Wielding (quantum) fields!

Quantum field theory takes an infinite number of field configurations and add them up with the proper weighting to come to a single conclusion. The Standard Model is one well-known example, but this could be much, much more useful. For example, we could predict readings on compasses – something we can’t do right now – at different altitudes as climbers go up mountains. It might sound simple, but gravity, and all the infinite number of fields generated by planet earth, are actually incredibly complicated.

 

Gaussian free field model by Samuelswatson via Wikipedia.

What has Juno found on Jupiter? Part II – It’s magnetic

Built with a 20 radius and designed to spin, Juno is made to measure the magnetic field of Jupiter. Thanks to Juno, we now know that the planet’s dipole is the opposite way round (North and South) to Earth, and tilted ~10^o from its rotational axis. The strength of the magnetic field (20 x that of Earth’s!) allows us to calculate how long a day is on Jupiter – because we can’t tell just by looking at the bands: they seem to move in opposite directions to each other and at different speeds! It also allows Jupiter to deflect solar winds as far out as 6 million km from the planet and hold onto its atmosphere. At this point, we also see weird effects that Juno is attempting to explain, such as ring-like features, known as Kelvin-Helmholtz instabilities, which scientists think may travel along the planet’s magnetic field lines. As well as the dipole, these include weaker quadrupoles and octupoles.

 

Jupiter's magnetosphere showing the Io Plasma Torus (in red). Yned via Wikipedia Commons.

What has Juno found on Jupiter? Part I – Water and weather

One of Juno’s findings has been some measurements of the Great Red Spot – a giant Jovian storm that could fit three Earth-sized planets inside it. Although Juno has the power to image up to 350 km deep into the Jovian atmosphere, it turns out that the Great Red Spot is deeper than this. Measurements of its temperature show that, for the first 80 km, it is cooler than the surrounding atmosphere, and below that, it’s warmer. We don’t know why, but it could be linked to how the storm started, and whether it's permanent or will disappear with time.

 

The Great Red Spot has been observed for over 300 years now. It's so large it could accommodate three Earth-sized planets! Wikimedia Commons

The smallest astronauts ever

The extremes of space are sufficient to rip the atmosphere off Mars (our is protected by our magnetic field!) – so what hope does a little bacterium have? Actually, it turns out, rather a lot.

Despite very low pressures and temperatures and direct exposure to ionising radiation, Deinococcus bacteria dumped on the outside of the International Space Station managed to survive there for three whole years^[1]! They’ve also been found to survive on and inside meteorites, and scientists are excited to find that they could be little interplanetary travellers – perhaps even explaining where life came from on Earth (yes! We might all be aliens!). This theory is known as panspermia.

 

Public Domain via Nadya_il (Pixabay)

Categorising Things is “Evil”

We label things every day: that man is tall, this book a thriller, leaves are green. How tall? How thrilling? What shade of green? We take the relative and make it absolute, categorising the life out of it to streamline communication. Labels are the oil on a squeaky gate, and most people never question them.

When I was a child, I hated labels: they didn't make sense to me. Was a tall child tall, or short because they were a child? What if my eye colour wasn't an option on the list? Why did we need to classify books anyway, and where did one genre end and another begin? Wasn't it easier to just describe them? ...Surely that's what blurbs were for.

Categories lead to bad writing. If you learn that everybody can be described as a tall, frizzy-haired bossy woman, you always tell – and never show. Telling is boring. It loses the magic and the mystery of the woman who peers down between dark, raggedy fronds with a floating look and says tartly, "I told you to put the other end on first!"

I resisted for a long time. Declined to answer; drew an extra box on the multiple choice question. But eventually I was indoctrinated. How? Why?

...If you get told something often enough, again and again and again, it starts to sink in. Perhaps you don't understand the categories, but you can pick from them (even if you pick wrong). My teachers needed me to say that my character was bossy so they could prove I understood what adjectives were. Friends had to like the same genre of music. The NHS wanted to classify my growth rate. So I shut up and categorised for an easy life.

