Astronomers Have Found a Hole in the Universe So Big, It Raises Troubling Questions（原声文稿）

Point a telescope at a patch of sky near the constellation Bootis, and you'll be looking into a part of the universe where something is missing.

Not a star, not a galaxy, but a whole region of space roughly 330 million light -years across.

By every rule we know, it should hold around 2 ,000 galaxies. Astronomers have found about 60.

For decades this was treated as a curiosity, the emptiest place anyone had ever mapped.

But now a growing number of astronomers think something even stranger is going on.

We may be living inside a hole like this ourselves, one far bigger than Boetis.

If they're right, it could explain one of the most stubborn problems in modern physics, and it could also mean our best model of the universe is wrong.

If you enjoy stories like this, where a strange observation slowly pulls apart something scientists thought they understood, subscribe, because there are plenty more of them out there.

To understand why a hole in the universe is a big deal, you first need to know what the universe is supposed to look like.

On the largest scales, galaxies aren't scattered evenly across space. They're arranged into what astronomers call the cosmic web.

Long filaments of galaxies stretch for hundreds of millions of light years.

Where filaments meet, you get dense clusters with thousands of galaxies packed together. In between are the voids.

Voids are exactly what they sound like. Huge regions of space with far fewer galaxies than average. They aren't completely empty.

A few galaxies drift through them, along with thin gas and dark matter.

But compared with the crowded filaments around them, they're deserts. Gravity helps make them that way.

Over billions of years, matter in slightly less dense regions gets pulled toward the denser regions around it, so the empty parts get emptier and the crowded parts get more crowded. Voids are expected.

The standard model of cosmology predicts them, and computer simulations of the universe produce them all the time. What matters is size.

Avoid a few tens of millions of light -years -wide is normal.

Push into the hundreds of millions, and then billions, and the questions get harder.

That's where this story goes.

In 1981, a team of astronomers led by Robert Kirschner was working on one of the early attempts to map the universe in three dimensions.

The method was redshift.

As the universe expands, light from distant galaxies is stretched toward longer, redder wavelengths, and the farther away a galaxy is, the more its light is stretched.

So if you measure how much a galaxy's light has been redshifted, you can work out roughly how far away it is.

Do that for enough galaxies and a flat picture of the sky becomes a map with depth.

Kirschner's team, which included Augustus O.

Emler, Paul Schechter, and Stephen Schechtman, sampled a few small fields of sky in the direction of Boutis.

As the red shifts came in, they noticed something odd.

There were galaxies in front and galaxies behind, but across a big range of distances in between, there was almost nothing.

At first, the survey turned up just a single spiral galaxy in that gap.

Some called it the loneliest galaxy in the universe.

One odd result in a few small patches of sky could easily be a fluke, so the team went back and measured 240 bright galaxies in the region between their original fields.

Not one had a red shift between about 12 ,000 and 19 ,000 km per second.

In that slice of the universe, the galaxies simply weren't there. The gap was real, and it was enormous.

It became known as the Botus Void, and sometimes the Great Nothing.

It sits roughly 700 million light -years from us, and it's usually given a diameter of about 330 million light -years.

That's well over 100 times the distance from the Milky Way to the Andromeda Galaxy, our nearest large neighbor.

Astronomers have kept searching it in the decades since, and they've found more galaxies inside, about 60 so far.

A region that size in an ordinary part of the universe should hold about 2 ,000.

Astronomer Greg Aldering summed up the emptiness with one comparison.

If the Milky Way had been in the center of the Bode's void, he said, we wouldn't have known there were other galaxies until the 1960s.

In our actual position, it was the 1920s when Edwin Hubble showed that faint smudges like Andromeda were separate galaxies far beyond our own.

From the middle of Boutes, the nearest galaxies would have been so distant and faint that astronomers could have spent another 40 years thinking the Milky Way was the entire universe.

A civilization sitting inside a void wouldn't necessarily know it was inside one.

It would see a quieter, emptier sky and assume that simply what the universe looks like.

Boutes isn't the only giant hole out there, and some of them seem to leave marks on the oldest light in the cosmos.

In 2004, astronomers studying the cosmic microwave background found something that didn't quite fit.

The cosmic microwave background is the faint afterglow of the Big Bang, light released when the universe was only about 380 ,000 years old.

It's remarkably uniform, with tiny temperature differences that astronomers map in great detail.

Our models predict warm and cool patches of various sizes.

But one region, in the southern sky, was bigger and colder than expected. It became known as the cold spot.

In 2015, a team led by Istvan Saputi at the University of Hawaii went looking for something in the foreground that might explain it.

