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A new study sheds light on how the extreme miniaturization of thin films affects the behavior of relaxor ferroelectrics -- materials with noteworthy energy-conversion properties used in sensors, actuators and nanoelectronics.

The future of manufacturing is not just about machines and AI; it's about re-empowering humans, according to a new study.

The future of manufacturing is not just about machines and AI; it's about re-empowering humans, according to a new study.

Qubits -- the fundamental units of quantum information -- drive entire tech sectors. Among them, superconducting qubits could be instrumental in building a large-scale quantum computer, but they rely on electrical signals and are difficult to scale. In a breakthrough, a team of physicists has achieved a fully optical readout of superconducting qubits, pushing the technology beyond its current limitations.

Qubits -- the fundamental units of quantum information -- drive entire tech sectors. Among them, superconducting qubits could be instrumental in building a large-scale quantum computer, but they rely on electrical signals and are difficult to scale. In a breakthrough, a team of physicists has achieved a fully optical readout of superconducting qubits, pushing the technology beyond its current limitations.

Triple click chemistry has revolutionized chemical synthesis with its simplicity and efficiency, allowing for the quick and selective assembly of complex molecules. Now, in a recent study, researchers developed novel trivalent platforms capable of producing highly functional triazoles in straightforward one-pot reactions. These platforms have significant potential in drug development, materials science, and bioengineering, promising advancements in sustainable chemistry and biomedical innovations.

Researchers have developed an artificial intelligence (AI) tool that will help predict endangered whale habitat, guiding ships along the Atlantic coast to avoid them. The tool is designed to prevent deadly accidents and inform conservation strategies and responsible ocean development.

Rhobo6, a light microscopy probe, gives scientists an unprecedented look at the extracellular matrix -- the collection of organized molecular structures that fills the spaces between cells in our bodies.

A major challenge in self-powered wearable sensors for health care monitoring is distinguishing different signals when they occur at the same time. Researchers addressed this issue by uncovering a new property of a sensor material, enabling the team to develop a new type of flexible sensor that can accurately measure both temperature and physical strain simultaneously but separately to more precisely pinpoint various signals.

Researchers have discovered that superconducting nanowire photon detectors can also be used as highly accurate particle detectors, and they have found the optimal nanowire size for high detection efficiency.

The appearance of the Interstellar Objects (ISOs) Oumuamua and Comet Borisov in 2017 and 2019, respectively, created a surge of interest. What were they? Where did they come from? Unfortunately, they didn’t stick around and wouldn’t cooperate with our efforts to study them in detail. Regardless, they showed us something: Milky Way objects are moving around the galaxy.

We don’t know where either ISO came from, but there must be more—far more. How many other objects from our stellar neighbours could be visiting our Solar System?

The Alpha Centauri (AC) star system is our nearest stellar neighbour and consists of three stars: Alpha Centauri A and Alpha Centauri B, which are in a binary relationship, and Proxima Centauri, a dim red dwarf. The entire AC system is moving toward us, and it presents an excellent opportunity to study how material might move between Solar Systems.

New research to be published in the Planetary Science Journal examines how much material from AC could reach our Solar System and how much might already be here. It’s titled “A Case Study of Interstellar Material Delivery: Alpha Centauri.” The authors are Cole Greg and Paul Wiegert from the Department of Physics and Astronomy and the Institute for Earth and Space Exploration at the University of Western Ontario, Canada.

“Interstellar material has been discovered in our Solar System, yet its origins and details of its transport are unknown,” the authors write. “Here we present Alpha Centauri as a case study of the delivery of interstellar material to our Solar System.” AC likely hosts planets and is moving toward us at a speed of 22 km s?1, or about 79,000 km per hour. In about 28,000 years it will reach its closest point and be about 200,000 astronomical units (AU) of the Sun. According to Greg and Wiegert, material ejected from AC can and will reach us, and some is already here.

AC is considered a mature star system about five billion years old that hosts planets. Mature systems are expected to eject less material, but since AC has three stars and multiple planets, it likely ejects a considerable amount of material. “Though mature star systems likely eject less material than those in their
planet-forming years, the presence of multiple stars and planets increases the likelihood of gravitational scattering of members from any remnant planetesimal reservoirs, much as asteroids or comets are currently being ejected from our Solar System,” the authors write.

We know that macro objects like Borisov and Oumuamua have reached our Solar System, and we also know that interstellar dust has reached our system. The Cassini probe detected some, and researchers reported on it in 2003. Existing models for material ejection from star systems are partly based on what we know about our Solar System and how it ejects material, and Greg and Wiegert based their work on those models.

Artist’s impression of `Oumuamua. While large ISOs like this grab our attention, dust particles from other star systems are also interstellar objects. Credit: ESO/M. Kornmesser

The research shows that there are potentially large quantities of material from AC. The authors write that “the current number of Alpha Centauri particles larger than 100 m in diameter within our Oort Cloud to be 106,” or 1 million. However, these objects are extremely difficult to detect. Most of them are likely in the Oort Cloud, a long distance from the Sun. The pair of researchers explain that “the observable fraction of such objects remains low” and that there is only a one-in-a-million chance that one is within 10 AU of the Sun.

This animation brings some of the research results to life. “Alpha Centauri’s orbit about the Galactic Centre viewed on the xy and yz planes (top row), as well as the orbits of the ejecta from Alpha Centauri viewed in a comoving frame (bottom row). Our Sun (Sol) is marked by a black hexagon, and its orbital path is indicated by a grey solid line (top row only). Alpha Centauri’s location and path are shown by a yellow star and a solid blue line (top row only). In the bottom row, the comoving frame follows Alpha Centauri around its orbit while maintaining its orientation with the y-axis pointing towards the Galactic Centre (blue arrow) and Alpha Centauri’s velocity pointing in the -x direction (black arrow). This still frame is taken at t?3,000 yr (that is, +3,000 years from the current epoch) after ~100 Myr of integration. The colours of the ejecta represent the 3rd dimension of position, except that any particle that will at any point come within 100,000 au of Sol is plotted in red. This shows the time evolution from t? -100 Myr to t? 10 Myr,” the authors write.

