Hello. I'm Matin Durrani, and welcome to a
very special edition of the Physics World weekly
podcast,
where we're going to be revealing the top
10 breakthroughs in physics for 2025.
Every year here at Physics World, we pick
what we think have been the biggest breakthroughs
over the last twelve months, and we've had
chosen some amazing successes over the years that
include the Higgs boson,
gravitational waves, and the shadow around a black
hole. With last year, the top prize going
to work on quantum error correction at Google
and elsewhere.
So taking you through our choices for 2025,
I'm joined by my colleagues Margaret Harris,
Tammy Freeman, Michael Banks, and Hamish Johnson.
The physics world breakthrough the year 2025
is sponsored by Reports on Progress in Physics.
Celebrating the most significant advances across the physical
sciences,
this award highlights discoveries that reshape our understanding
of the universe and inspire future innovation.
Reports on Progress in Physics is the leading
journal for authoritative
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connecting researchers worldwide with cutting edge insights across
every field of physics.
From quantum technologies to astrophysics,
it provides the depth and clarity that drive
scientific progress.
Search reports on progress in physics on your
favorite browser to explore the ideas transforming science
today.
So let's get cracking on the top 10
physics world breakthroughs in physics for 2025,
which, just to remind you, we pick based
on three
criteria. So in addition to having been reported
in physics world in 2025,
our selections have to represent a significant advance
in knowledge or understanding,
be important for scientific progress and or development
of real world applications,
and be of general interest to Physics World
readers.
So we're gonna start with a bit of
astronomy, with astronomers creating what they say is
a weather map
for a gas giant exoplanet.
Now it's hard enough for trying to predict
the weather here in on Earth, although I
know it's been a pretty dry year in
Bristol in the Southwest corner of England where
we are. So this sounds pretty cool to
me. Hamish, you're gonna explain this breakthrough for
us.
That's right, Matin. This this first, breakthrough is
astronomy related breakthrough, and it has to do
with exoplanets.
Now it's only been thirty years since the
first exoplanet,
orbiting a star, that's a planet orbiting a
star other than the sun, was discovered.
And today, astronomers know of more than 6,000
such objects.
And this breakthrough, it's been made by Lisa
Nortman
at Germany's
University
of Gottingen
and colleagues,
and they've used the European
Southern Observatory's
Very Large Telescope
to create what they're saying
is the first weather map of an exoplanet.
Now this exoplanet is a hot Jupiter.
It's a gas giant called WASP
one twenty seven b,
and it orbits very near to its star.
So this is not something that we have
in a in in the solar system. It's
a very sort of exotic
thing as far as we we're concerned. And
what Nortman and colleagues did is they studied
the absorption
spectrum of starlight that had passed through the
exoplanet's
atmosphere.
And
by, looking at the Doppler shift of this,
transmission spectrum,
they could deduce that the winds on WASP
one twenty seven b can reach as as
high as 33,000
kilometers per hour,
which is pretty fast. That's quick. It it
it is. Yeah. Yeah. And and what's more,
by looking at the, sort of, the distribution
of of how,
the light is Doppler shifted,
they could create a rough weather map of
the exoplanet. Now, it's important to say that
they weren't actually able to look at different
points
on the exoplanet
and say the weather is like this there.
What they did is they they looked at
this distribution
and somehow used that information to
infer what the weather was like from the
pole down to the Equator
and, back again to to the other pole.
So they were able to conclude,
along with looking at the winds, they were
able to conclude
that the exoplanet's poles are cooler
than the rest of the exoplanet,
where,
temperatures can exceed,
over a thousand degrees Celsius. So, again, a
very strange place.
Imagine Jupiter, but it's a thousand degrees Celsius,
sort of a weird world.
And they also, detected water vapor in the
atmosphere,
and that raises the possibility of very exotic
forms of rain on the planet.
So rain,
other than
how we know it, I suppose.
And, you know, I think we picked this
one. Really, there's lots of really fantastic exoplanet
research out there, thousands that have been discovered.
But this was
a a a really interesting,
example of how we can we can now
actually see the atmosphere
of these exoplanets
using, you know, the very latest telescopes.
