Tag Archives: Project

Galaxy Calc Shows Aliens

What makes a planet a good host for life? That is, what does a planet need for life to originate there and then evolve to something at the human level? Astronomers today say a planet at least needs a star that 1) lasts long enough, 2) has enough heavy elements, and 3) is not too often hit by nearby supernovae or gamma ray bursts. Using such criteria, several astronomers (mentioned below) have tried to calculate “galactic habitable zones,” i.e., galactic distributions of good-for-life planets, in both space and time. Such calculations are far more important than I had realized – they can help say how common are aliens! Let me explain.

Imagine that over the entire past and future history of our galaxy, human-level life would be expected to arise spontaneously on about one hundred planets. At least it would if those planets were not disturbed by outsiders. Imagine also that, once life on a planet reaches a human level, it is likely to quickly (e.g., within a million years) expand to permanently colonize the galaxy. And imagine life rarely crosses between galaxies.

In this case we should expect Earth to be one of the first few habitable planets created, since otherwise Earth would likely have already been colonized by outsiders. In fact, we should expect Earth to sit near the one percentile rank in the galactic time distribution of habitable planets – only ~1% of such planets would form earlier. If instead advanced life would arise on about a thousand planets, Earth should sit at the 0.1 percentile rank. And if life would arise on a thousand planets, but only one in ten such life-full planets would rapidly expand to colonize the galaxy, Earth should again sit near the one percentile rank.

Turning this argument around, if we can calculate the actual time distribution of habitable planets in our galaxy, we can then use Earth’s percentile rank in that time distribution to estimate the number of would-produce-human-level-life planets in our galaxy! Or at least the number of such planets times the chance that such a planet quickly expands to colonize the galaxy. If Earth has a low percentile rank, that suggests a good chance that our galaxy will eventually become colonized, even if Earth destroys itself or chooses not to expand. (An extremely low rank might even suggest we’ll encounter other aliens as we expand across the galaxy.) In contrast, if Earth has a middling rank, that suggests a low chance that anyone else would ever colonize the galaxy – it may be all up to us.

At the moment published estimates for Earth’s time percentile rank vary widely. An ’04 Science paper (built on an ’01 Icarus paper) says: Continue reading "Galaxy Calc Shows Aliens" »

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New Is Not Better

“As a non-American, I don’t completely understand it, but there is a phenomenon in the U.S., the latest and the greatest. … There was a patient demand to get these implants on the misconception that the latest was the best.” …“The vast majority of the ‘innovations’ on which we have spent money with respect to orthopedics over the past two decades have not resulted in improved patient outcomes.” (more; HT Tyler)

Assuming no side-effects, if users gain from innovations then innovators must gain less than the social value of their innovations, which risks their having insufficient incentives to innovate. This effect can be countered, however, by giving extra social status to the creators and users of innovative products, services, and behaviors.

United States culture gives such extra status to creators and users of innovations, and so probably deserves some credit for encouraging innovation. But alas much of this is wasted via merely rewarding things things that are new, rather than innovative. And if your reaction to reading that was “what is the difference?,” that just shows the depth of the problem.

Innovative things must be new, but new things need not be innovative. To be usefully innovative is to be better some how. Innovators try many new things, most of which are not better, but a few of which are. On average new things are w0rse, but those that are eventually retained are hopefully on average better. And with the right incentives, the retained better things are so much better that they pay for all the other new worse things.

If our culture waited until it was clear which new things were actually better, and gave more status to the creators and early adopters of those things, culture would promote innovation. But alas culture instead mainly showers status on those who merely create and use new things, regardless of whether they are better. While in small amounts even this status effect can promote innovation, in larger amounts it can hurt. After all, when there is too little added reward for creating or using something that is both new and better, relative to something that is just new, people will mainly focus on the new part.

The problem comes from an excess focus on current behavior, relative to past track records. In enforcing social status norms, it is relatively easy to just see that someone is today affiliated with with something that is new today, and give that person credit for their newness. It is much harder to remember that a person was once affiliated with something that was then new, and which later turned out to actually be better. A mechanism that made it easier to collect and view such track records could be of great social value, at least if combined with new matching social norms on who deserves social credit for being “innovative.”

