Is everything we know about the universe wrong?

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Welcome to the podcast of BBC Inside Science.

First broadcast on Thursday, the 27th of March, 2025.

Hello, coming up.

A meteorite, a maths prize, and the mysterious substance that makes up 68% of the universe becomes slightly less mysterious.

Plus, Penny Sasha, managing editor at New Scientist, has dropped by with some stories that have captured her attention this week.

Penny, welcome and want to give us a tease about what you'll be talking about later?

How about the small matter of life on Mars, maybe?

Oh, love it.

Yeah.

Okay.

Looking forward to that.

But we start with something massive that controls the ultimate fate of the universe and some new research that could turn our current thinking on its head.

Did Albert Einstein have it all wrong?

New findings on dark energy are challenging one of his theories and our understanding of the universe.

New research on dark energy suggests it may be weakening.

And if this trend continues, this is what matters to you.

It could cause the universe to eventually collapse.

I love it.

News leaving out a crucial time scale there.

I should say, don't worry, universe not collapsing in our lifetimes.

But over the past week, one conversation has dominated the world of physics.

Have we found a new way to understand the universe?

And if so, what might that mean for future research that has anything to do with how we all came to exist and what might happen to us next?

All of which we're going to unpick now.

And helping me to do that are Professors Catherine Haymans and Andrew Ponson, both of whom have really put in the decades to understanding our universe.

Hello, both.

Hello.

Hello.

Andrew, you first.

This is to do with dark energy.

So we're talking about the recipe of what makes up the universe.

You and I are made of atoms and so is everything that we can see, but that's a mere fraction of what's out there, right?

Yeah, as far as we can tell, that's only about 5% of everything that's out there.

And the remainder is made up of two quite mysterious substances.

One of them is dark matter, which we talk about regularly, but is not at the heart of this.

Dark energy is really a name that we give to a phenomenon that we don't really understand.

I mean, it comes from the fact that we can see that the universe is expanding.

I mean, we've known that since the early 20th century, in fact.

But more than that, we can see that it's not just expanding, it's expanding at an accelerating rate.

Now, one of the headlines, Andrew, this week was: Dark energy experiment challenges Einstein's theory of universe.

So, before we turn everything on its head, can you explain how Einstein fits into this original idea on how the universe expands?

I mean, I think that's a bit of an overblown way of putting it, but it is true that Einstein had an idea that loosely maps onto this idea of dark energy.

So Einstein thought deeply about gravity and came up with a theory called general relativity, which is our best explanation of how it works.

But within that theory, he anticipated the possibility that as well as a pull, there could also be a push, a sort of anti-gravity force, but that would work on extremely large scales.

Catherine, bringing you in here.

So, what then does this new set of findings tell us about dark energy?

Einstein's theory comes from what we call the cosmological constant.

And so, the dark energy just changes with the volume of the universe.

So, the bigger the universe gets, the more dark energy there is, and that speeds up the expansion of the universe.

But, what the team at the Dark Energy Spectroscopic Instrument have found, DESI,

is that it's not a constant, or at least there's hints of that,

and that the rate that the universe is accelerating is slowing down.

Is that surprising?

I mean, that seems more logical than acceleration to me.

Well, it depends what you think is causing dark energy.

This instrument was designed to validate this theory, this very nice theory that we have of our universe that explains a lot of things in our reality.

And they tested a model where they said, okay, well, we'll allow a small tweak.

We'll say, okay, maybe Einstein's cosmological constant isn't a constant and we'll allow it to vary with time, not expecting it to show that, oh, actually, no, it is varying with time, which sort of ticks that theory off the list, opening up to a whole zoo of different other alternative theories out there, which which on the one hand is excellent because we really don't understand what dark energy is.

And so it's good to have an opportunity to explore these other different theories and what they predict.

But unfortunately, it leaves us no closer to really understanding the origin of this dark source of energy.

Catherine, how was this new clump of data collected?

With this absolutely phenomenal instrument.

It has five thousand robotic eyes.

So the telescope slews to look at a patch of sky and these tiny little robots line up optical fibers on the positions of all of the galaxies in the region of sky that the telescope is looking at.

It collects that light and breaks the light up into its different energy ranges which gives you what we call a spectrum which allows you to measure the speed that these galaxies are moving away from us.

And if we're measuring expansion rates then that's what we want to know.

