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Archive for May 2005

Short the real estate bubble!

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Blogger Mark Kleiman, who lives in LA, did. What if you don’t have a house in a bubble market? Well, now you can buy and sell derivative contracts based on median sales prices of existing single-family homes, as released each quarter by the National Association of Realtors (NAR). Available markets include NYC, Chicago, SF, LA, SD and Miami.

The problem is, it’s the smart money (short interest) looking at these new derivatives. The dumb money is out there flipping houses with no-interest mortgages! In addition, it may take a few years or more for this bubble to deflate…

Written by infoproc

May 31, 2005 at 4:31 pm

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Price to rent ratios II

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This San Francisco Federal Reserve report shows data going back to 1982. The current period is clearly anomalous (it recalls P/E ratios during the tech bubble 1995-2000). I expect to see a repeat of the bump seen earlier in the late 1980s to early 1990s; note the inevitable reversion to the mean. It won’t be pretty given new phenomena like zero-interest and sub-prime mortgages, and home equity loans. (Compare to Japan’s 20 year housing bubble, discussed in an earlier post. Ours may take another decade to unwind as well.)

Below is some data recently published in the Times. Note the nationwide uniformity of price-rent ratios in 2000, as opposed to today. The bay area leads the nation with a ratio that has almost tripled in the last 5 years.

It is possible that replacing home price by monthly mortgage payment in the numerator would account for most of the 2000-2005 increase in national average price-rent (from 11.6 to 17.1), but this doesn’t come close to explaining the frothier regions on the coasts.

Written by infoproc

May 30, 2005 at 4:46 pm

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"Three billion new surfers on the wave of globalization"

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Clyde Prestowitz’s new book Three Billion New Capitalists: The Great Shift of Wealth and Power to the East is a more thoughtful, less breathless, version of Tom Friedman’s The World is Flat.

Prestowitz discusses at length the advantages and disadvantages of globalization and free trade. His is the first popular book I know of to cite the work of Baumol and Gomory on problems with the usual Ricardian arguments of comparative advantage (see also this article by Samuelson). Prestowitz draws on his background as a trade negotiator in the Reagan administration to find real world examples which deviate drastically from the usual efficient market assumptions, including cases involving Japanese companies dumping their products in the US, and later raising prices once American competitors are eliminated.

Prestowitz advocates government support of R&D, as well as occasional intervention in markets. However, he doesn’t seem to understand that while government intervention can lead to better outcomes, it may not on average do better than the market left to its own devices. See Samuelson for a nice discussion of this point.

Written by infoproc

May 26, 2005 at 8:20 pm

Posted in globalization

Wormholes, NEC and all that

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The BBC and New Scientist articles seem to have generated a lot of interest in this topic. Odd how my colleagues can hear me loudly discussing this stuff for six months with my postdoc and grad student, but only after the BBC decides to write about it do they want to know more 🙂

The original papers are listed below. Both have been revised since posting on arxiv.org – if you want a more up to date version please contact me.

http://arxiv.org/abs/hep-th/0504003 (wormholes)
http://arxiv.org/abs/hep-th/0502203 (instability and NEC)

There is a longer version of the instability analysis forthcoming, by Buniy, Hsu and Murray.

Let me make some comments here for physics readers:

1) Our original interest was in dark energy. The observational data suggest (although not strongly – see comments) that w = p/rho < -1, which violates various energy conditions. We wanted to understand how easy or hard it is to build models with w < -1. With some collaborators at Caltech, I had obtained a result in classical scalar models that w < -1 implies instability. We wanted to generalize this result.

2) Our strongest results are in the contexts of classical field theory (including both gauge and scalar fields) and perfect fluids. There is a quantum loophole involving renormalization that allows for small violations of the NEC (well-known examples are the Casimir effect and black hole spacetimes).

3) When applying this to wormholes, we are considering the exotic (NEC-violating) matter necessary to stabilize the wormhole. This matter must have large energy-momentum tensor T_mn. We focus on wormholes which have nearly-classical spacetimes (the other type is less useful for Sci Fi). We show that this condition is strong enough to require that the exotic matter evolves semi-classically – i.e., it is subject to our results in classical field theory.

4) Some readers (esp. from the relativity community) have misinterpreted our results as claiming that the Casimir or black hole vacuum is unstable, but this is not the case (see point (2) above). In the wormhole case, the key point is that semi-classical wormholes cannot result from exotic matter which violates the NEC via quantum effects.