The researchers ran simulations to determine how much material can reach us from AC. The simulations ran for 110 million years from t= -100 myr to t= 10 myr. During that span, AC ejected 1,090,000 particles. They were ejected in random directions at different speeds, and only a tiny amount came anywhere near the Sun. “Only a small fraction of the AC ejecta come within the CA (close approach) distance of the Sun. In total, 350 particles had a CA with the Solar System, ~0.03% of the total ejecta,” the authors explain.

This figure from the study focuses on the 360 particles that make close approaches. “The heliocentric equatorial radiant for the 350 close approaches at the time of their closest Solar approach (“Arrival Time”), with the current heliocentric equatorial coordinates of Alpha Cen plotted as a black star and the “effective radiant” corresponding to Alpha Cen’s apparent velocity is plotted as a red star. The purple-shaded region is the combined projection of the effective cross-section of the Solar System (solid angle size as seen from Alpha Cen) from the start of the simulation up to the current time.”

The research shows that there are plausible pathways for particles from AC to reach our Solar System. How large can they be?

According to the authors, small particles that would appear as meteors in Earth’s atmosphere are not likely to reach us. They’re subjected to too many forces on their way, including magnetic fields, drag from the interstellar medium, and destruction through sputtering or collisions. “Small particles travelling through the interstellar medium (ISM) are subject to a number of effects not modelled here,” they explain.

They computed the minimum size of particles that could make the journey. “We extracted the relevant parameters for each of the 350 CAs from our simulation and computed the minimum size needed for a grain travelling along that trajectory to survive all three effects,” the authors write. They found that a particle with a median of 3.30 micrometres can survive the journey.

“At this size and speed, the particle can travel 125 pc in the ISM before grain destruction becomes relevant, 4200 pc for ISM drag, and only 1.5 pc for magnetic forces, and thus our typical particles are effectively magnetically limited,” the researchers explain. “In fact, all of our particles are limited by magnetic forces.” The authors also point out that these tiny grain sizes are undetectable by meteor radar instruments like the Zephyr Meteor Radar Network.

These results are hampered by our poor understanding of our Solar System’s material ejection rate, on which the research is partly based. “Unfortunately, the rate of ejection of material from Alpha Cen is poorly constrained,” write Greg and Wiegert.

However, with that in mind, the research shows that some material can reach us and is already here. Most of it travelled for less than 10 Myr to reach us, but it has to be larger than about 10 microns to survive the journey. It also estimates that about 10 particles from Alpha Centauri become detectable meteors in Earth’s atmosphere currently, with that number increasing by a factor of ten in the next 28,000 years.

This research presents a concrete example of how our Solar System is anything but isolated. If material from star systems can move freely to and from one another, it opens up another window into the planet formation process. If AC does host exoplanets, some of the material reaching us could be from the same reservoir of material that those planets formed from. It could be possible to learn something about those planets directly without having to overcome the vast distance between us and Alpha Centauri.

“A thorough understanding of the mechanisms by which material could be transferred from Alpha Centauri to the Solar System not only deepens our knowledge of interstellar transport but also opens new pathways for exploring the interconnectedness of stellar systems and the potential for material exchange across the Galaxy,” the authors conclude.

Research: A Case Study of Interstellar Material Delivery: Alpha Centauri

The post Material from Alpha Centauri is Already Here appeared first on Universe Today.

In a groundbreaking discovery, a NASA CubeSat has detected new radiation belts around Earth following a powerful solar storm in May 2024. This discovery reshapes our understanding of how solar activity interacts with Earth’s magnetic field, creating new zones of trapped particles. CubeSat, which was designed to study space weather, has captured data that could have major benefits for satellite operations, astronaut safety, and future space missions. As solar activity intensifies in the coming years, this discovery highlights the need for continued monitoring of the interactions between the Earth and Sun.

The radiation belts around Earth, known as the Van Allen Belts, are doughnut-shaped regions of charged particles trapped by Earth’s magnetic field. The belts that were discovered in 1958 by the Explorer 1 mission consist mostly of high-energy electrons and protons originating from the Sun. The inner belt, located about 600 to 6,000 kilometres above Earth, contains highly energetic protons, while the outer belt, extending from 13,500 to 60,000 kilometres is mostly made up of electrons. These radiation zones pose risks to satellites, astronauts, and space missions, requiring shielding and careful navigation. 

The Van Allen radiation belts surrounding Earth. Image: NASA

Something largely unexpected happened back in May 2024 when a large solar storm hit Earth. In the days that followed, high energy particles from the Sun bathed the Earth sparking auroral displays and disrupting GPS communications. A NASA satellite has since discovered this storm created two new but temporary radiation belts that circle the Earth. The two belts sit between the other two existing belts and form concentric rings above the equator. 

Ohio’s Aurora 05-10-2024, captured in front of John Chumack’s observatory domes at JBSPO in Yellow Springs, Ohio. Credit: John Chumack, used by permission. Canon 6DDSLR 16mm F2.8 lens, ISO 1250, 10 second Exp.

The discovery was made by the Colorado Inner Radiation Belt Experiment Satellite (bit of a mouthful so it’s shortened to CIRBE) on 6 February this year. The announcement was made in the Journal of Geophysical Research : Space and Physics. The CubeSat had been in space for about a year before it experienced what NASA reported as an anomaly and the satellite went quiet on 15 April. The satellite was out of action during the storm in May last year but it unexpectedly leapt back to life on 15 June. It then resumed taking measurements and it was this that led to the discovery of the new belts. Understanding them is of crucial importance since satellites heading into geostationary orbits have to travel through the radiation belts. 

