Universe Today: The Juno mission just launched to Jupiter and there are lots of other space missions going on. What are some your favorites and your hopes of what those kinds of missions will discover?
Brian Cox: The enormous question for space exploration is origin of life on other worlds. That is currently THE big question. We’ve seen discoveries recently about possible, plausible evidence of flowing water on Mars. There’s been evidence for awhile that there is perhaps subsurface water, but seeing what looks to be the signature of flowing, briny water — today — is very suggestive. On Earth, where we have water we have life, so this new finding makes Mars even more fascinating. The ExoMars project, the joint European-American mission to Mars to look for life is going to be one of most exciting missions yet, because there’s a good chance of finding it.
The ExoMars/Trace Gas Orbiter mission is a joint mission being developed by the European Space Agency (ESA) and NASA/JPL. This mission would be the first in a series of joint missions to Mars for ESA and NASA. Credit: NASA
Now we’re heading off to Jupiter, and Europa is actually a fascinating place for the same reason. There is a huge amount subsurface water on Europa, and there has been speculation that colored markings on the surface of Europa could be life. It looks as though there may be seasonal shifts, and that could be possible cyanobacteria in the ice. This is really speculative, but this is the kind of language people are using now, talking about finding life with real optimism.
Beyond the solar system, the search for exoplanets is going very, very well. Virtually every star we survey we find planets! Well, that might be a bit of an exaggeration, but we’ve found hundreds and hundreds of planets. We’ve begun to see Earth-like planets and so the next step is to do spectroscopy to look at light passing through the atmospheres of those planets and look for signatures of elements like oxygen. Again, if you find oxygen-rich atmospheres — which we are on the verge of looking for now — if you find that, then you’ve got pretty good evidence there is life on those planets.
So, it could be we find life on a distant planet before we find life in the solar system, which would be tremendous. But really, I do think the big discoveries will be all about life, certainly in solar system exploration.
UT : What are your hopes for the future regarding physics, technology and space?
Large Hadron Collider (CERN/LHC/GridPP)
COX: I’d like to see an increase in rational thinking, which is synonymous with
scientific thinking.
Scientifically, the Large Hadron Collider is going to make a huge difference. It really is going to revolutionize our fundamental understanding of the way the universe works. Then there are these huge questions in fundamental physics, the question of why gravity is so weak, why the universe began in such an ordered way.
Then, what is 96% of the Universe made of? We know our Universe is full of something called Dark Matter and we don’t know what it is. The Universe is accelerating in its expansion, which we call Dark Energy and we don’t know what that is either. There is something fundamental going on.
I’d like to think this period of time is like the period of 1890 onwards to the turn of the 20th century. There were some small problems with things like understanding the spectrum of light, what atoms were; little problems really. But when we finally understood, it revolutionized our understanding of the Universe. Shortly after the turn of the century we got quantum theory, relativity – a complete change in our understanding. I’d like to think that maybe it’s a bit like that at the moment. There are so many little — and big — chinks in the armor of our picture of the Universe at the fundamental level. I think within the next few years, there will be big shifts, and probably, they will be led by the data from the LHC.
Brian Cox at CERN with Kevin Eldon and Simon Munnery. Photo by Gia Milinovich, courtesy Brian Cox
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At two separate conferences in July, particle physicists announced some provoking news about the Higgs boson, and while the Higgs has not yet been found, physicists are continuing to zero in on the elusive particle. Universe Today had the chance to talk with Professor Brian Cox about these latest findings, and he says that within six to twelve months, physicists should be able to make a definite statement about the existence of the Higgs particle. Cox is the Chair in Particle Physics at the University of Manchester, and works on the ATLAS experiment (A Toroidal LHC ApparatuS) at the Large Hadron Collider at CERN. But he’s also active in the popularization of science, specifically with his new television series and companion book, Wonders of the Universe, a follow up to the 2010 Peabody Award-winning series, Wonders of the Solar System.
