Gravity: You’re interested in PBS video link
http://www.atlasoftheuniverse.com/12lys.html
Wolfram, Oligons https://www.sciencenews.org/article/stephen-wolfram-hypergraph-project-fundamental-theory-physics
Not really science, but the are-we-living-in-a-simulation logic refuted: https://news.ycombinator.com/item?id=23008373 via https://news.ycombinator.com/item?id=23007321 re paper
The aesthetics of science fiction spaceship design You have this PDF
SETI comments, talk of Dyson Swarms
Pluto https://solarsystem.nasa.gov/resources/933/true-colors-of-pluto/
Also: historical dictionary of science fiction via ars. Starship, 1882/1926. Shields as in protective force field, 1933
Scalar field energy and other infinite universe stuff.
Warp drives https://boingboing.net/2021/04/01/scientists-may-have-figured-out-how-to-make-a-warp-drive-work.html
Very credible navy pilot describing Tic Tac UFO encounter
Could a super species have spread to all galaxies when they were closer together? Probably not. Life was not possible 12 billion years ago because there weren't enough heavy elements.
Fermi paradox https://news.ycombinator.com/item?id=27205742
Tradition of FTL tech in fiction linked to Spacewar! via "Bergenholm Gyros"
Cartesian science – which indeed is a good science – says that the laws of physics cannot be violated and above all that such laws involve only matter and energy as we know them (and we know them extremely well). Mind and consciousness cannot interact: “res extensa” (matter) and “res cogitans” (mind) are two totally separated entities according to Cartesius. This paradigm didn’t change at all in about four centuries, and Cartesius constitutes one of the basic pillars of our fundamental science. And that is not that bad, apparently.
https://arstechnica.com/science/2022/05/how-to-build-a-wormhole-in-just-3-nearly-impossible-steps/
Story Relevant Comment - solves Fermi too.
Remember that time in the Lord of the Rings lore when the dwarves of Moria dug too greedily and too deep, unearthing the Balrog, an ancient horror not meant to roam free in the modern age?
Cosmic strings are kind of like that but for physics. They are hypothetical leftovers from the momentous transformations experienced by our Universe when it was less than a second old. They are defects, flaws in space itself. They’re no wider than a proton, but they may potentially stretch across the observable volume of the Universe. They have unspeakable powers—the ability to warp space so much that circles around them never complete, and they carry enough energy to unleash planet-destroying levels of gravitational waves. They’re also the path into some of the most exotic physics known (and unknown) to science.
But perhaps the greatest power cosmic strings possess is their capacity to confound physicists. According to our best understanding of the early Universe, our cosmos should be riddled with cosmic strings. And yet not a single search has found any evidence for them. Figuring out where the cosmic strings are hiding, or why they shouldn’t exist after all, will help push our understanding of cosmology and fundamental physics to new heights.
And no, we won’t need a wizard.
Let’s turn the clock back to some of the earliest moments in the history of the Universe. At that time, the cosmos was less than a fraction of a second old, and its entire observable volume, currently around 90 billion light-years across, was compressed into a space no bigger than an atom.
I’ll tell you straight away that we have no firm understanding of the nature of the Universe at this time. That’s because the matter that filled the Universe was in such an extremely exotic state, with temperatures and pressures so stupidly high, that it’s not even worth typing out numbers for them. At these energies, our current knowledge of physics simply breaks down. We have no well-understood equation, no guiding principles, no experimental results that can tell us what exactly the Universe was up to when it was so young.
But we do have a few sneaking suspicions. We’ve identified through our mathematical models and verified through experiments that the forces of nature aren’t always what they seem. At the normal, typical energies of everyday life, we experience four fundamental forces: gravity, electromagnetism, strong nuclear, and weak nuclear. But at high energies, things shuffle around a bit.
At an energy of around 246 GeV, the electromagnetic and weak nuclear forces cease to be distinct. Instead, they merge into a single super-force known (appropriately) as the electroweak force. And here's something wild: At those energies, there are only three forces of nature, not four. Once you drop below that energy, the electroweak force breaks apart into the more familiar electromagnetic and weak nuclear forces.
In physics, this splitting is called "spontaneous symmetry breaking." The unified electroweak force exhibits a deep mathematical symmetry, but that symmetry can only be sustained at high energies. In our everyday experience, that symmetry is hidden (or broken), and the electroweak’s two component forces appear to be wildly different, even though they’re really manifestations of a deeper, singular force.
