CERN - Large Hadron Collider Experiment

Gimpy

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http://www.physorg.com/printnews.php?newsid=88786651


Physicists Develop Test for 'String Theory'

For decades, scientists have taken issue with "string theory" - a theory of the universe which contends that the fundamental forces and matter of nature can be reduced to tiny one-dimensional filaments called strings—because it does not make predictions that can be tested.

But researchers at the University of California, San Diego, Carnegie Mellon University, and The University of Texas at Austin have now developed an important test for this controversial "theory of everything."

Described in a paper that will appear in the January 26 issue of the journal Physical Review Letters, their test involves measurements of how elusive high-energy particles scatter during particle collisions. Most physicists believe those collisions will be observable at the Large Hadron Collider, or LHC, a subatomic particle collider scheduled to be operating later this year at the European Laboratory for Particle Physics, or CERN.

"Our work shows that, in principle, string theory can be tested in a non-trivial way," explained Ira Rothstein, co-author of the paper and professor of physics at Carnegie Mellon.

Rothstein and colleagues Jacques Distler, a professor of physics at The University of Texas at Austin; Benjamin Grinstein, a professor of physics at the University of California, San Diego; and Carnegie Mellon graduate student Rafael Porto developed their test based on studies of how strongly force-carrying particles called W bosons scatter in high-energy particle collisions generated within a particle accelerator. W bosons are special because they carry a property called the weak force, which provides a fundamental way for particles to interact with one another.

When the LHC turns on later this year, scientists will begin to investigate the scattering of W bosons, which has not been possible with other particle accelerators. Because the new test follows from a measurement of W boson scattering, it could eventually be performed at the LHC, according to the authors.

"The beauty of our test is the simplicity of its assumptions," explained Grinstein of UCSD. "The canonical forms of string theory include three mathematical assumptions—Lorentz invariance (the laws of physics are the same for all uniformly moving observers), analyticity (a smoothness criteria for the scattering of high-energy particles after a collision) and unitarity (all probabilities always add up to one). Our test sets bounds on these assumptions."

He added, "If the test does not find what the theory predicts about W boson scattering, it would be evidence that one of string theory's key mathematical assumptions is violated. In other words, string theory—as articulated in its current form—would be proven impossible."

"If the bounds are satisfied, we would still not know that string theory is correct," said Distler. "But, if the bounds are violated, we would know that string theory, as it is currently understood, could not be correct. At the very least, the theory would have to be reshaped in a highly nontrivial way."

String theory attempts to unify nature's four fundamental forces (gravity, electromagnetism, and the strong and weak forces) by positing that everything at the most basic level consists of strands of energy that vibrate at various rates and in multiple, undiscovered dimensions. These "strings" produce all known forces and particles in the universe, thus reconciling Einstein's theory of general relativity (the large) with quantum mechanics (the small).

Proponents say that string theory is elegant and beautiful. Dissenters argue that it does not make predictions that be tested experimentally, so the theory cannot be proven or falsified. And no particle accelerator yet exists that can attain the high energies needed to detect strings. Because of this technical limitation, tests of string theory have remained elusive until now.

"Since we don't have a complete understanding of string theory, it's impossible to rule out all possible models that are based on strings," said Rothstein. "However, most string theory models are based upon certain mathematical assumptions, and what we've shown is that such string theories have some definite predictions that can be tested."

Source: University of California, San Diego, By Amy Pavlak and Kim McDonald


This news is brought to you by PhysOrg.com

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Apologies if the article is too long. smile I've not read a lot on physics. My hubby was interested in ark's opinion on this machine's proposed capabilites, and if he thinks it might work.


Gimpy
 

ark

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Gimpy said:
Most physicists believe those collisions will be observable at the Large Hadron Collider, or LHC,
Gimpy
It is enough to read this sentence to see clearly that the author writes nonsense. First, no referendum has been made in the physics community. Second, even if some experts agree then what about those experts that disagree and criticise the idea with equally strong or even stronger arguments? In reading journal articles about scientific "brakthroughs" is is importnat to see the lobbies and journalistic need for ANY sensation. Quite often it can be clearly seen in the text itself.
 

