Telescopes Through Time

We take a look at the future of telescopes...
08 September 2020
Presented by Adam Murphy, Chris Smith
Production by Adam Murphy.


A telescope with a sepia filter over the image


This week, the story of how humankind has gazed into space, from the first basic telescopes to what gravitational waves are now revealing about the workings of black holes. Plus, in the news, evidence that people are catching COVID again, what’s the risk of coronavirus infection on an aeroplane, and bee venom to treat breast cancer...

In this episode

A stylised coronavirus particle next to a woman wearing a facemask.

00:56 - COVID reinfection is possible

The first cases of reinfection of coronavirus have emerged

COVID reinfection is possible
Jeremy Rossman, University of Kent

Doctors in Hong Kong have reported the first confirmed case of someone being re-infected with the new coronavirus. Until now it’s been an open question whether or not getting COVID and then recovering makes you immune. But this case - along with others now surfacing including a man in the US - suggests otherwise. Phil Sansom asked virologist Jeremy Rossman for his thoughts…

Jeremy - What we've seen recently from Hong Kong, and then some data in the U.S. is when the person was initially infected, they actually sequenced the virus. And then when the person was sick again, they sequenced the virus again. And by comparing the genome of those two virus samples, they were able to say that, in fact, this was not one long infection, but was an infection with two different variants of COVID-19. So we can now definitively say that in fact, reinfection is possible,

Phil - Oh God. Well, who are our unlucky winners in this horrible situation?

Jeremy - I don't actually know. That's an interesting question. I don't actually know.

Phil - I actually do, I'll give it to you. So in Hong Kong, it was a 33 year old man who got his first coronavirus in March they tested him. And then he got it again in August. And then there's this other person in Nevada. Who's a 25 year old man, but the Hong Kong guy actually didn't have symptoms the second time. But the Nevada guy got them way worse.

Jeremy - Yeah, we are very curious to know what happens in the reinfection, because this has very large implications for what happens if somebody is vaccinated. Vaccines provide a level of immunity, but some vaccines don't perfectly prevent infection. And so if somebody is reinfected and has a lower disease severity, that's a pretty good indication that vaccines might also lower disease severity. Whereas if you have a worse disease, then we might have some concerns. And we don't know if this is the case yet. From the two reinfections that we know so far, we've seen very different phenomena. In one, we've seen much more mild reinfection and in the other, we've seen a more serious reinfection,

Phil - I'm kind of impressed that you managed to find a positive thing that we can learn out of this. Because isn't this reinfection something that people have been really, really worried about?

Jeremy - It is. But we have to take this with a grain of salt, because we are looking at a tremendous number, millions of cases of coronavirus worldwide. And we are looking at the first two known cases of reinfection. So yes, this says that reinfection can occur, but this may be a vanishingly small number. This may only occur after a certain amount of time. We don't necessarily have to worry.

Phil - Do you think it'll have to do with how your immune system reacts the first time round?

Jeremy - Certainly. What we're looking at is the development of immune memory. There are two main ways in which you get immune memory. Antibodies, or B cells and T cells, and both of these can be very effective and can work together to help protect you. But the real question is how effective these immune responses are at preventing infection. So I'll give you the example of antibodies. Sometimes the antibodies aren't active enough, they don't prevent infection. Maybe they just lower disease severity. The other aspect is that just because you've formed the immune memory, this tends to decay over time. And we've seen some evidence of this. There are a lot of variables here, and we're really just starting to get the answers. And there's still a lot of data that we don't know yet.

Globe wearing a facemask

Coronavirus spread on planes
Julian Tang, University of Leicester

Recently, all 193 travellers returning on a flight back to the UK from Zante were told to quarantine themselves for a fortnight after 16 people tested positive for coronavirus. TUI, the operator, are urgently investigating practices on the flight that might have contributed to the outbreak. So how safe are aeroplanes? The World Health Organisation suggests that transmission is limited to a couple of rows either side of an infected case. The University of Leicester’s Julian Tang specialises in the airborne spread of viral infections...

Julian - The highest risk, looking at the airflow dynamics of exhaled breath, is when they're directly beside you. If they're in front of you and behind you, the deflection effect of the seats will actually, probably, deflect a lot of the aerosol upwards, where the aeroplane ventilation - which is very efficient - can actually remove that exhaled aerosol. And the ventilation in planes is typically 20 to 30 air changes per hour, which means they can remove and replace the whole of the cabin air volume within two to three minutes, and remove that airborne virus away very quickly. But if you can smell your neighbour's garlic breath or alcohol after their meal, you then have enough air to transport airborne virus within that short distance between you before the ventilation can actually whisk it away.

Chris - Where does the air actually flow in an aircraft? Does it come from above and disappear through the floor, or does it sort of mix up like a giant washing machine?

