Tag: The Conversation

Black holes

How black holes challenge our technological world.

I had no idea until reading this recent article that distant black holes are essential for measuring accurately where we are. Have a read.

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Scientists look to black holes to know exactly where we are in the Universe. But phones and wifi are blocking the view

ESA / Hubble / L. Calçada (ESO), CC BY

Lucia McCallum, University of Tasmania

The scientists who precisely measure the position of Earth are in a bit of trouble. Their measurements are essential for the satellites we use for navigation, communication and Earth observation every day.

But you might be surprised to learn that making these measurements – using the science of geodesy – depends on tracking the locations of black holes in distant galaxies.

The problem is, the scientists need to use specific frequency lanes on the radio spectrum highway to track those black holes.

And with the rise of wifi, mobile phones and satellite internet, travel on that highway is starting to look like a traffic jam.

Why we need black holes

Satellites and the services they provide have become essential for modern life. From precision navigation in our pockets to measuring climate change, running global supply chains and making power grids and online banking possible, our civilisation cannot function without its orbiting companions.

To use satellites, we need to know exactly where they are at any given time. Precise satellite positioning relies on the so-called “global geodesy supply chain”.

This supply chain starts by establishing a reliable reference frame as a basis for all other measurements. Because satellites are constantly moving around Earth, Earth is constantly moving around the Sun, and the Sun is constantly moving through the galaxy, this reference frame needs to be carefully calibrated via some relatively fixed external objects.

As it turns out, the best anchor points for the system are the black holes at the hearts of distant galaxies, which spew out streams of radiation as they devour stars and gas.

These black holes are the most distant and stable objects we know. Using a technique called very long baseline interferometry, we can use a network of radio telescopes to lock onto the black hole signals and disentangle Earth’s own rotation and wobble in space from the satellites’ movement.

Different lanes on the radio highway

We use radio telescopes because we want to detect the radio waves coming from the black holes. Radio waves pass cleanly through the atmosphere and we can receive them during day and night and in all weather conditions.

Radio waves are also used for communication on Earth – including things such as wifi and mobile phones. The use of different radio frequencies – different lanes on the radio highway – is closely regulated, and a few narrow lanes are reserved for radio astronomy.

However, in previous decades the radio highway had relatively little traffic. Scientists commonly strayed from the radio astronomy lanes to receive the black hole signals.

To reach the very high precision needed for modern technology, geodesy today relies on more than just the lanes exclusively reserved for astronomy.

Radio traffic on the rise

In recent years, human-made electromagnetic pollution has vastly increased. When wifi and mobile phone services emerged, scientists reacted by moving to higher frequencies.

However, they are running out of lanes. Six generations of mobile phone services (each occupying a new lane) are crowding the spectrum, not to mention internet connections directly sent by a fleet of thousands of satellites.

Today, the multitude of signals are often too strong for geodetic observatories to see through them to the very weak signals emitted by black holes. This puts many satellite services at risk.

What can be done?

To keep working into the future – to maintain the services on which we all depend – geodesy needs some more lanes on the radio highway. When the spectrum is divided up via international treaties at world radio conferences, geodesists need a seat at the table.

Other potential fixes might include radio quiet zones around our essential radio telescopes. Work is also underway with satellite providers to avoid pointing radio emissions directly at radio telescopes.

Any solution has to be global. For our geodetic measurements, we link radio telescopes together from all over the world, allowing us to mimic a telescope the size of Earth. The radio spectrum is primarily regulated by each nation individually, making this a huge challenge.

But perhaps the first step is increasing awareness. If we want satellite navigation to work, our supermarkets to be stocked and our online money transfers arriving safely, we need to make sure we have a clear view of those black holes in distant galaxies – and that means clearing up the radio highway.

Lucia McCallum, Senior Scientist in Geodesy, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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The last paragraph of Lucia’s article is key, in my opinion. Hopefully me posting this article will assist in the task of increasing awareness,

What makes us happy?

It is seemingly a simple question but in practice not so.

Listening to danger or telling others of a danger is a very ancient practice. For it is better to share a potential danger than not to. It was easy to look this up:

Modern sense of “risk, peril, exposure to injury, loss, pain, etc.” (from being in the control of someone or something else) evolved first in French and was in English by late 14c. For this, Old English had pleoh; in early Middle English this sense is found in peril. For sound changes, compare dungeon, which is from the same source.

Thus a post on The Conversation that was about happiness caught my eye.

I am delighted to share it with you.

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Philly psychology students map out local landmarks and hidden destinations where they feel happiest

Rittenhouse Square Park in Center City made it onto the Philly Happiness Map. Matthew Lovette/Jumping Rocks/Universal Images Group via Getty Images

Eric Zillmer, Drexel University

What makes you happy? Perhaps a good night’s sleep, or a wonderful meal with friends?

I am the director of the Happiness Lab at Drexel University, where I also teach a course on happiness. The Happiness Lab is a think tank that investigates the ingredients that contribute to people’s happiness.

Often, my students ask me something along the lines of, “Dr. Z, tell us one thing that will make us happier.”

As a first step, I advise them to spend more time outside.

Achieving lasting and sustainable happiness is more complicated. Research on the happiest countries in the world and the places where people live the longest, known as Blue Zones, shows a common thread: Residents feel they are part of something larger than themselves, such as a community or a city.

So if you’re living in a metropolis like Philadelphia, where, incidentally, the iconic pursuit of happiness charge was ratified in the Declaration of Independence, I believe urban citizenship – that is, forming an identity with your urban surroundings – should also be on your list.

A small boat floats in blue-green waters in front of a picturesque village.
The Greek island of Ikaria in the Aegean Sea is a Blue Zone famous for its residents’ longevity. Nicolas Economou/NurPhoto via Getty Images

Safety, social connection, beauty

Carl Jung, the renowned Swiss psychoanalyst, wrote extensively about the relationship between our internal world and our external environment.

He believed that this relationship was crucial to our psychological well-being.

More recent research in neuroscience and functional imaging has revealed a vast, intricate and complex neurological architecture underlying our psychological perception of a place. Numerous neurological pathways and functional loops transform a complex neuropsychological process into a simple realization: I am happy here!

For example, a happy place should feel safe.

The country of Croatia, a tourist haven for its beauty and culinary delights, is also one of the top 20 safest countries globally, according to the 2025 Global Peace Index.

The U.S. ranks 128th.

The availability of good food and drink can also be a significant factor in creating a happy place.

However, according to American psychologist Abraham Maslow, a pioneer in the field of positive psychology, the opportunity for social connectivity, experiencing something meaningful and having a sense of belonging is more crucial.

Furthermore, research on happy places suggests that they are beautiful. It should not come as a surprise that the happiest places in the world are also drop-dead gorgeous, such as the Indian Ocean archipelago of Mauritius, which is the happiest country in Africa, according to the 2025 World Happiness Report from the University of Oxford and others.

Happy places often provide access to nature and promote active lifestyles, which can help relieve stress. The residents of the island of Ikaria in Greece, for example, one of the original Blue Zones, demonstrate high levels of physical activity and social interaction.

A Google map display on right with a list of mapped locations on the left.
A map of 28 happy places in Philadelphia, based on 243 survey responses from Drexel students. The Happiness Lab at Drexel University

Philly Happiness Map

I asked my undergraduate psychology students at Drexel, many of whom come from other cities, states and countries, to pick one place in Philadelphia where they feel happy.