Science uses categories all the time. Species separate from species (did you know the only taxonomic difference between moths and butterflies is that butterflies are prettier?). This is incredibly useful for explaining the patterns and rules in science, but it's also limiting. As we discover more science, we have to revise our categories as they no longer make sense: such as the advent of DNA, which gives us new insights into how animals are related, or the discovery that electricity was the flow of negatively charged electrons, which revealed that our "conventional current" arrow went in the wrong direction!

In learning institutions, even the science subjects are carved up and divided: physics, chemistry, biology, maths… Perhaps, then, it should come as little surprise that so many of the unanswered questions in science take place at the intersection of these fields. To answer them, we need people who are experts in different fields talking and working together, but we actually need more than that: we need polymaths, people who are computational biologists, physical chemists, scientific philosophers, and so on…

I had a quick look at the Things We Don’t Know database, and picked out just a few very fascinating things that cross over scientific fields, from biology to physics to chemistry to computer science to geology to engineering to psychology… and so on ad infinitum. These are they:

Could robots soon have 'human-like' vision? 
Research has been carried out into replicating the muscle motion of the human eye using soft materials and pressure-sensitive piezoelectrics. This could allow robots to "perceive" the world in a way we find more intuitive, and may even help us learn about human visual processing.

Could we capture and store our waste carbon dioxide? 
Scientists think that up to 90% of carbon dioxide emissions could, instead of being released, be captured and stored underground or underwater, where, at great depths, high pressure cause it to liquefy. In the ocean, it shows “negative buoyancy”, sinking to the sea floor, whilst in rocks it can be drained into tiny natural pores in rocks: this is called geological sequestration. Scientists are still exploring where this could take place and how long the carbon dioxide could be stored.

Could we treat mental health problems with birdsong? 
Humans may get psychological benefits from listening to bird calls, including boosts to mood, attention and creativity. This “biophilia” – the idea that being amongst nature makes you happier and healthier – is sufficiently established that Alder Hey Children’s Hospital in Liverpool play birdsong in their corridors, as does an airport lounge in Amsterdam! It’s even been applied as a form of dementia treatment. New work led by the National Trust aims to explore how human brains are affected by birdsong.

How can we measure uncertainty? 
Entropy is a measure commonly used thermodynamics to assess the disorder of a system. However, computer scientists and cryptographers now talk about information entropy. The greater the uncertainty about something, the more information is needed to describe it – so the more entropy or disorder. How did photochirogenesis evolve? Photochirogenesis – the development of handedness in biological molecules (where all natural molecules are either left or right hand mirror images of asymmetric molecules), may have developed because of polarised light in meteorites. If this is true, the origin of life could be in stars.

Is time in our minds? 
Is time an illusion? How can we tell? And, if it’s just in our minds, why is it used in classical mechanics equations? Does time really only go in one direction, or is this an illusion of human perspective? Our current direction through time is always forwards by definition, but on what grounds do we define it like this? Underpinning this could help us understand the concept of time travel and the science behind what we really mean by it.

And on that philosophical note… If you or someone you know is working on one of these topics, we’d love to hear from you. Perhaps you can tell us more about how your research is going, or some of the challenges in the field!

I was inspired to write this post after hearing a talk by Dr Julia Shaw on the label “evil”. 'Evil' throws up all kinds of problems not only because it's a highly subjective category (like most), but also because it sticks. Once labelled evil, you are evil forever. You can live a good life, behave well, be compassionate, but screw up once and you are evil. Your misdeed will be carried with you forever and you can never shake off its label. Evil is immortal.

Magnetic Monopoles and Geometry

Take a balloon, rub it against your jumper, then stick it to a wall. Why does this work?

By rubbing it on your jumper, you’ve given it extra electrons and, since the electrons have a negative charge, the balloon now has a negative charge too. So, why does this make it stick to the uncharged wall? Because, by comparison, the wall is more positively charged – and positive and negative electric charges attract. In some materials, charged particles even can shift about a bit to give a more positive side near to the balloon, creating stronger sticking.