Julian - Essentially this is a very strong airflow, they're counter rotating currents coming from above your head and drawn down underneath your feet. Different planes have slightly different flow patterns, but generally they are designed to prevent longitudinal flow of any airborne contaminant down the length of the plane. So they're like a series of counter rotating flows all the way down the plane to limit that forward-backward transmission. Unfortunately they're probably not efficient at the close range conversational contact distance that you have talking to your neighbour to whisk that air away sufficiently quickly.

Chris - And of course there's the whole issue of the airport itself, isn't there? Because while the aeroplane may well have these measures in place, there isn't a similar sort of thing in the airport building, where you might have people lingering together for prolonged periods of time sharing air.

Julian - Exactly. So it's very hard to actually decide where a person who's infected acquired the infection from, particularly if you're two hours pre-boarding and one to two hours de-planing to pick up your luggage, you're standing beside somebody at the Customs security gates, or picking up your luggage that may actually transmit the infection to you. And when they test you three to five days later, it's very hard to tell where you actually got that infection from because of that close temporal proximity of those potential contacts.

Chris - So in your view then - given that planes have all these measures in place but, say, trains and buses don't - do you think you're safer on a plane than you are on the train to London?

Julian - I think if everybody is masking, given a similar baseline, I think the plane would be a safer place. The only disadvantage with a plane is that you have 200 to 300 passengers in a very, very tight space, whereas on a train or a bus you might be able to spread yourselves out a bit more, plus you can open windows for example. So the plane is really a captive audience of high density; you rely a lot on the mechanical ventilation, which has been filtered, which is not on trains or buses typically; and you rely on your fellow passengers to keep their masks on to reduce transmission in that very tight, confined area.

Chris - Of course it's easy to say but hard to do, isn't it? If you need to eat, you need to drink, you need to do various things, you might not be able to maintain a hundred percent masking. Especially if you're in a long flight.

Julian - Exactly. And that's why, unfortunately, outbreaks like this are probably inevitable. When you've got 100 million to a billion passengers travelling by air over a course of a year, you may unfortunately see a few of these clusters, especially with this virus which seems to be much more transmissible; and mutations in the virus spike protein suggest it’s becoming more transmissible, adapting to the human population, going forward. But hopefully if you can maybe stagger the eating times amongst the passengers so some of them can keep their masks on while others are eating, you can reduce this transmission rate further.

Chris - Are there any tips that you could offer to our listeners so that if they are destined to take a flight in the near future, they can minimise any risks that might come from their trip abroad?

Julian - One thing I've been thinking about doing is that, if the main risk has been taking the mask off to eat or to have refreshment, if you can try and time that when your neighbours - your immediate neighbours left and right of you - are not doing the same, that's probably the thing I would consider doing, because they're the most risk in terms of being a source of the virus. The air hostesses do collect the trays on a regular basis, so they may have to stagger the distribution of the food trays, refreshment trays, at different times so passengers can actually stagger their eating; but I don't know how easy that is to do, particularly if their flight is not that long and they have to dish out the refreshment in a timely manner. Also if you can not talk to your neighbour, not talk when you're waiting at the toilet - be antisocial, because talking is actually a risk - that would minimise your exposure and the exposure to other passengers from your breath.

a picture of a medical swab

12:04 - Improving COVID testing

How can you catch all the false negatives?

Improving COVID testing
Ravi Gupta, University of Cambridge

One big problem when testing people for COVID-19 is false negative test results. This is where a person is tested for coronavirus infection and told they are negative when in reality they really are infected: one study found that this might be the case in more than half of patients. It probably happens because swabs collected from the nose and throat might not pick detectable amounts of the virus, particularly at the early or late stages of the infection. But there are ways of making sure that these people don’t slip through the net. Adam Murphy spoke to Ravi Gupta, form the University of Cambridge, who has been testing one of them…

Ravi - Yes. Well, it all stemmed from experiences we had very early in the epidemic, during the first wave in the hospital where I work at Addenbrooke's, where significant numbers of high likelihood patients were testing negative on their first swab and then being admitted to either intensive care or requiring oxygen. So these were clearly people who had a high probability of having the infection, but were coming up negative. And it just got me thinking that we really need to have a way of making a firm diagnosis. The reasons for having a negative test are multiple. One may be inadequate swapping technique or more likely is that during the later phases of illness, when you progress to moderate or severe disease, the virus actually is replicating or dividing or making copies of itself, not just up in the nose and throat, but actually down in the lungs, where it causes more severe inflammation, and that's why people get more sick.

