In last weeks podcast,, our guest host, neurosurgeon Michael Egnor, interviewed idealist philosopher of science and physicist Bruce Gordon on how the quantum physics that underlies our universe makes much more sense if we have a non-materialist view of reality. Even then, it challenges our conventional view of how nature must work:

A partial transcript, Show Notes, and Additional Resources follow.

Michael Egnor: When I was in college, I was a biochemistry major and I took some courses in quantum mechanics. It was noted in the course that when you look at the most fundamental properties of subatomic particles, matter seems to disappear. That the reality of the subatomic particles is that theyre mathematical concepts. It utterly fascinated me that, at its basic structure, reality is an idea which fits very nicely with idealism. Dr. Gordon is an expert on idealism and on the philosophy of science. What do you think about all this?

Bruce Gordon (pictured): Well, certainly my own path to idealism was paved by my reflections on the metaphysics of quantum physics. So Im deeply sympathetic to the questions that youre raising.

Quantum physics is a highly mathematical theory that describes the nature of reality at the atomic and subatomic level. The mathematical descriptions of quantum physics have a variety of experimentally confirmed consequences that I would say preclude the possibility of a world of mind-independent material substances governed by material causation.

We live in a reality that seems very much to be described by classical Newtonian kinds of mathematical descriptions. However, at the most fundamental level thats not the case.

Note: Newtons Laws of Motion, formulated by Isaac Newton, describe in simple terms that can be rendered in mathematics the way objects and force behave in the visible world around us. For example, Newtons First Law can be phrased: objects tend to keep on doing what theyre doing (unless acted upon by an unbalanced force). Newtons First Law, (Physics Classroom).

No law of nature makes moving objects stop. They stop because forces act on them. Otherwise, they would just keep moving. Similarly, no law of nature makes still objects stay put. They stay put because no force is acting on them, causing them to move.

The world we can see around us works on these kinds of principles. But down at the level of, say, electrons, the types of rules followed while strict are quite different.

Bruce Gordon: Lets take a look at some interesting quantum experiments that point toward the mind-dependent character of reality Fundamentally, weve got a situation in which reality at the quantum level does not exist until it is observed. I think one of the most fascinating ones is the quantum eraser experiment.

When youre not observing reality, it seems to behave in accordance with the Schrdinger wave equation, and various relativistic expressions of that. But when you are observing it

Note: The Schrdinger wave equation is a partial differential equation that describes the dynamics of quantum mechanical systems via the wave function. Electrical4u.com The equation describes, using mathematics, what quantum systems do when no one is trying to measure them.

Bruce Gordon: So what does the delayed choice quantum eraser experiment do? Well, it tries to measure which path a particle would have taken after interference in the wave function has been created that is inconsistent with that particles behavior. So youve got a splitter of some sort. Its going to divide the quantum wave function and send it along two different paths. Then youre going to make a measurement along one of the paths to see whats happening.

That interference can be turned off or on by choosing whether or not to look at which path the particle has taken after the interference already exists.

Now if you dont look, you get an interference phenomenon at the end. If you do look, the wave function instantaneously collapses and you detect the particle along that pathway. So choosing to look erases the wave function and gives the system a particle history.

Bruce Gordon: This experiment has been performed under what would be called Einstein Locality Conditions. In other words, no signal could have passed subject to the limiting velocity of the speed of light between the components of the system to cause the effect that youre observing.

The very fact that we can make a causally disconnected choice of whether wave or particle phenomena are manifested in a quantum system essentially shows that there is no measurement-independent and causally connected, substantial material reality at the micro physical level. It is created by the measurement itself.

Michael Egnor: What counts as a measurement?

Bruce Gordon: What can count as a measurement is any sort of interaction that would localize the wave function and yield a determinant local result. That could involve a conscious observer, or it might not involve a conscious observer.

Michael Egnor (pictured): What sort of measurement wouldnt involve a conscious observer? Does it matter how much you pay attention? If Im a little preoccupied, do I not get much interference, but maybe a little? Because it really implies that there is an actual something that is observation and its an on or off thing, its yes or no. Theres no in between

Say, for example, that Im a physicist who is looking at a quantum system, and Im actually looking at the oscilloscope, or whatever our modern instrument is, when its happening. Everybody would say, Well, thats an observation for sure.

