Saturday, December 19, 2015

Economic regulation and institution design

I've been having some thoughts about how the economy is regulated and the design of the institutions doing it that I've been meaning to put down in a blog post.  So here goes.

I haven't read Ben Bernanke's memoirs myself and maybe I should but I've been reading various economic bloggers reactions to them.  Here is an example.  One thing that stands out to many people is that during the financial crisis the Fed was so preoccupied with the banking system that they essentially forgot that they were also the agency in charge of steering the macro economy at large, trading off between inflation and unemployment and so forth.

"Nothing is as important as you think it is while you're thinking about it."

It's easy to see how this could happen.  In addition to trying to steer the macro-economy the Fed is in charge of bank regulation and that was generating an enormous amount of work in 2007 to 2008.  As the subprime crisis hit bank after bank went to the Fed for help.  Some were proactive but some, like the Lehman Brothers, only went to the Fed for help a few days before they collapsed.  But they all ended up screaming for attention at some point.

By contrast news from the macro-economy trickles in slowly.  If you follow the economic blogosphere you know the excitement when a new dollop of data is released about the economy.  When that happens we get a best guess about conditions a month in the past but also exciting updates about what the conditions really were for the months before that.  Inflation is complicated so it's hard to figure out what the various measures of inflation really are.  And data on employment isn't always passed around quickly.  That means that the Fed is always working with outdated information about the larger economy and is guessing as best they can.

Which causes problems when you're dealing with a crisis.  When Lehman et al were collapsing inflation was crashing too but the Fed's most recent information showed that it was higher than normal.  That's why the Fed took the unprecedented step of paying banks not to lend money when they were shoveling out cash trying to stop the financial crisis.

That's a problem.  If there was some macro committee in charge of inflation and and a bank committee in charge of the banks then the bank committee could have happily gone into panic mode while the macro committee could have looked at all the signs that a larger economic slowdown was causing the financial crisis just as much as vice versa and taken appropriate steps.  The signs were there in the TIPS spread and other places but you can't expect a committee with a thousand banks screaming at them to go out and proactively look for economic data.

Another problem that separate committees would solve would be the question of who gets a seat at the Fed board.  The Fed has a number of brilliant economists like Bernanke but also a large number of people who are familiar with running or regulating banks but are generally ignorant of macro-economic theory.  During the crisis I was sometimes pulling my hair out at some of the things the president of the Texas Fed was saying about he thought that the economy was probably going to be ok 'cause his business buddies said they were doing ok.

There was some hope during the great recession that Obama would nominate some Doves to the Fed committee and balance it out but sadly that was not to be.  After a long delay Obama finally nominated some candidates who I'm sure were very progressive in their ideas about bank regulation but who were very conservative in their views of monetary stimulus.

It's not surprising that people who have spent their lives thinking about what is prudent in terms of institutions that can't print money should develop firm ideas that don't necessarily apply to institutions that can print money.  But that's something we could resolve by separating the two functions.

The Theory of Moral Sentiments

That's all about the macro-economy.  What about bank regulation?  I'm very unconvinced that Dodd-Frank or any of the other changes since the financial crisis will actually help in the long run.  Congress routinely delegates legislative power to bureaucrats who can make rules for the legislation of the industries they're charge with.  We also have the problem that the number of pages of law regulating the financial industry grows but the number of people charge with enforcing those laws does not.  And so the enforcement grows ever more arbitrary.

In the short term this isn't a problem.  All the bureaucrats in charge of enforcing the rules remember the financial crisis.  It looms large in memory and for the next while we shouldn't worry about lax enforcement.  But the traders and executives on Wall Street also remember the crisis where many of them lost everything.  Those memories will last for a number of years and while they come quickly to mind I wouldn't be surprised if we barely needed any regulation at all in practice and that fear of those frost giants who in 2008 descended from the north and tore down the towers of the Lehman Brothers wouldn't be enough to keep bankers mostly in line.

But as time passes memory fades and the children of summer who have never known great hardship come to take more and more responsibility.  The lessons of the financial crisis will fade and a new generation will come who want to take greater risks.

The problem is that at the same time the memories of the regulators will fade too.  Young bureaucrats who weren't there in 2007 will rise up.  They will want to do the right thing but like most psychologically normal humans they will want to get along with the people they interact with every day.  And many of those people will be the new banker chafing under the restrictions placed on them.  The laws run into their hundreds of pages of vague categories and it will be very easy for the sympathetic ear to say "Yes, I'm sure that extra risk won't cause any problems."

That's how we got into the original crisis in the first place after all.  The Basel Rules admit many categories of financial instrument based on how risky the regulators think they are.  With the tranches of subprime mortgages the regulators agreed that they were probably quite safe and let banks leverage themselves very heavily on them.  The savings and loans crisis of the late 1980s had grown dim in the minds of both the bankers and the regulators so stuff like that didn't seem very dangerous.  But it was.

A good response to the crisis would have been to recognize that deciding which investments are risky and which are safe is too hard a problem to expect people to solve reliably.  We could just expect or banks to stay below some fixed amount of leverage and leave it at that.  But instead of created a large number of very complicated rules that will probably be interpreted strictly for a while but more and more loosely as caution fades.

Then this will happen all over again.

Thursday, December 3, 2015

(Late) November Links

I should have put this up a few days ago but I was somewhat distracted starting my new job at RightHand Robotics.  There are some pretty cool videos on our front page.  But on to a curated list of nifty things I found on the internet in the last month!

Nature has a good list of some interesting unsolved mysteries in physics and cosmology.

There are a lot of nifty things that can only be made in microgravity like foamed metal and antibiotic crystals.  Now we can add metal glasses to this as well.

A lot of the time we think of conservatives as being in favor of "original interpretations" of the Constitution and liberals as being more supportive of the "living constitution" approach.  There are good reasons for that but it's worth remembering that many of the things that the Black Lives Matter protesters and others criticize about how our criminal justice system handles police immunity were "judge created law" as conservatives usually put it.  The recent ruling saying that policemen can't be sued for using deadly force against fleeing suspects is just another example.

There's been a lot of ink spilled on the problem of replicating experiments in psychology recently.  Here's a comic that basically shows how you get the problem.  Here's a nice article on how you can find it via analyzing papers without having to do a study yourself.  And here's on possible solution.

There was a kerfuffle at the MFA recently with their Kimono exhibit which let museum patrons try on kimonos.  A diverse group of people protested saying that this was cultural appropriation and the counter-protest of a group of Japanese and Japanese-Americans wasn't able to prevent the museum from closing the exhibit.  And of course back in Japan people mostly interpreted the protesters as just being anti-Japanese.

Some people are thinking of mining undersea vents.  I think that article did a pretty great job of covering the pros and cons.

The New Yorker had a pretty excellent piece on Nick Bostrom and some of his ideas.  I've been following him since 2001 or so and I was happy to see it.

And speaking of the New Yorker they also got Randall Monroe to do a piece on the 100th anniversary of Einstein's theory of relativity.