Charged balloon attracted to the hair of a cat. Public domain.

Mysterious Mo

Why is stainless steel stainless?

Iron vs Steel

Steel is made from iron, but it’s not the same thing: steel is an alloy - iron doped with other elements to engineer new, useful properties. Some of these elements have been especially selected to provide certain properties, but not all metallurgy is that well understood: some elements have simply been stuck in and performed well - and we don’t know why.

Is there a ninth planet in our Solar System?

By now, you’ve probably heard the hubbub in the news about the hypothetical “Ninth Planet” in our Solar System, and, unfortunately for those of us who studied astronomy before 2006, no, it’s not Pluto. There’s a new Planet Nine on the block, although no-one has ever seen it and we don’t actually know if it exists.

Yes, some scientists think there may be another, unseen planet in our Solar System. How can they think that?

Why haven’t scientists seen Planet Nine yet?

In our solar system, planets are generally considered to be visible things - get yourself a 12-inch telescope and you can see Pluto, and that’s not even a planet any more! So yes, it sounds daft to say that there’s a whole other planet in our Solar System that we haven’t seen yet, but, in our defence, it’s very far away.

Planet Nine is thought to be a trans-Neptunian object - a minor planet that orbits the Sun at a distance further out than Neptune. Both the Kuiper belt and the Oort cloud are included in this region, and Planet Nine is thought to orbit somewhere between the two.

The Oort cloud is a spherical region of icy debris thought to surround the Solar System. Although it was thought to extend from 5,000 to 100,000 Earth-Sun distances, it may start much closer to the Sun. Image credit: NASA and A. Feild (Space Telescope Science Institute)

Why do scientists think Planet Nine exists?

The Search for the Graviton

What holds the world together? It sounds like a simple question - but it isn’t.We know of four fundamental forces of nature that seem to be doing the job, but have only found three exchange carrier particles (particles which give rise to the forces between other particles). Physicists like symmetry, and we like to think that the universe does too. Faced with the scenario of more forces than carriers, it is natural for a physicist to assume we’re missing one.

So far, we have found photons, which carry the electromagnetic force (which describes the interactions between charged particles); W and Z bosons, which carry the weak nuclear force (responsible for radioactive decay); and gluons, which carry the strong nuclear force (which holds the nuclei of atoms together). But what about gravity?

Not all types of elementary particles interact with all other types, and only some fundamental particles interact with particles of the same type. For example, photons do not (directly) interact with other photons, or with gluons. Image credit: Public domain

This idea is summarised nicely in an article by science writer Brian Koberlein: in quantum field theory … [you] start with a wave form and then ‘quantize’ it, you break the wave down into the smallest amounts of it that can exist (for example, photons are quanta of light). This has been used with photons, and doing so with gravitational waves leads to the idea of gravitons.

However, this approach encounters some problems when tackling gravity. General relativity tells us that that gravity and the curvature of spacetime are intricately linked. As matter travels through spacetime it causes spacetime to curve around it, and as spacetime curves, this tells matter where to move. It is this motion, caused by the curvature of spacetime, that can be considered ‘gravitation’ ^[8].

The Case of the Jumping Carbons

Imagine you are inside a nuclear reactor, a UK design. Not only are you inside it, but you are part of it; a carbon atom inside the graphite core which houses the control rods and fuel rods (the ‘moderator’). Around you the environment is glowing with heat and radiation, all given off in the splitting (fission) of uranium-235 nuclei. The temperature of 450°C is no problem, and you remain tightly bound in a lattice arrangement with your fellow carbons.

However, when the uranium nuclei split, they spit out more neutrons which pelt towards you at high speeds. One slams into you, and you slow it down, as is your job, so it travels at a suitable speed to cause more fission events. In this process you absorb the neutron’s energy, and get knocked out of your slot in the lattice. You whiz towards your fellow carbon atoms, knocking more out of their spaces like a billiard ball, wreaking havoc in the strict order of the graphite crystal. Eventually you transfer all of your extra energy to your neighbours and come to rest, filling a vacancy left by another displaced carbon or squeezing in between the orderly lattice layers (as an ‘interstitial’). Here you wait, ready to absorb the excess energy of the next neutron. The upheaval is routine to you, as during your life in the reactor you may switch places up to 30 times.

