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."
That's literally how I envision it. At every point in space, there is an infinite number of things going on.
But, infinities are paradoxical, something along the lines of --- an infinite number of non-zero weight particles would weigh an infinite amount. That implies to me a minimum division of time and a maximum weight particle.
If this research were being done in the United States rather than Europe, someone here at FR would be complaining about how pure science isn't a express Federal power, and "how dare they put guns to my head and steal money from me for these 'scientists' to play their heretical Satanic games" etc. ad nauseaum.
Since it's a European facility, though, they'll probably just complain about the Satanic stuff.
That's the point that perplexed physicists for 15 years. The quantities calculated from Dirac's field theory were infinite. Furthermore, there were other infinities. For instance, real (not virtual) photons exhibit the behavior that, as you look at the number of photons being radiated by an accelerating electron, for example, the number of photons goes to infinity as you look at lower and lower frequencies. That should be no problem, as long as the sum of the photon energies is finite...but when you do the calculation, it isn't!
Then, in the late 1940's, three men independently noticed that if you perform all of the calculations properly and put everything together, the infinite sum of the virtual corrections--all those infinite electron-positron pairs, plus the virtual photons of the field)--almost exactly cancels the infinite sum of all the real photons. What's left is a residual quantity that agrees with the experimental results to more than 10 decimal places.
Feynman, Schwinger and Tomonaga received the 1965 Nobel Prize for this discovery (the "renormalization" of quantum electrodynamics). All of the quantum field theories of particle physics exploit the renormalization principle; for a theory to be considered calculable, it must be renormalizable.
[Geek alert: Gravity is a spin-2 field, meaning that each momentum-carrying quantum of the field (i.e. a graviton) carries two h-bar units of angular momentum. The problem that has plagued quantum theories of gravitation is that the theories are not renormalizable. It turns out that there are only two spaces in which a spin-2 field can be renormalized: one of them has 26 dimensions; the other has 11.]
That's what I thought, until around reply #83.
"evolution <== (( mantras )) tautology - Reason -- KNOWLEDGE // philosphy -- technology // science ==> creation ! "
You just went so far over my head that I didn't even feel the "whoosh" in my hair.
Yeah, but NORAD is going bonkers...
Under, not over.
So let me get this straight, any virtual particle pair can be expressed as an electron-positron pair plus photon pairs?
It seems to me that there is really no "longest" (time or whatever) and no "briefest". There is only "longer" and "briefer" - no limit. That is the nature of infinity which I believe is the nature of existence.
All the scientific discovery and application now occuring is the result of an evolutionary process of progress. The more physical knowledge we obtain, the more we can develop an understanding of spiritual causation. Nothing happens without some sort of energy cause and the ultimate energy Source is the infinite spiritual consciousness which human beings call the Creator.
Or maybe there is just a big guy in the sky making decisions about human activities (which makes no sense). Or maybe there is no cause or source and somehow intelligent existence happened anyway (which also makes no sense). Or maybe everything we see as real is just an illusion/dream and at some point we will awake to reality, and in that case it doesn't have to make sense.
One of the more surreal things I've heard recently was Mickey Dolenz (yes, of The Monkees) on local Houston talk radio (950 AM KPRC) explaining why scientists wanted to build the Superconducting Supercollider...
He was in town to star as the bad guy in a Houston production of the rock-opera version of "Aida", and was hitting the talk radio circuit as PR. During the interview he mentioned that he hated the idea of being a "celebrity", which he defined as "someone famous for being famous", and he'd rather get jobs or invitations based on his actual abilities, like music, acting, or his interest in quantum physics. So later in the show someone asked him a physics question about what the SSC would have been for. He gave a great and coherent answer, but it was just bizarre to hear one of the Monkees expounding on theoretical physics. That's about the last thing I expected when I turned on the radio that day.
Er...no.
And to think that people say he monkeys around.
Then we must limit what is produced in the vacuum to the electron-positron pairs? Or has a similar calculation been done for all virtual particles? Or, more likely, am I completely lost on the virtual sea and accept the canceling out of everything as a matter of trust?
Watch it now. He was a hero of mine in "Circus boy".(not kidding either-- about the hero anyway)
That's still what they're doing. All this test will determine is which theories *don't* match their differing predictions about what this test might find. Whatever the test results, it will reject some theories (maybe all current theories, if something really unexpected is observed).
Today, that is no longer a concern. A single test proves a theory (not a hypothesis) and new dimensions and particles are created to explain any contradictions!
Hardly. First, contrary to misleading language in this press article, no single test will "prove" any theory (although it can greatly *support* one and further firm up the likelihood of its being correct), because science doesn't deal in "proofs" of that sort. The reason is that there's always the possibility of some future observation which requires a further unexpected tweak (or rarely, a fundamental rewrite).
Second, particles aren't "created to explain contradictions". That's not how theoretical physics works. Instead, fundamental mathematical models is made which seems to explain current physical laws, and then the necessary consequences of those models are examined to see what else they predict (e.g., which other particles of what particular type must necessarily exist if the model is true, etc.). And then they perform experiments to see whether those necessary predictions hold water or not.
In the case of the "Standard Model", the mathematical consequences of that model imply that a certain type of particle, dubbed the "Higgs boson", would have to exist -- not in order to "explain contradictions", but because that (among other things) is what the mathematical model itself implies must exist if the model is true.
And if this "mathematically predicted" particle is detected after all and its properties match the predictions, then this is a very strong indication that the "Standard Model" is correct, or at least on the right track.
It's similar to how the position, motion, and mass of the planet Pluto was predicted before it was ever found, due to the mathematical implications of gravitational theory and the observed "wobbles" in the orbits of the known planets.
Yes, it was great. It richly deserved the Pulitzer it won.
Don't let the math (and there's really not a huge amount of it) get you down. You can "blurb" over it without having to personally follow or verify every step the author makes (although its' fun to do so if you can).
Much of the fun stuff in the book is philosophical (or other sorts of non-mathematical) anyway, and I can't think of any point that Hofstadter makes which is *only* supported mathematically. The math isn't the point of the book anyway, just enjoy the ride.
One warning: Sometimes a new chapter may appear to suddenly depart from what came before and start a totally new topic. Don't feel lost, it really *is* a new topic and you're not supposed to immediately see a connection to the prior chapter(s). What's fun, though, is that eventually the "new" material *is* suddenly tied back into the ongoing thread (or should I say "braid"?) of the book, and you discover that what appeared to be another topic entirely is yet another view of the same material.
The book is very intricately constructed, and at times I felt that if any paragraph had been lost, the whole thing would unravel like a tapestry with a broken thread. It's a truly remarkable work. Even if you can't follow any particular page, it's well worth going on so that you don't miss the several thousand other little joys to be found. The book covers an amazing amount of philosophical gems, musical and artistic insights, and a grand tour of some of the more interesting highlights of information theory, formal logic, epistemology, and a dozen other fields that most people never even dip a toe into.
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