Tuesday, March 20, 2018

Self driving cars are like airplanes

Yesterday, for the first time, an autonomous car a pedestrian.  It isn't clear that the car was at fault but we're almost certainly going to have an accident where the car was at fault at some point.  At this point autonomous cars haven't driven enough miles for us to know if they're currently safer or more dangerous than human drivers.  But I think they have the potential to be much safer in the long run for a combination of technical and institutional reasons.

Technically, cars can learn in the same way that humans can.  But while we humans are mostly limited to learning from the situations we encounter a fleet of cars can hope to learn as a unit.  Some accident occurs, engineers analyze it, and then no car in that fleet will make that particular mistake again.  It's reasonable to think about robo-cars trained on a body of experience far greater than a human could amass in a lifetime.

And I think that robotic car manufacturers have the right incentives to care about this too, for the same reason that airlines do.  People are just less inclined to trust other people guaranteeing their safety than their are their own abilities.  This is true when people choose to drive long distances rather than fly because they're afraid of some airplane disaster.  This is even true when they know that people like them are more likely to kill themselves driving than a professional pilot is to kill them flying.  It's sort of irrational but it's a fact.  And I'm pretty sure the same principle applies to autonomous cars.

For this reason airlines are scared of airplane crashes in a way most other industries aren't.  When a planes crashed into the World Trade Center on 9/11 lots of people became afraid to fly and started driving instead.  This caused 1600 extra car deaths in the year after 9/11, increasing the death toll of the attack by 50%.  Many airlines nearly went out of business.  So while any individual airline might be tempted to skimp on safety they're all terrified that their competitors will and then cause a crash that will seriously hurt everyone.  In many industries the regulated parties use their influence to make the regulator weaker but for the FAA the airlines do their best to make it stronger.

I think the same dynamic is liable to occur in the autonomous cars industry too.  People are just inclined to trust their own driving over a computer's unless there's very clear evidence that the computer is better.  As long as people can drive themselves on public roads autonomous car companies will be scared that an accident involving one of their competitor's cars will make people want to do just that.  So I expect that once the industry grows and stabilizes enough for a good regulatory body it will be pretty demanding.  And I expect that the companies that get involved will be fairly safety conscious about their autonomous cars even if they're lax about other things.

UPDATE:  Actually the crash that prompted me to write this actually looks pretty bad for Uber, but I still think the forces involved will make autonomous cars safer in the long run.

Monday, March 5, 2018

The Drake Equation again

I was walking in to work today and as I did I was listening to a nice podcast on the Drake Equation.  The Drake Equation is an estimate of the number of civilizations in the galaxy based on things like how many planets there are, how many develop life, etc.  I learned a lot in the Podcast but it reminded me of a post I'd been meaning to make about why I think the origin of life probably wasn't the hard part in creating us.  Also, I promise this post on the Drake Equation is more pleasant than the last one.

A graph:

Dates taken from Wikipedia's timeline of life and timeline of the future.

It was just a pretty short amount of time, geologically, from when the Earth cooled down enough for oceans to start forming until we have proof of the first life - just 120 million years.  And that's probably a conservative estimate.  But from there it took three quarters of a billion years for photosynthesis to arise.  Then one and a half billion until one bacteria swallowed another in such a way as to turn it into a mitochondria and then become a big complex eukaryotic cell.  Then another billion before we had real multicellular life. 

So just looking at the timelines involved it seems like the origin of life wasn't the hard part.  If you're interested Nick Lane has some excellent books about the biochemical difficulties of these steps and why life might have been the easy part but for the Drake Equation the important part is that becoming complex took a long time.

And it's also important that life only had so much time to become complex because in just another billion years the brightening Sun will heat up our planet enough to evaporate the oceans and then there's not much chance of intelligent life evolving.  And it's very lucky that photosynthesis showed up so early.  If the Earth's carbon dioxide atmosphere hadn't been broken down into oxygen then Earth might have had a runaway greenhouse effect by now.  And without oxygen in the atmosphere to form ozone we might have lost the hydrogen atoms we need for water to the Sun's solar wind.

Looking at that timeline makes me feel optimistic that the reason there don't seem to be any aliens in the galaxy is that evolving intelligent life is hard, rather than that intelligent life tends to meet a grisly end.

