Mysterious einsteinium spills its secrets

Host: Shamini Bundell

Welcome back to the Nature Podcast. This week, probing the properties of einsteinium…

Host: Nick Petrić Howe

And getting a computer to calculate new mathematical conjectures. I’m Nick Petrić Howe.

Host: Shamini Bundell

And I’m Shamini Bundell.

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Host: Shamini Bundell

To start off the show, I’d just like to say, it’s great to have Nick Petrić Howe on for the first time.

Host: Nick Petrić Howe

That’s right. I’ve changed my name to match my wife’s surname, and only three years after we actually got married.

Host: Shamini Bundell

Well, better late than never. So, back to the pod, what have we got first this week?

Host: Nick Petrić Howe

Well, this week, I’ve been talking to a researcher who’s into heavy metal.

Interviewee: Rebecca Abergel

So, my field of interest is the coordination and biological chemistry of heavy elements.

Interviewer: Nick Petrić Howe

This is Rebecca Abergel, a chemist from the University of California, Berkeley and the Lawrence Berkeley National Lab, and when she says heavy elements, she means it. She focuses on the actinides, the elements that hang out right at the bottom of the periodic table.

Interviewee: Rebecca Abergel

So, when we look at the actinide series, there are over a dozen elements, but what we’re really interested in are elements beyond plutonium. So, the transplutonium series, they’re not very much explored.

Interviewer: Nick Petrić Howe

The reason we don’t know a lot about these elements is because they don’t occur naturally. They have to be man-made through highly intense processes. In fact, they were first discovered during the nuclear test of the Manhattan Project, so it’s hard to get a lot of them. Also, they’re all radioactive so even if you can get some, you can’t keep hold of it for very long before it decays. But this week in Nature, Rebecca has been trying to close this knowledge gap by examining one of the transplutonium elements – einsteinium. For einsteinium, the issue of radioactive decay and scarcity was amplified. This is a particularly heavy transplutonium element. Rebecca was only able to get a hold of a few hundred nanograms and even then, there was quite a lot of its neighbouring element in the sample as it’s so difficult to purify. All the while, it was rapidly disappearing.

Interviewee: Rebecca Abergel

So, all in all, it means that you have to be very precise, very quick, well prepared, and make sure everybody is safe.

Interviewer: Nick Petrić Howe

It also meant that some of the typical ways that chemists examine elements weren’t possible. But Rebecca was able to access a particularly precise kind of X-ray produced by a particle accelerator, which allowed her to probe einsteinium and find out how it bonds to other atoms.

Interviewee: Rebecca Abergel

We were able to determine a bond distance for einsteinium, and that means the length between einsteinium and the coordinating atoms, so an atom that is binding or attached to the metal, and that bond length was shorter than what we expected.

Interviewer: Nick Petrić Howe

This wasn’t the only surprise, though, as Rebecca also investigated how einsteinium reacted to light.

Interviewee: Rebecca Abergel

When we shine light on our sample, it absorbs light and that gets transferred through various processes into other light emitted from the complex, and what we observed is that we could shift the luminescence emission from the einsteinium in a way that was different from the way we shift the luminescence from other metals. And so, again, it behaved differently from what we expected and so that tells us that there’s something special about einsteinium in that it doesn’t behave as we expected.

Interviewer: Nick Petrić Howe

Einsteinium seems quite different from what you’d expect given what we know of its lighter neighbours. Rebecca didn’t want to speculate too much on why this might be, but it could be down to its electrons.

Interviewee: Rebecca Abergel

It has to do with the interactions between the electrons themselves and the constituents of the nucleus in the einsteinium atom. So, how the electrons are distributed around the nucleus in einsteinium and how they spin around, really. That will affect how the metal will bind to other atoms in other molecules. So, what we’re trying to understand now is why did we observe this and what is the phenomenon that drives this difference.

Interviewer: Nick Petrić Howe

Whatever it is that is driving einsteinium’s oddity, it’s unusual properties could be a sign of things to come in the periodic table. Einsteinium is the heaviest element to have undergone such analyses, and it could be that heavier elements still display similar weirdness. We really don’t know, but Rebecca’s research may lay the groundwork for finding out.

Interviewee: Rebecca Abergel

We’re really treading the path for doing more of this work. If we have access to this material again, we have access to all these different facilities, other folks may have access to other facilities where we could really start building upon this and getting more data so that, yes, at some point maybe we’ll have a better understanding of how these elements behave, and that will help us go back to look at the earlier actinides and maybe revisit some of the theories that we’ve established to explain their chemical behaviour. Even though this seems really just a fundamental result, an element that may not have too many applications, we may be able to go back in the series and start understanding some other properties that didn’t necessarily fit the expectations or the theory properly.