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Dreamtime Finance

In 1956, John Kelly introduced his “Kelly criteria” betting strategy: bet on each possible outcome in proportion to (your estimate of) that outcome’s chances of winning, regardless of the betting odds offered. More generally, a Kelly rule invests in each possible asset in proportion to its expected future payout, regardless of current asset prices. For example, if you estimate land will be worth 30% of world wealth in the distant future, you put 30% of your investments into land today, regardless of today’s land prices.

It turns out that the Kelly rule is close to the optimal long run investment plan, i.e., the one that would win an evolutionary competition. The exact best strategy would consider current prices and expected future price trajectories and carefully choose investments to max expected growth, i.e., the expected log of a distant future portfolio. But Kelly’s rule is far simpler, gets better than average growth regardless of state, time, or prices, and approaches the exact best strategy as good strategies come to dominate prices. In fact:

A stock market is evolutionary stable if and only if stocks are [price] evaluated by [Kelly rule] expected relative dividends. Any other market can be invaded in the sense that there is a portfolio rule that, when introduced on the market with arbitrarily small initial wealth, increases its market share at the incumbent’s expense. (more)

(More on evolutionary finance here, here, here, here; see especially this review.) We’ve had big financial markets for at least a century. Has that been long enough for near-optimal strategies to dominate? Not remotely. John Cochrane explains just how bad things are:

We thought returns were uncorrelated over time, so variation in price-dividend ratios was due to variation in expected cash flows. Now it seems all price-dividend variation corresponds to discount-rate variation. We thought that the cross-section of expected returns came from the CAPM. Now we have a zoo of new factors. … For stocks, bonds, credit spreads, foreign exchange, sovereign debt and houses, a yield or valuation ratio translates one-for-one to expected excess returns, and does not forecast the cash flow or price change we may have expected. In each case our view of the facts have changed 100% since the 1970s. …

All of these facts and theories are really about discount rates … and risk premiums. None are fundamentally about slow or imperfect diffusion of cash-flow information, i.e. informational “inefficiency.” Informational efficiency isn’t wrong or disproved. Efficiency basically won, and we moved on. When we see information, it is quickly incorporated in asset prices. … Informational efficiency is much easier for markets and models to obtain than wide risk sharing or desegmentation, which is perhaps why it holds more broadly. (more)

Got that? Finance prices today do a great job of aggregating info – relative prices between similar assets are great predictors of relative payouts. But when it comes to broad price aggregates, such as stocks in general or land in general, price changes basically reflect crazily-changing values. While in markets dominated by near-optimal traders, prices would only change when expected future payouts changed, in fact aggregate prices changes have almost no relation to matching future payouts changes. For example, land prices change plenty (as in the recent real estate bubble), but aggregate land price changes say almost nothing about future land rents.

I’ve talked before about how our era is a rare extreme “dreamtime,” with fast change and behavior quite out of equilibrium with evolutionary selection pressures. We not only have dreamtime fertility, i.e., far fewer kids per couple than selection would favor, we also have crazy-price dreamtime finance. This allows a relatively clear prediction of the future: finance will eventually “equilibrate.” Either the world will coordinate to block the creation of investment funds following near Kelly rules that reinvest most gains, or financial prices will eventually come to be dominated by such near-Kelly funds.

Once dominated by near-Kelly funds, finance prices will no longer suffer huge crazy booms and busts, like the recent dotcom boom or real-estate crash. Furthermore, interest rates should fall dramatically — future returns will no longer be discounted intrinsically, but only for opportunity cost reasons.

Apparently many funds today do now follow near Kelly rules:

The claim has been made that well-known successful investors including Warren Buffett and Bill Gross use Kelly methods. (more)

So the main barrier seems to be fund ability and inclination to reinvest most gains. As I wrote a year ago:

Many folks would be willing to create trusts that accumulated funds long after their death and then paid distant descendants (perhaps indirectly) to do things like remember their ancestor’s name, pray to his gods, etc. Unless stolen, such funds would eventually come to dominate the world economy and dramatically lower interest rates. With lower interest rates … businesses and governments would have far stronger incentives to attend to the interests of distant future folks, such as via global warming policies. But we in fact refuse to enforce a great many such long term deals. (more)

In a large decentralized world, however, I doubt this barrier will stand. Nor can I see why it should. I for one welcome our new financial overlords. Seriously.