So very hot, very windy, and exotic rain.
I don't think I wanna live there. Thanks,
Hamish. Now from exoplanets out in space down
to our planet here on Earth, our next
breakthrough through of the year is a fascinating
study
about using the phones we all carry around
with us to create an early warning system
for earthquakes
or at least using Android phones. Michael, can
you tell us about this breakthrough, which seems
like a great example of citizen science? Yeah.
So this is all about using mobile phones
to detect earthquakes. So traditional
earthquake early warning systems usually use networks of
seismic sensors
that rapidly detect earthquakes in areas close to
the epicenter.
They also issue warnings to, people also across
the affected region.
Yet the issue is that building such networks
of bulky sensors, it's expensive,
you know, and this means that many earthquake
prone regions do not have them. So to
get around this problem, researchers in The US
utilized the accelerometer housed in millions of mobile
phones worldwide
to create an app based Android earthquake alert
system.
So testing the app between 2021 and 2024
led to the detection of an average of
312
earthquakes a month with magnitudes ranging from 1.9
to 7.8 on the Richter scale.
But what is more, the app could also
alert people in the area. So for earthquakes
of magnitude 4.5
or higher,
the system sent so called take action alerts
to users.
It also delivered lesser be aware alerts to
regions expected to experience a shaking intensity of
three or four.
So the team now aimed to build on
this earthquake early warning system based on Android
mobile phones by producing maps of ground shaking
as well.
And this could all help assist the emergency
response services when an earthquake occurs.
Thanks, Michael. So from communicating with mobiles to
communicating via the cables that make up the
Internet,
which is the almost invisible technology that underpins
modern life. Now it seems the researchers have
developed a new kind of fiber that loses
that lose less data
as the signals get sent down them. Tammy,
what's this one about?
So optical fibers form the backbone of the
Internet carrying light signals across the globe.
But sunlight is always lost as it travels
through the fiber, which means that these signals
must be amplified every few dozen kilometers.
Now amazingly, the performance of even the best
fibers has remained largely unchanged for nearly four
decades
until now.
Physicists at the University of Southampton
have developed a new type of fiber that
exhibits 35%
less attenuation
while transmitting signals faster than standard glass fibers,
and they achieved this by replacing the glass
core of a conventional fiber with air.
To guide the light through this hollow core,
it's surrounded by a microstructure
of ultrathin glass membranes that reflect certain frequencies
to trap the light and keep it moving
through the fiber.
So to test this design, the team, which
also included researchers from Microsoft Azure Fiber,
they measured the transmission through a full spool
of fiber, then they cut it into shorter
lengths and compared the results.
And they found that their hollow fibers reduced
the attenuation
to just naught point naught nine one decibels
per kilometer at fifteen fifty nanometers, which is
a wavelength used for telecoms.
And this means that long cables would need
fewer amplifiers,
lowering the costs and the energy use.
The new hollow fiber also supports a higher
bandwidth
than a normal fiber,
which means that a single strand can carry
far more channels at once.
And because the speed of light's faster in
air than in glass, the data could travel
the same distance up to 45%
faster.
Now Microsoft has begun testing the new fibers
in real systems,
installing segments in its network and sending live
traffic through them.
And these trials prove that the hollow core
design works with existing telecoms equipment and opens
the door to a gradual rollout of this
new source of fiber.
And as team leader Francesco Paletti suggests, one
day, they could even replace existing undersea cables.
So that's the first three of our physics
world breakthroughs of the year for 2025
done.
Now next up is some cool condensed matter
physics that's involved superfluidity
spotted in molecular hydrogen for the first time.
Now, Margaret, physicists are pretty familiar with superfluidity
in helium three and helium four
atoms, but now we're talking about molecules, aren't
we?
Yeah. We're talking about specifically about molecular hydrogen,
which is the simplest and lightest of all
molecules. You take one hydrogen atom, you take
another hydrogen atom, you link them together.
And theorists predicted that this molecular hydrogen would
enter a superfluid state at a temperature between
one to two Kelvin above absolute zero,
which is pretty cold.