From the 243 student responses, the Happiness Lab curated 28 Philly happy places, based on how frequently the places were endorsed and their accessibility.

Philadelphia’s founder, William Penn, would likely approve that Rittenhouse Square Park and three other public squares – Logan, Franklin and Washington – were included. These squares were vital to Penn’s vision of landscaped public parks to promote the health of the mind and body by providing “salubrious spaces similar to the private garden.” They are beautiful and approachable, serving as “places to rest, take a pause, work, or read a book,” one student told us.

Places such as the Philadelphia Zoo, Penn’s Landing and the Philadelphia Museum of Art are “joyful spots that are fun to explore, and one can also take your parents along if need be,” as another student described.

The Athenaeum of Philadelphia, a historic library with eclectic programming, feels to one student like “coming home, a perfect third place.”

Some students mentioned happy places that are less known. These include tucked-away gardens such as the John F. Collings Park at 1707 Chestnut St., the rooftop Cira Green at 129 S. 30th St. and the James G. Kaskey Memorial Park and BioPond at 433 S. University Ave.

A stone-lined brick path extends through a nicely landscaped outdoor garden area.
The James G. Kaskey Memorial Park and BioPond in West Philadelphia is an urban oasis. M. Fischetti for Visit Philadelphia

My students said these are small, unexpected spots that provide an excellent opportunity for a quiet, peaceful break, to be present, whether enjoyed alone or with a friend. I checked them out and I agree.

The students also mentioned places I had never heard of even though I’ve lived in the city for over 30 years.

The “cat park” at 526 N. Natrona St. in Mantua is a quiet little park with an eclectic personality and lots of friendly cats.

Mango Mango Dessert at 1013 Cherry St. in Chinatown, which is a frequently endorsed happiness spot among the students because of its “bustling streets, lively atmosphere and delicious food,” is a perfect pit stop for mango lovers. And Maison Sweet, at 2930 Chestnut St. in University City, is a casual bakery and cafe “where you may end up staying longer than planned,” one student shared.

I find that Philly’s happy places, as seen through the eyes of college students, tend to offer a space for residents to take time out from their day to pause, reset, relax and feel more connected and in touch with the city.

Happiness principals are universal, yet our own journeys are very personal. Philadelphians across the city may have their own list of happy places. There are really no right or wrong answers. If you don’t have a personal happy space, just start exploring and you may be surprised what you will find, including a new sense of happiness.

See the full Philly Happiness Map list here, and visit the exhibit at the W.W. Hagerty Library at Drexel University to learn more.

Read more of our stories about Philadelphia.

Eric Zillmer, Professor of Neuropsychology, Drexel University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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For me, an Englishman living in Oregon, feeding the wild deer each morning gives me untold joy and happiness. It is my ‘personal happy space’.

So thank you, Prof. Zillmer, for writing this.

The mystery of Dark Matter

This very interesting article is worth a read.

Patrice Ayme published a post on Wednesday, 25th June, 2025 that is deeply conected to the following post from The Conversation.

His post was called: ‘How Does The Universe Expand? The Way Cosmologists Decided That It Does, FLRW Metric! A Causal Loop Is At The Heart Of Modern ΛCDM Cosmology!’

Thus I recommend that you read that article and then the one that is republished by me, with permission, from The Conversation.

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The Vera C. Rubin Observatory will help astronomers investigate dark matter, continuing the legacy of its pioneering namesake

The Rubin Observatory is scheduled to release its first images in 2025. RubinObs/NOIRLab/SLAC/NSF/DOE/AURA/B. Quint

Samantha Thompson, Smithsonian Institution

Everything in space – from the Earth and Sun to black holes – accounts for just 15% of all matter in the universe. The rest of the cosmos seems to be made of an invisible material astronomers call dark matter.

Astronomers know dark matter exists because its gravity affects other things, such as light. But understanding what dark matter is remains an active area of research.

With the release of its first images this month, the Vera C. Rubin Observatory has begun a 10-year mission to help unravel the mystery of dark matter. The observatory will continue the legacy of its namesake, a trailblazing astronomer who advanced our understanding of the other 85% of the universe.

As a historian of astronomy, I’ve studied how Vera Rubin’s contributions have shaped astrophysics. The observatory’s name is fitting, given that its data will soon provide scientists with a way to build on her work and shed more light on dark matter.

Wide view of the universe

From its vantage point in the Chilean Andes mountains, the Rubin Observatory will document everything visible in the southern sky. Every three nights, the observatory and its 3,200 megapixel camera will make a record of the sky.

This camera, about the size of a small car, is the largest digital camera ever built. Images will capture an area of the sky roughly 45 times the size of the full Moon. With a big camera with a wide field of view, Rubin will produce about five petabytes of data every year. That’s roughly 5,000 years’ worth of MP3 songs.

After weeks, months and years of observations, astronomers will have a time-lapse record revealing anything that explodes, flashes or moves – such as supernovas, variable stars or asteroids. They’ll also have the largest survey of galaxies ever made. These galactic views are key to investigating dark matter.

Galaxies are the key

Deep field images from the Hubble Space Telescope, the James Webb Space Telescope and others have visually revealed the abundance of galaxies in the universe. These images are taken with a long exposure time to collect the most light, so that even very faint objects show up.

Researchers now know that those galaxies aren’t randomly distributed. Gravity and dark matter pull and guide them into a structure that resembles a spider’s web or a tub of bubbles. The Rubin Observatory will expand upon these previous galactic surveys, increasing the precision of the data and capturing billions more galaxies.

In addition to helping structure galaxies throughout the universe, dark matter also distorts the appearance of galaxies through an effect referred to as gravitational lensing.

Light travels through space in a straight line − unless it gets close to something massive. Gravity bends light’s path, which distorts the way we see it. This gravitational lensing effect provides clues that could help astronomers locate dark matter. The stronger the gravity, the bigger the bend in light’s path.

Many galaxies, represented as bright dots, some blurred, against a dark background.
The white galaxies seen here are bound in a cluster. The gravity from the galaxies and the dark matter bends the light from the more distant galaxies, creating contorted and magnified images of them. NASA, ESA, CSA and STScI

Discovering dark matter

For centuries, astronomers tracked and measured the motion of planets in the solar system. They found that all the planets followed the path predicted by Newton’s laws of motion, except for Uranus. Astronomers and mathematicians reasoned that if Newton’s laws are true, there must be some missing matter – another massive object – out there tugging on Uranus. From this hypothesis, they discovered Neptune, confirming Newton’s laws.

With the ability to see fainter objects in the 1930s, astronomers began tracking the motions of galaxies.

California Institute of Technology astronomer Fritz Zwicky coined the term dark matter in 1933, after observing galaxies in the Coma Cluster. He calculated the mass of the galaxies based on their speeds, which did not match their mass based on the number of stars he observed.

He suspected that the cluster could contain an invisible, missing matter that kept the galaxies from flying apart. But for several decades he lacked enough observational evidence to support his theory.

A woman adjusting a large piece of equipment.
Vera Rubin operates the Carnegie spectrograph at Kitt Peak National Observatory in Tucson. Carnegie Institution for Science, CC BY

Enter Vera Rubin

In 1965, Vera Rubin became the first women hired onto the scientific staff at the Carnegie Institution’s Department of Terrestrial Magnetism in Washington, D.C.

She worked with Kent Ford, who had built an extremely sensitive spectrograph and was looking to apply it to a scientific research project. Rubin and Ford used the spectrograph to measure how fast stars orbit around the center of their galaxies.