John G

The Living Force
ark said:
In reading journal articles about scientific "breakthroughs" is is important to see the lobbies and journalistic need for ANY sensation. Quite often it can be clearly seen in the text itself.
and funny you should mention Peter Woit in the other thread cause this is most likely related to Jacques Distler's continuing temper tantrum with Woit; and having my alma mater involved (Carnegie Mellon) makes me glad my wife had me stop donating to them when we got married.

http://www.math.columbia.edu/~woit/wordpress/?p=510

Apparently even if what they want to see gets seen it will be because of ideas that exist quite happily outside the context of string theory. Someone joked that "does this mean that now any test of general relativity is now also going to be a test of string theory?".
 

aurora

Jedi Master
20:18 13 February 2007
NewScientist.com news service
Stephen Battersby

If we ever make black holes on Earth, they might be much stranger objects than the star-swallowing monsters known to exist in space. According to a new theory, any black hole that pops out of the Large Hadron Collider under construction in Switzerland might be surrounded by a black ring – forming a microscopic "black Saturn".
A black hole and a black ring can co-exist, in theory, as long as they are set spinning, say Henriette Elvang of MIT in Cambridge, US, and Pau Figueras of the University of Barcelona in Spain. "If you just had a ring, it would collapse. It's essential that it rotates to keep balanced," Elvang told New Scientist.
Just like the central black hole, the ring would be defined by its event horizon, a boundary beyond which nothing can escape the object's gravity. The ring could be thin like a rubber band or fat like a doughnut, and the rotation would flatten it – "like a doughnut that you have squashed," says Elvang. The spinning ring would also drag space-time around with it, making the central black hole spin as well.
The black Saturn can only exist in a space with four dimensions, rather than the three we inhabit. In 3D, a black ring is impossible, so there are no big black saturns out there for astronomers to spot – but at a microscopic level, they might really exist.
Ring sizesSome attempts to unify the forces of nature, notably string theory, involve extra dimensions of space. The extra dimensions are usually thought to be curled up tight, so small as to be inaccessible, but in some theories they can be big enough – maybe a fraction of a millimetre in size, maybe infinite – to probe with high-energy experiments. They remain hidden from our eyes because although gravity can reach out into these dimensions, all other forces are confined to our 3D world.
One consequence of these theories is that at short range, gravity becomes very strong. That means that a relatively small amount of stuff would be needed to make a microscopic black hole.
A few thousand times the mass-energy of a proton would be enough – producing a black hole no more than about 10-19 metres across.
If an extra dimension exists, black Saturns might be produced in the Large Hadron Collider (LHC) particle accelerator in Geneva, due to open at the end of 2007. Because there are so many ways to make a black Saturn, with different sizes of ring and different spins, they might even be produced in greater numbers than 'ordinary' black holes.
Fleeting appearanceIf so, the detectors at the LHC will light up. Physicist Stephen Hawking worked out in the 1970s that black holes evaporate, shedding their gravitational energy as so-called Hawking radiation.
Smaller ones evaporate faster, and any made in the LHC would last a tiny fraction of a split-second, producing a burst of all kinds of subatomic particles. Elvang's hole-and-ring combinations would do the same, but probably with a distinctive pattern. So the theory could be put to the test.
Of course there are a lot of "ifs" attached. The probability of large extra dimensions is still considered slim, and it is not clear whether a black Saturn would actually stabilise before evaporating.
But there is an outside chance that in a few years in a tunnel near Geneva, physicists will make a black hole far smaller than a proton and circled by a squashed four-dimensional black doughnut.
 

Iconoclast

Jedi Master
recently i watched a BBC documentary about the Large Hadron Collider at CERN.

they said there was a possiblility that it could create a mini black hole when it is switched on in november '07/early '08.

given the fact that conventional science works from the faulty/incomplete 'standard model theory', i wonder if there could be dramatic and unintended consequences from running the LHC.

on the other hand, the PTB surely didn't spend about 2 billion euros on something that doesn't (also) serve an ulterior motive.

hmmm...

i'm wondering if the C's have been asked about the consequences of switching that thing on?
 