A finite element model of a graphite sample and how the model behaves when irradiated or heated. Image credit: Dr Graham Hall. Manchester University

This is just one atom, but what are the consequences of millions jumping around like this?

Well, the effects are unpredictable. The radiation barrage that the graphite endures can cause it to change its material properties; its thermal expansion, strength and even its dimensions, in strange ways. Even to the human eye, these changes would be noticeable. The moderator can change shape by up to 2%, depending on the grade of graphite; a surface that started smooth may finish rough. The dimensions may warp so that the control rods used to restrain the nuclear reaction may no longer fit into their channels. It is clearly important to completely understand how the graphite will change when designing new reactors or maintaining the existing ones. The problem is that we don’t.

100,000 Years Later

The problem of making future predictions about the destiny of long-lived nuclear waste.

What is nuclear waste?

Depending upon what you put into a nuclear power station and how you operate it, you get different products out. Most reactors use uranium dioxide fuel, UO₂, and over 90% of the “spent fuel” is still uranium compounds, with a little plutonium. Although it is called spent fuel, so much uranium still exists that it may be recycled to generate more electricity and remains hot for years. However, “ash” products that absorb neutrons and slow the reactions build up as the fuel operates, the rate that energy is produced drops and stops being efficient. Then the fuel will be replaced, useful uranium extracted and recycled and the rest disposed of.

Some kinds of reactors extract more energy and are more efficient, such as fast breeder reactors. These make products like plutonium-239 (Pu-239) that sustain the chain reaction - nuclei falling apart and giving off energy. When the rate plutonium-239 is produced is faster than it is used up, the reactor can get 60 times as much energy from the original uranium and more plutonium products result. However, there are no fast breeder reactors in the UK because plutonium-239 is one component used to make nuclear weapons - not something you want to be storing in large quantities. Plutonium-239 and other minor actinide products of nuclear power generation remain dangerous for over hundreds of thousands of years. Although the longer a radioactive material remains dangerous, the lower the danger (because they produce radioactivity more slowly), fresh spent fuel is so concentrated that standing unprotected before it would get you a lethal dose in seconds, and you would die of radiation sickness in days.

How can we store nuclear waste?

The Inspirational Butterfly

An Insight into Developments in Solar Power

The UN is calling for drastic action to be taken to stop climate change in its tracks. With any luck an agreement will be reached this year on the actions that will need to be enforced by 2020 to tackle this worldwide issue^[1]. As a result, countries are desperately attempting to reduce their carbon emissions, and focus on renewable energy sources is increasing. If the right developments are made to improve efficiency and distribution of renewable sources, we could be one step closer to establishing a sustainable worldwide energy supply and battling the ongoing threat of climate change.

The prospect of being able to harness energy from the Sun is one that has captured our interest given its relative reliability, and solar power is already a widespread phenomenon. However it does not yet compare to the cost of generating power from fossil fuels, and a result is often considered to be less economically viable.

The UN conceded in the Kyoto Protocol that limiting global warming to just 2 degrees, relative to the pre-industrial temperature level, would be necessary to reduce harmful climate impacts. For this to be achievable a 75% decline in carbon emissions by 2050 would be necessary^[2]. If innovations in solar power continue to progress at the current rate, it could become the world's largest energy source by 2050. Today, solar photovoltaics and concentrated solar power contribute 16% and 11% to global overall consumption, respectively^[3]. Image credit: Northern Alberta Institute of Technology via Flickr (CC BY-ND 2.0)

Given the positive effect a switch to solar power could have on the climate, there is much ongoing research into whether the efficiency of solar power can be improved. Inspiration for this goal can sometimes be found in the most unlikely of places..

The Impossible Quasar at the Dawn of the Universe

The recent extraordinary discovery of the biggest and brightest quasar of the early universe has intrigued astronomers worldwide. The reason behind this? The quasar - SDSS J010013.02+280225.8 (affectionately nick-named J0100+2802), is far larger than current black hole theories predict it should be^[1].