Interviewer: Nick Petrić Howe

That was Rebecca Abergel. To learn more about einsteinium and its peculiar properties, make sure you check out the show notes where there’ll be a link to Rebecca’s paper.

Host: Shamini Bundell

Some listeners may already be aware but this is just a short PSA that Coronapod, which would have normally been around now, is a separate show again. Make sure you keep an eye on your podcast feed for that later this week.

Host: Nick Petrić Howe

Back to the current show and, coming up, we’ll be talking about how a computer is coming up with new ways to calculate famous numbers. Right now, though, Dan Fox is here with the Research Highlights.

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Dan Fox

An atmospheric mystery is afoot as, despite being banned, three ozone-depleting chemicals have been found by scientists in the Earth’s atmosphere. The 1987 Montreal Protocol limits production of dangerous chemicals that can gnaw away at the Earth’s protective ozone layer. But researchers analysing air samples gathered around the world have found such a compound, the catchily named HCFC-132b. Analysis of archived samples revealed the compound first showed up around two decades ago. Since then, levels of the chemical, which seems to be coming from factories in East Asia, have trended upwards. The team also detected two other compounds, however none of the three have any known industrial use, making their source puzzling. Read more about that research in the Proceedings of the National Academy of Sciences of the United States of America.

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Dan Fox

Scientists investigating the rise of ride-sharing services in the US have found that they may not have as positive an impact on transportation as once hoped. Ride-sharing giants Uber and Lyft began operating in the United States in 2010 and 2012, respectively, and promote car-sharing as a sustainable way to increase urban mobility. But researchers trying to quantify the services’ impact by analysing transport data from across the US found ride-sharing barely had an effect on private car ownership. However, the use of public transport declined by almost 9%. They also saw that traffic jams become more frequent and intense in cities where car-sharing services were available. They noted that while the idea of sharing remains a promising solution to urban transport challenges, translating that potential into success is a more complex proposition. Take a ride over to Nature Sustainability to read that research in full.

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Host: Shamini Bundell

Next up on the show, Nature’s Davide Castelvecchi has been finding out about a new method to calculate some well-known numbers.

Interviewer: Davide Castelvecchi

The field of mathematics is littered with numbers that are so important that they are known by a symbol or a name. You certainly learnt about one of the most famous ones at school – pi – a number that begins with 3.14 before its decimals stretch out forever. Physicists call such numbers fundamental constants, and many of them share pi’s infinite length. These numbers play key roles in fields as diverse as calculus, quantum mechanics and statistics. But there’s still a lot that we don’t understand about them despite some of them being studied since the time of the ancient Greeks. Now, though, a very modern method might help to speed up how quickly we can learn things about them.

Interviewee: Ido Kaminer

We have those constants that have an infinite number of digits representing them. Where does it end? What is really the internal structure that helps us understand what’s that number coming from?

Interviewer: Davide Castelvecchi

This is Ido Kaminer, a physicist from the Technion—Israel Institute of Technology, who’s interested in finding out more about fundamental constants and formulas for calculating them.

Interviewee: Ido Kaminer

I always thought that there’s so much data in them that there has to be a way to apply computers to use this data to convert it into new formulas.

Interviewer: Davide Castelvecchi

This week in Nature, Ido and his colleagues have shown a way to do just that. They’ve created artificial intelligence algorithms that can probe these fundamental constants and come up with new formulas for calculating them. They call the system the Ramanujan Machine after Srinivasa Ramanujan, a mathematician who was active in the early 1900s and was famous for coming up with new formulas in his dreams. To put the system through its paces, the team focused first on that well-known fundamental constant – pi. They delved into the history books to look at the work of another famous mathematician, Carl Friedrich Gauss. He discovered some famous formulas for calculating pi known as continued fractions.

Interviewee: Ido Kaminer

Apparently, Gauss, known as the prince of mathematics, had several such continued fractions for pi, and then we thought, ‘Well, he has a couple of them so what’s the chance that those are all the formulas that are possible? There has to be more.’ So, we thought, ‘Okay, let’s try to develop an algorithm that will be able to on the one side also discover the results that Gauss already found – we can think about it as a sanity check – and on the other side, also discover new ones if they exist.’

