News Feeds

By using MRI brain scans to identify regions linked to hand movements and sensations, researchers were able to restore a sense of touch to two people with paralysis – and one was able to control and feel a robot arm using his thoughts

Droughts lasting multiple years are becoming more common and extreme around the globe, expanding by about 50,000 square kilometres annually

Pandora, a small satellite mission poised to provide in-depth study of at least 20 known planets orbiting distant stars to determine the composition of their atmospheres cleared an important milestone by completing the spacecraft bus, which acts as the spacecraft's 'brains.'

The chemical composition of a material alone sometimes reveals little about its properties. The decisive factor is often the arrangement of the molecules in the atomic lattice structure or on the surface of the material. Materials science utilizes this factor to create certain properties by applying individual atoms and molecules to surfaces with the aid of high-performance microscopes. Using artificial intelligence, a new research group now wants to take the construction of nanostructures to a new level.

The chemical composition of a material alone sometimes reveals little about its properties. The decisive factor is often the arrangement of the molecules in the atomic lattice structure or on the surface of the material. Materials science utilizes this factor to create certain properties by applying individual atoms and molecules to surfaces with the aid of high-performance microscopes. Using artificial intelligence, a new research group now wants to take the construction of nanostructures to a new level.

The robotics industry should be creating robots that could be reprogrammed and repurposed for other tasks once its life span is completed, researchers have advised.

The robotics industry should be creating robots that could be reprogrammed and repurposed for other tasks once its life span is completed, researchers have advised.

Scientists have used deep learning to design new proteins that bind to complexes involving other small molecules like hormones or drugs, opening up a world of possibilities in the computational design of molecular interactions for biomedicine.

Researchers applied the mathematical theory of synchronization to clarify how recurrent neural networks (RNNs) generate predictions, revealing a certain map, based on the generalized synchronization, that yields correct target values. They showed that conventional reservoir computing (RC), a type of RNN, can be viewed as a linear approximation, and introduced a 'generalized readout' incorporating further order approximations. Using a chaotic time-series forecasting task, they demonstrated that this approach dramatically enhances both prediction accuracy and robustness.

Paper-thin optical lenses simple enough to mass produce like microchips could enable a new generation of compact optical devices. Researchers have fabricated and tested flat lenses called Fresnel zone plates (FZPs), but did so for the first time using only common semiconductor manufacturing equipment, the i-line stepper, for the first time. These flat lenses currently lack the efficiency of in-production lenses, but have the potential to reshape optics for industries ranging from astronomy to health care and consumer electronics.

Paper-thin optical lenses simple enough to mass produce like microchips could enable a new generation of compact optical devices. Researchers have fabricated and tested flat lenses called Fresnel zone plates (FZPs), but did so for the first time using only common semiconductor manufacturing equipment, the i-line stepper, for the first time. These flat lenses currently lack the efficiency of in-production lenses, but have the potential to reshape optics for industries ranging from astronomy to health care and consumer electronics.

Data collected by wearable technology can identify disease flare-ups up to seven weeks in advance.

Data collected by wearable technology can identify disease flare-ups up to seven weeks in advance.

In 2018, a galaxy about 270 million light-years away from Earth exhibited a major increase in activity. It quieted down again by 2020 -- only to dramatically increase its output again in 2023. At that time, it began emitting radio waves at 60 times the previous intensity over just a few months, behavior which has never been monitored in real time for a supermassive black hole. Imaging also clearly shows a pair of oppositely directed plasma jets forming near the black hole and expanding outward over the course of 2023 -- 2024. The observation of jet formation in real time is another first. The data will help scientists understand how and under what conditions black holes produce jets.

Researchers have developed a novel 6D pose dataset designed to improve robotic grasping accuracy and adaptability in industrial settings. The dataset, which integrates RGB and depth images, demonstrates significant potential to enhance the precision of robots performing pick-and-place tasks in dynamic environments.