Among the oldest and brightest entities in the universe, quasars eject jets of very bright light that can be seen from lightyears away. It was initially believed that different events were being seen when quasars were observed, but it was later established that our line of sight affected the appearance of the quasar, for example a blazar is a quasar with jets that are pointing towards Earth. Image credit: ESO/M. Kornmesser

Technicolor theory and the Higgs

Earlier this year, claims have been bouncing around the internet about the results of the biggest discovery in particle physics. That the Higgs boson, the boson meant to help us understand where the origin of mass in particles comes from, is not actually the Higgs boson and that Peter Higgs should have his Nobel Prize whisked away from him quicker than you can say ‘Large Hadron Collider’.

The Compact Muon Solenoid (CMS) is one of the detectors in the Large Hadron Collider where the Higgs boson has been detected (the other is ATLAS). Data from this is processed by supercomputers which produce the beautiful collision diagrams for scientists to pore over and deduce what particles have been detected. Image credit: CMS/CERN

But surely the Nobel committee can’t have given away such a prestigious award so carelessly, without having checked the integrity of the results particle physicists have spent years working on? I spoke with Dr Alexander Belyaev from the University of Southampton, who explained how these articles have somewhat missed the point, and how it relates to his research into Technicolor theory. So what is a Higgs boson anyway?

A Swift glance at red dwarfs

November 20, 2014 is a huge day for NASA’s Swift spacecraft, as it marks the tenth anniversary of its launch. Currently orbiting our planet, Swift is scanning the skies for potential sources of events known as Gamma-ray bursts (GRB’s). Each burst is a huge, but relatively brief, flash of very high energy radiation coming from interstellar space. Astronomers believe they happen fairly frequently (we detect around one per day according to NASA), and last from a few milliseconds up to a few minutes. Swift’s role is to detect these events using the Burst Alert Telescope (BAT), in order to find out what exactly is causing them. This telescope has a very wide angle lens, which can see about a sixth of the sky at any one time – about the same as one of our eyes can see - and scans around 88% of the entire sky each day^[1].

Gamma-ray bursts can happen at any moment, so Dr Kim Page and her team at the UK Swift Science data centre (UKSSDC) based in the University of Leicester take turns to be ‘on-call’ for when BAT is triggered. There are two ways BAT can be provoked into action; by a quick rapid spike in high-energy waves or by a cumulative increase in a particular part of the sky over a longer period of time. These two mechanisms are known as the “rate trigger” and “image trigger” respectively, named for the specific way in which they pick up radiation. If the telescope is triggered it sends a message to the various cameras onboard Swift to “switch on”, which then turn and face the area of sky from where the original signal was first detected. At the same time, it sends an automated SMS to the on-call team members at the UKSSDC, whilst also writing each team member an email containing the relevant data about the location, time and intensity of the trigger source. The X-ray, UV and optical cameras on Swift can then investigate the radiation burst further. The Swift team have found this to be extremely effective and usually the phenomenal increase in energy has a Gamma-ray burst at the centre. But, as we will see, this is not always the case.

The Swift spacecraft has been orbiting the Earth since 2004, collecting data about the locations of over 800 gamma-ray bursts; extremely high energy events which occur deep in space. From understanding more about the causes and nature of GRB’s, astronomers hope to understand the early universe better. Image credit: NASA E/PO, Sonoma State University/Aurore Simonnet

Occasionally, an event which isn’t a GRB will cause the detectors to swing round and peer into the depths of space. On April 23, 2014, BAT picked up a huge influx of energy coming from a small constellation known as Canes Venatici (part of the Ursa Major group). The image trigger alerted Dr Page with a text message at around 10pm, telling her and her team that there was a potential GRB in this constellation. Within two minutes the Swift cameras had collected as much data about the position of the source as they could. This data was then cross-referenced with catalogues of stars and galaxies, to see if this patch of sky had produced GRB candidates on previous occasions - making it more likely to be a “false positive”. As a matter of fact it had – and the team found that the patch of sky they were looking at contained a binary red dwarf system, about 60 light years away. So, by then we knew what was setting BAT off, says Dr Page, Red dwarf stars are well known for their highly energetic flares. But the fact that this system could be expected to produce powerful flares didn’t prepare Dr Page and her team for the sheer enormity of the flares they were seeing this time.