The CIRBE CubeSat in the laboratory before launch. CIRBE was designed and built by LASP at the University of Colorado Boulder. Xinlin Li/LASP/CU Boulder

It’s not unusual for temporary belts to be identified following large solar storms but these new belts seem to last much longer. Previously the temporary belts were sustained for around four weeks but the new belts seem to have lasted for more than three months.  They are composed mostly of electrons like the outer belt but with the new innermost belt hosting a substantial quantity of protons too. 

Quite how long the new belts will last will depend on solar storms that follow and how strong they are. Larger storms tend to have more energy and are more likely to destroy the particles in the belts, knocking them out of their orbit. A solar storm in June reduced the size of one of the new belts and another storm in August of last year almost completely destroyed it. 

Source : NASA CubeSat Finds New Radiation Belts After May 2024 Solar Storm

The post NASA CubeSat Discovers New Radiation Belts After Intense Solar Storm appeared first on Universe Today.

Here we have two notables on opposite sides of the religion-versus-faith issue, or at least clashing about how to deal with the oft-claimed incompatibility between science and religion. In one corner is Sam Harris, who, as you know, is a hard-core critic of faith, and not shy about saying that. His book The End of Faith could be counted as the beginning of New Atheism. In the other corner is Brian Greene, who doesn’t like to criticize religion because, he says, confrontation turns people off (he refused to autograph my Faith vs. Fact book that I was auctioning off for charity).  And Greene doesn’t mind taking Templeton money to fund his World Science Festival.

This 9-minute discussion, from 2018, is part of a 2+-hour discussion you can find here.

Greene argues there’s a big reason to avoid being as hard-core as Harris. He claims that being vociferous (apparently like Harris or Dawkins) undercuts the stated goal of atheists to spread rationality. For Greene sees New Atheists as elitists who tell people that they are “stupid”—a contention that we often hear but I don’t think carries much truth. (Try finding such a statement in Faith vs. Fact!) Rather, Greene believes that people’s deconversion is best accomplished indirectly: by getting people to appreciate the natural wonders of the universe and showing your passion for them. This, he thinks, “will drive things in a good direction.” (I believe he means letting go of religion, though Greene isn’t explicit.) I can’t quite see how that would work.

Sam responds that people’s minds can change; believers can become nonbelievers. That is true, and I’ve seen it and, indeed, have even been instrumental in changing some minds that way. (No, I don’t call people “stupid.”)  Greene responds that he’s changed minds, too, but yet he fails to show that the “soft” approach is more efficacious. How many I-got-people-to-give-up-religion anecdotes does he have? As Sam says, “You’re talking about the carrot and I’m talking about the stick. And the stick works.”  This exchange, by the way, is hilarious.

Sam responds that there are some religious views that in fact facilitate the ruination of nature (global warming, for example, can be justified as a necessary precursor of The End Times).  Greene responds that he’s rarely confronted with such people.

My methods are clearly the same as Sam’s, though I wouldn’t for a minute tell Greene that he has to go after religion big-time. That’s just not his way. However—and I don’t have evidence for this—I do think that the direct approach to criticizing faith, one that avoids ad hominem attacks—is more efficacious. I don’t think telling people that science and faith are perfectly compatible, for instance, can account for the rise of the “nones” in recent years. It appears that many people have become “nones” because they realized that religion is irrational and in conflict with science. As a paper published in 2023 noted:

. . . . the authors queried self-identified religious nones about their reasons for leaving their religion. In response, each participant wrote a short personal essay, which was coded by the research team. Four primary themes emerged. About half of the sample (51.8%) reported leaving for intellectual reasons or because they outgrew their faith. Roughly a fifth of the sample (21.9%) reported religious trauma, such as the hypocrisy of the sexual abuse scandals in the Catholic Church. Others (14.9%) reported leaving religion because of personal adversity, such as an inability to make sense of the tragic death of a child, or social reasons (11.4%), including a religious community’s being unwelcoming.

In other words, by far the most common reason for leaving faith is because people perceive that it has no intellectual underpinnings. They don’t leave it because appreciating a passion for the university changes them “in a good way”. (Note that New Atheists also emphasize at least two of the other three reasons people give up their faith.)

The US National Institute of Standards and Technology, which is tasked with developing standards for encryption that can protect against quantum computers, may be at risk

As you know the University of Chicago was the first higher-ed school in America to adopt a position of institutional neutrality. This was done in 1967, with the principle embodied in our Kalven Report.  Kalven prohibits the University or its units, including departments and centers, from taking official stands on political, moral, and ideological issues—save in those cases where the issue is one that could affect the mission of our University.  According to FIRE, which approves of this position of institutional neutrality, some 29 other colleges or boards of education have joined Chicago in adopting one.

Deviations from the position of neutrality are rare, but this morning we learned that our President, Paul Alivisatos, has declared official University opposition to the Trump’s administration of slashing “indirect costs” on NIH grants. “Indirect costs” are the payments the University gets on top of an award when a researcher or entity gets a grant. They are supposed to be used to support the research through university costs and infrastructure, paying, for example, for building maintenance, administrative costs, electricity, water, and other costs not directly involved in doing research.  Each university negotiates its indirect costs directly with the NIH, and they typically range between 25% to 70% of the money awarded the researcher.

So, for example, if I asked for $2 million in research for monies for a three-year NIH grant, having calculated the costs of doing the research and paying grad students and postdocs, I would ask for that amount of money. Our overhead rate is 64%, so if I got the grant, the university would receive an extra $1,280,000 in overhead, so the whole award would cost the NIH over $3 million.