In the solar system, where most of the mass is within the Sun at the center, the closest planet, Mercury, moves faster than the farthest planet, Neptune.

“We had expected that as stars got farther and farther from the center of their galaxy, they would orbit slower and slower,” Rubin said in 1992.

What they found in galaxies surprised them. Stars far from the galaxy’s center were moving just as fast as stars closer in.

“And that really leads to only two possibilities,” Rubin explained. “Either Newton’s laws don’t hold, and physicists and astronomers are woefully afraid of that … (or) stars are responding to the gravitational field of matter which we don’t see.”

Data piled up as Rubin created plot after plot. Her colleagues didn’t doubt her observations, but the interpretation remained a debate. Many people were reluctant to accept that dark matter was necessary to account for the findings in Rubin’s data.

Rubin continued studying galaxies, measuring how fast stars moved within them. She wasn’t interested in investigating dark matter itself, but she carried on with documenting its effects on the motion of galaxies.

A quarter with a woman looking upwards engraved onto it.
A U.S quarter honors Vera Rubin’s contributions to our understanding of dark matter. United States Mint, CC BY

Vera Rubin’s legacy

Today, more people are aware of Rubin’s observations and contributions to our understanding of dark matter. In 2019, a congressional bill was introduced to rename the former Large Synoptic Survey Telescope to the Vera C. Rubin Observatory. In June 2025, the U.S. Mint released a quarter featuring Vera Rubin.

Rubin continued to accumulate data about the motions of galaxies throughout her career. Others picked up where she left off and have helped advance dark matter research over the past 50 years.

In the 1970s, physicist James Peebles and astronomers Jeremiah Ostriker and Amos Yahil created computer simulations of individual galaxies. They concluded, similarly to Zwicky, that there was not enough visible matter in galaxies to keep them from flying apart.

They suggested that whatever dark matter is − be it cold stars, black holes or some unknown particle − there could be as much as 10 times the amount of dark matter than ordinary matter in galaxies.

Throughout its 10-year run, the Rubin Observatory should give even more researchers the opportunity to add to our understanding of dark matter.

Samantha Thompson, Astronomy Curator, National Air and Space Museum, Smithsonian Institution

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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It is difficult to say anything more as my comment will mean practically nothing compared to Patrice Ayme and Samantha Thompson.

I am just grateful that these fine people publish their research with permission for it to be republished elsewhere. Thank you!

The recycling of plastics.

It is not as straightforward as I thought it was.

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How single-stream recycling works − your choices can make it better

Successful recycling requires some care. Alejandra Villa Loarca/Newsday RM via Getty Images

Alex Jordan, University of Wisconsin-Stout

Every week, millions of Americans toss their recyclables into a single bin, trusting that their plastic bottles, aluminum cans and cardboard boxes will be given a new life.

But what really happens after the truck picks them up?

Single-stream recycling makes participating in recycling easy, but behind the scenes, complex sorting systems and contamination mean a large percentage of that material never gets a second life. Reports in recent years have found 15% to 25% of all the materials picked up from recycle bins ends up in landfills instead.

Plastics are among the biggest challenges. Only about 9% of the plastic generated in the U.S. actually gets recycled, according to the Environmental Protection Agency. Some plastic is incinerated to produce energy, but most of the rest ends up in landfills instead.

Photos and arrows show how much of each type of product is recycled.
A breakdown of U.S. recycling by millions of tons shows about two-thirds of all paper and cardboard gets a second life, but only about a third of metal, a quarter of glass and less than 10% of plastics do. Alex Jordan/University of Wisconsin-Stout

So, what makes plastic recycling so difficult? As an engineer whose work focuses on reprocessing plastics, I have been exploring potential solutions.

How does single-stream recycling work?

In cities that use single-stream recycling, consumers put all of their recyclable materials − paper, cardboard, plastic, glass and metal − into a single bin. Once collected, the mixed recyclables are taken to a materials recovery facility, where they are sorted.

First, the mixed recyclables are shredded and crushed into smaller fragments, enabling more effective separation. The mixed fragments pass over rotating screens that remove cardboard and paper, allowing heavier materials, including plastics, metals and glass, to continue along the sorting line.

The basics of a single-stream recycling system in Pennsylvania. Source: Van Dyk Recycling Solutions.

Magnets are used to pick out ferrous metals, such as steel. A magnetic field that produces an electrical current with eddies sends nonferrous metals, such as aluminum, into a separate stream, leaving behind plastics and glass.

The glass fragments are removed from the remaining mix using gravity or vibrating screens.

That leaves plastics as the primary remaining material.

While single-stream recycling is convenient, it has downsides. Contamination, such as food residue, plastic bags and items that can’t be recycled, can degrade the quality of the remaining material, making it more difficult to reuse. That lowers its value.

Having to remove that contamination raises processing costs and can force recovery centers to reject entire batches.

A mound of items send for recycling includes a lot of plastic bags.
Plastic bags, food residue and items that can’t be recycled can contaminate a recycling stream. City of Greenville, N.C./Flickr

Which plastics typically can’t be recycled?

Each recycling program has rules for which items it will and won’t take. You can check which items can and cannot be recycled for your specific program on your municipal page. Often, that means checking the recycling code stamped on the plastic next to the recycling icon.

These are the toughest plastics to recycle and most likely to be excluded in your local recycling program:

  • Symbol 3 – Polyvinyl chloride, or PVC, found in pipes, shower curtains and some food packaging. It may contain harmful additives such as phthalates and heavy metals. PVC also degrades easily, and melting can release toxic fumes during recycling, contaminating other materials and making it unsafe to process in standard recycling facilities.
  • Symbol 4 – Low-density polyethylene, or LDPE, is often used in plastic bags and shrink-wrap. Because it’s flexible and lightweight, it’s prone to getting tangled in sorting machinery at recycling plants.
  • Symbol 6 – Polystyrene, often used in foam cups, takeout containers and packing peanuts. Because it’s lightweight and brittle, it’s difficult to collect and process and easily contaminates recycling streams.

Which plastics to include

That leaves three plastics that can be recycled in many facilities:

However, these aren’t accepted in some facilities for reasons I’ll explain.

Taking apart plastics, bead by bead

Some plastics can be chemically recycled or ground up for reprocessing, but not all plastics play well together.

Simple separation methods, such as placing ground-up plastics in water, can easily remove your soda bottle plastic (PET) from the mixture. The ground-up PET sinks in water due to the plastic’s density. However, HDPE, used in milk jugs, and PP, found in yogurt cups, both float, and they can’t be recycled together. So, more advanced and expensive technology, such as infrared spectroscopy, is often required to separate those two materials.

Once separated, the plastic from your soda bottle can be chemically recycled through a process called solvolysis.

It works like this: Plastic materials are formed from polymers. A polymer is a molecule with many repeating units, called monomers. Picture a pearl necklace. The individual pearls are the repeating monomer units. The string that runs through the pearls is the chemical bond that joins the monomer units together. The entire necklace can then be thought of as a single molecule.

During solvolysis, chemists break down that necklace by cutting the string holding the pearls together until they are individual pearls. Then, they string those pearls together again to create new necklaces.

Other chemical recycling methods, such as pyrolysis and gasification, have drawn environmental and health concerns because the plastic is heated, which can release toxic fumes. But chemical recycling also holds the potential to reduce both plastic waste and the need for new plastics, while generating energy.