On average about 56 million people die each year so roughly 4.6 million died in the last month.  Wikipedia has a list on the few hundred who are the most famous.  One particular one, Joseph Engelberger, was "the father of robotics" which struck a bit close to home (though he actually died Dec 1st).  Every one of those millions of deaths is a tragedy and it's worth remembering that when we consider the various people killed in terrorist attacks this month.  The 9/11 attacks killed 3,000 people directly.  The extra road deaths they indirectly caused through people not flying as much, through fear of terrorism or TSA hassle, now stand at about 7,000.  But in the end both of these numbers are tiny compared to the vast ocean of suffering that exists in the world.

Saturday, November 28, 2015

Do we have to worry about contaminating Mars?

Whenever we send a probe to Mars we spend a lot of effort scrubbing it to make sure that there aren't any terrestrial microbes hitching a ride to the red planet.  There's a lot of sense in doing that.  Scientists are curious as to whether Mars has any native life.  If we spread earthly bugs to Mars then it might be hard to tell if whatever we find had its origins on Mars or Earth.  But I wonder if the cat isn't already thoroughly out of the bag.

Way back in '84 some scientists found a meteorite that they realized had initially come from Mars.  Some larger rock had hit Mars 17 million years ago and this future meteorite had been blasted out of the crater so hard it actually left Mars altogether.   For a very long time it orbited the sun until eventually, 11,000 years ago, it managed to land on Earth.

All well and good but you'd think that any rock being blasted off a planet would be pretty thoroughly sterilized in the process.  Some years after the meteorite was discovered, in 1984, some scientists gave it a hard look and made a pretty amazing discovery.  There were structures inside the rock that looked a lot like fossils.  That isn't conclusive evidence that there was once life on Mars since people have found non-biological ways that those structures could have formed though it is suggestive.  What it does prove, however, is that neither the shocks to the rock nor the heating it endured were enough to destroy them.  In fact, small things tend to deal with acceleration very well and bacteria are very small.  And no matter how much the outside of a meteor might warm up when it enters the atmosphere the inside tends to remain pretty cool as this one did.

Could some spore remain viable for the 17 million years it took for this meteor to get from Mars to Earth?  I have no idea but there are probably rocks that didn't take that long.  Earth has been around for 4.5 billion years and life got going pretty fast, maybe 4 billion years ago.  So that's an awful lot of chances for some ejecta to leave Earth and make the trip in a lot less than 17 million years.  The speed with which life evolved after Earth got oceans is sort of evidence that Mars should have developed life too when it had oceans but that's far from certain.

Of course Earth's gravity well is a lot steeper than Mars's is at 10 km/s to 5 km/s.  So an impact that would hurl a terestrial rock into space would be much rougher than one that would do the same on Mars.  Maybe life can make the trip from Mars to Earth but not vice versa?  That seems improbable to me but I can't rule it out.

And on the other hand again it seems very odd to me that Earth microbes could be transported to Mars and out compete any native Martian microbes.  In a warm sea, sure, the evolution of Eukaryotes was improbable and I could easily see them beating up Martian bacteria.  But the sort of extremophyle bacteria that could live under Martian conditions are much simpler and haven't had the opportunity to gradually evolve along with Martian conditions.  It might be that Mars is actually totally dead but life could live there if seeding by ejecta really is impossible.

This whole post is totally speculative of course and I don't really know that much about the current rationale behind NASA's policies.  Maybe they were put in place in the 60s when we didn't know so much about the solar system and have persisted through inertia.  Maybe they're carefully and continuously evaluated.  I've tried to find places to ask these questions but without much luck.  Maybe, if I'm lucky, someone will read this and enlighten me as to what I might be missing.

Saturday, October 31, 2015

October Links

Here's some speculation that Tesla's new Model X is mostly about developing an automated electric taxi.

James Lind pioneered medical trials in figuring out that limes can prevent scurvy.  But by 1911 the measures used to fight scurvy had become ineffective without anybody realizing it because they changed how the lime juice was prepared without checking to see if it was still effective.  Nobody knew what vitamins were and nobody was going to give someone scurvy and then see if the new preparation cured it.

But in more optimistic news, this month the United Launch Alliance completed 100 satellite launches in a row with no failures.  Considering that this is rocket science and that somewhat more than one out of every 20 satellite launches fails that's really impressive.  So happy 100!

In other space news that doesn't actually take place in space The Martian came out and I loved it.  It captured most of what I loved about the book, was really pretty, and was remarkably accurate to what a real Mars mission might be like.  Here's some fun (for people like me) nitpicking at the book and here's a better orbit for getting Watney home but which nobody would have been able to figure out when the novel was published.  Which just goes to show that doing something like sending people to Mars is the effort of a civilization and that nobody is smart enough or knows enough to get everything right.  You really ought to see the movie or read the book.

We like to make fun of the Victorians for believing they could determine someone's personality based on the shape of their skull.  But at the same time there's been a lot of research since the late 90s showing that most people tend to reflexively make judgments about other people's personalities just based on their faces.  And there is some evidence that at least some of this is at least correlates with real effects.  Especially face width and testosterone.

There were some political debates.  I can't say I'm really excited about any of the countries.  I know a lot of people are excited about Bernie Sanders.  For myself, I can't really take someone seriously when they keep calling Denmark socialist given that Denmark is pretty much a neoliberal poster child with no minimum wage, privatized fire departments, and ranks 4th in the world in terms of ease of doing business.  And here's the Danish PM explaining why his country isn't socialist but be warned, it's a long video.

A while ago I blogged that I thought there'd have to be some sort of drone registration at some point.  Clearly someone at the Department of Transportation was listening because they'll be attempting to register drones now.  And there's more details on the matter here.  I don't know how they're hoping to get the registration of drones that, e.g., buzz people but it looks like they're thinking about it.

A few years ago I mostly thought of mutations as mostly being about germ line mutations or cancer.  Germ line mutations are particularly important because without that there's no way that evolution can give rise to new species and for a while there was a big war in biology between the Darwinians and the Mendelians.  A recent book I read about Mitochondira, Power, Sex, and Suicide, contended that accumulating mitochondrial mutations were one of the main mechanisms of aging which shifted my view.  Then I learned that the immune system mostly learns about new pathogens by mutations in immune cells.  And now it looks like there's a certain amount of genetic re-writing going on in your brain as well.  When people talk about the heritablility of intelligence they talk about the part that the part that is genetic, the part that comes from the environment you share with your family, and the non-shared environment.  It looks like a chunk of the non-shared environment might be what non-heritable mutations you happened to get when your brain was developing.

23andme is a company that lets you get your genome mostly-sequenced for $200 and used to tell you all sorts of interesting things about the traits you carry.  I bought there service and was really happy with it.  They'd started out being regulated as a genetics laboratory under the CMS.  But the FDA thought that doing sequencing and explaining what those sequences mean under the same roof made 23andme a medical device rather than just a lab and essentially closed the analysis part down until the FDA did a review.  Thankfully you can still find you genes on 23andme and then put them into SNPedia to find out what they mean.  Even more thankfully the FDA has completed some of its review after 2 years and now you can find out some of what you could if you had signed up before 2013.  Or you could move to Canada or the UK where regulators have given 23andme full approval since 2014.

You might remember last month that a company jacked up the price of the (off patent) drug Daraprim from $13.50 to $750 a tablet.  Some good news is that someone is now offering the drug for $1.  They can get away with that because they're a compounding pharmacy and don't have to sepend the 3 years and $100 million that you normally would to have the FDA let you start manufacture of a new drug.  That's probably illegal since compounding pharmacies aren't supposed to make big batches but hopefully the FDA won't enforce the law here?  I understand the desire to standardize drug production practices because of what happened with lemon juice near the top of this post but I wonder if we haven't gone overboard here.