But the real problem with that is that
molecular hydrogen freezes at 13.8
Kelvin, So, obviously, it's not going to be
behaving like a superfluid if it's further than
solid.
So before they could verify this prediction, Takamasa
Momosa and colleagues at the University of British
Columbia in Canada,
they first had to develop a way to
keep the hydrogen in a liquid state.
And they did that by confining clusters of
hydrogen molecules inside nanodroplets of helium and supercooling
them to below their freezing point, which,
I mean, I've never done it, but I
imagine that isn't exactly easy. Certainly, it sounds
like an impressive feat.
And then once they've done that, they faced
a further barrier, which was figure out how
to detect whether the hydrogen was superfluid or
not.
And to do that, they stuck a methane
molecule in with the cluster of hydrogen molecules
and watched it rotate.
And when it started to rotate without friction,
they knew they'd seen superfluidity.
Apparently, it took them nearly twenty years to
sort of develop this experiment at this point,
so this breakthrough was a long time coming.
And it's a testament to the dedication and
ingenuity of the team that they were able
to do it at all. This is a
real physicist experiment on my view at least.
They now plan to study larger clusters of
hydrogen with the aim of exploring the boundary
between classical and quantum behavior in this system.
So, I mean, they've seen superfluidity with 10
hydrogen molecules. Great.
Can I see it with a 100? What
about a thousand or a million? We don't
know the answer, but it'll be really exciting
to find out. Like you say, Margaret, definitely
one for the fit the hardcore physicist, I
think, especially something that's taken twenty years to
get through.
So amazing achievement, that one. And speaking of
molecules, research have found some pretty interesting molecules
on the asteroid Bennu, which has caught our
eye, hasn't it, Margaret? What have they found?
Well, Matin, it's almost a case of asking
what haven't they found on Bennu.
I mean, they might be looking for not
finding Jimmy Hoffa or Bigfoot, but they found
almost everything else. So back in February, we
reported that two teams had found salt and
certain amino acids in samples of the asteroid
Bennu,
which NASA's OSIRIS REx spacecraft visited back in
2020.
These samples got parachuted back to Earth in
2023, and ever since then, various groups of
scientists have been studying them, hoping to answer
questions about what was around in the earliest
solar system, chemically speaking, and how it led
to the kinds of stuff we see around
us today.
Now finding salt and amino acids on an
asteroid is interesting because they're both important for
living organisms.
Lots of animals, including us, need salt to
survive,
and amino acids are the building blocks of
the DNA and RNA that provide the instructions
for making life.
So finding these fairly complex molecules on an
asteroid is a pretty big deal.
Then just a few days ago, we got
some new results about Bennu's composition showing that
the asteroid also contains traces of glucose and
ribose, which are both essential sugars,
plus a bunch of different nitrogen and oxygen
containing organic compounds plus supernova
dust. And this is all really adding to
this idea that asteroids could have delivered some
of the, quote, ingredients for life to the
early Earth
while it was still essentially a smoldering ball
of empty rock,
and thereby kick starting the process that led
to the evolution of life.
This is a hypothesis that's been kicking around
for decades, but thanks to our OSIRIS REx
and other sample return missions, we're finally getting
some answers about how plausible it really is.
However, if I could add just a little
down note here, several of the scientists involved
in this particular breakthrough are or were affiliated
with NASA, which is the US National Air
and Space Administration.
NASA's facing massive budget cuts and layoff due
to the anti science attitude of the current
US government,
and NASA's Goddard Space Flight Center in particular
is looking at significant reductions in staffing.
It's perhaps indicative of the situation that at
least one of the scientists who led this
research is in this breakthrough
and was employed at NASA Goddard at the
beginning of 02/2025
is no longer there.
So we like to celebrate breakthroughs, but this
is kind of the reverse. It's a breakdown
of the year in terms of our ability
to discover things like this because if it
continues, then we're gonna lose the people and
skills we need to make these discoveries happen.
In fact, we already are losing them, and
we'd be remiss not to mention that somewhere
in this podcast.