Written by infoproc

May 24, 2005 at 5:26 pm

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BBC on wormholes

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We get a mention in this nice BBC article. Here is the latest version (PDF) of the talk Roman Buniy will give on Tuesday at a conference at Vanderbilt.

Wormhole ‘no use’ for time travel
By Paul Rincon
BBC News science reporter

Artist’s impression of a wormhole Image: SPL
Wormholes contort the fabric of the Universe
For budding time travellers, the future (or should that be the past?) is starting to look bleak.

Hypothetical tunnels called wormholes once looked like the best bet for constructing a real time machine.

These cosmic shortcuts, which link one point in the Universe to another, are favoured by science fiction writers as a means both of explaining time travel and of circumventing the limitations imposed by the speed of light.

The concept of wormholes will be familiar to anyone who has watched the TV programmes Farscape, Stargate SG1 and Star Trek: Deep Space Nine.

The opening sequence of the BBC’s new Doctor Who series shows the Tardis hurtling through a “vortex” that suspiciously resembles a wormhole – although the Doctor’s preferred method of travel is not explained in detail.

But the idea of building these so-called traversable wormholes is looking increasingly shaky, according to two new scientific analyses.

Remote connection

A common analogy used to visualise these phenomena involves marking two holes at opposite ends of a sheet of paper, to represent distant points in the Universe. One can then bend the paper over so that the two remote points are positioned on top of each other.

[The wormholes] you would like to build – the predictable ones where you can say Mr Spock will land in New York at 2pm on this day – those look like they will fall apart
Stephen Hsu, University of Oregon
If it were possible to contort space-time in this way, a person might step through a wormhole and emerge at a remote time or distant location.

The person would pass through a region of the wormhole called the throat, which flares out on either side.

According to one idea, a wormhole could be kept open by filling its throat, or the region around it, with an ingredient called exotic matter.

This is strange stuff indeed, and explaining it requires scientists to look beyond the laws of classical physics to the world of quantum mechanics.

Exotic matter is repelled, rather than attracted, by gravity and is said to have negative energy – meaning it has even less than empty space.

Law breaker

But according to a new study by Stephen Hsu and Roman Buniy, of the University of Oregon, US, this method of building a traversable wormhole may be fatally flawed. In a paper published on the arXiv pre-print server, the authors looked at a kind of wormhole in which the space-time “tube” shows only weak deviations from the laws of classical physics.

These “semi-classical” wormholes are the most desirable type for time travel because they potentially allow travellers to predict where and when they would emerge.

The Tardis (BBC)
The concept is a favourite of science fiction writers
Wormholes entirely governed by the laws of quantum mechanics, on the other hand, would likely transport their payloads to an undesired time and place.

Calculations by the Oregon researchers show a wormhole that combines exotic matter with semi-classical space-time would be fundamentally unstable.

This result relies in part on a previous paper in which Hsu and Buniy argued that systems which violate a physical principle known as the null energy condition become unstable.

“We aren’t saying you can’t build a wormhole. But the ones you would like to build – the predictable ones where you can say Mr Spock will land in New York at 2pm on this day – those look like they will fall apart,” Dr Hsu said.

Tight squeeze

A separate study by Chris Fewster, of the University of York, UK, and Thomas Roman, of Central Connecticut State University, US, takes a different approach to tackling the question of wormholes.

Amongst other things, their analysis deals with the proposal that wormhole throats could be kept open using arbitrarily small amounts of exotic matter.

Fewster and Roman calculated that, even if it were possible to build such a wormhole, its throat would probably be too small for time travel.

It might – in theory – be possible to carefully fine-tune the geometry of the wormhole so that the wormhole throat became big enough for a person to fit through, says Fewster.

But building a wormhole with a throat radius big enough to just fit a proton would require fine-tuning to within one part in 10 to the power of 30. A human-sized wormhole would require fine-tuning to within one part in 10 to the power of 60.

“Frankly no engineer is going to be able to do that,” said the York researcher.

The authors are currently preparing a manuscript for publication.

Supporting view

However, there is still support for the idea of traversable wormholes in the scientific community. One physicist told BBC News they could see problems with Hsu’s and Buniy’s conclusions.

“Violations of the null energy condition are known to occur in a number of situations. And their argument would prohibit any violation of it,” they commented.

“If that’s true, then don’t worry about Hawking radiation from a black hole; the entire black hole vacuum becomes unstable.”

The underlying physics was not in doubt, the researcher argued. The real challenge was in explaining how to engineer wormholes big enough to be of practical use.