Now not all the overhead is used to support the specific research grant funded, as there’s no way to exactly calculate infrastructure costs.  Universities therefore often put the overhead money into a big pot used to support the university as a whole, and often it’s not clear where that overhead money goes, nor is it clear that all of it supports research.   But it is clear that overhead is crucial for keeping universities running and that a lot of it does cover the costs doing research (animal facilities, safety assurance, OSHA compliance, and so on). The Chicago Maroon reports that the cuts will cost our University $52 million in yearly revenue.

It was a big deal, then, when the Trump administration decided to cap the indirect cost rate on NIH grants at 15%, which would result in a severe loss of money to research-oriented universities—amounting in toto to billions of dollars.  The NIH verified this in their own announcement.  To President Alivisatos, this slashing represents an impediment to the mission of the University of Chicago, and so we broke neutrality, as delineated below his announcement below. I’ve put a screenshot of the announcement, but have put the words in larger type below it:

I’ve put the parts in bold where the University has taken an official stand:

Dear Colleagues,

In recent weeks, a large number of executive orders and federal policy changes have been issued. Following an election, policy changes are an expected part of our democracy. Yet today, some of these, if implemented, would have far-ranging adverse impacts on institutions of higher education and academic medical centers, including ours. These matters stand to affect our institution substantially, and I have a duty to act in support of our core interests.

Yesterday, I authorized that we join over a dozen plaintiff universities and associations in a suit to challenge the sudden reduction in NIH indirect costs that was announced Friday evening. The precipitous timing of this move would immediately damage the ability of our faculty, students, and staff (and those of other academic institutions and medical centers across the nation) to engage in health-related fundamental research and to discover life-saving therapies. For many, indirect costs may conjure images of administrative waste, but the truth is: this is a mechanism through which federal grants support essentials like state-of-the-art lab facilities and cybersecurity to protect data privacy.

I–and the leadership from across the University–are monitoring the policy developments closely. We look at each issue carefully and with an open mind. In this rapidly evolving landscape, where appropriate, the University is acting on our community’s behalf on a wide range of issues in defense of our operations and mission.

This is a period of contestation and change, and in such a moment it is important to keep our focus on what we treasure in UChicago. Ours is an extraordinary community where we advance our mission to create new knowledge, where we offer students a deep and meaningful education, where we forge new understanding, and where our medical enterprise offers new therapies and care for patients. This is a place where we are committed to open debate, to rigor and to excellence, and where we recognize that diversity of viewpoint and experience enriches our ability to seek truths. Realizing these values is a constant and good struggle, and academic freedom and freedom of inquiry and expression are the fundamental principles that make them possible. The work of the members of this community is important. For these reasons, since the University’s founding, this community has been committed to upholding those ideals–and will remain steadfast to honoring them.

Many of you have questions; local leadership across the schools, units, and divisions will have the most up-to-date information. We are collaborating with other institutions and utilizing the tools available to us to counter actions that would adversely affect our ability to fulfill our calling.

Sincerely,
Paul

——-

Paul Alivisatos

President

Harvard had similar objections:

Every scientific and medical breakthrough, whether in basic or applied research, depends on the people who conduct the research, as well as the materials and laboratory equipment they use. These components of research, readily attributable to a specific project, are funded as direct costs, but they do not encompass all essential aspects of research. The work also requires laboratory facilities, heat and electricity, and people to administer the research and ensure that it is conducted securely and in accordance with federal regulations. The expenditures for these critical parts of the research enterprise are called indirect costs. They are substantial, and they are unavoidable, not least because it can be very expensive to build, maintain, and equip space to conduct research at the frontiers of knowledge.

Implementing a 15 percent cap on indirect support, as the NIH has announced it intends to do, would slash funding and cut research activity at Harvard and nearly every research university in our nation. The discovery of new treatments would slow, opportunities to train the next generation of scientific leaders would shrink, and our nation’s science and engineering prowess would be severely compromised. At a time of rapid strides in quantum computing, artificial intelligence, brain science, biological imaging, and regenerative biology, and when other nations are expanding their investment in science, America should not drop knowingly and willingly from her lead position on the endless frontier.

Since this just happened, I’ll leave the lawsuiting to the University, though I note that a federal judge has put these cuts on temporary hold as the attorneys general of 22 states, including Illinois, have filed a lawsuit claiming that the cut would irreparably damage research.  In the meantime, those of us in the free-speech community here are pondering whether and how the cuts really do endanger the stated mission of our university. It would seem obvious that it does, since part of our mission is to generate knowledge through research, but there are two caveats. Does the mission per se include medical research designed to save lives—that is, to create medical innovations? Is that part of our our mission statement? And does the mission of the university include protecting its operational budget, assuring a comfortable financial bottom line? If so, how much overhead do we require?

Clearly our university and others construe this as part of our mission, and I’m not going to object. But clearly we need to think harder about what the mission of a university like ours really is.

The last time the University of Chicago broke institutional neutrality was in 2017, when the U of C declared opposition to Trump’s cancellation of the DACA (“Dreamers”) act because having Dreamers here as part of the university was considered helping fulfill our mission, and deporting them would thus impede our mission.  As the Chicago Maroon noted at the time:

The University declined to support the DREAM Act in 2010, citing the 1967 Kalven Report which recommended that the University generally avoid taking political stances, and University spokesperson Jeremy Manier maintained this position in an e-mail to The Maroon Tuesday.

“The DREAM Act encompasses issues that do not directly affect the University,” he said in the e-mail. “However, in general the University strongly supports efforts to address this issue through legislation that protects the ability of DACA-eligible students to live in the United States and pursue their education and careers here.”

That breaks institutional neutrality. Such declarations are rare here, and thus today’s announcement is a big deal for the University of Chicago.