The problem of yogurt cups and milk jugs

The other two common types of recycled plastics − items such as yogurt cups (PP) and milk jugs (HDPE) − are like oil and water: Each can be recycled through reprocessing, but they don’t mix.

If polyethylene and polypropylene aren’t completely separated during recycling, the resulting mix can be brittle and generally unusable for creating new products.

Chemists are working on solutions that could increase the quality of recycled plastics through mechanical reprocessing, typically done at separate facilities.

One promising mechanical method for recycling mixed plastics is to incorporate a chemical called a compatibilizer. Compatibilizers contain the chemical structure of multiple different polymers in the same molecule. It’s like how lecithin, commonly found in egg yolks, can help mix oil and water to make mayonnaise − part of the lecithin molecule is in the oil phase and part is in the water phase.

In the case of yogurt cups and milk jugs, recently developed block copolymers are able to produce recycled plastic materials with the flexibility of polyethylene and the strength of polypropylene.

Improving recycling

Research like this can make recycled materials more versatile and valuable and move products closer to a goal of a circular economy without waste.

However, improving recycling also requires better recycling habits.

You can help the recycling process by taking a few minutes to wash off food waste, avoiding putting plastic bags in your recycling bin and, importantly, paying attention to what can and cannot be recycled in your area.

Alex Jordan, Associate Professor of Plastics Engineering, University of Wisconsin-Stout

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Can we all learn to be better at recycling in the face of so much world ‘news’!

Our brains and new memories

A fascinating article!

I may be the wrong side of old but I still enjoy immensely the process of learning new things. Some of these new memories actually stay with me!

That is why it gives me great pleasure in republishing an article from The Conversation about our brains creating new memories.

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How does your brain create new memories? Neuroscientists discover ‘rules’ for how neurons encode new information

Neurons that fire together sometimes wire together. PASIEKA/Science Photo Library via Getty Images

William Wright, University of California, San Diego and Takaki Komiyama, University of California, San Diego

Every day, people are constantly learning and forming new memories. When you pick up a new hobby, try a recipe a friend recommended or read the latest world news, your brain stores many of these memories for years or decades.

But how does your brain achieve this incredible feat?

In our newly published research in the journal Science, we have identified some of the “rules” the brain uses to learn.

Learning in the brain

The human brain is made up of billions of nerve cells. These neurons conduct electrical pulses that carry information, much like how computers use binary code to carry data.

These electrical pulses are communicated with other neurons through connections between them called synapses. Individual neurons have branching extensions known as dendrites that can receive thousands of electrical inputs from other cells. Dendrites transmit these inputs to the main body of the neuron, where it then integrates all these signals to generate its own electrical pulses.

It is the collective activity of these electrical pulses across specific groups of neurons that form the representations of different information and experiences within the brain.

Diagram of neuron, featuring a relatively large cell body with a long branching tail extending from it
Neurons are the basic units of the brain. OpenStax, CC BY-SA

For decades, neuroscientists have thought that the brain learns by changing how neurons are connected to one another. As new information and experiences alter how neurons communicate with each other and change their collective activity patterns, some synaptic connections are made stronger while others are made weaker. This process of synaptic plasticity is what produces representations of new information and experiences within your brain.

In order for your brain to produce the correct representations during learning, however, the right synaptic connections must undergo the right changes at the right time. The “rules” that your brain uses to select which synapses to change during learning – what neuroscientists call the credit assignment problem – have remained largely unclear.

Defining the rules

We decided to monitor the activity of individual synaptic connections within the brain during learning to see whether we could identify activity patterns that determine which connections would get stronger or weaker.

To do this, we genetically encoded biosensors in the neurons of mice that would light up in response to synaptic and neural activity. We monitored this activity in real time as the mice learned a task that involved pressing a lever to a certain position after a sound cue in order to receive water.

We were surprised to find that the synapses on a neuron don’t all follow the same rule. For example, scientists have often thought that neurons follow what are called Hebbian rules, where neurons that consistently fire together, wire together. Instead, we saw that synapses on different locations of dendrites of the same neuron followed different rules to determine whether connections got stronger or weaker. Some synapses adhered to the traditional Hebbian rule where neurons that consistently fire together strengthen their connections. Other synapses did something different and completely independent of the neuron’s activity.

Our findings suggest that neurons, by simultaneously using two different sets of rules for learning across different groups of synapses, rather than a single uniform rule, can more precisely tune the different types of inputs they receive to appropriately represent new information in the brain.

In other words, by following different rules in the process of learning, neurons can multitask and perform multiple functions in parallel.

Future applications

This discovery provides a clearer understanding of how the connections between neurons change during learning. Given that most brain disorders, including degenerative and psychiatric conditions, involve some form of malfunctioning synapses, this has potentially important implications for human health and society.

For example, depression may develop from an excessive weakening of the synaptic connections within certain areas of the brain that make it harder to experience pleasure. By understanding how synaptic plasticity normally operates, scientists may be able to better understand what goes wrong in depression and then develop therapies to more effectively treat it.

Microscopy image of mouse brain cross-section with lower middle-half dusted green
Changes to connections in the amygdala – colored green – are implicated in depression. William J. Giardino/Luis de Lecea Lab/Stanford University via NIH/Flickr, CC BY-NC

These findings may also have implications for artificial intelligence. The artificial neural networks underlying AI have largely been inspired by how the brain works. However, the learning rules researchers use to update the connections within the networks and train the models are usually uniform and also not biologically plausible. Our research may provide insights into how to develop more biologically realistic AI models that are more efficient, have better performance, or both.

There is still a long way to go before we can use this information to develop new therapies for human brain disorders. While we found that synaptic connections on different groups of dendrites use different learning rules, we don’t know exactly why or how. In addition, while the ability of neurons to simultaneously use multiple learning methods increases their capacity to encode information, what other properties this may give them isn’t yet clear.

Future research will hopefully answer these questions and further our understanding of how the brain learns.

William Wright, Postdoctoral Scholar in Neurobiology, University of California, San Diego and Takaki Komiyama, Professor of Neurobiology, University of California, San Diego

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Our human brains are incredible. Billions of nerve cells. Yet we are still getting to know the science of our brains and as that last sentence was written: “Future research will hopefully answer these questions and further our understanding of how the brain learns.”

Roll on this future research.

The US decline in butterflies

The natural world is quite remarkable!

This article was published in The Conversation last Thursday, the 6th March, 2025.

Where we live in rural Southern Oregon is glorious and photos of our locale have been published before. However, I wanted to share this article with you all.

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Butterflies declined by 22% in just 2 decades across the US – there are ways you can help save them

The endangered Karner blue butterfly has struggled with habitat loss. U.S. Fish and Wildlife Service

Eliza Grames, Binghamton University, State University of New York

If the joy of seeing butterflies seems increasingly rare these days, it isn’t your imagination.

From 2000 to 2020, the number of butterflies fell by 22% across the continental United States. That’s 1 in 5 butterflies lost. The findings are from an analysis just published in the journal Science by the U.S. Geological Survey’s Powell Center Status of Butterflies of the United States Working Group, which I am involved in.

We found declines in just about every region of the continental U.S. and across almost all butterfly species.

Overall, nearly one-third of the 342 butterfly species we were able to study declined by more than half. Twenty-two species fell by more than 90%. Only nine actually increased in numbers.