I wonder if anyone could estimate how long it should take Buffett/Gross size Kelly funds to dominate finance prices. More Kelly rule details from that review: Continue reading "Dreamtime Finance" »

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The SETI Game

When listening for signals from aliens, it isn’t enough to just point an antenna at the sky. One must also choose details like directions, angles, frequencies, bandwidths, pulse widths, and pulse intervals. Apparently most SETI searches assume that for a given signal power density, aliens would pick details to make it as easy as possible for us to detect their signals. So standard SETI searches are optimized for such easily-seen signals. Two excellent papers, published back in July, instead consider what sort of signals would be sent by “beacon” building aliens, who seek to create the maximum possible power density at any given distance away from them.  (One of the authors is SF author Greg Benford.) Such signals are quite different, and most of today’s SETI searches are not very good at seeing them:

Minimizing the cost of producing a desired power density at long range … determines the maximum range of detectability of a transmitted signal. We derive general relations for cost-optimal aperture and power. … Galactic-scale beacons can be built for a few billion dollars with our present technology. Such beacons have narrow “searchlight” beams and short “dwell times” when the beacon would be seen by an alien observer in their sky. … Cost scales only linearly with range R, not as R2. … They will likely transmit at higher microwave frequencies, 10 GHz. The natural corridor to broadcast is along the galactic radius or along the local spiral galactic arm we are in. …

Cost, spectral lines near 1 GHz, and interstellar scintillation favor radiating frequencies substantially above the classic “water hole.” Therefore, the transmission strategy for a distant, cost-conscious beacon would be a rapid scan of the galactic plane with the intent to cover the angular space. Such pulses would be infrequent events for the receiver. Such beacons built by distant, advanced, wealthy societies would have very different characteristics from what SETI researchers seek. … We will need to wait for recurring events that may arrive in intermittent bursts. …

A concept of frugality, economy. … directly contradicts the Altruistic Alien Argument that the beacon builders will be vastly wealthy and make everything easy for us. An omnidirectional beacon, radiating at the entire galactic plane, for example, would have to be enormously powerful and expensive, and so not be parsimonious. … For transmitting time t, receiver detectability scales as t1/2. But at constant power, transmitter cost increases as t, so short pulses are economically smart (cheaper) for the transmitting society. A 1-second pulse sent every 10 minutes to 600 targets would be 1/600 as expensive per target, yet only *1/25 times harder to detect. Interstellar scintillation limits the pulse time to >10-6 s, which is within the range of all existing high-power microwave devices. Such pings would have small information content, which would attract attention to weaker, high-content messages. …

Cost-optimized beacons … can be found by steady searches that watch the galactic plane for times on the scale of years. Of course, SETI literature abounds with consideration of the trade-offs of search strategy (range vs. EIRP vs. pulse vs. continuous (continuous wave, CW) vs. polarization vs. frequency vs. beamwidth vs. integration time vs. modulation types vs. targeted vs. all-sky vs. Milky Way). But, in practice, search dwell times are a few seconds in surveys and 100–200 seconds for targeted searches. Optical searches usually run to minutes. And integration times are long, of order 100 s, so short pulses will be integrated out. …

Behind conventional SETI methods lies the assumption that altruistic beaming societies will send persistent signals. In searches to date, confirmation attempts, when the observer looks back at a target, in practice usually occur days later. Such surveys have little chance of seeing cost-optimized beacons. … Distant, cost-optimized beacons will appear for much less time than as assumed in conventional SETI. Earlier searches have seen pulsed intermittent signals resembling what we (in this paper) think beacons may be like, and may provide useful clues. We should observe the spots in the sky seen in previous work for hints of such activity but over year-long periods. (more)

Of course both the usual assumption that aliens will pay any cost to make a given power density signal easy for us to see, and the new assumption that aliens ignore our costs and merely seek to maximize power density, are both somewhat unsatisfactory. It would be better to model this interaction as a game, where each side has a limited budget and seeks to maximize the probability of at least one successful communication, holding constant the behavior it expects from the other side. Each side would of course also have to integrate over possible locations and budgets for the other side.

