Analog SFF, May 2011
Page 13
Finally they showed us the game stations. Rows and rows of computers, all fast as lightning with top-end graphic cards and optical links to the Internet. They told us to dig right in. Pick our favorite games and go for it. Don't come up for air until you want to. It was like Christmas in July.
I wondered if this was some sort of trick, like when Mom caught me sneaking Halloween candy and made me eat nothing else for a week. I couldn't stand the stuff after that. If she thought that would happen with online games, though, she was in for a surprise. I could play games for a solid year. Heck, I pretty much had played games for a solid year, and then some.
So all us kids said goodbye to our parents, shooing them off home as fast as we could, then we rushed to the computers and got down to business.
I chose Vortex. That's my favorite. Earth has been sucked into a giant wormhole and spit out into a chaotic mess of alien planets from all over the galaxy. You can explore, fight, and sim pretty much forever.
I typically run half a dozen characters at once. The counselors were cool with that, and encouraged me to do more if I could. They even had some custom bots that let my characters run on automatic, picking up gold and strength and stuff on their own. Each bot used a separate account, which I thought was a little odd, but hey, the camp was paying for it. Pretty soon I had, like, twenty characters all running around getting stronger and richer by the moment. It was awesome.
Then I pissed off one of the counselors. I don't know what I did, really; she just got all weird about my Mountain Dew bottles spilling out of my cubicle and took away one of my characters. Of course it was the one with the biggest stash.
I didn't care. I had nineteen others. And when the counselor left, I just created another one and ran it through the vortex until I was right back where I'd been before.
Then another kid got docked a character. And another. Pretty soon we were all losing characters for petty little infractions, stuff like making fart noises or whacking off in the bathroom. I mean, we're teenage boys; what do they expect?
Then Jared, the kid in the cubicle next to mine, found his character for sale on eBay. They'd filed off the serial numbers, but it was clearly his character, with all the same strengths and bling, and they wanted, like, three hundred bucks for it.
Jared was like, “This totally sucks.” I did a little digging and found my character in an old auction, one that had gone for almost five big ones. That's real iTunes and phone app money.
A dozen of us held a midnight meeting in our dorm to figure out what we were going to do about it.
"It's called ‘gold farming,'” Jared said. “I read about it on Wikipedia. Adults get kids to build up characters and then sell them to lazy people who don't want to do it themselves."
"Let's tell our parents,” said Steven, one of the littlest kids in the group.
"No way,” the rest of us said. “We take care of this ourselves."
"We could expose what they're doing on Facebook,” an older kid named Greg said, but nobody liked that idea, either.
"We could hack the counselors’ passwords and blow their credit ratings,” someone else said. That generated some excitement, but it still didn't seem quite right. We wanted something they couldn't do anything about, but would shut them down for good.
Then I got my brilliant idea. “How about we do nothing?” I said.
They all looked at me like I'd suggested we kiss girls or something. “Stop paying games for them,” I explained. “They said we could go hiking and canoeing and camping any time we wanted; let's do that instead."
We killed off all our characters first, of course, and then we headed for the woods. I wound up with a suntan, poison ivy rash, the beginnings of biceps, but it was worth it to see the looks on the counselors’ faces. Day after day we hiked and paddled and cooked s'mores around the campfire while the computers gathered dust. I even learned to fish.
When I got home, I went straight to my room and did a weekend Vortex run. I built up a character to level 90, then sold it on eBay for seven hundred bucks.
Of course I just blew it all on a kayak. That's the downside to this outdoor stuff: once you get into it, it's really addictive.
Copyright © 2011 Jerry Oltion
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Department: THE ALTERNATE VIEW: ‘GOLDILOCKS’ GLIESE 581G: A FAIRY TALE? by John G. Cramer
In October 2010 the headlines of the science press were dominated by the announcement of the discovery of a “Goldilocks Planet,” Gliese 581g, which has a mass not too different from that of the Earth and has an orbit squarely in the middle of the habitable zone of its parent star. It was supposed to be not too hot, not too cold, but just right for the evolution of life. Steven Vogt of UC Santa Cruz, the lead author of the paper, was quoted (out of context) as saying, “The chances of life on the planet are 100%.” Now that some of the dust has settled concerning this reported discovery, I'd like to have a look at the work behind the announcement and consider its present status.
