Friday, July 3, 2026
The Science of Loneliness
Loneliness has been described as a public health crisis, compared to
smoking in its effects on lifespan, and declared an epidemic by health
ministers in multiple countries. But until recently, science could say little
about what loneliness actually is inside the brain: what neurons fire, what
circuits activate, what the biological difference is between being alone and
feeling alone. A wave of new research is beginning to change that.
The neurons that register isolation
In 2025, Harvard neuroscientist Catherine Dulac published a study that may
be the most precise look yet at what loneliness does to the brain at the
cellular level. Her team at the Howard Hughes Medical Institute isolated female
mice for five days, with brief social reunions on alternating days, and used
genetic tools to map exactly which neurons became active during isolation and
which ones fired during reunion.
They found two distinct clusters in the hypothalamus, a brain region
involved in regulating hunger, thirst, and other survival drives. One cluster
activated during isolation and produced an aversive, hunger-like state: an
internal craving for company. A second cluster activated during reunion and
connected to the brain’s dopamine reward system, producing something that felt
like relief or satisfaction. The two circuits worked in opposition, like the
push and pull of appetite and satiation.
“Loneliness is not a mood. It is a
drive, like hunger,” Dulac said. “It has a specific neural substrate, and when
that drive is satisfied, the brain registers it as a reward.”
Touch as the
only resolution
One of the most striking findings from Dulac’s experiments was what did and
did not resolve the isolation signal. When mice were separated from each other
but could still see, smell, and hear their companions through a transparent
barrier, the loneliness neurons kept firing as if full isolation were in
effect. Only physical contact, specifically tactile interaction with another
mouse, quieted the circuit. The researchers compared this to being able to see
food through glass: awareness of the thing you need is not the same as having
it.
This may help explain why social media use, which provides visual and
textual contact but not physical presence, so often fails to relieve loneliness
and in some studies appears to worsen it. If the loneliness circuit evolved to
respond to physical co-presence, digital proximity may not speak the same
language.
Loneliness as a survival signal
Parallel work from Kay Tye’s lab at the Salk Institute and MIT has
identified loneliness-related circuits in the dorsal raphe nucleus, a brainstem
region involved in social motivation. Tye’s team found that isolating mice
caused a specific population of dopamine neurons to become hyperactive, priming
the animal to seek social contact urgently. When these neurons were
artificially activated in grouped mice, the mice behaved as if they had been
isolated, seeking out company even when company was already present.
Together, the Dulac and Tye findings point toward a view of loneliness not
as an emotional failure or a personality trait, but as a biological alarm
system. Social species need each other to survive. A brain that registers
isolation as aversive and social contact as rewarding has a selective advantage
over a brain that does not. Loneliness, on this view, is evolution’s way of
keeping social animals social.
What chronic loneliness does to the body
The biological effects of prolonged loneliness are well documented and
extend far beyond mood. Chronic loneliness is associated with elevated cortisol
and inflammatory markers, disrupted sleep architecture, impaired immune
function, and increased risk of cardiovascular disease. A widely cited analysis
by Julianne Holt-Lunstad found that social isolation increases mortality risk
by roughly 26%, comparable to smoking 15 cigarettes a day.
The new cellular research offers a possible mechanism: a loneliness drive
that never gets satisfied keeps the stress-related circuits in the hypothalamus
chronically activated. The same system that evolved to push animals toward
social contact in the short term becomes damaging when the craving goes unmet
for weeks or months or years.
The hardest question
What the neuroscience cannot yet answer is why some people feel lonely in a
crowd and others feel fine in extended solitude. Individual differences in the
sensitivity of these circuits, shaped by genetics, early experience, and
learned patterns of relating, probably account for much of that variation.
Dulac’s lab is now looking at how early social deprivation changes the
development of loneliness circuits in ways that may persist into adulthood.
What the research does establish, with increasing clarity, is that
loneliness is not a character flaw or a sign of weakness. It is what a working
brain feels when one of its core biological needs goes unmet. That reframing
may matter less for the science than for how we treat the people around us who
are quietly running on empty.
Source
·
Dulac, C., et al. (2025).
Hypothalamic circuits mediating the aversive state of social isolation. Howard Hughes Medical Institute / Harvard University.
·
Tye, K.M., et al. (2018). Social
reward and loneliness circuits in the dorsal raphe nucleus. Cell.
·
Holt-Lunstad, J., et al. (2015).
Loneliness and social isolation as risk factors for mortality. Perspectives on Psychological Science.
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Thursday, July 2, 2026
NASA’s Webb Pinpoints Millions of Stars Within Cigar Galaxy - UNIVERSE
Located 12 million light-years away and undergoing rapid star formation,
edge-on spiral galaxy Messier 82 (M82) is a scientifically unique sight to
behold, and now NASA’s James Webb Space Telescope has revealed previously
unseen details.