Using data from NASA's WISE satellite and the Pan -STARS -1 telescope, they found a vast underdense region lined up with the cold spot.

It's now called the erudanus supervoid.

It's roughly 1 .8 billion light -years across and about 3 billion light -years away.

At the time, it was described as possibly the largest individual structure ever identified by humanity, and it was defined by what was missing.

The proposed link between the two is subtle, as light from the early universe crosses a huge void on its way to us.

The changing gravity of that empty region can drain a little of its energy. The light comes out slightly colder than it went in.

The research team was careful to say the supervoid probably doesn't explain the whole cold spot.

But they also said it's very unlikely that a structure this large and a cold anomaly this unusual would sit in exactly the same spot by coincidence.

So now we have voids hundreds of millions of light years wide and a supervoid nearly two billion light years wide that may have left a mark on the Big Bang's afterglow.

They're out there, far away, interesting but distant.

The question that has kept cosmologists busy through the 2020s is closer to home. What if we're inside one?

To see why that question matters so much, we need to talk about one of the biggest arguments in modern cosmology, the Hubble Tension.

In 1929, Edwin Hubble published evidence that galaxies are moving away from us and that But the farther away they are, the faster they recede.

The universe is expanding.

The rate of that expansion today is called the Hubble constant.

It's measured in kilometers per second per megaparsec, and a megaparsec is about 3 .26 million light years.

A Hubble constant of 70 would mean that for every megaparsec of distance, a galaxy appears to be moving away about 70 kilometers per second faster.

It sounds like a number you'd measure once and move on, but there are two very different ways to get it, and they don't agree.

The first uses the early universe.

Missions like the European Space Agency's Planck satellite mapped the cosmic microwave background in great detail.

Plug that map into the standard model of cosmology, called Lambda CDM, and you can calculate how fast the universe should be expanding today. way. That method gives about 67 points.

The second uses the nearby universe. Astronomers build what's called a distance ladder.

They start with stars whose true brightness is known, like Cepheid variables, which pulse at a rate tied to how luminous they are.

Use those to measure distances to nearby galaxies, then use those galaxies to calibrate brighter markers, like type 1a supernovae, which can be seen much farther away.

Step by step, the latter reaches deep into space.

Compare those distances with the galaxy's red shifts and you get a direct measurement of the expansion rate.

That method gives about 73 .67 versus 73.

A gap of roughly 9 % doesn't sound dramatic, but both measurements have become extremely precise and neither value will budge.

For years, many physicists assumed the problem was hiding somewhere in the distance ladder.

Maybe dust was dimming some cepheids or crowded star fields were blending their light.

So the latter was rebuilt again and again with new telescopes and new methods.

When the James Webb Space Telescope came online, it gave astronomers a much sharper view of those same cepheids.

The SH0ES team, led by Nobel laureate Adam Reese, used Webb to recalibrate the measurements and still got about 73 .5.

Then in 2026, the problem got even harder to ignore.

An international group called the H -Zero Distance Network Collaboration published a result in the journal Astronomy and Astrophysics.

Instead of relying on one ladder, they tied together almost every independent distance method astronomers have—cephiids, red giant stars, mirror variables, water masers orbiting black holes, two different kinds of supernovae, the way galaxies spin and more.

All of it was combined into one network.

The result was 73 .50, with a precision of just over 1%.

Removing Cepheids barely changed it. Removing red giants barely changed it.

Swapping supernovae for galaxy -based methods shifted it by less than a tenth of a unit.

it. That puts the local measurement 7 .1 sigma away from the value predicted by the early universe and the standard model.

In physics, 5 sigma is the usual bar for a discovery.

This disagreement is well past it. So something is wrong.

Either there's an error that has survived every check, or the standard model is missing something about how the universe has evolved.

Since the 2010s, theorists have proposed new forms of dark energy, extra particles, modified gravity, and changes to the early universe.

None of them has cleanly fixed the problem.

But there's another possibility, and it doesn't require new physics in the early universe at all.

Maybe the universe isn't expanding faster. Maybe it only looks that way from where we're standing.

In 2013, three astronomers at the University of Hawaii, Ryan Keenan, Amy Barger, and Lennox Cowey measured how much near -infrared light galaxies give off at different distances from us.

Infrared is useful here because it's less affected by dust and traces the stars that make up most of a galaxy's mass.

If matter were spread evenly around us, the amount of galaxy light per unit of volume should stay roughly the same as you look farther out. It didn't.

Nearby, the numbers came out lower.

Farther away, they rose toward the cosmic average.

The pattern suggested that our corner of the universe is underdense.

We seem to sit in a region with fewer galaxies than average, stretching out about 300 megaparsecs in every direction, or roughly a billion light -years.