Pierre

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From what the Cs said, creating a black hole looks like a real major achievement for a STS civilization.

session 941690 said:
A: STO flows outward and touches all including point of origin, STS flows inward and touches only origin point.
Q: (T) Well, they refer in the material that I am reading through, that they are STS through STO. (L) They serve self
BY serving others. (T) Is that what they mean? (L) Yeah. (T) Is that what we're supposed to do, serve ourselves by serving
others? (T) Yeah! Because what goes around, comes around. If you serve others then you get things back. (F) Because
when you serve yourself, all there is is an infinite number of individuals serving self. (T) There is no energy exchange, no
synergy within the group; there is no exchange. (F) Everything moves inward. (T) There is no sharing, no growth, there is no
nothing. (F) No interconnecting. (T) Right! There is no learning. (L) In terms of major STS, this may or may not be
related, could you tell us the nature of a Black Hole?
A: Grand Scale STS.
Q: (L) Is it like a being that has achieved such a level of STS
that it has literally imploded in on itself in some way?
A: Close analogy.
 

Mikey

The Living Force
A little internet search yielded (emphasis, mine):
http://en.wikipedia.org/wiki/Large_Hadron_Collider said:
As with the Relativistic Heavy Ion Collider (RHIC), people both inside and outside of the physics community have voiced concern that the LHC might trigger one of several theoretical disasters capable of destroying the Earth or even our entire Universe. [...] CERN performed a study to investigate whether such dangerous events as micro black holes, strangelets, or magnetic monopoles could occur. The report concluded, "We find no basis for any conceivable threat." If black holes are produced, they are expected to evaporate almost immediately via Hawking radiation and thus be harmless, although the existence of Hawking radiation is currently unconfirmed. Perhaps the strongest argument for the safety of colliders such as the LHC comes from the simple fact that cosmic rays of much higher energies than the LHC can produce have been bombarding the Earth, Moon and other objects in the solar system for thousands of millions of years with no such effects.
And here I found a short introduction of how the production and the decay of Micro Black Holes "work" (emphasis, mine):
http://backreaction.blogspot.com/2006/09/micro-black-holes.html said:
Inserting the expected technical details for the [LHC] collider, one finds a number of approximately 10^9 created black holes per year! This means, about one black hole per second. [...]

It was shown by Hawking in '75 that a black hole emits particles with a temperature that is inverse to its mass. This means, the smaller the black hole, the hotter it will be. Since we are talking about really tiny black holes, they are very hot. The typical temperature of the micro black holes is about 200 GeV or 10^16 Kelvin!

The evaporation rate (massloss per time) of the higher dimensional black hole can be computed using the thermodynamics of black holes. [...]

[In the course of the decay,] once the black hole has reached a mass close to the Planck mass, it falls into the regime of quantum gravity and predictions become increasingly difficult. It is generally assumed that the black hole will either completely decay in some last few Standard Model particles or a stable remnant will be left, which carries away the remaining energy. [...]

The high temperature results in a very short lifetime such that the black hole will decay close by the collision region and can be interpreted as a metastable intermediate state. [...]
So the fact that cosmic rays have much higher energies than the LHC can produce, lets me sleep well at night without fear of a black hole falling into the core of earth and sucking me in :)
 

Rabelais

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FOTCM Member
Hmmm... Ark?

Surfer dude stuns physicists with theory of everything

By Roger Highfield, Science Editor
Last Updated: 6:01pm GMT 14/11/2007



An impoverished surfer has drawn up a new theory of the universe, seen by some as the Holy Grail of physics, which as received rave reviews from scientists.

Garrett Lisi, 39, has a doctorate but no university affiliation and spends most of the year surfing in Hawaii, where he has also been a hiking guide and bridge builder (when he slept in a jungle yurt).