Researchers have developed a novel 6D pose dataset designed to improve robotic grasping accuracy and adaptability in industrial settings. The dataset, which integrates RGB and depth images, demonstrates significant potential to enhance the precision of robots performing pick-and-place tasks in dynamic environments.

A research team has discovered another piece in the puzzle of the formation of the Moon and water on Earth. The prevailing theory was that the Moon was the result of a collision between the early Earth and the protoplanet Theia. New measurements indicate that the Moon formed from material ejected from the Earth's mantle with little contribution from Theia. In addition, the findings support the idea that water could have reached the Earth early in its development and may not have been added by late impacts.

Triple star systems are more common than might be imagined – about one in ten of every Sun-like star is part of a system with two other stars. However, the dynamics of such a system are complex, and understanding the history of how they came to be even more so. Science took a step towards doing so with a recent paper by Emily Leiner from the Illinois Institute of Technology and her team.

They examined a star called WOCS 14020 in the star cluster M67, which is about 2,800 light years away from Earth. It is currently orbiting a massive white dwarf star with a mass of about .76 times that of the Sun (about 50% heavier than a typical white dwarf). That pairing hints at a much more interesting past.

Dr. Leiner and her team believe that WOCS 14020 was originally part of a triple star system—specifically, that it orbited a binary pair of much larger stars. Around 500 million years ago, the two stars in the binary merged, briefly creating a much more massive star that pushed some of its material onto its third companion star.

Fraser talks about stellar collisions, which caused WOCS 14020’s current state.

Absorbing that material caused WOCS 14020 to start speeding up its spin. It now rotates once every four days, rather than typically once every thirty days, which is common to other Sun-like stars. This faster rotation feature is key to Dr. Leiner and her team’s classification of the star – a “blue lurker.”

To understand what that classification means, we must first understand another type of star, the blue straggler. Blue stragglers are stars that also have gained mass from another star and appear hotter, brighter, and “bluer” than they would be expected to be given their age. In this case, all three features are directly tied together, as a hotter star is more likely to be brighter and would give off more light in the blue part of the visible spectrum, though it would still appear almost exactly like the Sun to the naked eye.

Blue lurkers are a sub-set of blue stragglers – they also gained mass from a star, but they spin faster instead of being hotter and brighter. This makes this difficult to distinguish in a cluster like M67, as they blend in better with the other surrounding stars, hence the name “lurker.” However, they are relatively rare – out of the 400 main sequence stars in M67, only around 11 are estimated to be “blue lurkers.” That puts the total, even in a space as congested as M67, at only around 3% of stars. Blue lurkers likely make up less than 1% of the general population.

A video explaining blue straggler stars.
Credit – Cosmos:elementary YouTube Channel

Since their evolutionary histories are likely to advance our understanding of the dynamics of the systems that created them, astronomers will spend more time analyzing these blue lurkers when they find them. Unique cases like WOCS 14020, where astronomers have a pretty good idea of the system’s evolutionary history, are instrumental in that regard, and the paper, which was presented at the ongoing 245th American Astronomical Society meeting, was a step towards that greater understanding.

Learn More:
STScI – NASA’s Hubble Tracks Down a ‘Blue Lurker’ Among Stars
Leiner et al – The Blue Lurker WOCS 14020 : A Long-Period Post-Common-Envelope Binary in M67 Originating from a Mergerina Triple System
UT – Blue Straggler Stars are Weird
UT – A Rare Opportunity to Watch a Blue Straggler Forming

The post Colliding Stars, Stellar Siphoning, and a now a “Blue Lurker.” This Star System has Seen it All appeared first on Universe Today.

Late this morning I fly from Burbank to Chicago (there’s a nonstop flight!) and will be home this evening. Yesterday was no-diet day, including a visit to Blinkie’s donuts, a homemade cake for me, lunch at In-N-Out Burger, and dinner at a nice Asian restaurant.

