New particle accelerator could rule out string theory

• 22:04 01 February 2007
• NewScientist.com news service
• David Shiga

String theory could be ruled out by experiments at the Large Hadron Collider (LHC), a particle accelerator scheduled to open by the end of 2007, a new study says. The finding offers a new approach for testing this potential "theory of everything", a goal that has so far proven elusive.

reposted from: New Scientist
my highlights / emphasis / edits

According to string theory, particles like electrons and photons are actually tiny, vibrating strings. The beauty of the theory is that it accounts for all of the known forces – including gravity, which the standard model of physics does not. But its critics have complained that there is essentially no way to test it.

Strong evidence for string theory could come from the observation of short-lived, mini black holes at the LHC (see Watching God play dice: The Large Hadron Collider). But the chance of them appearing is extremely small, so a failure to see them would not be a death blow for the theory.

In 2006, string theorist Allan Adams of MIT in Cambridge, US, and others offered a more promising check. They showed that some particle collisions could reveal whether certain fundamental assumptions underlying string theory are wrong.

Now, another team has shown that the energies needed to reveal such effects are achievable at the LHC, which is being built in Geneva, Switzerland. The team was led by Jacques Distler of the University of Texas in Austin, US.

High energies

One of string theory's assumptions comes from Einstein's theory of relativity – that the speed of light is the same for all observers, a principle called Lorentz invariance.

This principle – and three others underlying string theory – determine how strongly particles called W bosons, which transmit the weak nuclear force, interact.

If these interactions are below the strength calculated by Distler's team, it would signal that one of the assumptions built into string theory is incorrect and that therefore string theory itself is wrong, the researchers say.

"They did a very important thing," Adams told New Scientist.

Quantised space

If string theory does seem to be ruled out, physicists will have to find another theory of everything that can explain the LHC observations. "If we see these violations, people will start working very feverishly on some sort of alternative that will produce these violations," Distler told New Scientist.

That alternative may turn out to be a theory called loop quantum gravity, which posits that space itself is quantised into tiny chunks. Some physicists argue that loop quantum gravity does not satisfy Lorentz invariance. "So that's one possible direction people might go," Distler says.

Although the test could in principle rule out string theory if violations are found, both Distler and Adams suspect that the results will turn out to respect the four assumptions, leaving string theory as a viable candidate for the theory of everything.

Quantum World - Learn more about a weird world in our comprehensive special report.

Journal reference: Physical Review Letters (in press)

Large Hadron Collider - the basics

The Large Hadron Collider: Bring it on!

• 27 January 2007
• Davide Castelvecchi

reposted from: New Scientist
my highlights / edits

IT'S official: 2007 is the year of the LHC. In case you haven't heard, the initials stand for the Large Hadron Collider, which is nearing completion at the CERN laboratory near Geneva, Switzerland. Just a snowball's throw from Mont Blanc, it is not only the hottest thing in physics but also the largest, most elaborate scientific instrument of all time.

After 20 years of anticipation, the LHC is set to switch on this November, and soon thereafter CERN, the European Organization for Nuclear Research, will become the proud operator of the world's most powerful particle accelerator. It will smash protons together with seven times the energy and at 100 times the rate of the top collider to date, the Tevatron at Fermilab near Chicago. That will allow it to probe the interactions of particles down to the unprecedented scale of 10^-17 centimetres, roughly the size of the universe a trillionth of a second after the big bang, when the known fundamental forces of nature were born. The LHC is widely expected to usher in a new era of particle physics, perhaps even pointing the way to the fabled "theory of everything".

Not surprisingly, what lies ahead is making physicists positively giddy. "We are like children waiting for Christmas," says JoAnne Hewett, a theorist at the Stanford Linear Accelerator Center in Menlo Park, California. "You can't imagine the excitement." Immense technical hurdles remain, however, not least the problem of handling the amount of raw data the LHC will produce over its projected 20-year lifetime, which could exceed that in all the words spoken in human history.