That makes the whole region around 2 billion light years across.

It's now called the KBC void, after the three astronomers, and sometimes the local hole. Estimates of how empty it is vary.

The original study suggested our surroundings could be close to half as dense as the universe overall.

More recent models favor something milder, about 20 % below average.

Either way, the Milky Way would sit near the middle of it.

Remember Aldering's point about bowtas. From the inside, a void doesn't look like a hole.

It looks normal. You can't step outside and see its edges.

The only way to find it is to count everything around you and notice there's less than there should be.

That's exactly what Keenan, Barger, and Cowie may have done.

The KBC void would be several times wider than the and this time, we're the ones sitting in the empty part.

Here's how a hole could fake a faster universe.

Picture yourself in the middle of a low -density region.

All around you, at the edges of the void, there's more matter.

More galaxies, more dark matter, more gravity.

That denser material pulls on everything inside the void, so galaxies near us are dragged outward, away from the center, toward the crowded walls.

Now think about what an astronomer measures.

Redshift tells you how fast a galaxy is moving away.

Normally, that motion comes from the expansion of space.

But inside a void, galaxies get an extra push outward from gravity.

Their redshifts come out a little higher than expansion alone would produce.

Measure enough of those galaxies, calculate the expansion rate, and you'd get a number that's too high.

Not because the universe is expanding faster, but because your neighborhood is draining outward.

Indranil Banek, a cosmologist at the University of Portsmouth, and one of the main researchers behind the local Void idea put it this way.

The Void would cause matter to be pulled by gravity towards the higher density exterior of the Void, leading to the Void becoming emptier with time.

In this picture, both measurements are right.

rate. The early universe gives the true global expansion rate of about 67.

The distance ladder correctly measures what's happening around us, about 73. But what's happening around us isn't typical.

We're the ones in the strange place. It's a neat solution, and an unsettling one.

It means that for nearly a century, part of what we believed about the whole universe may have been shaped by the particular hole we happen to live in.

An idea like that needs evidence, and in 2025, it got some from an unexpected source. Sound.

In the first few hundred thousand years after the Big Bang, the universe was a hot, dense mix of matter and light.

Pressure waves rippled through it, like sound waves moving through air.

When the universe cooled enough for light to escape, those waves froze in place.

Their imprint survives today, as a slight preference for galaxies to be separated by a particular distance, about 500 million light years.

Astronomers call these Baryon acoustic oscillations, or BAO.

Because that distance is known, it works as a cosmic ruler.

Measure how big the ruler looks at different distances, and you can trace how the universe has expanded over time. A local void should distort that ruler slightly.

The outflow inside the void changes the relationship between how far away things appear year, and how big the ruler looks on the sky.

So Banek and his colleagues asked a straightforward question.

If we really live in a hole, does 20 years of BAO data show the fingerprint?

In July 2025, Banek presented the results at the Royal Astronomical Society's National Astronomy Meeting in Durham.

The study, published in the monthly notices of the Royal Astronomical Society, compared to model with a local void against a model without one. Tune to match the Planck data.

Across two decades of BAO measurements, the team found the void model was about 100 million times more likely than the void -free model.

In their analysis, the tension within the BAO data dropped from 3 .3 sigma to somewhere between 1 .1 and 1 .4 sigma.

In plain terms, the sound of the Big Bang appears to be consistent with us living in a hole. The work hasn't stopped there.

In February 2026, Bannock and colleagues published a broader case for the local void as a solution to both the Hubble Tension and the BAO measurements.

Then the team tested the idea against the newest and most detailed BAO data, the second data release from DESI, the Dark Energy Spectroscopic Instrument.

That's a project measuring the positions of millions of galaxies from a telescope in Arizona.

In that analysis, the standard model without a void came out slightly ahead.

But the researchers concluded that a local void large enough to solve the Hubble tension cannot be ruled out. The void model fit the data almost as well.

So the whole hasn't been confirmed, and it hasn't gone away either. And that's where the troubling questions start. Suppose the void is real.

Suppose we really are sitting near the center of a region about two billion light -years across and significantly emptier than average.

That would solve one problem and create another.

The standard model of cosmology doesn't just predict that voids exist. It predicts how big and how empty they can get.

Structure in the universe grows at a certain pace, set by gravity, dark matter and the expansion of space.

Over the age of the universe, Lambda -CDM only allows so much emptiness to form on any given scale.

And voids billions of light -years wide, with the depth the KBC measurements suggest, shouldn't really happen.

In 2020, Moritz Hazelbauer, Indranil Bannock, and Pavel Krupa tested exactly that.