M82’s intense star formation,
thought to be the result of a galaxy merger, will be a short-lived event in
astronomical terms, estimated to last a few hundred million years in its
entirety. This temporary phase of extreme star formation relative to the galaxy’s
mass, as well as its location in the local universe, are among the factors that
make M82, also known as the Cigar galaxy, a one-of-a-kind environment to study.
Image: M82 Cigar Galaxy (Webb + Hubble)
Scientists used NASA’s James Webb Space Telescope to
image edge-on starburst galaxy Messier 82 and trace its evolutionary history.
This Webb and Hubble composite image includes 16.5 million stars (blue-white),
dust grains (red-orange), and ionized hydrogen gas (yellow).
Image: NASA, ESA, CSA, Adam Smercina (STScI, Tufts),
Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan
(STScI)
A team of astronomers recently
completed an imaging survey with the Webb telescope. This program entailed a total of 65 hours of observation time
with Webb’s NIRCam
(Near-Infrared Camera) instrument and revealed never-seen-before details of the starburst galaxy, including its distended disk structure and millions
of individual stars. Webb’s high-resolution imaging, specifically of the main
plane of the galactic disk, has unlocked vital information for astronomers as
they seek to uncover M82’s formation history. Additionally, the Webb data will
help scientists understand the current processes occurring within the starburst
galaxy.
“M82 is a mess, but it’s a
beautiful mess. We don’t fully understand what’s going on, especially
concerning its evolutionary history. What could have triggered such an elevated
rate of star formation? How long has this galaxy been driving plumes of material
away from its center?” said principal investigator Adam Smercina, a NASA Hubble
Fellow at the Space Telescope Science Institute in Baltimore, and incoming
Assistant Professor at Tufts University in Massachusetts. “M82 is an ideal
galaxy evolution laboratory because it has properties that allow us to probe
important physical processes, such as how stars form in such environments and
how that activity drives outflows. M82 provides a simultaneous window onto many
astrophysical questions, in a way that no other galaxy in the local universe
can.”
Image: M82 Cigar Galaxy (NIRCam
Image)
NASA’s James Webb Space Telescope observed edge-on
starburst galaxy Messier 82, peering through dust to reveal 16.5 million stars
and the galaxy’s distended disk structure. Scientists seek to learn the
galaxy’s evolutionary history with the Webb data.
Image: NASA, ESA, CSA, Adam Smercina (STScI, Tufts),
Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan
(STScI)
Prior to Webb, many observatories
looked at the starburst galaxy, including NASA’s Hubble and retired Spitzer space telescopes. However, the sheer volume of
dust within that galaxy limited the amount of information astronomers could
acquire on M82 at high resolution. While Webb has previously looked at this galaxy, the duration of the new imaging survey, combined
with the telescope’s infrared sensitivity, enabled it to pierce through the
thick dust.
Image: M82 Cigar Galaxy
(Hubble/Webb Side-by-Side)
Side-by-side comparison of a portion of starburst
galaxy Messier 82 (M82) as seen by NASA’s Hubble (left) and James Webb (right)
space telescopes. Hubble detailed M82’s gas and dust structure, while Webb
pierced through the dust and resolved millions of stars in infrared light.
Image: NASA, ESA, CSA, Adam Smercina (STScI, Tufts),
Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan
(STScI)
The telescope’s near-infrared-light
view is a snapshot of a scene that has been evolving over a couple hundred
million years. Webb’s image contains approximately 16.5 million individual
stars dispersed throughout the galaxy. The light from these stellar sources is
depicted as luminous blue granules. This is only a small portion of the total
amount of stars astronomers think reside in a galaxy like M82, with the
majority too faint to be seen.
“The sheer number of stars that we
were able to resolve with Webb is incredible,” said team member Benjamin
Williams of the University of Washington. “It’s a whole different world from
what we’ve been able to see with other telescopes. All of these stars
collectively provide a detailed fossil record of the formation and evolution of
M82.”
Moving inward, the increase in
brightness and the asymmetrical shape of the galactic disk hints at the spiral
galaxy’s unique underlying structure. The differing radii between the two sides
suggests that M82 has a distorted shape, which can happen during intense galaxy
mergers.
“At first glance, the disk of the
galaxy may seem less spectacular because Webb sees through the dust,” said team
member Eric Bell of the University of Michigan. “But M82 is a delightfully
complex system. Webb’s observations will help us address some ongoing
mysteries, such as how star formation has moved within M82 over the last few
billion years.”