Cambridge astrophysicist Stephen Hawking is amongst those researchers who have pondered the question of wormholes.

In the 1980s, he argued that something fundamental in the laws of physics would prevent wormholes being used for time travel. This idea forms the basis of Hawking’s Chronology Protection Conjecture.

Written by infoproc

May 23, 2005 at 8:54 pm

Posted in Uncategorized

PIMCO bullish on long bonds?

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In his latest commentary, Bill Gross of PIMCO (perhaps the most influential bond trader in the world) comes very close to sounding bullish on long bonds. This is a rather amazing turnaround, since over the last couple of years he has been warning repeatedly about an interest rate meltdown.

Gross now seems convinced that our Bretton Woods II currency regime will survive another 3-5 years, and that the dominant trend is deflation exported from China. He reasons that several years of nearly zero (real) interest rates have failed to produce significant inflation in the US economy. Thus, once the stimulative effect of low interest rates goes away, we are in for a period of deflation, which will be kind to bonds – he is bold enough to predict 10 year yield as low as 3%!

Gross: “Future finance-based consumption, however, is limited by our ability to keep pumping lower and lower yields, which in the past have led to higher and higher TIPS, home, stock, and associated asset prices. Let me do the TIPS math for you and then you can draw the implications for other asset classes. The 14% 5-year TIPS capital gain over the past few years that Alan Greenspan has been able to manufacture probably can only go up by 5 more points, because a 0% real yield for a 5-year maturity TIPS serves as a practical limit that investors will tolerate during deflationary, and most low inflationary environments. A 5-year TIPS moving lower in yield from 1% to 0% goes up 5 points. Even if the Fed continues to “Pump,” then, we are Âľ of the way complete in terms of the Fed’s ability to continue to stimulate asset prices, because its 21st century journey started at 4%, we are now at 1%, and 0% is the practical limit. That doesn’t mean that the housing “bubble” can’t keep going because it likely will if the Fed “Pumps” real yields closer to 0%. But there are limits, and we are heading down the home stretch of this U.S. race towards prosperity based on asset price appreciation.

Our point on the “Pump” then, is to suggest that in combination with a globalized free trade-based economy exhibiting a surfeit of cheap Asian labor, it will be difficult to generate U.S. inflation higher than our current 3% even if interest rates fall further. If 3% inflation is all we can get from the past 5-years’ asset inflation, it’s hard to believe that we get more from what’s left. The potential to reflate via interest rates is nearly over. We draw the same conclusion for Euroland and Japan. Japan, of course, is the primary example of how 0% nominal yields can fail to generate any inflation whatsoever, is it not? Continued disinflation not reflation, then, will rule our fragile future kingdom, with the potential for 1-2% CPI prints in most years between 2006 and 2010 throughout much of the global economy. Readers may remember our past few years’ Secular Forum descriptions of the tug-of-war between disinflation and reflationary forces. We have proclaimed a winner based on our observation of massive fiscal and monetary global stimulation described above, the limited inflationary response, and the lack of further ammunition. Long live our disinflationary King.

If we had to forecast (and we do), we believe a range of 3 – 4½% for 10-year nominal Treasuries will prevail during most of our secular timeframe…”

Written by infoproc

May 21, 2005 at 12:33 am

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Cloning has arrived…

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While the US sleeps, leading-edge stem cell research is being done at Seoul National University. (Well, at least California has woken up and is trying to counter the Bush administration’s lack of support for stem cell research by using state funds.)

The Korean lab can produce one clone per 17 donor eggs. That means the cost per clone is similar to that of an IVF cycle – or less than $5k. I imagine in a decade wealthy people (perhaps everyone?) will have access to a supply of their own stem cells. Also, women who are past reproductive age could choose to have a clone child, using their own or a relative or friend’s genetic material.

Of course, some US religious fundamentalists (like our president) will fight these developments. Are we ready for the coming clone war?

NYT: “In what scientists say is a stunning leap forward, a team of South Korean researchers has developed a highly efficient recipe for producing human embryos by cloning and then extracting their stem cells.

Writing today in the journal Science, they report that they used their method to produce 11 human stem cells lines that are genetic matches of 11 patients aged 2 to 56.

Previously, the same group, led by Dr. Woo Suk Hwang and Dr. Shin Yong Moon of Seoul National University, produced a single stem cell line from a cloned embryo, but the process was so onerous that scientists said it was not worth trying to repeat it, and some doubted the South Koreans’ report was even correct.