Here's a Youtube video of Vecna's "Robot Race" that I was in this last spring.  You can see me at some points.

Saturday, October 17, 2015

Ethics at a distance

I recently read a blog post  talking about the Copenhagen Interpretation of Ethics:
The Copenhagen Interpretation of Ethics says that when you observe or interact with a problem in any way, you can be blamed for it. At the very least, you are to blame for not doing more. Even if you don’t make the problem worse, even if you make it slightly better, the ethical burden of the problem falls on you as soon as you observe it. In particular, if you interact with a problem and benefit from it, you are a complete monster. I don’t subscribe to this school of thought, but it seems pretty popular.
Jai then goes on to list a bunch of examples which it would probably be worth your while to read through but that's the important part there.  It's a thing I had noticed before in a few places.  Here's a short passage from Debt: The First 5000 Years:

In the early decades of the twentieth century, the French philosopher Lucien Levy-Bruhl, in an attempt to prove that "natives" operated with an entirely different form of logic, compiled a list of similar stories: for instance, of a man saved from drowning who proceeded to ask his rescuer to give him some nice clothes to wear, or another who, on being nursed back to health after having been savaged by a tiger, demanded a knife. One French missionary working in Central Africa insisted that such things happened to him on a regular basis.
That sounds really weird to modern ears but there's some important logic to it.  You or I interact with complete strangers every day.  If there isn't any state that enforces laws on everybody within its boundaries then meeting with strangers is a dangerous business.  So everybody you interact with is going to be a neighbor or relative and generally people share more than people who live in states do, especially if they're hunter gatherers rather than farmers.  And if saving someone's life makes you no longer a stranger and the person is much wealthier than you then it makes sense to want them to give you their knife.

And of course that's no serious issue.  The rescuer was still free to refuse and to eventually go home on their own.  And the rescuee is still alive even if they're being rejected.  In the long history of cultural conflicts brought about by European colonialism this is barely worth mentioning in terms of impact but I think it illustrates the issue rather well.

And of course there are some much bigger issues in the world where our desire to not interact with evil can cause trouble.  The first example that springs to mind for me is the anti-sweatshop movement.  As Krugman pointed out in his famous article the conditions of people who work in sweatshops are almost invariably worse before they get their sweatshop jobs.  It's perfectly natural to feel worse about someone slaving away for something you use then about that same person having an even worse time with no relation to you.  But if we want to make the world a better place our reaction to the knowledge that the people who made our clothes suffered shouldn't be to cut our connection to them.

And of course I can relate this to my hobby horse of immigration too.  People often cite the cost of immigration in terms of government support or letting in people who might vote foolishly.  But as Bryan Caplan argues:

If immigrants hurt German workers, Merkel can charge immigrants higher taxes or admission fees, and use the revenue to compensate the losers. If immigrants burden German taxpayers, Merkel can make immigrants ineligible for benefits. If immigrants hurt German culture, Merkel can impose tests of German fluency and cultural literacy. If immigrants hurt German liberty, Merkel can refuse to give them the right to vote. Whatever your complaint happens to be, immigration restrictions are a needlessly draconian remedy.
This is true but of course we all quail in horror at the idea of keeping people as second class citizens in our countries.  It might be objectively less harsh but that's not how it feels to us because the people we would be denying things to would now be close to us and clearly our problem whereas if we just kept them out of the country they'd be far away and the problem of other nations just as much as ours.

And of course those two examples are things aligned with my own politics.  I'm sure there must be ways in which I fail prey to this that my biases prevent me from seeing.  All I can do is watch myself for this and hope to avoid it in the future.

Thursday, October 1, 2015

September Links

An alternate possibility is to locate a colony on the surface of another planet. Most recently, the case for colonizing the surface of Mars has been argued by Zubrin [1996]. However, at least compared to the benign environment of Earth, the surface of Mars has several disadvantages. It has a low atmospheric pressure, low temperatures, and high exposure to cosmic radiation, and, while it is not a zero-gravity environment, it is not yet known whether the roughly one-third Earth-normal gravity of Mars is sufficient to avoid the bone decalcification and muscle tone loss experienced by astronauts in microgravity.

So let's colonize Venus (pdf)

Here's a blog on art at Burning Man.  Here's some more. Sort of makes me want to go.

There was a recent quiz on Vox to help people figure out how much their political beliefs influence their factual beliefs.  I'm reminded of this.

This huge photo of Pluto is gorgeous.  This has a lot of good pictures of mountains that seem huge compared to the former planets curvature.  And here are some more cool photos with nifty explanations.

In addition to New Horizons unburdening itself of all the photos it took there was also a big discovery of liquid water on Mars.  There'd been a lot of evidence pointing that way previously so I guess I wasn't too excited about that.

All probes that we send to Mars are sterilized to make sure we don't spread Earth life there but I wonder if there's any point to that.  We've found that meteors that originated on Mars can land on Earth with structures showing they haven't been sterilized.  Now, ok, the escape velocity of Earth is 11 km/s and the value for Mars is just 5 km/s so it's probably easier for rocks to be ejected from Mars than from Earth.  But Earth has had life for a long time and I think that if Earth life could live on Mars it probably would have gotten there already.  Or maybe there's something I'm missing?

Japan passed a law allowing the deployment of military forces oversees.  It seems like that would run afoul of the constitution to me but I'm no expert.

There was a pretty good article in 538 earlier this month about how the FDA could change how it approves drugs to allow less scrutiny for drugs treating very deadly diseases but more scrutiny for drugs treating less serious things.  Seems like a good idea to me.  In other drug related news someone jacked up the price of a generic drug from $15 to $750 a tablet.  Which is a terrible thing done by a terrible person.  But it's bad that we've created a system where terrible people can do terrible things.  Companies in India are selling it for about 10 cents now and if we don't trust India then in theory we could import it from Europe for it's previous, reasonable price.  But that would be illegal.  Here's a much longer (but worthwhile) discussion of generic drugs.

In Oklahoma it looks a lot like an innocent man is going to be executed soon.  He was going to be killed today but the governor delayed things due to a procedural issues.

On a sort of happier note I want to say how happy I am about Germany welcoming Syrian refugees.

Monday, August 31, 2015

August Links

Criminal justice reform is a big issue for me so I'm glad someone has gone to the trouble of reading all the things the various presidential hopefuls have said about it and giving the digested version here.   And relatedly, a group associated with Black Lives Matter has released some generally good and necessary proposals for police reform.  Here's a take on them I'd endorse.  But here's a post on how a citizen review board is harder than it seems I'd also endorse, for reasons I went into here and here.

If we want to be sending missions to Mars or thinking about colonizing the Moon we really have to learn how humans respond over the long run to gravity that isn't Earth normal or free fall but we haven't been researching this even though we should.

Remember that post I did on electric rockets? Someone on the internet was nice enough to give a lot of details about the various sorts that are being built now.

I'm sure we've all noticed that humans are getting fatter.  The weird thing is that other animals that live around humans are getting fatter too.  Even lab animals that ought to be fed the same way they always were.  It's really weird.