Yeah. Very good point, Margaret. Breakdown of the
year. Yeah. That's something we didn't want hope
we wouldn't think think would have happened. But,
very good point. But, you know, sending asteroid
samples back to Earth and studying them, I
mean, how cool is that for getting people
into physics and astronomy and science and getting
them excited? It's the kind of thing, especially
younger people will be, you know, fascinated about.
Yeah. If we only keep if we can
only keep them there, it'd be fantastic. Yeah.
So we're now halfway through our list of,
the top 10 breakthroughs of the year for
2025 in physics. We're gonna switch gear and
move over to medical physics.
And, Tammy, we've gone for some new work
using what's known as proton
arc therapy,
which involves using protons to treat patients with
cancer, but in a better manner than has
been possible before.
Yes. So this study is about proton therapy,
a cancer treatment in which beams of protons
are precisely directed onto a tumor to destroy
targeted cells.
Now currently, proton therapy is mostly performed using
a technique called pencil beam scanning, in which
a narrow beam of protons is scanned over
the target to match the tumor shape
with different beam energies used to build up
depth layers and effectively paint the dose onto
the tumor volume.
Now this this approach provides highly conformal dose
distributions,
which means that the proton dose matches really
well with the shape of the tumor.
But it can be limited by the small
number of beam directions that it can deliver
in an acceptable treatment time.
Now a team at the Trento Proton Therapy
Center in Italy is working on a new
type of treatment delivery
called proton arc therapy.
Here, the proton beams are irradiated onto the
target at a large number of beam angles
while the gantry moves in an arc trajectory
around the patient.
And during this rotation,
the beam energy and intensity are adjusted
to map the required dose onto the target
volume.
Now working with researchers at research laboratories in
Sweden,
the team compared proton arc therapy plans with
state of the art pencil beam scanning plans
for 10 patients with head and neck cancers.
And they found that proton arc therapy improved
the dose conformality compared with the pencil beam
plans. So it did it delivered equivalent dose
to the tumor target, but less dose to
the nearby organs at risk, with the largest
impact seen in reducing dose to the brain
stem.
And the team also ran a feasibility test
that confirmed that it's actually possible to deliver
this proton arc therapy in the clinic.
The big breakthrough here is that following these
initial tests, the researchers then performed the world's
first clinical treatments using proton arc therapy.
At the time of writing their paper, they
treated nine cancer patients,
five with head and neck tumors, three with
brain tumors, and one with thoracic cancer.
Now importantly, all of these treatments were performed
using the medical center's existing proton therapy system
and using the same clinical workflow.
Looking ahead, the researchers aim to use this
protonark therapy to treat tumors in other regions
of the body.
So a technique that potentially could really be
of great benefit to, to people,
with cancer. That sounds great,
and really promising work. And over in biophysics,
Tammy, if I can stick with you, this
year, we reported on some really interesting work
using a quantum bit
that was formed from a fluorescent protein
that could be used as a sensor that
can be directly produced inside living cells. Now
to me, this sounds really fascinating. It's quantum
physics and biophysics
and a new kind of sensor. So do
you wanna tell us about this one? Sure.
So this breakthrough is from researchers at the
University of Chicago, Pritzker School of Molecular Engineering.
And they designed a protein quantum bit or
qubit
that can be produced inside living cells.
And this protein qubit can be used as
a quantum sensor that can detect tiny changes
in magnetic fields.
So many of today's quantum sensors are based
on nitrogen vacancy or NV
sensors in diamond.
And when excited with laser pulses, these crystal
defects emit a fluorescent signal that can be
used to monitor slight changes in the magnetic
properties of a nearby sample.
For biological applications, however, these sensors are relatively
large, and they're difficult to precisely position inside
living cells.
So instead, the team, led by Peter Maurer
and David Avshalom,
took a biological system and turned it into
a qubit.
They used fluorescent proteins that are just three
nanometers in diameter
and can be genetically encoded
such that they're produced by cells at a
desired location with atomic precision.
What's special about these proteins is that they
possess similar optical and spin properties
to those of NV center based qubits,
in that they have a metastable
triplet state.