There was a disaster in my hotel room, with water suddenly spouting up from the bathroom sink drain and flooding the room (the cause is unknown). I had to flee to a new room before everything got soaked, and in the rush threw my back out! Oy! I had to sleep on the wrong (left side) to ameliorate the pain.

But I kvetch.  Today I’ll ask readers to discuss the Issues of the Day, foremost among them being the on-again off-again ceasefire deal to end the Gaza War. It looked all wrapped up, but now the Israeli cabinet has held up finalization, saying that Hamas added extra demands.  My main concern about this deal is that it appears to leave Hamas in power, which would be a disaster for Israel.

But I have to pack, so please discuss any issues you want today, and I should be back in action by Friday, or Caturday at the latest.

Bonus photo taken by Carole Hooven: Luana Maroja (right), Julia Schaletzky, and I during our discussion at the USC conference.

Happy New Year! 2025 is the centenary of some very important events in the development of quantum physics — the birth of new insights, of new mathematics, and of great misconceptions. For this reason, I’ve decided that this year I’ll devote more of this blog to quantum fundamentals, and take on some of the tricky issues that I carefully avoided in my recent book.

My focus will be on very basic questions, such as: How does quantum physics work, to the extent we humans understand it? Which of the widely-held and widely-promulgated ideas about quantum weirdness are true? And for those that aren’t, what is the right way to think about them?

I’ll frame some of this discussion in the context of the quantum two-slit experiment, because

• it’s famous,
• it’s often poorly explained
• it’s often poorly understood,
• it highlights (when properly understood) an extraordinarily strange aspect of quantum physics.

Not that I’ll cover this subject all in one post… far from it! It’s going to take quite some time.

The Visualization Problem

We humans often prefer to understand things visually. The problem with explaining quantum physics, aside from the fact that no one understands it 100%, is that all but the ultra-simplest problems are impossible to depict in an image or animation. This forces us to use words instead. Unfortunately, words are inherently misleading. Even when partial visual depictions are possible, they too are almost always misleading. (Math is helpful, but not as much as you’d think; it’s usually subtle and complicated, too.) So communication and clear thinking are big challenges throughout quantum physics.

These difficulties lead to many widespread misconceptions (some of which I myself suffered from when I was a student first learning the subject.) For instance, one of the most prevalent and problematic, common among undergraduates taking courses in chemistry or atomic physics, is the wrong idea that each elementary particle has its own wavefunction — a function which tells us the probability of where it might currently be located. This confusion arises, as much as anything else, from a visualization challenge.

Consider the quantum physics of the three electrons in a lithium atom. If you’ve read anything about quantum physics, you may have been led to believe that that each of the three electrons has a wave function, describing its behavior in three-dimensional space. In other words,

• naively the system would be described by three wave functions, each in three dimensions; each electron’s wave function tells us the probability that it is located at this point or that one;
• but in fact the three electrons are described by one wave function in nine dimensions, telling us simultaneously the overall probability that the first electron is t be found at this point, the second at that point, and the third at some other point.

Unfortunately, drawing something that exists in nine dimensions is impossible! Three wave functions in three dimensions is much easier to draw, and so, as a compromise/approximation that has some merits but is very foncusing, that method of depiction is widely used in images of multiple electrons. Here, for instance, two of the lithium atom’s electrons are depicted as though they have wave functions sharing the yellow region (the “inner shell”), while the third is drawn as though it has a wave function occuping the [somewhat overlapping] blue region (the “next shell”). [The atomic nucleus is shown in red, but far larger than it actually is.] Something similar is done in this image of the electrons in oxygen from a chemistry class.)

Yet the meat of the quantum lithium atom lies in the fact that there’s actually only one wave function for the entire system, not three. Most notably, the Pauli exclusion principle, which is responsible for keeping the electrons from all doing the same things and leads to the shell-like structure, makes sense only because there’s only one wave function for the system. And so, the usual visual depictions of the three electrons in the atom are all inherently misleading.