Tuesday, January 30, 2018

What are the effects of carbon dioxide in the atmosphere?

Apart from the obvious, or course.  Once, when our planet was young, the atmosphere was very high in carbon dioxide.  Then photosynthesis evolved and the cyanobacteria that spread across the oceans turned most of that carbon dioxide into oxygen about two and a half billion years ago.  Modern complex life, like ourselves, loves oxygen but for the creatures at the time this was a huge problem since oxygen was toxic to them and most of them died.  Plus the interruption of the greenhouse effect combined with the dimmer sun we had back then to turn Earth into a giant snowball for a bit.

But here we are billions of years later and carbon dioxide levels are increasing.  We should be worried about increasing temperatures but are there other reasons to worry?  For a very long time, compared to humanity, Earth's carbon dioxide levels were around 280 parts per million.  That's been going up recently and is now at 407 parts per million, a 45% increase.

If you are a photosynthesizing plant you might have complex feelings about this but if you're a mammal who really just wants to expel carbon dioxide from your lungs then there really isn't any upside.  We know that sufficiently high carbon dioxide concentrations will kill us but that takes  an atmosphere that's well above 10% carbon dioxide, 10,000 parts per million, very far from any levels we could plausibly reach by burning too much coal.  But some researchers have investigated the effect on people's cognitive abilities from going from 600 ppm to 1000 ppm and found easily measurable declines.  Now, poorly ventilated indoor spaces might easily get up to 2000 ppm so that's something to think about when designing office spaces.  But if a 400 ppm difference can result in obvious differences for people proofreading papers when briefly exposed can we be sure that there isn't some difference in human physiology that would stem from a 100 ppm difference across an entire childhood?  How about a 200 or 300 ppm difference?

This probably won't be a huge difference but it's not something that's been researched and not something you really could ethically research in humans.  But it is something that I think is underplayed in in our rhetoric about climate change.

Wednesday, January 24, 2018

Genetic engineering and chlorophyll

One of the interesting discussions in The Wizard and the Prophet was what the wizards are trying to get up to next in terms of trying to increase food production.  One idea goes to the fundamentals of photosynthesis.

The most important protein in photosynthesis is affectionately known as RuBisCO and makes up about half the protein in a leaf.  Photosynthesis seems to be pretty hard and so RuBisCO doesn't work as well as most other catalyst proteins.  It's supposed to grab the carbon in carbon dioxide from the air but frequently grabs plain oxygen instead.  I suppose it worked a lot better before the Great Oxygen Catastrophe.  Some plants have versions that are a bit more selective but they work more slowly.  Some are faster but they mess up which to grab more frequently.  Biologists hoped they could improve RuBisCO but it seems that evolution did about as good a job as could be done.

There are some plants, though, that do have method of photosynthesis that's often better than the run of the mill one.  They spend a little energy to concentrate carbon dioxide in cells where the RuBisCO is and so when RuBisCO grabs a random air molecule its more likely to be CO2 instead of O2, speeding up photosynthesis.  The extra energy means this isn't always a benefit, but it usually is.

Many plant species have developed this C4 carbon fixation process, as it's known, in nature.  Notably corn does it this way.  But researchers are hoping that you could develop a strain of rice that works that way too.  That is very ambitious.  Changing a single protein like RuBisCO is easy but this would involve growing whole new structures in the leaves to channel the CO2 and that doesn't involve just new proteins but new development paths.

That's very nifty but when I was reading the chapter my mind was going somewhere else.  The Great Oxygen Catastrophe was very good to use oxygen breathing creatures but it really sucked for plants.  Wouldn't the kind thing, for plants, be to let them live in a high CO2, low O2 environment?  And you could give the plants a high speed, low specificity version of RuBisCO that would work really well in that environment.

I'm mostly thinking of this in terms of growing plants in outer space but it could be applied in greenhouses too.  Enclosed environments also reduce the need for pesticides and herbicides though obviously the enclosures are expensive and have their own environmental impact.  And certainly there would be an energy cost in getting the oxygen the plants produce out of these buildings.

