The Universe’s extra bits

source: CERN Bulletin

Parallel universes, unknown forms of matter, extra dimensions….This is not cheap science fiction but very concrete physics theories that the scientists are trying to confirm with the LHC and other ongoing experiments. Although it's enough to make us dream about going to a parallel world for the weekend, let’s keep our feet firmly on the ground and try to work out what all these things really are…

Given the astonishing fact that 96% of the Universe is actually unknown, we can think of filling it with all sorts of weird and exotic things. Extra dimensions and parallel universes may indeed be real, that is, their existence is accepted by a large community of scientists who have worked out mathematical models and physical constraints. “The idea of a fifth dimension was first introduced by Kaluza and Klein at the beginning of the last century in an attempt to unify gravity and electromagnetism”, confirms Ignatios Antoniadis from CERN’s Theory Group. “I personally got involved in the study of extra dimensions in the 1990s, when I was working at the Ecole Polytechnique in Paris”. 

Today, we know that extra dimensions could hide new forms of matter and energy as well as long-expected – yet undiscovered – particles, such as the graviton or the constituents of dark matter. Unfortunately, based on our current knowledge of Nature, scientists are not able to predict the exact number of possible extra dimensions. Some theoretical models allow for just one or two dimensions beside the four (three for space + time, according to Einstein’s relativity theory) that we experience every day, while the so-called string theories go as far as predicting the existence of 6 or more additional dimensions. “All the current theories that model the extra dimensions are equally valid and need to be tested with experiments”, says Antoniadis.

Scientists believe that there could be two different types of extra dimensions: one in which light can propagate (we will call it ‘electromagnetic’) and another in which light cannot propagate and with which we can only interact gravitationally (we will call it ‘gravitational’). Strictly speaking, the ‘electromagnetic’ type would still be part of our Universe as the type of interactions and the behaviour of light would be exactly the same. Therefore, parallel universes could only exist in ‘gravitational’ extra dimensions, those in which the photon cannot propagate.

The common feature of the two types of extra dimensions is that they must be finite and small, otherwise we would have already observed them. “The smaller the extra dimension, the higher the energy we need to probe it”, explains Antoniadis. “‘Gravitational’ extra dimensions could be much larger (up to almost a millimetre), because in this case the persisting lack of information we have about them could be due to the fact that our experimental apparatuses can only interact with these dimensions through gravitation, a very weak force at the particle scale in our dimensions”. 

The LHC is producing particle collisions at 7 TeV, a very high energy, which will even increase to 14 TeV after the long machine shutdown planned for 2012. Providing such a high energy to particles could enable them to enter the extra dimensions, interact and then return to our dimensions to enter the detector and leave a track that would carry the information of the travel. “Both types of extra dimensions can potentially be probed by experiments at the LHC”, confirms Antoniadis. “The high-energy proton-proton collisions could produce gravitons that would travel not only in our dimensions but also in possible extra ones. In the gravitational type of extra dimensions, the strength of gravitation would be much higher than in ours and therefore the graviton would most likely disappear from our dimensions and stay in the extra ones. This would result in some missing energy– carried by the escaping graviton – in the detectors. This missing energy would be associated with other specific features and characteristic bits of information that would uniquely identify it as an escaped graviton. As for the ‘electromagnetic’ types of extra dimensions, they could be probed even more directly because particles can enter them very shortly, leaving a clear signal in our detectors that would directly confirm their existence.”

For the first time, the LHC experiments are collecting data at energies that can potentially enable scientists to probe extra dimensions. However, before booking our trip to the closest parallel universe, let’s allow a couple of more years for their data analysis to provide us with conclusive results!

by CERN Bulletin

Cern's Large Hadron Collider makes first collisions

By Paul Rincon, Science reporter, BBC News

Engineers operating the Large Hadron Collider (LHC) have smashed together proton beams in the machine for the very first time.

The low-energy collisions came after researchers circulated two beams simultaneously in the LHC's 27km-long tunnel earlier on Monday.

Cern's director of communications, Dr James Gillies, said the first collisions had taken place just as a news conference was under way on Monday to discuss progress following the machine's restart at the weekend.

"We didn't have time to analyse them then. We waited until all four of the (detectors) had seen good candidates (for collisions)," he told BBC News.

The spokesperson for the Alice experiment, Jurgen Schukraft, said cheers erupted with the first collisions.

"This is simply tremendous," he said.

Engineers restarted the LHC on Friday evening after a 14-month hiatus while the machine was being repaired.

It had to be shut down shortly after its inauguration when an electrical fault led to magnets being damaged and to one tonne of liquid helium leaking into the tunnel.