I’m very interested in working with (sim, math, or physics) competent folks to more formally model this SETI communication game.

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On Berserkers

Adrian Kent is getting a little publicity for posting his ’05 paper on the berserker hypothesis, “that evolution has very significantly suppressed cosmic conspicuity”, i.e., that many aliens are out there, but hiding from each other. He advocates taking the hypothesis seriously, but doesn’t actually argue for the coherence of any particular imagined scenario. Kent’s excuse:

It would be very difficult to produce a model that convincingly predicts the likelihoods and spatial distributions of the various strategies, since the answer surely depends on many unknowns.

He instead just claims:

The hypothesis is certainly not logically inconsistent and it seems to me not entirely implausible.

So what then is Kent’s contribution? Apparently it is a bunch of strategy fragments, i.e., strategy issues that aliens might consider in various related situations. It is not clear that these are much of a contribution, at least relative to the many contained in related science fiction novels. But, well, here they are: Continue reading "On Berserkers" »

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Peer Review Is Random

Which academic articles get published in the more prestigious journals is a pretty random process. When referees review an academic paper, less than 20% of the variability in referee ratings is explained by a tendency to agree:

This paper presents the first meta-analysis for the inter-rater reliability (IRR) of journal peer reviews [using] … 70 reliability coefficients … from 48 studies. … [covering] 19,443 manuscripts; on average, each study had a sample size of 311 manuscripts (minimum: 28, maximum: 1983). … The more manuscripts that a study is based on, the smaller the reported IRR coefficients are. .. If the information of the rating system for reviewers was reported in a study, then this was associated with a smaller IRR coefficient. … An ICC of .23 indicates that only 23% of the variability in the reviewers’ rating of a manuscript could be explained by the agreement of reviewers. (more: HT Tyler)

reviewreliability

The above is from their key figure, showing reliability estimates and confidence intervals for studies ordered by estimated reliability. The most accurate studies found the lowest reliabilities, clear evidence of a bias toward publishing studies that find high reliability. I recommend trusting only the most solid studies, which give the most pessimistic (<20%) estimates.

Seems a model would be useful here. Model the optimal number of referees per paper, given referee reliability, the value of identifying the best papers, and the relative cost of writing vs. refereeing a paper. Such a model could estimate losses from having many journals with separate referees evaluate the each article, vs. an integrated system.

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Jobs Explain Lots

Different people do different things; why? When we look features of individuals to explain their differing individual behavior, there are a few favorites: age, gender, race, income, education, IQ, and personality-type. Some people look at location, such as zipcode or nation. But it seems to me that one’s job (i.e., occupation) is a neglected strong predictor of many interesting things. For example:

  • A few days ago I blogged on a recent study of how jobs predict the chances of divorce. Job risk-ratios range over about a factor of two, after controlling for age, gender, race, and income.
  • I start my health econ class with this ’99 study of how jobs predict death rates. Job risk-ratios range over about a factor of two, after controlling for age, gender, race, income, and education. (Key chart below the fold.)
  • A February analysis found occupation strongly predicts the direction of political contributions, and an ’07 study said academic discipline strongly predicts professor political affiliation. This page of aneqdotes suggests that jobs often predict political affiliations well.

More generally, I’d love to see a factor analysis seeking the few strongest job factors that can simultaneously predict variations in divorce, mortality, political affiliation, and whatever else interesting one can throw into the mix. Seems like a great project for a data-oriented grad student. Continue reading "Jobs Explain Lots" »

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Brave Position Club?

At my post yesterday on race, several comments accused me of cowardice for not taking a position there on race-IQ correlations, even though that is not directly relevant to the post, and even though I have commented on that topic before. While I mostly don’t avoid taking positions on controversial topics if I think I have something interesting to say about them, I also don’t go out of my way to take controversial positions just to take them. Apparently some folks, however, take pride in going out of their way to take controversial positions even when they have nothing interesting to say on such topics.

I suppose I can appreciate that some folks want to signal they don’t fear social retribution, though I suspect many interpret them as signaling that they have no political or managerial ambitions.  But it occurs to me that folks could be more systematic about this signal; imagine a Brave Position Club.