First, I want to review how such extrasolar planets are now being discovered. The principal technique is to observe a star repeatedly over a long period of time, measuring its radial velocity (i.e., its speed along the line of sight towards the observer), based on spectral-line wavelength variations due to the Doppler shift. When a planet orbits a star, its gravitational pull on the star causes small shifts in the position of the star's center of mass that show up as time-dependent changes in radial velocity. Astronomers have developed very sensitive multiple-grating spectrograph instruments that can measure such radial velocity variations of a star down to about one meter per second.
This is the technique that was used at the Keck Observatory by the Vogt group to study Gliese 581, a class M3V red dwarf star with a mass about 1/3 that of our sun. Gliese 581 is a distance of about 20 light years from the Earth. The Vogt group combined 122 precision measurements of their own of the radial velocity of Gliese 581 taken at the Keck Observatory over a period of 11 years with 119 similar measurements with somewhat better resolution from a Swiss group taken over a period of 4.3 years.
Previous work by other groups of astronomers using the radial velocity technique had already identified four planets of the Gliese 581 system: Planet-b, a “hot Neptune,” with 17 Earth-masses and a 5.37 day orbit, Planet-c with 5.06 Earth-masses and a 12.931 day orbit, and Planet-d with 8.3 Earth-masses and a 66.8 day orbit. (The letters start with “b” because “a” is the star itself.) There was also some indication of “Mercury-like” Planet-e with 1.7 Earth-masses and a 3.15-day orbit. Planet-c lies at the Venus-like inner edge of the habitable zone of Gliese 581, and Planet-d is at the Mars-like outer edge of the star. Several studies have already suggested that, given the presence of an atmosphere that produced a strong greenhouse effect for extra heating, the “super-Earth” Planet-d might represent a good opportunity for finding evidence of life on an extrasolar planet.
The Vogt group analyzed their combined 241-measurement data set using Fourier analysis, which is a way of converting time-sequence data to a “power spectrum” of frequencies corresponding to the orbital frequencies of hypothetical planets. They modeled masses and orbits of possible planets, adding one planet at a time and observing the effect of each planet on the frequency power spectrum, then removing its effects. They chose to restrict the parameter set by assuming that all orbits were circular and had 90 degree inclinations, i.e., all planets orbited in the same plane that was being viewed edge-on from the Earth. They started with the previous work and added planets until they obtained a satisfactory fit to the Fourier frequencies. This involved reducing the so-called “False-alarm Probability” to a value on the order of 1 in 100,000. They found that they needed to assume a six-planet system in order to do this.
In particular, the analysis produced indications of two new planets, Gliese 581f, an outer planet with a mass of 7.0 earth-masses and a 433-day orbit, and Gliese 581g, orbiting between planets c and d with a mass of 3.1 earth-masses and a
36.6-day orbit. The orbit of planet Gliese 581g would be in the middle of the star's habitable zone. If it had the same average mass per unit volume as the Earth, its mass would give Gliese 581g a surface gravity of about 1.5 g.
Not all combinations of planetary orbits are stable, because orbiting planets interact gravitationally with each other, often leading to collision and ejection events. The Vogt group has analyzed the orbital stability of the system of Gliese 581 planets produced by their fit. They concluded that the six-planet system was stable at least to a 50 million year time scale. This stability tends to support the model system they deduced, but that may be related to their assumption of a coplanar planetary system with circular orbits, since many instabilities are associated with orbit eccentricities and differences in orbit inclinations.
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Within a few weeks after the media circus caused by the announcement of “Goldilocks” Gliese 581g, the Swiss group that had produced some of the data analyzed made their own announcement. Their group, analyzing additional data, had been able to find no sign of the Vogt group's two new planets.
