First Post of the Year – First New Science from the LHC

The Large Hadron Collider has been running for over a year now and scientists have a massive amount of data to go through.

So far they have been looking for things we already know about, just to check the thing is working properly.

Now they have started looking for new Physics – in this case trying to work out why the antimatter and matter created at the Big Bang did not cancel each other out. 1 particle in billions of billions got left behind.

LHCb, the detector looking for the beauty quark has noticed that the matter and antimatter quarks are decaying in different ways.

You can see the red curve is different for matter B particles (left graph) and antimatter B particles (right graph). This extra time might be the reason why more matter existed than antimatter after the universe had started expanding.

At the moment the data is mostly certain (sigma 3.5) – we need a sigma of 5 for a formal discovery to be published. Sigma is a measure  standard deviation, the likelihood of the results being by chance.

  • Particle physics has an accepted definition for a “discovery”: a five-sigma level of certainty
  • The number of standard deviations, or sigmas, is a measure of how unlikely it is that an experimental result is simply down to chance rather than a real effect
  • Similarly, tossing a coin and getting a number of heads in a row may just be chance, rather than a sign of a “loaded” coin
  • The “three sigma” level represents about the same likelihood of tossing more than eight heads in a row
  • Five sigma, on the other hand, would correspond to tossing more than 20 in a row
  • A five-sigma result is highly unlikely to happen by chance, and thus an experimental result becomes an accepted discovery
Mr G

Do we understand risk?

Risk, uncertainty, reliability, correlation, relationship, causality….

All very important words to a scientist. They help us explain what our results mean and how we can compare our results and the results of others.

But does the public understand in the same way? This question formed a large chunk of my Masters of Science course when we looked at science communication.

This BBC article sums up the issue quite well (pity it wasn’t around last year… it would have been useful to quote from…) It was triggered by the latest OTT writing about mobile phones and cancer…

Does not knowing something for certain (what ever “certain” is) make us more worried or less worried?

The problem we have (as the public and the scientists) is that lack of evidence FOR a link between things does not mean evidence AGAINST a link (though if 2000 experiments said “no” we get fairly well convinced) – this Digital Lifestyles article from  2 008 sums up the evidence – but notice the “hedging of bets” in the very last sentence…

Mr G

Sources – BBC News, Digital Lifestyles