Universe Today readers will have a chance to win a copy of the book, so stay tuned for more information on that. But today, enjoy the first of a three-part interview with Cox:
Universe Today: Can you tell us about your work with ATLAS and its potential for finding things like extra dimensions, the unification of forces or dark matter?
Brian Cox, during the filming of one of his television series. Image courtesy Brian Cox.
Brian Cox: The big question is the origin and mass of the universe. It is very, very important because it is not an end in itself. It is a fundamental part of Quantum Field Theory, which is our theory of three of the four forces of nature. So if you ask the question on the most basic level of how does the universe work, there are only two pillars of our understanding at the moment. There is Einstein’s Theory of General Relatively, which deals with gravity — the weakest force in the Universe that deals with the shape of space and time and all those things. But everything else – electromagnetism, the way the atomic nuclei works, the way molecules work, chemistry, all that – everything else is what’s called a Quantum Field Theory. Embedded in that is called the Standard Model of particle physics. And embedded in that is this mechanism for generating mass, and it’s just so fundamental. It’s not just kind of an interesting add-on, it’s right in the heart of the way the theory works.
So, understanding whether our current picture of the Universe is right — and if there is this thing called the Higgs mechanism or whether there is something else going on — is critical to our progress because it is built into that picture. There are hints in the data recently that maybe that mechanism is right. We have to be careful. It’s not a very scientific thing to say that we have hints. We have these thresholds for scientific discovery, and we have them for a reason, because you get these statistical flukes that appear in the data and when you get more data they go away again.
The statement from CERN now is that if they turn out to be more than just fluctuations, really, within six months we should be able to make some definite statement about the existence of the Higgs particle.
I think it is very important to emphasize that this is not just a lot of particle physicists looking for particles because that’s their job. It is the fundamental part of our understanding of three of the four forces of nature.
Brian Cox at Fermilab. Photo by Paul Olding.
UT : So these very interesting results from CERN and the Tevatron at Fermilab giving us hints about the Higgs, could you can talk little bit more about that and your take on the latest findings?
COX: The latest results were published in a set of conferences a few weeks ago and they are just under what is called the Three Sigma level. That is the way of assessing how significant the results are. The thing about all quantum theory and particle physics in general, is it is all statistical. If you do this a thousand times, then three times this should happen, and eight times that should happen. So it’s all statistics. As you know if you toss a coin, it can come up heads ten times, there is a probability for that to happen. It doesn’t mean the coin is weighted or there’s something wrong with it. That’s just how statistics is.
So there are intriguing hints that they have found something interesting. Both experiments at the Large Hadron Collider, the ATLAS and the Compact Muon Solenoid (CMS) recently reported “excess events” where there were more events than would be expected if the Higgs does not exist. It is about the right mass: we think the Higgs particle should be somewhere between about 120 and 150 gigaelectron volts [GeV—a unit of energy that is also a unit of mass, via E = mc2, where the speed of light, c, is set to a value of one] which is the expected mass range of the Higgs. These hints are around 140, so that’s good, it’s where it should be, and it is behaving in the way that it is predicted to by the theory. The theory also predicts how it should decay away, and what the probability should be, so all the data is that this is consistent with the so-called standard model Higgs.
But so far, these events are not consistently significant enough to make the call. It is important that the Tevatron has glimpsed it as well, but that has even a lower significance because that was low energy and not as many collisions there. So you’ve got to be scientific about things. There is a reason we have these barriers. These thresholds are to be cleared to claim discoveries. And we haven’t cleared it yet.
But it is fascinating. It’s the first time one of these rumors have been, you know, not just nonsense. It really is a genuine piece of exciting physics. But you have to be scientific about these things. It’s not that we know it is there and we’re just not going to announce it yet. It’s the statistics aren’t here yet to claim the discovery.
Brian Cox, while filming a BBC series in the Sahara. Image courtesy Brian Cox
UT : Well, my next question was going to be, what happens next? But maybe you can’t really answer that because all you can do is keep doing the research!