Help might be on the way in the form of a controversial method for automating the data analysis. Some researchers, including Bruce Knuteson of Fermilab and the Massachusetts Institute of Technology, say their software is the fastest way to reveal hints of new physics. Others see it as a recipe for confusion and wild goose chases. The way future experiments are done and analysed may hinge on who is right.

The past dozen years have been a dry spell for particle physics. Despite all the theorists' fancy ideas, experimenters have found no new particles since 1995 when the top quark - the last in the family of six quarks which are among the building blocks of matter - was discovered at the Tevatron.

Since then, the immense multinational effort to build the LHC has gone into high gear, and the machine will start collecting data just over a year from now. Inside its 27-kilometre underground ring it will turn nanograms of hydrogen into two merry-go-rounds of protons travelling in opposite directions. Each beam will be loaded with 0.3 gigajoules of energy, equivalent to that of a 400-tonne French TGV train running at 140 kilometres per hour. The two beams of protons will crash head-on at several points in the ring where monumental detectors are now nearing completion. The largest of these, called Atlas (A Toroidal LHC ApparatuS) and CMS (Compact Muon Solenoid), are where thousands of researchers will be looking for new physics.

How exactly? Inside the detectors, the quantum shrapnel produced by colliding protons will scatter like colours in a Jackson Pollock painting. Courtesy of Einstein's E = mc², much of the protons' energy will mutate into mass, and the particles that come out as debris will often be heavier - even hundreds of times heavier - than the protons that went in. The researchers hope that among those heavy particles will be ones of a kind nobody has seen before. "The most exciting thing the LHC can potentially discover is something we cannot predict," says CERN theorist Alvaro De Rujula.

The LHC could produce particles that turn into ephemeral, mini black holes; particles that solve the mystery of dark matter; particles that spend much of their lives in other dimensions of space; or even particles that explain why the universe seems perfectly tuned for us to exist. No one will catch them directly, though. Rare particles tend to have very short lives and almost instantly decay into more ordinary stuff. So physicists must reconstruct the nature of the rare particles by looking at this debris.

At previous colliders, experimentalists usually knew how to do this. Virtually all the phenomena they observed fit the so-called "standard model" of particle physics developed in the 1970s, in which quarks, electrons, neutrinos, photons and other known particles play the fundamental roles. From its equations, physicists were able to calculate the patterns that should appear in the zillionth of a second after a collision. The main tool for this was invented by Richard Feynman in the 1950s: Feynman diagrams show how old particles can combine into new ones, annihilate into pure energy, procreate, and decay by splitting into other particles. Diagrams can include the cameo appearance of a hypothetical new particle, along with the signature combinations of outgoing stuff that betray its presence. Catch that signature in your detector and you can claim discovery of a particle even if you haven't observed it directly.

Hello Higgs

At the LHC, this time-honoured method should be useful for at least one task: finding the Higgs boson, the only particle in the standard model that has yet to be observed. The Higgs is the crucial link that explains how other particles such as quarks and electrons acquire their masses. Its discovery is expected to confirm the standard model as the ruler over all known forces except gravity. Despite the efforts of researchers at four machines, including ongoing measurements at the Tevatron, the Higgs has remained elusive.

All the predictions point to its mass being no more than 200 times the mass of a proton, which is well within the LHC's reach. If the LHC doesn't find it, that would mean that either Einstein's E = mc² or quantum theory - the two pillars of modern physics on which the standard model is predicated - is wrong. That would lead to a far greater upheaval in physics than the discovery of any new particle, but it's very unlikely. "The Higgs has to be there," says Fermilab theorist Joe Lykken.

So far so good, but the LHC's discoveries are expected to go beyond the standard model and include a zoo of new particles. Theorists have proposed hundreds of models for what such particles would look like, but they are all speculative. The LHC could validate one of these models, or perhaps show that they are all wrong. What is challenging is that some of the most popular models predict very similar signatures, which could give researchers fits when they try to figure out which is correct.