Interviewer: Davide Castelvecchi

The Ramanujan Machine starts from one well-known formula for calculating the digits of pi. From those digits, in then tries to guess a new formula that does the same job just as well, at least for the first few thousand digits. But will the new formula continue to produce the correct digits forever? All the computer can do is give a good guess or what mathematicians call a conjecture. Of course, no conceivable computer could calculate an infinite number of digits to show that the conjecture is 100% correct, so it’s then up to humans to prove that the formula gives the correct value for pi. In the end, the computer did rediscover the formulas Gauss had found for pi around 200 years ago, but also it came up with new ones that hadn’t been seen before.

Interviewee: Ido Kaminer

This was really a moment. How can I explain how exciting it was? After a very long time searching for different ideas and trying different things that all failed, seeing the first time that the computer gave us a result that didn’t seem to match anything that Gauss did or anyone else since then. I remember writing it on a piece of paper, trying to calculate it yourself quickly to make sure it’s real? It was really a moment that’s hard to forget.

Interviewer: Davide Castelvecchi

But pi was just the beginning.

Interviewee: Ido Kaminer

For pi, we actually know quite a lot already. Finding new formulas for it may be useful if you want to calculate faster, more digits, but I think where the algorithm is really more important is when we look into new constants for which there are still many open questions.

Interviewer: Davide Castelvecchi

Ido has also been using the system to come up with conjectures for calculating other less understood numbers. One of them is the Catalan constant, a number so mysterious mathematicians can’t even decide if it’s a rational or an irrational number. Currently, the Ramanujan Machine can only generate these formulas called continued fractions, but Ido hopes that it could be improved upon to create other types of formulas that are important for other areas of mathematics. These could point mathematicians towards connections between branches of maths that people did not suspect existed. But with the new machine’s ability to find conjectures, does it risk putting human mathematicians out of a job? Ido doesn’t think so. Coming up with new conjectures complements their work, providing new avenues for researchers to follow.

Interviewee: Ido Kaminer

For our case, when we bring conjectures, I think it’s completely not in a competitive place because it actually produces new directions, new options for things to prove, and that actually happened for us. The first result we found, we went out to the wider community and we published those results online and indeed, mathematicians proposed ideas for how to prove the results we found and indeed proved them, and that also got us to try and develop more complex algorithms that will find more complex results, and by now there are open questions that mathematicians can follow on. This is, for us, the most exciting part because it can create new leads for new mathematics. I don’t think it replaces anyone in that sense, only the opposite.

Host: Shamini Bundell

That was Ido Kaminer from the Technion—Israel Institute of Technology. You can find a link to his paper in the show notes.

Interviewer: Nick Petrić Howe

Finally on the show, it’s time for the weekly Briefing chat where we discuss a couple of articles that have been highlighted in the Nature Briefing. Shamini, what have you found for us to discuss this time?

Host: Shamini Bundell

So, I’m slightly cheating this week, and what I wanted to talk to you about is a topic that I’ve already been researching because I’ve made a film about it, which is up on our YouTube channel, and it’s a sort of mystery from 1959. It’s kind of a tragic story where nine students went off on a kind of cross-country skiing/hiking trip in the Ural Mountains in Russia, and were later found dead in mysterious circumstances.

Interviewer: Nick Petrić Howe

Oh, okay, this sounds very, yeah, intriguing, but I know next to nothing about it, so what was particularly mysterious about how they were found? Surely people die on hiking trips all the time?

Host: Shamini Bundell

So, obviously, sort of cross-country hiking and skiing can be quite perilous. This is a really harsh landscape miles from anywhere, freezing temperatures. There might be blizzards, high winds, frozen rivers, all sorts of things. These people were all very experienced and sort of well prepared for all this, and the real mystery comes from the way that they were found. So, they essentially didn’t report back in at the end of this trip and rescue teams were sent out and they eventually found their tent, and the tent had been apparently just abandoned in the middle of the night, cut open from the inside, and the hikers had left the tent, in most cases without shoes, certainly without their full sort of protective gear and multiple layers, and doing this in such horrific, freezing temperatures, they would had to have had a pretty good reason. And ultimately, they died of hypothermia due to the temperature but in addition to this, some of them had unusual injuries on their bodies, so broken bones. And actually because it was kind of inexplicable and mysterious, there are pages and pages of possible sort of clues and hints and things that people have tried to explain about the way they were found, what they had on them, what they were wearing, what they left in the tent, where exactly they were, just mountains of stuff of people trying to sort of piece this incident, this night, together when of course no one survived to be able to tell what actually happened.