An orange butterfly with black webbing and spots sits on a purple flower.
West Coast lady butterflies range across the western U.S., but their numbers have dropped by 80% in two decades. Renee Las Vegas/Wikimedia Commons, CC BY

Some species’ numbers are dropping faster than others. The West Coast lady, a fairly widespread species across the western U.S., dropped by 80% in 20 years. Given everything we know about its biology, it should be doing fine – it has a wide range and feeds on a variety of plants. Yet, its numbers are absolutely tanking across its range.

Why care about butterflies?

Butterflies are beautiful. They inspire people, from art to literature and poetry. They deserve to exist simply for the sake of existing. They are also important for ecosystem function.

Butterflies are pollinators, picking up pollen on their legs and bodies as they feed on nectar from one flower and carrying it to the next. In their caterpillar stage, they also play an important role as herbivores, keeping plant growth in check.

A closeup of a caterpillar eating a leaf.
A pipevine swallowtail caterpillar munches on leaves at Brookside Gardens in Wheaton, Md. Herbivores help keep plant growth in check. Judy Gallagher/Wikimedia Commons, CC BY

Butterflies can also serve as an indicator species that can warn of threats and trends in other insects. Because humans are fond of butterflies, it’s easy to get volunteers to participate in surveys to count them.

The annual North American Butterfly Association Fourth of July Count is an example and one we used in the analysis. The same kind of nationwide monitoring by amateur naturalists doesn’t exist for less charismatic insects such as walking sticks.

What’s causing butterflies to decline?

Butterfly populations can decline for a number of reasons. Habitat loss, insecticides, rising temperatures and drying landscapes can all harm these fragile insects.

A study published in 2024 found that a change in insecticide use was a major factor in driving butterfly declines in the Midwest over 17 years. The authors, many of whom were also part of the current study, noted that the drop coincided with a shift to using seeds with prophylactic insecticides, rather than only spraying crops after an infestation.

The Southwest saw the greatest drops in butterfly abundance of any region. As that region heats up and dries out, the changing climate may be driving some of the butterfly decline there. Butterflies have a high surface-to-volume ratio – they don’t hold much moisture – so they can easily become desiccated in dry conditions. Drought can also harm the plants that butterflies rely on.

Only the Pacific Northwest didn’t lose butterfly population on average. This trend was largely driven by an irruptive species, meaning one with extremely high abundance in some years – the California tortoiseshell. When this species was excluded from the analyses, trends in the Pacific Northwest were similar to other regions.

A butterfly on a leaf
The California tortoiseshell butterfly can look like wood when its wings are closed, but they’re a soft orange on the other side. Walter Siegmund/Wikimedia Commons, CC BY-SA

When we looked at each species by its historical range, we found something else interesting.

Many species suffered their highest losses at the southern ends of their ranges, while the northern losses generally weren’t as severe. While we could not link drivers to trends directly, the reason for this pattern might involve climate change, or greater exposure to agriculture with insecticides in southern areas, or it may be a combination of many stressors.

There is hope for populations to recover

Some butterfly species can have multiple generations per year, and depending on the environmental conditions, the number of generations can vary between years.

This gives me a bit of hope when it comes to butterfly conservation. Because they have such short generation times, even small conservation steps can make a big difference and we can see populations bounce back.

The Karner blue is an example. It’s a small, endangered butterfly that depends on oak savannas and pine barren ecosystems. These habitats are uncommon and require management, especially prescribed burning, to maintain. With restoration efforts, one Karner blue population in the Albany Pine Bush Preserve in New York rebounded from a few hundred individuals in the early 1990s to thousands of butterflies.

Similar management and restoration efforts could help other rare and declining butterflies to recover.

What you can do to help butterflies recover

The magnitude and rate of biodiversity loss in the world right now can make one feel helpless. But while national and international efforts are needed to address the crisis, you can also take small actions that can have quick benefits, starting in your own backyard.

Butterflies love wildflowers, and planting native wildflowers can benefit many butterfly species. The Xerces Society for Invertebrate Conservation has guides recommending which native species are best to plant in which parts of the country. Letting grass grow can help, even if it’s just a strip of grass and wildflowers a couple of feet wide at the back of the yard.

Butterflies on wildflowers in a small garden.
A patch of wildflowers and grasses can become a butterfly garden, like this one in Townsend, Tenn. Chris Light, CC BY-SA

Supporting policies that benefit conservation can also help. In some states, insects aren’t considered wildlife, so state wildlife agencies have their hands tied when it comes to working on butterfly conservation. But those laws could be changed.

The federal Endangered Species Act can also help. The law mandates that the government maintain habitat for listed species. The U.S. Fish and Wildlife Service in December 2024 recommended listing the monarch butterfly as a threatened species. With the new study, we now have population trends for more than half of all U.S. butterfly species, including many that likely should be considered for listing.

With so many species needing help, it can be difficult to know where to start. But the new data can help concentrate conservation efforts on those species at the highest risk.

I believe this study should be a wake-up call about the need to better protect butterflies and other insects – “the little things that run the world.”

Eliza Grames, Assistant Professor of Biological Sciences, Binghamton University, State University of New York

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Thank you, Eliza, for promoting this article.

If only one person is inspired to make the changes Eliza recommends then republishing this article has been a success.

An article on decluttering

And it isn’t all that one might expect!

Jeannie and I are at opposite ends of the scale, so to speak. The older I get the more I want everything in the same place, primarily because I cannot remember where I previously put something.

Jeannie loves putting stuff anywhere because she can recall where it is!

So an article in The Conversation was fascinating.

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Decluttering can be stressful − a clinical psychologist explains how personal values can make it easier

Asking how discarding an item fits with a person’s goals can help them decide whether to keep it. MoMo Productions via Getty Images

Mary E. Dozier, Mississippi State University

I recently helped my mom sort through boxes she inherited when my grandparents passed away. One box was labeled – either ironically or genuinely – “toothpick holders and other treasures.” Inside were many keepsakes from moments now lost to history – although we found no toothpick holders.

My favorite of the items we sorted through was a solitary puzzle piece, an artifact reflecting my late grandmother’s penchant for hiding the final piece to a jigsaw puzzle just to swoop in at the last moment and finish it.

After several hours of reminiscing, my mom and I threw away 90% of what we had sorted.

“Why did I keep this?” is a question I hear frequently, both from my family and friends and from patients. I am a licensed clinical psychologist whose research focuses on the characterization, assessment and treatment of hoarding disorder, particularly for adults 60 years of age or older. As such, I spend a great deal of my time thinking about this question.

What drives the need to keep stuff?

Hoarding disorder is a psychiatric condition defined by urges to save items and difficulty discarding current possessions. For adults with “clinically severe” hoarding disorder, this leads to a level of household clutter that impairs daily functioning and can even create a fire hazard. In my professional experience, however, many adults struggle with clutter even if they do not meet the clinical criteria for hoarding disorder.

Holding on to things that have sentimental value or could be useful in the future is a natural part of growing older. For some people, though, this tendency to hold on to objects grows over time, to the point that they eventually do meet criteria for hoarding disorder. Age-related changes in executive function may help explain the increase in prevalence of hoarding disorder as we get older; increasing difficulty with decision-making in general also affects decisions around household clutter.

The traditional model behind hoarding disorder suggests that difficulty with discarding comes from distress during decision-making. However, my research shows that this may be less true of older adults.