Take supersymmetry, which unites the various forces of nature at high energies. This model says that for each standard-model particle there exists a heavier "superpartner" particle. At the LHC, such superpartners should appear in pairs of identical, electrically charged particles. Seeing such pairs, or the particles they decay into, would be a sure sign of new physics, says Gordon Kane of the University of Michigan, Ann Arbor.

Trouble is, a similar signature is also predicted by a model called universal extra dimensions, in which each particle we see has more massive counterparts shadowing it in an additional dimension of space that we cannot see. Like superpartners, these would show up by decaying into pairs of identical particles with a net electric charge. The two types of counterparts would differ in a crucial quantum property known as spin, but the LHC does not have a direct way of measuring this.

For now, though, most experimentalists are less concerned about validating theories than they are about discovering new particles, a feat which would likely earn them a Nobel prize. "People always ask me, 'If you discover a new particle, how will you distinguish supersymmetry from extra dimensions?'" says Ian Hinchliffe, who leads one of the Atlas teams. "I'll discover it first, I'll think about it on the way to Stockholm, and I'll tell you on the way back."

That's all well and good, but a legitimate issue remains that could ultimately determine the success of the LHC. Waiting for specific patterns to hit the detectors - which is what most researchers plan to do, with each group specialising in just a few possible outputs - might mean missing the most interesting new physics.

Researchers at the Tevatron were able to discover the top quark because they knew it would tend to decay into one electron or muon (a heavier electron-like particle), one neutrino and hundreds of less interesting particles - and that's precisely what they found in the detectors. This "top-down" approach has worked fine at the energies probed so far, where virtually all observations have been in agreement with the standard model. On the rare occasion that unexplained phenomena have occurred, physicists have erred on the side of caution and put them down to statistical flukes, quantum fluctuations or measurement errors. That is expected to change at the energies produced by the LHC, where brand new phenomena should be plentiful. "The most likely scenario is that we're going to have a ton of weird stuff to explain," says Nima Arkani-Hamed, a theoretical physicist at Harvard University.

"The most likely scenario is that we're going to have a ton of weird stuff to explain"

That's why some researchers, including Arkani-Hamed, say a revised approach is called for. Instead of trying to check whether a particular model can fit a predetermined signature, they would examine all patterns of debris hitting the detectors that can't be explained by the standard model, and which are frequent enough to not be statistical flukes. They would then work upwards from these observations to make a guess at which model is likely to fit the data. This process, says Arkani-Hamed, needs the participation of theorists who in the past have rarely taken part in analysing data. It would rely on sophisticated software to select which patterns of debris, or "channels", to look at.

Such software has recently been developed by Knuteson, Stephen Mrenna and others at Fermilab, and by Sascha Caron and collaborators at the DESY lab in Hamburg, Germany. Knuteson started working on these methods in the late 1990s, and when he has applied them to Tevatron data the results have matched the speed and accuracy of conventional top-down methods. That much is uncontroversial. Where Knuteson and Mrenna have broken contentious new ground is in creating an algorithm aimed at a more ambitious bottom-up search for new physics (www.arxiv.org/hep-ph/0602101).

Reverse Feynman

For a given channel - an unusual combination of quarks and neutrinos, say - the computer uses quantum theory to reverse-engineer the hundreds of possible Feynman diagrams that could have produced these particles, and suggests ways to tweak the standard model to explain them - perhaps by introducing a new particle at an intermediate stage. This might be a superpartner of a regular particle, or something else entirely. "It begins to automate the building of new models," says Knuteson.

Critics say that this could lead to too many false alarms. "When you look at such immense sets of data, there are always statistical fluctuations," warns Michelangelo Mangano of CERN. "This kind of approach has made people claim false discoveries, slowing down the progress of physics." Knuteson's team insists that the software has safeguards against this, and can discern which hints of new physics are statistically most relevant. One event in an unexpected channel would be dismissed, but hundreds of them - especially if the standard model says they should be rare - would flag up something worth paying attention to.

