This geocache series was placed on occasion of the 10th anniversary of the discovery of the Higgs boson. We want to show you the beautiful countryside around the CERN Meyrin site and tell the story of this discovery with this Geocache series containing of five traditionals.
Each Geocache is dedicated to a particular aspect of the 50-year long scientific journey. The following Caches belong to this series:
The topic of this geocache is:
What is it what we call a "discovery" in particle physics? A short introduction into Statistics and Big Data
So, in 2012 the Higgs Boson was discovered. But what exactly does "discovery" in particle physics mean?
Scientists use a statistical hypothesis-testing framework to determine which of two hypotheses is consistent with the data they collect in experiments. For example, hypothesis one (also called the null hypothesis) could be “The Higgs boson does not exist” and hypothesis two (also called the alternative hypothesis) could be “The Higgs boson does exist”.
After collecting data, scientists calculate the probability that they would see a signal that is at least as strong as the one their data shows, while assuming that the null hypothesis is correct. For example, particle physicists calculated the probability that their data would show a signal consistent with that of the Higgs boson even if the Higgs boson did not exist - purely because of statistical fluctuations. It is important to note that this probability is not the probability that the null model is true.
If this probability is very small, the null hypothesis is rejected in favour of the alternative hypothesis. What does “very small” mean? It depends on the field of science. In many fields, a probability below 5% would be small enough to reject the null model. In particle physics however, a much stricter standard has been developed over the past 50 years. This standard is called “5 sigma”. 5 sigma corresponds to a tiny probability of 3*10^-5%, a chance of 1 in 3.5 million, that a signal in the data is only caused by statistical fluctuations. In particle physics, journals now only accept articles claiming a discovery if the 5 sigma standard is met.