Seven questions that keep physicists up at night

• 23:58 23 October 2009 by Ivan Semeniuk, Waterloo
• For similar stories, visit the Quantum World Topic Guide

It's not your average confession show: a panel of leading physicists spilling the beans about what keeps them tossing and turning in the wee hours.

That was the scene a few days ago in front of a packed auditorium at the Perimeter Institute, in Waterloo, Canada, when a panel of physicists was asked to respond to a single question: "What keeps you awake at night?"

The discussion was part of "Quantum to Cosmos", a 10-day physics extravaganza, which ends on Sunday.

While most panelists professed to sleep very soundly, here are seven key conundrums that emerged during the session, which can be viewed here.

Why this universe?

In their pursuit of nature's fundamental laws, physicists have essentially been working under a long standing paradigm: demonstrating why the universe must be as we see it. But if other laws can be thought of, why can't the universes they describe exist in some other place? "Maybe we'll find there's no other alternative to the universe we know," says Sean Carroll of Caltech. "But I suspect that's not right." Carroll finds it easy to imagine that nature allows for different kinds of universes with different laws. "So in our universe, the question becomes why these laws and not some other laws?"

What is everything made of?

It's now clear that ordinary matter – atoms, stars and galaxies – accounts for a paltry 4 per cent of the universe's total energy budget. It's the other 96 per cent that keeps University of Michigan physicist Katherine Freese engaged. Freese is excited that one part of the problem, the nature of dark matter, may be nearing resolution. She points to new data from experiments like NASA's Fermi satellite that are consistent with the notion that dark matter particles in our own galaxy are annihilating with one another at a measurable rate, which in turn could reveal their properties. But the discovery of dark energy, which appears to be speeding up the expansion of the universe, has created a vast new set of puzzles for which there are no immediate answers in sight. This includes the nature of the dark energy itself and the question of why it has a value that is so extraordinarily small, allowing for the formation of galaxies, stars and the emergence of life.

How does complexity happen?

From the unpredictable behaviour of financial markets to the rise of life from inert matter, Leo Kadananoff, physicist and applied mathematician at the University of Chicago, finds the most engaging questions deal with the rise of complex systems. Kadanoff worries that particle physicists and cosmologists are missing an important trick if they only focus on the very small and the very large. "We still don't know how ordinary window glass works and keeps it shape," says Kadanoff. "The investigation of familiar things is just as important in the search for understanding." Life itself, he says, will only be truly understood by decoding how simple constituents with simple interactions can lead to complex phenomena.

Will string theory ever be proved correct?

Cambridge physicist David Tong is passionate about the mathematical beauty of string theory – the idea that the fundamental particles we observe are not point-like dots, but rather tiny strings. But he admits it once brought him to a philosophical crisis when he realised he might live his entire life not knowing whether it actually constitutes a description of all reality. Even experiments such as the Large Hadron Collider and the Planck satellite, while well positioned to reveal new physics, are unlikely to say anything definitive about strings. Tong finds solace in knowing that the methods of string theory can be brought to bear on less fundamental problems, such as the behaviour of quarks and exotic metals. "It is a useful theory," he says, "so I'm trying to concentrate on that."

What is the singularity?

For cosmologist and Perimeter Institute director Neil Turok, the biggest mystery is the one that started it all, the big bang. Conventional theory points back to an infinitely hot and dense state at the beginning of the universe, where the known laws of physics break down. "We don't know how to describe it," says Turok. "How can anyone claim to have a theory of everything without that?" Turok is hopeful that string theory and a related development known as the "holographic principle", which shows that a singularity in three dimensions can be translated into a mathematically more manageable entity in two dimensions (which may imply that the third dimension and gravity itself are illusory). "These tools are giving us new ways of thinking about the problem, which are deeply satisfying in a mathematical sense," he says.

What is reality really?

The material world may, at some level, lie beyond comprehension, but Anton Zeilinger, professor of physics at the University of Vienna, is profoundly hopeful that physicists have merely scratched the surface of something much bigger. Zeilinger specialises in quantum experiments that demonstrate the apparent influence of observers in the shaping of reality. "Maybe the real breakthrough will come when we start to realise the connections between reality, knowledge and our actions," he says. The concept is mind-bending, but it is well established in practice. Zeilinger and others have shown that particles that are widely separated can somehow have quantum states that are linked, so that observing one affects the outcome of the other. No one has yet fathomed how the universe seems to know when it is being watched.

How far can physics take us?

Perhaps the biggest question of all is whether the process of inquiry that has revealed so much about the universe since the time of Galileo and Kepler is nearing the end of the line. "I worry whether we've come to the limits of empirical science," says Lawrence Krauss of Arizona State University. Specifically, Krauss wonders if it will require knowledge of other universes, such as those posed by Carroll, to understand why our universe is the way it is. If such knowledge is impossible to access, it may spell the end for deepening our understanding any further.

Turok says that's exactly why the Perimeter Institute exists, to harness the thinking of the world's brightest young minds in an unrestrained environment. By optimising conditions for creative thinking, it may be possible to avoid such an impasse.

"We're used to thinking of theoretical physics as accidental," says Turok. "We need to ask whether there's a more strategic way to speed up understanding and discovery."

Perhaps then all those troubled physicists can finally get some rest – or at least switch to more mundane worries.