COX: The thing about the Higgs, it is so fundamentally embedded in quantum theory. You’ve got to explore it because it is one thing to see a hint of a new particle, but it’s another thing to understand how that particle behaves. There are lots of different ways the Higgs particles can behave and there are lots of different mechanisms.
There is a very popular theory called supersymmetry which also would explain dark matter, one of the great mysteries in astrophysics. There seems to be a lot of extra stuff in the Universe that is not behaving the way that particles of matter that we know of behave, and with five times more “stuff” as what makes up everything we can see in the Universe. We can’t see dark matter, but we see its gravitational influence. There are theories where we have a very strong candidate for that — a new kind of particle called a supersymmetry particles. There are five Higgs particles in them rather than one. So the next question is, if that is a Higgs-like particle that we’ve discovered, then what is it? How does it behave? How does it talk to the other particles?
And then there are a huge amount of questions. The Higgs theory as it is now doesn’t explain why the particles have the masses they do. It doesn’t explain why the top quark, which is the heaviest of the fundamental particles, is something like 180 times heavier than the proton. It’s a tiny point-like thing with no size but it’s 180 times the mass of a proton! That is heavier than some of the heaviest atomic nuclei!
Why? We don’t know.
I think it is correct to say there is a door that needs to be opened that has been closed in our understanding of the Universe for decades. It is so fundamental that we’ve got to open it before we can start answering these further questions, which are equally intriguing but we need this answered first.
UT: When we do get some of these questions answered, how is that going to change our outlook and the way that we do things, or perhaps the way YOU do things, anyway! Maybe not us regular folks…
COX: Well, I think it will – because this is part of THE fundamental theory of the forces of nature. So quantum theory in the past has given us an understanding, for example, of the way semiconductors work, and it underpins our understanding of modern technology, and the way chemistry works, the way that biological systems work – it’s all there. This is the theory that describes it all. I think having a radical shift and deepening in understanding of the basic laws of nature will change the way that physics proceeds in 21st century, without a doubt. It is that fundamental. So, who knows? At every paradigm shift in science, you never really could predict what it was going to do; but the history of science tells you that it did something quite remarkable.
There is a famous quote by Alexander Fleming, who discovered penicillin, who said that when he woke up on a certain September morning of 1928, he certainly didn’t expect to revolutionize modern medicine by discovering the world’s first antibiotic. He said that in hindsight, but he just discovered some mold, basically, but there it was.
But it was fundamental and that is the thing to emphasize.
Some of our theories, you look at them and wonder how we worked them! The answer is mathematically, the same way that Einstein came up with General Relativity, with mathematical predictions. It is remarkable we’ve been able to predict something so fundamental about the way that empty space behaves. We might turn out to be right.
Tomorrow: Part 2: The space exploration and hopes for the future
From a photon’s point of view, it is emitted and then instantaneously reabsorbed. This is true for a photon emitted in the core of the Sun, which might be reabsorbed after crossing a fraction of a millimetre’s distance. And it is equally true for a photon that, from our point of view, has travelled for over 13 billion years after being emitted from the surface of one of the universe’s first stars.
So it seems that not only does a photon not experience the passage of time, it does not experience the passage of distance either. But since you can’t move a massless consciousness at the speed of light in a vacuum, the real point of this thought experiment is to indicate that time and distance are just two apparently different aspects of the same thing.
If we attempt to achieve the speed of light, our clocks will slow relative to our point of origin and we will arrive at our destination quicker that we anticipate that we should – as though both the travel time and the distance have contracted.
Similarly, as we approach the surface of a massive object, our clocks will slow relative to a point of higher altitude – and we will arrive at the surface quicker than we might anticipate, as though time and distance contract progressively as we approach the surface.
Again, time and distance are just two aspects of the same thing, space-time, but we struggle to visualise this. We have evolved to see the world in snapshot moments, perhaps because a failure to scan the environment with every step we take might leave us open to attack by a predator.
Science advocates and skeptics say that we should accept the reality of evolution in the same way that we accept the reality of gravity – but actually this is a terrible analogy. Gravity is not real, it’s just our dumbed-down interpretation of space-time curvature.