The Brave Position Club would have an official long list of, perhaps 100, brave topics, and club members would simply be defined as folks who had publicly declared a clear current position (perhaps chosen from a menu) on all those brave topics. The topics should be chosen to be the most socially awkward topics, ones for which people typically fear the most social costs for taking certain positions.  The topics should also be chosen neutrally, so as to “gore everyone’s oxen” equally, rather than to preferentially expose the hypocrisies of certain disfavored groups.

The topic list should be long enough so that people who chose positions by “thinking for themselves” would likely choose socially-awkward retribution-worthy positions on at least a few of the topics. A club member who declared the safe opinion on all the brave topics would be clearly identified as a “kiss-ass brown-noser” who didn’t think for themselves.

I’d be tempted to join such a club, at least if some careful analysis had gone into picking the topics neutrally, and if I expected enough other folks to join for it to become focal.  Would you join?  Who should join and why?

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Price Conspiracies

A believable conspiracy theory:

Airlines and online travel agencies surreptitiously use computer “cookies” they’ve implanted on your Web browser to track your activity on their sites and then raise prices when it appears that you’re interested in a fare. That’s the rumor, at least. … For years … the industry … has vehemently denied any tampering with prices. …

A United Kingdom-based hotel site called VivaStay reportedly dinged customers by way of a special link from an affiliated Web site that showed slightly higher prices than those quoted to customers who clicked directly on the VivaStay site. VivaStay apologized, but said it was unaware that the price variation was frowned upon.  …

A teacher … says … she recently tried to buy a ticket to Vietnam … through the Delta Air Line Web site. … But when she was actually ready to buy her flights, the airline informed her that the ticket she wanted was $300 more than the original price quote. … “I returned to Delta’s home page and began the process again. … The same lower fare was still displayed, so I worked my way through the process again only to be informed once again that the fare was no longer available. Over the course of a half hour I repeated this process two more times. Same result.” …

“If there is no bias in a process, there are about as many negative outcomes as positive outcomes. The process of posting the lower airfares — that is, making them initially available — should result in as many surprisingly lower prices at booking as it does surprisingly higher ones because they have all been taken.”  [This physicist] makes a good point. I’ve heard of only one or two cases where the fare dropped.

Given a room full of computers, such as in a school or library, it shouldn’t take more than a few hours to test this price-jump conspiracy theory.  Just try to book random flights and record the initial and final prices offered.  If the non-random pattern is strong, it shouldn’t take long to see clearly.

Price discrimination, i.e., charging different prices for the same thing (that costs the same), has long been a wide-spread business practice.  Firms are reluctant to admit they do it not only because customers get mad, but also because it has been illegal in the US since the 1914 Clayton Antitrust Act, at least if “the effect … may be substantially to lessen competition.”  Mark this as another bendable rule authorities rarely enforce, letting them selectively punish whomever they wish.

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Robots vs. Aliens vs. …

There are a many kinds of potentially powerful creatures one might consider.  These include: robots, aliens, spirits, gods, alters, revived hominids (e.g., neanderthals, hobbits), time-travelers (e.g., ancestors, descendants), and extreme human personality types (e.g., aspergers, psychopaths).

For each creature type, consider the degree to which you might:

  1. accept/want to live intermingled with them?
  2. seek/expect to gain via deals & trade with them?
  3. worry if they have similar enough values?
  4. exterminate them if you could?
  5. enslave them if you could?
  6. hide us from them if you could?
  7. fear them killing us all?
  8. fear them enslaving us?
  9. fear them out competing us?
  10. mind them marrying your child?
  11. take their advice?
  12. mind killing a single one of them?
  13. help them lots if that were cheap for you?
  14. mind becoming one of them?
  15. mind if they dominate the universe?

OK, now here is the interesting meta question: what patterns are there in how different sorts of people answer these questions differently for the different possibly-powerful creature types?  Once we have some patterns, we can seek explanations for them.

For example, compared to other types of creatures, we seem to less fear alters having differing values or our-competing us, seem more willing to take their advice and kill them, but seem less willing to enslave them.

Added 7Apr: For spirits or time-travelers, stories about dominance or gift-exchange relations sometimes go well, but stories about trade relations usually go very badly.

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