Video: M82
Cigar Galaxy (Webb + Hubble Fade)
NASA’s James Webb Space Telescope’s near-infrared
observation of M82 is the most recent addition to overall data on this
starburst galaxy. The Hubble Space Telescope is one observatory that has
previously looked at M82, detailing the gas and dust structure seen in visible
light.
Video: NASA, ESA, CSA, STScI,
Alyssa Pagan (STScI)
Because of the extreme star formation
within the galaxy, which is 10 times faster than the Milky Way galaxy’s star
formation rate, stellar birth will eventually be disrupted. M82’s stellar
frenzy is causing bipolar plumes of material to be ejected above and below the
disk. Though it looks like a tumultuous region, the hourglass-shaped outflows
appear to have a layered structure. The yellow tendrils of material closest to
the galaxy’s disk represent ionized gas, whereas the orange material farther
away depicts small dust grains. These grains are called polycyclic aromatic
hydrocarbons and are helpful in tracing material in the space between the
galaxy’s stars, also known as the interstellar medium.
The information collected as part of
this Webb study is just one dataset scientists will analyze as they seek to
piece together this starburst galaxy’s formation history.
“Galaxies are such intricate ecosystems
that if you truly want to understand them, you have to pull datasets from
different missions together,” said team member Kristen McQuinn of the Space
Telescope Science Institute. “One mission cannot fully answer all of the
questions we have about M82. Combining the data collected by different
telescopes, like Webb and Hubble, is powerful. When you marry the datasets, you
expand what you can probe, and the questions that you can pose are even more
complex.”
The James Webb Space Telescope is the
world’s premier space science observatory. Webb is solving mysteries in our
solar system, looking beyond to distant worlds around other stars, and probing
the mysterious structures and origins of our universe and our place in it. Webb
is an international program led by NASA with its partners, ESA (European Space
Agency) and CSA (Canadian Space Agency).
To learn more about Webb, visit: https://science.nasa.gov/webb
Source: NASA’s Webb Pinpoints Millions of Stars Within Cigar Galaxy - NASA ScienceA thermodynamic approach to gravity could explain cosmic acceleration without dark energy - Physics - General Physics - Quantum Physics
A
small causal diamond used as a tiny local laboratory for deriving gravity from
thermal physics. Heat flows in and out across the light-like boundaries of the
diamond, allowing the authors to ask what kind of gravitational theory emerges
from a more general thermodynamic process that might happen inside the diamond.
Credit: Isichei and Magueijo / Physical Review Letters.
Gravity,
the force that attracts objects toward each other, is currently framed by
Albert Einstein's theory of general relativity. This framework describes
gravity as the curvature of spacetime, the invisible four-dimensional fabric of
the universe.
While general relativity is now the
central theory of gravity, it fails to explain some cosmological phenomena and
mysteries, such as the so-called cosmological constant problem. This is the
unexplained mismatch between the observed energy of empty space and the far
greater values predicted by quantum theories.
In a recent
paper published in Physical Review
Letters,
researchers at Imperial College London tried to frame gravity using
thermodynamics, the framework that describes how energy and heat transform.
Their study builds on a seminal
paper by theoretical physicist Ted Jacobson, published more than three decades ago.
"I first came across Jacobson's
seminal 1995 work when I was just out of my Ph.D., and I found the idea
fascinating," João Magueijo, senior author of the paper, told Phys.org.
"He inverted the logic of Hawking and Bekenstein's arguments that Einstein gravity has temperature and entropy and instead used thermal physics to derive Einstein gravity. I wanted to do something with this idea for years, but all my attempts failed miserably. Then last year, while on holiday on a remote Greek island, part of which has no internet, which may have helped, I realized that most previous work had tried to retrofit existing theories of gravity into Jacobson's construction."
The
thermodynamic cycle proposed in the Letter. Standard Einstein gravity
corresponds to the degenerate case in which only heat-flow legs are present.
Allowing the additional work-producing legs opens the door to new gravitational
theories, including ones in which matter-energy conservation is modified.
Credit: Isichei and Magueijo / Physical Review Letters.
Building on this realization,
Magueijo started exploring the possibility of describing gravity starting from
thermal physics alone, without trying to determine what type of gravity theory
would emerge. His hope was that this process would lead to entirely new
theories of gravity that no one had thought of before.
Linking gravity, thermodynamics and the expanding universe
To further develop the ideas he had
been contemplating, Magueijo started collaborating with Ray Isichei, a Ph.D.
student he was supervising at Imperial College. Together, the two researchers
started examining gravity from a thermodynamic standpoint, specifically framing
it as an Otto cycle, a thermodynamic construct that describes how gasoline
engines work.
