Mini Episode: The Universe evolves too

with Liantsoa Finaritra Randrianjanahary

Hosted by Robbie Lees

In this week’s mini-episode, we chat with Liantsoa Finaritra Randrianjanahary who is a PhD candidate at the University of the Western Cape (UWC).

Liantsoa works in the field of cosmology which means he is researching the whole universe as one entity rather than focusing on the individual contents of the universe such as stars and galaxies.

We discuss his specific interest in the evolution of the universe and how he can determine some of the hidden secrets of the universe. Liantsoa’s work also involves the use of hydrogen measurements and even the density of the mysterious quantity known as dark matter.

This is a particularly hot field of research to be in during the modern era of astronomy with massive datasets being produced by the Square Kilometer Array (SKA), MeerKAT, and the Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) radio telescopes.

This week’s guest

Featured Image

This simulation of the underlying large-scale structure of the universe displays the dark matter web in blue and hotspots of galaxy formation in yellow. Image credit: Zarija Lukic/Lawrence Berkeley National Laboratory

Related Links


This mini episode was produced and hosted by Robbie Lees, an MSc student at the University of Cape Town.


Transcribed by Robbie Lees

Robbie: [00:00:00] Good day and welcome to this mini episode of The Cosmic Savannah. My name is Robbie and I will be your host for this mini episode. Firstly, a little bit about myself. So I’m a Masters student at the University of Cape town studying stellar astrophysics with my focus being on ultra compact binary objects.

Now ultra compact binary objects are just some of the most rare binary stars that we know of. And yet we haven’t detected that many of them in the Southern hemisphere. My project is to try and detect more of them in the Southern hemisphere. Today I will be interviewing Liantsoa, a PhD candidate at the University of the Western Cape.

Now Liantsoa sort of studies cosmology, which basically means that he’s studying the universe as one whole entity and not just individual parts of the universe. His aim is to unlock the secrets, at least some of them, of the evolution of the entire universe. That’s a pretty daunting task if you ask me. As you can imagine, this is all rather complex and so I’m going to explain some of the jargon and the terms that he uses just before we get into the interview.

Firstly, he talks about a nonlinear correction to the neutral hydrogen power spectrum. Now that all sounds very daunting. However, all I want you to take away from that is that basically Liantsoa is using hydrogen as a way to measure different parts of the universe and therefore study the evolution as a whole of the universe.

And via the corrections that he makes to his detections, he can infer certain information about the universe. Another thing that he mentions is dark matter. Now, dark matter is something we hear about a lot in sci-fi, but it’s actually a real thing. And all we know about dark matter is we can observe what effect it has on things like rotational curves.

Unfortunately, we don’t actually know yet what it is, which is why it’s still known as dark matter. So dark matter has effect on something called rotational curves, which Liantsoa mentioned, but I thought I’d just touch on it here as well. Rotational curves of something like a galaxy is simply a measure of the velocity of what’s rotating around the center of a galaxy at different distances from that center. To put it simply, matter is moving a lot faster than you would expect at the ages of galaxy due to the the contribution of dark matter.

Now baryonic matter is another term that Liantsoa mentions, which is just simply visible matter. Matter that we know what it is like atoms, different particles. We know what those are, those are baryons. Finally Linatsoa would just like me to mention that he has a speech impediment. However, this does not prevent him from giving us a great explanation of his fantastic work. Let’s enjoy the interview.

[00:02:28] [Intro music]

Robbie: [00:02:48] With us today we have Liantsoa, a PhD student from UWC who is working on cosmology. Hi Linatsoa.

Liantsoa: [00:02:45] Hi, Robbie,

Robbie: [00:02:48] So Liantsoa, tell me a little bit about what you work on.

Liantsoa: [00:02:52] I’m working on a cosmology. So I do nonlinear correction to the neutral hydrogen power spectrum. And from that I can infer the cosmological parameters and study the dark matter and dark energy and can tell how the universe is expanding and how it’s evolved.

Robbie: [00:03:23] That sounds all really interesting. When you talk about these cosmological parameters, could you explain what some of those are?