Their original data set of 119 measurements of radial velocity taken over 4.3 years had been expanded to 180 measurements that had been taken over 6.5 years, with improved accuracy in the radial velocity measurements. At a conference in Turin, Italy, the group announced that analysis of this enlarged data set showed no evidence of the two new planets claimed by the Vogt group.
That result is disturbing, but perhaps not surprising. The Vogt group had separately analyzed the Keck and Swiss data and had not found evidence for the two planets in the data sets, taken individually. In any case, the results of the Vogt group remain unconfirmed, and the Swiss analysis casts some doubt on the validity of its predecessor.
Since I have some experience in data analysis, I can also complain a bit about how the Vogt group did their analysis. The procedure of putting in one planet at a time and re-analyzing the residuals after its effects are subtracted is not optimal and can lead to serious systematic errors. The proper procedure is to do a simultaneous non-linear least-squares or maximum likelihood search, varying all the parameters of the model together or in groups and obtaining a fit from this minimization. Further, the assumptions of 90-degree inclination and zero eccentricity circular orbits seem questionable. It is still possible that the Vogt group has found a Goldilocks planet, but I would not take it seriously until there is an independent confirmation.
As a start, a new analysis should be performed that combines the new Swiss data with that of the Vogt group, and a more optimal fitting procedure should be used. If Gliese 581g still appears, I would take this as a sign of encouragement, but I would still like an independent confirmation.
However, this is a science fiction magazine, and the discovery of a new planet is an exciting prospect for contemplation and for story writing. Assuming that Gliese 581g actually exists, would the planet really be Earth-like? Almost certainly not. There are several potential problems, all arising from the fact that Gliese 581 is a relatively small and dim class M3V red dwarf star. First, small stars tend to be relatively unstable and may go through fluctuation events producing large stellar flares that could periodically clean its planets of life. Fortunately, Gliese 581 appears to be more stable than many stars of its stellar class, so that might not be a problem. Second, from astronomical observation of spectral lines in the starlight from Gliese 581, we know that it is relatively poor in metals as compared to our Sun. The chain of processes leading to the development of life could encounter some showstopper in a metal poor environment because some key element or chemical compound is not sufficiently abundant.
A third problem comes from the tidal forces (see my AV 63 “The Force of the Tide") that the primary star exerts on its planets. Because Gliese 581 is such a small, dim star, the habitable zone of orbits is much closer to the primary star than is the case in our Solar System. In fact, the mean distance of Mercury from our Sun is about 2.5 times greater than the orbital distance from its primary calculated for Gliese 581g. The star itself, at about 1/3 of a solar mass, would still have a radius about 70% of that of our Sun, but the planet's orbital distance would only be about 15% that of the Earth from the Sun. Therefore, the sky of Gliese 581g would be dominated by the primary star, which would appear 4.6 times larger across in the sky than our Sun appears in our sky. The tidal force that a primary star exerts on its planets depends on the third power of the linear angle in the sky of the planet that the star subtends. This leads to the conclusion that the tidal force of its primary on Gliese 581g would be about 100 times stronger than the tidal force that the Sun exerts on the Earth.
This means that the planet would be tide-locked and probably somewhat pear shaped. It would always present the same side to the star as it orbited. It would have a hot side toward the star, a cold side away from the star, and perhaps a more habitable band somewhere around the equator. If it had water, most of it would be frozen on the dark side of the planet and there would be no oceans. The same might apply to the atmosphere, if the dark-side temperatures dipped low enough to liquefy nitrogen, oxygen, and other gases. Goldilocks or not, Gliese 581g would not be very Earth-like.
However, life tends to exist by exploiting an energy flow, as with the Sun illuminating the Earth or superheated water flowing out of volcanic vents in the ocean floor. The temperature gradient across the equator of Gliese 581g should represent an energy flow that could be a basis for some form of life.