A room full of piles of papers, stacked shelves and a tricycle.
Time to declutter. Kurt Whitman/Education Images via Getty Images

When I was a graduate student, I conducted a study in which we asked adults with hoarding disorder to spend 15 minutes making decisions about whether to keep or discard various items brought from their home. Participants could sort whatever items they wanted. Most chose to sort paper items such as old mail, cards or notes.

We found that age was associated with lower levels of distress during the task, such that participants who were older tended to feel less stressed when making the decision about what to keep and what to discard. We also found that many participants, particularly those who were older, actually reported positive emotions while sorting their items.

In new research publishing soon, my current team replicated this finding using a home-based version of the task. This suggests that fear of making the wrong decision isn’t a universal driver of our urge to save items.

In fact, a study my team published in August 2024 with adults over 50 with hoarding disorder suggests that altruism, a personality trait of wanting to help others, may explain why some people keep items that others might discard. My colleagues and I compared our participants’ personality profiles with that of adults in the general population of the same gender and age group. Compared with the general population, participants with hoarding disorder scored almost universally high on altruism.

Altruism also comes up frequently in my clinical work with older adults who struggle with clutter. People in our studies often tell me that they have held onto something out of a sense of responsibility, either for the item itself or to the environment.

“I need it to go to a good home” and “my grandmother gave this to me” are sentiments we commonly hear. Thus, people may keep things not out of fear of losing them but because saving them is consistent with their values. https://www.youtube.com/embed/JNVjPM1cIbg?wmode=transparent&start=0 Your values can help guide which possessions should stay in your life and which ones should go.

Leaning into values

In a 2024 study, my team demonstrated that taking a values-based approach to decluttering helps older adults to decrease household clutter and increases their positive affect, a state of mind characterized by feelings such as joy and contentment. Clinicians visited the homes of older adults with hoarding disorder for one hour per week for six weeks. At each visit, the clinicians used a technique called motivational interviewing to help participants talk through their decisions while they sorted household clutter.

We found that having participants start with identifying their values allowed them to maintain focus on their long-term goals. Too often, people focus on the immediate ability of an object to “spark joy” and forget to consider whether an object has greater meaning and purpose. Values are the abstract beliefs that we humans use to create our goals. Values are whatever drives us and can include family, faith or frivolity.

Because values are subjective, what people identify as important to keep is also subjective. For example, the dress I wore to my sister’s wedding reminded me of a wonderful day. However, when it no longer fit I gave it away because doing so was more consistent with my values of utility and helpfulness: I wanted the dress to go to someone who needed it and would use it. Someone who more strongly valued family and beauty might have prioritized keeping the dress because of the aesthetics and its link to a family event.

Additionally, we found that instead of challenging the reasons a person might have for keeping an item, it is helpful to instead focus on eliciting their reasons for discarding it and the goals they have for their home and their life.

Tips for sweeping away the old

My research on using motivational interviewing for decluttering and my observations from a current clinical trial on the approach point to some practical steps people can take to declutter their home. Although my work has been primarily with older adults, these tips should be helpful for people of all ages.

Start with writing out your values. Every object in your home should feel value-consistent for you. For example, if tradition and faith are important values for you, you might be more inclined to hold onto a cookbook that was made by the elders at your church and more able to let go of a cookbook you picked up on a whim at a bookstore.

If, instead, health and creativity are your core values, it might be more important to hold onto a cookbook of novel ways to sneak more vegetables into your diet.

Defining value-consistent goals for using your space can help to maintain motivation as you declutter. Are you clearing off your desk so you can work more efficiently? Making space on kitchen counters to bake cookies with your grandchildren?

Remember that sometimes your values will conflict. At those moments, it may help to reflect on whether keeping or discarding an object will bring you closer to your goals for the space.

Similarly, remember that values are subjective. If you are helping a loved one declutter, maintain a curious, nonjudgmental attitude. Where you might see a box filled with junk, your grandmother might see something filled with “toothpick holders and other treasures.”

For additional resources and information on hoarding disorder, visit the International OCD Foundation website.

Mary E. Dozier, Assistant Professor of Psychology, Mississippi State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Prof. Mary Dozier makes some powerful, and cogent, statements in this article. Especially that one’s values are subjective. Nevertheless, I think I should write out my values and see what they tell me.

Our human language!

Namely a universal law.

I was attracted to an article that I read in The Conversation last a week ago.

It also taught me that we humans speak according to Zipf’s Law. I had not previously heard of this law.

So let me republish the article with the full permission of The Conversation.

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Whalesong patterns follow a universal law of human language, new research finds

A humpback whale mother and calf on the New Caledonian breeding grounds. Mark Quintin

Jenny Allen, Griffith University; Ellen Garland, University of St Andrews; Inbal Arnon, Hebrew University of Jerusalem, and Simon Kirby, University of Edinburgh

All known human languages display a surprising pattern: the most frequent word in a language is twice as frequent as the second most frequent, three times as frequent as the third, and so on. This is known as Zipf’s law.

Researchers have hunted for evidence of this pattern in communication among other species, but until now no other examples have been found.

In new research published today in Science, our team of experts in whale song, linguistics and developmental psychology analysed eight years’ of song recordings from humpback whales in New Caledonia. Led by Inbal Arnon from the Hebrew University, Ellen Garland from the University of St Andrews, and Simon Kirby from the University of Edinburgh, We used techniques inspired by the way human infants learn language to analyse humpback whale song.

We discovered that the same Zipfian pattern universally found across human languages also occurs in whale song. This complex signalling system, like human language, is culturally learned by each individual from others.

Learning like an infant

When infant humans are learning, they have to somehow discover where words start and end. Speech is continuous and does not come with gaps between words that they can use. So how do they break into language?

Thirty years of research has revealed that they do this by listening for sounds that are surprising in context: sounds within words are relatively predictable, but between words are relatively unpredictable. We analysed the whale song data using the same procedure.

Photo of a humpback whale breaching from the water.
A breaching humpback whale in New Caledonia. Operation Cetaces

Unexpectedly, using this technique revealed in whale song the same statistical properties that are found in all languages. It turns out both human language and whale song have statistically coherent parts.

In other words, they both contain recurring parts where the transitions between elements are more predictable within the part. Moreover, these recurring sub-sequences we detected follow the Zipfian frequency distribution found across all human languages, and not found before in other species.

Whale song recording (2017) Operation Cetaces 916 KB (download)

A chart showing the different frequencies of sound in whale song.
Close analysis of whale song revealed statistical structures similar to those found in human language. Operation Cetaces

How do the same statistical properties arise in two evolutionarily distant species that differ from one another in so many ways? We suggest we found these similarities because humans and whales share a learning mechanism: culture.

A cultural origin

Our findings raise an exciting question: why would such different systems in such incredibly distant species have common structures? We suggest the reason behind this is that both are culturally learned.

Cultural evolution inevitably leads to the emergence of properties that make learning easier. If a system is hard to learn, it will not survive to the next generation of learners.

There is growing evidence from experiments with humans that having statistically coherent parts, and having them follow a Zipfian distribution, makes learning easier. This suggests that learning and transmission play an important role in how these properties emerged in both human language and whale song.

So can we talk to whales now?

Finding parallel structures between whale song and human language may also lead to another question: can we talk to whales now? The short answer is no, not at all.

Our study does not examine the meaning behind whale song sequences. We have no idea what these segments might mean to the whales, if they mean anything at all.

