### LHC vs. Shaving: which will destroy the universe first?

12Apr08

Today’s LA Times features the LHC on its online frontpage. The article, by John Johnson Jr (what a name!), interviews CERN-TH’s M. Mangano regarding the recent hubbub of universe-ending scenarios.

The usual problem with these discussions is that scientific honesty compels physicists to say that yes, environmental dangers are a non-zero but exceedingly small possibility. The public, however, doesn’t usually have a good sense of just how “exceedingly small” this possibility is. I was quite happy to find that Mangano made an effort to explain how unlikely this possibility is:

“Look,” Mangano said, leaning forward in his chair at CERN’s sprawling complex, “what if I told you tomorrow when you shave you will blow up the world? You laugh. You say that can’t happen. But how do you know?

“The only thing we know is that there have been about a million billion shaves since people started shaving and the world is still here,” he said. “So all we can say is the probability of you blowing up the world when you shave tomorrow is less than one in 1015.” [sic]

The online version makes the usual mistake of not properly translating the exponential $10^{15}$. This is a bit unfortunate since the largeness of this number is the punchline. However, I think the analogy that our everyday actions are only “safe” to certain probabilities really captures the essence of why the LHC isn’t dangerous.

#### 5 Responses to “LHC vs. Shaving: which will destroy the universe first?”

1. I read Robert Sawyer’s “Flash Forward”, a science fiction novel about the first time CERN used the LHC. It didn’t destroy the world, just pushed it 20 years into the future for about 40 seconds. It was an interesting book but nowhere near as disconcerting as shaving.

2. 2 Charles Tye

I think it depends on who is being shaved. Consider the barber who shaves all those who don’t shave themselves. Now, if anyone were to shave HIM, then the whole Universe would be at risk of disappearing in a puff of contradiction.

3. 3 Danny

I studied with someone called John Johnson at university. He was at St Johns College.