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Are there Goldilocks planets out there, more Earthlike than Gliese 581g? Very likely there are, and we can expect to find some of them in the years to come. Astronomers are getting better at measuring variations in radial velocity, and better techniques involving interferometry and star shades are in the pipeline. NASA's Kepler Mission, launched in March 2009, is presently surveying a list of 145,000 stars for signs of light emission variations caused by planets momentarily eclipsing a part of the parent star as they orbit. The mission is working and data is coming in. As of December 2010, Kepler has discovered eight new extra-solar planets, but none so far falls in the Goldilocks planet category. The Earth-like planets are out there, and we will find them. However, I don't think that we have found any yet, except the Earth itself.
AV Columns Online: Electronic reprints of over 150 “The Alternate View” columns by John G. Cramer, previously published in Analog, are available online at: npl.washington.edu/av.
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References:
"The Lick-Carnegie Exoplanet Survey: A 3.1 Mo Planet on a Habitable Zone of the Nearby MeV Star Gliese 581,” Steven S. Vogt, R. Paul Butler, E. J. Rivera, N. Haghighipour, Gregory W. Henry, and Michael H. Williamson, accepted for publication in Astrophysics Journal, preprint ArXiv: 1009.5733v1 [astro-ph.EP].
Copyright © 2011 John G. Cramer
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Short Story: THE OLD MAN'S BEST by Bud Sparhawk
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Illustrated by Mark Evans
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Ah, the lengths to which homesickness will drive people!
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"I need a beer, Tommy. I really, really need a beer!"
Hearing these words through his helmet radio while hanging suspended 200,000 kilometers above Jupiter startled Allen so much that he lost his grip on the three hundred meter length of sulfoplastic strut he'd been trying to cajole into place. “Eh?"
"I said I need a bloody damned pint-a,” barked the reply from Angus, his partner and the white suited figure at the other end of the strut. “Careful, Tommy. I've poor enough hold to keep this bugger steady as it is."
"Sorry,” Allen replied, recovering his grip on the strut and steering it back into position over the anchor. “What surprised me was that I was thinking the same thing myself—a nice lager, in fact."
"Stout to my mind: Bitter as a whore's love. But then there's ale, or even a pilsner: All the beers that make life worth living. I tell you, Tommy, it's a sad
state when a man can't toss back a pint now and again."
Allen knew that, just as he knew the Scot's “pint” was more likely half a liter than the pinch mug of fond racial memory. Just the same, the thought of a tall glass, glistening with beads of moisture against the dark amber fluid made his mouth water.
He'd only been in Jupe space for a year and was already homesick. There was no way he could cure that, though; his contract with JBI was for three more long years. Nor was there any way he could satisfy his thirst for those wonderful, heady, aromatic beers of memory. The damned petty administrators on the station forbade alcoholic beverages of any kind. “Too much risk of fire, fumes, and drunken workers,” the uncivilized officials proclaimed. This didn't give the damned tea-sipping Indians any grief, nor the coffee-swilling Americans, but what was a Canadian Irishman to do for comfort in such a God-forsaken environment?
Angus had been in the same boat, coming from a long line of whiskey-drinking, hard-fighting, tough Scots. “Born with a thirst and thinking to die unslaked a sin,” he'd declared on more than one occasion. Allen knew his desperation for an honest brew was probably greater than his own.
"Do you think we could get some?” he said absently. There was no chance of someone overhearing them on their private work channel. Radio was such a poor medium in Jupiter's static-filled environment that they used a tightly focused light link while they were working.
There was hardly a pause. “Be you thinking of smuggling, Tommy? There's a price too great to bear for such. Nor could we get such quantities to cool my soul. Unless, of course, you know something I do not."
"I'm afraid not. Besides, the cost of hauling a case of real beer from Earth, or even lifting that weak imitation Olympus from Mars, would be more a burden than my entire bank account could stand."
"Then there's no hope,” Angus wailed. “Unless . . ."
The strut finally shifted the last millimeter into position. Allen quickly shoved the anchor pin through the aligned holes of strut and brace and screwed it tight. Now they could get back to the station and lose these stinking work suits. “Unless what?"