The debate over when consciousness arises has been revitalised by new tests of awareness in infants – raising the possibility that it emerges just before birth

As the search for extraterrestrial life continues, scientists have identified the hidden oceans beneath icy moons as target locations for discovery. However, new research from the University of Reading suggests these alien seas may be better at masking their secrets than previously believed. Thick ice layers and complex chemical processes could make detecting signs of life from spacecraft far more challenging. The discovery presents significant obstacles for future missions to moons like Europa and Enceladus, where subsurface oceans might host the clues needed to finally confirm life beyond Earth.

Europa, one of Jupiter’s largest moons, has a subsurface ocean beneath an icy crust. Research to date suggests that this hidden ocean, kept liquid by tidal heating from the gravity of Jupiter, could contain the necessary ingredients for life, including water, energy, and essential chemicals. Surface features such as cracks and ridges suggest that water from the ocean occasionally seeps through the ice, possibly carrying organic material to the surface. NASA’s upcoming Europa Clipper mission aims to investigate the moon’s habitability by analyzing its surface and subsurface environment. If life exists beyond Earth, Europa’s ocean may be one of the best places to find it.

Europa captured by Juno

Another location where life could be found in our Solar System is Saturn’s moon Enceladus. It’s perhaps one of the most fascinating of all Saturn’s moons with, just like Europa, it’s thought to have a global ocean beneath an icy crust. Water vapour escapes as jets through cracks in the crust near the south pole. A new study that has been published in Communications Earth & Environment shows how the ocean of Enceladus is separated into distinct layers. These layers impeded the movement of material from the ocean floor, where life is thought to exist, to the surface. 

True-color image of Enceladus’ plumes emanating from its south pole. (Credit: NASA / JPL-Caltech / SSI / Kevin M. Gill)

Spacecraft visiting worlds like Enceladus hunt for traces of chemicals like microbes and organic compounds are searched for among the water spraying out of the surface. However these ocean layers may well break down as they ascend through the ocean. By the time they reach the surface the biological signatures that would have been familiar are unrecognisable. It’s just possible that this process could hide signs of life that exist deep on the floor of the alien oceans. 

Flynn Ames, the lead author of the paper from the University of Reading explains that the oceans behave like oil and water in a jar with the distinct layers resisting vertical mixing. 

“These natural barriers could trap particles and chemical traces of life in the depths below for hundreds to hundreds of thousands of years. Previously, it was thought that these things could make their way efficiently to the ocean top within several months.”

A black smoker hydrothermal vent discovered in the Atlantic Ocean in 1979. It’s fueled from deep beneath the surface by magma that superheats the water. The plume carries minerals and other materials out to the sea. Courtesy USGS.

It seems then that simply sampling the escaping surface waters may not be sufficient to detect signs of life. Computer models have been established that are similar to those used to study our own oceans. The results revealing implications for our search for aliens in our Solar System. We may yet have to do more than simply analyse water spraying through surface cracks and fissures. Missions have been discussed that could launch tiny submarines to explore the oceans beneath the ice. It may be the only way we can find out once and for all if life does exist in the deep waters beneath the icy crusts.

Source : Alien ocean could hide signs of life from spacecraft

The post Alien Oceans May Conceal Signs of Life from Spacecraft appeared first on Universe Today.

Today we have another photo-plus-text contribution from Athayde Tonhasca Júnior; the subject is mangoes, my favorite fruit (and flies, my favorite group of insects). Athayde’s text is indented, and you can click on the photos to enlarge them.

The king and its flies

Germany has its Pumpkin Festival, Canada celebrates a Cranberry Festival, Spaniards go wild hurling over-ripe tomatoes at each other at the Tomato Festival, while Italians savour their winemaking heritage during the Marino Grape Festival. But among the many fruit- and produce-themed events around the world, few have the cultural magnitude of The International Mango Festival, held annually in Delhi.

Delhi’s mango festival: activities include mango eating competitions, mango quizzes and slogan-writing, mango carving, mango tasting and varieties contests, dances, plays and crafts © India’s Ministry of Tourism.

Mango (Mangifera indica) has been a cultural and religious symbol in India for millennia: grown for over 4,000 years, its earliest references date back to around 2,000 BC from ancient texts and scriptures. The fruit is associated with fertility, prosperity and devotion in Hindu and Buddhist mythologies and traditions. Mangoes symbolise the arrival of summer, appearing in folk songs, literature and art, and are used in religious ceremonies and offerings to the gods. When summer comes, Indians give mangoes to family, friends, customers and employees. The fruit’s flavours, juiciness and texture make it an effective tool for diplomatic relations: mangoes have been routinely offered to foreign dignitaries and were sent as gifts for the coronation of George VI.

The mango is more than an Indian icon: it is one of the most important fruits in tropical and subtropical areas around the world. Mangoes are a main source of vitamin A in Africa and Asia, and the tree’s bark and leaves have been used in folk remedies for centuries. The fruit is mainly eaten in natura, green or ripe, but is also liberally used in chutneys, pickles, curries, preserves, juices, ice-creams and a variety of dishes throughout Asia and Central and South America. Mangoes are grown commercially in more than 100 countries, and 65 of them produce over 1,000 million tonnes each a year. And there’s no problem selling all those fruits: mangoes are rapidly gaining in popularity in temperate countries, so demand is increasing. The cultural, nutritional and economic importance of the mango more than justify its title of ‘the king of fruits’.

The king of fruits. Mangoes sold in Britain don’t do justice to the fruit’s flavours © Obsidian Soul, Wikimedia Commons:

Mango trees produce panicles (branched inflorescences) bearing tiny flowers – and lots of them. A mature tree may have 200 to 3,000 panicles, each with 500 to 10,000 flowers. This abundance may suggest ample opportunities for pollination, but that’s not so. Depending on growing conditions and crop variety, 30 to 80% of flowers are staminate, that is, they lack functional pistils. These flowers are functionally male, therefore incapable of being fertilized. The remaining fertile flowers are vulnerable to a range of environmental stresses such as excessive rain and extremes of temperature that prevent fertilisation. To make things worse, each flower produces little nectar, relatively few pollen grains (200-300), and its stigma (the part that receives the pollen) is too small to be of great efficiency. As a result, up to 60% of the flowers receive no pollen, and a panicle may produce up to three fruits at most.