Photo of whale backs and tails visible above the surface of the sea.
A competitive pod of humpback whales on the New Caledonian breeding grounds. Operation Cetaces

It might help to think about it like instrumental music, as music also contains similar structures. A melody can be learned, repeated, and spread – but that doesn’t give meaning to the musical notes in the same way that individual words have meaning.

Next up: birdsong

Our work also makes a bold prediction: we should find this Zipfian distribution wherever complex communication is transmitted culturally. Humans and whales are not the only species that do this.

We find what is known as “vocal production learning” in an unusual range of species across the animal kingdom. Song birds in particular may provide the best place to look as many bird species culturally learn their songs, and unlike in whales, we know a lot about precisely how birds learn song.

Equally, we expect not to find these statistical properties in the communication of species that don’t transmit complex communication by learning. This will help to reveal whether cultural evolution is the common driver of these properties between humans and whales.

Jenny Allen, Postdoctoral research associate, Griffith University; Ellen Garland, Royal Society University Research Fellow, School of Biology, University of St Andrews; Inbal Arnon, Professor of Psychology, Hebrew University of Jerusalem, and Simon Kirby, Professor of Language Evolution, University of Edinburgh

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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The research scientists have led to a prediction: … we should find this Zipfian distribution wherever complex communication is transmitted culturally. Humans and whales are not the only species that do this.

Fascinating!

Nutrition advice

An article on educating us on avoiding misinformation.

Many articles on nutrition are full of errors and for the lay person there’s no easy way to understand what is correct, or not.

That’s why a recent article appealed to me and I thought it worth sharing.

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Nutrition advice is rife with misinformation − a medical education specialist explains how to tell valid health information from pseudoscience

If a health claim about a dietary intervention sounds too good to be true, it probably is. Mizina/iStock via Getty Images Plus

Aimee Pugh Bernard, University of Colorado Anschutz Medical Campus

The COVID-19 pandemic illuminated a vast landscape of misinformation about many topics, science and health chief among them.

Since then, information overload continues unabated, and many people are rightfully confused by an onslaught of conflicting health information. Even expert advice is often contradictory.

On top of that, people sometimes deliberately distort research findings to promote a certain agenda. For example, trisodium phosphate is a common food additive in cakes and cookies that is used to improve texture and prevent spoilage, but wellness influencers exploit the fact that a similarly named substance is used in paint and cleaning products to suggest it’s dangerous to your health.

Such claims can proliferate quickly, creating widespread misconceptions and undermining trust in legitimate scientific research and medical advice. Social media’s rise as a news and information source further fuels the spread of pseudoscientific views.

Misinformation is rampant in the realm of health and nutrition. Findings from nutrition research is rarely clear-cut because diet is just one of many behaviors and lifestyle factors affecting health, but the simplicity of using food and supplements as a cure-all is especially seductive.

I am an assistant professor specializing in medical education and science communication. I also train scientists and future health care professionals how to communicate their science to the general public.

In my view, countering the voices of social media influencers and health activists promoting pseudoscientific health claims requires leaning into the science of disease prevention. Extensive research has produced a body of evidence-based practices and public health measures that have consistently been shown to improve the health of millions of people around the world. Evaluating popular health claims against the yardstick of this work can help distinguish which ones are based on sound science.

A white person's hands holding a smartphone with screen showing a health app, next to a cup of coffee.
To parse pseudoscientific claims from sound advice about health and nutrition, it’s crucial to evaluate the information’s source. tadamichi/Getty Images

Navigating the terrain of tangled information

Conflicting information can be found on just about everything we eat and drink.

That’s because a food or beverage is rarely just good or bad. Instead, its health effects can depend on everything from the quantity a person consumes to their genetic makeup. Hundreds of scientific studies describe coffee’s health benefits and, on the flip side, its health risks. A bird’s-eye view can point in one direction or another, but news articles and social media posts often make claims based on a single study.

Things can get even more confusing with dietary supplements because people who promote them often make big claims about their health benefits. Take apple cider vinegar, for example – or ACV, if you’re in the know.

Apple cider vinegar has been touted as an all-natural remedy for a variety of ailments, including digestive issues, urinary health and weight management. Indeed, some studies have shown that it might help lower cholesterol, in addition to having other health benefits, but overall those studies have small sample sizes and are inconclusive.

Advocates of this substance often claim that one particular component of it – the cloudy sediment at the bottom of the bottle termed “the mother” – is especially beneficial because of the bacteria and yeast it contains. But there is no research that backs the claim that it offers any health benefits.

One good rule of thumb is that health hacks that promise quick fixes are almost always too good to be true. And even when supplements do offer some health benefits under specific circumstances, it’s important to remember that they are largely exempt from Food and Drug Administration regulations. That means the ingredients on their labels might contain more or less of the ingredients promised or other ingredients not listed, which can potentially cause harms such as liver toxicity.

It’s also important to keep in mind that the global dietary supplements industry is worth more than US$150 billion per year, so companies – and wellness influencers – selling supplements have a financial stake in convincing the public of their value.

Misinformation about nutrition is nothing new, but that doesn’t make it any less confusing.

How nutrition science gets twisted

There’s no doubt that good nutrition is fundamental for your health. Studies consistently show that a balanced diet containing a variety of essential nutrients can help prevent chronic diseases and promote overall well-being.

For instance, minerals such as calcium and iron support bone health and oxygen circulation in the blood, respectively. Proteins are essential for muscle repair and growth, and healthy fats, like those found in avocados and nuts, are vital for brain health.

However, pseudoscientific claims often twist such basic facts to promote the idea that specific diets or supplements can prevent or treat illness. For example, vitamin C is known to play a role in supporting the immune system and can help reduce the duration and severity of colds.

But despite assertions to the contrary, consuming large quantities of vitamin C does not prevent colds. In fact, the body needs only a certain amount of vitamin C to function properly, and any excess is simply excreted.

Companies sometimes claim their supplement is “scientifically proven” to cure illness or boost brain function, with no credible research to back it up.

Some companies overstate the benefits while underplaying the hazards.

For example, wellness influencers have promoted raw milk over pasteurized milk as a more natural and nutritious choice, but consuming it is risky. Unpasteurized milk can contain harmful bacteria that leads to gastrointestinal illness and, in some cases, much more serious and potentially life-threatening diseases such as avian influenza, or bird flu.

Such dietary myths aren’t harmless. Reliance on nutrition alone can lead to neglecting other critical aspects of health, such as regular medical checkups and lifesaving vaccinations.

The lure of dietary myths has led people with cancer to replace proven science-backed treatments, such as chemotherapy or radiation, with unproven and misleading nutrition programs.

How to spot less-than-solid science

Pseudoscience exploits your insecurities and emotions, taking advantage of your desire to live the healthiest life possible.

While the world around you may be uncertain and out of your control, you want to believe that at the very least, you have control over your own health. This is where the wellness industry steps in.

What makes pseudoscientific claims so confusing is that they use just enough scientific jargon to sound believable. Supplements or powders that claim to “boost immunity” often list ingredients such as adaptogens and superfoods. While these words sound real and convincing, they actually don’t mean anything in science. They are terms created by the wellness industry to sell products.

I’ve researched and written about reliable ways to distinguish science facts from false health claims. To stay alert and find credible information, I’d suggest you follow a few key steps.

First, check your emotions – strong emotional reactions, such as fear and anger, can be a red flag.

Next, check that the author has experience or expertise in the field of the topic. If they’re not an expert, they might not know what they are talking about. It’s always a good idea to make sure the source is reputable – ask yourself, would this source be trusted by scientists?