It is too early to know who is right, and what exactly the bottom-up approach will yield. Knuteson plans to join the CMS experiment, where he says that looking at hundreds of channels simultaneously should accelerate the process of discovery. Caron is already a member of Atlas, where he plans a similarly broad search. If their approach proves successful it could eventually change the way theoretical physics is done. "We will get to the point where developing new theories, something currently in the human domain, will be done by computers," Knuteson says.

However the results from the LHC are interpreted, hopes are high that they will lead us to new and unexpected discoveries about the most basic influences in the universe. That is where the excitement really begins, and Arkani-Hamed is confident that it will be people, not machines, that make the breakthroughs. "Going from the data to a beautiful theory," he says, "is something a computer will never do."

Davide Castelvecchi is a science writer based in Washington DC

From issue 2588 of New Scientist magazine, 27 January 2007, page 36-39

Will the Standard Model of physics be verified sooner?

reposted from: http://blog.wired.com/wiredscience/2007/01/the_god_particl.html

Tuesday, 9 January 2007

The God Particle Maybe Loses Some Weight
Topic: physics

Fascinating story today over at Nature's web site (here) on a new calculation for the mass of the W particle, the particle that carries the weak nuclear force—the one that does radioactive decay.

See, you're yawning. But author Jenny Hogan does a fantastic job of putting the W's lighter weight into context.

If the W is lighter, then so must be the much-sought-after Higgs boson, the theoretical particle that is responsible for mass—everything weighs something, and the Higgs is thought to explain why. It's so important that physicists have nicknamed it "the God particle."

And if the Higgs is lighter than physicists thought, then we might not have to wait for the Large Hadron Collider, a brand new, massive particle smasher, to come online at CERN, the European particle physics lab. The LHC is scheduled to start smacking stuff into each other this year. Instead, the folks who run the Tevatron, the big collider at Fermilab in Illinois, might be able to nab the Higgs first.

On 8 January, the estimate was tightened when the CDF [Collider Detector at Fermilab] announced it had pinned down the mass of the W boson, which mediates the weak nuclear force involved in processes such as radioactive decay. The new measurement is in agreement with previous estimates, but towards the upper end of the range. This, along with the added precision in the measurement, brings the upper limit for the Higgs' mass down to 153 giga electronvolts from 166 GeV. Previous experiments have shown that the Higgs must be heavier than 114 GeV.

A lighter Higgs suits the Tevatron, which is only capable of finding the particle if its mass is less than around 170 GeV. The closer a particle's mass is to this upper limit, the harder it would be to find.

Anything heavier than 170 GeV would certainly have to wait for the LHC, which will smash protons together harder to probe higher energies.

So I suppose you might ask, why would anyone believe the Fermilab guys on the new weight for the W when it clearly favors them in the race for the Higgs. And the answer is...um...physics? And the folks at Fermilab readily admit their desire to get there first. But author Hogan rightly points out that finding the Higgs is going to take years of data collection and analysis at both labs (see this Wired story if you want to know more about the LHC's number-crunching plans). She further points out that if the Standard Model of physics, the one that lists all the known and theoretical particles, is wrong, then there might not be a Higgs boson.

That, my friends, is context.

Higgs boson explains why other particles have mass

reposted from: http://news.bbc.co.uk/1/hi/sci/tech/6244899.stm
Experts home in on 'God particle'

Cern's Atlas detector will search for the elusive "God particle" (Image: Cern/Maximilien Brice) Enlarge Image

Scientists may be closing in on the most sought-after particle in physics.

The hypothetical Higgs boson, often dubbed the "God particle", is fundamental to our understanding of the Universe but has yet to be detected.

Now, data from the Tevatron particle collider at Fermilab, in the US, has enabled the most precise calculation yet to be made for its predicted mass.

And this, the international team says, narrows the window in which to locate the elusive particle.

Adding weight

The Higgs boson has been proffered to explain the mystery of why other particles have mass, and forms the missing piece in the puzzle that is the Standard Model - the current theory used to describe the fundamental nature of matter.

For years, researchers have been searching the sub-atomic "soup" created when particles are smashed together in colliders - but no sign of the Higgs has been seen.