Oxygen free environments are dangerous.  But ones filled with CO2 less so.  Normally when you aren't getting any oxygen you feel perfectly fine as you get stupider and more lethargic until you die.  Here's a video from Smarter Every Day showing someone in a low pressure environment similar to a depressurized airplane and how he acts until given a breath mask.  When you hold your breath and feel like you're running out of air that sensation is caused by the buildup of CO2 rather than the lack of O2.  These always went together in our ancestral environment so there was no need for us to distinguish.  So at least in these greenhouses people with mask trouble could at least notice something wrong and leave.

I'm sure that some of you are thinking, "wait, how does this relate to all the CO2 we're pumping into the atmosphere?"   Well, plants will like the extra CO2 but the extra heat will make RuBisCO even less selective so for moderate warming it depends on the plant in question and for high global warming its generally bad.  Plus there are all those other very hard to predict changes in rainfall, etc, which would almost certainly be painful.  So lets not forget to work on better renewable energy too.

Tuesday, January 23, 2018

Book review: The Wizard and the Prophet

I just recently finished The Wizard and the Prophet by Charles C. Mann.  He'd previously written a book about the Columbian exchange I'd really liked, 1493, so I was ready to like this book too.

It concerns the dueling ideals of two men regarding man's relationship with the environment.  The prophet of the title, William Vogt, believed that the world has a finite carrying capacity that humans had to respect and that we had to limit ourselves to what the Earth could sustain.  The wizard, Norman Borlaug, worked tirelessly to increase the yields of the crops that man depends on and allowed large new generations of people to grow up without the famine that had plagued their parents.

Going through the book Mann seems to do an admirable job of looking at the lives of each; their successes and failures and the events that led them to be the people they were.  And the books makes a valiant effort to portray both fairly though, as you might expect, I end up sympathizing with the wizards more than the prophets.

I do worry, though, that it's the third position Mann introduces that is the correct one.  Vogt believes that mankind must constrain its reproduction and stop consuming as much.  Borlaug believes that mankind must learn to better use the environment to support ever more people.  Lynn Margulis believes that it would be unprecedented for mankind to do either of these so we should expect overpopulation and dieoff in the future.

My first reaction was "Wait, is this the same same Lynn Margulis who..." and yes it was.  She had argued that symbiosis rather than competition was the primary force in the evolution of our cells.  It was entirely true that mitochondria and chloroplasts were once independent bacteria who came to live inside eukaryotic cells.  It was untrue that the flagellum or the other orgenelles of the cell had also originated as symbiotes. 

We are lucky that affluence has reduced our desire to have many children.  Yet, there are those who desire many children even in affluence and there's no reason to think that this desire isn't at least partially heritable.  We may stem this, for a time, with violence but the will to violence fades .  We may race ahead of necessity in terms of our civilization's ability to provide sustenance.  Yet, the sun only puts out so much energy.  There are limits to the computation cycles that can be extracted from a unit of energy.  And expanding at the speed of light resources grow as the cube of time but demand grows exponentially and an exponent must always beet a polynomial in the end.

I'm closer to an average than a sum utilitarian so I can swallow this repugnant conclusion, even if I don't want to.

Tuesday, December 19, 2017

Charitable Giving in 2017

I don't know if I've mentioned it on this blog but a while ago I took the Giving What We Can pledge to donate 10% of my pre-tax income every year to efficient charities.

In general I'd recommend following Givewell's recommendations fairly closely.  In past years I've strayed beyond them a bit, in particular giving a bit extra to charities that provide micronutrients in poor countries on the theory that allowing kids to grow up healthier is investing in the future and maybe I ought to prioritize that over saving as many lives as I can right now.

On the other hand, Givewell's top charity is the Against Malaria Foundation and we, that is humanity in general, have been making huge strides against Malaria recently.   It isn't an impossible project to eliminate it in the wild.  I'm too young to have helped with the elimination of Smallpox but this would be another ancient enemy laid to rest.  The Against Malaria Foundation is a finite entity and might not be able to absorb all the money that everybody donating through Givewell can muster.  But if they can't Givewell will trickle the money down to other, nearly as important, charities that can use is so I gave the money to them to use as they see fit.

If I were emperor of the world with all resources at my command I would be careful to distribute my money through a variety of causes and means in case one was mistaken and independent analysis could show that.  But as just one person among many I feel comfortable contributing to the one organization I trust the most.