Why stop there? Physicists suspect that at even higher energies, the strong nuclear force joins the party, creating a single force known as a GUT—a Grand Unified Theory. This isn’t mere idle speculation. The constants that define the strengths of the forces change with energy, and at high enough energies, they all have roughly the same strengths, signaling that unification is a viable option. Beyond that, at almost unfathomable energies, gravity is also thought to join with the others to create a Voltron of fundamental physics: a Theory of Everything.
The main challenge is that we don’t have a GUT, let alone a Theory of Everything. We have candidate theories, like supersymmetry, to provide a GUT, but they've come up short in experimental searches. String theory goes one step above to handle everything, but we’re not even sure how to test that. This means we lack the sharp mathematical insights needed to cut through the fog of the extremely early Universe, when the symmetries governing the fundamental forces remained unbroken.
Until they didn't, that is.
As our Universe expanded and cooled, it went through radical phase transitions, with the four forces of nature splintering off from unification one by one. And we suspect that during one of these phase transitions, cosmic strings were born.
When a physical system undergoes a phase transition, there’s a loss of symmetry. For example, a pencil balanced on its tip is in a high energy state and also beautifully symmetric—it looks the same from any angle of observation around it. But the perfectly balanced pencil is unstable; when it falls over, the symmetry breaks, with the pencil “choosing” a place to fall on the table below it. For the physics of that particular system, it doesn’t matter where the pencil falls—it could fall either to the left or the right, for example. The precise place where the pencil lands is arbitrary and doesn’t affect the larger picture, which is that the pencil is now in a more-stable, lower-energy, less-symmetric state.
When our Universe underwent the phase transitions into lower-energy states, with the forces of nature split off from each other, there was a similar freedom to choose exactly how to break those symmetries. The “direction” of the symmetry breaking (accounted for by a mathematical term that doesn’t affect the underlying physics) is totally arbitrary and is chosen randomly. And for the most part, it doesn’t matter.
But let’s look at another analogy to see why it sometimes might. Liquid water has more degrees of freedom—more symmetry—than a rigid block of ice. When water begins its phase transition and freezes, the molecules of water have to decide which direction to start building its crystal lattice. In other words, the water must break its fundamental symmetry when it reaches a lower-energy state, but the way that symmetry is broken is indiscriminate. The ice crystals could form in a left-right direction, for example, or just as equally in an up-down direction (I’m simplifying how ice crystals form, of course, just to move past this analogy as quickly as possible). It doesn’t matter which direction the water molecules choose; either way, you get ice.
But what if one part of the water starts freezing in an up-down direction, while another part of the water starts freezing in a left-right fashion? Eventually, you’ll have two sets of water molecules arranged in different orientations. Where these two sets meet, there will be a domain wall, a boundary between the two regimes that appears visible to us as a crack or flaw in the ice-cube. Go ahead, open your freezer and check it out: broken symmetries made manifest.
This can happen with any phase transition, including the ones in the infant Universe that triggered the splintering of the forces. Different regions of the Universe could have broken their symmetries in different ways. No matter what, throughout the Universe, you get the same fundamental forces operating in the same way, but those little mathematical terms that don’t affect the physics can take on different values from place to place. Just as in ice, when those regions meet, you get cracks. Defects. Flaws in spacetime itself.
Cosmic strings can take on various hypothetical properties depending on exactly which phase transition spawned them and how that particular phase transition played out. But all cosmic strings share one thing in common: tension. A lot of it.
A cosmic string is a flaw in spacetime, a blemish in the fabric of the Universe. Cosmic strings pull and pinch on spacetime all along their lengths, like creases in a piece of paper. This creasing manifests as a deficit in the usual amount of spacetime around an object. If you circumnavigate a pencil, the circle you draw will add up to 360 degrees. That’s kind of the definition of a circle. But if you circumnavigate a cosmic string, the space around it is so distorted that when you complete your journey and return to your starting point, you'll find that you traveled less than the usual 360 degrees.
In general relativity, you can’t bend spacetime without a source of mass or energy. In the case of cosmic strings, this energy comes from the enormous amount of tension built into the cosmic string itself. It is, after all, pinching two regions of spacetime together.
Tension is a form of energy, and if you get a lot of energy together, you get mass, so despite being made of nothing but spacetime itself, the strings have mass. The typical mass of a cosmic string depends on many theoretical factors, but a good rule of thumb is that a kilometer of cosmic string can outweigh the entire planet Earth.
