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."
Bull! Causality means something. The fact that disconnection from causality has been invoked is by nature admitting a problem with inflation and relativity.
Peter Higgs, Professor (Emeritus) of theoretical physics at Edinburgh University
Age: 60
Educated: Cotham Grammar School, Bristol, and King's College London.
Claim to fame: Predicted the Higgs bosun particle in the Sixties,
Avast ye swabbies!
Fine. Go ahead and explain what you mean by a disconnection from causality as it relates to Relativity and Inflation.
I'm not the one invoking causality to explain away the problem. However, it is essentially saying you can attain or exceed the velocity of light as long as you can't "measure"(detect) it.
If you aren't invoking causality, who is?
Who or what is "it" in your second sentence?
Oh, indeed! What do you think it means?
The fact that disconnection from causality has been invoked is by nature admitting a problem with inflation and relativity.
Well, I don't know what "disconnection from causality" means, but are you trying to say that the math doesn't work out?
Here--->Inflation
This is a very remarkable behavior. It means that two points that are initially in causal contact (d < dH) will expand so rapidly that they will eventually be causally disconnected. Put another way, two points in space whose relative velocity due to expansion is less than the speed of light will eventually be flying apart from each other at greater than the speed of light! Note that there is absolutely no violation of the principles of relativity. Relative velocities v > c are allowed in general relativity as long as the observers are sufficiently separated in space.
That to me, means that things can go faster than light, you just can't "see" them.
Causality is defined in the link---> (d < dH). The distance between 2 points is less than the light horizon. It is obvious that the horizon expands at the speed of light. Therefore, if an object is at a distance less than that horizon(within the light cone of the other object) at any time it must travel faster than the horizon's velocity to be greater than the horizon(outside the light cone); that is, from this (d < dH) to this (d > dH).(it must do so while within the horizon--the superluminal velocity). Explicitly, if a distance grew(separated) 1 mm in 10-33 seconds, it would have to "travel" at least 1030 m/s during some portion of the growth. The speed of light is somewhat slower than that.
All of this using a given Universal Time Zone, a specified absolute T.(Hey, I'm not the one specifying T, it's the inflation guys and their timeline.)
Causality means that causes always precede effects. Do you understand why d < dH is equivalent?
It is obvious that the horizon expands at the speed of light.
As a matter of fact, during inflation the horizon shrinks.
Isn't that the problem?(things move outside the horizon)
I'm not mincing words, I'm stating exactly what happens. How does the horizon shrink? Does light change speed? Does light go backwards? A light cone has a definite shape. It is a cone, not a coke bottle.
The Hubble parameter--the temporal curvature of the universe--changes. As space stretches faster and faster, the distance over which the accumulated Hubble expansion exceeds the speed of light gets smaller and smaller. For example, if the Hubble constant suddenly became 300,000,000 s-1, then you couldn't see any objects farther away than one meter, by virtue of the fact that anything beyond that would have a speed greater than c relative to you. Any light that happened to be in transit from any more distant object at the time of the phase transition would be redshifted away to invisibility.
Imagine you're driving in a long line of cars. You can see cars that are a certain distance away. As you drive, you start to go around a gentle curve, and you lose sight of some of the most distant cars. The curve gets tighter, and you lose more cars still. Then, you go around a very tight curve, and you can only see one car ahead of you.
What happened? Did those other cars suddenly zoom away? Did you go backwards? Did it suddenly get foggy?
The analogy isn't quite perfect, because the car example is based on spatial curvature rather than on temporal curvature, but it conveys the correct idea that the temporary loss of contact is a geometrical thing.
Now, how again would this lead to effects preceding causes?
Well, inflation flattens rather than steepens curvature. And things still have to travel faster than light to not been seen "after" they have been seen.
Inflation flattens spatial curvature. Read again what I wrote.
And things still have to travel faster than light to not been seen "after" they have been seen.
That's perfectly acceptable. As long as it doesn't lead to effects preceding causes, it doesn't violate the principle of relativity.
I did read your post and we are speaking of space. Velocities happen in space. Now what determines time? Is it completely fictional? What is time at A and how does it relate to time at B?
"It" doesn't violate causality since we can't see "it" and you are fudging with "time", whatever that is, in the situation describing inflation.
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