So this study does not call into question what's happening in screening strategies. So if you screen negative, then you're not infectious. So I really want to make sure that people don't come away from this thinking that a negative test out in the community means you could still have COVID. Our study was really looking at hospitalised patients where they have virus production lower down towards their lungs. So we started asking ourselves, well, how else can you measure exposure to the virus or get a diagnosis? And of course your antibody response, your immune response, is a marker for infection. So we started looking at antibodies for coronavirus, and we were able to use a selected rapid finger prick test to tell us whether somebody had antibodies or not. And when we put the antibody test together with the swab test that looks for genetic material, we were able to come up with a highly sensitive and specific test for patients coming to hospital, so that we could get up to a hundred percent diagnoses.

Adam - Is that what you can get up to then, 100%?

Ravi - Yes, so in this small study, it was a relatively small number. It was only about 50 patients that we were able to do this in, because you needed to have stored serum, you needed to have a diagnosis at the front door and you needed to have had the correct swab taken. So you can identify everybody who has coronavirus using the PCR, combined with an antibody test. Which makes sense, because if you look at the way that the virus goes up and down and the way the antibodies come up and down, there's a very significant overlap between the two. So you should catch everybody using the two tests together.

Adam - And then what about the other side? False positives. Does this become a problem with this method?

Ravi - The nose and throat swab for genetic material of the virus, what we call PCR, has been shown to be very highly sensitive, with a very low false positive rate. You really don't get many false positives with that. But on the other hand, the antibody tests have a reputation for having a higher false positivity rate. So coming up with a positive, when the patient actually is negative. To address that, we looked at something like between 120, 150 patients with the antibody test. And we found only, I think, well, between zero and one false positive, so  this was actually better than we expected. So the tests actually performed very well. The finger prick antibody tests that people think are not doing so well, the selected ones performed very well in our hands. And that's the key thing. There are good tests and bad tests depending on the manufacturer. So if you choose the right test, you really can get high levels of accuracy.

Adam - And then how would you go about deploying this kind of system? Like, would it be test centres or hospitals, how would it work?

Ravi - In terms of direct application of our findings, I think we really should limit it to hospitals at the moment. And I think with the flu season coming in and lots of different viruses circulating, finger prick antibody test in 15 minutes upon admission would be very helpful because if it's negative and the patient has had symptoms for a week, let's say, you can confidently say they don't have coronavirus infection and probably have something else. So I think it could be very, very useful during periods of pressure on the NHS.

A bottle marked with a skull and crossbones, and the word poison, containing a dark purple liquid

16:24 - Novichok: What is it?

The poison has hit headlines lately, but what is it?

Novichok: What is it?
Phil Sansom

German doctors confirmed that the Russian opposition leader - and vocal Putin critic - Alexei Navalny, who fell ill on a flight to Moscow in late August, is the latest victim of poisoning with the nerve agent Novichock. This is the same stuff that was used in 2018 in Salisbury to attack the Russian defector Sergei Skripal and his daughter. Navalny has woken up from his medically induced coma, and doctors in Berlin are saying that while he's responding to verbal stimulii, they still have no idea just how serious the long term effects may be. So what is Novichock, how does it work, and where does it come from? Phil Sansom as the details…

Novichok is a Russian word that means ‘newcomer’ or ‘newbie’, and it refers to some of what might be the deadliest nerve agents ever made. In fact, Novichok is a family of 7 different agents, developed over the seventies and eighties in the Soviet Union and then Russia, carefully designed to circumvent chemical weapons bans and be undetectable by NATO.

They work by using two separate ingredients, or reagents, which when combined, react to produce a powerful poison that disrupts the human nervous system. It does that by messing with a chemical called acetylcholine that carries signals between nerves and muscles, or between nerves and glands, or even between nerves and other nerves.

More specifically, the poison blocks a second chemical that normally would break down the acetylcholine. You actually get too much acetylcholine building up at these junctions between cells. Your muscles get overstimulated and all lock up, effectively paralysing you, and potentially killing you from heart failure or suffocation. It’s a nasty death; and while drugs that block the acetylcholine receptors can sometimes help. that’s only if they come in time.

Novichok agents are extremely powerful - lethal at doses of milligrams - but part of what makes them so effective is that the two reagents are close to harmless on their own, and have shelf lives that are long enough to transport them across the world. The one that probably poisoned Sergey and Yulia Skripal in Salisbury in 2018 - called A234 - craftily developed using reagents and approaches that could be disguised as legitimate endeavours to produce pesticides.

If they’re so effective, though, why did the Skripals survive? And though Navalny is in a coma - how is it that his condition is supposedly improving? The answer is that people do survive, but the lasting injuries can be lifelong. One Russian scientist, accidentally exposed while he was developing the Novichok agents, never walked again, and his deteriorated over five years until he suffered a horrible, lingering death. 

Plus, if all this wasn’t bad enough, they seem to be incredibly stable molecules - one agent can stick around in the environment for half a century, making them a threat long after use.