Interviewer: Nick Petrić Howe

Okay, so this sounds hugely mysterious, as you said, because it sounds like they cut their way out of the tent, they were in a hurry, I’m guessing, and then their bodies were found away from it in strange circumstances, so what have been the theories to explain this?

Host: Shamini Bundell

Well, this has been over 60 years now since this incident, so there’s been plenty of time for people to debate various theories. There was a lot of distrust from the time, I think particularly from the families, of the way the authorities handled it, and that led to a lot of feelings that there may have been some sort of cover up, maybe some sort of Soviet scientific experimentation going on in the area or something like that. Slightly more far-fetched theories maybe that they were attacked by a yeti, looking at a blurry photo from one of their cameras and being like, ‘Could this be a yeti? We don’t know.’ And that it was some sort of force of nature. The idea that it was an avalanche, that they were sort of hit by an avalanche, has been a big one for a long time, but there have always been reasons why that doesn’t seem to match the evidence, why an avalanche doesn’t seem to fit with a lot of things.

Interviewer: Nick Petrić Howe

Right, okay, but I’m guessing because you made that video about it, we’ve got some sort of new insight even though it’s been 60 years now since?

Host: Shamini Bundell

Yes, new science. So, yeah, there’s been a new paper which is focusing specifically on the avalanche theory, and this is by some scientists who in particular study snow and the sort of science of snow, how it moves, how it works and how avalanches occur, and they’ve been looking at the possibility that it was a small slab avalanche, which is a particular kind of quite dangerous avalanche, and they’ve been basically trying to show that that does fit with all the evidence and sort of look at the reasons why people think it wasn’t that and say, ‘Oh, well, here’s how we can explain away sort of the counterarguments and explain what you see and show that an avalanche could have explained at least the sort of basics of what happened to the tent, how they got injured and why they initially left the tent.’

Interviewer: Nick Petrić Howe

Right, well, I’m no snow scientist, but surely there would have been some sort of signs of an avalanche if that had been what caused these mysterious deaths?

Host: Shamini Bundell

It sounds like the possibility that this paper is putting forward is a sort of quite unusual situation, which could explain why, first off, a bunch of people who were quite familiar with avalanches could have sort of found themselves accidentally hit by one, explains why a bunch of rescuers who know what avalanches look like didn’t seem to see one, and might explain why there hasn’t been an avalanche there since that anyone’s recorded, and it’s all to do with sort of quite complex details about the typography of the precise slope where they pitched their tent that night, and the speed of the winds, the types of snow in different layers. But this analysis and the authors are quite keen that they’re not sort of hiding this away. They’re sort of putting this out there and saying, ‘Look, here’s our data, here’s why we think this was possible, a sort of small but ultimately deadly avalanche on a relatively shallow slope,’ and they’re putting that out there as a possible explanation for these deaths.

Interviewer: Nick Petrić Howe

Right, so this sort of small unusual avalanche might have caused it, but then you said they had injuries and things on them. Were they hit by the avalanche? How does it explain some aspects of that?

Host: Shamini Bundell

Yeah, so, I mean, people do get injured in avalanches, but usually they’ve been skiing and they’re sort of tumbling down a hill and the types of injuries that they have are quite different. In this case, what the sort of paper hypothesises is that the hikers were sleeping on a sort of quite hard, flat surface when a large slab of snow felt straight down on top of them, which is not usually how avalanches go, and could explain like a crushed rib or fractured skull. We think of snow as nice and soft and fluffy but absolutely in the wrong situation it can be very heavy and very dangerous.

Interviewer: Nick Petrić Howe

I feel like I need some sort of visual to help me understand this properly, but it sounds like we’ve got a video for it.

Host: Shamini Bundell

It does, you’re so good at plugging my videos. I love it, Nick, thank you. Yes, you should go and watch. No, it is quite useful. So, they’ve got some models there and actually, the really fascinating thing when I was making the video is that most of the students who went out on this trip had cameras with them, so we have so many photos, not, obviously, of the sort of incident, nothing from that night, but of them sort of laughing and having a great time sort of skiing through blizzards and putting up their tent in these sort of harsh circumstances, and it’s really quite haunting to see and to know that we’ll never really know the sort of full story of what happened and actually, even after 60 years, this mystery is going to last.