It has measured these distances to 15 million galaxies and quasars, huge volume of galaxies, and what it's looking at is the distribution of those galaxies.

Now there's a trick that we can use in cosmology where we can use those galaxies as kind of a ruler in space.

And you can use that ruler to measure distances, combining that with the speeds, that's what gives you the expansion rate.

But it's an absolutely phenomenal instrument and it's huge as well.

People should Google it and just to look at this wonderful instrument with these 5,000 robotic eyes that can reconfigure in just two minutes to a new set of galaxies as the telescope slews across the sky.

Wow.

Andrew, can I ask what you think of this data, this new data?

So the new data is absolutely beautiful.

You know, this is an amazing instrument and the analysis has been led by an incredible team.

But they themselves have said you really have to be cautious about these results.

And I completely agree with that attitude.

And I think we have to be careful about becoming carried away here.

You know, if you just take these new data on their own, then they don't actually tell you that the original account we had of the accelerating universe, this sort of Einstein's cosmological constant that we were talking about, these data do not disprove that in any sense.

The way that the claim that there's something weird going on has been constructed is by comparing these data with data that have been taken previously.

And it's when you compare those two bits of data that you get led to this conclusion.

And the trouble with that is that whenever you compare two sets of data, you have to be really confident that you understand every last subtle detail.

Right, so there might be assumptions in your thinking.

Absolutely.

And I mean, there almost have to be assumptions in your thinking because these two types of data are very different.

The way I think about this

is, you know, whenever you make measurements, you have to be careful about exactly how that's calibrated.

So even something as simple as, you know, we like to measure my son growing up.

You know, we have a height chart that we measure him on.

And I remember, you know, one day it fell off the wall.

and then and then we reattached it to the wall and shortly after that we measured him again and it looked like he'd shrunk and for a moment we're like what's going on but of course what had happened in reality is that the the chart must have been at the wrong level beforehand Maybe it was slipping down or something So when we put it back on the wall and we carefully calibrated it back onto the wall Then we probably got a better measurement and then comparing with the older measurements We reached a crazy conclusion or rather we didn't because we you know we realized what must have have happened now the data that we're talking about here are far more carefully collected Than than that of course.

So it's nothing as simple as that.

But nonetheless, these measurements are incredibly complex and you can interpret them in lots of different ways.

So I think we just have to take a breath and wait and see how this pans out over the coming years as more data comes in.

What would having a more definite understanding of dark energy actually mean, Catherine?

Yeah, so dark energy determines the fate of our universe.

I'm a big fan of the model when the universe collapses, because then you kind of get this rebounding universe that just keeps collapsing and expanding forevermore.

All the data at the moment points to the fact that that's not going to happen.

We have a very sad death of our universe planned called the Big Freeze, where the universe just keeps expanding forever as the stars burn out their last fuel and it becomes a very empty, dark place, which always made me a bit sad.

So, if dark energy is weirder than we thought, and maybe it switches off, maybe it might even cause a collapse, then maybe we might have a nice hot, fiery future for our universe.

What happens now?

Where do we confirm this new data, Andrew?

The great news is there is plenty of data on the way, and we will find out whether this is right or not.

And so what you would hope for is that if these measurements turn out to be confirmed, then you can start making progress on those really big questions.

Well thank you so much.

Professor Catherine Haymans, Scotland's astronomer royal from the University of Edinburgh and Professor Andrew Ponson, cosmologist from Durham University.

And if all of this chat has left you with questions, the Inside Science team is here for you.

Our Easter programme is going to be a listener's questions special, so we need your queries.

Anything from the mysteries of the universe to any mysteries lurking inside your head, BBCInsideScience at bbc.co.uk is the place to send them.

No question too big or small for the team.

Let's stay with mysteries of space because four years ago a bright and beautiful shooting star made quite the entrance to our atmosphere, its fiery streak across the sky picked up by dash cams as it fell.

It was a space rock, and part of it dropped on a family's driveway in Winchcombe, Gloucestershire.

The Winchcombe meteorite is revealing all sorts of clues about the early solar system and there's still a lot more to uncover, as Gareth Mitchell reports.

Well, I'm just hopping off this bus, having made my way from Milton Keynes here to the campus of Cranfield University.

And today is a big day.

A team has come all the way down from Glasgow to subject the Winchcombe meteorite or fragments of it to their closest analysis yet using state-of-the-art imaging equipment in a rather anonymous-looking building just over the road from this very bus stop.