Liantsoa: [00:03:31] When we talk about cosmological parameters first, we have to know that we are working on the standard model of cosmology and for us cosmological parameters are like the density of the baryon in the universe, the density of the dark matter, the Hubble parameters which tell you how fast is the universe expanding, and the spectral index, which tells you about the shape of your power spectrum, and the Sigma eight, which is a fluctuation of the masses in the universe.

Basically, those are the main cosmological parameters, but there are more, but I’m focusing on these several that I just mentioned.

Robbie: [00:04:37] So it sounds to me like you’re studying what the basic contents of the universe are like dark matter, for instance. Um, could you expand a little bit perhaps on what dark matter is and how we have come about detecting it?

Liantsoa: [00:04:50] Dark matter is missing mass that does not interact, which is not interacting electromagnetically with the EM window, but it does, uh, interact gravitationally. So we can see the effect of dark matter by looking at the rotational curve. [It is] about 25 percent of the missing mass in the universe.

Robbie: [00:05:29] That’s great. Thank you for expanding on that. Um, it sounds all very interesting. Just, could you tell me why you came into this sort of topic? What sort of made you find this as your project for your PhD?

Liantsoa: [00:05:43] Oh, with the upcoming data sets and technology with MeerKAT and SKA and HIRAX, we want to do better forecast with more precision of how our universe is evolving and how it’s expanding. So I want to, to answer that question. And, I’m also interested in neutral hydrogen cosmology, which is one of the hot, the hot subject in cosmology and with that I do an intensity mapping technique in order to probe more volume and to have a better understanding of our current universe.

Robbie: [00:06:49] That does sound like an incredibly interesting topic, but I’m afraid that’s all we have time for today. Thank you so much for joining us today Liantsoa.

Liantsoa: [00:06:55] Thank you so much, Robbie.

[00:06:57] [Outro music]

Robbie: [00:07:06] That was Liantsoa talking to us about one of the most interesting fields I think there is at the moment: cosmology. I say that because I don’t think there’s a single field, which could be grander than the study of the entire universe, because that encompasses everything.

Some of the main points that Liantsoa brought up, were talking about cosmological parameters and how he can use those to infer certain things about how the universe evolves and expands.

He’s trying to study the basic contents of the universe as a way to unlock and uncover many of the hidden mysteries and secrets of the universe’s expansion and evolution. I myself, I’ve been to a few seminars and lectures on cosmology and it was quite astounding to me how much we actually don’t yet know about the universe, but how much we’ve been able to learn just in the last few years, just in recent times.

I think one of the most interesting points Liantsoa made there in that chat was how with the current and upcoming technology, there’s never been a better time, nor more interesting time to do cosmology. As with the vast amounts of data sets that new telescopes like MeerKAT and HIRAX are producing, we’re actually inundated with data, which can help us study the nature of the universe.

With people like Liantsoa working in this field, I’m sure we were able to uncover and learn lots more about the universe’s evolution, its expansion and its overall nature. Thank you again for a wonderful chat Liantsoa.

Thank you all for listening. And I hope that you have an absolutely fantastic day further.

Mini Episode: “From Hospitality to aspiring Astronomer”

with Bret Yotti

Hosted by Brandon Engelbrecht

In this week’s mini-episode of The Cosmic Savannah, we speak to Bret Yotti. Bret is a student and a lab assistant at the University of Cape Town (UCT) as well as a presenter at the Iziko Planetarium in Cape Town.

In our interview with Bret, we ask a common question known and feared by many: the “why” question. Why did he choose astronomy and what drove him towards this field of science?

We take a dive into Bret’s life before astronomy and find out how the journey has been since returning to the lecture halls.

We look at the work that Bret is currently doing at UCT, being a teaching assistant whilst being a student himself. Bret also talks about the work he is doing at the Iziko Planetarium and how he is helping to show visitors the mysteries of the Universe.