If you could include the dimension of time in this picture you might get a rough idea of why things appear to accelerate towards a massive object - even though they do not themselves experience any acceleration.
Astronauts moving at a constant velocity through empty space feel weightless. Put a planet in their line of trajectory and they will continue to feel weightless right up until the moment they collide with its surface.
A person on the surface will watch them steadily accelerate from high altitude until that moment of collision. But such doomed astronauts will not themselves experience any such change to their velocity. After all, if they were accelerating, surely they would be pushed back into their seat as a consequence.
Nonetheless, the observer on the planet’s surface is not suffering from an optical illusion when they perceive a falling spacecraft accelerate. It’s just that they fail to acknowledge their particular context of having evolved on the surface of a massive object, where space-time is all scrunched up.
So they see the spacecraft move from an altitude where distance and time (i.e. space-time) is relatively smooth – down to the surface, where space-time (from the point of view of a high altitude observer) is relatively scrunched up. A surface dweller hence perceives that a falling object is experiencing acceleration and wrongly assumes that there must be a force involved.
As for evolution – there are fossils, vestigial organs and mitochondrial DNA. Get real.
Footnote:If you were falling into a black hole you would still not experience acceleration. However, your physical structure would be required to conform to the extremely scrunched up space-time that you move through – and spaghettification would result.
A recent prank involving the reenactment of a human sacrifice has got officials at CERN kind of miffed! Credit: CERN
[/caption]It’s a Higgs boson. No. We’re not talking about some swarthy seaman standing at the helm of a boat and keeping watch. We’re talking about a hypothetical massive elementary particle predicted to exist by the Standard Model of particle physics. Its presence is supposed to help explain our lack of consistences when it comes to theoretical physics – and observing it has been one of the prime functions of the Large Hadron Collider. But the LHC hasn’t found it yet. As a matter of fact, we might wonder just what else it hasn’t found…
Right now, scientists have answered – or at least postulated the answer to – some very ponderous questions that lay just beyond the scope of the standard model. One of the foremost is the existence of dark matter. To find the solution, they’re using a model called supersymmetry. It’s an easy enough concept, one that states for every particle a stronger one echoes it at higher energy levels. The only trouble with this theory is that there isn’t any proof of these “super-particles” to be found yet. “Squarks” and “gluinos”, the antithesis of quarks and gluons, have been canceled out at energies up to 1 teraelectronvolts (TeV) of the standard model, according to an analysis of the LHC’s first year of collisions.
It should be easy, shouldn’t it? Given the broad spectrum, there should be simple members found within the supersymmetric models – even leaving the more complex and energetic to be explored at another time. But “the air is getting thin for supersymmetry”, says Guido Tonelli of the LHC’s CMS collaboration. At the same time, there is no sign yet of gravitons – particles that transmit gravity and are essential for a quantum theory of the force – below an energy of 2 TeV.
This lack of findings is causing some folks to wonder if we’re expecting answers to the wrong questions, but Rolf-Dieter Heuer, CERN’s director general is more optimistic. He knows the LHC has only produced about 1/1000th of its eventual data. “Something will come,” he says. “We just have to be patient.” But what of the Higgs boson? So far it has only been a blip on the LHC screen. “We will have answered the Higgs’s Shakespeare question – to be or not to be – by the end of next year,” Heuer predicts.
When it comes to measurements, the everyday kind that deal with things like air pressure, tire pressure, blood pressure, etc., there is no such thing as an absolute accuracy. And yet, as with most things, scientists are able to come up with a relatively accurate way of gauging these things by measuring them relative to other things. When it comes to air pressure (say for example, inside a tire), this takes the form of measuring it relative to ambient air temperature, or a perfect vacuum. The latter case, where zero pressure is referred against a total vacuum, is known as Absolute Pressure. The name may seem slightly ironic, but since the comparison is against an environment in which there is no air pressure to speak of.