In obtaining a more precise predicted mass for the Higgs, the particle's existence can be confirmed or ruled out within two to three years, scientists believe.

The calculation has been done by making the finest measurement to date of the mass of another elementary particle, one that is well known, the W boson.

After more than 10 years, we are now homing in on the Higgs Dr Mark Lancaster

The W boson is the carrier of weak nuclear force, one of the fundamental forces in nature, and its mass is believed to be linked to that of the Higgs'.

Using this new measurement, together with the calculated mass of another fundamental particle, the top quark, the Fermilab team has worked out a new predicted mass for the Higgs boson, discovering it might be lighter than previously thought.

Dr Mark Lancaster, UK spokesman for the Collider Detector at Fermilab (CDF), from University College London, said: "These findings narrow down the mass region that we expect the Higgs to appear in.

"After more than 10 years, we are now homing in on it."

And searching data within this region at Fermilab's Tevatron and Europe's Large Hadron Collider at Cern, which switches on next year, could reveal whether the Higgs boson is present or not by the middle of 2009, he added.

"And if we don't find it, it is going to be back to the drawing board for particle physics."

The Standard Model is a theory devised to explain how sub-atomic particles interact with each other There are 16 particles that make up this model (12 matter particles and 4 force carrier particles). But they would have no mass if considered alone The Higgs boson explains why these particles have mass. Particles acquire their mass through interactions with an all-pervading field, called the Higgs field, which is carried by the Higgs boson.

the nature of dark matter, dark energy, the cyclic universe, gravitational waves

Reposted from: http://edge.org/q2007/q07_15.html
my highlights in blue

PAUL STEINHARDT
Physicist; Albert Einstein Professor of Science, Princeton University; Coauthor, Endless Universe: A New History of the Cosmos

Bullish on Cosmology

I am optimistic that there will be a historic breakthrough in our understanding of the universe in the next five years that will be remembered as one of the most significant of the millennium. I would also give better-than-even odds that there will be more than one discovery of this magnitude.

My optimism is sparked by a remarkable coincidence: the simultaneous maturing of several unrelated technologies, each of which could open a new window on the cosmos. Historically, every new technology is a harbinger of great discovery. Consider, then, that at least a handful of major advances will occur within just five years:

• Directly detecting of dark matter:

After decades of gradual progress, physicists will finally build the first detectors sensitive enough to detect dark matter particles directly, if they consist of weakly interacting massive particles (WIMPs), as many physicists suspect.

• Discovering the nature of dark energy:

Although their names sound similar, the only quality dark matter and dark energy have in common is that they are both invisible. Dark matter consists of massive particles that gravitationally attract one another and clump into clouds that seed the formation of galaxies.

Dark energy is gravitationally self-repulsive, so it tends to smooth itself out. When it is the dominant form of energy, as it is today, dark energy causes the expansion of the universe to speed up.The composition of dark energy is one of the great mysteries of science, with profound implications for both fundamental physics and cosmology.

Over the next five years, arrays of novel wide-field telescopes will be constructed that are programmed to rapidly scan large fractions of the sky to search for astronomical phenomena that vary rapidly with time. The arrays will be used to search for distant supernovae (exploding stars), whose brightness and colors can be used to judge the distance and recessional speed of their host galaxies. From these measurements, astronomers can measure precisely the accelerated expansion of the universe, a primary means of distinguishing different theories of dark energy.

At the same time, in the laboratory, physicists will be trying to detect changes in the gravitational force when masses are placed at close proximity or tiny changes in the strength of the electromagnetic force with time, other effects predicted by some theories of dark energy. These measurements will significantly narrow the candidates for dark energy, perhaps identifying a unique possibility.

• Exploring the big bang and the origin of the large-scale structure of the universe:

The conventional wisdom is that the universe sprang into existence 14 billion years ago in a big bang and that a period of exponentially rapid inflationary expansion accounts for its large-scale structure. However, the last decade has seen the emergence of alternative possibilities, such as the cyclic model of the universe.