This weeks guest:

Featured image:
The Iziko Planetarium and Digital Dome is the most advanced digital planetarium on the African continent. This world class, multi-functional facility brings digital technology to Cape Town – creating a space of innovation and discovery – where art, science and entertainment meet.
The Iziko Planetarium and Digital Dome not only provides an immersive multi-sensory edutainment platform for artistic production – it is also used for cutting-edge scientific research to optimise South Africa’s eResearch and data visualisation capacity.
The Iziko Planetarium and Digital Dome makes virtual voyages of the universe possible, providing an unparalleled experience of animation and 360◦ cinema.  Explore the inner workings of the human body, or the intricacies of an atomic structure Visit the most advanced digital planetarium on the African continent. Credit: Iziko Planetarium:

Related Links:
University of Cape Town Astronomy Department:

Iziko Planetarium:

Featured image:

This mini-episode is produced and hosted by Brandon Engelbrecht (Centre for Radio Cosmology, University of the Western Cape)

Mini episode transcript

(By Brandon Engelbrecht)

Brandon: [00:00:00] Hello there and welcome to a mini-episode of The Cosmic Savannah, with me Brandon Engelbrecht. I know this is a little strange to hear my voice, but I would first like to thank our returning listeners for coming back, as well as welcome our new listeners to the show and secondly, I’d like to introduce myself.

So, as I said, my name is Brandon. I am a first-year PhD student at the University of the Western Cape currently trying to understand the mysteries of the Universe. But for now, I’m also a podcast host trainee. And the reason behind this is actually a new passion that I’ve developed over the years in science and that is science communication.

I’m very big on the idea of outreach and being able to give back to the community in terms of either explaining scientific phenomena and encouraging students to actually take STEM at the university level, which is the Science, Technology, Engineering and Mathematics programs.

However, the question I usually get is why did you do physics or why do you do astrophysics? And today on our show, we’ll actually have Mr Bret Yotti, currently, a teaching assistant at the University of Cape Town (UCT) explain to us his journey, as to why he did astrophysics at the University of Cape Town and what currently does his job entail? Also, we’ll ask him about his transition from being a student at the University of Cape Town to being a teaching assistant. As well as his job at the Iziko Planetarium where he does visual night tours of the night sky.

So sit back, relax and enjoy a mini episode of The Cosmic Savannah.

So hi, I’m with Bret Yotti and today we’ll be discussing a little bit about himself, what he does and why he’s chosen this path. Firstly, I would like to know from you Bret what do you do?

Bret: [00:01:52] So currently I’m finishing up an undergraduate degree at UCT. But my main job is working at UCT; with the teaching telescopes and the undergraduate students and I handle all of the undergraduate practicals involving the telescopes there and I maintain the teaching telescopes which I helped to install them. And then in my free time, I also work as an evening and weekend presenter at the Iziko Planetarium in Cape Town.

Brandon: [00:02:22] Oh, okay. That’s quite a bit. So you’re at the University of Cape Town and you’re a student, but you also, a technical assistant?

Bret: [00:02:33] Yeah, that’s right, I have several different ways of describing myself I guess. My payslips say a research assistant, I’m also called a head tutor for the observational techniques course, but yes, that’s right, I’m actually a student as well. I finished my astronomy undergraduate material last year. This year, I just have a few other credits to get before I graduate and because I’m working full time I decided to just do those on the side.

Brandon: [00:03:02] Oh okay so your studies have now taken a backseat to your paycheck?

Bret: [00:03:08] Exactly.

Brandon: [00:03:12] That’s what you said and of the two which one do you most prefer, being a student or being more of a research assistant slash head tutor?

Bret: [00:03:20] I definitely do not like being a student. I prefer the research assistants and the tutoring side of her time.

I enjoy teaching students. I enjoy working with them and seeing them discover new things. I love observing. Helping students to appreciate that the same way that I do makes me happy.

Brandon: [00:03:40] So in that sense, we share a similar trait there. I do like to see students, you know, when they smile, when they grasp some new knowledge and the light bulbs in their brain just start flickering and you know that you’ve got them.

Okay, I’ll come back to that. I’m also interested… you said you do some presentations at the Iziko Planetarium.

Bret: [00:04:01]. Yeah, that’s right. So the Planetarium was upgraded about four years ago where they made it into a digital Planetarium and shortly after that, I started working there as a presenter.