But lets say that Im not in the room and Im just taping it but I plan to look at it later. Is that an observation? If I change my mind and decide not to look at it, does that change the system?

Im fascinated by what we mean by an observation because in reality, an observation is a continuum. I mean, I could be watching something, then my mind wanders. Im thinking about lunch. Does that make the system go back into indeterminacy? Then it becomes determined again when I focus on it?

Bruce Gordon: Not necessarily, if youve got decoherence happening in the quantum metaphysics of the world around you. So how do we bring this into relationship with idealism?

In fact, I was going to talk about some other experiments to kind of further massage peoples intuitions with respect to the nature of the reality that undergirds these sorts of phenomena. Let me talk about at least a couple more. Then well come back to the question of, Whats going on when were not looking?

Michael Egnor: Right. Is the moon there if no ones looking at it?

Next: So is the moon there if no one is looking at it? Or is there no there there?

Here are stories from Bruce Gordons previous podcast with host Michael Egnor, where he defends idealism as a reasonable way of making sense of nature:

Why idealism is actually a practical philosophy. Not what you heard? Philosopher of science and pianist Bruce Gordon says, think again. Is reality fundamentally more like a mind than a physical object? Many are sure of the answer without understanding the question.

and

A physicist and philosopher examines panpsychism. Idealism says everything is an idea in the mind of God. Panpsychism says everything participates in consciousness (thus is not just an idea). Bruce Gordon thinks that, for a thing to be conscious, there must be something that it is like to be that thing. Can panpsychism demonstrate that?

Podcast Transcript Download

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In Quantum Physics, Reality Really Is What We Choose To Observe - Walter Bradley Center for Natural and Artificial Intelligence

Is our universe extremely unnatural, a weird permutation among countless other possibilities, observed for no other reason than that its special conditions allowed life to arise, or, are the properties of the universe are inevitable, predictable, that is, natural, locking together into a sensible pattern? This is the question, the great unknown, that preoccupies theoretical physicist Nima Arkani-Hamed, a professor at the Institute for Advanced Study (IAS) in Princeton, N.J.

Beyond Spacetime and Quantum Physics

Arkani-Hamed takes us past the edge, beyond Einstein, beyond space-time and quantum mechanics and the tropes of 20th-century physics, to a spectacular new vision of the cosmos. In 2012, he won the inaugural $3 million Fundamental Physics Prize for original approaches to outstanding problems in particle physics, including the proposal of large extra dimensions, new theories for the Higgs boson, novel realizations of supersymmetry, theories for dark matter, and the exploration of new mathematical structures in gauge theory scattering amplitudes.

The Participatory Universe

Arkani-Hameds preoccupation is the question that intrigued his predecessor, the great American quantum physicist John Archibald Wheeler in the last decades of his life was: Are life and mind irrelevant to the structure of the universe, or are they central to it? Wheeler originated the notion of a participatory, conscious universe, a cosmos in which all of us are embedded as co-creators, replacing the accepted universe out there, which is separate from us. He suggested that the nature of reality was revealed by the bizarre laws of quantum mechanics. According to the quantum theory, before the observation is made, a subatomic particle exists in several states, called a superposition (or, as Wheeler called it, a Smoky Dragon). Once the particle is observed, it instantaneously collapses into a single state.

The Shape-Shifting Cosmos Huge Clue to the Nature of the Ultimate Truth

Multiverse of Universes Beyond Our Reach

A natural universe is, in principle, a knowable one, writes Batrice de Ga in Quanta. But if the universe is unnatural and fine-tuned for life, observes Arkani-Hamed, the lucky outcome of a cosmic roulette wheel, then it stands to reason that a vast and diverse multiverse of universes must exist beyond our reach the lifeless products of less serendipitous spins. This multiverse renders our universe impossible to fully understand on its own terms.

Astonishingly Fine-tuned for Life

The known elementary particles, concludes Batrice de Ga, codified in a 50-year-old set of equations called the Standard Model, lack a sensible pattern and seem astonishingly fine-tuned for life leading Arkani-Hamed and other particle physicists, guided by their belief in naturalness, to spend decades devising clever ways to fit the Standard Model into a larger, natural pattern while particle colliders such as the Large Hadron Collider have failed to turn up proof of their proposals in the form of supersymmetry, new particles and phenomena, increasingly pointing toward the bleak and radical prospect that naturalness is dead.