In the larger context of pressure measurement, Absolute Pressure is part of the “zero reference” trinity. This includes Absolute Pressure (AP), Gauge Pressure, and Differential Pressure. As already noted, AP is zero referenced against a perfect vacuum. This is the method of choice when measuring quantities where absolute values must be determined. Gauge Pressure, on the other hand, is referenced against ambient air pressure, and is used for conventional purposes such as measuring tire and blood pressure. Differential Pressure is quite simply the difference between the two points.
Cases where AP are used include atmospheric pressures readings: where one is trying to determine air pressure (expressed in units of atm’s, where one is equal to 101,325 Pa), Mean Sea Level pressure (the air pressure at sea level; on average: 101.325 kPa), or the boiling point of water (which varies based on elevation and differences in air pressure). Another instance of AP being the method of choice is with the measurement of deep vacuum pressures (aka. outer space) where absolute readings are needed since scientists are dealing with a near-total vacuum. Altimeter pressure is another instance, where air pressure is used to determine the altitude of an aircraft and absolute values are needed to ensure both accuracy and safety.
To produce an absolute pressure sensor, manufacturer will seal a high vacuum behind the sensing diaphragm. If the connection of an absolute pressure transmitter is open to the air, it will read the actual barometric pressure (which is roughly 14.7 PSI). This is different from most gauges, such as those used to measure tire pressure, in that such gauges are calibrated to take into account ambient air pressure (i.e. registering 14.7 PSI as zero).
We have written many articles about absolute pressure for Universe Today. Here’s an article about Boyle’s Law, and here’s an article about air density.
When operating at highest intensity, the NuMI beam line transports a package of 35,000 billion protons every two seconds to a graphite target. The target converts the protons into bursts of particles with exotic names such as kaons and pions. Like a beam of light emerging from a flashlight, the particles form a wide cone when leaving the target. A set of two special lenses, called horns (photo), is the key instrument to focus the beam and send it in the right direction. The beam particles decay and produce muon neutrinos, which travel in the same direction. Photo: Peter Ginter.
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Right when you thought that Fermilab was a thing of the past, new work with neutrinos are exciting us all over again. The scientists associated with the MINOS experiment at the Department of Energy’s Fermi National Accelerator Laboratory just announced their findings of a rare phenomena – the transformation of muon neutrinos into electron neutrinos.
On June 14 the Japanese T2K experiment also found clues to this type of transformation. These dual reports could have a profound impact on the way we understand how neutrinos impacted the evolution of our Universe. What burning question do the results answer? Try why there is more matter than anti-matter. If muon neutrinos transform into electron neutrinos, neutrinos could be the reason.
“The Main Injector Neutrino Oscillation Search (MINOS) at Fermilab recorded a total of 62 electron neutrino-like events. If muon neutrinos do not transform into electron neutrinos, then MINOS should have seen only 49 events.” says Fermilab. “The experiment should have seen 71 events if neutrinos transform as often as suggested by recent results from the Tokai-to-Kamioka (T2K) experiment in Japan.”
Using entirely different methods, the two neutrino experiments went to work. To measure the transformation of muon neutrinos into other neutrinos, the MINOS experiment sends a muon neutrino beam 450 miles (735 kilometers) through the Earth from the Main Injector accelerator at Fermilab to a 5,000-ton neutrino detector, located half a mile underground in the Soudan Underground Laboratory in northern Minnesota. The nearly twin detectors have different purposes. At Fermilab the purity of the muon neutrino beam is calibrated while Soudan detects electron and muon activity. It’s a fast trip, too…but just one four hundreths of a second is all it takes for these incredibly tiny particles to transform.
“Science usually proceeds in small steps rather than sudden, big discoveries, and this certainly has been true for neutrino research,” said Jenny Thomas from University College London, co-spokesperson for the MINOS experiment. “If the transformation from muon neutrinos to electron neutrinos occurs at a large enough rate, future experiments should find out whether nature has given us two light neutrinos and one heavy neutrino, or vice versa. This is really the next big thing in neutrino physics.”