So that involves public groups coming in for entertainment and they see a short show 20 or 30 minutes and then I give them a tour of the night sky and I teach them some different things using the Planetarium software. They learn about galaxies, they learn about the Milky Way, they learn about constellations and the night sky from Cape Town.

And I’ve been doing that about three years.

Brandon: [00:04:37] That’s really cool. So you not only just like teach university students, you also try and take astro to a more broader audience. Cause I’m guessing, it’s not just students that go to the Planetarium. It’s also youngsters to the elderly folk as well.

Bret: [00:04:52] That’s right.

And there are different groups. So even with teaching first-year students astronomy, they at least have an interest in astronomy. So they know a lot of things already, what a star is, what a planet is. But at the Planetarium, you get all kinds of people and that’s one of the things I like about the Planetarium, is the questions they ask really gives you an insight to what the common person thinks about astronomy.

So they ask very interesting questions at the Planetarium.

Brandon: [00:05:22] I can imagine, okay so I got what you do, the why, so Bret why astros?

Bret: [00:05:28] Oh, well, I’ve done quite a bit in my life. So after high school, I worked in tourism and hospitality for three years, and then I worked in banking for six years and this is in the United States.

And then I went to Germany where I taught English as a foreign language for eight years and while I was there, I started not liking my job very much and wanted to do more.

So I started studying part-time remotely in Germany and got married while I was in Germany. My wife is from Cape Town, so we decided to move back and I transferred my credits to the University of Cape Town and started studying astronomy at UCT.

And when I looked at my life and tried to figure out what do I want to do? I looked at what interests me, what I do in my free time. And one of those things was reading about the Universe and stars and astronomy on the internet. So I wanted to pursue that further and now I’ve had the opportunity to do that.

Brandon: [00:06:23] Oh, you went very far hey, from tourism to a banker, to a teacher and then boom, you went into your passion. That’s cool and now you’re making your passion your literal job.

Bret: [00:06:32] Yeah, it’s nice to finally be able to get paid for doing something I enjoy, it’s an experience that I haven’t had until somewhat recently. That work could be something that you look forward to instead of something you do until the weekend comes.

Brandon: [00:06:48] And how was the transition from being, on one side? So as a teacher, you on one side of the classroom, and then as a student, you now on the completely other side of the classroom, how was that transition for you?

Bret: [00:07:02] That transition was a bit challenging but more challenging was the age difference, so going back and studying with 18-year-olds just coming out of matric to where I’m a peer with them, but I’m the same age as my lecturers.

So that was a big challenge to try and treat younger people as my peers and people of the same age as my superiors if that makes sense.

Brandon: [00:07:28] That makes sense. When I first met you too, I had to like take back. Cause it was like, oh, not a lecturer, a student.

Bret: [00:07:33] Yeah. And I think I was in my first year then, and I believe you were in honours or maybe third year at that time.

Brandon: [00:07:40] Yeah I was in honours for that one yeah.

Bret: [00:07:42] Yeah.

Brandon: [00:07:43] Alright, well, that is actually all the questions that I have at the moment. So thank you, Bret.

Bret: [00:07:48] Yeah. Thank you, Brandon, it’s been fun.

Brandon: [00:07:57] Well, that’s our interview with Bret from the University of Cape Town and the Iziko Planetarium. And hopefully, now we’ve explained why we do astronomy and astrophysics. And as Bret showed us in his journey, you’re never too late to start a new career or a new calling if you’re passionate about that.

And during the interview, something that really resonated with me was his passion for teaching and not just teaching to the classroom, but also teaching to the general audience. With his job at the Iziko Planetarium, Bret is able to explain the astrophysical phenomena and maybe even get people interested in doing astros or physics in the future.

So to me, that was really nice. I really enjoyed that and as you heard from Bret, it’s never too late to pursue your passion. So it is never too late to come into astros and on that note, I’d really like to thank Bret again for doing the interview and also would like to encourage our listeners for those in Cape Town and those planning on visiting Cape Town, post-Corona that is, to visit Bret at the Iziko Planetarium to watch one of the shows or to even meet Bret and ask him any questions you might have. I’m sure he wouldn’t mind answering them.