The Doom of Spacetime

Today, many physicists feel trapped writes Natalie Wolchover in The New Yorker, and see the need to reformulate the theories of modern physics in a new mathematical language. They have a hunch, she writes, that they need to transcend the notion that objects move and interact in space and time. Einsteins general theory of relativity beautifully weaves space and time together into a four-dimensional fabric, known as space-time, and equates gravity with warps in that fabric. But Einsteins theory and the space-time concept break down inside black holes and at the moment of the big bang. Space-time, in other words, may be a translation of some other description of reality that, though more abstract or unfamiliar, can have greater explanatory power.

Beyond the Cosmos Worlds Utterly Unlike Anything We Can Imagine

Challenges Space and Time as Fundamental Components of Reality

In 2013, Nima Arkani-Hamed and Jaroslav Trnka discovered a reformulation of scattering amplitudes that makes reference to neither space nor time, rather they discovered that the amplitudes of certain particle collisions are encoded in the volume of a jewel-like geometric object, which they named the amplituhedron that dramatically simplifies calculations of particle interactions and challenges the notion that space and time are fundamental components of reality.

The amplituhedron, seamlessly connects the large- and small-scale pictures of the universe, could help by removing two deeply rooted principles of physics: locality and unitarity. Both are hard-wired in the usual way we think about things, said Arkani-Hamed. Both are suspect.

This discovery has led them to explore this new geometric formulation of particle-scattering amplitudes, hoping that it will lead away from our everyday, space-time-bound conception to some grander explanatory structure of reality.

The Unknown Question To Which the Universe is the Answer

To Arkani-Hamed, the laws of nature suggest a different conception of what physics is all about. Were not building a machine that calculates answers, he says, instead, were discovering questions. Natures shape-shifting laws seem to be the answer to an unknown mathematical question.

Life Beyond Our Universe? The Eerie Implications of Infinite Space

The ascension to the tenth level of intellectual heaven, says Nima Arkani-Hamed, describing the ultimate goal of physics, would be if we find the question to which the universe is the answer, and the nature of that question in and of itself explains why it was possible to describe it in so many different ways.

It now appears that the answers surround us. Its the question we dont know.

The Daily Galaxy, with Avi Shporer, Research Scientist, MIT Kavli Institute for Astrophysics and Space Research, via Institute for Advanced Studies, The New Yorker and Quanta. Avi was formerly a NASA Sagan Fellow at the Jet Propulsion Laboratory (JPL)

Image credit: ESA the early Universe

The Galaxy Report newsletter brings you twice-weekly news of space and science that has the capacity to provide clues to the mystery of our existence and add a much needed cosmic perspective in our current Anthropocene Epoch.

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The Great Question Is Our Universe Extremely Unnatural, a Weird Permutation? (Weekend Feature) - The Daily Galaxy --Great Discoveries Channel

Brian Greene is one of the foremost scientists and science communicators of our time.

Greene, a theoretical physicist at Columbia University, has been working for decades to advance our understanding of the universe and how it works. That work includes significant discoveries in the field of string theory, one of the most promising "theory of everything" candidates put forward to explain all known phenomena in the cosmos.

He also makes it a priority to spread the word of such discoveries to the masses. Greene co-founded and chairs the World Science Festival, for example, and has written a number of best-selling, critically acclaimed popular-science books. These include "The Elegant Universe" (W.W. Norton, 1999), "The Fabric of the Cosmos" (Knopf, 2004), "The Hidden Reality" (Knopf, 2011) and "Icarus at the Edge of Time" (Knopf, 2008), an illustrated children's book that features imagery captured by NASA's famous Hubble Space Telescope.

Related: The best Hubble photos of all time

And last month, Greene taught a free online course via Varsity Tutors. The interactive lecture, which he geared toward kids from fourth to eighth grade, was called "Adventures in Astrophysics: Black Holes." (If you missed it, you can watch a replay on YouTube.) He plans to do another Varsity Tutors course soon, this time about cosmology and the Big Bang.