Particle beams injected into LHC for first time since September 2008

Engineers working on the Large Hadron Collider (LHC) have successfully injected beams of particles into two sections of the vast machine.

An LHC spokesperson said this was the first time particle beams had been inside the LHC since it was shut down late in September 2008.

Scientists working on the giant particle accelerator described the success as "a milestone".

They plan to circulate a beam around the 27km-long tunnel in November.

On 23 and 25 October, beams of protons and of lead ions were injected into the LHC ring, and successfully guided both clockwise and anti-clockwise through two of the eight sectors. Each sector is approximately 3.5km long.

The extreme cold allows the magnets inside the LHC, which align and accelerate the beam, to become "superconducting". This means they channel electric current with zero resistance and very little power loss.

The Big Bang, the LHC and the Evolution of the Creation of the Universe by Brian Cox

In "There's probably no God, the Atheists Guide to Christmas" edited by Ariane Sherine, Brian Cox has a chapter on the Big Bang titled "The Large Hadron Collider: A scientific creation story".

The LHC recreates the conditions of the universe less than a billionth of a second after the big bang. The job of the LHC is too study the universe during the time when the Higgs particles are thought to have been generated. The history of the universe is thus:

• 13.7 billion years ago universe begins (t=0)
• gravity separates from the other forces of nature (t+10-43 seconds)
• exponential expansion of universe (t+10-36 s)
• from size of electron to size of melon (t+10-32 s)
• with formation of sub-atomic particles
• and Higgs field (t+10-12 s)
• gives mass to sub-atomic particles
• Higgs acts like cosmic treacle
• if Higgs particles aka Higgs Boson, aka The God Particle (Leon Lederman) exist (after 40 years we don't know) then Higgs Boson must be created in LHC (Standard Model)
• Higgs particles decays too quickly to be seen even in LHC 
• but Muon will be seen from decay of Higgs particle 
• Higgs Boson is tens or hundreds of times heavier than the protons that were smashed together (mini big bang) to create it (E=mc2). Energy=mass
• because Higgs particles are light enough to show up in LHC
• if Higgs particles are NOT found in LHC 
• some other mechanism (Minimally Supersymetric Standard Model?) will show up in LHC which creates mass
• and explains Dark Matter

After t+10-12 s time we already know what happened to the universe because smaller cousins to LHC (eg Fermilab Tevatron?) have been working for decades:-

• 4 forces of nature (strong nuclear, electromagnetic, weak, gravity) formed (t+10-6 s)
• strong nuclear force
• binds quarks together in nucleus of atom
• electromagnetism
• holds electrons in place around nucleus
• weak force
• allows sun to shine, explains radioactive decay
• gravity
• is missing from Standard model
• creates infinities when gravity is added 
• if treat particles as tiny points, when they come infinitely close together, gravity becomes infinitely strong 
• by treating particles as strings (not tiny points) we have a way for gravity to work
• but gravity is included in Einstein's General Relativity
• a Theory of Everything would combine Standard model with General Relativity
• String Theory combines all particles and forces (and makes a decent cup of coffee!)
• quarks and leptons interact
• quarks stick together to give protons & neutrons, neutrinos roam universe (t+1 s)
• protons & neutrons form elements (t+3 minutes)
• Hydrogen 75% : Helium 25% ratio fixed (t+30 m)
• Light as Photons set free from dense universe: cosmic microwave background (t+ 380,000 years)
• gravity collapses H & He to form stars
• 4 forces of nature interact: x3 He fuse to give Carbon
• more fusions give oxygen and other light elements
• stars run out of fuel, explode 
• scattering C & Oxygen & other light elements
• creating Gold, Silver & other heavy elements
• gravity forms stars & dense rocky planets orbit
• on at least one planet, occurs self replication & life & us!

Additional material added above from the 5 YouTube videos:-

This work by crabsallover is licensed under a Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales License.

Talks Brian Cox: What went wrong at the LHC

CERN on YouTube

Final LHC magnet goes underground

A quadrupole magnet in the LHC tunnel

Geneva, 30 April 2009. The 53^rd and final replacement magnet for CERN's Large Hadron Collider (LHC) was lowered into the accelerator's tunnel today, marking the end of repair work above ground following the incident in September last year that brought LHC operations to a halt. Underground, the magnets are being interconnected, and new systems installed to prevent similar incidents happening again.

The LHC is scheduled to restart in the autumn, and to run continuously until sufficient data have been accumulated for the LHC experiments to announce their first results.