The famous rock fragments and the scientists are waiting for me inside, including Dr.

Luke Daly, reader in planetary geoscience at the University of Glasgow.

The meteorite is a carbonaceous chondrite.

These are one of the rarest groups of meteorites we have, but they're also possibly the most exciting and important samples we have because they are chock full of water and chock full of organic material.

They're basically all the ingredients and building blocks a growing planet needs to have the opportunity for life to emerge on it.

And in fact, we think that that's how the organic material on Earth and the water was delivered to Earth was by delivery of these water-rich asteroids when the Earth was first forming.

And analysis of this particular meteorite over the last four years has so far revealed that it predates the Earth and that its parent asteroid had a bruising journey through the solar system.

It shattered and reconstituted many times.

Eventually, a chunk broke off and was propelled towards Earth, only to propel the unsuspecting Wilcox family in Winchcombe into the headlines in 2021 when some of the rock landed on their driveway.

Here at Cranfield, Luke Daly wants an even closer look.

He's brought Glasgow University postgraduate research student Heather Gibson with him.

Wishco meteorite travel from west to east, so the main math fell on the famous Wilcox driveway and alarmed the guinea pigs.

But there are other the fieldstone was a bit further west, and so we had samples that came from Woodman Cote, a village again further west.

We wanted to have a look at those and see whether they were the same as the Wilcox and the Fieldstone or were they different?

Well, thank you, Heather.

Well, today is a really big day because the team have come all the way down from Glasgow to see you, Diane.

This is Dr.

Diane Johnson, who's a senior technical officer here at Cranfield University.

And I can see on the desk here, you have a plastic box with a number of samples in.

So these are tiny fragments, just a few millimetres across, aren't they?

From the different landing sites that the Winchcombe meteorite ended up in.

That's right, yeah.

We've got a range of different samples from Winchcombe, which are different lithologies, so different textures, different compositions.

They're very small samples, typically centimetres to millimetres and the entire sample holder it's set in is maybe just an inch across in diameter.

I'm just blown away that on the desk in front of us just sitting there next to your thing with all your pens and pencils in are fragments from the early solar system and they look they're just like little almost like bits of flint they look like to me.

They're very dark aren't they?

That's right yeah I mean a lot of these really really primitive meteorites are very dark to the eye they don't really look very special.

They're very dark and crumbly looking nothing that you'd look twice at really but when you consider where they're from and their age about four and a half billion years it's pretty staggering to just sit next to them and look at them with your eyes.

Yeah.

Soon the analysis is underway.

Diane has an electron microscope that images surface details of the rock.

Bolted onto that is a spectrometer.

That's some kit that shows what the sample's made of.

And in my slightly unscientific way, I'm doing my best to describe the setup.

So the facility itself here, you have a whole bank of screens, but the business end, it looks to me a bit like, say, an office printer, but

which doesn't sound very glamorous.

But the glamorous part is the amount of kit that's kind of plugged into it and sort of coming out of it.

So you have three or four quite large assemblies, like metal boxes basically, with a whole load of wires and sensors coming out of them, which are the different elements of this equipment.

And one very exciting box is the spectrometer, isn't it?

So, tell me what the spectrometer does.

That's right, it's a time-of-flight secondary ion mass spectrometer, so we can see really minute quantities present, and we also see its distribution in three dimensions.

So, we're looking at the boundary between two different grains, and we're seeing magnesium, we're mapping magnesium, and we can see as time progresses when there's a lot of magnesium where there's less magnesium.

Is that something you'd expect?

Do they always have magnesium in?

We would expect magnesium with silica and water sort of like netted in there.

What else is beginning to emerge?

So I have to change the view to change to a new element, so I can change to calcium.

Ah, okay, so you've got a menu of different things you can look out for.

Okay, like a drop-down menu, so you're selecting calcium.

Yes, um, Diane helped me work that out.

So there we go, there's calcium, and you can see that it's in a different area of the map than the magnesium, which would we kind of expect.

We can look at iron as well.

Iron is another common positive iron that we see in these meteorites.

We can look at that as well.

They can form some very interesting structures that kind of look a little bit like worms.

We're very careful that they just look like worms, not actual worms.

Yes, if they found actual worms, I think I would have stumbled on the scientific discovery of the century.

But hey, magnesium, calcium, and iron, I'll settle for that.