Yet there’s no visual image that can replace them that is both correct and practical. And that’s a real problem.

That said, it is possible to use visual images for two objects traveling in one dimension, as I did in a recent article that explains what it means for a system of two particles to have only one wave function. But for today, we can set this particular issue aside.

What We Can’t Draw Can Hurt Our Brains

Like most interesting experiments, the underyling quantum physics of the quantum double slit experiment cannot be properly drawn. But depicting it somehow, or at least parts of it, will be crucial in understanding how it works. Most existing images that are made to try to explain it leave out important conceptual points. The challenge for me — not yet solved — is to find a better one.

In this post, I’ll start the process, opening a conversation with readers about what people do and don’t understand about this experiment, about what’s often said about it that is misleading or even wrong, and about why it’s so hard to draw anything that properly represents it. Over the year I expect to come back to the subject occasionally. With luck, I’ll find a way to describe this experiment to my satisfaction, and maybe yours, before the end of the year. I don’t know if I’ll succeed. Even if I do, the end product won’t be short, sweet and simple.

But let’s start at the beginning, with the conventional story of the quantum double-slit experiment. The goal here is not so much to explain the experiment — there are many descriptions of it on the internet — but rather to focus on exactly what we say and think about it. So I encourage you to read slowly and pay very close attention; in this business, every word can matter.

Observing the Two Slits and the Screen

We begin by throwing an ultra-microscopic object — perhaps a photon, or an electron, or a neutrino — toward a wall with two narrow, closely spaced slits cut in it. (The details of how we do this are not very important, although we do need to choose the slits and the distance to the screen with some care.) If the object manages to pass through the wall, then on the other side it continues onward until it hits a phosphorescent screen. Where it strikes the screen, the screen lights up. This is illustrated in Fig. 1, where several such objects are showing being sent outward from the left; a few pass through the slits and cause the screen to light up where they arrive.

Figure 1: Microscopic objects are emitted from a device at left and travel (orange arrows) toward a wall (grey) with two narrow slits in it. Each object that passes through the slits reaches a screen (black) where it causes the screen to light up with an orange flash.

If we do this many times and watch the screen, we’ll see flashes randomly around the screen, something like what is shown in Fig. 2:

Figure 2: (click to animate if necessary): The screen flickers with little dots, one for each object that impacts it.

But now let’s keep a record of where the flashes on the screen appear; that’s shown in Fig. 3, where new flashes are shown in orange and past flashes are shown in blue. When we do this, we’ll see a strange pattern emerge, seen not in each individual flash but over many flashes, growing clearer as the number of flashes increases. This pattern is not simply a copy of the shape of the two slits.

Figure 3 (click to animate if necessary): Same as Fig. 2, except that we record the locations of past flashes, revealing a surprising pattern.

After a couple of thousand flashes, we’ll recognize that the pattern is characteristic of something known as interference (discussed further in Figs. 6-7 below):

Figure 4: The interference pattern that emerges after thousands of objects have passed through the slits.

By the way, there’s nothing hypothetical about this. Performing this experiment is not easy, because both the source of the objects and the screen are delicate and expensive. But I’ve seen it done, and I can confirm that what I’ve told you is exactly what one observes.

Trying to Interpret the Observations

The question is: given what is observed, what is actually happening as these microscopic objects proceed from source through slits to screen? and what can we infer about their basic properties?

We can conclude right away that the objects are not like bullets — not like “particles” in the traditional sense of a localized object that travels upon a definite path. If we fired bullets or threw tiny balls at the slitted wall, the bullets or balls would pass through the two slits and leave two slit-shaped images on the screen behind them, as in Fig. 5.

Figure 5: If balls, bullets or other particle-like objects are thrown at the wall, those that pass through the slits will arrive at the screen in two slit-shaped regions.