Using bees to cure cancer
Ciara Duffy, University of Western Australia

Australian scientist Ciara Duffy from the University of Western Australia and the Harry Perkins Institute in Perth has discovered that the major component of honeybee venom - a molecule called “melittin” - can selectively kill cancer cells, and it looks particularly useful for targeting aggressive forms of breast cancer, including those referred to as “triple negative” tumours, that we currently struggle to treat. Chris Smith spoke to Ciara about this new work, published in npj Precision Oncology...

Ciara - For thousands of years, humans have looked at the products from bees for medicinal purposes: the honey, propolis, and the venom. And in recent years, there's been a lot of interest in terms of the venom's effects in cancer. So it's been shown to be able to kill cancer cells, but no one had actually tested that on all of the types of breast cancer and compared that to normal cells. So the way this project actually started was a veterinarian from Chile presented their research at a conference, and they'd taken these dogs, which had tumours on their sides, and they'd got these honeybees and stung into these tumours and they were shrinking and going away. And everybody in the audience went well, how does that work? Some researchers at the Perkins came together and I came in wanting to find a new treatment for breast cancer. And they said, well, we have a project looking at bees.

Chris - Where did you get the venom?

Ciara - I collected the venom from hives at the University of Western Australia, as well as at universities in London and Dublin in order to compare the venom from honey bees in different populations.

Chris - You better tell us how you actually get the venom out of a bee before you tell us what you did.

Ciara - Basically, I would take the bees by their wings or legs and put them in a box and then take them up to the lab and put them to sleep with carbon dioxide. And then very carefully under a microscope, dissect out the venom glands.

Chris - How much venom do you get per bee?

Ciara - Oh it's really tiny. It's like three microlitres. But what I do is actually dilute that because it's so potent.

Chris - What is actually in venom?

Ciara - Yeah. So it's a range of different chemicals and the main chemical is called melittin. And basically it is what has this main anticancer effect.

Chris - Right so you collect the venom, what do you then do with it?

Ciara - So I had grown up a range of cell lines in the lab representative of the different types of breast cancer, as well as normal cells. And basically diluted out the venom and tested on these cells to see if there was a difference in the effects.

Chris - And this is as simple as you just apply the venom in the liquid in which the cells are growing and see what it does to them?

Ciara - Yeah. So in terms of the cell survival, that's those experiments. And we also did microscopy to visualise actually what happened to the cells. And we can see that very quickly, the venom was able to burst open these cells and cause them to die. And remarkably the venom was more effective in these aggressive cell lines compared to the normal cells. So there was an interesting therapeutic window to play with there.

Chris - Do you know how the venom is selecting for the cancer cells, why they are particularly vulnerable, and not the healthy tissue?

Ciara - Well, there's some theories about this chemical melittin in the venom and it being more able to affect the surfaces of cancer cells because they're more vulnerable to such a chemical integrating into them. But in our research, we found that these molecules that are overexpressed or kind of more abundant in cancer cells are being shut down, and they're fundamental for the growth and replication and survival of cancer cells. So by melittin interfering with these, we think this drives some of the selectivity for damaging these cancer cells more than the normal ones.

Chris - And when melittin binds to a cancer cell, if you watch it down the microscope, what does it actually do to the cell?

Ciara - So what it does is actually 6-8 melittin molecules will come into the surface of the cell and dive in and basically form these pores or holes that cross the membrane of the cell and make the cells burst and die.

Chris - So if you've got something that makes holes in the membranes of cells, specifically cancer cells, does this mean then that even if it didn't kill the cell, you could use this almost as an adjunct therapy? You could mix it up with other drugs that sometimes struggle to get into cancer cells that are good at killing them. And then you can have a perfect cocktail of something that makes holes in cells and something that wants to get in and kill the cell?

Ciara - Yes, absolutely. And that's what we did. So we combined the compound melittin with a chemotherapy that's used for breast cancer treatment called docetaxel. And we found that the combination both in cells, but also in tumors that we had grown in mice, was significantly more potent than either melittin or docetaxel alone in reducing tumour growth and the proliferation of these tumours.

Chris - Taking this a step further then, because obviously this is early stage experiments, a lot of this work's just done looking at cells in the dish, so is the next stage then to consider how you might use this clinically?

Ciara - Yeah. So of course there's lots more experiments to do, but in terms of these aggressive and hard to treat cancers, one of the worst prognoses is for patients with triple negative breast cancer. And this one basically doesn't have any clinically effective targeted therapy. So what we hope is that we could start to develop a targeted treatment with melittin for these difficult to treat cells.


Old style telescope

A history of telescopes
Richard Dunn, Science Museum London

Adam Murphy’s been taking a look at how telescopes first came into being, by speaking to the Keeper of Technologies and Engineering and the Science Museum in London, Richard Dunn...

