A considerable amount of the Universe is lacking. Scientists assume they could have simply discovered it

You might have heard of darkish matter earlier than. It’s the unusual, invisible, undetected stuff that makes greater than 1 / 4 of all of the matter within the Universe.

It cannot be seen, however astronomers know it is there as a result of it is appearing like a form of gravitational glue, holding galaxies collectively.

If we rely the quantity of ‘regular’ matter in galaxies – stars, mud and issues we will truly see – there’s not sufficient mass to have the gravitational pull to stop galaxies from tearing aside as they quickly rotate.

The further stuff known as ‘darkish matter’. Astronomers do not know what it’s, and it turns on the market’s rather a lot they do not know about unusual matter, both.

Quite a whole lot of this regular matter is lacking; unaccounted for. At least it was.

Astronomers now assume they may have discovered it, and it has been hiding in plain sight all alongside.

Liam Connor is an assistant professor of astronomy at Harvard University, researching quick radio bursts and AI in astrophysics, and constructing giant radio telescope arrays.

We spoke to him about ‘regular’ matter originally of the Universe, why it appears to be lacking, and why scientists assume they may have discovered it.

What is regular or ‘ordinary’ matter?

When astronomers discuss regular matter, we’re referring to baryons.

By that, we simply imply ‘the stuff of atoms’ – issues like protons and neutrons. 

How did we discover out among the Universe’s unusual matter was lacking?

We can see leftover gentle from the Big Bang. We name this the cosmic microwave background radiation or CMB.

Fluctuations within the cosmic microwave background give us a snapshot of how issues had been round 400,000 years after the Big Bang.

It’s a form of ‘baby photo’ for the Universe, which tells us how a lot matter there was, each regular and darkish.

All these atoms ought to nonetheless be right here 13.8 billion years later.

But, in case you rely the celebs and planets and dirt you’ll be able to see together with your telescope, you’ll discover a vital quantity of matter seems to be lacking.

Where did you discover this lacking matter?

Hiding! It seems that many of the matter within the Universe is nicely exterior of the haloes of galaxies.

It’s a form of wispy, diffuse state that we name the intergalactic medium.

If you zoomed out on a picture of the Universe and form of blurred your eyes, the intergalactic medium would appear like a fuzzy cosmic net.

We used objects known as quick radio bursts to assist us discover this matter. 

What is a quick radio burst?

Fast radio bursts, or FRBs, are pulses of radio waves. They normally final round a millisecond, however may be as brief as 10 microseconds – so that they’re very quick.

They had been found in 2007, so a comparatively ‘new’ cosmic phenomenon. In the final decade, we’ve proven that FRBs are coming from billions of lightyears away.

How did you employ FRBs to work out that there was a lot lacking matter?

The order of operations is like this.

You see a little bit blip with a radio telescope, and you’ll pinpoint the place it’s on the sky and which galaxy it may very well be coming from.

You then use an optical telescope to observe it up, which provides you a fingerprint of the galaxy. It tells what kind of galaxy hosts the FRB, and in addition how distant it’s.

This tells us how a lot the radio waves had been slowed down by intervening matter, which relies on the density of matter it interacts with.

By doing this, we will work out the typical density of regular matter within the Universe.

A pattern of, say, 50 or 100 FRBs tells you numerous about the place the lacking matter is hiding. 

What may very well be inflicting FRBs?

There’s no consensus but.

Many individuals would say neutron stars, that are what’s left behind when a really giant star explodes and the remaining matter isn’t fairly huge sufficient to kind a black gap.

We assume FRBs may come from a sort of neutron star, that are comparatively younger and extremely magnetised.

Whatever their origin, the truth that you’ll be able to observe these radio bursts billions of lightyears away signifies that their supply should be extraordinarily luminous.

There aren’t many candidates for that kind of object.

What are the implications of your discovery?

The most attention-grabbing facet of our analysis paper will not be that we discovered the lacking unusual matter, however that this matter was contained exterior of galaxy haloes.

When galaxies kind, they slosh matter round in a course of known as suggestions.

Our outcomes counsel that there’s a robust and environment friendly suggestions course of that form of smooths out the matter within the Universe. 

What’s subsequent on your group?

On some degree, the enjoyable actually begins now.

For a few years, we didn’t know the large-scale distribution of regular matter within the Universe. We couldn’t even discover it.

Now, there are a number of unanswered questions that we will discover, like what’s the distribution of gasoline within the Universe and the way does that relate to the expansion of supermassive black holes? 

It additionally has a big impact on precision cosmology.

For upcoming telescopes and tasks just like the Nancy Grace Roman or Euclid house telescopes, realizing the place unusual matter is can cut back systematic errors and allow us to extra meaningfully interpret the information we report.

This interview appeared within the October 2025 situation of BBC Sky at Night Magazine