In terms of dimensions, cosmic strings are likely no wider than a proton, although the precise size is governed by which phase transition triggered their formation. As to their lengths, well, that can be a bit complicated, as cosmic strings can lead very interesting lives.
Because cosmic strings are where two regions of the broken Universe meet, and that same Universe continually expands, at a first approximation, cosmic strings simply span the entire observable Universe. But strings are also dynamic, and if the Universe can produce one string, there’s no reason it can’t produce an entire network of them.
When cosmic strings intersect, they split each other at the intersection point, breaking larger strings into smaller ones. Occasionally, a string can loop around itself—when that happens, the loop rifts off, wandering away and leaving a shorter parent string behind.
So a collection of strings born in the early Universe may quickly evolve into a network of cosmos-spanning lengths, shorter segments, and free-floating loops.
In fact, it was just a few decades ago that cosmologists thought that such a cosmic string network provided the backbone for the large-scale structure of the Universe. At the very largest scales in the cosmos, galaxies form clusters and superclusters in a web-like pattern known as… well, the cosmic web. The cosmic web vaguely looks like a network of strings, so cosmologists openly wondered if the two were linked. Early in the history of the Universe, the thinking went, the cosmic strings generated the slight gravitational pull that would allow matter to accumulate near them, creating a skeletal framework that would eventually give rise to large collections of superclusters.
Alas, further analysis of the cosmic web and detailed images of the cosmic microwave background—the afterglow light pattern generated when our Universe transitioned from a plasma to a neutral state when it was 380,000 years old—ruled out the contribution of cosmic strings. Those kinds of networks just didn’t have the right kind of statistical properties to explain the distribution of matter at large scales.
But there might be other ways to find cosmic strings. One is through direct, simple observation. Massive objects bend the path of light. Like looking in a funhouse mirror or through a distorted piece of glass, we can see multiple images of the same background object. Take, for instance, clusters of galaxies. We routinely see background galaxies appear in multiple places, the light from a single source twisting, contorting, and repeating in fanciful ways.
Searches for giant cosmic lightsabers sweeping through the Universe haven’t found anything. If a cosmic string sits between us and a distant galaxy, we will see two copies of the same image, split by the gravity of the string. Sadly, extensive efforts to find such double-images have come up empty.
It likely goes without saying that you don’t want to encounter a cosmic string up close and personal; with that amount of tension, density, and energy, it could simply cut through you like a hot knife through butter. Since searches for chopped-up stars and planets will probably not be fruitful (because we have no idea what would happen and hence what to look for), we have to find other ways that strings interact with the Universe around them. There are many ways that strings can potentially couple to the Standard Model of particle physics: They might directly emit electromagnetic radiation, or they might spawn short-lived massive particles that then decay into showers of photons, neutrinos, antiparticles, and more. Depending on the theory backing them, cosmic strings may glow in all sorts of ways. But once again, searches for giant cosmic lightsabers sweeping through the Universe haven’t found anything.
The last-ditch effort to find evidence for cosmic strings is through gravitational waves. A single, straight cosmic string won’t emit gravitational waves, but when two strings meet (or when a string crosses over itself), the pinch at the point of intersection forms a cusp. This cusp travels down the length of the string at nearly the speed of light, emitting a burst of gravitational waves in the process (and, in some models, a beam of radiation or high-energy particles along with it). While unbroken string segments can last basically forever, loops of strings wiggle furiously, emitting tremendous amounts of gravitational waves as they shrink and eventually disappear.
Since the hypothetical string network, born in the early Universe, has undergone billions of years of pinching, looping, and wiggling, a portion of all the gravitational waves currently washing over the Earth should be caused by them. But once again, after decades of searching, there’s been no conclusive signal—not from the sharp burst of a traveling cusp, not from the general background hum from disintegrating.
What’s going on? Cosmic strings appear to be a generic prediction of our (admittedly fuzzy) understanding of the early Universe. We may not know exactly what went down all those billions of years ago, but we’re fairly certain that it involved phase transitions and that those phase transitions should support the existence of topological defects like cosmic strings.
And even though cosmic strings initially had nothing to do with their cousins, the strings found in string theory (which were deliberately called superstrings to set them apart from cosmic strings), recent theoretical work has found that in some cases, superstrings can grow from sub-Planckian lengths to gargantuan sizes, becoming cosmic strings in the process. A confirmed discovery of cosmic strings may well lend credence to string theory itself.