A mango panicle © Delince, Wikimedia Commons:

A single mango flower is not particularly rewarding, but massive numbers of them entice lots of non-specialised visitors. A range of flies, bees, wasps, butterflies, moths, beetles, ants, bugs and bats drop by for a small sip of nectar from each flower. By hopping from flower to flower, visitors greatly increase the chances of cross pollination – although the wind also plays a part.

Among all the flower visitors, one group makes up some of most efficient pollinators of mango varieties grown around the world: flies, especially blowflies, carrion flies, bluebottles (family Calliphoridae), flesh flies (family Sarcophagidae), hover flies (family Syrphidae), and the house fly (Musca domestica). Except for hover flies, they are not seen in a good light by the public. That’s understandable, since most of what we know about them relates to their roles as agricultural pests and vectors of human and animal diseases. But that’s a narrow take on their comings and goings. These flies, often categorised as “filth flies”, are enormously important as decomposers and recyclers, and are vital for food chains: numerous birds, bats and fish depend on them. Another role is becoming increasingly understood: their contribution to myiophily (or myophily), that is, pollination by flies (Orford et al., 2015).

The unappealingly named oriental latrine fly (Chrysomya megacephala) is an important mango pollinator © portioid, iNaturalist:

Blowflies, flesh flies and the like are relatively large and their bodies are covered with ‘hairs’ (setae), which are important pollen-carrying structures. These flies are abundant and persistent flower visitors throughout the blooming season, all desirable qualities for efficient pollination. Besides mango, blow flies, flesh flies and the house fly are known or suspected to pollinate avocado, blueberry, Brussels sprout, carrot, leek, macadamia, onion and strawberry (Cook et al., 2020). The common greenbottle (Lucilia sericata) and the bluebottle (Calliphora vomitoria) are reared commercially for the pollination of seed crops and vegetable crops, respectively (L. sericata is also reared for medical uses: because their maggots preferentially eat dead tissue, they have been used for the treatment of diabetic ulcers, bedsores and other chronic wounds).

A fly with pollen attached to its back © ninfaj, Maryland Agronomy News:

Mango farmers in Northern Australia hold blow flies in such esteem that some growers have installed ‘stink stations’ in their orchards, a practice also used by avocado farmers in Peru. Each station consists of a plastic container filled with fish or chicken carcasses, a concoction guaranteed to attract flies. It’s not clear whether these contraptions improve yields (Finch et al., 2023), but at any rate, farmers see foul-smelling orchards as a small price to pay for the possibility of bumper crops of juicy, fragrant and profitable mangoes.

‘Stink stations’ used by mango growers in the Northern Territory, Australia © Finch et al., 2023:

The mango is a case study of the ‘other’ pollinators, that is, those outside the better known and celebrated club of bees, hover flies and moths. We may be unenthusiastic about flies that are the happiest on carrion and dung, but that’s a reflection of our aesthetic prejudices. Farmers around the world who deal with the mango’s finicky floral biology are very grateful for those unloved insects that help them produce better and more of the king of fruits.

The Guimaras Mango Festival in the Philippines wouldn’t be so lavish without the contribution of some flies of ill repute © Ranieljosecastaneda, Wikimedia Commons:

Australopithecus came before us, but that doesn't tell us which specific individual species is our ancestor. The fossil record is spotty in places, but the latest finds could give us enough clues to pin down how we are linked

[An immediate continuation of Part 1, which you should definitely read first; today’s post is not stand-alone.]

The Asymmetry Between Location and Motion

We are in the middle of trying to figure out if the electron (or other similar object) could possibly be of infinitesimal size, to match the naive meaning of the words “elementary particle.” In the last post, I described how 1920’s quantum physics would envision an electron (or other object) in a state |P0> of definite momentum or a state |X0> of definite position (shown in Figs. 1 and 2 from last time.)

If it is meaningful to say that “an electron is really is an object whose diameter is zero”, we would naturally expect to be able to put it into a state in which its position is clearly defined and located at some specific point X0 — namely, we should be able to put it into the state |X0>. But do such states actually exist?

Symmetry and Asymmetry

In Part 1 we saw all sorts of symmetry between momentum and position:

• the symmetry between x and p in the Heisenberg uncertainty principle,
• the symmetry between the states |X0> and |P0>,
• the symmetry seen in their wave functions as functions of x and p shown in Figs. 1 and 2 (and see also 1a and 2a, in the side discussion, for more symmetry.)

This symmetry would seem to imply that if we could put any object, including an elementary particle, in the state |P0>, we ought to be able to put it into a state |X0>, too.

But this logic won’t follow, because in fact there’s an even more important asymmetry. The states |X0> and |P0> differ crucially. The difference lies in their energy.

Who cares about energy?

There are a couple of reasons we should care, closely related. First, just as there is a relationship between position and momentum, there is a relationship between time and energy: energy is deeply related to how wave functions evolve over time. Second, energy has its limits, and we’re going to see them violated.

Energy and How Wave Functions Change Over Time

In 1920s quantum physics, the evolution of our particle’s wave function depends on how much energy it has… or, if its energy is not definite, on the various possible energies that it may have.

Definite Momentum and Energy: Simplicity

This change with time is simple for the state |P0>, because this state, with definite momentum, also has definite energy. It therefore evolves in a very simple way: it keeps its shape, but moves with a constant speed.