An X-Wing fighter in space? Actually the ATV2 (Johannes Kepler) as it departs the ISS in 2011. Credit: NASA/Ron Garan
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What an amazing image! The ATV-2 Johannes Kepler looks like an X-Wing fighter from Star Wars as it departed from the International Space Station. Astronaut Ron Garan posted the image on his Twitpic page, asking viewers if they thought the spacecraft looked like the fictional fighter jets of the Alliance.
The ATV-2 left the ISS and entered Earth’s atmosphere on June 21. The spacecraft had a “blackbox” on board, a Re-Entry Breakup Recorder (REBR) to monitor temperature, acceleration, rotation rate, and other data as it tumbled and disintegrated through the atmosphere. The data was sent down via a “phone call” to an Iridium satellite to help scientists better understand the physics of what happens to a spacecraft when it breaks up on re-entry.
So, enjoy one last beautiful look at the ATV-2 in this stunning image.
You can follow Universe Today senior editor Nancy Atkinson on Twitter: @Nancy_A. Follow Universe Today for the latest space and astronomy news on Twitter @universetoday and on Facebook.
There are diminutive visitors to Earth. We’ve known about them and measured their presence since the 1960s. When the Sudbury Neutrino Observatory (SNO) turned on in May, 1999 the world became acutely aware of tiny particles known as solar neutrinos. The facility gathered data for seven years before shutting down and we’ve heard little in the media about neutrinos since. As we know, mass cannot be either created nor destroyed – only converted – so where did it originate? Exciting results produced by the international T2K neutrino experiment in Japan may be key to resolving this riddle.
To understand neutrinos is to understand their flavors: the electron neutrino teamed by particle interactions with electrons, and two additional marriages with the muon and tau leptons. Through research, science has proved these different types of neutrinos can spontaneously change into each other, a phenomenon called ‘neutrino oscillation’. From this action, two types of oscillations have been documented during the T2K experiment, but a new format has come to light… the introduction of electron neutrinos in a muon neutrino beam. This means neutrinos can fluctuate in every way science can possibly dream of. These new findings point to the fact that oscillations of neutrinos and their anti-particles (called anti-neutrinos) could be different. If they are, this could be an example of what physicists call CP violation. This would be a tidy explanation of why our Universe breaks the laws of physics by having more matter than anti-matter.
Unfortunately, the T2K neutrino experiment was disrupted by this year’s devastating Japan earthquake. But the team was prepared and both they – and the equipment – weathered the catastrophe. Before shutting down, six pristine electron neutrino events were recorded where there should have only been 1.5. With odds of this happening only one in one hundred times, the team felt these findings weren’t conclusive to confirm a new physics discovery and so they listed their results as an “indication”.
Prof Dave Wark of STFC and Imperial College London, who served for four years as the International Co-Spokesperson of the experiment and is head of the UK group, explains, “People sometimes think that scientific discoveries are like light switches that click from ‘off’ to ‘on’, but in reality it goes from ‘maybe’ to ‘probably’ to ‘almost certainly’ as you get more data. Right now we are somewhere between ‘probably’ and ‘almost certainly’.”
Prof Christos Touramanis from Liverpool University is the Project Manager for the UK contributions to T2K: “We have examined the near detectors and turned some of them back on, and everything that we have tried works pretty well. So far it looks like our earthquake engineering was good enough, but we never wanted to see it tested so thoroughly.”
Prof Takashi Kobayashi of the KEK Laboratory in Japan and spokesperson for the T2K experiment, said “It shows the power of our experimental design that with only 2% of our design data we are already the most sensitive experiment in the world for looking for this new type of oscillation.”
Key to the astronomical modeling process by which scientists attempt to understand our universe, is a comprehensive knowledge of the values making up these models. These are generally measured to exceptionally high confidence levels in laboratories. Astronomers then assume these constants are just that – constant. This generally seems to be a good assumption since models often produce mostly accurate pictures of our universe. But just to be sure, astronomers like to make sure these constants haven’t varied across space or time. Making sure, however, is a difficult challenge. Fortunately, a recent paper has suggested that we may be able to explore the fundamental masses of protons and electrons (or at least their ratio) by looking at the relatively common molecule of methanol.
