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September 4, 2010

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Stephen Hawking's Big Bang Gaps

Posted: 04 Sep 2010 01:11 AM PDT

I probably should have posted this discussion of naked CDS from Yeon-Koo Che and Rajiv Sethi, but for some reason I felt like something different from the usual fare:

Stephen Hawking's big bang gaps, by Paul Davies, CIF: Cosmologists are agreed that the universe began with a big bang 13.7 billion years ago. People naturally want to know what caused it. A simple answer is nothing: not because there was a mysterious state of nothing before the big bang, but because time itself began then – that is, there was no time "before" the big bang. The idea is by no means new. In the fifth century, St Augustine of Hippo wrote that "the universe was created with time and not in time".
Religious people often feel tricked by this logic. They envisage a miracle-working God dwelling within the stream of time for all eternity and then, for some inscrutable reason, making a universe (perhaps in a spectacular explosion) at a specific moment in history.
That was not Augustine's God, who transcended both space and time. Nor is it the God favored by many contemporary theologians. In fact, they long ago coined a term for it – "god-of-the-gaps" – to deride the idea that when science leaves something out of account, then God should be invoked to plug the gap. The origin of life and the origin of consciousness are favorite loci for a god-of-the-gaps, but the origin of the universe is the perennial big gap.
In his new book, Stephen Hawking reiterates that there is no big gap in the scientific account of the big bang. The laws of physics can explain, he says, how a universe of space, time and matter could emerge spontaneously, without the need for God. And most cosmologists agree: we don't need a god-of-the-gaps to make the big bang go bang. It can happen as part of a natural process. A much tougher problem now looms, however. What is the source of those ingenious laws that enable a universe to pop into being from nothing?
Traditionally, scientists have supposed that the laws of physics were simply imprinted on the universe at its birth, like a maker's mark. As to their origin, well, that was left unexplained.
In recent years, cosmologists have shifted position somewhat. If the origin of the universe was a law rather than a supernatural event, then the same laws could presumably operate to bring other universes into being. The favored view now, and the one that Hawking shares, is that there were in fact many bangs, scattered through space and time, and many universes emerging therefrom, all perfectly naturally. The entire assemblage goes by the name of the multiverse.
Our universe is just one infinitesimal component amid this vast – probably infinite – multiverse, that itself had no origin in time. So according to this new cosmological theory, there was something before the big bang after all – a region of the multiverse pregnant with universe-sprouting potential.
A refinement of the multiverse scenario is that each new universe comes complete with its very own laws – or bylaws, to use the apt description of the cosmologist Martin Rees. Go to another universe, and you would find different bylaws applying. An appealing feature of variegated bylaws is that they explain why our particular universe is uncannily bio-friendly; change our bylaws just a little bit and life would probably be impossible. The fact that we observe a universe "fine-tuned" for life is then no surprise: the more numerous bio-hostile universes are sterile and so go unseen.
So is that the end of the story? Can the multiverse provide a complete and closed account of all physical existence? Not quite. The multiverse comes with a lot of baggage, such as an overarching space and time to host all those bangs, a universe-generating mechanism to trigger them, physical fields to populate the universes with material stuff, and a selection of forces to make things happen. Cosmologists embrace these features by envisaging sweeping "meta-laws" that pervade the multiverse and spawn specific bylaws on a universe-by-universe basis. The meta-laws themselves remain unexplained – eternal, immutable transcendent entities that just happen to exist and must simply be accepted as given. In that respect the meta-laws have a similar status to an unexplained transcendent god.
According to folklore the French physicist Pierre Laplace, when asked by Napoleon where God fitted into his mathematical account of the universe, replied: "I had no need of that hypothesis." Although cosmology has advanced enormously since the time of Laplace, the situation remains the same: there is no compelling need for a supernatural being or prime mover to start the universe off. But when it comes to the laws that explain the big bang, we are in murkier waters.

links for 2010-09-03

Posted: 03 Sep 2010 11:02 PM PDT

"Optimism…Pessimism…and a Bit of Perspective"

Posted: 03 Sep 2010 03:17 PM PDT

Dennis Lockhart, president of the Atlanta Fed, makes it clear that presently he sees no need for more stimulus -- a slow, plodding recovery like we had in the previous two recession is the best we can expect. If we're on track to match those, there's no need to try to do better.