"This is an important milestone in the repair process," said CERN's Director for Accelerators and Technology, Steve Myers. "It gets us close to where we were before the incident, and allows us to concentrate our efforts on installing the systems that will ensure a similar incident won't happen again."

The final magnet, a quadrupole designed to focus the beam, was lowered this afternoon and has started its journey to Sector 3-4, scene of the September incident. With all the magnets now underground, work in the tunnel will focus on connecting the magnets together and installing new safety systems, while on the surface, teams will shift their attention to replenishing the LHC's supply of spare magnets.

In total 53 magnets were removed from Sector 3-4. Sixteen that sustained minimal damage were refurbished and put back into the tunnel. The remaining 37 were replaced by spares and will themselves be refurbished to provide spares for the future.

"Now we will split our team into two parts," explained Lucio Rossi, Deputy head of CERN's Technology Department. "The main group will carry out interconnection work in the tunnel while a second will rebuild our stock of spare magnets."

The LHC repair process can be divided into three parts. Firstly, the repair itself, which is nearing completion with the installation of the last magnet today. Secondly, systems are being installed to monitor the LHC closely and ensure that similar incidents to that of last September cannot happen again. This work will continue into the summer. Finally, extra pressure relief valves are being installed to release helium in a safe and controlled manner should there be leaks inside the LHC's cryostat at any time in the machine's projected 15-20 year operational lifetime.

CERN is publishing regular updates on the LHC in its internal Bulletin, available at www.cern.ch/bulletin, as well as via twitter and YouTube at www.twitter.com/cern and www.youtube.com/cern

Hadron Collider repairs cost £14m

Repairing the Large Hadron Collider (LHC) near Geneva will cost almost £14m ($21m) and "realistically" take until at least next summer to start back up.

An electrical failure shut the £3.6bn ($6.6bn) machine down in September.
The European Organization for Nuclear Research (Cern) thought it would only be out of action until November but the damage was worse than expected.
It is hoped repairs will be completed by May or early June with the machine restarted at the end of June or later.
Cern spokesman James Gillies said: "If we can do it sooner, all well and good. But I think we can do it realistically (in) early summer."

The fault occurred just nine days after it was turned on with Cern blaming the shutdown on the failure of a single, badly soldered electrical connection in one of its super-cooled magnet sections.
The collider operates at temperatures colder than outer space for maximum efficiency and experts needed to gradually warm the damaged section to assess it.
"Now the sector is warm so they are able to go in and physically look at each of the interconnections," Mr Gillies told Associated Press.

The LHC: broken, but officially inaugurated with rhymes

Kate McAlpine (aka LHC rapper AlpineKat) writes:

CERN released a technical report last week, detailing the causes of the most recent Large Hadron Collider delays  but that didn't stop the 21 October start-up celebration - "LHC Fest" - from staying on schedule.

Following the unexpected success of the Large Hadron Rap - 3.6 million views and counting - I seem to have become something of a regular at CERN functions, alongside Les Horribles Cernettes - the subject of the first ever photograph on the web - and the Cannettes Blues Band. But sadly, most of my original backup crew has left CERN, so we've had different personnel each time.

During the hi-fives all around at the end of the performance, Lizzie Gibney, a dancer in the original video and on backing vocals last night, put it best with: "Give me some skin, Lyn!"

Hadron Collider halted for months

The Large Hadron Collider near Geneva will be out of action for at least two months, the European Organization for Nuclear Research (Cern) says.

Part of the giant physics experiment was turned off for the weekend while engineers probed a magnet failure.

But a Cern spokesman said damage to the £3.6bn ($6.6bn) particle accelerator was worse than anticipated.

Section damaged

On Friday, a failure, known as a quench, caused around 100 of the LHC's super-cooled magnets to heat up by as much as 100C.

The fire brigade were called out after a tonne of liquid helium leaked into the tunnel at Cern, near Geneva.

Cern spokesman James Gillies said on Saturday that the sector that was damaged would have to be warmed up to above its operating temperature - of near absolute zero - so that repairs could be made, and then cooled down again.

While he said there was never any danger to the public, Mr Gillies admitted that the breakdown would be costly.

He said: "A full investigation is still under way but the most likely cause seems to be a faulty electrical connection between two of the magnets which probably melted, leading to a mechanical failure.

"We're investigating and we can't really say more than that now.

"But we do know that we will have to warm the machine up, make the repair, cool it down, and that's what brings you to two months of downtime for the LHC."

Setback

The first beams were fired successfully around the accelerator's 27km (16.7 miles) underground ring over a week ago.

The crucial next step is to collide those beams head on. However, the fault appears to have ruled out any chance of these experiments taking place for the next two months at least.