This needs extreme care before getting to excited.
Yes we are all expecting to see gravity waves and due to that, the experiment has a testing protocol.
The full rumour is they saw the predicted chirp of two black holes merging. Such an observation means not only direct observation of gravity waves but direct evidence of black holes and the ability to merge
http://phys.org/news/2015-09-black-holes-collide.htmlHowever good scientists are wary they don't fool themselves.
A team of three collaboration members has the ability to simulate a detection by using actuators to move the mirrors. “Only they know if, and when, a certain type of signal has been injected,” says Laura Cadonati, a physicist at the Georgia Institute of Technology in Atlanta who leads the Advanced LIGO’s data-analysis team.
Two such exercises took place during earlier science runs of LIGO, one in 2007 and one in 2010. Harry Collins, a sociologist of science at Cardiff University, UK, was there to document them (and has written books about it1). He says that the exercises can be valuable for rehearsing the analysis techniques that will be needed when a real event occurs. But the practice can also be a drain on the team’s energies. “Analysing one of these events can be enormously time consuming,” he says. “At some point, it damages their home life.”
The original blind-injection exercises took 18 months and 6 months respectively. The first one was discarded, but in the second case, the collaboration wrote a paper and held a vote to decide whether they would make an announcement. Only then did the blind-injection team ‘open the envelope’ and reveal that the events had been staged.
Whoever tweeted it broke protocol because this could be nothing more than a test. As you can see the analysis will take a couple of months before even the staff are told if it was a test or not.
This is one of those experiments where there is no easy background test open to it so "blind injection" protocol.
The result being in the category almost too good to believe has many guessing it was a test. However it will be massive if the result rumour is correct.
Watching all the crackpots either deny such a result or try to invent some reason their theory predicted it will be funny. Even on this forum there will be a couple with explaining to do