Nor are these objects ripples, meaning “waves” of some sort. Caution! Here I mean what scientists and recording engineers mean by “wave”: not a single wave crest such as you’d surf at a beach, but rather something that is typically a series of wave crests and troughs. (Sometimes we call this a “wave set” in ordinary English.)

If each object were like a wave, we’d see no dot-like flashes. Instead each object would leave the interference pattern seen in Fig. 4. This is illustrated in Fig. 6 and explained in Fig. 7. A wave (consisting of multiple crests and troughs) approaches the slits from the left in Fig. 6. After it passes through the slits, a striking pattern appears on the screen, with roughly equally spaced bright and dark regions, the brightest one in the center.

Figure 6: If a rippling pattern — perhaps one of sound waves or of water waves — is sent toward the wall, what appears on the screen will be an interference pattern similar to that of Fig. 4. See Fig. 7 for the explanation. The bright zones on the screen may flicker, but the dark zones will always be dark.

Where does the interference pattern come from? This is clearest if we look at the system from above, as in Fig. 7. The wave is coming in from the left, as a linear set of ripples, with crests in blue-green and troughs in red. The wall (represented in yellow) has two slits, from which emerge two sets of circular ripples. These ripples add and subtract from one another, making a complex, beautiful “interference” pattern. When this pattern reaches the screen at the opposite wall, it creates a pattern on the screen similar to that sketched in Fig. 6, with some areas that actively flicker separated by areas that are always dark.

Fig. 7: The interference pattern created by a linear wave pattern passing through two slits, as depicted from above. The two slits convert the linear ripples to two sets of circular ripples, which cross paths and interfere. When the resulting pattern arrives at the screen at right, some areas flicker, while others between them always remain quiet. A similar pattern of activity and darkness, though with some different details (notably fewer dark and bright areas), is seen in Figs. 3, 4 and 6. Credit: Lookang, with many thanks to Fu-Kwun Hwang and author of Easy Java Simulation = Francisco Esquembre, CC BY-SA 3.0 Creative Commons license via Wikimedia Commons

It’s important to notice that the center of the phosphorescent screen is dark in Fig. 5 and bright in Fig. 6. The difference between particle-like bullets and wave-like ripples is stark.

And yet, whatever objects we’re dealing with in Figs. 2-4, they are clearly neither like the balls of Fig. 5 nor the waves of Fig. 6. Their arrival is marked with individual flashes, and the interference pattern builds up flash by flash; one object alone does not reveal the pattern. Strangely, each object seems to “know” about the pattern. After all, each one, independently, manages to avoid the dark zones and to aim for one of the bright zones.

How can these objects do this? What are they?

What Are These Objects?!

According to the conventional wisdom, Fig. 2 proves that the objects are somewhat like particles. When each object hits the wall, it instantaneously causes a single, tiny, localized flash on the screen, showing that it is itself a single, tiny, point-like object. It’s like a bullet leaving a bullet-hole: localized, sudden, and individual.

According to the conventional wisdom, Figs. 3-4 prove that the objects are somewhat like waves. They leave the same pattern that we would see if ocean swell were passing through two gaps in a harbor’s breakwater, as in Fig. 7. Interference patterns are characteristic only of waves. And because the interference pattern builds up over many independent flashes, occurring at different times, each object seems to “know,” independent of the others, what the interference pattern is. The logical conclusion is that each object interferes with itself, just as the waves of Figs. 6-7 do; otherwise how could each object “know” anything about the pattern? Interfering with oneself is something a wave can do, but a bullet or ball or anything else particle-like certainly cannot.

To review:

• A set of particles going through two slits wouldn’t leave an interference pattern; it would leave the pattern we’d expect of a set of bullets, as in Fig. 5.
• But waves going through two slits wouldn’t leave individual flashes on a screen; each wave would interfere with itself and leave activity all over the screen, with stronger and weaker effects in a predictable interference pattern, as in Figs. 6-7.