Is the FDA too conservative or too aggressive?  A bit of both.

When I think about the potential end of Moore's Law it's comforting to know that there are other laws like Koomey's that have been going on for longer.  And also that the universe gives firm theoretical limits to how advanced computers can get and that we still have a factor of 107 to go before we reach them.

Tuesday, July 28, 2015

July Links

You might have heard of a company named vGo.  They make telepresence robots and have had some success selling them, though they haven't grown much recently.  Well, we (Vecna) bought them.

So, the Tories have announced some new economic policies including replacing assistance to the poor with a higher minimum wage.  That's sort of odd for a conservative government.  The general consensus among economists is that raising the minimum wage within reasonable bounds tends to help poor people overall at the expense of a modest increase in unemployment.  Policies with drawbacks are always uncomfortable and some on the left have argued that there isn't actually any disemployment effect.  But some on the right have argued that a loss of jobs is actually a good thing because it disproportionately affects foreigners.  That view was not uncommon when minimum wage laws were first being proposed but I can only find one person baldly advocating that view these days.  But Britain's proposed minimum wage law looks different than the US's and Britain doesn't have any easy way to prevent European immigration while remaining inside the EU so I'm somewhat suspicious that this change is in fact due to worries about immigration.

In happier news the march of Moore's law continues to 7nm.  Now with Germanium!  But sadly it does appear to be slowing down.  Intel is going to be going an extra year without a node shrink.

I'm sure we all saw stuff from the Pluto flyby but here's a list of all the other probes out there and still operational.  Some might do stuff just as exciting!

Lets say that you have some magical communication device that lets you talk to someone somewhere else in the universe and you don't know where.  Because all the laws of physics are the same under translation and rotation there isn't any experiment you can do to figure out where the entity you're talking to is if you can't find a common landmark.  That's because all the laws of physics are symmetrical under translation and rotation.  But, assuming you're both made out of matter rather than antimatter, you can find out whether the alien is left handed.

Some interesting data on welfare states around the world.  The US's 8% of GDP spent on public provision of healthcare is more than Britain's 7.7% despite being spent on a much smaller proportion of the population (page 4).  However we do a good job of using the government to transfer money to the poor rather than the rich, just look at Greece (page 5).  But really there's interesting stuff on every page.

Saturday, July 18, 2015

Democracy is a complicated business

In my recent post on Greece I was a bit cynical about the idea of public opinion but evidently I wasn't cynical enough.  But maybe cynical is the wrong word because democracy is hard.  How on earth are the Greek voters supposed to understand all the issues surrounding the acceptance of the EU deal?  I certainly don't.  I suspect that nobody actually has a good idea about it.

So Greeks just saw they that in retrospect their lives hadn't gone very well under the previous administration and so voted in someone else.  And if you're facing potential leaders whose performance you can't judge in detail then replacing them when things go badly is the only sure way to make sure they'll be interested in things going well for you.  That might not be fair to politicians who preside over bad times through circumstances outside their control but that's a relatively small price to pay.

Of course there are a good number of issues where it's easy for voters to tell what's going on.  Gay marriage for instance.  Shortly after a majority of Americans started to support it we saw many politicians quickly throw in their support for it too.  And don't judge them harshly!  Support for gay marriage correlates strongly with education and you'd expect politicians with advanced degrees to have mostly been in support of it before 2012 in the privacy of their heads.  I think I'd rather live in a country where more educated people hid their values and got elected and did an OK job on the complicated parts than a country that had more honest but less competent politicians.

Of course the danger of dishonest politicians is that they'll find some sneaky way to help their friends at the expense of electorate as a whole.  And that's certainly a valid fear as you can see from all the corn subsidies and taxi licencing regimes we've got.  People place too much emphasis on money and too little on public choice but they come to the same thing in the end.  But I think I'll still take the intelligent but slippery over the well intentioned but ignorant.  Look at the relative harm of prohibition versus all those corn subsidies.

But even smart and dedicated politicians don't know enough on their own to govern effectively.  Establishing a good upwards flow of information was a large part of why many kings established parliaments that would later bind them.  I wrote an earlier post a while back about why the problem of politicians mostly getting their information from self-interested sources.  I was talking about SOPA then but in the case of negotiations such as the one Greece was in with the rest of the EU or the one that the US is in creating the TPP the problem gets worse.

If you hope to do well in bargaining it's absolutely essential that you conceal things from the person you're bargaining with.  If I'm in negotiations with someone and they know the minimum price I'm willing to accept they can just offer that price.  Now, there are a lot of human factors pushing non-sociopaths towards being much nicer than that but the ceremony of modern diplomacy seems to insulate negotiators from those social pressures.  Maybe it's designed to do that.

But of course the need for secrecy opposes the need for open debate about what sort of deal we want.  As a negotiator you want input from people who will be effected but you don't want the terms you're considering to be leaked.  Ordinary citizens have concerns but there's no way to poll them without the issues you're considering being leaked.  Large corporations, however, have officers who are few enough in number that you can probably keep your intentions secret from the other negotiation teams even if you consult with the officers extensively.

I have no idea how to fix this problem.  Maybe just do trade policy unilaterally instead of via negotiation?  Most people think of tariffs as good if they're your own country's tariffs but expert opinion disagrees and unilaterally lowering tariffs doesn't require secret negotiations.  But of course given people's beliefs about tariffs that's hardly democratic and politicians have to worry about prospective beliefs about what will make them better off as well as their retrospective beliefs about whether their lives have gotten better.  And only some negotiations can be solved unilaterally anyways so really I've got little in terms of useful suggestions here.  I suppose we have to rely on the prospect of public outrage after negotiations are over to keep special interests in check.  If Disney loads up the TPP with juicy goodies for themselves and it gets voted down by the Senate then they'd have been better off having more modest aims.

There is one strategic advantage democracies have in negotiations.  I mentioned earlier that if your negotiating and somebody offers you a deal that's just barely better than nothing (or your BATNA in negotiations theory parlance) then the "rational" thing to do is to take it.  I put "rational" in quotes because if you're the sort of person to walk away from an inequitable deal and your opposite number knows this then maybe they won't be tempted to offer you an inequitable deal.  This is dangerous since it relies on everybody have a shared honest assessment of what an equitable deal would be but it can be very effective.  The structures of diplomacy can make it hard for negotiation teams to act this way.  Voters are pretty good at it, though.

And of course that's what the Greek referendum was about.  Except that public opinion polls show that the public of both Greece and the rest of the Eurozone are pretty fed up right now.  And the EU's BATNA was a lot better than the Greek's.  And given public approval of the deal Syriza was forced to take it looks like the Greek public understood all this, voted "no" to give the negotiators ammunition, and understood that they'd got the best deal they were going to.  Or they think the deal is better for them than it is but the issue is so complex that nobody really knows how good it is.

Thursday, July 9, 2015

Dynasties and their constraints

Thinking Out Aloud is a blog I've subscribed to for a while and they recently summed up the whole reason I read them in an utterly excellent post.  Seriously, go read it!

Now that you're finished I'd only add that perhaps a lower number of officials per capita in places like China or Russia can actually encourage vesting those officials with more arbitrary power.  If you're going to force your officials to operate within the narrow confines of written law it seems like you're going to need more review and with few officials that becomes harder to afford.