Now things have changed.

“It is a tremendous advance,” said Dr. Leonard Zon, a stem cell researcher at Harvard Medical School and president of the International Society for Stem Cell Research, who was not involved in the research.

The method, called therapeutic cloning, is one of the great hopes of the stem cell field. It produces stem cells, universal cells that are extracted from embryos, killing the embryos in the process, and, in theory, can be directed to grow into any of the body’s cell types. And since the stem cells come from embryos that are clones of individuals, they should be exact genetic matches. Scientists want to obtain such stem cells from patients to study the origin of diseases and to develop replacement cells that would be identical to ones a patient has lost.

…But this time, with a handful of technical improvements that mostly involved such things as methods for growing cells and breaking open embryos, they used an average of 17 eggs per stem cell line and could almost guarantee success with a single woman’s eggs obtained in a single month. And it did not matter if the patient whose cells were being cloned was young or middle aged, male or female, sick or well – the process worked.

“You almost have no reason not to do it,” said Dr. Davor Solter, the director of the Max Planck Institute for Immunobiology in Freiberg, Germany.

In fact, Dr. Solter added, it now looks like it is much more efficient to clone and obtain human stem cells than it is to do the same experiment in animals.”

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May 19, 2005 at 6:35 pm

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Bubble reaches Eugene

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The other day I discovered a new development of big (3-4,000 sq ft.), expensive ($500-800k) houses in the SW hills of Eugene. Apparently there are others like it around the outskirts of our urban growth boundary. Five years ago you could have bought a house of that size for $300-400k. I was kind of surprised, as neither population nor income growth have been very large here in the last few years. Home prices were pretty flat here around 2000, and only recently accelerated. A realtor told me that “the market here is just so strong… it has nowhere to go but up!”

But, later she said “My husband and I worked our whole lives, and we can’t afford any of these houses… Where do people get the money?”

Well, here’s how:

WSJ: “More and more Americans are turning to debt to pay for lifestyles their current incomes can’t support. They are determined to live better than their parents, seduced by TV shows like “The O.C.” and “Desperate Housewives,” which take upper-class life for granted, and bombarded with advertisements for expensive automobiles and big-screen TVs. Financial firms have turned credit for the masses into a huge business, aided by better technology for analyzing credit risks. For Americans who aren’t getting a big boost from workplace raises, easy credit offers a way to get ahead, at least for the moment…

Utah vividly illustrates the changes credit has wrought in the U.S. Last year, 28 of every 1,000 Utah households filed for bankruptcy, twice the national average and nearly triple Utah’s rate a decade earlier, according to Economy.com, a West Chester, Pa., consulting firm. Utahns often get married early and have the largest families in the nation on average. That makes for a lot of young parents with modest incomes looking for big homes and cars. The median monthly mortgage payment in Utah equaled 45.3% of a worker’s average monthly income in 2002, the fourth-highest level in the nation, according to the Utah Foundation, a Salt Lake City think tank.”

Written by infoproc

May 17, 2005 at 4:16 pm

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Credit derivatives and volatility

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Longtime readers of this blog know I have been puzzled over low implied volatility in equity markets over the last year or so. Recently we’ve had a spike in volatility (see the VIX index which tracks implied vol on the SP500), and this recent PIMCO report on credit derivatives suggests one explanation for recent behavior (CDS = credit default swaps; credit derivatives are valued by assuming a link between the volatility of the stock (e.g. GM) and the probability of default on the corporate debt (credit risk), hence the correlation trade strategy B described below):

“Interestingly, hedge funds are the largest users of credit derivatives and CDS. Several of the largest Wall Street firms estimate that 50-60% of their current trading volume in CDS is with hedge funds. These leveraged funds use CDX index products to gain a diversified exposure to credit, thus earning positive carry. Two trades, which have been popular with hedge funds, are long CDX index products/short individual CDS names (Strategy A) and long CDX index products/short equity calls (Strategy B).

…Strategy B is an income generation strategy (which is also being implemented by $10 billion closed-end income generation funds started in the past year). This strategy seeks to produce income via long exposure to spread product, yet gives up any large equity upside by selling calls. Both hedge funds and closed-end funds have been aggressive sellers of equity call options over the past year, suppressing implied equity volatility. This created an illusion of calm waters. However, as soon as equities fell and volatility spiked, these calm waters got surprisingly rough in a short amount of time as investors shifted into “risk reduction” mode and unwound long credit positions, bought equity put options and bought protection on CDX index products. This leveraged unwind trade caused credit spreads to widen sharply, put downward pressure on stocks and caused implied volatility on CDX options to spike.”