But on that note, I’d like to thank our listeners again for tuning in to this mini-episode of The Cosmic Savannah.

Goodbye for now.

Mini Episode: “But How Does Astronomy Benefit Humanity?!”

with Tshiamiso Makwela

Hosted by Andy Firth

In this week’s mini-episode of the The Cosmic Savannah, we are joined by University of Cape Town PhD candidate, Tshiamiso Makwela.

Tshiamiso works in the field of astronomy education research, and she explains how she tries to answer some very difficult questions.

What are the obstacles to learning? Is it simply ‘bad teachers’, or is there something deeper? What do the global trends suggest?

We also discuss the perceptions of astronomy in the broader community, as well as the world of possibilities that astronomy and astronomy education research have to offer society at large!

This week’s guest

Featured Image

An artist’s impression of ‘Measurement in Astronomy’; visualizing the difficulties related to quantifying distances or sizes of celestial objects which, unlike measurements performed on Earth, are not performed directly. Image Credit: NASA/JPL-Caltech

Related Links

Parsec Wikipedia Page:

Parsec, More Formally:

This episode is hosted and produced by Andy Firth

Andy Firth, M.Sc student based at the South African Astronomical Observatory


Andy: [00:00] Hello, and welcome to another mini-episode of The Cosmic Savannah. My name is Andy Firth, and I’m excited to be your guest-host today, taking a slight break from my work at the South African Astronomical Observatory – where I am currently doing research on the improvement of radio data, which will also be applied to surveys from the MeerKAT telescopes in the Karoo.

Our guest today is Tshiamiso Makwela. Tshiamiso is completing her PhD in Astronomy Education Research at the University of Cape Town, and has a background in astronomy and education, taking us down a very novel avenue in astronomy research. Today we will be discussing the perceptions of astronomy in the broader South African community – as well as what drove her to pursue a career that is often under-reported in astronomy.

When I first met Tshiamiso, I was in my final year as an undergrad student at UCT, and in getting the opportunity to do this interview, I was really excited to find out what the work she was so frequently fetching from one of the printers in the astronomy department at UCT was all about!

In our discussion and interview, we ran into interesting avenues such as the marriage of western and indigenous astronomy, and the impact concepts such as distances in astronomy as a predictor of future success. Especially with a word like ‘parsec’ being thrown around.

To fully grasp the idea of a parsec, I really do urge everyone to lookup the Wikipedia page on ‘parsecs’, as many astronomers have to do from time-to-time just as a reminder. It really does require a visual aid to drastically simplify an explanation in our brief episode alone. And trust me, that really does have the potential to become a word-salad.

For now, we can rest assured that a parsec is roughly equal to three-and-a-quarter light-years. And now, without another moment’s hesitation, let us hear from our guest – Tshiamiso Makwela.

[01:43] [Intro music]

Andy: [01:49] Hi welcome to The Cosmic Savannah, my guest today is Tshiamiso Makwela – hopefully I got that correct?

Tshiamiso: [01:54] Yes – you tried [laughter]

Andy: [01:56 ] Yes – I tried my very best – and she is going to be telling us about her research in Astronomy Education I believe, if my snooping online has done any good service?

Tshiamiso: [02:08] Oh wow you did well, you went online! That’s really good research, yeah!

Andy: [02:15 ] Thank you! So let me ask you the question that most people fear at a party, so: “Why did you decide to study Astronomy Education?

Tshiamiso: [02:26 ] Okay, so I really love astronomy, that’s the start of it, and I’ve always been interested in knowing more about astronomy and just understanding how the Universe works. But, every single time I mention to someone that “I actually love astronomy and I wanna do astronomy”, the question I got was: “But how does that help people? How does that help black people?” It’s sort of like doing something that’s typically useless. Then I got involved in doing some education research in my Honours, and then later on after I did my Masters I just thought: “Maybe I want to do a little bit of astronomy and education”, because for me that brings both the science and the people together; and that enables me to have some influence in the greater part of the education which focuses on people and in that way I am reaching out to people in some way. For me, that was like: “Science is cool, but if I can not necessarily have any form of relationship with this science for me it’s just [sigh].” So that’s why I was really so motivated to try and bring the sciences closer to the people, because it is done by people anyway.