Meanwhile, at the facility, a couple of hours soon pass.

Well, these scans take quite a while.

So, in fact, I've left Luke and Heather and Diane to it for a good few hours.

And I've been nosing around the university, but I'm just going to come back into

the room here and see how they're getting on.

Hello, folks.

Hello.

Here we are.

You're still here.

Good.

So,

have you had a busy few hours?

Yeah, it's kind of interesting.

We're seeing these microtextures and relationships between the minerals we're seeing because we're able to get this really detailed resolution.

While we can't say anything conclusive about what it all means for, like, you know, origin of the solar system, delivery of water to the Earth, and how these asteroids have evolved in space just now, it's promising that we're seeing these interesting microtextures.

It's not just about the raw data that's coming off the microscope, it's about us all working together and collaborating, which is kind of the nice bit about science, getting to work with fun people.

Luke Daly, ending that report from Gareth Mitchell.

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This Wednesday saw the announcement of the winner of this year's Arbor Prize.

It's kind of like the Nobel Prize for Maths and is awarded by the King of Norway for outstanding scientific work in mathematics.

The trouble with maths on the radio is that much more than physics or biology, it's a very visual subject.

Numbers are easier on the eye than the ear.

Luckily, science writer Tamandra Harkness was in Oslo for Wednesday's big announcement, so I set her the challenge of explaining the maths that won the prize for Professor Masaki Kashiwara in just three minutes.

I'm afraid even the chair of the Arbel Committee, which chooses the winner, says this year's maths is exceptionally abstract, but I'll give it my best shot.

I see Masaki Kashiwara as the Isambard Kingdom Brunel of mathematics, prolific, inventive, and with a talent for building bridges between parts of mathematics that seemed completely separate.

Here's just one example.

He invented a new way of understanding the symmetries of mathematical objects.

Many everyday objects combine different kinds of symmetry.

A plain square tile, for example, has rotational symmetry.

Turn it through a quarter, half, or full turn and it still looks the same.

It also has reflective symmetry, along a diagonal line between opposite corners or in a line splitting opposite sides in half.

And it has translational symmetry, like sliding sideways across a regular tiled floor.

Some objects, like spheres, have an infinite number of symmetries.

You can rotate a sphere in any direction, around any axis, and it still looks the same.

Or you can reflect it in any plane that cuts it in half, which is an infinite number of planes.

Mathematicians describe these combinations of symmetries using group theory.

Think of a symmetry group as a set of all the ways you can move an object and have it still look the same, with a rule for combining those moves.

Cashiwara found a new way to understand these combinations of symmetries by bringing in a completely separate branch of mathematics called graph theory.

Now I'm afraid graph theory is nothing to do with the kind of graph you probably do at school with an x-axis and a y-axis.

What mathematicians call graph theory is a way of making simplified models of systems as nodes connected by links.

If you ever had a a construction toy with plastic balls joined together with straws, you have the idea.

Railways, plumbing systems, even computer networks can all be modelled with graph theory.

What Kashiwara did was bring together graph theory and groups that describe combinations of symmetries.

He found a way to represent the combined symmetries of an object as a graph of nodes connected by links.

He called this new invention a crystal basis, and mathematicians have been using it to solve problems for nearly 30 years.

It's just one of many bridges he's built between mathematical continents.

Thank you, Tamandra Harkness, and with 15 seconds to spare.

That was impressive.

Penny Sachet, managing editor at New Scientist, is still here with me.

Hello, Penny.

Hi, Em.

So you've sat through us covering the missing stuff in the universe, space, time, tricky maths, and meteorites.

What's left to talk about?

What a treat.

You know what?

I'm really surprised to be bringing you a few findings about possible life on Mars, because this isn't something that I've ever really been interested in at all.

I'm always much more distracted about the life we know we have.

But the last few weeks there's been a few pieces of new discoveries, new analyses, which I think are actually starting to get really interesting.

Okay, so a sceptic has been tipped off.

Not so much a sceptic.

I'm open to there being life elsewhere in the universe.

Yeah, yeah.

I just don't normally find the science that interesting.

But guilty secret there.

So, yeah, what is it?

What's tipped you over?

So one of them, there was this finding published on Monday, and that's the largest organic compounds ever found on Mars.

So these were found by the Curiosity rover in a rock sample that's about 3.7 billion years old in an ancient lake bed.