Tuesday, July 7, 2015

My somewhat complicated thought about Greece

So Greece voted "no" last Sunday.  It's not really clear what this means other than that Greece will not be agreeing to the terms of its creditors.  Terms' whose deadline had actually expire before the vote was held.

It's easy to understand the Greek position.  Syriza didn't do anything, as far as I can tell, to cause the huge debt that Greece had racked up - that was all the fault of previous governments.  There's also the issue of aggregate demand.  When the government stops demanding as many goods and services then a smaller number of goods and services get made, at least in the short term.  In other works the Greek economy would shrink.  And of course a shrinking economy would make it even harder for the Greeks to repay their debts.  If Greece had its own currency then they could offset this as most countries outside the Eurozone which have engaged in austerity have done but sadly Greece is not in that position.

Way back when the Euro was first proposed a lot of economists including Milton Friedman and Paul Krugman were saying that it was a bad idea and would just lead to trouble of the sort we're seeing now.  I entirely agree and I was sort of expecting a number of the Eurozone countries to leave early in the financial crisis (shows what I know).  There's a part of me that thinks that it would be best if Greece were to just "hoist the black flag," leave the Euro, and hope the whole thing falls apart.  But of course while that might be a good idea in the sufficiently long run it would probably cause all sorts of problems in the present.  And long run benefits become uncertain by their very nature.

So I think that the best thing would be if Greece were bailed out and stayed within the Euro but that seems politically impossible.  Greece isn't exactly rich but it's certainly wealthier than many of the countries in the EU that would be contributing to supporting Greece which seems unfair and which I couldn't really expect or desire those countries to support.  

You could ask that only the those EU countries that are richer than Greece to help Greece out but the problem is that those richer countries are democracies.  I've got a good deal of faith in democracy but that's mostly about people's retrospective rather than prospective voting.  I'd like to say that any Greek bailout is one of those complex questions where public opinion doesn't really exist per se but it's been covered a lot in the news recently so it looks like the the citizens of the wealthier European countries have formed definite opinions and it doesn't look like they'll continence a more generous offer even if it would ultimately be to their benefit in the long run.

Monday, July 6, 2015

Robot Fighting

I work with robots professionally and a lot of what we do at Vecna is trying to make robots harmless.   Noticing obstacles and avoiding them.  Not running into people and not even letting them think we might be about to run into them.  That sort of thing.

But other people have robots that behave differently and there's been a bit of activity recently.  It's been sort of cool.  BattleBots, a TV show about robots fighting in an arena, has recently come onto the air and you can see all the fights here.  The actual shows have a bit more team background which is sort of filler but also makes the fights a bit more dramatic.

However, the drama on BattleBots is nothing compared to the gauntlet that was thrown down recently.  Megabots is a group that's sort of trying to start something like BattleBots but instead of 250 pound remote controlled hunks of metal with buzz saws they're imagining 9000 pound piloted paintball wielding robots.  To drum up publicity they recently challenged a Suidobashi Heavy Industry's giant piloted robot Kuratas to a duel.  Here's the challenge and here's the acceptance.  Ok, it's PR.  But it's still super exciting!

Wednesday, July 1, 2015

June Links

I guess this is a pretty good description of why I signed the giving what we can pledge
The active ingredient in effective altruism was always supposed to be making it harder to trick yourself into feeling like you’re helping unless you actually are. - this was part of how I interpreted Eliezer’s post The Unit Of Caring. Money is something that definitely helps a quantifiable amount, and giving away money isn’t much fun, so by limiting your contributions to money you have sort of a commitment mechanism so that you know you’re actually helping instead of just signaling helping.
A very good data visualization of the cost of World War II.

There was this big competition for robots trying to complete an obstacle course and do various tasks.  But what people were really interested in was all the robots falling down trying to complete it.

Remember how I was all excited about HP using memristors for their big new project?  Well it turns out they won't be using them after all.  I'm glad the systems level work is being done but clearly this technology isn't as ready as I thought it was.

Boston has a pretty cool mass transit system by at least two metrics.

Selenium Boondocks goes over some of their best posts from their first 10 years of blogging.

Neural networks have been making a bith of a resurgence these last few years.  In terms of processing visual data Google has done some work on showing what they're looking for.  Some of those images are really trippy.

Remember Dune in Calvin and Hobbes?  Here's Game of Thrones mashed up with Peanuts.

Here's an interview with a former policeman in Baltimore on what he thinks the problems in the force are.  This sort of makes me think the move, long ago, to put police in cars to keep them isolated from their communities was a bad idea.  I won't say that enforcing laws on communities that think they're unjust (part of the original motivation) is always a bad idea btu I think the cost was badly underestimated.

People have been doing research on certificate of needs that are required to build new hospitals and it doesn't look good for the poor or really anybody else.  Back in the 1970s there was a common idea that "dog eat dog" competition between companies made capitalism less efficient than socialism and that we needed to prevent competition in order to lower healthcare prices.  This sounds really weird nowadays for good reason but most of the laws designed to lower healthcare costs by preventing competition between hospitals are still on the books.

Sunday, June 14, 2015

Nanotube memory

Followers of this blog may remember some previous posts I'd made about new non-volatile memory that looked like it could also fulfill the same role that RAM does now.  That is, it's reasonably dense and fast and so could be used as the working memory of your computer but also doesn't lose the information it holds when you turn off the power.

Well, yet another type of memory with these properties has been in the news recently.  The stuff is called NRAM after "nanotube."  The nanotubes in the name are the same carbon nanotubes that people talk about making a space elevator with if they can be made long enough and in sufficient bulk.   People have been trying to make transistors out of nanotubes for a while and they work but there's a big problem with manufacturing them at scale.  You make a big silicon chip with conventional techniques with a bunch of pads on it which you want the nanotubes to stick to.  You wash it with a solution containing the tubes and some bonding agent but you'll be lucky to get a tube at 90% of the places you want them.  That's enough to do experiments but it's still way too high to build any sort of computer out of.  When I first read the EE Times article on this I thought that NRAM would work in a similar way and that they might have manufacturing difficulties.  But then a new article with a bunch of presentation slides came out at Anandtech showing that each connection is made up of several nanotubes so you don't have to have every junction have the same configuration and some variation shouldn't prevent it from functioning.

Then I managed to find a link to an actual PowerPoint presentation form a Real World Tech forum thread.  It has a lot of details, including the actual current defect rate of .00003 which ought to be fine.

So how does this stack up against the other potential non-volatile memories people have been working on?  Well it does seem to be pretty tough.  There are actual molecules being shifted into different configurations so it's resistant to electrical damage which is why NASA was interested enough to fly some up to test it in space.  Cosmic rays flipping bits is a big problem for computers in space and even if NRAM doesn't have anything else that might be a niche for it.

The write endurance also seems to be pretty good, just like with RRAM.  With at least 10e11 writes you could be writing across typically sized RAM card at typical max speeds and it would take you a millennium to exhaust the writes.  Even if you write to the smallest area that won't be absorbed by the cache system on a modern CPU you've got a year of writing before you burn a hole there.  For typical usage I'd guess it would last something like 20 years which ought to be good enough.

Which of this and MRAM and RRAM will win out if any does?  I've got no idea but I'm finding it interesting.