Adam - People, including me, have been fascinated by space since time immemorial. But looking up with our puny human eyes only gets you so far. To really see out, you need something more. You need a telescope. In some ways, the telescope seems like a simple idea. It's a few bits of glass, maybe a mirror, all put in a tube, but to find out how they came about, and what their legacy is, I spoke to Richard Dunn, Keeper of Technologies and Engineering at the Science Museum in London.

Richard - People were, certainly by the 16th century, thinking about how you might use lenses to see much further away. And there are lots of texts speculating, sometimes in the kind of magical way, about wondrous devices for doing this. The crucial development seems to be at the beginning of the 17th century, where someone works out that if you use diaphragms to cut out the outer parts of lenses, you'll manage to produce an image with much better resolution. At the end of September, 1608, we have a letter saying that there's a chap with a new device for seeing things far off. And this is in the Dutch Republic. Initially announced as a device for seeing your enemies from far away. So very much about use on land and at sea, not as something for looking out into the universe. And really from there, the telescope spreads incredibly quickly. Within six months, you've got cheap telescopes on sale in Paris, places like that. And these new low powered two lens telescopes are spreading throughout Europe.

Adam - So they were popular and a huge crowd of people could have them. But of that crowd, there is one name in particular that comes into focus.

Richard - Galileo Galilei is the person very much associated with the telescope, and its first uses in astronomy, even though he's not the first person to do recorded astronomical observations. He comes on the scene in the middle of 1609, hears about the telescope and begins making his own. And it's in the autumn, kind of October, November, that we know he's using an instrument that can magnify 20 times to begin doing astronomical observations, particularly observations of the Moon, but also other parts of the night sky. And this leads to his revolutionary work, the Sidereus Nuncius, the starry messenger, that's published March the following year.

And the reason he's so associated with the telescope and its use in astronomy, is because he gets this amazing book out. And he's the first person to print a report of telescopic observations, and makes a set of extraordinary claims. And he says that the Moon is not a smooth sphere, but it has mountains and valleys. He says that the Milky Way is not this kind of, solid band, but it's made of individual stars. It says that there are stars in the heavens that the eye alone can't see, you can only see them with a telescope. And finally he says that Jupiter has four of its own moons circling around it. And some of these are claims that really undermine the current view of how the universe was constituted at that time.

Adam - Those discoveries put a stamp on history. The four moons he saw around Jupiter are still known as the Galilean moons, but how did it revolutionise our understanding of our place in things?

Richard - The observations that Galileo announces, they don't prove that the Earth moves around the Sun, but they do undermine the traditional view of an Earth centered system with concentric spheres, perfect concentric spheres, moving around the Earth. The idea that the Moon is not a perfect sphere, undermines that. The idea that Jupiter has its own moons moving around it as the centre undermines the idea that all motion is around the Earth as the centre. But that didn't necessarily show that the Earth was moving around the Sun. And even when, later than the publication of the Sidereus Nuncius, Galileo announces that he's observed phases of Venus, even that doesn't absolutely prove that the Sun-centered system is correct.

So it's not actually until the 18th century that we get the first observational proof that the Earth is in motion around the Sun. And this is from the work of James Bradley, who after a long series of observations in East London in the 1720s, actually discovers what we now call the aberration of starlight. And this is an apparent change in the position of observed stars caused by the Earth's motion. And so it's only in 1729 when he announces it, that we actually have any direct observational proof. So it's quite interesting that people by that time, had long accepted that we live in a heliocentric system, but there was not actually absolutely conclusive proof that that was the case.

Stylised depiction of the fabric of spacetime.

32:28 - Looking into space with gravity

Some telescopes don't use light, they use gravity...

Looking into space with gravity
Ed Daw, University of Sheffield

The telescopes that the early pioneers of astronomy were using all relied on visible light reaching the Earth from far away in space. But telescopes can see in other ways too. In the last few years, an even bigger step forward has ushered in a new era in astronomy with the use of gravitational waves to see deep into space. LIGO, the Laser Interferometric Gravitational-Wave Observatory picks up ripples in the fabric of space made by massive objects like black holes, enabling us to study things in a whole new way. Ed Daw, from the University of Sheffield, is a professor of gravitational waves and dark matter, and spoke to Chris Smith about this heavy subject...

Ed - It's a pretty hard thing to explain, so I'm going to use an analogy; and because I'm from Sheffield, the analogy is going to involve snooker. Because as you know, we have these big snooker competitions at the Crucible every year. When you watch a game of snooker, what you're watching is balls roll around on a green-based flat table with slate under it, right? And so there's an idea from a snooker game that the motion of the balls doesn't really disturb the table. In fact the table's designed to be a very passive object. Now it turns out that that's kind of like classically, traditionally, people thought about space and time. People thought that space and time was a theatre in which objects did their things.