"We asked what happens if the
thermodynamic process behind gravity is not just heat flow," Magueijo
explained. "In ordinary thermodynamics, heat is almost never the whole
story: There may also be chemical reactions, expansion against a piston, work
being done or other contributions. So, we added this missing 'something else'
to the argument, without prejudice regarding what would come out the other
side."
To their surprise, the researchers
found that the gravitational theory they derived allowed matter and energy to
be created or destroyed. This was a total shock, as the conservation of energy
and matter is a fundamental physical principle. The fact that it could be
violated almost prompted them to abandon their theory altogether.
"The idea did not end up in
the garbage bin because we realized that, when applied to the universe as a
whole, it could reproduce the observed acceleration of cosmic expansion without
having to posit dark energy, a cosmological constant, or any of the usual
ingredients invoked to explain it," Magueijo said.
"Normal matter should pull
back and decelerate the expansion of the universe, but that assumes the usual
conservation laws. In this model, normal matter whose conservation law is
modified (allowing for continuous creation) can instead drive acceleration."
Fueling new theoretical studies
The team's study offers a fresh and
unconventional theory of gravity, suggesting that Einstein's theory of
relativity could also potentially be framed as a thermodynamic process. This
theoretical framework could eliminate the need for a conventional cosmological
constant, potentially helping to tackle a long-standing issue in cosmology.
While the new theory devised by
Magueijo and Isichei is intriguing, it is still speculative and in its early
stages. The researchers are now planning further studies aimed at developing it
further and comparing its predictions with available cosmological evidence and
experimental results.
"A lot of work now needs to be done comparing the model in detail with cosmological observations," Magueijo added. "When I started my Ph.D., back in 1990, you could still say almost anything in cosmology, because the paucity of data allowed it. Cosmology has since become a high-precision, data-driven subject. Any new idea now must pass the gauntlet of observation."
Source: A thermodynamic approach to gravity could explain cosmic acceleration without dark energy
NASA Seeks Volunteers for New Yearlong Simulated Moon, Mars Mission
A research volunteer uses augmented reality goggles to
perform astronaut-like tasks during a simulated space mission. Participants
selected for NASA’s first Moon and Mars Exploration Analog mission also will
perform tasks in immersive, interactive environments while living inside
habitats that simulate traveling to and living on the Moon and Mars.
Credit: NASA
NASA is recruiting research participants
for the agency’s next simulated deep space mission. Beginning no earlier than
August 2027, research volunteers will spend one year living and working in
interplanetary environments at the agency’s Johnson Space Center in Houston,
operating under isolated conditions expected during crewed missions to the Moon
or Red Planet.
Insights from this new, yearlong experience, called the Moon and Mars
Exploration Analog, can be used to help keep astronauts safe and mission-ready
during future planetary surface operations. The results also could inform plans
for a sustained lunar presence through the agency’s Moon
Base and future Artemis missions.
NASA is looking for applicants for the approximately year-long mission
simulation, which will take place in two confined habitats. In addition to
specific physical and education requirements, volunteers must be willing to
take part in a multi-day selection process and pass NASA’s physical and
psychological assessments, found on the Moon and Mars Exploration Analog web page. Candidates also should have a strong desire for unique, rewarding
experiences, and interest in contributing to NASA’s work to prepare for
extended stays on the lunar surface and the first crewed mission to Mars.
The Moon and Mars Exploration Analog evolves elements of the agency’s HERA (Human Exploration Research Analog)
and CHAPEA (Crew Health And Performance Exploration Analog) missions into a single, integrated mission to streamline how
researchers evaluate astronaut adaptation across the full range of potential
mission scenarios. Using the HERA habitat as a spacecraft and the CHAPEA
habitat as a base, the volunteers will live and work in confined, isolated
environments that simulate months-long flights to and from other planetary
surfaces. They also will mimic surface operations, including mock Mars walks
and using a rover to travel to exploration sites located beyond the main
habitat.
Throughout the Moon and Mars Exploration Analog mission, researchers will study
crew health and performance under resource limitations and mission demands.
These missions also help NASA assess and validate hardware, technologies,
protocols, requirements, and other systems designed to support crew health and
performance on long-duration deep space missions, all without leaving Earth.
The effort will provide valuable data for NASA’s Human
Research Program, which innovates ways to keep
astronauts healthy and mission-ready.
To apply, visit: NASA Analogs Recruiting
As part of the Golden Age of innovation
and exploration, NASA will send astronauts on increasingly difficult missions
to explore more of the Moon for scientific discovery, economic benefits,
establish an enduring human presence on the lunar surface, and to build on
the foundation for the first crewed missions to Mars.
For more about NASA’s Human Research Program, visit: https://www.nasa.gov/hrp/
Source: NASA Seeks Volunteers for New Yearlong Simulated Moon, Mars Mission - NASA
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