They took the KBC measurements and compared them with the Millennium XXL Simulation, one of the largest simulations of the standard model ever run, tracking the growth of structure across a vast virtual universe.

They asked how often a void like ours appears.

Their answer was that the KBC void puts the standard model under 6 .04 sigma of tension.

In other words, in a universe that follows lambda CDM, a hole like the one we may be living in is almost impossible.

That puts cosmologists in an awkward spot.

If there's no void, the Hubble tension is still unexplained, and something in our understanding of cosmic expansion is broken.

If there is a void, the Hubble tension may be explained, but the void itself breaks our understanding of how structure forms. Either way, the standard model takes damage.

Some researchers, including Hazelbauer, Bannock, and Krupa, have pointed to a possible alternative, modified gravity.

A theory called Milgromian Dynamics, or MOND, proposes that gravity behaves differently at very low accelerations.

In a cosmology built on that idea, structures grow faster, and enormous voids like the KBC void can form naturally.

Work testing MOND -based models on scales of billions of light -years is still going on.

Most physicists remain unconvinced by MOND, and it has serious problems of its own.

but the fact that a giant void could push serious researchers toward rewriting gravity shows how much is at stake. There's also a quieter discomfort.

For the void to explain the Hubble tension, we have to sit near its center.

For centuries, one of the guiding principles in astronomy has been that we're not in a special place.

Earth isn't the center of the solar system. The sun isn't the center of the galaxy. galaxy. And our galaxy isn't the center of anything. Finding ourselves near the heart of a rare, giant hole would be an uncomfortable coincidence.

It's not impossible, but it's the kind of thing that makes physicists nervous.

Still, plenty of astronomers don't think the hole is there at all.

In 2019, Adam Rees, Dan Skolnick, and Ben Kenworthy went looking for the void in the place it should be easiest to see, supernovae.

They used nearly 1 ,300 type 1A supernovae spread across a wide range of distances.

If we were sitting in a deep void with a sharp edge, the expansion rate measured from those supernovae should jump as you cross from inside the hole to outside it. They didn't find that jump.

Their analysis concluded that large local under densities, more than 20 % below average, were inconsistent with the supernova data at 4 to 5 sigma.

Their paper's title was blunt. Local structure does not impact the measurement of the Hubble constant.

In July 2026, another team, Tomasso Moretti, Noemi Fruchante and Giovanni Verza, ran their own analysis using models where dark energy can change over time, as some recent DESI results have hinted.

They found that a KBC -like void could reduce the disagreement between the local measurements and Planck to about two Sigma.

That's a big improvement, but by their judgment, it still isn't enough.

Local underdensities can affect the measurements they concluded, but they do not resolve the Hubble tension.

So the debate is genuinely open.

Supporters point to galaxy counts and 20 years of BAO data.

Critics point to the supernovae and to calculations suggesting the void can't close the whole gap.

Banach's group is now working on the supernova question directly, with a study led by Sergej Mazarenko examining whether a properly modeled void actually conflicts with supernova data.

They're also preparing tests using cosmic chronometers.

Those are old galaxies that stopped forming stars long ago, and their aging populations act as clocks, recording how fast the universe has expanded at different times. More data is coming fast.

Last, DESI is still mapping millions of galaxies.

The European Space Agency's Euclid Telescope is surveying a huge share of the sky.

Rubin Observatory in Chile is starting to catalog supernovae and galaxies at a pace astronomers have never had before.

If a whole 2 billion light -years wide surrounds us, these surveys should find it.

And if they don't, the Hubble tension goes back to being a puzzle without a clear answer.

Think back to that thought experiment about bow -oats, a civilization in the middle of the Great Nothing, looking up at a sky that seemed empty, sure that its galaxy was the whole of creation, simply because of where it happened to be born.

It's easy to picture them and feel a little sorry for them.

They'd be measuring the universe correctly and still getting the wrong idea about it.

We may be in the same situation on a much larger scale.

Every measurement of the nearby universe we've ever made could have been taken from the inside of a hole, with matter flowing quietly outward around us, nudging our numbers and making the universe look like it's racing away faster than it really is.

If that's true, it explains one of the deepest mysteries in physics, and it raises an even bigger one. How a void that size could form at all.

And if it isn't true, then the universe really is expanding in a way our best model can't account for. There's no comfortable outcome here.

Either we're sitting in a hole or something more fundamental about the cosmos is still waiting to be found. So where do you land?

Are we really living inside a giant void or is the answer to the Hubble tension still somewhere else? Drop your take below.

And if you'd like to find out whether the hole is really there once the new surveys report back, subscribe, and keep following the strangest discoveries in the universe as they come in.