However Einstein showed that, in fact, the real world behaves a little bit more as if the snooker table, instead of being made of slate with felt on top of it, was actually made of stretch rubber. Now when you think about it, if you had a snooker game on a stretch rubber sheet things would be very different; so for example, if I put a ball down on the table, on my stretch rubber table, it would cause the sheet to become distorted. And so the background space-time in the same way is perturbed by the presence of matter, in the form of things like stars and even more exotic objects like black holes that you've mentioned. Now gravitational waves are a consequence of more complicated motion of objects. So back to the snooker table, imagine you have two snooker balls orbiting around each other. Now I know that doesn't happen with real snooker balls, but we don't have gravity in snooker...

Chris - Depends who's playing!

Ed - let's just extend it a little bit, right? So as the snooker balls rotate around each other, what are they going to do to the rubber table? They're going to make waves on it. And those waves are the analogy, direct analogy, of gravitational waves, and those are the things we've learned to detect with LIGO.

Chris - So Ed, if I may ask then: I detect a game of snooker by watching where the balls go. How do you detect your gravitational game of snooker? How do you pick up where a black hole is going?

Ed - The first thing is to detect the waves at all. Now because they're very, very tiny... I've said it's a rubber sheet, but actually spacetime is much stiffer than rubber, so the motions you're looking for are very tiny and subtle. So the detector in a nutshell consists of two ordinary pendulums - actually more than two, let's just pretend it's two - with masses on the end, separated by some distance. And when a gravitational wave comes through, both of the pendulums starts swinging; but it turns out they swing in such a way that the distance between them oscillates. And by using a laser detector you can detect the change in the distance between your two suspended bodies.

Chris - How big a difference are we trying to detect here?

Ed - If you have two of these pendulums separated by kilometre, the change in their separation moves by less than a thousandth of the diameter of a proton.

Chris - How on earth can you detect that?

Ed - By using very, very sophisticated, highly controlled laser metrology methods. You basically set up resonant cavities. The actual masses aren't actually ordinary pendulums, they're made out of mirrors that reflect infrared light, and then you make a resonator out of the two mirrors and you build up laser intensity between the mirrors; and when they start to oscillate, that causes the properties of the built up light between the mirrors to start oscillating as well, and you can amplify the effect of the tiny motion using the properties of the resonator.

Chris - What can this tell us, Ed, that we can't learn by using, say, the Hubble Space Telescope?

Ed - Well it turns out that much like many objects on earth don't actually admit very much light, there are plenty of objects probably in the universe that don't emit very much light either, or for that matter any other kind of electromagnetic wave. And those objects are therefore - with ordinary telescopes or other electromagnetic wave sensors - those objects are actually invisible. So we might have thought that there might be a lot of black holes in the universe before we had our gravitational wave detectors, but there are whole classes of objects, black holes for example, that it turns out were utterly invisible to all of our electromagnetic detectors, which have now been revealed by what happens when black holes collide, which is they emit some gravitational waves for a short time which are picked up by the gravitational wave interferometers in LIGO and Virgo.

Chris - How far across the universe will these gravitational waves propagate so we can detect them?

Ed - The one we detected very recently, the latest detection, which was from an object that happened last May, in May 2019, was 17 billion light years away. The source was that far away. So it's quite awesome how far away these objects are.

The Milky Way galaxy

38:36 - A successor to Hubble

We look at the telescope that's hoping to fill Hubble's sizable boots.

A successor to Hubble
Dominic Benford, NASA

Adam Murphy’s been looking at the Nancy Grace Roman telescope, a project that’s set to be a successor to the Hubble space telescope, one of the most famous telescopes of all time, with project scientist at NASA, Dominic Benford…

Adam - The Hubble space telescope is iconic. Sent into space in 1990, the images Hubble sent back are amazing and captured the imagination of millions, but it is 30 years old. It's getting on a bit. So a new generation of telescopes are being planned to attempt to fill Hubble's sizable boots. One of them is the Nancy Grace Roman telescope named for the first female executive of NASA, this telescope will seek to continue Hubble's legacy. I spoke to Dominic Benford, programme scientist for the telescope.

Dominic - We have designed the Roman space telescope to be able to conduct the kind of survey that astronomers haven't been able to do with any of the sets of tools they have had during the past generations. And that is to focus on being able to take very sharp images of wide areas of the sky with tremendous sensitivity, being able to see very, very distant objects and also to be optimised in the near infrared, which is wavelengths just slightly longer than what our eyes are sensitive to, because the near infrared wavelengths penetrate dust better, so it will allow us to see further into our own galaxy. And also, we'll be able to see the red shifted light from very, very distant galaxies. So it enables us to see farther. And so this combination of being able to see far into our own galaxy and far out into other galaxies, and to be able to do this very quickly, very efficiently, means that we can start conducting surveys where instead of looking at a few objects, a few galaxies or a few stars, we can start studying, monitoring and understanding millions or even hundreds of millions of galaxies, millions of stars, all the same time, to be able to conduct surveys that are more demographic where we really understand the whole, the entirety of these aspects of the universe all at once.