The "Quantum to Cosmos" festival can be viewed online

Our Global Ponzi Economy

October 07, 2009

Lester R. Brown

Our mismanaged world economy today has many of the characteristics of a Ponzi scheme. A Ponzi scheme takes payments from a broad base of investors and uses these to pay off returns. It creates the illusion that it is providing a highly attractive rate of return on investment as a result of savvy investment decisions when in fact these irresistibly high earnings are in part the result of consuming the asset base itself. A Ponzi scheme investment fund can last only as long as the flow of new investments is sufficient to sustain the high rates of return paid out to previous investors. When this is no longer possible, the scheme collapses—just as Bernard Madoff’s $65-billion investment fund did in December 2008.

Although the functioning of the global economy and a Ponzi investment scheme are not entirely analogous, there are some disturbing parallels. As recently as 1950 or so, the world economy was living more or less within its means, consuming only the sustai nable yield, the interest of the natural systems that support it. But then as the economy doubled, and doubled again, and yet again, multiplying eightfold, it began to outrun sustainable yields and to consume the asset base itself.

In a 2002 study published by the U.S. National Academy of Sciences, a team of scientists concluded that humanity’s collective demands first surpassed the earth’s regenerative capacity around 1980. As of 2009 global demands on natural systems exceed their sustainable yield capacity by nearly 30 percent. This means we are meeting current demands in part by consuming the earth’s natural assets, setting the stage for an eventual Ponzi-type collapse when these assets are depleted.

As of mid-2009, nearly all the world’s major aquifers were being overpumped. We have more irrigation water than before the overpumping began, in true Ponzi fashion. We get the feeling that we’re doing very well in agriculture—but the realit y is that an estimated 400 million people are today being fed by overpumping, a process that is by definition short-term. With aquifers being depleted, this water-based food bubble is about to burst.

A similar situation exists with the melting of mountain glaciers. When glaciers first start to melt, flows in the rivers and the irrigation canals they feed are larger than before the melting started. But after a point, as smaller glaciers disappear and larger ones shrink, the amount of ice melt declines and the river flow diminishes. Thus we have two water-based Ponzi schemes running in parallel in agriculture.

And there are more such schemes. As human and livestock populations grow more or less apace, the rising demand for forage eventually exceeds the sustainable yield of grasslands. As a result, the grass deteriorates, leaving the land bare, allowing it to turn to desert. In this Ponzi scheme, herders are forced to rely on food aid or they migrate to cities.

Three fourths of oceanic fisheries are now being fished at or beyond capacity or are recovering from overexploitation. If we continue with business as usual, many of these fisheries will collapse. Overfishing, simply defined, means we are taking fish from the oceans faster than they can reproduce. The cod fishery off the coast of Newfoundland in Canada is a prime example of what can happen. Long one of the world’s most productive fisheries, it collapsed in the early 1990s and may never recover.

Paul Hawken, author of Blessed Unrest, puts it well: “At present we are stealing the future, selling it in the present, and calling it gross domestic product. We can just as easily have an economy that is based on healing the future instead of stealing it. We can either create assets for the future or take the assets of the future. One is called restoration and the other exploitation.” The larger question is, If we continue with business as usual— with overpumping, overgrazing, overplowing, overfishing, and overloading the atmosphere with carbon dioxide—how long will it be before the Ponzi economy unravels and collapses? No one knows. Our industrial civilization has not been here before.

Unlike Bernard Madoff’s Ponzi scheme, which was set up with the knowledge that it would eventually fall apart, our global Ponzi economy was not intended to collapse. It is on a collision path because of market forces, perverse incentives, and poorly chosen measures of progress.

In addition to consuming our asset base, we have devised some clever techniques for leaving costs off the books—much like the disgraced and bankrupt Texas-based energy company Enron did some years ago. For example, when we use electricity from a coal-fired power plant we get a monthly bill from the local utility. It includes the cost of mining coal, transporting it to the power plant, burning it, generating the electricity, and d elivering electricity to our homes. It does not, however, include any costs of the climate change caused by burning coal. That bill will come later—and it will likely be delivered to our children. Unfortunately for them, their bill for our coal use will be even larger than ours.

When Sir Nicholas Stern, former chief economist at the World Bank, released his groundbreaking 2006 study on the future costs of climate change, he talked about a massive market failure. He was referring to the failure of the market to incorporate the costs of climate change in the price of fossil fuels. According to Stern, the costs are measured in the trillions of dollars. The difference between the market prices for fossil fuels and an honest price that also incorporates their environmental costs to society is huge.

As economic decisionmakers we all depend on the market for information to guide us, but the market is giving us incomplete information, and as a result we are m aking bad decisions. One of the best examples of this can be seen in the United States, where the gasoline pump price was around $3 per gallon in mid-2009. This reflects only the cost of finding the oil, pumping it to the surface, refining it into gasoline, and delivering the gas to service stations. It overlooks the costs of climate change as well as the costs of tax subsidies to the oil industry, the burgeoning military costs of protecting access to oil in the politically unstable Middle East, and the health care costs of treating respiratory illnesses caused by breathing polluted air. These indirect costs now total some $12 per gallon. In reality, burning gasoline is very costly, but the market tells us it is cheap.

The market also does not respect the carrying capacity of natural systems. For example, if a fishery is being continuously overfished, the catch eventually will begin to shrink and prices will rise, encouraging even more investment in fishing trawle rs. The inevitable result is a precipitous decline in the catch and the collapse of the fishery.

Today we need a realistic view about the relationship between the economy and the environment. We also need, more than ever before, political leaders who can see the big picture. And since the principal advisors to government are economists, we need either economists who can think like ecologists or more ecological advisors. Otherwise, market behavior—including its failure to include the indirect costs of goods and services, to value nature’s services, and to respect sustainable-yield thresholds—will cause the destruction of the economy’s natural support systems, and our global Ponzi scheme will fall apart.