Communion Of Dreams


“You’re oversharing again, Earth.”

Seth Shostak, on the topic of how to introduce ourselves to our neighbors:

A better approach is to note that the nearest intelligent extraterrestrials are likely to be at least dozens of light-years away. Even assuming that active SETI provokes a reply, it won’t be breezy conversation. Simple back-and-forth exchanges would take decades. This suggests that we should abandon the “greeting card” format of previous signaling schemes, and offer the aliens Big Data.

For example, we could transmit the contents of the Internet. Such a large corpus — with its text, pictures, videos and sounds — would allow clever extraterrestrials to decipher much about our society, and even formulate questions that could be answered with the material in hand.

 

While I still agree with Stephen Hawking on the idea of ‘active SETI’, I think that there’s merit in the idea of exposing other nearby civilizations to what we’re really like, warts and all. Because as soon as they decoded our transmissions well enough to understand the comments section of pretty much any major site on the web, they’d either completely wall off our solar system* and post warnings around it or just trigger our sun to go supernova. Either way, we’d never know what happened, and the rest of the galaxy would be safe …

 

Jim Downey
*gee, that’d make an interesting premise for a SF novel, doncha think?

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Location, location, location.

It really does seem to be a pretty universal law:

On the role of GRBs on life extinction in the Universe

As a copious source of gamma-rays, a nearby Galactic Gamma-Ray Burst (GRB) can be a threat to life. Using recent determinations of the rate of GRBs, their luminosity function and properties of their host galaxies, we estimate the probability that a life-threatening (lethal) GRB would take place. Amongst the different kinds of GRBs, long ones are most dangerous. There is a very good chance (but no certainty) that at least one lethal GRB took place during the past 5 Gyr close enough to Earth as to significantly damage life. There is a 50% chance that such a lethal GRB took place during the last 500 Myr causing one of the major mass extinction events. Assuming that a similar level of radiation would be lethal to life on other exoplanets hosting life, we explore the potential effects of GRBs to life elsewhere in the Galaxy and the Universe.

 

What that means is summed up in this article. Here’s the conclusion:

Astronomers have long known that the Earth occupies a unique position in the solar system that allows life to flourish. This idea of a habitable zone now allows them to focus search for exoplanets that might also have conditions that are right for life. Now they can take this further by excluding inhospitable regions of the galaxy, and searching only those stars and galaxies that exist in the universe’s habitable zones.

 

Of course, that’s just for life as we know it

 

Jim Downey

 



“It’s a way to frame the problem,”

As something of a follow up to my last post, there’s a great little item about the development of the Drake equation over on National Geographic. Here’s a good passage:

It’s this kind of guesswork that tends to inflame the Drake equation’s critics, those who complain that the equation isn’t predictive, is too open-ended, and doesn’t provide any answers. But “predictive” isn’t really what Drake ever intended.

“It’s a way to frame the problem,” says MIT astrophysicist Sara Seager, about the equation. “In science, you always need an equation—but this isn’t one you’re going to solve. It just helps you dissect everything.”

Definitely worth reading, as well as thinking about.

Jim Downey



30 billion Earths.

How many Earth-like planets are there in our galaxy? Ones which are reasonably like ours, in terms of size, density, and location relative to their sun’s ‘habitable zone’? That’s one of the basic components of the Drake Equation, and until fairly recently all estimates were little more than speculation.

Enter Kepler:

Expanding our view from Kepler’s corner of the galaxy to show more of the Milky Way, the sky fills with billions of potentially life-bearing worlds. If we showed them all, the sky would be a mass of green. So now the green dots illustrate stars that might host such planets, visible with a good pair of binoculars on a dark night here on Earth.

From this perspective, the chances that we’re alone in the cosmos seem very slim, indeed.

The final answer? 15 – 30 billion Earth-like planets.

Of course, that doesn’t include the rest of the Drake equation values. Such as: what percentage of planets which could potentially develop life actually do so? Then what percentage of those planets develop intelligent, technologically sophisticated life? Then what percentage of such intelligent species develop interstellar communication capabilities? Then how long will such a civilization survive, out of the billions of years of history?