Adam - That means the Nancy Grace Roman telescope is designed to be more like a wide angle lens for space instead of a zoom lens. But how is it going to carry out its mission?

Dominic - The Roman space telescope surveys are designed to be able to answer pressing questions, both in cosmology and in exoplanet science. For cosmology, we will take a number of surveys of the distant universe so that we can understand the distribution of galaxies and how the universe has expanded over cosmic time. From a time when the universe was only a few billion years old to the present, when the universe is now 13.7 billion years old. And through watching the way the galaxies evolve, how they form, how they move towards and away from each other, we can infer the effects of dark matter, which is a large unknown component of the mass of the universe and dark energy, which is a recently discovered mysterious force that appears to be pushing the universe apart and therefore pushing all the matter in the universe away from all the other matter. And that we'll be able to take definitive measurements of this kind to understand the effects of these so that we might understand better the fundamental physics that drives the universe in its evolution.

Adam - And what about our own galaxy? What can be achieved when the telescope is pointed to the centre of the Milky Way?

Dominic - We plan on conducting a survey where we will look at the galactic bulge of our own Milky Way, which is where most of the stars in the galaxy can be found. So we'll stare at a wide patch of our Milky Way galaxy, tracking the brightnesses of millions and millions of stars, taking images every roughly 15 minutes over the course of many, many months. And we will look for the chance encounter when a star happens to pass in front of some other background star. And when it does this, because of general relativity, the light from the background star will be focused much like a lens by the foreground star and focused on us, as the stars move slowly through the galaxy. And that brightening is something that we can measure.

And by measuring the brightening with time, we'll be able to infer what the foreground star was like. And if the foreground star has planets, we'll see brightening from those as well. And in fact, even if these planets have large moons, we'll be able to see the brightening from the moons of the planets around those stars. And by doing this with millions of stars, we'll be able to track enough planets, thousands we think, of planets around other stars that we'll be able to make a complete demographic census of what planetary systems are like. In our own solar system we have the eight planets and that we can see essentially all the planets like that around another star, maybe not mercury because it's very small and close in, but certainly every other planet, even planets like Mars, we will be able to detect around such stars and be able to answer the question definitively, "is our solar system common in the galaxy? Is it rare in the galaxy? Or it may even be unique". And so doing this, we will understand our own place in the universe and how our source system got to be the way it is.

An image of a spiral galaxy

44:10 - The biggest ever telescope

The square kilometre array is set to be the biggest telescope, but how does it work?

The biggest ever telescope
Phillip Diamond, Square Kilometre Array Organisation

Work is underway on an equivalently impressive project, which will be the most powerful telescope we’ve ever built. It’ll enable us to see at least 10 times further than we can already. It’s the Square Kilometre Array or SKA, which is a radio telescope, and it’s unusual because it’s going to span continents: part of it is in Australia, and the rest is in southern Africa. The HQ though is in the UK at Jodrell Bank Observatory, and the Director General is Phillip Diamond, who spoke to Chris Smith about the project...

Phillip - Well, there are different types of light. So, yes, Galileo observed visible light that we see with our eyes, but other types of lights across the, what we call the electromagnetic spectrum are x-ray, ultraviolet light, the visible is sort of in the middle of the electromagnetic spectrum. So radio waves are what we call long wavelength - part of the electromagnetic spectrum. And in order to observe the universe in radio waves, we need to build large dishes to pick up this long wavelength radiation, and so using big dishes like that at Jodrell bank, which is 76 metres across.

Chris - What can radio waves, and those other sorts of radiation cause they're effectively forms of light that we can't see aren't they, what can they tell you about a distant object that I couldn't learn from say looking at it with the Hubble space telescope?

Phillip - Well, if you could see the universe with radio light as we do, it looks remarkably different actually from observing with visible light. So with visible light, you pick out the stars, the very bright objects like stars and galaxies etc. With radio waves, we pick up a lot of gas, very energetic phenomena, the jets exploding from black holes. But one of the main things that we can do is observe hydrogen - the most common element in the universe. And that is only visible in the radio part of the electromagnetic spectrum.

Chris - Why does it matter that you're seeing hydrogen? Why is that important?

Phillip - It is the most common element in the universe and therefore it's the constituent of much of what is out there, it forms the majority of the material in stars, the majority within galaxies, it traces the dynamics of galaxies. And as we look further and further into the universe, closer to the big bang, we can actually use observations of hydrogen to watch the universe evolve in time to what we see when we look out into space now.