So these are the kinds of places that they're looking for possible signs of former life on Mars because lakes might have been nice places to live once upon a time.

And what they found were alkanes, so that's kind of these organic chains of hydrocarbons about 10 to 12 carbons in length.

And now work on Earth suggests that these probably came from the heating of the kinds of acids, like fatty acids, that, yes, they do exist anyway in rocks.

but they're very common in life.

So it's very possible that these kind of longest organic compounds that have ever been found on Mars might have come from, say, the degradation of a cell wall or life that was once there but is no more.

And that really sort of caught my eye because a few weeks ago, there was a big space conference in Texas, and there they were talking about some even cooler rocks, really, from a different lake bed, different rover, but around the same age.

And these have these incredible sort of speckled patterns in them, which are really like the kinds of calcium sulfate chemicals that you sometimes see around these kinds of patterns on Earth, microbial patterns.

And they're doing all kinds of interesting chemical analyses to understand, you know, were these once microbes 3.7 billion years ago.

And so what's got scientists so excited then?

The key bit here is the sulfate, the sulfur, they've just found is reduced.

So that means it's gained an electron.

The reason that's interesting is there's two ways to get that.

One, it could be produced by redox reactions, which is this way that microbes can produce their own energy.

Or you could heat up a rock really high, well, quite high,

and that could happen abiotically.

But there's absolutely no sign, like large crystals, or the kinds of things you'd expect in geology if they'd been heating.

So, that's a very complicated way of saying these are two quite tantalizing hints of microbial chemistry, the kind that we do see on Earth.

It's interesting to note that the bar for what they're looking for is much lower than it would be, you know, here on Earth you'd be looking for a fossil, hopefully.

Yes, yeah.

Well, what we don't know, I guess, is whether these speckled patterns kind of are fossils, but they do actually date back to almost exactly the same time that we have the earliest fossil evidence of microbes on Earth.

How cool would that be if they were sort of evolving and living at the same time?

Yeah, so the hunt for life when you don't actually know what form the life would take.

I know, it is all sort of premised on life on Mars once having been very like life here, which, I mean, we don't know if that has to be true.

We don't know.

No assumptions made in science.

Now, Penny, the chance to blow your own trumpet, or rather, new scientists' trumpet.

They've done a really interesting freedom of information request relating to how our politicians use AI.

Do tell.

Yeah, this was a great story by Chris Stoker Walker.

Peter Kyle, the Minister for Science, Technology, and Innovation, has publicly said, or he told other journalists, that he loves using ChatGPT essentially.

He uses it to get the background on things, understand context, go deeper.

So that prompted Chris to submit a freedom of information request to access his ChatGPT log.

I think it's fair to say many people were flummox when, with some caveats, this was fulfilled.

And he received not the entire log, but any personal uses removed and just the sort of professional capacity left intact.

And it included things like asking what quantum and antimatter is, and quite entertainingly, what science podcasts he might like to appear on.

Just to dwell on that for a brief moment, ChatGPT, this generative AI large language model, suggested to the minister that he should go on Infinite Monkey Cage, which Inside Science team's quite miffed at, because actually there's no way he'd get on Infinite Monkey Cage.

He's not a comedian.

He should come on Inside Science instead.

Clearly.

But what's really interesting about this is how the government think ChatGPT should be used, or what role they think it plays, because to me, ChatGPT is something that you can just type in like a a Google search.

And there's no way the government would hand over everyone's Google search.

Yes, that was the first thing I asked.

Well, if you can FOI that, can you FOI a Google search?

And generally speaking, no, you can't.

And so I think that's the sort of concerning kernel in all of this: is that potentially the government is seeing ChatGPT as advice, providing advice like an advisor, because you can submit FOI requests on the advice given by WhatsApp and email, as opposed to just looking something up on Google or even in a dictionary, that's not FOIable.

And I really don't think large language models are at that stage yet.

They are essentially a search tool and one that can be quite inaccurate at times at that.

So that's the interesting bit.

Yes, large language models are still at that stage of suggesting that you put glue on pizza to glue the ingredients.

Yeah, indeed.

So maybe shouldn't be advising ministers.

That's us out of time.

Thank you so much, Penny Sasha, Managing Editor at New Scientist.

My pleasure.

Once again, that email address for your listener questions: bbcinside science at bbc.co.uk.

Till next time, bye from me.

You've been listening to BBC Inside Science with me, Marnie Chesterton.

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