Interviewer: Nick Petrić Howe

Because as you said, they haven’t firmly solved this one way or another, they’re just sort of putting this out as their theory of what might have happened and might explain some of this.

Host: Shamini Bundell

Yeah, they don’t claim to have solved it. I’m sure lots of people will think that this is a definitive solution. A lot of people will think their own different theory is the definitive solution. But they don’t claim to be proving anything, they just want to show that it was plausible, and they’ve put forward a pretty convincing case. So, yeah, people will have to go and look for themselves.

Interviewer: Nick Petrić Howe

Well, it certainly sounds like a very intriguing story, and I’ll be curious to see the video, which is on our YouTube channel. But for my story this week, I’ve also been looking at new data that may disprove old theories, although they’re not quite as old, and I’ve been looking at the life on Venus via phosphine thing that you might have seen in the past few months.

Host: Shamini Bundell

Yeah, so I feel like I remember this. This was a big news story because obviously we’re always looking for life here, there and everywhere, and was this a sign of life? Was this a hint of life? Did we think that there was life on Venus?

Interviewer: Nick Petrić Howe

Yeah, so phosphine was a gas that was detected in Venus’ atmosphere, and phosphine on Earth is produced by microbes or by industrial applications, and there didn’t seem to be a good explanation of why it might occur in the atmosphere in Venus, so some scientists suggested that it could possibly be a hint of life on Venus, maybe some sort of microbial life floating about in the clouds.

Host: Shamini Bundell

Oh, wow, okay, awesome. Yeah, so, if there’s phosphine gas there, could there be life there? We’re just detecting the sort of side product of it. And so, you’ve got an update. Is it an exciting update? Aliens on Venus, please?

Interviewer: Nick Petrić Howe

I don’t think we can say aliens on Venus yet, but we can’t also definitively say not aliens on Venus yet. But this seems to be a very strong challenge to the claim that there might be life on Venus. Well, this is really just about phosphine which so far is the only indication that there could be life on Venus, and so this counter-claim is the biggest challenge so far to the fact that phosphine was detected in the atmosphere. So, essentially, what this is about is scientists have re-examined the data that originally showed phosphine and have said actually, it could just be sulfur dioxide, which is quite a common gas in Venus’ atmosphere and so wouldn’t be a sign of life.

Host: Shamini Bundell

Oh, that sounds very disappointing, but surely we can tell the difference between phosphine and sulfur dioxide?

Interviewer: Nick Petrić Howe

Yes, and the original researchers did do some work to try and do that, and they used two different telescopes from two different locations on Earth to sort of map out this data and look at the absorbance because sulfur dioxide and phosphine, they have very similar absorbance wavelengths, so when you look at them through telescopes they look kind of similar. But they looked with another telescope as well to sort of try and figure out if it was sulfur dioxide or phosphine, and the data from that telescope seemed to suggest that actually, no, it wasn’t sulfur dioxide and so therefore it should be phosphine. But now, researchers have re-examined that data and it looks like it may have just been processed incorrectly from the observatory.

Host: Shamini Bundell

Oh, so this isn’t just the sort of latest update. It could have actually been that there was a mistake in that sort of original paper?

Interviewer: Nick Petrić Howe

Yeah, it could be that some of the data just wasn’t processed properly and that’s what led to this result, and the researchers who have looked at it in this latest work have suggested that all signs point to sulfur dioxide, which, as I said, is quite common in Venus’ atmosphere so wouldn’t be a sign of life.

Host: Shamini Bundell

Well, slightly disappointing updates there then, but glad that they’ve been able to look at the data in more detail and potentially remove any errors. And they can keep looking for other signs of life. I hold out hope.

Interviewer: Nick Petrić Howe

Indeed, well, maybe there’ll be some signs in the future. Who knows? But I think that’s all we’ve got time for on the Briefing chat this week. Thanks for talking to me, Shamini, and listeners, if you’d like to know more about all the stories we discussed, you can find links to them in the show notes. And if you want even more stories like this but delivered straight to your inbox then make sure to sign up to the Nature Briefing. There’ll be a link in the show notes where you can do just that.

Host: Shamini Bundell

And don’t forget, a link to our YouTube channel as well and the Dyatlov Pass video as well as all the other wonderful mini documentaries that we make.

Interviewer: Nick Petrić Howe

That’s all for this week from us, but don’t forget that Coronapod will be coming out later this week. I’m Nick Petrić Howe.

Host: Shamini Bundell

And I’m Shamini Bundell. Thanks for listening.