In the cyclic model, the big bang is not the beginning but, rather, an event that has been repeating every trillion years, extending far into the past. Borrowing ideas from string theory, the cyclic model proposes that each bang is a collision between our three-dimensional world and another three-dimensional world along an extra spatial dimension. Each bang creates new hot matter and radiation that begins a new period of expansion, cooling, galaxy formation and life, but space and time exist before and after the bang.

The large-scale structure of the universe and the pattern of galaxies are set by events that occurred about a cycle ago, before the bang, just as events occurring today are setting the structure for the cycle to come. Although the inflationary and cyclic pictures predict distributions of galaxies, matter and radiation that are indistinguishable, their predictions for the production of gravitational waves in the early universe are exponentially different.

Gravitational waves are ripples in space produced during inflation or near the beginning of a new cycle that propagate through the universe and distort space like undulations traveling through jello. These cosmic gravitational waves are too weak to be detected directly, but experimental cosmologists throughout the world are mounting ground- and balloon-based experiments to search for their imprint on the polarization pattern of cosmic microwave background radiation produced in the first 380,000 years after the bang.

The results will not only affect our view of our cosmic origin, but our future as well. The conventional big bang inflationary theory predicts our universe is headed towards the cold oblivion of eternal expansion—a whimper—but the cyclic model predicts a new hot big bang.

• Direct detecting gravitational waves:

The first window on the universe using something other than electromagnetic waves could be open within the next five years. After decades of developments, the LIGO (Laser Interferometer Gravitational Wave Observatory), with one detector in Livingston, Louisiana, and one in Hanford, Washington, has a plausible chance of directly detecting gravitational waves, beginning a new era in astronomy.

The observatory is designed to detect stlronger gravitational waves than those produced in the early universe, such as waves generated by the violent collision of neutron stars and black holes in our own galaxy. However, this frontier is so fresh and unexplored that there could well be unanticipated cosmic sources of strong gravitational waves to be discovered that could cause us to reassess our understanding of the universe.

• Breakthroughs in fundamental physics and direct production of dark matter:

The Large Hadron Collider at the Center for European Research (CERN) in Geneva, Switzerland, is set to begin operation this year. This facility consists of a powerful particle accelerator that will reproduce collisions of the type that occurred within the first pico-second after the big bang, carrying the investigation of fundamental physics over an important energy threshold where new phenomena are anticipated. For example, physicists hope to discover a spectrum of new "supersymmetric" particles, confirming a key prediction of string theory, and also WIMPs that may comprise the dark matter.

The impact will be profound. As we enter 2007, we understand the composition of less than five percent of the universe; we do not understand how space, time, matter and energy were created; and we cannot predict where the universe is headed. In the next five years, we may witness the historic resolution of one or more of these issues. I have my personal bet on what the individual outcomes will be; but the only prediction I will reveal here is that, with the opening of so many new windows on the cosmos, we are sure to discover something unanticipated and astonishing.

Physics Will Not Achieve a Theory of Everything

Reposted from: http://edge.org/q2007/q07_14.html
my highlights in blue

FRANK WILCZEK
Physicist, MIT; Recipient, 2004 Nobel Prize in Physics; Author, Fantastic Realities

Physics Will Not Achieve a Theory of Everything

I'm optimistic that physics will not achieve a Theory of Everything.

That might seem an odd thing to be optimistic about. Many of my colleagues in physics are inspired by the prospect of achieving a Theory of Everything. Some even claim that they've already got it. (Acknowledging, to be sure, that perhaps a few i's remain to be dotted or a few t's to be crossed.) My advice, dear colleagues: Be careful what you wish for. If you reflect for a moment on what the words actually mean, a Theory of Everything may not appear so attractive. It would imply that the world could no longer surprise us, and had no more to teach us.

I don't buy it. I'm optimistic that the world will continue to surprise us in fascinating and fundamental ways.

Simply writing down the laws or equations is a long way from being able to anticipate their consequences. Few physicists—and no sober ones—seriously expect future work in fundamental physics to exhaust, for example, neuroscience.