Insurance and Driverless Cars

There was an article in IEEE Spectrum recently about insurance and driverless cars.  It was basically talking about how you'd expect the manufacturer of the driverless control to take over the job of insuring the cars when they operate in driverless mode because they're big enough to and they have more information than anyone else.  The price of this would probably be part of the cars price.  It occurs to me that if insurance for a car's automated and manual modes become separated and if the automated insurance is bundled then this will be a force pushing for 100% automated roads if driverless cars take off.

Now, clearly this would be a major hit for the insurance industry and all those people whose livelihood depends on insuring vehicles are going to be putting pressure on politicians to stop these forces from affecting them somehow.  I'd expect a major push to require all cars to have manual driving insurance whether the car has a manual mode or not.  But after that I'd expect insurance companies to offer cheaper insurance for those cars and there to be a race to the bottom that makes the whole issue nearly moot.  Or quite possible there's some side of this that I'm not seeing.

It's Alive!

Remember Philae, that robotic probe that the Rosetta mission dropped onto that comet?  It turns out that harpooning comets is tricky as this rather cute xkcd comit sequence explained and Philae bounced a few times after landing and came to rest in a shadowed cleft where it couldn't power itself (pictures of journey and cleft here).  Scientists had hoped that as the comet got closer to the sun the increased light would be enough for Philae to power itself up and resume communications.  Luckily that's exactly what happened.  It looks like Philae is working well enough to give us all the measurements we wanted as it passed near to the sun.

Sunday, June 7, 2015

Seveneves and the Roche limit

For an author it's important to get things that the reader might find hard to swallow out there and dealt with as soon as possible.  I didn't really enjoy Neal Stephenson's last book, REAMDE, past the halfway point because too many improbably occurrences had piled up and my suspension of disbelief didn't recover.  By contrast his newest novel, Seveneves, seems to be doing an excellent job of getting the improbable stuff dealt with quickly and I've been enjoying the book without any hangups.  I've only gotten through chapter 7, acknowledged, but I've got a feeling I'll continue to enjoy this one.

But of course the second improbable thing gives me a chance to talk about some physics I find interesting so I'm going to dissect what I think Stephenson gets wrong.  Not because I think the author is a bad person or wrote a bad book but just because I think the physics is nifty and reading this prompted me to share it.

The basic setup of the book is that the moon is hit by some high energy cosmic event that basically blows it up.  That's improbable thing #1 but hey, we haven't totally figured out physics yet.  After that the moon breaks into seven fragments that go into orbit around each other in a cluster at several times the original diameter of the moon.  The periodically collide with each other and break into more and more fragments.  Our protagonists figure out that eventually they'll break up so much that they'll get away from the old lunar orbit and either collide with Earth or form a new ring.  That's improbable thing #2 and also the driver of the plot.

There are a few things wrong with that but they'll take some explaining.  The first is that size matters and large objects don't behave the same way as small objects.  Way back in 1638 Galileo wrote Discourses and Mathematical Demonstrations Relating to Two New Sciences which is the first I've ever heard of anyone talking about this principle.  Galileo observed that small animals like cats can survive falls much better than large animals like horses even over a couple of meters.  The thing is that a things strength increases in proportion to its cross section but its weight increases as its volume.  So as an animal's length increases its ability to support itself against falls decreases as its length squared over its length cubed, or just inversely proportionally to its length all things being equal.  That's how an ant, say, can lift 40 times its body weight but a human could never do that.

This applies to structures and moons as well as animals.  If you're familiar with 10 cm cubes of stone and want to think about how 1 m cubes behave just pretend that the larger cube is like the smaller but with only 1/10th the strength.  Stone is pretty strong but a humongous cube wont be able to support itself.  The edges will fall off under their own weight and you'll have a pile rather than a cube.  The radius of the moon is over 1,700,000 meters so it would be incredibly fragile if you did something like bring it to the surface of the Earth.  A merely mountain sized mass of rock would crumble into a pile.  Something the size of the moon would flow like water.  That's why all celestial bodies over a certain size end up as spheres rather than the bumpy shapes of smaller moons and asteroids.

So if you were to hit the moon with a big jolt and cause it to break up it wouldn't break up into 7 pieces that would then maybe split in half if they hit each other.  It would be more like the breakup of a mass of dust.

This sometimes goes against our intuitions.  I know I've read 9/11 truther websites where they say that the twin towers can't have just collapsed because when a 10 story building collapses in an earthquake it doesn't look anything like what happened to the World Trade Center.  But really the Twin Towers were 10 time taller and so only one tenth as able to withstand their own weight once it had been unleashed on them and it's no surprise that they could be reduced so completely to rubble.

The other problem is the way the moon overcomes its own gravity when it fragments too far.  When you've got a moon orbiting a planet you've got its own gravity trying to keep it together but you've also got the tidal forces of the planet's gravity trying to pull it apart.  A moon's gravity is just as strong no matter where it is but the planet's pull on the moon and the resulting differential get stronger the closer a moon is to its planet.  There's this thing called the Roche Limit that tells you when a moon is far enough away to stick together and when it's gotten so close that it is pulled apart into a ring system.  And the Earth's moon is way, way out beyond that limit.  It's about 500 km for the Moon when the Moon's actual orbit is way out at 400,000 km.

If you've got a few big hunks of moon orbiting their mutual center of mass then there isn't an obvious path from that to their fragments escaping that orbit.  Now, when rigid objects hit each other and shatter you often have pieces fly off going faster than the objects that collided.  But again that tends to happen with hard objects rather than the effectively very soft objects that the moon chunks would be.

So basically I don't buy the setup in Seveneves.  But it's ok since it's something I swallowed at the start and the rest of the book is good enough to make me forget it so far.

UPDATE:  Finished the book and I really enjoyed it up 'til the timeskip at the 2/3 point and enjoyed it enough after.  I think the book would have been better with an Ender's Game style "And this is what happens in the future" last chapter instead of that last third but I'm still happy with the book overall.

Sunday, May 31, 2015

May Links

Someone made a map of all the languages of Europe arranged by lexical distance.  Looking at it you might wonder why English is considered Germanic but apparently our grammar is distinctly Germanic despite the number of French words we've absorbed.

A lot of the time I tend to just look at the income tax when thinking about progressive or regressive taxation but this blog post reminded me that there are a lot of good and services that have specific taxes attached to them and they tend to disproportionately be things consumed by poor people.  A lot of other good stuff there too.

Some Italian scientists basically just sprayed some spiders with water that had carbon nanotubes in it and found that they made silk stronger than any known material.  That's mad science for you.

Remember those bright spots on Ceres?  As Dawn gets closer we're getting better pictures.  It's looking for like ice.

Our robot made the news!

There's this thing called the Broken Window Theory that basically says that if people can see small pieces of evidence of disorder they'll be more likely to commit crimes.  But people have experimented on the theory itself from a bunch of angles and it's super well confirmed.  Whether the approach New York took to trying to take advantage of it is a good idea is another question.

It's nearly summer so I figured I'd share this post on what drowning actually looks like.  It's not what you'd expect from watching Hollywood movies!