Space.com caught up with Greene to discuss the importance of science education, why black holes are so important and interesting, and whether a theory-of-everything breakthrough could be on the horizon. The following conversation has been edited for length.

Space.com: Why did you think it was important to do a Varsity Tutors course, and why that particular topic? Why did you choose black holes?

Brian Greene: I generally think that, if we can reach the younger generation and get them excited about scientific ideas it sounds hackneyed, but I think we have a shot of bettering the world, of changing the world. Instilling that sense into the next generation is utterly vital.

And so many kids in the science classroom, their view of science is, it's all about memorizing this fact or coming up with a solution to this or that problem. And yes, that's important, but it's the big ideas that really matter. And black holes are among the most enigmatic and exciting areas of forefront science, and you don't need to know a lot to understand the basic ideas. So I geared the discussion to between fourth and eighth graders, and from the comments that I saw when they summarized what they'd learned in various postings, it felt like a lot of them got it, which is exciting.

Space.com: It feels like we're really coming into a golden age of black-hole astronomy. We've got the Event Horizon Telescope, which recently gave us our first direct image of a black hole, and we're seeing a lot of black-hole mergers, thanks to the LIGO project. Do you feel like we're finally getting a better handle on these objects? And if so, what could that tell us about the universe?

Greene: Yeah, hugely so. There was a time, 10 years ago, when you could still make an argument that maybe black holes aren't real; they're just a figment of the mathematics. But with LIGO, with the collision of two black holes giving that first ripple in the fabric of space, and with EHT even the Nobel Prize this year was awarded to work on black-hole physics. So black holes have really come into their own.

For someone like me who works on cutting-edge theoretical ideas we're struggling now to merge black holes and quantum mechanics, to get a full understanding. And black holes are the prime theoretical laboratory for pushing our ideas to the limit. When we can fully understand black holes and quantum mechanics, I suspect, our understanding of the universe is going to jump to a new level.

Related: Historic first images of a black hole show Einstein was right (again)

Space.com: And are you optimistic that that's going to happen relatively soon? Do you think there are breakthroughs on the horizon?

Greene: Yeah. There are many of us, those people who work on string theory and quantum gravity focusing upon black holes is really the predominant occupation at the moment.

And there's so much exciting work that's happening that I would suspect that, even a year or two from now, our understanding today will look relatively primitive to the new ideas that will be developed.

Space.com: Along those lines: There's some news that just came out the g-2 experiment. Do you have any thoughts about g-2 and about what that might mean for our understanding of physics? [Editor's note: The g-2 research team spotted excessive wobbling by subatomic particles called muons, suggesting that some exotic type of matter or energy may be pushing on them.]

Greene: I'm happy to answer. I would preface it by saying that results at this level of confidence the so-called three sigma, four sigma they do come and go. So one has to take it all with a grain of salt until we reach, say, the five sigma that confidence level where the chance of being a statistical fluke is like one in a million or one in a few million, as opposed to one in a thousand, which is where we are at the moment.

But, putting that to the side: If the result stands the test of time, it would suggest that the Standard Model of particle physics, which has been the gold standard of understanding, may need to be revisited. Perhaps there's a fifth force in addition to the known four forces of nature. That would be enormously exciting. Perhaps there are other particles that we've yet to discover that are shifting the value of the muon magnetic moment.

Again, I do want to stress one thing: A [different] paper came out in Nature just two days ago

Space.com: Yeah, and that one didn't see the shift [that the g-2 experiment did].

Greene: That's right. And that's using theoretical methods, but being very careful, and computer calculations. And they claim that the value that's being seen matches precisely what you'd expect from the vanilla Standard Model of particle physics, without any changes. So it's very much a fluid situation. Let's just wait and see how it all falls out.

Space.com: It strikes me that these sorts of findings show the importance of doing things like the online course that you just taught. People often kind of throw up their hands after they read a study that says "We've made a big breakthrough," and then they see another study that says, "Actually, no." A lot of people don't know how science works, that it's a process that builds upon things step by step and everything is always in flux. So, is that something that you try to get across to these kids when you're teaching them about science?

Greene: It is. Because, if you view science as just a body of facts that are static, then you're missing the drama of the discovery, where people put forward ideas, others react to the ideas, people test and observe and come back. It's a wonderful, dynamic process of human discovery. And when you see science in that light, it brings it to life in a way that a textbook of facts can never.