Chris - The thing about the universe is that we believe that it began with a big bang that was about 13.8 billion years ago or so, but initially it was far too hot for anything to exist. Hydrogen didn't exist. So does that mean there's a limit to how far back in time you could look? If you can see hydrogen?

Phillip - There is - it's about 400 million years after the start of the big bang, where we start to see the hydrogen in the universe beginning to form the first stars and the first galaxies, at least we presume that to be the case. It's with the SKA that we actually hope to see this for the first time to understand the details of how those first stars and first galaxies were formed. And then what we want to do is essentially make a movie of how the universe evolves in time from that point to about 400 million years after the big bang.

Chris - One of the striking things about it is that you've got multiple countries involved and it's spread over a huge distance. Now, why is that? Why not just have one big dish in one place.

Phillip - A big dish, like the Lovell telescope is 76 metres in diameter. The largest big dish in the world which could move is a Green Bank West Virginia, which is just over a hundred metres. We'd like to build bigger dishes, but that's just not practical. In the fifties and sixties, what was realised was if we had smaller dishes that we connected back then with copper cables, but now with fibre optics, and spread them apart, we could essentially synthesise a much larger dish, especially if we had many of these smaller dishes. But if you think of the big dishes as like a wide angle lens, then with what we call interferometers moving the smaller dishes apart, it's like a zoom lens.

Chris - And just out of interest, how much data will be flowing down these fibre-optics to collect all this information from this enormous array of dishes?

Phillip - Well, the volumes are truly huge. So the raw data we will generate from the dishes is essentially the same scale as the entire internet of the planet, but it's on our own dedicated network. And it's just not as chaotic as the data that flows over the internet. We have fixed formats that we control through this dedicated network. We quickly reduce the volumes of data, they're still enormous, we'll be generating on the order of 700 petabytes a year into the archive for the astronomers to use. And that dwarf's the total generated by Facebook and Google, for example. So it really is a big data problem that we're tackling to deliver this new science to users.

Chris - And you've mentioned obviously giving us an insight, hopefully, into the earliest times of the universe's existence, what other projects have you got earmarked for this once it goes live?

Phillip - Well, our global science community has actually generated the science case, which is about 2000 pages long. It's a huge, huge range of science, but a couple of examples - one is that we'll be looking for the origins of life itself. We'll be trying to detect the molecular signatures of prebiotic molecules and potentially even amino acids. If we discover that is widespread out there in the universe, that will have very interesting implications for the origins of life. And another, to connect back to LIGO, for example, we will also be looking for gravitational waves. We'll be doing this by looking at the signals from pulsars, which are the rotating remnants of large stars, which have exploded. We'll be looking at these networks of pulsars across the universe and seeing the ripples of gravitational waves as they pass through.


QotW: Why do I need to pee more as I near the toilet?

To relieve Charlie of his question, Katie Haylor asked physiologist Bill Colledge from Cambridge University to expel the answer...

Katie - On the forum, user syphrum said that “As you get older you will find there are no rules about holding on to a pee you will find it has a mind of its own”. So to relieve Charlie of his question, I asked physiologist Bill Colledge from Cambridge University to expel the answer.

Bill - I believe that this is sometimes referred to as “latchkey incontinence” - the urge to pee becomes greater the closer you get to home and the toilet. It can also apply to any toilet that you know you can access. The urge is caused by neural circuits in the brain that become activated in anticipation of being able to use the loo.

Katie - Bill says it’s all about what’s called a conditioned response stimulus.

Bill - A conditioned response is one where a neutral stimulus is paired with a neuronally encoded physiological response over time. The most well known example of this is Pavlov’s dogs who were conditioned to the sound of a bell as a signal for food. After the conditioning, they would start salivating when they heard the bell even though no food was provided. Humans have quite a few conditioned responses – for example, you will often start to salivate simply at the thought of a meal. 

For the peeing conditioned response – from an early age we are taught to associate the bathroom with peeing so the closer we get to one, this subconscious conditioning kicks in and causes physiological responses to increase the urge to pee.

Not everyone will have the same response however – it will depend on how much they have been conditioned and whether they can break this conditioning by delaying going to the toilet as long as possible after the urge to go.

Katie - Bill Colledge, thanks very much. This isn’t the only type of incontinence issue people can experience, and overall urinary incontinence is quite a common problem. So if the urgency that Bill described, or any other type of urinary issue, is getting in the way of your day-to-day life, it might be worth seeking out help from your doctor.

Next time, we’ve got our eyes to the skies to answer this question from listener David.

David - What method of time would you use in travelling through space, as a day, month, year, would become meaningless?  And how would this affect the body clock?


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