Los Angeles voted to gradually phase in a $15 dollar minimum wage.  This will probably help economists better understand when raising the minimum wage causes more unemployment but there seems to be an emerging consensus anyways.  The unions that fought for the minimum wage increase seem to not want it to apply to them but don't read too much into that.  Unions are usually all about trading wages for more health insurance and working conditions and so forth.  I could write a whole long thing about how in theory taxing the rich to subsidize the poor is much better than increasing the minimum wage.  I probably will at some point.  But the current alternative, the Earned Income Tax Credit has some problems.

Some speculation on mining asteroids, mineral deposit locations as trade secrets, and how to get around that via maritime salvage.  This would make a great basis for a novel.

As most residents know rents around Boston are rising and the number of unfilled units continues to shrink.   Cambridge is looking to reach its 2030 housing goal by 2030 but it seems that most of the municipalities around the Boston area aren't doing that.  Still, it looks like the amount that Cambridge is building is only barely keeping pace with Cambridge population growth.

Sunday, May 24, 2015

Divestment doesn't work

I noticed The Tech, MIT's student newspaper has a front page article on a call for MIT to divest from fossil fuel companies and various faculty members weighing in.  There was some back and forth in it but the thing that I think is most important about divestment wasn't mentioned by any of the participants.  To put it baldly: divestment doesn't accomplish anything.

Now, US universities have about $415 billion dollars in investments between them.  The ten biggest oil companies have a market capitalization of 1,800 billion between them.  So you might think that all universities divesting could lower the stocks of the gas companies by 20% or so.  Except the denominator you want is actually all the money everyone is investing in all stocks, or about $65 trillion.  So without the investments of the universities you'd only expect their stocks to go down by half a percent.

In economics there's something called the efficient market hypothesis which is sort of badly named and also a bit confusing since it comes in three forms.  None of the three forms is perfectly true but some are more true than others.  But the idea here is that if you manage to lower the price of a firm's stock in a way that doesn't lower the stream of dividends that the stock will produce then if people notice they'll swoop in and bid the price of the stock back up.

That process is far from perfect.  For decades the general level of the stock market went down on Friday and up on Monday before someone noticed and made a huge amount of money in the process of causing the effect to disappear.  If you managed to get all the US universities to divest from oil companies without Wallstreet hearing about it you would be able to get your half a percent share price reduction until they heard about it.  But of course this whole divestment movement is intrinsically public so keeping it secret isn't going to happen.

Normally when someone is going about doing something good in an inefficient way I won't complain.  Yes, I care about efficient charity but apathy is worse problem than inefficiency.  In this case, though, activists are going to accomplish literally nothing even if they succeed so I feel justified in saying "Don't do that, do this instead."

What can you do?  The collective action problems that it's so hard to solve by yourself are easy for a government to solve so call your representatives and tell them you'd like to see them act on climate change.  Have a smaller home or apartment than you might otherwise live in and don't run the heat and AC so hard.  Live closer to where you work and drive a smaller car.  There's lots of things to be done that will actually be effective in proportion to how many people do them.  So do those.

Friday, May 1, 2015

Links for March/April

The most exciting stuff over the last month has probably been everything that's happened in genetic engineering via a tool called CRISPR, described in detail here.  This technique has apparently only been around for a couple of years but it's making big waves.  In the blog post where I heard about this some scientists in the comments were predicting that we'd see this used on humans soon and sure enough it seems that the rumors were right and some scientists had altered non-viable embryos.

In other genetic engineering news, some scientists have altered rice to preform photosynthesis in the more efficient way that corn does

Oh, and some people are hoping to use CRISPR to turn elephant embryos into Woolly Mammoths too.

In Mars news there are apparently belts of glaciers running around the planet.  Also this is a really pretty mineral vein formation.

And elsewhere in space, this person did a very good job of putting all the various things in the solar system to scale.

Oh, and a bunch of companies have cool videos of rockets.  Blue Origin was created by the founder of Amazon, Jeff Bezos, and they've finally put out their first video of the space tourism rocket they've been working on.  The capsule made it nearly to space then back to Earth safely but the booster they'd designed to be reusable had a hydraulic problem and crashed, much like SpaceX's first barge landing attempt.  More recently SpaceX's second barge landing attempt was much closer but too much lateral speed broke one of the legs and though you can see the RCS thruster trying valiantly to keep the rocket upright it was not to be.  Back to Blue Origin, they seem to be a ways from their first orbital launch but they're nearly finished with an engine, the BE-4, that the ULA is hoping to use to replace some Russian engines they've been using.

When you think of a normal car the most complicated part of it is the engine.  But for electric cards it's the batteries that are really the part that's hard to get right and that has a bunch of implications for Telsa Moters.

Hitherby Dragons is a fiction blog by Jenna Moran that I've enjoyed reading.  After a long hiatus it's started to update again.

People talk about peak oil but what we really have to worry about is peak energy because there's a straightforward way to turn water and the CO2 in air into hydrocarbons if you've got enough energy to do it.  Lets hope the price of solar panels keeps dropping.  Audi seems to be betting on that because they've been working on getting some decent diesel fuel from this process, much more useful than the methane you get is you do things the simplest possible way.

One of the cool bits of the the trailer for the new star wars movie was the little droid named BB-8 that was essentially a rolling ball with another ball balanced on it.  It's interesting because it's an actual device rather than CG, as you can see when it rolls out on stage here.  Someone put together their ideas about how they would build it.

Saturday, April 11, 2015

Rockets VI: Very nuclear rockets

See also parts IIIIIIIV, and V.

Chemical rockets would be really nice if they were just a bit more energetic.  The energy that goes into pushing the propellant out comes from the propellant itself, so there's stuff you can do to minimize the transmission of heat from the propellant to the rest of your engine.  That helps you get around some of the problems of rockets where you heat up the propellant from outside.  And the fact that you're still basically using heat means you don't have to suffer the efficiency losses that happen turning heat to electricity when you use an electric rocket.  But what sort of reactions are there that we might cause in our propellant that are higher energy than chemical reactions?  I think you've all seen the post title and know that I'm about to say "nuclear."

Now I should make sure to say that unlike the other categories I've mentioned nobody is actively working on any of these.  In the case of some versions that's because there are... problems.  In the case of others it's because we have no idea how to actually build them.  Fusion rockets fall into that later category.  We can do fusion with current technology but the only way we have to get more energy out than we put in is by igniting it with an atomic bomb.

But lets say we solve this problem with cleverness involving lasers or magnetic fields.  We could just inject a little bit of deuterium and tritium into our reaction chamber, ignite it, and then use the resulting plasma to produce thrust.  According to Wikipedia a D-T fusion reaction will produce a helium atom flying out at 13,000,000 m/s and a neutron screaming out at 52,000,000 m/s.  Since the helium has more mass it contributes more to the average velocity, which is 20,000,000 m/s.  Of course that assumes you can cause all of the hydrogen reacts and that the neutron goes in the direction you want it to go.  I have no idea how close an actual rocket could get to this but there it is.

Unfortunately the neutron produced is a bit of a problem with using this reaction for propulsion.  Neutrons tend to transmute other materials which also tends damage whatever the engine is made out of.  Depending on the material it might become radioactive as well or if the rocket is taking off from a planet it might make the launchpad radioactive.  Now there are other sorts of fusion reactions such as between deuterium and helium-3 that don't produce any neutrons at all.  That sort of reaction is harder to create but we don't really know how to do any sort of fusion in a controlled fashion.