Space.com: Yeah. And I find, talking to people, and to kids especially they often don't even view scientists as real people. They're seen as caricatures, the wild-haired guys in the movies. I think it's really important to emphasize to kids that scientists are just people like them or like their mom or dad, and that's something that most people don't internalize really.

Greene: Yeah, it's an important lesson. And there have been attempts television shows, you know, "The Big Bang Theory" perhaps being the most prominent of them. But again, in "The Big Bang Theory," the scientists were somewhat caricatures, right? So, it was good that it was mainstream, but still there's a tendency, as you say, to see scientists as this weird collection.

In any large group, there are weird folks. But the vast majority of people are just like everybody else and just focus their attention on a certain class of questions.

Related: The biggest unsolved mysteries in physics

Space.com: Yeah. So, to go back to the very big questions: Scientists are trying to come up with a theory of everything, to find one that stands the test of time. Do you still feel like that's going to be string theory? Has what we've learned over the past five or 10 years changed any of your thinking on the biggest questions?

Greene: Well, just to be clear: Although I'm known for working on string theory and bringing string theory to general populations, I have never, ever said I believe in string theory. I have always said I have confidence that this is an interesting idea worthy of our attention that may ultimately be the final theory, but we just don't know yet.

So my assessment is pretty stable; it's pretty much the same. In the last few years, there have been great theoretical breakthroughs in string theory. There's been less contact with experiment than I would have hoped. I'd hoped that the Large Hadron Collider would reveal some of the hints of string theory. That has not happened. But that may well mean that the theory needs a bigger, better, more powerful machine to probe it, and that is not unexpected.

So I'd say that developments are happening at a fast and furious pace on the theoretical side in the hope that we'll have some connection to experiment or observation in the not-too-distant future. But that's difficult to predict.

Space.com: Are there any experiments or projects in particular whose results you're most looking forward to seeing in this regard? What could help us make progress?

Greene: Right now, it's likely that if we do get any insight from observations into string theory, it could come from, say, verifying gravitational wave observatories that might be able to probe the outskirts of a black hole with unprecedented precision. It's conceivable that in these kinds of experiments we might get a hint.

But if you're asking me in my heart of hearts, I think it's probably going to be the case that in our lifetime we're not going to get that observation or experimental insight. It may be the next generation or the generation beyond that.

Space.com: That's kind of depressing from an individual perspective, because we all want to know; we all want to get the answers. But science is a process, and we've only been at this trying to marry all the forces of nature and everything into one cohesive whole for about a century, right?

Greene: Even less at some level. There was work a century ago, but I'd say [the last] 50 years is when the real work has happened. And we're trying to push our understanding so far beyond the reach of today's experiments that it's not surprising that it may take a few generations to get there.

We're trying to answer some of the deepest questions that have ever been asked. How did the universe begin? How do the fundamental forces integrate with one another? What are the fundamental ingredients? These are questions that, in one way or another, we've been asking for a thousand, or a couple thousand, years. And if it takes another handful of decades before we get real insight, that's just how it is.

Space.com: But do you have confidence that our brains are actually capable of plumbing these depths? We're basically apes that evolved to survive on the savanna on a timescale of 70ish years. Are we capable of actually getting to the bottom of these mysteries that may be much, much deeper than we can possibly comprehend?

Greene: I'm fundamentally an optimistic person, so I've always imagined that the answer to that question is yes. But you look around this planet, and there are intelligent creatures like dogs and cats, who I suspect don't understand Einstein's general theory of relativity. Maybe I'm wrong; maybe the dogs and cats are all laughing at us right now. Maybe they've got the final answer.

But putting that to the side: Yeah, it could be that our brains are simply too limited to access the final answer, even though it's staring us in the face right now. But you go forward, you push as hard as you can. We haven't hit any insurmountable obstacles yet, and so we maintain our optimism and try to find the final answer.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.

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Black holes, string theory and more: Q&A with physicist Brian Greene - Space.com

When light gets deflected by a disordered structure it becomes difficult to estimate where the target is located. Credit: TU Wien

How do you measure objects that you cant see under normal circumstances? Utrecht University and TU Wien (Vienna) open up new possibilities with special light waves.

