What a fantastic start for July 2012!
First you have the 5 Sigma confirmation for the elusive 'Higgs Boson' aka 'God Particle', a label that most scientists actually dislike, on the 5th of July.
Then you have the first time a Dark Matter filament has been convincingly detected from its gravitational lensing effect, on the 4th of July!
The Higgs Boson
The problem with the detecting the Higgs Boson is the amount of noise that needs to be filtered our from the data collected from the Large hadron Collider (LHC) at CERN, Geneva.
The LHC highlighted, with a few of it's detectors
One way to put it into perspective is to imagine you mixed a specially coloured grain of sand into a bucket full of normal sand and then throwing the whole bucket into the air. Try picking out your coloured grain out in the air from that mess. Makes finding a needle in a haystack look like a walk in the park.
The best part is this: the Higgs Boson itself isn't observed. The particles created after 2 protons are accelerated to sub-light speeds and smashed into each other are so volatile that they only exist for tiny fraction of a second before decaying. So, what the scientists do is to look for decay signatures that point to the Boson itself.
Because they have to scrub through so much noise in the data, scientists use statistics to make sure that the data they have definitive and not a fluke. A 5 Sigma confirmation means that there's only 1 in 3 million chance that it was a random occurance. So while not, 100% confirmed, it's essentially 99.999997% confirmed.
Why is this important?
The Higgs Boson was predicted when scientists realise that, in the Standard Model of Particle Physics, if everything else, like electrons, protons and quarks, had their own mass, the equations didn't work. It worked only when mass was treated something not already present in particles, but a property that was 'given' by the existence of another particle. It's kinda like there's weight only when there's gravity.
But if that's the case, then is it possible that the model itself is broken? Maybe, but then it explained everything else very precisely and accurately up to this point, so they figured that the Higgs Boson must be true as well.
If the Higgs Boson was not found, then it would mean that the Standard Model of Particle Physics is fundamentally flawed. The discovery vindicates the Standard Model, allowing scientists to confidently move on to other discoveries with a solid foundation of Particle Physics that's proven to work.
Yet, Some Say It's a Bittersweet Discovery?
That's because most huge discoveries are borne through unexpected results. Also, the Standard Model only explains physics on the micro level, but does not factor in other important properties like gravity, another important component of the universe.
There are many scientists who were actually hoping for a totally unexpected outcome that might lead to new discoveries instead of simply confirming an existing prediction.
Dark Matter Bridges
Dark matter, is essentially matter that we know nothing about, except that it exists. Yet, scientists calculated that all the matter that we know of, like stars, galaxies and molecular clouds, only make up about 15% of the total matter available. The other 85% is unknown, doesn't interact easily with known matter and doesn't give off light, hence the term 'Dark Matter'.
Dark matter however, does effect gravity and at spots where gravity is concentrated, gravitational lensing can occur. Like how water distorts light as it passes through it when viewed from the outside, dense spots of gravity can bend light passing through it. Scientists can use this to measure the amount of gravity and therefore, the amount of matter present in that area.
Most scientists think that it wasn't possible to seriously search for dark matter until telescopes become more sensitive but thankfully, due to the unique positioning of galaxies Abell 222 and Abell 223, they were able to observe very weak levels of gravitional lensing between them, pointing the the existence to a bridge of dark matter, or 'filament', between the 2 galaxies.
These Dark Matter Filaments are thought to hold groups of galaxies together is groups called 'clusters' and they have never been able to truly infer its existence, until now.
What a great start to July 2012!
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