So we’re in a situation where we strongly suspect that there should be cosmic strings riddled throughout the Universe. And yet decades of direct and indirect searches haven’t found any. At all. We’re left with two conclusions. Either our understanding of the physics of the early Universe is way off base and cosmic strings aren’t nearly as generic as we think they are, or we’re not understanding how cosmic strings manifest themselves in the modern-day cosmos and our observations are missing something.
Or both. Both is definitely an option. Feel free to insert your own strings-twisted-in-knots pun here.
nytimes article on black holes and the holographic principle
Wormholes are Eistein-Rosen bridges (Nathan Rosen).
Hooft and Susskind - maybe black holes encode info like holograms.
Bekenstein - Hawking rival who set limit on amount of info that can be encoded in a volume. 10^-33 (Planck length).
“This is what we found out about Nature’s bookkeeping system,” Dr. ’t Hooft wrote in 1993. “The data can be written onto a surface, and the pen with which the data are written has a finite size.”
Ahmed Almheiri, a physicist at N.Y.U. Abu Dhabi, noted recently that by manipulating radiation that had escaped a black hole, he could create a cat inside that black hole. “I can do something with the particles radiating from the black hole, and suddenly a cat is going to appear in the black hole,” he said.
He added, “We all have to get used to this.”
Paul Sutter - 1/27/2023, 7:30 AM
Requiem for a string: Charting the rise and fall of a theory of everything Aurich Lawson | Getty Images String theory began over 50 years ago as a way to understand the strong nuclear force. Since then, it’s grown to become a theory of everything, capable of explaining the nature of every particle, every force, every fundamental constant, and the existence of the Universe itself. But despite decades of work, it has failed to deliver on its promise.
What went wrong, and where do we go from here?
Like most revolutions, string theory had humble origins. It started in the 1960s as an attempt to understand the workings of the strong nuclear force, which had only recently been discovered. Quantum field theory, which had been used successfully to explain electromagnetism and the weak nuclear force, wasn’t cutting it, so physicists were eager for something new.
A group of physicists took a mathematical technique developed (and later abandoned) by quantum godfather Werner Heisenberg and expanded it. In that expansion, they found the first strings—mathematical structures that repeated themselves in spacetime. Unfortunately, this proto-string theory made incorrect predictions about the nature of the strong force and also had a variety of troublesome artifacts (like the existence of tachyons, particles that only traveled faster than light). Once another theory was developed to explain the strong force—the one we use today, based on quarks and gluons—string theory faded from the scene.
But again, like most revolutions, whispers remained through the years, keeping hopes alive. In the 1970s, physicists uncovered several remarkable properties of string theory. One, the theory could support more forces than just the strong nuclear force. The strings in string theory had enormous tension, forcing them to curl up on themselves into the smallest possible volume, something around the Planck scale. Once in place, the strings could support various vibrations, just like a taut guitar string. The different vibrations led to different manifestations of forces: one note for strong nuclear, another for electromagnetism, and so on.
One of the possible vibrations of the string acted like a massless spin-2 particle. This is a very special particle because that would be the quantum force carrier of the gravitational force, the holy grail of a quantized theory of gravity. The theorists at the time couldn’t believe their chalkboards: String theory naturally, elegantly included quantum gravity, and they weren’t even trying!
The second big deal to come out in the 1970s was the introduction of supersymmetry, which claimed that all the particles that carry forces (called bosons, a category that includes photons and gluons) were linked to a supersymmetric partner from the collection of particles that build stuff (called fermions, like electrons and quarks), and vice versa.
This symmetry doesn’t appear in everyday settings; it only manifests at extremely high energies. So if you were to go back in time to the earliest moments of the Big Bang or had enough funding to build a particle collider along the orbit of Jupiter, you wouldn’t just see the normal zoo of particles we’re familiar with; you'd see all their supersymmetric partners, too. These were given suitably stupid names, like selectrons, sneutrinos, squarks, photinos, and my personal (least) favorite, the wino boson.
By making this connection, string theory could build a bridge from the bosons to the fermions, allowing it to leap from just a theory of forces to a theory of every single particle in existence. The introduction of supersymmetry also solved the nasty problem of tachyons by replacing those troublesome particles with supersymmetric partners, which was a nice flourish.
At the end of the 1970s, string theory could potentially explain all the particles and all the interactions among them and provide a quantum solution to gravity.