Figure 5: In the state |P0>, shown in Fig. 1 of Part 1, the particle has definite momentum and energy and moves steadily at constant speed; the particle’s position is completely unknown at all times.

How much energy does it have? Well, in 1920s quantum physics, just as in pre-1900 physics, the motion-energy E of an isolated particle of definite momentum p is

• E = p2/2m

where m is the particle’s mass. Where does this formula come from? In first-year university physics, we learn that a particle’s momentum is mv and that its motion-energy is mv2/2 = (mv)2/2m = p2/2m; so in fact this is a familiar formula from centuries ago.

Less Definite Momentum and Energy: Greater Complexity

What about the compromise states mentioned in Part 1, the ones that lie somewhere between the extreme states |X0> and |P0>, in which the particle has neither definite position nor definite momentum? These “Gaussian wave packets” appeared in Fig. 3 and 4 of Part 1. The state of Fig. 3 has less definite momentum than the |P0> state, but unlike the latter, it has a rough location, albeit broadly spread out. How does it evolve?

As seen in Fig. 6, the wave still moves to the left, like the |P0> state. But this motion is now seen not only in the red and blue waves which represent the wave function itself but also in the probability for where to find the particle’s position, shown in the black curve. Our knowledge of the position is poor, but we can clearly see that the particle’s most likely position moves steadily to the left.

Figure 6: In a state with less definite momentum than |P0>, as shown in Fig. 3 of Part 1, the particle has less definite momentum and energy, but its position is roughly known, and its most likely position moves fairly steadily at near-constant speed. If we watched the wave function for a long time, it would slowly spread out.

What happens if the particle’s position is better known and the momentum is becoming quite uncertain? We saw what a wave function for such a particle looks like in Fig. 4 of Part 1, where the position is becoming quite well known, but nowhere as precisely as in the |X0> state. How does this wave function evolve over time? This is shown in Fig. 7.

Figure 7: In a state with better known position, shown in Fig. 4 of Part 1, the particle’s position is initially well known but becomes less and less certain over time, as its indefinite momentum and energy causes it to move away from its initial position at a variety of possible speeds.

We see the wave function still indicates the particle is moving to the left. But the wave function spreads out rapidly, meaning that our knowledge of its position is quickly decreasing over time. In fact, if you look at the right edge of the wave function, it has barely moved at all, so the particle might be moving slowly. But the left edge has disappeared out of view, indicating that the particle might be moving very rapidly. Thus the particle’s momentum is indeed very uncertain, and we see this in the evolution of the state.

This uncertainty in the momentum means that we have increased uncertainty in the particle’s motion-energy. If it is moving slowly, its motion-energy is low, while if it is moving rapidly, its motion-energy is much higher. If we measure its motion-energy, we might find it anywhere in between. This is why its evolution is so much more complex than that seen in Fig. 5 and even Fig. 6.

Near-Definite Position: Breakdown

What happens as we make the particle’s position better and better known, approaching the state |X0> that we want to put our electron in to see if it can really be thought of as a true particle within the methods of 1920s quantum physics?

Well, look at Fig. 8, which shows the time-evolution of a state almost as narrow as |X0> .

Figure 8: the time-evolution of a state almost as narrow as |X0>.

Now we can’t even say if the particle is going to the left or to the right! It may be moving extremely rapidly, disappearing off the edges of the image, or it may remain where it was initially, hardly moving at all. Our knowledge of its momentum is basically nil, as the uncertainty principle would lead us to expect. But there’s more. Even though our knowledge of the particle’s position is initially excellent, it rapidly degrades, and we quickly know nothing about it.

We are seeing the profound asymmetry between position and momentum:

• a particle of definite momentum can retain that momentum for a long time,
• a particle of definite position immediately becomes one whose position is completely unknown.

Worse, the particle’s speed is completely unknown, which means it can be extremely high! How high can it go? Well, the closer we make the initial wave function to that of the state |X0>, the faster the particle can potentially move away from its initial position — until it potentially does so in excess of the cosmic speed limit c (often referred to as the “speed of light”)!

That’s definitely bad. Once our particle has the possibility of reaching light speed, we need Einstein’s relativity. But the original quantum methods of Heisenberg-Born-Jordan and Schrödinger do not account for the cosmic speed limit. And so we learn: in the 1920s quantum physics taught in undergraduate university physics classes, a state of definite position simply does not exist.

Isn’t it Relatively Easy to Resolve the Problem?

But can’t we just add relativity to 1920s quantum physics, and then this problem will take care of itself?

You might think so. In 1928, Dirac found a way to combine Einstein’s relativity with Schrödinger’s wave equation for electrons. In this case, instead of the motion-energy of a particle being E = p2/2m, Dirac’s equation focuses on the total energy of the particle. Written in terms of the particle’s rest mass m [which is the type of mass that doesn’t change with speed], that total energy satisfies the equation

For stationary particles, which have p=0, this equation reduces to E=mc2, as it must.

This does indeed take care of the cosmic speed limit; our particle no longer breaks it. But there’s no cosmic momentum limit; even though v has a maximum, p does not. In Einstein’s relativity, the relation between momentum and speed isn’t p=mv anymore. Instead it is

which gives the old formula when v is much less than c, but becomes infinite as v approaches c.

Not that there’s anything wrong with that; momentum can be as large as one wants. The problem is that, as you can see for the formula for energy above, when p goes to infinity, so does E. And while that, too, is allowed, it causes a severe crisis, which I’ll get to in a moment.

Actually, we could have guessed from the start that the energy of a particle in a state of definite position |X0> would be arbitrarily large. The smaller is the position uncertainty Δx, the larger is the momentum uncertainty Δp; and once we have no idea what the particle’s momentum is, we may find that it is huge — which in turn means its energy can be huge too.