India's MOM seeks answers

In 2010 the Indian Space Research Organisation (ISRO) began a mission to send a spacecraft to orbit Mars – the Mars Orbiter Mission (MOM). Three years later they launched the craft and finally, on 24th September 2014 it reached its destination. The spacecraft’s primary objective is to test and develop the necessary technologies needed for interplanetary space travel - a technology which will allow India to plan future missions through the solar system and beyond. Its secondary objective, though, is scientific research. As the craft orbits the planet it will be collecting data about the planet’s atmosphere and surface.

The journey to Mars, though relatively short compared to a journey to other planets, is a complicated one; out of the 23 missions which have been launched to orbit Mars, only 10 have been fully successful. For India, this maiden voyage means the chance to explore the red planet whilst also developing their technological know-how. The whole mission has cost ISRO about $70 million - making it the cheapest vessel to enter Mars’ orbit since exploration of the planet began! For comparison, NASA had to pay a similar amount per seat to fly their own astronauts to the International Space Station in a Russian spacecraft. This is an incredible feat for technology and may lead to reduced costs for future missions to Mars.

An artist's impression of the Mars Orbiter Mission spacecraft orbiting Mars. The basic structure was based closely on ISRO’s first mission - Chandrayaan-1. Image credit: Nesnad, via Wikimedia Commons. (CC-BY-SA-3.0)

Mars is the outermost of the four rocky planets in our Solar System, and is also Earth’s neighbour. Despite having similar rocky compositions these two planets couldn’t be more different. The oceans, flora and fauna which are so prevalent on Earth are completely absent on Mars, and yet the two planets’ orbits are separated by a mere 54.6 million kilometres – a galactic stone’s throw away. Astronomers and planetary scientists have been studying the planet for a while now, and yet there is still so much we cannot decipher about the planet and its history.

Cosmic Inflation, BICEP2 and Planck

Cosmic inflation is the exponential expansion of space in the early universe. In other words, how did the universe go from being so small at the time of the big bang to the size it is today?

But why do we even think this occurred? In the 1920's, astronomer Edwin Hubble noticed when looking at galaxies through a telescope, that the galaxies were actually moving away from one another. The further apart they were, the faster they moved.

The only logical explanation for this was that the universe was in fact expanding. If everything seemed to be moving away from each other in all sorts of directions, then surely at some point in the past, it must have been very small, hot and dense. This led to what we now know as the Big Bang Theory, so called because of the implication that the universe began a single point and exploded outwards.

The Big Bang is believed to have occurred 13.7 billion years ago, after which the universe rapidly expanded in a period of time we call Inflation. Scientists are still searching for conclusive evidence of this, and seek to test the two fundamental assumptions upon which it is based; that the same physical laws apply everywhere in the universe, and that on large scales on large scales the universe is homogeneous and isotropic. Image credit: NASA (public domain)

Everywhere we look in the universe, we see billions of galaxies evenly spread. Up until 1979, nobody could explain why this was. That was until a young cosmologist by the name of Alan Guth put forward a possible solution to the problem; he called it inflation.

The Quest for Invisibility

Since long before Harry Potter, scientists have been searching for a way which can allow things to pass us by unnoticed. The invisibility cloak which features in J.K. Rowling’s books may seem magical and otherworldly, but in fact devices which have the effect of making objects completely disappear are much more tangible than you’d think. While they may not look like a silky blanket, cloaking devices are very effective at manipulating signals and jamming detectors so as to obscure the truth about their location.

So there it is, we’ve done it. We have successfully created magic and are able to hide enormous ships or helicopters from being spotted by the enemy – haven’t we?