A less literal reading of "Theory of Everything" is closer to what physicists who use it mean by it. It's supposed to be a theory, not really of everything, but of "everything fundamental". And here "fundamental" is also being used in an unusual, technical sense. A more precise word here might be "basic" or "irreducible". That is, the physicists' Theory of Everything is supposed to provide all the laws that can't be derived logically, even in principle, from other laws. The structure of DNA surely emerges—in principle—from the equations of the standard model, and I strongly suspect that the possibility of Mind does too. So those phenomena, while they are vastly important and clearly fundamental in the usual sense, aren't fundamental in the technical sense, and elucidating them is not part of a Theory of Everything.

I think we're about to enter a new Golden Age in fundamental physics. The Large Hadron Collider (LHC), which should begin to operate at CERN, near Geneva, starting in summer 2007, will probe the behavior of matter at energies higher than ever accessed before. There is no consensus about what we'll find there. I'm still fond of a calculation that Savas Dimopoulos, Stuart Raby and I did in 1981. We found—speaking roughly—that we could unify the description of fundamental interactions (gauge unification) only within an expanded version of relativity, which includes transformations of spin (supersymmetry). To make that dual unification we had to bring in new particles, which were too heavy to be observed at the time, but ought to be coming into range at the LHC. If they do exist we'll have a new world of phenomena to discover and explore. The astronomical riddle of dark matter could well be found there. Several competing ideas are in play, as well. The point is that whatever happens, experimenters will be making fundamental discoveries that take us by surprise. That would be impossible, if we had a Theory of Everything in the sense just described—that is, of everything fundamental.

In recent months a different, much weaker notion of what a "Theory of Everything" might accomplish has gained ground, largely inspired by developments in string theory. In this concept, the Theory provides a unique set of equations, but those equations that have many solutions, which are realized in different parts of the Universe. One speaks instead of a multiverse, composed of many domains, each forming a universe in itself, each with its own distinctive laws. Now even the fundamental—i.e., basic, irreducible—laws are beyond the power of the Theory to supply, since they vary from universe to universe. At this point the contrast between the grandeur of the words "Theory of Everything" and the meager information delivered becomes grotesque.

The glamour of the quest for a Theory of Everything, or a Final Theory, harks back Einstein's long quest for his version, a Unified Field Theory. Lest we forget, that quest was fruitless. During his great creative period, Einstein produced marvelous theories of particular things: Brownian motion, the photoelectric effect, the electrodynamics of moving bodies, the equality of inertial and gravitational mass. I take inspiration from the early Einstein, the creative opportunist who consulted Nature, rather than the later "all-or-nothing" romantic who tried (and failed) to dictate to Her. I'm optimistic that She'll continue to surprise me, and my successors, for a long time.

The Return of the Discipline of Experiment Will Transform Our Knowledge of Fundamental Physics

Reposted from: http://edge.org/q2007/q07_8.html
my highlights in blue

LEE SMOLIN
Physicist, Perimeter Institute; Author, The Trouble With Physics

The Return of the Discipline of Experiment Will Transform Our Knowledge of Fundamental Physics

In science as in politics it seems that Eldredge and Gould's metaphor of punctuated equilibrium holds. When progress happens, it happens fast and the whole culture vibrates with the excitement of it. We have had a bit too much equilibrium lately, of disappointed expectations following as a natural consequence of unwisely reduced ambitions. But I am optimistic that the next decades will see breakthroughs in key problems on which we now seem stuck. In physics, new experiments including the LHC, AUGER, GLAST, PLANCK, LIGO and others are likely to transform our knowledge of fundamental physics, and end the long period when theory sought to progress without the discipline of experiment. Very likely we will be surprised and humbled by what is seen, but this will be followed by rapid progress as new ideas are quickly invented to explain the surprising data.