Here's David Altig of the Atlanta Fed discussing Lockhart's speech earlier today:

Optimism…pessimism…and a bit of perspective, by David Altig, macroblog: Here's how I'm tempted to summarize today's release of the August employment report from the U.S. Bureau of Labor Statistics: more of the same. That theme fits nicely with comments this morning from Atlanta Fed President Dennis Lockhart, in a speech at East Tennessee State University. Here he calls for a little perspective:

"Some commentators are reading recent economic data as suggesting the onset of a second recession and deflationary cycle. Quite naturally, business people and consumers aren't sure what to believe.

"At the last meeting of the Federal Open Market Committee (FOMC) in Washington, the committee made a decision that has been widely interpreted as signaling declining confidence in the strength and sustainability of the recovery….

"In my remarks today, I will provide a less alarmist interpretation of recent economic information and the Fed's recent policy decision. I will argue that, generally speaking, there was too much optimism in the early months and quarters of the recovery and now there may be excessive pessimism."

One point is that recoveries are not generally linear affairs:

"Growth at the end of last year and early part of this year was stronger than I anticipated while economic activity in the second and third quarters seems weaker than I expected.

"But such ups and downs are not unusual during a recovery. A little history: following the 2001 recession, gross domestic product (GDP) grew at the annualized rate of 3.5 percent in early 2002. Growth then decelerated to about 2 percent for the next two quarters then fell to almost zero in the fourth quarter. Entering 2003, growth edged up to a little over 1.5 percent and then accelerated from there to a sustained period of relatively strong growth for two years."

...Even in the rapid-growth, pre-1990 recoveries, there was generally a quarter or two of growth that underperformed. ...

But the better benchmarks will likely prove to be the slower-growth, low-employment recoveries post-1990. In addition to the 2001 experience noted by President Lockhart, the expansion that followed the 1990–91 recession stumbled along with quarterly growth rates of 2.7, 1.69, and 1.58 percent, before picking up to above-potential growth rates. Despite that, the eighth quarter after that recession's end clocked in at an anemic 0.75 percent.

So why are we content to match that performance instead of trying to improve? Why do we try to rationalize concerns instead (calling it "a bit of perspective")?:

What is more important is that there is a reasonably good explanation for why we might have hit a soft patch:

"Looking at the 2009–2010 recovery, it seems clear that some of the early strength was promoted by policies that pulled forward spending from the second and third quarters of this year. The recent sharp decline in housing-related indicators following the expiration of homebuyer tax credits is the most obvious example of this effect."

Given that expectation, wouldn't it have been nice to have someone, the Fed say, try to fill this hole until the private sector begins growing robustly on its own?

Back to David Altig:

Essentially, President Lockhart's is a simple message: don't ignore the short-term data, but be careful with getting too carried away with it as well.

"Simply stated, I was expecting a relatively modest recovery...

And he, along with other members of the Fed, is apparently content with that. Finally:

...with respect to that meeting, here is the main policy point:

"At the last meeting there were two important considerations as I saw it. First, as already discussed, some economic data came in weaker than expected, shifting the balance of risks to slower growth in the near term and further disinflation. Second, the Fed's holdings of MBS were projected to decline faster than previously thought because lower rates were generating heavy mortgage prepayments and refinancings.

"So, in the context of a softening economy, the FOMC was confronted with the prospect of unintended withdrawal of support for the recovery through a decline in the level of liquidity provided to the economy….

"That is how I interpret the decision announced following the August meeting—a small tactical change designed to preserve the level of liquidity provided to the system. I supported the committee's decision, but I do not view it as a fundamental change of outlook or strategy. I do not believe this change necessarily heralds the beginning of a period of further expansion of the Fed's balance sheet. Nor do I think the decision precludes a return to a policy of allowing the balance sheet to shrink on its own.

"I think the decision has been over-interpreted in some quarters."


So, again, the recovery is expected to plod along like we've seen in the past, at least that's the hope, and though the downside risk has increased and the Fed has the tools to try to help, it doesn't think it should use them.

My view is different.

Will a Payroll Tax Cut Stimulate the Economy?

Posted: 03 Sep 2010 12:33 PM PDT

Will a payroll tax cut stimulate the economy? I am going to answer this in the context of  Gauti B. Eggertsson' paper "What Fiscal Policy Is Effective at Zero Interest Rates?" where this question is addressed directly (the analysis begins on page 13). The model is New Keynesian.

The answer, in this model anyway, is that in normal times a payroll tax cut would be stimulative, but at the zero bound it's not so clear. Let me see if I can explain why.

When interest rates are positive, the framework is essentially a standard AS-AD model:


A payroll tax cut increases labor supply and shifts out the AS curve. The shift in the AS curve results in lower inflation and higher output/employment.