In previous years I've tended to double up my giving by year.  Donating in January of, say, 08 then again in December of 08 then January of 10 then December of 10.  I give as much as I intend, roughly, per year but I get to double up my charitable deduction while in off years I take the standard deduction on my income tax.  This year with the new tax bill passing I'm not confident on this working out for me so I figure I'll do the simple thing and just donate for the year I've saved in, before my bracket and standard deduction change.

Also, while I may think that giving to the most efficient charity I can find is the best use of my money overall I still feel bad when someone asks me for money on the streets of Cambridge and I don't give them any.  In theory I wouldn't mind them having a few dollars from my pocket but I also feel bad if I give money to the people who are willing to stand out in public all day asking for it while not giving any money to the the people who don't.  To assuage all my feelings of guilt I donate $5 to the Greater Boston Food bank whenever anybody asks for money from me on the street, which comes to $210 this year.

Sunday, December 10, 2017

Tax Rates and Growth

People trying to justify the recent Republican tax plan often talk about the importance of long run economic growth.  And you can see how, if that were true, it could be a really important argument.  The difference between 2% and 3% annual growth over a hundred years would be a factor of two and a half.  If that sort of change were really possible it would justify quite a bit.  Even if all that extra growth went to rich people then even at the new, lower, tax rates that would be much more tax money available for social programs.

Sadly there's no way cutting taxes could have such a large effect in the US.

The theory behind the cuts is that people become more productive when they've got more or better machines.  Machines cost money, so leaving businesses more money to buy machines will make them more productive.  More machines leads to more money leads to more machines in a virtuous cycle.  Except that in a developed economy it's often very hard to figure out how to usefully add more machines.

At work I mostly use a computer.  Giving me a second computer might increase how much I get done by a bit, but it wouldn't increase it very much.  Diminishing returns is a fact of life and finding ways to usefully spend money increasing productivity is hard.  Some people are working at companies where they have to make due with 20 year old computers and it's quite possible that they would work faster if they could upgrade.  But that's not typical in the US.  It does exist and there are cases where extra money can result in research that yields better computers for everyone.  This is why we try to slant the tax code to favor investment over consumption.  But again expecting lower taxes to increase growth by a large sustained amount is wrong.

There are cases, not in the modern US, where it can play out like that.  If you happen to live in a country that's pretty poor and where most businesses don't have the latest technology then you could quite plausibly have huge growth rates based on money to machine to money virtuous cycles.  That's what's happening in China right now.  It also happened in Japan 50 years ago.  If there's some other country that's figured out how build awesome machines you don't have yet then you might very well find yourself limited by how many of them you can buy - though you might also have other problems that are more pressing.

In this case what you really want to do, as a government interested in growth, is to increase the rate savings rate, how much people invest relative to how much they consume. 

One strategy for this, pursued by prewar Japan, is to just tax poor people and give out the money as business loans.  Even today richer people save more of their income and that was more true when you have a population of peasants without access to banks. 

The early 19th century US didn't have quite the bureaucratic sophistication of late 19th century Japan but managed to do something similar.  By introducing tariffs that raised the price of imported cloth and other goods they indirectly increased the profits of factory owners, allowing them to invest more by buying pirated copies of machines already in use in Britain.  It's much easier to apply taxes at single ports of entry on obvious things like ship arrivals than it is to do something like an income tax.

The early 20th century Soviet Union took this approach to new extremes.  Most new machinery in the early days was paid for by selling grain abroad.  The need to more efficiently expropriate grain was part of the reason for the drive to collectivize agriculture.  Big centralized farms are again much easier for the state to manage than lots of little spread out farms.  Sometimes there was mass starvation but the country industrialized rapidly.

You might have noticed that China's economy has been growing rapidly recently but there hasn't been a lot of mass starvation.  As far as I can tell the main difference was that they jump-started things with foreign investment  These days the trillions in domestic savings drown out the $100 billion or so in foreign capital but when the current boom was starting money from Taiwan, Japan, etc was crucial.  This seems like a far more human way of jump-starting growth than the other methods above.


Self driving cars are like airplanes

Yesterday, for the first time, an autonomous car a pedestrian .  It isn't clear that the car was at fault but we're almost certainl...