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Zidbits – Learn something new everyday! | August 23, 2014

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Student Finds Universe’s Missing Mass

Student Finds Universe’s Missing Mass

Not to be confused with dark matter, baryonic matter (the stuff that makes up the visible ‘normal’ matter in the universe) was – until recently – in short supply in our universe. Half of it was missing.

A student at Monash University has made a breakthrough in the field of astrophysics, discovering what – until now – has been referred to as the Universe’s “missing mass”. During a three month targeted X-ray search for the missing matter, Amelia Fraser-McKelvie and her team at the Monash School of Physics, found it – or at least some of it.

The Student’s Surprising Discovery

What makes this discovery more noteworthy is the fact that Ms. Fraser-McKelvie isn’t a career researcher, or even studying at a postgraduate level. She is a 22-year-old undergraduate Aerospace Engineering/Science student who discovered the missing mass during her summer scholarship, working with two astrophysicists at the School of Physics, Dr Jasmina Lazendic-Galloway and Dr Kevin Pimbblet.

Monash’s School of Physics put out a request for students who were interested in a 6-week paid astrophysics internship during a vacation period, and chose Ms Fraser-McKelvie from a large pool of applicants. Dr Pimbblet, a lecturer in the School of Physics, put the magnitude of the discovery in context by explaining that scientists had been hunting for this missing baryonic matter for decades.

The Universe’s Missing Mass

galaxy filaments“From a theoretical viewpoint, it was thought that there should be about double the amount of matter in the local Universe compared to what we observed. It was predicted that most of this missing mass should be located in large-scale cosmic structures called filaments – a bit like thick shoelaces,” said Dr Pimbblet.

Astrophysicists also predicted that the matter would be low in density, but high in temperature – approximately one million degrees Celsius. This meant that the matter should have been observable in the X-ray spectrum. Amelia Fraser-McKelvie’s discovery proved that prediction correct.

How It Was Found

Ms Fraser-McKelvie said the ‘Eureka moment’ came when Dr Lazendic-Galloway closely examined the data they had collected. “Using her expert knowledge in the X-ray astronomy field, Jasmina re-analyzed our results to find that we had in fact detected the filaments in the results, where previously we believed we had not.”

X-ray observations provide important information about the physical properties of large-scale structures, which can help astrophysicists understand their true nature. Until now, they had been making deductions based only on numerical models, so the discovery is a huge leap forward in determining how much matter is actually contained in those filaments.

A Bright Future

Still a year away from undertaking her Honors (which she will complete under Dr Pimbblet’s supervision), Ms Fraser-McKelvie is being called one of Australia’s most exciting young students. She has now been published in one of the world’s oldest and most prestigious scientific journals, Monthly Notices of the Royal Astronomical Society.

Amelia Fraser-McKelvie and team“Being a published author is exciting for me, and it’s something I could never have done without the help of both Jasmina and Kevin. Their commitment and passion for this project ensured the great results and I am extremely thankful to them for all the help they have given me and time they have invested,” said Ms Fraser-McKelvie.

Dr Pimbblet said that he had under his tuition a very talented student who excelled in performing the breakthrough research.

“She has managed to get a refereed publication accepted by one of the highest ranking astronomy journals in the world as a result of her endeavors. I cannot underscore enough what an amazing achievement this is. We will use this research as a science driver for future telescopes that are being planned, such as the Australian Square Kilometer Array Pathfinder, which will be built in Western Australian.”

Provided by Monash University
The paper can be found at arxiv.org’s website.

Comments

  1. Robert Ackerman

    From I understand, it is possible to go faster than the speed of light. I not a scientist or a physicist but it does interest me. I’ve watched and read the information but don’t understand exactly what it means, but if there is a kind of wave or wormhole could this have something to do with it?

    • Bryan Oswald

      It is not possible to travel faster than the speed of light. At least, according to our current understanding of the universe. Einstein said that doing so would violate the causality principle. The causality principle is essentially the relationship between cause and effect: first there is a cause, which causes the effect. The speed of light, also according to Einstein, is ‘the speed limit of the universe’. This is because nothing, no particles, forces, or anything else, can travel faster than the speed of light.

      Let’s suppose for a second that you could move faster than the speed of light. Let’s say you also have a long stick. Let’s say you took this long stick and knocked over a domino. You immediately ran over to the domino, at a speed faster than the speed of light. You could then knock over the domino with your hand, before it gets knocked over by the stick. This is why moving faster than the speed of light violates causality. Essentially, effects would happen before their causes.

      In addition, according to Einstein’s principle of relativity, objects become heavier as they increase their speed. As an object approaches the speed of light, it becomes infinitely heavy. Because force = mass * acceleration, an infinite mass would require an infinite force to accelerate it to the speed of light. This means that there is not enough energy in the entire universe to move even a small object at the speed of light.

      Now, there are some exceptions. One is something called cherenkov radiation, but it’s kind of cheating because the particles emitted are moving faster than protons which are moving at a reduced speed. So the radioactive particles move faster than those particular light particles are moving, but not faster than the true speed of light, the constant c (c = 299,792,458 meters per second).

      The other exception, and this would be the ‘wave or wormhole’ that you mentioned, is something called a warp drive. This one is also a bit of a cheat, besides still being entirely theoretical, because it avoids anything actually moving at a speed faster than c. The idea is that you actually manipulate the fabric of space-time, creating a ‘wave’ in the physical dimension of space. The idea is to create a sort of bubble, in which space-time is normal, then create a ‘trough’ in front of the bubble and a ‘crest’ behind it (I used quotes around trough and crest because the wave in space would not actually resemble a wave in the ocean, with a high point and low point. Instead, it would look more like a sound wave(which are often represented as having troughs and crests, as an easier method of visualization) with points of high and low pressure. The trough is equivalent to the point of low pressure, and the crest is the point of high pressure). As this wave propagates forward, it carries whatever is inside the bubble with it. The wave moves due to the pressure fields in the wave. As the pressure attempts to equalize with the space around it, the low pressure pulls space forward, and the high pressure pushes space in the same direction. If you were able to create a wave which propagates faster than the speed of light, then you would be able to ‘ride’ the wave, achieving travel at faster than light speeds without ever actually moving at all through space, as you are sitting stationary inside this bubble of space that moves forward.
      Wormholes are not actually related to this idea, but they are an example of the manipulation of space-time. In theory, a wormhole occurs when space-time is bent to the point that two non adjacent parts of it touch. Imagine folding a blanket in half, when you touch one end to the other, you connect two points that are on opposite sides of the blanket. The thing is, actually bending space this much takes an incredible amount of energy, and wormholes are theorized to happen at black holes, where a huge amount mass has been compressed to a point so incredibly dense that the gravity of this mass actually bends space around itself.

      This is also the main problem with creating a warp drive. It would require almost inconceivable amounts of energy to accomplish, not to mention that currently, we don’t know of any way to manipulate space with enough precision to create the wave and bubble effect necessary for this to work.

      Hope this helps, and if you want more info this site also has a page about both why nothing can move faster than light and about warp drives. And it probably has one about wormholes too, though I haven’t checked.

  2. Brian

    Positrons and electrons produced by terrestrial gamma-ray flashes. This is gamma evolving.

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