Laser beams can be used to precisely measure an objects position or velocity. Normally, however, a clear, unobstructed view of this object is required and this prerequisite is not always satisfied. In biomedicine, for example, structures are examined, which are embedded in an irregular, complicated environment. There, the laser beam is deflected, scattered, and refracted, often making it impossible to obtain useful data from the measurement.

However, Utrecht University (Netherlands) and TU Wien (Vienna, Austria) have now been able to show that meaningful results can be obtained even in such complicated environments. Indeed, there is a way to specifically modify the laser beam so that it delivers exactly the desired information in the complex, disordered environment and not just approximately, but in a physically optimal way: Nature does not allow for more precision with coherent laser light. The new technology can be used in very different fields of application, even with different types of waves, and has now been presented in the scientific journal Nature Physics.

You always want to achieve the best possible measurement accuracy thats a central element of all natural sciences, says Stefan Rotter from TU Wien. Lets think, for example, of the huge LIGO facility, which is being used to detect gravitational waves: There, you send laser beams onto a mirror, and changes in the distance between the laser and the mirror are measured with extreme precision. This only works so well because the laser beam is sent through an ultra-high vacuum. Any disturbance, no matter how small, is to be avoided.

But what can you do when you are dealing with disturbances that cannot be removed? Lets imagine a panel of glass that is not perfectly transparent, but rough and unpolished like a bathroom window, says Allard Mosk from Utrecht University. Light can pass through, but not in a straight line. The light waves are altered and scattered, so we cant accurately see an object on the other side of the window with the naked eye. The situation is quite similar when you want to examine tiny objects inside biological tissue: the disordered environment disturbs the light beam. The simple, regular straight laser beam then becomes a complicated wave pattern that is deflected in all directions.

However, if you know exactly what the disturbing environment is doing to the light beam, you can reverse the situation: Then it is possible to create a complicated wave pattern instead of the simple, straight laser beam, which gets transformed into exactly the desired shape due to the disturbances and hits right where it can deliver the best result. To achieve this, you dont even need to know exactly what the disturbances are, Dorian Bouchet, the first author of the study explains. Its enough to first send a set of trial waves through the system to study how they are changed by the system.

The scientists involved in this work jointly developed a mathematical procedure that can then be used to calculate the optimal wave from this test data: You can show that for various measurements there are certain waves that deliver a maximum of information as, e.g., on the spatial coordinates at which a certain object is located.

Take for example an object that is hidden behind a turbid pane of glass: there is an optimal light wave that can be used to obtain the maximum amount of information about whether the object has moved a little to the right or a little to the left. This wave looks complicated and disordered, but is then modified by the turbid pane in such a way that it arrives at the object in exactly the desired way and returns the greatest possible amount of information to the experimental measuring apparatus.

The fact that the method actually works was confirmed experimentally at Utrecht University: Laser beams were directed through a disordered medium in the form of a turbid plate. The scattering behavior of the medium was thereby characterized, then the optimal waves were calculated in order to analyze an object beyond the plate and this succeeded, with a precision in the nanometer range.

Then the team carried out further measurements to test the limits of their novel method: The number of photons in the laser beam was significantly reduced to see whether one then still gets a meaningful result. In this way, they were able to show that the method not only works, but is even optimal in a physical sense: We see that the precision of our method is only limited by the so-called quantum noise, explains Allard Mosk. This noise results from the fact that light consists of photons nothing can be done about that. But within the limits of what quantum physics allows us to do for a coherent laser beam, we can actually calculate the optimal waves to measure different things. Not only the position, but also the movement or the direction of rotation of objects.

These results were obtained in the context of a program for nanometer-scale imaging of semiconductor structures, in which universities collaborate with industry. Indeed, possible areas of application for this new technology include microbiology but also the production of computer chips, where extremely precise measurements are indispensable.

Reference: Maximum information states for coherent scattering measurements by Dorian Bouchet, Stefan Rotter and Allard P. Mosk, 21 January 2021, Nature Physics.DOI: 10.1038/s41567-020-01137-4

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Optimal Information About the Invisible: Measuring Objects That You Cant See - SciTechDaily