One theory to rule them all, one theory to find them, one theory to bring them all, and in the stringiness bind them.
It’s been almost half a century since physicists first realized that string theory could potentially provide a theory of everything. Despite decades of work involving hundreds of scientists over several (academic) generations and countless papers, conferences, and workshops, string theory hasn't quite lived up to that potential.
One of the biggest issues involves the way that strings interact with each other. A major pain in the asymptote when it comes to quantum theory is the infinite variety of ways that particles can interact. It’s easy enough to write down the fundamental governing equations that describe an interaction, but the math tends to blow up when we actually try to use it. In string theory, fundamental particles aren’t particles at all; they’re tiny loops of vibrating… well, strings. When we see two particles bouncing off each other, for example, it’s really two strings briefly merging and then separating. That sounds super cool, but there are still an infinite number of ways that process can unfold.
Unlike its quantum cousins, when it comes to string theory, we have no fundamental theory—we have only a set of approximation and perturbation methods. We’re not exactly sure if our approximations are good ones or if we’re way off the mark. We have perturbation techniques, but we’re not sure what we’re perturbing from. In other words, there’s no such thing as string theory, just approximations of what we hope string theory could be.
The second major difficulty involves the vibrations of the strings themselves. Early on, physicists realized that the strings had to vibrate in more than three dimensions of space if they were to explain the full variety of forces and particles in the Universe. 3D was just too limiting; it constricted the number of potential vibrations so severely that it was no longer a theory of everything, just a theory of some things, which isn’t nearly as exciting.
The earliest versions of string theory needed 26 spatial dimensions, but after supersymmetry and some dimensional layoffs, theorists were able to slim that number down to “only” 10.
Now, the Universe doesn’t have 10 spatial dimensions, at least on large scales, because we would have noticed them by now. So all the extra dimensions have to be tiny and curled up on themselves. When you wave your arm in front of you, you’re traversing these tiny dimensions countless times, but they’re so small (typically at the Planck scale) that you don’t notice them.
The extra dimensions give the strings enough vibrational options to explain all of physics. And the variety of shapes those dimensions can take as they curl up on themselves are known as Calabi-Yau manifolds. If you curl a piece of paper up on itself, you have a few choices: you can connect just one pair of edges (a cylinder) or both pairs (a delicious doughnut), you can introduce one flip (a Mobius strip) or two (a Klein bottle), and so on. That’s only two dimensions. With six, you have somewhere between 10,500 and 1,010,000 possible options. We care about all these possible shapes because the way the extra spatial dimensions curl up determines the possible set of vibrations of the strings—each shape produces a different set of string vibrations, like different musical instruments. A tuba sounds different from a saxophone because of the way it’s structured and the kind of vibrations it can support. But our Universe is only a single instrument (an oboe, perhaps) with a single set of “notes” that correspond to our suite forces and particles.
So which one of the zillions of potential Calabi-Yau structures corresponds to our reality? We don’t know. Because we don’t have a full accounting of string theory, only approximations, we don’t know how the shape of the curled-up dimensions affects the string vibrations. We have no reliable machinery that goes from a given Calabi-Yau manifold to the physics that appears in that universe, so we can’t run the reverse operation and use our unique experience of physics to discover the shape of the curled-up dimensions.
It gets worse. By the early 1990s, string theorists had developed not one, not two, but five different versions of string theory. The variations were based on how a fundamental string was treated. In some versions, all strings had to form closed loops; in others, they could be open. In some, the vibrations could only travel in one direction; in others, they could travel both, and so on. For the curious (and those eager for edgy names for your kids) the five string theories are Type 1, Type IIA, Type IIB, SO(32) heterotic, and E8xE8 heterotic.
So now we have a slight embarrassment of riches. Five potential theories, all claiming to be the best approximation of the true string theory. That’s pretty awkward, but in the 1990s, physicist Edward Witten declared a winner: all of them.
He discovered dualities, which are mathematical relationships between theories that allow you to transform one to the other. In this case, Witten tied the five string theories into a single knot. This idea has yet to be mathematically proven, but it indicates that the five string theories are really manifestations of a single, unified-for-real-this-time string theory, which Witten called M-theory. We don’t know what M-theory is—or even what the “M” stands for (my vote is “Manchego”)—but it should be the actual string theory.
That’s potentially very useful since once we determine whether our approximation schemes are valid, all the five versions of string theory should converge on it, and our Universe should pop out of the math.
