Brain activity map

The biggest news for neuroscientists in President Obama’s State of the Union Address was the announcement of the Brain Activity Map (BAM) project (e.g. see here and here). The goal of this project as outlined in this Neuron paper is to develop the technological capability to measure the spiking activity of every single neuron in the brain simultaneously. I used to fantasize about such a project a decade ago but now I’m more ambivalent. Although the details of the project have not been announced, people involved are hoping for 300 million dollars per year for ten years. I do believe that a lot will be learned in pursuing such a project but it may also divert resources for neuroscience towards this one goal. Given that the project is mostly technological, it may also mostly bring in new engineers and physicists to neuroscience rather than fund current labs. It could be a huge boon for computational neuroscience because the amount of data that will be recorded will be enormous. It will take a lot of effort just to curate this data much less try to analyze and makes sense of it. Finally, on a cautionary note, it could be that much of the data will be superfluous. After all, we understand how gases behave (at least enough to design refrigerators and airplanes, etc.) without measuring the positions and velocities of every molecule in a room. I’m not sure we would have figured out the ideal gas law, the Carnot cycle, or the three laws of thermodynamics if we just relied on an “Air Activity Map Project” a century ago. There is probably a lot of compression going on in the brain. If we knew how this compression worked, we could then just measure the nonredundant information. That would certainly make the BAM project a whole lot easier.

Minimum wage and the efficient market

The current debate about the effect of raising the minimum wage on employment poses an interesting question about how efficient the labour market is. According to the classical view of economics (and the Freshwater school) raising the minimum wage should decrease the number of people working because it will induce employers to shed workers to minimize costs. However, multiple studies of the effects of minimum wages seem to show that small changes do not decrease employment and sometimes even increases it (e.g. see here). If people were completely rational, equally competent and the market were efficient then raising wages should decrease employment. If it turns out that this does not happen then one or more of these assumptions is false. My take is that they are all suspect.

According to basic economics theory, the wages employers offer is set by the marginal cost of adding an additional worker. This means that they will select a wage such that the productivity gains for the last worker they hire is balanced by the cost of that worker. However, this assumes that there is a readily available pool of workers willing to take that wage and that the productivity of a worker is independent of the wage offered. Neither of these assumptions may be true. The argument of the Freshwater school is that during times of high unemployment there should be lots of people willing to take jobs at any wage. However,  there is likely to be a distribution for the lowest acceptable wage. In fact, Keynesian theory is predicated on the fact that wages and prices are ‘sticky’ so in an economic downturn, neither fall fast enough for the market to clear. A person is probably unwilling to take a lower paying job because it may affect her prospects of securing a higher paying one in the future when the economy rebounds. Hence, employers attempt to set a wage at some point on the lower tail of the acceptable wage distribution so that the cost of waiting to find someone willing to take that wage plus the cost of hiring is balanced by the expected increase in sales. Increasing the minimum wage could then actually increase employment by forcing employers to hire at a wage point where the wait time is much shorter. The savings from the shortened wait time and possibly lower turnover balances the cost of the higher wage.

Employment may also increase if productivity scales with the lowest acceptable wage.  By forcing employers to pay a higher wage, they may actually hire much more productive workers that increases sales enough to hire another worker. In fact, the employers may not even realize that increasing the offered wage would actually increase sales because they never sampled that part of the distribution. They could be stuck in a local minimum where they offer low wages to low productivity workers when they could have offered slightly higher wages to much higher productivity workers. In that scenario, the minimum wage would actually benefit the employers more than the employees.

Both of these situations are plausible indications of a market failure in the labour market. The market may be locally efficient in that the wages are optimal for small changes but not globally efficient in that there could be another more efficient fixed point somewhere far away on the wage curve. Government intervention could actually push the market to a more efficient point and this is not even accounting for the fact that the increased wages would be spent, which could cause a Keynesian multiplier boost to the economy. This is not to suggest that the government knows any better than the employers but just that unintended consequences can go both ways.


Since the putative discovery of the Higgs boson this past summer, I have heard and read multiple attempts at explaining what exactly this discovery means. They usually go along the lines of “The Higgs mechanism gives mass to particles by acting like molasses in which particles move around …” More sophisticated accounts will then attempt to explain that the Higgs boson is an excitation in the Higgs field. However, most of the explanations I have encountered assume that most people already know what mass actually is and why particles need to be endowed with it. Given that my seventh grade science teacher didn’t really understand what mass was, I have a feeling that most nonphysicists don’t really have a full appreciation of mass.

To start out, there are actually two kinds of mass. There is inertial mass, which is the resistance to acceleration and is mass that goes into Newton’s second law of  F = m a and then there is gravitational mass which is like the “charge” of gravity. The more gravitational mass you have the stronger the gravitational force. Although they didn’t need to be, these two masses happen to be the same.  The equivalence of inertial and gravitational mass is one of the deepest facts of the universe and is the reason that all objects fall at the same rate. Galileo’s apocryphal Leaning Tower of Pisa experiment was a proof that the two masses are the same. You can see this by noting that the gravitational force is given by

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