Written by infoproc

May 15, 2005 at 5:57 pm

Posted in globalization

Are we getting smarter? Why?

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It is well known that raw scores on IQ tests have been increasing at a rate of what would be about 3 IQ points per decade (the so-called Flynn effect). This means that, were the result of the test not rescaled so that the average is 100 by definition, the average IQ would have risen to 130 over the last century – i.e., the average person today scores better than all but 2 percent or so of the population in 1900. Malcolm Gladwell discusses this effect and its possible causes in this week’s New Yorker, reviewing a new book claiming that modern society, with its fast-paced multimedia entertainment (including video games, computers, TV, etc.) actually improves our cognitive skills.

Gladwell: “Twenty years ago, a political philosopher named James Flynn uncovered a curious fact. Americans—at least, as measured by I.Q. tests—were getting smarter. This fact had been obscured for years, because the people who give I.Q. tests continually recalibrate the scoring system to keep the average at 100. But if you took out the recalibration, Flynn found, I.Q. scores showed a steady upward trajectory, rising by about three points per decade, which means that a person whose I.Q. placed him in the top ten per cent of the American population in 1920 would today fall in the bottom third. Some of that effect, no doubt, is a simple by-product of economic progress: in the surge of prosperity during the middle part of the last century, people in the West became better fed, better educated, and more familiar with things like I.Q. tests. But, even as that wave of change has subsided, test scores have continued to rise—not just in America but all over the developed world. What’s more, the increases have not been confined to children who go to enriched day-care centers and private schools. The middle part of the curve—the people who have supposedly been suffering from a deteriorating public-school system and a steady diet of lowest-common-denominator television and mindless pop music—has increased just as much. What on earth is happening? In the wonderfully entertaining “Everything Bad Is Good for You” (Riverhead; $23.95), Steven Johnson proposes that what is making us smarter is precisely what we thought was making us dumber: popular culture.

…As Johnson points out, television is very different now from what it was thirty years ago. It’s harder. A typical episode of “Starsky and Hutch,” in the nineteen-seventies, followed an essentially linear path: two characters, engaged in a single story line, moving toward a decisive conclusion. To watch an episode of “Dallas” today is to be stunned by its glacial pace—by the arduous attempts to establish social relationships, by the excruciating simplicity of the plotline, by how obvious it was. A single episode of “The Sopranos,” by contrast, might follow five narrative threads, involving a dozen characters who weave in and out of the plot. Modern television also requires the viewer to do a lot of what Johnson calls “filling in,” as in a “Seinfeld” episode that subtly parodies the Kennedy assassination conspiracists, or a typical “Simpsons” episode, which may contain numerous allusions to politics or cinema or pop culture. The extraordinary amount of money now being made in the television aftermarket—DVD sales and syndication—means that the creators of television shows now have an incentive to make programming that can sustain two or three or four viewings.

…It doesn’t seem right, of course, that watching “24” or playing a video game could be as important cognitively as reading a book. Isn’t the extraordinary success of the “Harry Potter” novels better news for the culture than the equivalent success of “Grand Theft Auto III”? Johnson’s response is to imagine what cultural critics might have said had video games been invented hundreds of years ago, and only recently had something called the book been marketed aggressively to children: (Johnson) Reading books chronically understimulates the senses. Unlike the longstanding tradition of gameplaying—which engages the child in a vivid, three-dimensional world filled with moving images and musical sound-scapes, navigated and controlled with complex muscular movements—books are simply a barren string of words on the page. . . .

Books are also tragically isolating. While games have for many years engaged the young in complex social relationships with their peers, building and exploring worlds together, books force the child to sequester him or herself in a quiet space, shut off from interaction with other children. . . .

But perhaps the most dangerous property of these books is the fact that they follow a fixed linear path. You can’t control their narratives in any fashion—you simply sit back and have the story dictated to you. . . . This risks instilling a general passivity in our children, making them feel as though they’re powerless to change their circumstances. Reading is not an active, participatory process; it’s a submissive one.

He’s joking, of course, but only in part. The point is that books and video games represent two very different kinds of learning. When you read a biology textbook, the content of what you read is what matters. Reading is a form of explicit learning. When you play a video game, the value is in how it makes you think. Video games are an example of collateral learning, which is no less important.”

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May 13, 2005 at 2:48 pm

Posted in Uncategorized