h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Sorry, this isn't really a question, rather an attempt to see whether or not I'm alone in being completely sceptical about one thing...

There have been various scaremongering reports about this thing, when it's turned on next week, creating a mini black hole and eating the earth... Now, forget about the probability of that particular problem, but, does anyone else find it even more improbable that the public 'switch-on' date is actually going to be the first time they try the thing out at full power?

Are the operators that daft as to risk the thing breaking down in front of every particle physicist in the world and half the world's media? Or have they quietly been running the thing for the last fortnight?

There is precedent for this...Calder Hall had been running quietly for 24 hours before the Queen pressed a big button to start it...

well, they've cut the low power tests so when switched on it will run at full whack from the get go. As to whether that is when they say it is- dunno.

Fascinating couple of programs on BBC 4 on it last night. Must be one of the first times in ages I've watched a whole programme start to finish without flicking around the channels. I wish there was stuff like that on telly.

What they will do on Wednesday is starting the actual collisions surely. The machine itself has probably been up and running for a while, and done various smaller things.

Depends what you mean by "Start".

I takes five weeks to cool the thing down to operating temperature, so they must have started a while back, and I would guess that every bit has already been tested in isolation somehow.

http://www.newscientist.com/channel/fundamentals/mg19926711.300-large-hadron-collider-the-wait-is-over.html

This article says the10th September is when the first protons start flying round the ring. It'll be another two more months until they get two beams colliding. They'll then run it at a warm-up collision energy of 10 TeV to calibrate their detectors up until new year, and won't achieve the maximum energy of 14 TeV until March 2009.

So, no black holes for a few months yet.

I guess the same would apply to Calder Hall - was the button to start up the cooling systems, the reactor itself, the generators or the connection to the grid?

Now who said physics wasn't cool?

http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/08/26/scirap126.xml

"and done various smaller things."

except, as i posted, they said they have cancelled the low energy runs and are going straight in with the full power ones.

the programme is here if you can wangle a way round the 'not uk' filtering:

http://www.bbc.co.uk/iplayer/episode/b00dccnr/

.. and what a helluva thing to be actually working on it!

I know - if only I'd studied harder at school. The guy presenting the show above and some of the bods in it, you really get a sense of their enthusiasm and excitement at doing this.

>> except, as i posted, they said they have cancelled the low energy runs and are going straight in with the full power ones. <<

http://www.lhc.ac.uk/latest-news.html

LHC's own site states they're starting off with 5TeV beams (which agrees with NS's 10TeV collisions), so they are not starting at full power.

Interesting. The CERN guy on the TV program said they had abandoned that idea. I guess the info on the programme from CERN is now out of date. Or the webpage is out of date. Either way we'll find out in a few days time.

As for the other question, from the site DB linked

"but the first attempt to circulate beams all the way around the LHC will be on the official start up day."

So yes, start up day will be the first full run of the system.

ah, looks like it was the programme out of date:

http://www.scientificblogging.com/big_science_gambles/lhc_start_up

"Seems they would even have skipped 5 TeV and gone straight to 7 TeV beams this fall, but as Evans said, the collider wasn't ready for the design energies, as some magnets had been lying around for two years,"

-------I guess the same would apply to Calder Hall - was the button to start up the cooling systems, the reactor itself, the generators or the connection to the grid? ------

Nope, all the button did on Calder Hall was to start a mockup dial showing the number of MegaWatts being shipped to the National Grid... It wasn't attached to anything else at all. They'd had the reactor up and running and attached to the National Grid the day before - They just had to wait for the queen to press the button before they could actually say they'd done it.

Put yourself in their situation as well... Everything's ready, tomorrow you're going to have loads of pressure on you to make sure it all works in public with all the bigwigs and press arriving in the morning...

It's 10 0'clock at night the day before the big event, there are just two of you in the office (the LHC is actually run by a team of two)... Wouldn't you press the buttons just to make sure it works?

whilst we're at it, I have two related questions that I probably won;t understand the answer to, but I'd be grateful to anyone who can answer them:

1) As the whole point of the LHC and so forth is lob particles around at high speed to get high energy collisions - why don't we just use naturally occurring events? I mean, there's all sorts of high energy particles whizzing about space and through our planet, such collisions must be happening all the time. So why build something like this? Is it simple a case of knowing when/where the collision will happen and being able to control that and the energy involved?

2) In the particle diagrams that result, you get a lot of tracks of particles whizzing out of the impact and then going into a decreasing spiral. Whether it be a big or a small spiral they seem to look the same. And at the end the trail stops. Why do they go in a spiral? And is the direction (clockwise/anticlockwise) significant?

I think naturally occuring events are no use because the fragments (ie the particles causing the spirals) wouldn't be detected. Either because they'd go in the wrong direction (hugely likely), or because the particles being looked for have very short half-lives and would decay before they hit a detector.

but surely the latter problem would be an issue in any collider, be it natural or man made?

I thought the detectors saw stuff that flew off in any direction?

The natural event are not high energy enough.

Even in ye-olde colliders such as at CERN I think they were getting to 70% or so of the energy of the big bang...

70% is my arbitrary number I get from remembering a graph I saw in a lecture once but it is certainly a significant proportion of it.

Even a supernova might not attain such energies.

Secondly, how do you analyse a collision taking place light years away with any precision?

Thirdly, you need to study these collisions in isolation to draw any reasonable conclusions.
Your suggestion I guess is like trying to analyse one molecular event in the middle of a raging fire...

Also, you need to know what you're looking at.

In a random event in space you've got no idea what sort of particle is colliding with another.
Energies and angles of collision can be precisely controlled too...



There are many reasons why I guess is what I'm saying.

A friend of mine visited CERN in March and attended a seminar about the LHC. During the Q&A bit at the end she asked the most awkward question possible: "What happens if there's a power cut?"

Apparently several of the CERN people started furiosuly scribbling notes and the reply was "Ahem. we have considered every eventuality."

I like the idea that some think this could destroy the world, and the scientists don´t want to wait around but just go straight for the big collision. Rather like the ones who thought the world´s first nuclear explosion would ignite the Earth´s atmosphere, and did it anyway.