It’s as though the object is a wave when it goes through and past the slits, and turns into a particle before it hits the screen. (Note my careful use of the words “as though”; I did not say that’s what actually happens.)

And thus, according to the conventional wisdom, each object going through the slits is… well… depending on who you talk to or read…

• both a wave and a particle, or
• sometimes a wave and sometimes a particle, or
• equally wave and particle, or
• a thing with wave-like properties and with particle-like properties, or
• a particle-like thing described by a probability-wave (also known as a “wave function”), or
• a wave-like thing that can only be absorbed like a particle, or…
• ???

So… which is it?

Or is it any of the above?

Looking More Closely

We could try to explore this further. For instance, we could try to look more closely at what is going on, by asking whether our object is a particle that goes through one slit or is a wave that goes through both.

Figure 8: We might try to investigate further, by adding sensors just behind the slits, to see whether each object goes through one slit (as for a bullet) or goes through both (as for a sound wave). With certain sensors, we will find it goes through only one — but in this case, what appears on the screen will also change! We will see not what is in Fig. 4 but rather what appears in Fig. 9.

But the very process of looking at the object to see what slit it went through changes the interference pattern of Figs. 4 and 6 into the pattern in Fig. 5, shown in Fig. 9, that we’d expect for particles. We find two blobs, one for each slit, and no noticeable interference. It’s as though, by looking at an ocean wave, we turned it into a bullet, whereas when we don’t look at the ocean wave, it remains an ocean wave as it goes through the gaps, and only somehow coalesces into a bullet before it hits (or as it hits) the screen.

Figure 9: If sensors are added to try to see which slit each object passes through (or both), the pattern seen on the screen changes to look more like that of Fig. 5, and no clarity as to the nature of the objects or the process they are undergoing is obtained.

Said another way: it seems we cannot passively look at the objects. Looking at them is an active process, and it changes how they behave.

So this really doesn’t clarify anything. If anything, it muddies the waters further.

What sense can we make of this?

Before we even begin to try to make a coherent understanding out of this diverse set of observations, we’d better double-check that the logic of the conventional wisdom is accurate in the first place. To do that, each of us should read very carefully and think very hard about what has been observed and what has been written about it. For instance, in the list of possible interpretations given above, do the words “particle” and “wave” always mean what we think they do? They have multiple meanings even in English, so are we all thinking and meaning the same thing when we describe something as, say, “sometimes a wave and sometimes a particle”?

If we are very careful about what is observed and what is inferred from what is observed, as well as the details of language used to communicate that information, we may well worry about secret and perhaps unjustified assumptions lurking in the conventional wisdom.

For instance, does the object’s behavior at the screen, as in Fig. 2, really resemble a bullet hitting a wall? Is its interaction with the screen really instantaneous and tiny? Are its effects really localized and sudden?

Exactly how localized and sudden are they?

All we saw at the screen is a flash that is fast by human standards, and localized by human standards. But why would we apply human standards to something that might be smaller than an atom? Should we instead be judging speed and size using atomic standards? Perhaps even the standards of tiny atomic nuclei?

If our objects are among those things usually called “elementary particles” — such as photons, electrons, or neutrinos — then the very naming of these objects as “elementary particles” seems to imply that they are smaller than an atom, and even than an atom’s nucleus. But do the observations shown in Fig. 2 actually give some evidence that this is true? And if not… well, what do they show?

What do we precisely mean by “particle”? By “elementary particle”? By “subatomic particle”?

What actually happened at the slits? at the screen? between them? Can we even say, or know?

These are among the serious questions that face us. Something strange is going on, that’s for sure. But if we can’t first get our language, our logic, and our thinking straight — and as a writer, if I don’t choose and place every single word with great care — we haven’t a hope of collectively making sense of quantum physics. And that’s why this on-and-off discussion will take us all of 2025, at a minimum. Maybe it will take the rest of the decade. This is a challenge for the human mind, both for novices and for experts.