One thing that is left out of this model to simplify the analysis and keep it tractable is the demand-side effects of such policies. That is, a tax cut would also increase AD. If we add this effect, the graph then looks like:


Output goes up even more, but whether inflation goes up or down depends upon which shift is larger, the shift in the AS or the shift in the AD (based upon the evidence on how labor supply responds to changes in taxes, I would expect that the shift in the AD would be larger, but ultimately that is an empirical matter).

When the economy is at the zero bound for nominal interest rates things change. In particular, the AD curve slopes upward. This will be explained intuitively in a moment, but mechanically the effect of a positively sloped AD curve is as follows:


Thus, when we consider only the supply-side effects of a tax cut, it has a negative impact on output and employment. Why is this?

Figure 5 clarifies the intuition for why labor tax cuts become contractionary at zero interest rates while being expansionary under normal circumstances. The key is aggregate demand. At positive interest rates the AD curve is downward-sloping in inflation. The reason is that as inflation decreases, the central bank will cut the nominal interest rate more than 1 to 1 with inflation..., which is the Taylor principle... Similarly, if inflation increases, the central bank will increase the nominal interest rate more than 1 to 1 with inflation, thus causing an output contraction with higher inflation. As a consequence, the real interest rate will decrease with deflationary pressures and expanding output, because any reduction in inflation will be met by a more than proportional change in the nominal interest rate. This, however, is no longer the case at zero interest rates, because interest rates can no longer be cut. This means that the central bank will no longer be able to offset deflationary pressures with aggressive interest rate cuts, shifting the AD curve from downward-sloping to upward-sloping in (YL,πL) space...
The reason is that lower inflation will now mean a higher real rate, because the reduction in inflation can no longer be offset by interest rate cuts. Similarly, an increase in inflation is now expansionary because the increase in inflation will no longer be offset by an increase in the nominal interest rate; hence, higher inflation implies lower real interest rates and thus higher demand.

Once again, however, demand side effects are missing. Tacking those on gives:


Thus, the overall effect on employment depends upon the net effect of the AD and AS shifts. If the AD shift dominates, as I suspect it would, it's still possible for this policy to have positive effects on output and employment. But the size of the effect depends upon the strength of the demand side shift, and how strong the shift would be is an open question, particularly given the degree of household balance sheet rebuilding we are seeing which causes the tax cuts to be saved rather than spent.

Another way to think about this is the following. Supply is not the problem right now, it's lack of demand, and a policy that encourages more supply and threatens deflation is not helpful except to the extent that it increases aggregate demand in the process. Other types of policies can avoid this problem, see, for example the sales tax cut discussed on page 20 or the discussion of fiscal policy multipliers on page 17, but they may not have the same political feasibility as  tax cut for labor, which itself doesn't seem all that likely give the degree of opposition it will likely hit in Congress (the sales tax cut would be difficult to implement given that sales taxes are levied at the state level, and there's no chance that government spending increases will pass Congress right now; on the politics of a payroll tax cut, see the end of this post).


[Note: The demand-side effects were left out of the paper to keep the mathematics tractable, and it may be that simply tacking on the demand-side effects as I've done (the red lines) isn't quite correct. I think it's okay, but if anyone can speak to this, that would be great. Also, the policy analyzed in the paper is best interpreted as a payroll tax cut on the worker side. I don't think it matters if the cut is on the employer side, and I hope the administration doesn't pursue this anyway since the employer side tax cut may not pass through to labor fully, or much at all in the very short-run, but, again, if that matters and someone can speak to this point, please do.]

The Employment Report: “We’ve Gone Essentially Nowhere in a Year”

Posted: 03 Sep 2010 09:35 AM PDT

Here's my somewhat cranky response this morning's employment report showing that the unemployment rate ticked up, and that the broader U-6 measure went up even more. There was some private sector job growth, but not nearly enough to keep up with population growth, and far from enough to make any inroads into reemploying the millions of people who have lost jobs:

The Employment Report: "We've Gone Essentially Nowhere in a Year"

My fear isn't a double dip as much as it is that job and GDP growth will remain stagnant. The central valley in California is a good metaphor. It's narrow east to west, but very long north to south (think of the shape of the state). We went down into the valley as we went into the recession, and the question for me has always been whether we are heading east to west so that we will climb out of the valley relatively quickly, or north to south as we trudge along at the bottom of the valley for considerable time before finally climbing slowly back to full employment. I've been warning for a long time that it looks like north to south, and the fact that we've had essentially no growth for a year now, and no hint of change any time soon, makes the north to south fear very real. The administration is supposed to propose new policies to try to help us reach the other side faster, but the timing of that effort -- way too late except as a political ploy -- is one of the thing's I'm cranky about.

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