In winter, he heads to the mountains near Lake Tahoe, Nevada, where he snowboards. "Being poor sucks," Lisi says. "It's hard to figure out the secrets of the universe when you're trying to figure out where you and your girlfriend are going to sleep next month."

Despite this unusual career path, his proposal is remarkable because, by the arcane standards of particle physics, it does not require highly complex mathematics.

Even better, it does not require more than one dimension of time and three of space, when some rival theories need ten or even more spatial dimensions and other bizarre concepts. And it may even be possible to test his theory, which predicts a host of new particles, perhaps even using the new Large Hadron Collider atom smasher that will go into action near Geneva next year.


Although the work of 39 year old Garrett Lisi still has a way to go to convince the establishment, let alone match the achievements of Albert Einstein, the two do have one thing in common: Einstein also began his great adventure in theoretical physics while outside the mainstream scientific establishment, working as a patent officer, though failed to achieve the Holy Grail, an overarching explanation to unite all the particles and forces of the cosmos.

Now Lisi, currently in Nevada, has come up with a proposal to do this. Lee Smolin at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, describes Lisi's work as "fabulous". "It is one of the most compelling unification models I've seen in many, many years," he says.

"Although he cultivates a bit of a surfer-guy image its clear he has put enormous effort and time into working the complexities of this structure out over several years," Prof Smolin tells The Telegraph.

"Some incredibly beautiful stuff falls out of Lisi's theory," adds David Ritz Finkelstein at the Georgia Institute of Technology, Atlanta. "This must be more than coincidence and he really is touching on something profound."

The new theory reported today in New Scientist has been laid out in an online paper entitled "An Exceptionally Simple Theory of Everything" by Lisi, who completed his doctorate in theoretical physics in 1999 at the University of California, San Diego.

He has high hopes that his new theory could provide what he says is a "radical new explanation" for the three decade old Standard Model, which weaves together three of the four fundamental forces of nature: the electromagnetic force; the strong force, which binds quarks together in atomic nuclei; and the weak force, which controls radioactive decay.

The reason for the excitement is that Lisi's model also takes account of gravity, a force that has only successfully been included by a rival and highly fashionable idea called string theory, one that proposes particles are made up of minute strings, which is highly complex and elegant but has lacked predictions by which to do experiments to see if it works.

But some are taking a cooler view. Prof Marcus du Sautoy, of Oxford University and author of Finding Moonshine, told the Telegraph: "The proposal in this paper looks a long shot and there seem to be a lot things still to fill in."

And a colleague Eric Weinstein in America added: "Lisi seems like a hell of a guy. I'd love to meet him. But my friend Lee Smolin is betting on a very very long shot."

Lisi's inspiration lies in the most elegant and intricate shape known to mathematics, called E8 - a complex, eight-dimensional mathematical pattern with 248 points first found in 1887, but only fully understood by mathematicians this year after workings, that, if written out in tiny print, would cover an area the size of Manhattan.

E8 encapsulates the symmetries of a geometric object that is 57-dimensional and is itself is 248-dimensional. Lisi says "I think our universe is this beautiful shape."

What makes E8 so exciting is that Nature also seems to have embedded it at the heart of many bits of physics. One interpretation of why we have such a quirky list of fundamental particles is because they all result from different facets of the strange symmetries of E8.

Lisi's breakthrough came when he noticed that some of the equations describing E8's structure matched his own. "My brain exploded with the implications and the beauty of the thing," he tells New Scientist. "I thought: 'Holy crap, that's it!'"

What Lisi had realised was that he could find a way to place the various elementary particles and forces on E8's 248 points. What remained was 20 gaps which he filled with notional particles, for example those that some physicists predict to be associated with gravity.

Physicists have long puzzled over why elementary particles appear to belong to families, but this arises naturally from the geometry of E8, he says. So far, all the interactions predicted by the complex geometrical relationships inside E8 match with observations in the real world. "How cool is that?" he says.