Finally, search for references that back up the information. If very little or nothing else exists in the science world to back up the claims, you may want to put your trust in a different source.

Following these steps will separate the facts from fake news and empower you to make evidence-based decisions.

Aimee Pugh Bernard, Assistant Professor of Immunology and Microbiology, University of Colorado Anschutz Medical Campus

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Sound advice for the majority of us!

The Edwin Hubble Great Debate

The following is more than fascinating; it is an example of how far science has reached; both figuratively and literally.

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One large Milky Way galaxy or many galaxies? 100 years ago, a young Edwin Hubble settled astronomy’s ‘Great Debate’

The Andromeda galaxy helped Edwin Hubble settle a great debate in astronomy. Stocktrek Images via Getty Images

Chris Impey, University of Arizona

A hundred years ago, astronomer Edwin Hubble dramatically expanded the size of the known universe. At a meeting of the American Astronomical Society in January 1925, a paper read by one of his colleagues on his behalf reported that the Andromeda nebula, also called M31, was nearly a million light years away – too remote to be a part of the Milky Way.

Hubble’s work opened the door to the study of the universe beyond our galaxy. In the century since Hubble’s pioneering work, astronomers like me have learned that the universe is vast and contains trillions of galaxies.

Nature of the nebulae

In 1610, astronomer Galileo Galilei used the newly invented telescope to show that the Milky Way was composed of a huge number of faint stars. For the next 300 years, astronomers assumed that the Milky Way was the entire universe.

As astronomers scanned the night sky with larger telescopes, they were intrigued by fuzzy patches of light called nebulae. Toward the end of the 18th century, astronomer William Herschel used star counts to map out the Milky Way. He cataloged a thousand new nebulae and clusters of stars. He believed that the nebulae were objects within the Milky Way.

Charles Messier also produced a catalog of over 100 prominent nebulae in 1781. Messier was interested in comets, so his list was a set of fuzzy objects that might be mistaken for comets. He intended for comet hunters to avoid them since they did not move across the sky.

As more data piled up, 19th century astronomers started to see that the nebulae were a mixed bag. Some were gaseous, star-forming regions, such as the Orion nebula, or M42 – the 42nd object in Messier’s catalog – while others were star clusters such as the Pleiades, or M45.

A third category – nebulae with spiral structure – particularly intrigued astronomers. The Andromeda nebula, M31, was a prominent example. It’s visible to the naked eye from a dark site.

The Andromeda galaxy, then known as the Andromeda nebula, is a bright spot in the sky that intrigued early astronomers.

Astronomers as far back as the mid-18th century had speculated that some nebulae might be remote systems of stars or “island universes,” but there was no data to support this hypothesis. Island universes referred to the idea that there could be enormous stellar systems outside the Milky Way – but astronomers now just call these systems galaxies.

In 1920, astronomers Harlow Shapley and Heber Curtis held a Great Debate. Shapley argued that the spiral nebulae were small and in the Milky Way, while Curtis took a more radical position that they were independent galaxies, extremely large and distant.

At the time, the debate was inconclusive. Astronomers now know that galaxies are isolated systems of stars, much smaller than the space between them.

Hubble makes his mark

Edwin Hubble was young and ambitious. At the of age 30, he arrived at Mount Wilson Observatory in Southern California just in time to use the new Hooker 100-inch telescope, at the time the largest in the world.

A black and white photo of a man looking through the lens of a large telescope.
Edwin Hubble uses the telescope at the Mount Wilson Observatory. Hulton Archives via Getty Images

He began taking photographic plates of the spiral nebulae. These glass plates recorded images of the night sky using a light-sensitive emulsion covering their surface. The telescope’s size let it make images of very faint objects, and its high-quality mirror allowed it to distinguish individual stars in some of the nebulae.

Estimating distances in astronomy is challenging. Think of how hard it is to estimate the distance of someone pointing a flashlight at you on a dark night. Galaxies come in a very wide range of sizes and masses. Measuring a galaxy’s brightness or apparent size is not a good guide to its distance.

Hubble leveraged a discovery made by Henrietta Swan Leavitt 10 years earlier. She worked at the Harvard College Observatory as a “human computer,” laboriously measuring the positions and brightness of thousands of stars on photographic plates.

She was particularly interested in Cepheid variables, which are stars whose brightness pulses regularly, so they get brighter and dimmer with a particular period. She found a relationship between their variation period, or pulse, and their intrinsic brightness or luminosity.

Once you measure a Cepheid’s period, you can calculate its distance from how bright it appears using the inverse square law. The more distant the star is, the fainter it appears.

Hubble worked hard, taking images of spiral nebulae every clear night and looking for the telltale variations of Cepheid variables. By the end of 1924, he had found 12 Cepheids in M31. He calculated M31’s distance as a prodigious 900,000 light years away, though he underestimated its true distance – about 2.5 million light years – by not realizing there were two different types of Cepheid variables.

His measurements marked the end of the Great Debate about the Milky Way’s size and the nature of the nebulae. Hubble wrote about his discovery to Harlow Shapley, who had argued that the Milky Way encompassed the entire universe.

“Here is the letter that destroyed my universe,” Shapley remarked.

Always eager for publicity, Hubble leaked his discovery to The New York Times five weeks before a colleague presented his paper at the astronomers’ annual meeting in Washington, D.C.

An expanding universe of galaxies

But Hubble wasn’t done. His second major discovery also transformed astronomers’ understanding of the universe. As he dispersed the light from dozens of galaxies into a spectrum, which recorded the amount of light at each wavelength, he noticed that the light was always shifted to longer or redder wavelengths.

Light from the galaxy passes through a prism or reflects off a diffraction grating in a telescope, which captures the intensity of light from blue to red.

Astronomers call a shift to longer wavelengths a redshift.

It seemed that these redshifted galaxies were all moving away from the Milky Way.

Hubble’s results suggested the farther away a galaxy was, the faster it was moving away from Earth. Hubble got the lion’s share of the credit for this discovery, but Lowell Observatory astronomer Vesto Slipher, who noticed the same phenomenon but didn’t publish his data, also anticipated that result.

Hubble referred to galaxies having recession velocities, or speeds of moving away from the Earth, but he never figured out that they were moving away from Earth because the universe is getting bigger.

Belgian cosmologist and Catholic priest Georges Lemaitre made that connection by realizing that the theory of general relativity described an expanding universe. He recognized that space expanding in between the galaxies could cause the redshifts, making it seem like they were moving farther away from each other and from Earth.

Lemaitre was the first to argue that the expansion must have begun during the big bang.

The Hubble telescope, which looks like a metal cylinder, floating in space.
Edwin Hubble is the namesake for NASA’s Hubble Space Telescope, which has spent decades observing faraway galaxies. NASA via AP

NASA named its flagship space observatory after Hubble, and it has been used to study galaxies for 35 years. Astronomers routinely observe galaxies that are thousands of times fainter and more distant than galaxies observed in the 1920s. The James Webb Space Telescope has pushed the envelope even farther.

The current record holder is a galaxy a staggering 34 billion light years away, seen just 200 million years after the big bang, when the universe was 20 times smaller than it is now. Edwin Hubble would be amazed to see such progress.

Chris Impey, University Distinguished Professor of Astronomy, University of Arizona

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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So wonderful that in this modern era we can read articles from distinguished scientists in the comfort of our own homes.