But that was almost 30 years ago, and we still don’t know what M-theory is. We still haven’t figured out a solution for string theory.
To be clear, our inability to understand string theory isn’t limited by experiment. Even if we could build a super-duper-collider experiment that achieved the energies necessary to unlock quantum gravity, we still wouldn’t be able to test string theory because we have no string theory. We have no mathematical model that can make reliable predictions, only approximations that we hope accurately represent the true physics. We can test those approximations, I guess, but it won’t help us determine the inner workings of the true model.
Even so, the experiments we do have aren’t exactly helping. When supersymmetry was developed by the string theory community in the 1970s, it proved to be such a popular idea that many particle physicists took it as their own, using those techniques to develop models of high-energy physics beyond the Standard Model.
Supersymmetry isn’t a single theory; it's a family of theories. They all share the same core principle: that bosons and fermions are partners of each other at high enough energies. But the details of the interactions are left as a homework exercise for each individual theorist. Some supersymmetric theories are relatively (and that’s putting a lot of work on the word) straightforward, while others are more complex. Either way, in the 1990s, physicists became so convinced the supersymmetry was super-terrific that they devised a super-powerful collider to test it out: the Large Hadron Collider.
The beams of the LHC began their first test operations in 2008 with two main science goals in mind: finding the elusive Higgs boson and finding evidence of supersymmetry.
Four years later, the Higgs was found. Supersymmetry was not. It’s now 15 years later, and there are still no signs of supersymmetry.
In fact, all the “easy” versions of supersymmetry have been ruled out, and many of the more complicated ones, too. The dearth of evidence has slaughtered so many members of the supersymmetric family that the whole idea is on very shaky ground, with physicists beginning to have conferences with titles like “Beyond Supersymmetry” and “Oh My God, I Think I Wasted My Career.”
Where does that leave string theory? Well, since (and I’ll never stop reminding you of this) there is no string theory, only approximations, it’s not quite pining-for-the-fjords dead yet. It’s possible to build a version of string theory without using supersymmetry… maybe. The math gets even thornier and the approximations even sketchier, though. Without supersymmetry, string theory isn’t gone, but it’s certainly on life support.
After 50 years of work on a theory of everything, we’re left with approximate theories that seem so tantalizingly close to explaining all of physics… and yet always out of reach. Work continues on finding the underlying dualities that link the different versions of string theory, trying to suss out the mysterious M-theory that might underlie them all. Improvements to perturbation theory and approximation schemes provide some hope for making a breakthrough to link the dimensional structure of the extra dimensions to predictable physics. Routes around the damage caused by the LHC’s lack of evidence for supersymmetry continue to be laid.
In response to our inability to choose which Calabi-Yau manifold corresponds to our Universe—and more importantly, why our Universe has that manifold rather than any of the other ones—some string theorists appeal to what you might call the landscape. They argue that all possible configurations of compact dimensions are realized, each one with its own unique universe and set of physical laws, and we happen to live in this one because life would be impossible in most or all of the others. That’s not the strongest argument to come out of physics, but I’ll save a dissection of the idea for another day.
We don’t have a string theory, so we can’t test it. But it might be possible to perform experiments on string theory-adjacent ideas, and there’s been some progress on that front. Perhaps the event of inflation, which occurred immediately after the Big Bang, can teach us about string theory (or the formation of Universe-spanning cosmic strings). And perhaps there’s more to the dualities than we initially thought.
Recently, theorists have proposed another duality, the AdS/CFT correspondence. It’s not exactly string theory, but the idea is certainly sponsored by it. This correspondence proposes that you can write down a string theory in a special three-dimensional setting and connect it to a special kind of quantum theory on its two-dimensional boundary. In principle, the correspondence should allow you to transform your impossible-to-solve string theory problem into a merely really-difficult-to-solve quantum problem (or vice versa, allowing you to use some of the mathematical tools developed in string theory to solve your thorny quantum problem).
The AdS/CFT correspondence has found some limited applications, but its full utility remains unclear. And while the AdS/CFT correspondence has yet to be proven, theorists claim it should be possible soon (although they said the same thing about string theory itself during the Reagan administration).
Most string theorists of the modern era don’t work on string theory directly but instead mostly on the AdS/CFT correspondence and its implications, hoping that continuing to probe that mathematical relationship will unlock some hidden insight into the workings of a theory of everything.
I wish them luck.