The crucial test of Lisi's work will come only when he has made testable predictions. Lisi is now calculating the masses that the 20 new particles should have, in the hope that they may be spotted when the Large Hadron Collider starts up.

"The theory is very young, and still in development," he told the Telegraph. "Right now, I'd assign a low (but not tiny) likelyhood to this prediction.

"For comparison, I think the chances are higher that LHC will see some of these particles than it is that the LHC will see superparticles, extra dimensions, or micro black holes as predicted by string theory. I hope to get more (and different) predictions, with more confidence, out of this E8 Theory over the next year, before the LHC comes online."

http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/11/14/scisurf114.xml&CMP=ILC-mostviewedbox
 

John G

The Living Force
Someone might want to move this over to Outer and Inner Space discsussion. It's similar to Tony Smith's model, Tony got thanked by Garrett in the paper. Georgia Tech's David Finkelstein who gave a positive comment about Garrett's model was Tony Smith's advisor when Tony was a grad student at Georgia Tech. There are some differences, Garrett seems to stick to 4 dimensions for spacetime though to me he really seems to have more cause he goes up to SO(5) deSitter gravity and gets the Standard Model forces in a way that looks like how Tony does it (and Tony is using extra spacetime dimensions). Garrett does not go up to SO(6) conformal gravity like Tony does. Tony uses conformal gravity for the Higgs mechanism while Garrett has some complicated Higgs mechanism I don't understand even a little bit (too different from Tony). Garrett has all 3 generations of matter/antimatter as fundamental in the E8 model while for Tony the extra two generations are composite particles (though still described using E8). Garett has some not yet seen new particles and Tony just has the standard known particles. Both Garrett and Tony use a BRST quantization but Garrett is relying on future advances in Loop Quantum Gravity to really have a good picture (hence the relationship with Lee Smolin) while Tony already has his picture within the single E8 (ironically related to some work Lee Smolin had done on string theory even though Smolin is mostly a Loop Quantum Gravity researcher). Garrett and Tony have done some postings about this on physics blogs:

http://backreaction.blogspot.com/2007/11/theoretically-simple-exception-of.html
http://www.math.columbia.edu/~woit/wordpress/?p=617
 

ark

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After looking through the paper I had the following image: suppose you are to put the Rubik cube in the right order. You proceed and you "almost got it". Yet this is not the way, to really get it you need to go back to your original point and start with another move at the very start.

There are few nice things there - that are generally expected to have its place: E8 (related to octonions) and Clifford bundles (Waldyr Rodrigues used them extensively in his recent monograph(.

I wish Garrett well, yet I have an impression that sooner or later someone will find a serious flaw in his model.

Certainly it is not the solution to the main problem of physics, which is to understand the quantum theory.
 

John G

The Living Force
After reading Ark's SOTT Focus article, I thought I'd add an update for this. Garrett started a discussion for his paper here:

http://www.physicsforums.com/showthread.php?t=202439

For an unmoderated discussion (edit: oops it is a moderated forum), it is actually quite good. The discussion turned to some very Ark-like ideas... Clifford Algebra, Dirac Gammas, Conformal Gravity, Kaluza-Klein. There's a couple people who make one cringe by mentioning ideas like adding a 2nd E8 for supersymmetry or fitting in supergravity by using three monster groups (yikes) but even one of those two people had some good looking ideas too (and the other guy just showed up so he might have some less cringing thoughts too).
 
_http://www.misunderstooduniverse.com/France_Builds_Doomsday_Machine.htm


The Misunderstood Universe said:
Surprisingly, the United States of America, through the National Science Foundation and the Department of Energy, will be funding over $1 Billion Dollars towards this French experiment into creating potentially devastating black holes.
The obvious question that comes to mind is...why, why is this happening now of all times? The SOTT article by Arkadiusz Jadczyk relating to the possible time travel implications of this experiment was interesting yet I wonder if the intentions of this are simply benign research...I have the sneaking suspicion that whatever this device is being used for is not in the interest of humanity at all.
 
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