The last time I played with the numbers, the best guess from Phil Plait was that there were some 2.5 billion potentially habitable planets. Kepler indicates that number was too conservative, by something on the order of a factor of 10. Running the rest of the equation is largely just an experiment in gut feelings (since we don’t yet have any real data), but what is impressive is that at each stage as solid data has become available, we’ve had to adjust our “best guesstimate” numbers *upwards*. Meaning that the the total number of technologically sophisticated civilizations capable of interstellar communications out there at this point in time also goes up.

From Chapter 4 of Communion of Dreams:

“But in any event, as Arthur Bailey said this morning ‘where are they?’ Where are the aliens? That’s what’s bothering me.”

Where, indeed? I came up with my own answer, explained in Communion.

But I wonder what the real answer will be.

Jim Downey



Is there anybody out there?*

From the opening pages of Communion of Dreams:

Jon sat there for a moment, trying to digest what Seth said. According to what pretty much everyone thought, it wasn’t possible. SETI, OSETI, META and BETA had pretty much settled that question for most scientists decades ago, and twenty years of settlement efforts throughout the solar system hadn’t changed anyone’s mind. Even with the Advanced Survey Array out at Titan Prime searching nearby systems for good settlement prospects, there had never been an indication that there was an intelligent, technologically advanced race anywhere within earshot.

It’s one of the very basic questions of space science: are we (sentient beings) unique? Rare? Common? There are a lot of ways to think about it, and here’s a nice piece on NPR discussing some of the relevant parts of the question and what we’re doing about it.  An excerpt:

So, to address the first part of the question we must find out how unique the Earth is. We then should figure out how unique life, and humans, are. Fortunately, thanks to NASA’s Kepler mission, we are making huge progress in the first part of the answer. A key finding is that the majority of stars (around 70 percent) have at least one planet orbiting around them. Based on the data so far (2,740 planet candidates and 115 confirmations), Kepler scientists estimate that some 17 percent of these are Earth-size, meaning with similar mass and rocky composition as the Earth, and possibly close enough to their parent star that water, if present, could be in its liquid state.

More good news arrived on this front earlier this month as NASA authorized the construction of Kepler’s successor, TESS (for Transit Exoplanet Survey Satellite). With launch scheduled for 2017, TESS will survey a much wider area of the sky than Kepler, while focusing mostly on stars that are closer. This way, it will use spectroscopy to resolve at least part of the atmospheric composition of the exoplanets. The goal is to find telling signs of life-related compounds such as ozone, water, carbon dioxide and, if we’re really lucky, even chlorophyll. Successful detection would be very exciting, as it’d point to what optimists expect, a few fairly close Earth-like planets with metabolizing beings.

I hope I live long enough that science is able to make a definitive affirmation of life, then intelligent life, outside our own planet.

Until then, well, there’s science fiction.

 

Jim Downey

*Seemed appropriate.



Waiting for it.

They say Isaac will be paying us a visit.

* * * * * * *

I’ve previously talked about the Drake Equation, and how new information from a host of sources is changing the calculus of expectation — expectation of what is waiting for us out in the universe.

Well, via Wired and BoingBoing, there’s a new fun graphical tool now available to explore the Drake Equation. Check it out:

Drake equation: How many alien civilizations exist?

* * * * * * *

From Chapter 4 of Communion of Dreams:

“But in any event, as Arthur Bailey said this morning ‘where are they?’ Where are the aliens? That’s what’s bothering me.”

* * * * * * *

They say Isaac will be paying us a visit.

I’m in a somewhat weird headspace right now. Maybe that’s the reason for it. We’re suffering such a drought that it seems almost surreal that there may be rain this weekend. And not just a little rain: current forecast models say between two and six inches, most of it in about a 24 hour period. That won’t break the drought, but it would cause flash floods.

Like I said, surreal.

Similarly, I’ve been thinking — and thinking hard — about the Kickstarter for St. Cybi’s Well. But all my thoughts seem to be random, chaotic. Nothing will quite ‘gel’, to use another reference from Communion of Dreams.

But when it does, I think there will be a flood.

Jim Downey