusion, or antimatter) and a magnetic field.
posted by Flight Hardware, do not touch at 8:30 PM on March 9, 2021 [1 favorite]


Lentz explains, "The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter. The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.... Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude."

Let's assume, in very round numbers, that a nuclear power plant produces roughly 1 GW of power (109 watts). (And let's assume the drive draws power, as suggested by the invocation of nuclear reactors, rather than just using a fixed amount of energy.)

Bad News: The power required for the drive is 30 orders of magnitude larger than a nuclear reactor, or about 1039 watts. Oh no!

Good News: Proposed "energy-saving mechanisms" could bring that down by 60 orders of magnitude, to about 10-21 watts. That's about as much power produced by an electron falling down a one-volt potential about every three minutes. No problem!

So, in summary, the amount of energy required is somewhere between astronomical and infinitesimal.
posted by The Tensor at 1:35 AM on March 10, 2021 [3 favorites]


Would reconfiguring the main deflector array in some way help with this?
posted by thelonius at 2:20 AM on March 10, 2021 [7 favorites]


Good news: it’s extremely easy to tell where you’ve already been.

You would think so, but keep in mind that if you destroy Barnard's Star to travel to Sirius, you might still see the light from Barnard's Star when you get to Sirius because you got to Sirius faster than that light did.

Maybe. I don't know, my head hurts now.
posted by Johnny Assay at 6:40 AM on March 10, 2021


FTL is also a time machine in the sense that it there's a frame of reference where the traveller appears to arrive before they left. Worries about what that might mean have led many people to conclude it's impossible. It's always glossed over in SF which has FTL by ignoring relativity.
posted by pw201 at 6:41 AM on March 10, 2021


So, in summary, the amount of energy required is somewhere between astronomical and infinitesimal.

But that's only a rough estimate at best..
posted by DreamerFi at 6:44 AM on March 10, 2021


We were overjoyed when the Visitors began to arrive. They were so....Then, after each departure, we realized a star was missing from our galaxy. By the time we interpreted how to achieve their gift, the so-called Star Engine, the Visitor's monstrous vessel had gobbled up most nearby stars. Our choice is clear, now that it's too late. We can leave--go anywhere our math can direct us--but nothing in our solar system will be here when we return.
posted by mule98J at 7:16 AM on March 10, 2021 [3 favorites]


Worries about what that might mean have led many people to conclude it's impossible.

Kurt Gödel believed that time travel was possible, on the basis of some sort of cosmological theory he fooled around with for fun. But he thought that it would be impossible to shoot your grandfather etc. because this would be logically paradoxical. It just wouldn't work out. The gun would jam, the police would arrest you, a bus would hit you just as you took aim.
posted by thelonius at 7:40 AM on March 10, 2021 [1 favorite]


It's always glossed over in SF

Usually, not always. I can think of a few different SF universes with acausal FTL.
posted by GCU Sweet and Full of Grace at 8:03 AM on March 10, 2021


a frame of reference where the traveller appears to arrive before they left.

Me: *watching my spacecraft almost arrive at Proxima Centauri but explodes*

Also Me: "I think I'll stay here".

A WILD PARADOX APPEARED!
posted by AzraelBrown at 1:31 PM on March 10, 2021 [1 favorite]


First of all, you don't need FTL to get to Proxima Centauri in your lifetime. It's 4 light years away. If you can constantly accelerate at 1G, you can get there in 5 years.

Not if you have to start slowing down by 1G at the halfway point.
posted by hypnogogue at 5:03 PM on March 10, 2021 [2 favorites]


A space patrol 1G trajectory covering 4 light years would take 47.27 months.
posted by ob1quixote at 6:04 PM on March 10, 2021


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