Well, not exactly. The perfect cloaking device is still just a theoretical concept. Camouflage paint is often applied to try and confuse the eye, “stealth” coatings are used to hide from radar, while cooling techniques are employed to reduce the amount of infrared emission coming from the object trying to stay hidden. However, while these techniques are effective at helping to disguise ships and aeroplanes, we can hardly call them invisible. It is hoped the answer lies in the development of metamaterials – materials which possess properties not found in nature.

The electromagnetic spectrum covers all wavelengths of radiation, from radar to visible light to x-rays and gamma-rays. Until last year we could only hide things from very specific parts of the electromagnetic spectrum, in some cases by making the object more visible in other parts of the spectrum. Image credit: NASA (public domain)

The development of such materials has huge implications for lens and invisibility devices. The idea of cloaking devices is to create a material which can take an incoming signal, say visible light, and then send it on its way without any interruption from the cloaked object. If you could create a material which can do this effectively enough, it will trick any detectors into thinking there is no object to be seen, since there is no radiation signal to be detected. In theory it’s possible, but there are many obstacles blocking the way.

Mapping spacetime around supermassive black holes

Black holes come in many sizes ranging from tens to millions, or even billions, of solar masses. Their incredible size means they exert immense gravitational power over other objects, and can even warp space-time to such a degree that they behave like lenses and actually bend light around them – a process known as gravitational lensing. In many cases a large black hole will acquire another incredibly dense friend, for example a small black hole or a neutron star, which will orbit the central black hole whilst slowly spiraling into it. These physical systems are known as Extreme Mass Ratio Inspirals (EMRI's), called as such because of the vast mass difference between the two objects.

Physicists often consider space and time as a single continuum, called spacetime, which consists of the 'usual' three dimensions (up/down, left/right and forwards/backwards) plus time as a 'fourth' dimension. Spacetime is bent by anything with mass - an effect we see as gravity. Image credit: Wikimedia commons

Einstein’s famous theory of general relativity states that any mass will bend spacetime. Black holes, because they are so incredibly dense, will stretch and curve space-time to a much greater degree than our planet ever could. However something relatively tiny, like the Earth, still has an effect. For EMRI's, you can think of this as being like a bowling ball placed on to a taut sheet - the bowling ball will sink causing the sheet to stretch. If you place a marble onto the same sheet, it will also sink a little bit into the sheet because it has its own weight, but the bowling ball makes a much larger dip than the marble.

But getting out sheets, marbles and bowling balls isn’t a very accurate way of modelling these systems – so how is it done? I spoke to Dr Sarp Akcay, a postdoctoral fellow at the University of Southampton and an expert at creating models simulating the orbits of EMRI's.

Chariklo, the Celestial midget

In March, the European Southern Observatory in Chile made an astonishing discovery that has surprised astronomers. It’s no secret that the great gas giant, Saturn, has an impressive set of rings surrounding it - and while less widely known, in fact all Jovian planets (Neptune, Uranus, Jupiter and Saturn) have ring systems around them. These planets are the largest in our solar system, and have a tremendous gravitational pull on rocks, dust and gas due to their great size which keeps their ring structures in place. However, nestled between Saturn and Uranus, they’ve discovered a comparatively minuscule object with a fraction of the gravitational strength which has its very own rings - something many astronomers believed to be impossible.

Artist’s impression of the asteroid Chariklo, and its newly discovered rings.
Image credit: ESO/L. Calçada/M. Kornmesser/Nick Risinger (skysurvey.org)

Chariklo 10199 is what’s known as a Centaur, an object which originates at the very limits of our Solar System (a region called the Kuiper Belt) and carries characteristics of both asteroids and comets. This particular Centaur is merely 250km wide, that’s roughly the same width as Lake Victoria in Africa and barely 0.0004% of Saturn’s volume, making it a celestial midget. It’s this midget which has been discovered to carry its own ring system made up of space dust and particles – just like the Jovian planets.

Why is it that this space boulder has rings too? How did they get there? What can they tell us about our Solar System?