Posted on 06/09/2003 6:11:13 AM PDT by andy224
Atlas holds key to scientists' map of Universe By Mark Henderson A vast cavern is the stage for tests to find the 'God particle'
SCIENTISTS have taken a step closer to finding the “God particle” that is thought to shape the Universe. In a concrete cavern 130ft deep and bigger than the nave of Canterbury Cathedral, they will mimic the high-energy conditions that existed fractions of a second after the Big Bang to study a beam of energy a quarter of the thickness of a human hair.
The vast Atlas cavern, which was completed last week at Cern, the European nuclear physics laboratory on the Franco-Swiss border, will house parts of a giant atom-smasher that is expected to solve the most elusive riddle in physics.
When the £1.5 billion Large Hadron Collider (LHC) is switched on in 2007, it will determine once and for all whether the Higgs boson, a mysterious fundamental particle held to give matter its mass, really exists. If the machine finds the boson, proposed by Professor Peter Higgs of Edinburgh University in 1964, it will prove that the Standard Model for the nature of the Universe is correct. If not, the maxims of modern physics will be thrown into disarray.
The boson was nicknamed the “God particle” by the Nobel laureate Leon Lederman for its centrality to the cosmos. Although it will be so small that its presence can only be calculated, not seen, the search for it requires some of the largest and most advanced scientific instruments designed.
The LHC itself is a ring 17 miles (27km) in circumference, buried up to 100m (330ft) underground, through which streams of protons will be bent by the world’s most powerful magnets and smashed into each other at close to the speed of light.
The new cavern, which will house the Atlas detector for tracking the Higgs and other particles, is 40m (130ft) deep, 55m (180ft) long and 35m (115ft) wide.
However, the proton beam that runs through both devices measures just 10 microns in diameter: less than a quarter of the thickness of the average human hair. Roger Cashmore, a British physicist and Cern’s director of research, said: “It is an astonishing feat of engineering. The consultants were on the verge of saying it was impossible to build. But the Atlas cavern is finished, the biggest of its kind in the world, and these experiments are going to tell us whether we’re right about the Universe.”
The current best guide to the nature of the Universe is the Standard Model, an elegant theory that describes how most particles and forces interact. The Higgs boson is its missing keystone: without it, there is no good explanation for why matter has mass and therefore exists.
According to the theory, the Universe is permeated by a field of Higgs bosons, which consist of mass but very little else. As particles move through the field, they interact with it like a ball dropped into a tub of treacle, getting slower, stickier and heavier. Their ultimate mass depends on the strength of the interaction.
Though mathematics predicts its existence, the Higgs boson has never been detected. It is so heavy that the biggest atom-smashers, Cern’s Large Electron-Positron collider (LEP) and the Tevatron at Fermilab in Illinois, have been unable to generate the high energy collisions needed to reveal it, although they have found hints that it is probably there. This is where the LHC comes in. It is 70 times as powerful as the LEP and seven times stronger than the Tevatron, covering all the energy values at which the Higgs might exist. If it is there, it will find it.
What is more, if the “God particle” proves to be a false deity, the LHC will unlock the secret of what is out there instead. “If it doesn’t find the Higgs, it will find what substitutes for it,” Dr Cashmore said.
Jim Virdee, Professor of Physics at Imperial College, London, and a leading Cern researcher, said: “There has to be something else, beyond what we have found already, that explains mass. We believe it’s the Higgs, but Nature may be smarter than us. Either way, the results will tell us what is the right road.”
The atom-smasher will accelerate protons so close to the speed of light that they become 7,000 times heavier than normal. The beams are bent into a circle by superconducting magnets, cooled by liquid helium at -271.4C, almost a degree colder than outer space.
When the protons collide, they are destroyed in a huge burst of energy. This energy coalesces into very heavy particles, one of which scientists hope will be the Higgs.
As the boson is unstable, it will quickly decay, scattering a characteristic signature of smaller particles and energy. These will be picked up by the LHC’s eyes — the Atlas and a sister detector — which surround the collision points.
The detectors, which stand 22m (72ft) and 15m (49ft) tall respectively, are “giant microscopes” built like onions, with several layers of instruments that track particles and measure energy.
The experiments will generate enormous quantities of data, much of it unwanted. “Colliding two protons is like colliding two oranges,” Dr Lyn Evans, director of the LHC project, said. “You’ll occasionally get a collision between two pips, the interesting bits, but you’ll get a lot of pulp. We need to reject an enormous amount of data to pick out the important bits.” Professor Virdee said that the data generated in one second was the equivalent of what all the world’s telecommunications generated in one year.