How can I be optimistic without knowing what direction science will take? This is exactly the point. There are two kinds of optimism, the optimism of people who think they know the future and the optimism of people who believe the future will be more interesting and, if always imperfect, more wonderful than they can imagine. I am of the second kind. The first kind sometimes comes along with a belief that time and change are illusions, and that the world is evolving towards an eternal timeless state of perfection. This is the optimism of religious fundamentalists and orthodox Marxists, and one sees it reflected also in the cosmologies in which our evolving universe is just a transient fluctuation in an otherwise permanent state of thermal equilibrium. The opposite kind of optimism lies behind the evolutionary theorists who believe the world is so intricate that the simplest mechanism that could predict the future of life and the cosmos is the universe itself. If we are the first kind of optimist we seek to transcend the complexities of life to discover something eternal behind it, something like the imagined view of God. If we are the second, we seek to live and think within the swirl of life; we aim for comprehension and wisdom but have no illusions of transcendence or control.

society will increasingly recognize and understand the value of knowledge. People will want to make their own critical judgments

Reposted from: http://edge.org/q2007/q07_6.html
my highlights in blue


LISA RANDALL
Physicist, Harvard University; Author, Warped Passages


People Will Increasingly Value Truth (Over Truthiness)

Optimism is an "ism" like any other. People reading these pages should recognize the responses as the hopeful beliefs that they are. With this caveat, I'm optimistic that people will increasingly value truth (over truthiness). After recent digressions into beliefs and images dominating current thought, I'm anticipating that society will increasingly recognize and understand the value of knowledge. People will want to make their own critical judgments, know more facts, and stop deferring to questionable authorities or visual media for their education. I don't necessarily think everyone will do so. But I'm optimistic that the ones who do won't remain a silent minority.

Part of my optimism stems from my experiences talking and writing about the future of particle physics to the public and the surge of interest I've found when people realize how much they can learn and understand. All of us in the particle physics community are eagerly awaiting the Large Hadron Collider (LHC), a proton-proton collider being built in Switzerland that will turn on in 2007 and begin its real operation in 2008. I'm optimistic (with calculations that support my optimism) that this machine will tell us about the nature of mass and explain to us the weakness of gravity relative to the other known elementary particle forces. I'm optimistic that we'll learn something truly new and exciting about the fundamental nature of matter and our world-maybe something as exciting as extra dimensions of space—or perhaps something no one has even thought about yet. Whatever the results will be, the LHC gives reason to be optimistic.

The Secret of Life, the Universe and Everything

reposted from Edge.org

LAWRENCE KRAUSS
Physicist, Case Western Reserve University; Author, Atom

Renewal of Science for the Public Good

I am optimistic that after almost 30 years of sensory deprivation in the field of particle physics, during which much hallucination (eg. string theory) has occurred by theorists, within 3 years, following the commissioning next year of the Large Hadron Collider in Geneva, we will finally obtain empirical data that will drive forward our understanding of the fundamental structure of nature, its forces, and of space and time.

My biggest optimism is that the data will be completely unexpected, forcing revisions in all our carefully prepared ideas about what will supplant the Standard Model of elementary particle physics. Since 1975 or so, every single experiment done at the microscopic forefront has been consistent with the predictions of the Standard Model, giving little or no direction to what lies behind it, what is the origin of mass, why there are three families of elementary particles, why some quarks are heavy, and why neutrinos are very light.

Yes, neutrino masses were discovered, but that was no big surprise, and no insight at all into their origin has been obtained thus far. With empirical data, theoretical particle physics might once return to the days when the key to distinguishing good theory from bad was how many empirical puzzles the theory might resolve, rather than how fancy it might look.

I am also completely optimistic that within what I hope will be my lifetime we will unlock the secret of life, and finally take our understanding of evolutionary biology back to that remarkable transition from non-biological chemistry to biology. Not only will we be able to create life in the laboratory, but we will be able to trace our own origins back, and gain insight into the remarkable question of how much life there is in the universe. We will surely discover microbial life elsewhere in our solar system, and I expect we will find that it is our cousin, from the same seed, if you will, rather than being truly alien. But all of this will make living even more fascinating.