Andy: [03:45] Were you saying, by that feeling you were having, you were feeling rather detached from some sort of application to human-kind in terms of the uses for astronomy?

Tshiamiso: [03:56 ] Yes, I call astronomy ‘the mother of all sciences”, literally because we grew up with astronomy; we have so many traditional and indigenous knowledge from our old people who will tell us all these things about stars, the Moon, the Sun, and that on its own is astronomy. But, we have used that to integrate what we know about the world. When we know when summer is, when winter is, our whole navigation system. The time – just knowing time! I feel like astronomy has influenced our life so much for us to let it be too far away from us at the same time. So I feel like the more advanced we got the more we lost touch with the actual essence of astronomy which we always had.

Andy: [04:46] That sparked a question I’ve always had, which is: “How do you marry two very different, or seemingly very different, studies of astronomy – such as the indigenous knowledge systems as well as this very westernised, highly-documented, form of astronomy?” Have you done any work in terms of how to marry those two spheres of knowledge?

Tshiamiso: [05:12] I haven’t, unfortunately – I really wish to do this one day. But I haven’t really done it. I just know a little bit about certain things in astronomy – like in indigenous language. Unfortunately, for me, I didn’t grow up in the rural areas because then I would have more rich knowledge in terms of that. Like the stories those people tell about the stars, and when you get into astronomy and you hear about these things and you hear they explain these things, it’s just like “Oh my goodness! They just missed it!” So, I hope one day – but I haven’t really done work on that.

Andy: [05:55] So, if I read correctly, your Masters was in astronomy education as well?

Tshiamiso: [06:05] Yes.

Andy: [06:07] What sort of burning question do you have at the moment, when it comes to Astronomy Education?

Tshiamiso: [06:10] At the moment I am actually looking at students, not the teachers themselves. I am looking at university students and how they interact with astronomy content. I am looking at first-year students coming into the university. And we have found out that (I did a study when I was starting my PhD) a lot of students struggle with understanding sizes and distances. Sizes and distances are also two important things in astronomy, because how well you do in those determines how well you actually do overall in the course. How well you understand the content going forward. In our sample in 2018, about 30% of our students couldn’t understand sizes and distances – they were not getting it right. And another result was done in 2014, and we got similar results with them. But, there was another group of teachers and middle-school students (so this is grade 9, grade 10 students) in Norway – and our results were pretty similar to theirs. So, for us it was not about poor teaching – because it’s really easy for us to default to “it was just poor teaching”. But, in this case, we realise it is not just poor teaching. So poor teaching may be a factor, but it is not just poor teaching; and I just thought maybe there’s a deeper issue – like with understanding distances. That’s when I decided to look at distances and how we comprehend distances.

Andy: [08:13] Okay! I think our time is up. Tshiamiso, thank you very much for your time and for explaining the intricacies of trying to convey the concept of distances to learners.

Tshiamiso: [08:29] Thank you very much for having me! We haven’t found the answers of how we can do that for learners, but we are still on the journey! [laughter]

Andy: [08:44] Hopefully running and not crawling! [laughter]

Tshiamiso: [08:47] Yes! We are not crawling anymore, but crawling was very important for us to understand this.

[08:51] [Outro Music]

Andy: [08:57] And what inspirational words to end off our interview with Tshiamiso, a PhD candidate in Astronomy Education at the University of Cape Town. Today we learned that knowledge extends much further than what is said in the classroom, and that factors such as intuitive understanding of distances, learned in youth, play a pivotal role in understanding of abstract concepts in later life.

A question which was often asked my way was ‘how is astronomy useful to humanity’ and it really goes to show that research can have very many unintended benefits for humanity. And Tshiamiso touched on this too, that through research we have the opportunity to gather and collect indigenous knowledge of astronomy, which may serve as a great unifier of the human experience – we all looked up at the sky in wonder.

And that’s it for this week’s episode of the mini- Cosmic Savannah! I’ve been your very happy host Andy Firth, thank you to our guess Tshiamiso Makwela and to you for sharing this very exciting episode with me. Until next time, stay safe everyone!