Even if this wealth of information proves the existence of the Higgs boson, the LHC will continue to serve scientific knowledge for decades.
“Let’s say we have the Higgs,” Dr Cashmore said. “I’d feel warm and content for a few microseconds, then I’d be asking new questions. Why does it affect different particles in different ways? “It would be spectacularly good to find it — I’m not trying to knock it — but it will pose a whole new set of problems. If we are an inquisitive society, these are the things we ought to be doing."
Yes, when an oddly privileged few are permitted to poop in the punchbowl (including the supposed no-no of reposting their own deleted harassing posts), some people will leave the party of their own accord. I'll anticipate a counter-argument and say that allowing such conditions to continue is purely a management decision. Still, it bites really bad.
I'm not a physicist, but you do sound like a pretty reasonable scientist, to me, to use this phrase.
Good question.
Here we have to distinguish between real and virtual particles. Real Higgs bosons decay almost immediately, but the Higgs field is composed of virtual Higgs bosons. There are two reasons why virtual Higgs bosons don't decay in the sense that real ones do: 1) they don't exist long enough, and 2) there isn't enough energy available to create the decay products of a Higgs.
Virtual particles are hard to visualize. On the one hand, they aren't "really there", in the sense that there isn't enough energy available for them to exist, and they can't be manipulated like a real particle. On the other hand, they "really exist", in the sense that they do exhibit a subtle--or even a strong--influence on whatever physics is taking place.
The canonical visualization centers on the Heisenberg Uncertainty Principle. It states that the uncertainty in energy times the uncertainty in time is intrinsically greater than some tiny quantity. One implication is that you can "borrow" an arbitrary amount of energy from the vacuum, provided you "pay it back" in a brief enough time that the inequality is satisfied. The more energy you borrow, the faster you have to pay it back, but as long as the HUP is respected, you won't violate any conservation laws. Since, in physics, whatever is possible is compulsory, the vacuum is therefore a boiling sea of every possible type of particle popping briefly in and out of existence.
If "mechanistic" is cool, science used to be cooler before "Quantum" got added in front of "Mechanics."
No, I don't like adjectives connected with my name in discussions either. But after receiving incoming and firing warning shots, I also may release a fusillade.
How fast?
From the level of vulgarity, we might assume it is the editorial staff at Popular Science.
Well the point that I hope would be learned by now is that one should not assume "Aha! there's fundamental mass (matter)!" when all that is indicated is energy and process in a system.
I suppose that jumping the gun in that way would be called "Materialistc Fundamentalism" ....or is that "Fundamentalist Materialism?"
Isn't that what you'd call it?
BTW, the ancient Hebrews had a very interesting word for this kind of thing, which is translated into our word, "glory," It tends to be noticed as light, for example, but the root word is "weight." Maybe those folks knew something about QM... or something?
Until they hit something that is painted black.
No argument here. I'm still fuming that the mods let their (ALS and conservababeJen)crap go on for so long then just summarily pulled the thread out from under us.
I didn't know Right Wing Professor very well, but he sounded like a decent Conservative scientist. He will be missed.
In memory of Right Wing Professor. BTTT!!!!
Maybe because mathematics was invented by humans to be a notational representation of agreed-on human logic, and human logic is far from perfect.
Not at all. There doesn't have to be a Higgs particle; it's just that the data we have strongly suggest that it exists, and it is mathematically the simplest answer to a number of questions. If the Higgs boson does not exist, something very interesting and obvious happens at LHC energies. A gigantic resonance (known as a "techni-rho") appears at energies less than about 1 TeV, caused by a very strong interaction between the W-bosons. And if there is no Higgs and no techni-rho...
but even once found cannot be seen. Hmmm....
It depends what you mean by "seen". Z bosons cannot be "seen", but the fact that they decay in our detectors means that they can be sensed with the right goggles, and that they possess reality in exactly the same sense as rocks and trees. I can't see songs, either; is my belief that they exist a matter of faith?
(OK, now you try composing a sentence with "stuff stuff is is.")
How heavy?
'... but just what the "stuff" stuff is is a puzzle.'
Would help if my own sentence was grammatical.
"Stuff, stuff,
'Is' is,
Oh, what a relief it is!"
(Picture Bill Clinton singing this while boinking an intern...)
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