So to demonstrate that their idea worked, the
researchers created an optically addressable spin qubit in
a yellow fluorescent protein,
and they used a near infrared laser pulse
to read out its triplet state with up
to 20% spin contrast.
Next, they genetically modified the protein so that
it was expressed in bacterial cells, and they
measured signals in this case with a, contrast
of up to 8%.
So while this performance
doesn't match that of the NV quantum sensors,
These fluorescent proteins could enable magnetic resonance measurements
directly inside living cells, which NV centers simply
cannot do.
And because of this, Maurer suggests that the
new protein qubits
could transform medical and biochemical
studies
by probing protein folding, monitoring redox states, or
detecting drug binding at the molecular scale.
So thanks, Tammy. That's some fascinating, biophysics and
quantum physics. And we're down to the final
three picks for the breakthrough of the year
in physics for 2025.
Hamish, I'm gonna come back to you now
for some imaging and condensed matter physicists,
with physicists saying that they've recorded the highest
ever resolution
images of a single atom.
Well, we do like breaking records here at
Physics World. So, do you wanna tell us
about this one? And can you pronounce the
technique?
It's got a funny name. Well, we'll see.
Yeah. So,
yes, this this is a a breakthrough in
terms of,
resolution with an electron micros-
with an electron microscope. But there's much much
more to it, which is why we selected
it. This is related to twisted
materials, this idea of twistronics.
When you take two
atomic,
atomically
thin
lattice layers and twist them with respect to
each other, and you can get some really
strange,
properties in these, twisted systems.
The result is something called a moire superlattice
of atoms. And you can by
adjusting the twist angle,
you can adjust this superlattice, the distance between
the atoms,
and then you can also adjust the electronic
properties of the system,
which researchers have found to be very useful.
And in this, study,
Yichao Zhang at the University of Maryland
and Pinshain Huang
of the University of Illinois
at Urbana
Champaign,
have used a technique called
electron tachygraphy
to capture the highest resolution
images ever
of atoms,
and they've done so in a moire
superlattice
made of tungsten
diselenide.
Now,
electron ticography,
it's an electron microscopy
technique
that uses diffraction
to boost the resolution of electron microscopy. Now,
electron microscopy has got pretty high resolution already,
and you can see individual atoms with, some
electron microscopes.
But diffraction is used to to improve this.
And they were able to look
at this moire superlattice
at a resolution
of 15
picometers.
And that's pretty good when you consider that
the size
of an atom. Okay, what's the size of
an atom? It's a bit wooly, the definition.
But typically, you know, it's defined to be
about a 100
picometres,
a 150 picometres, so they're you know, the
resolution is much much smaller
than the actual size of the atoms
that they're looking at.
And I suppose
a a very interesting thing,
that they used this technique to do
is they looked at collective lattice vibrations
called moire phasons.
And so these are a bit like, the
familiar phonons,
collective
sound waves that occur in normal lattices.
But they occur in these moire superlattices,
and they're actually much lower energy and much
weaker,
but they do have,
a very important effect on the electronic properties
of these twisted materials.
And so,
by using this technique to observe these phasons,
physicists,
have the chance to really understand why
these twisted materials have these really strange and
exotic
electronic properties. Because often these electronic properties arise
because of interactions between the electrons and the
lattice vibrations,
you know, the classic example being superconductivity.
So,
yeah, a very a very high resolution
elect,
electron microscopy technique
that opens up a new field, a new
way of studying,
these materials. So, yep, very exciting, and that's
why it's in our top 10. Brilliant stuff,
Hamish. Thanks very much. And if I can
stick with you, now we always do know
that particle physics gets, people very excited. And
our penultimate pick for this year is some
work done at CERN,
where researchers at the base experiments have measured
the magnetic properties of antimatter with record breaking
precision.
Tell us about this one, Hamish. Well, this
is I mean, this has to do with
one of the biggest mysteries
of physics.
And that mystery is why is there much
more matter
than antimatter in the visible universe? The the
standard model says
that,
when the universe began in the big bang,
there would have been roughly equal amounts of
matter and antimatter.