Notice the asymmetry. A particle with very small Δp must have very large Δx, but having an unknown location does not affect an isolated particle’s energy. But a particle with very small Δx must have very large Δp, which inevitably means very large energy.

The Particle(s) Crisis

So let’s try to put an isolated electron into a state |X0>, knowing that the total energy of the electron has some probability of being exceedingly high. In particular, it may be much, much larger — tens, or thousands, or trillions of times larger — than mc2 [where again m means the “rest mass” or “invariant mass” of the particle — the version of mass that does not change with speed.]

The problem that cannot be avoided first arises once the energy reaches 3mc2 . We’re trying to make a single electron at a definite location. But how can we be sure that 3mc2 worth of energy won’t be used by nature in another way? Why can’t nature use it to make not only an electron but also a second electron and a positron? [Positrons are the anti-particles of electrons.] If stationary, each of the three particles would require mc2 for its existence.

If electrons (not just the electron we’re working with, but electrons in general) didn’t ever interact with anything, and were just incredibly boring, inert objects, then we could keep this from happening. But not only would this be dull, it simply isn’t true in nature. Electrons do interact with electromagnetic fields, and with other things too. As a result, we can’t stop nature from using those interactions and Einstein’s relativity to turn 3mc2 of energy into three slow particles — two electrons and a positron — instead of one fast particle!

For the state |X0> with Δx = 0 and Δp = infinity, there’s no limit to the energy; it could be 3mc2, 11mc2, 13253mc2, 9336572361mc2. As many electron/positron pairs as we like can join our electron. The |X0> state we have ended up with isn’t at all like the one we were aiming for; it’s certainly not going to be a single particle with a definite location.

Our relativistic version of 1920s quantum physics simply cannot handle this proliferation. As I’ve emphasized, an isolated physical system has only one wave function, no matter how many particles it has, and that wave function exists in the space of possibilities. How big is that space of possibilities here?

Normally, if we have N particles moving in d dimensions of physical space, then the space of possibilities has N-times-d dimensions. (In examples that I’ve given in this post and this one, I had two particles moving in one dimension, so the space of possibilities was 2×1=2 dimensional.) But here, N isn’t fixed. Our state |X0> might have one particle, three, seventy one, nine thousand and thirteen, and so on. And if these particles are moving in our familiar three dimensions of physical space, then the space of possibilities is 3 dimensional if there is one particle, 9 dimensional if there are three particles, 213 dimensional if there are seventy-one particles — or said better, since all of these values of N are possible, our wave function has to simultaneously exist in all of these dimensional spaces at the same time, and tell us the probability of being in one of these spaces compared to the others.

Still worse, we have neglected the fact that electrons can emit photons — particles of light. Many of them are easily emitted. So on top of everything else, we need to include arbitrary numbers of photons in our |X0> state as well.

Good Heavens. Everything is completely out of control.

How Small Can An Electron Be (In 1920s Quantum Physics?)

How small are we actually able to make an electron’s wave function before the language of the 1920s completely falls apart? Well, for the wave function describing the electron to make sense,

• its motion-energy must be below mc2, which means that
• p has to be small compared to mc , which means that
• Δp has to be small compared to mc , which means that
• by Heisenberg’s uncertainty principle, Δx has to be large compared to h/(4πmc)

This distance (up to the factor of 1/4π) is known as a particle’s Compton wavelength, and it is about 10-13 meters for an electron. That’s about 1/1000 of the distance across an atom, but 100 times the diameter of a small atomic nucleus. Therefore, 1920s quantum physics can describe electrons whose wave functions allow them to range across atoms, but cannot describe an electron restricted to a region the size of an atomic nucleus, or of a proton or neutron, whose size is 10-15 meters. It certainly can’t handle an electron restricted to a point!

Let me reiterate: an electron cannot be restricted to a region the size of a proton and still be described by “quantum mechanics”.

As for neutrinos, it’s much worse; since their masses are much smaller, they can’t even be described in regions whose diameter is that of a thousand atoms!

The Solution: Relativistic Quantum Field Theory

It took scientists two decades (arguably more) to figure out how to get around this problem. But with benefit of hindsight, we can say that it’s time for us to give up on the quantum physics of the 1920s, and its image of an electron as a dot — as an infinitesimally small object. It just doesn’t work.

Instead, we now turn to relativistic quantum field theory, which can indeed handle all this complexity. It does so by no longer viewing particles as fundamental objects with infinitesimal size, position x and momentum p, and instead seeing them as ripples in fields. A quantum field can have any number of ripples — i.e. as many particles and anti-particles as you want, and more generally an indefinite number. Along the way, quantum field theory explains why every electron is exactly the same as every other. There is no longer symmetry between x and p, no reason to worry about why states of definite momentum exist and those of definite position do not, and no reason to imagine that “particles” [which I personally think are more reasonably called “wavicles“, since they behave much more like waves than particles] have a definite, unchanging shape.

The space of possibilities is now the space of possible shapes for the field, which always has an infinite number of dimensions — and indeed the wave function of a field (or of multiple fields) is a function of an infinite number of variables (really a function of a function [or of multiple functions], called a “functional”).

Don’t get me wrong; quantum field theory doesn’t do all this in a simple way. As physicists tried to cope with the difficult math of quantum field theory, they faced many serious challenges, including apparent infinities everywhere and lots of consistency requirements that needed to be understood. Nevertheless, over the past seven decades, they solved the vast majority of these problems. As they did so, field theory turned out to agree so well with data that it has become the universal modern language for describing the bricks and mortar of the universe.

Yet this is not the end of the story. Even within quantum field theory, we can still find ways to define what we mean by the “size” of a particle, though doing so requires a new approach. Armed with this definition, we do now have clear evidence that electrons are much smaller than protons. And so we can ask again: can an elementary “particle” [wavicle] have zero size?

We’ll return to this question in later posts.