What sort of drive in this category do we know how to create?  Well, back in the heady days of the 1950s some people theorized that you could use atomic explosions to send a ship into space.  There was actually a nuclear test in '57 that launched 2,000 pound metal lid into the air at escape velocity.  That wouldn't be an ideal method of getting to space, though, since any crew would be pulped by the acceleration.   The idea that Stanislaw Ulam came up with was to have a large metal pusher plate separated from the main spacecraft by a large shock absorber.  The name of the design was Project Orion.

Now there are a number of disadvantages to this scheme.  The pusher plate and shock absorber are going to be very heavy.  You have all the dangers of neutron activation and protecting the crew from radiation you get from fusion.  Oh, and you've got atomic bombs exploding outside your spaceship.

That's mostly a problem if you're using this thing to take off from Earth.  In space there aren't many things things to damage and space is pretty radioactive anyways outside planetary magnetic fields so nobody is going to worry about the fallout.  On Earth the fallout is much more a cause for concern.  We exploded a lot of big big atomic bombs in the atmosphere when nukes were being developed before the Test Ban Treaty and they increased the typical person's radiation exposure by about .11 Millisieverts per year.  Now, you typically get a couple of mS or radiation a year or maybe 6 if you live somewhere high in elevation like Denver.  But that extra bit could still mean the difference between cancer and no cancer.  The .11mS figure was from around 200 megatons of nuclear fission.  The bombs Orion would use are only 3 kilotons but you'd need a couple of hundred of them to reach orbit so that comes to 600 kilotons of nuclear explosion.  So figure a global radiation dose of .00033 mS per person.  Assume a linear no threshold dose model and a Sievert giving you a 5.5% chance of getting cancer and multiply by the global population and you'd expect 127 cases of cancer per launch.  So not an option unless we need to prevent a giant asteroid from hitting earth or something.  Also the Test Ban Treaty I mentioned prohibits setting off bombs in the atmosphere, I trust you can see why.

This is all something of a shame because the Orion would be a really good rocket.  You'd get an effective ve of over 20,000 m/s combined with really high thrust. Maybe you could assemble one in orbit and use it to take people to Saturn or Mercury or something but as I mentioned the pusher plate system is really heavy and it's hard to get it up to orbit if it's not pushing itself.

So I don't see Orion being a viable option any time soon and fusion isn't something we know how to do.  Maybe someday but not here and now.

Saturday, April 4, 2015

Rockets V: Things that aren't actually rockets

See also parts IIIIIIIV, and VI.

We've covered a bunch of ways of moving ships around in space by shoving stuff out their backs.  But there are some ways of moving around in outer space that actually don't involve the rocket equation at all.  When you fly in a plane on Earth you can push around all that nice air that surrounds you in your environment in order to fly.  Well, you can if you have a plane.  It's very convenient in terms of not having to carry around huge amounts of fuel.  There isn't any air in space but that doesn't mean that space is entirely featureless either.  There are basically three things I know of that you can push off against in order to go places in space: the light of the sun, the solar wind, and planetary magnetic fields.

The principle behind solar sails is pretty simple.  You still have sunlight in space and it's very bright too, at least within Earth's orbit.  By Einstein's good old e=mc2 we know that since light has energy it has to have mass as well and thus momentum to impart when it's been deflected.  Even non-solar sail spacecraft have to take into account the pressure of sunlight if they're going to reach their destinations.  The effect is small since most spacecraft don't have large cross sections in comparison to their masses but if you made your spacecraft very thin you could reasonably use this as your main method of travel.

You might think that solar sails would only be useful in moving away from the Sun, since that's the direction the light is going.  Thankfully orbital dynamics comes to the rescue.  In order for a satellite around Earth to stay in orbit and not fall back down it has to be traveling around 7,800 m/s.  By the same principle the Earth is only able to avoid falling into the sun because it's traveling at 30,000 m/s around the sun.  By deflecting light in the same direction it's traveling a solar sail can slow down in its orbit around the sun and fall into a lower orbit.

And just like ion drives have already been used by Dawn a solar sail has already been used by a Japanese space probe, IKAROS, sent sunwards to go take a look at Venus and to test out solar sails.  Look here for a picture of the probe with its sail deployed.  What's really nifty is that it's got solar panels and LCDs build right into the sail.  The cells are for power and the LCDs enable IKAROS to control its orientation.  The sunlight will exert more force on reflective surfaces than non-reflective ones and by changing the LCDs from white to black the probe can control the forces on different parts of itself.  The entire probe is spinning slowly so that the centrifugal force keeps the sail deployed.

How fast does it go?  Well according to Wikipedia the radiation pressure from Sunlight around Earth is 9.8 µN/m2.  That's for absorption so double it to 19.6 µN/m2 for a perfect reflector.  The sail IKAROS has weighed 10 g/m2 so a square of that material would accelerate at about .002m/s2 if it's out in space by itself.  That's more than the solar ion drive spaceship we looked at but less than the nuclear ion drive one.  Of course there's still the mass of the everything else.  IKAROS weighed 315 kg all told and had 200 m2 of sail.  That gives .000012 m/s2 of acceleration which is pretty tiny but then again it uses literally zero fuel.  Also these guys get better the closer you get to the sun.  Around the orbit of Mercury they accelerate 6 times faster than out here around Earth.  So if you want to take a solar sail to the outer planets it makes sense to drop in near the sun, pick up speed there, and then coast to your destination where you'll need to find some other form of propulsion for stopping.

On to other things.  Besides light the sun spits out a stream of charged particles, the solar wind.  Unlike with sunlight we don't tend to notice because the Earth has a gigantic magnetic field that intercepts these particles and traps them in the Van Allen belts.  That's a good thing because these particles are a form of ionizing radiation and you'd accumulate an unhealthy dose after being exposed to it for a couple of years.  The astronauts at the ISS are safely inside the Earth's magnetic field but the Apollo astronauts were exposed to it for a week and it'll be a big concern for any astronauts going to Mars.

But wait, we just said that are all these fast moving particles that are being stopped by Earth's magnetic field.  Doesn't that mean that they're giving their momentum to Earth?  Yes it does.  The idea behind a magnetic sail is that you use a huge magnetic field to deflect these particles and use the momentum to propel your ship.  The solar wind has much less momentum to give than sunlight but since you just need to intercept them with a magnetic field rather than a mirror the idea is that you can make your sail much bigger for the same mass and so end up accelerating faster.  Another idea is to use electric fields to repel the solar wind rather than magnetic fields and the electric sail is something being worked on now by the European Space Agency.  It's easier to make but harder to control the direction of thrust.

Finally we have the direct use of a planet's magnetic field.  If you run a current through a wire that is in a magnetic field you get a force.  If you're got a nice electrodynamic tether in orbit you can either trade the kinetic energy of your spacecraft for electrical energy or use electrical energy to increase the kinetic energy of your spacecraft.  When you're boosting the trade offs are essentially identical to those of other sorts of electrical drives except you have to do it in a magnetic field and you don't have to use propellant.  When you're braking, on the other hand, you get paid to slow down and that's really nice.  You do need a handy source of electrons to grab to run through the wire but thankfully they don't call it the ionosphere for nothing.  There's at least one company seriously working on these.

So there you have it, three sorts of useful space non-rockets.  They're not as far along as electric thrusters but they're certainly possible.

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