But when we look around us well, you
know, look around the room that you're in,
it's all matter. There's very little antimatter. Really,
the only antimatter that we see comes from,
you know, sort of nuclear processes,
you know, both in in stars and in
in, colliders here on Earth. There there's not
a lot of antimatter out there.
And so there are, there's a series of
experiments, base is one of them at CERN,
where they create,
antimatter
in,
in an accelerator,
and they do
really, really precise measurements on it.
And in this case,
researchers on the base experiment
managed to trap a single
antiproton
in an electromagnetic
trap
and use quantum control techniques
to measure the
antiproton's magnetic properties, basically, its spin,
very precisely.
In fact, 16 times more precise
than before.
And, you know, this is very difficult because
first, you have to create the antiprotons, and
that's done in a collider, and they come
out at very high energy. You have to
slow them down.
You have to sort of store them
at very, very low temperatures
and then do your experiments. And at any
point in this process,
if that anti piece of antimatter comes into
contact with matter, which is, of course, everywhere,
it'll annihilate and you lose it. So it's
a really, really difficult process accumulating
all this antimatter.
And then amazingly, you know, they hold it
in their trap
for long enough to do these quantum manipulations
and,
and measure
the, the its properties.
And and and the reason they want to
do this is,
the the standard model,
basically says that matter and antimatter
should be roughly the same except, you know,
for the the obvious that one's matter and
one's antimatter.
So what what the ultimate goal is to
measure the magnetic properties of the antiproton
and compare it to the magnetic properties of
the proton.
And these should be, well, identical
with the exception of a flip in,
in the side the charge on the particle.
And so if they can find even the
most minute
differences between the proton and the antiproton,
that could lead to physics
beyond the standard model
and also tell us why there's more matter
than antimatter
in the universe.
So
exciting experiment, and who knows? Hopefully, they'll they'll
find a difference between the proton and the
antiproton.
I always think with antimatter, we need another
Dan Brown novel to follow angels and demons
when they used antimatter, and that was the
the plot hook.
Now completing our list of the top 10
breakthroughs of the year in physics as picked
by Physics World,
we've gone some for some condensed matter physics
that seems pretty straightforward in principle, but,
it seems to have taken quite a lot
of effort, and that is in making two
dimensional metals.
So, Michael, can you tell us more about
this one?
Yeah. So this breakthrough is about the first
creation of two d sheets of metal.
So since 2004,
we know that some materials can form flat
sheets known as two d materials,
graphene being one prime example.
Such materials are about one atom thick, and
in the case of graphene occur because you
have a layer of atoms that are separated
by gaps between neighboring layers.
This means that you can effectively shave off
layers to make two d sheets.
Things are a bit different, however, for metals.
In the case of metals, atoms are strongly
bounded to surrounding atoms in all directions, which
makes cleaving difficult.
To get around this problem and create two
d sheets of metal, the researchers who are
based in China heated powders of pure metals
and melted them into droplets.
They then applied a pressure of around 200
megapascal, effectively
squeezing the opposite sides of these anvils until
two d sheets of metals were formed.
The team managed to produce five atomically thin
two d metals. That's bismuth,
tin, lead, indium, and gallium, with the thinnest
being around 6.3
angstrom.
The researchers say their work is just a
tip of the iceberg, and they now aim
to study fundamental physics with the new materials.
So watch this space.
So that's all of our top 10 breakthroughs
for this year as picked by Physics World.
We've had some astronomy, some geoscience,
condensed matter,
a bit of particle physics, biophysics, medical physics,
and optical physics.
But to find out who's bagged the overall
top prize for Physics World's breakthrough of the
year for 2025,
Check back on Thursday, December 18,
where we'll reveal the winner in a new
story and in the next episode of the
Physics World weekly podcast.
So a big thank you to Tammy, Margaret,
Michael, and Hamish for joining me today.
And a special thanks to producer Fred Isles.
And thanks for listening, and do join us
again next week for the big reveal of
Physics World's breakthrough of the year for 2025.