The new report is based on the complex spectra of the methane molecule. In simple atoms, photons are generated from transitions between atomic orbitals since they have no other way to store and translate energy. But with molecules, the chemical bonds between the component atoms can store the energy in vibrational modes in much the same way masses connected to springs can vibrate. Additionally, molecules lack radial symmetry and can store energy by rotation. For this reason, the spectra of cool stars show far more absorption lines than hot ones since the cooler temperatures allow molecules to begin forming.
Many of these spectral features are present in the microwave portion of the spectra and some are extremely dependent on quantum mechanical effects which in turn depend on precise masses of the proton and electron. If those masses were to change, the position of some spectral lines would change as well. By comparing these variations to their expected positions, astronomers can gain valuable insights to how these fundamental values may change.
The primary difficulty is that, in the grand scheme of things, methanol (CH3OH) is rare since our universe is 98% hydrogen and helium. The last 2% is composed of every other element (with oxygen and carbon being the next most common). Thus, methanol is comprised of three of the four most common elements, but they have to find each other, to form the molecule in question. On top of that, they must also exist in the right temperature range; too hot and the molecule is broken apart; too cold and there’s not enough energy to cause emission for us to detect it. Due to the rarity of molecules with these conditions, you might expect that finding enough of it, especially across the galaxy or universe, would be challenging.
Fortunately, methanol is one of the few molecules which are prone to creating astronomical masers. Masers are the microwave equivalent of lasers in which a small input of light can cause a cascading effect in which it induces the molecules it strikes to also emit light at specific frequencies. This can greatly enhance the brightness of a cloud containing methanol, increasing the distance to which it could be readily detected.
By studying methanol masers within the Milky Way using this technique, the authors found that, if the ratio of the mass of an electron to that of a proton does change, it does so by less than three parts in one hundred million. Similar studies have also been conducted using ammonia as the tracer molecule (which can also form masers) and have come to similar conclusions.
Comic Microwave Background Courtesy of NASA / WMAP Science Team
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Not since the work of Fritz Zwicky has the astronomy world been so excited about the missing mass of the Universe. His evidence came from the orbital velocities of galaxies in clusters, rotational speeds, and gravitational lensing of background objects. Now there’s even more evidence that Zwicky was right as Australian student – Amelia Fraser-McKelvie – made another breakthrough in the world of astrophysics.
Working with a team at the Monash School of Physics, the 22-year-old undergraduate Aerospace Engineering/Science student conducted a targeted X-ray search for the hidden matter and within just three months made a very exciting discovery. Astrophysicists predicted the mass would be low in density, but high in temperature – approximately one million degrees Celsius. According to theory, the matter should have been observable at X-ray wavelengths and Amelia Fraser-McKelvie’s discovery has proved the prediction to be correct.
Dr Kevin Pimbblet from the School of Astrophysics explains: “It was thought from a theoretical viewpoint that there should be about double the amount of matter in the local Universe compared to what was observed. It was predicted that the majority of this missing mass should be located in large-scale cosmic structures called filaments – a bit like thick shoelaces.”
Up until this point in time, theories were based solely on numerical models, so Fraser-McKelvie’s observations represent a true break-through in determining just how much of this mass is caught in filamentary structure. “Most of the baryons in the Universe are thought to be contained within filaments of galaxies, but as yet, no single study has published the observed properties of a large sample of known filaments to determine typical physical characteristics such as temperature and electron density.” says Amelia. “We examine if a filament’s membership to a supercluster leads to an enhanced electron density as reported by Kull & Bohringer (1999). We suggest it remains unclear if supercluster membership causes such an enhancement.”
Still a year away from undertaking her Honors year (which she will complete under the supervision of Dr Pimbblet), Ms Fraser-McKelvie is being hailed as one of Australia’s most exciting young students… and we can see why!
