Archive for the 'Extraterrestrial Life' Category

Alien Civilizations VII: Black Hole Power

Some of you might remember my posts about the possible existence of alien intelligence. Executive summary:

Alien civilizations will tend to expand rapidly over intergalactic distances, eventually sweeping over our solar system. Such intelligence will harvest any and all resources it can for its own use, and thus be harvesting the solar system. Thus, alien civilization, if it existed, would be blatantly obvious. It is not, therefore, alien civilizations are unlikely to exist.

Now with my recent realization about black hole power, I have come to refine my arguments about alien intelligence. 1) Since a black hole power plant would be, in theory, a 100% efficient matter-to-energy converter, it will be the preferred method for alien intelligences to use. 2) Obviously, matter to fuel the black holes will still be necessary, thus alien intelligence will likely still harvest as much matter as they can. 3) Black holes are much more ideal for energy storage than antimatter, since literally nothing can escape them (except for Hawking Radiation as described earlier).

So, my former conclusion still holds.

But I did realize something interesting. Let’s say there was an alien intelligence doing this. They are expanding at slower-than-light speeds across intergalactic space, basically making them look like an expanding sphere of darkness where they have enclosed stars with Dyson Swarms (or perhaps collapsed them into black holes). This is basically what we see in the universe today. Huge intergalactic voids with “nothing” in them. And between these voids are thin streams of galaxies.

I made this argument before, but discounted it because Dyson Swarms would still allow waste heat to escape and thus be detectable over intergalactic distances (or, at least, a whole galaxy of infrared sources would be detectable).

The thing is, black hole power plants wouldn’t give off this waste heat. At least in theory. A whole galaxy of black holes would radiate almost no power, and thus be undetectable across the universe, except for their gravity.

Which would be even closer to what we see today: Dark Matter, Intergalactic Voids.

Basically, my idea is, we happened to evolve at a point in history where a number of civilizations have arisen in the universe and are just starting to bump into each other in intergalactic space. Our galaxy hasn’t been reached yet, but it will soon.

We can even apply the Anthropic Argument here. Basically, why are there no alien civilizations apparently around? Because they haven’t reached us yet. If they did, we wouldn’t have evolved to ask the question.

Anyway, despite all this rampant speculation, it is important to review Sagan’s quote at the top of the page: “We should not be afraid to speculate. But we should be careful to distinguish speculation from fact.” No matter what I may type here, it is ONLY empirical evidence that will decide on way or another. Speculation may have its place, but speculation must always give way to scientific evidence.

I don’t know if I’m right, but it is interesting to think about. It’s a jumping off point, not an end in itself.

Potential Ocean Planet Found!

A few days ago, it was announced that the star GJ 1214 has a planet orbiting it, dubbed GJ 1214b. The massively interestesting part is they were able to measure this planet’s diameter as it transited across its star, and measure its mass via its star’s wobble like you do. Anyway, using this they calculated the planet’s density, which is estimated to be around only 1800 kg/m^3.

For comparison, Earth is around 5500 kg/m^3, while water is about 1000 kg/m^3. In other words this planet is mostly made of liquid water! At least that’s the most likely answer. The next most likely liquids (like liquid carbon dioxide) boil at a much lower temperature than what the planet is estimated be at (between 250 – 550 degrees F).

Now, the more astute among may notice that the planet is also above the boiling point of water. The thing is, as pressure goes up, so does the boiling point (the reverse is also true, which is why at higher elevations the boiling point drops and it take longer to cook food). For example, at 100 atmospheres, the boiling point of water is around 520 degrees F. So it’s possible for there to be a huge global ocean, as long as a sufficiently dense atmosphere is also there. That sounds like a pretty big conjecture, but the density of the planet is known, meaning there must be some sort of atmosphere dense enough to hold it in. My bet is that its mostly water vapor (most astronomers are saying its likely hydrogen and helium, but at the same time there’s substantial loss to space due to its proximity to the star, and there’s really no way for the planet to make more hydrogen and helium to replenish it).

So, lets explore this world together! First, based on its density, scientists calculate that it composed of roughly 25% rock and 75% water. Obviously, the rock will be in the core since rock is denser than water and will sink towards the center. The planet’s diameter is estimated to be 34,000 km across, so its core, taking up about one-fourth the volume, would be around 21,000 kilomteters across. On top of that is water, an ocean 6500 km deep. That’s roughly 1000 times as deep as Earth’s oceans!

Now some interesting things happen when you consider how that all fits together. As I said before the atmosphere is likely composed of water vapor. Water vapor is a greenhouse gas, and will cause the temperature to rise, causing more water to evaporate, thus increasing the greenhouse effect. This will likely continue until some sort of equilibrium is reached, where the influx of heat from the star is the same as the amount radiated away. This might be beyond the point where water goes supercritical (that is,  the line between liquid and gas vanishes and they sort ‘blend into’ each other). That means that the water vapor atmosphere likely just gets denser and denser until it reaches the density of water, at which point it can’t compress anymore.

Even more interesting is what happens down in the depths of this massive ocean. There, the pressure become high enough that the water will become solid, making an exotic form of ice known as Ice VII. This is not like ordinary ice. This is hot ice, denser than water, and probably forms a layer around the rocky core.

In short, this planet most likely looks like a miniature Jovian planet, with water as the gas present instead of hydrogen.

So what about the most obvious question: if there water, what about life? I don’t know. With supercritical water I don’t think that organic structures could even form. But, if the atmosphere really is made of hydrogen (which isn’t a greehouse gas) the temperature would stay much lower, low enough for water to retain all its life-assisting properties. Anyway, here’s a nice graphic (I like graphics) to help illustrate what this planet is like:

 

Alien Civilizations VI: Additional Thought

Thinking over my hypothesis about why there are no extraterrestrial civilizations around, at least none within several hundred million light-years, I realized a small loophole. I assumed that the alien civilization would be trying to survive as long as possible. But what if there isn’t that much longer to live? That is, what if the universe won’t be capable of supporting life or intelligence of any kind at some point in the future?

It may sound strange but there is a hypothesis being kicked around called the Big Rip. Basically, the universe is expanding, and it is accelerating. So, what if the acceleration itself is increasing as well? In technical kinematic terms, the jerk is non-zero (yes, that really is the term for change of acceleration. Change in position is velocity. Change in velocity is acceleration. Change in acceleration is called jerk. I didn’t just make that up. Jerk). Anyway, it postulates that if this is the case eventually galaxies and solar systems, all the way down to planets, life-forms, even atoms will get ripped apart by the rushing expansion of space. If true, the scientists that developed this concept estimate that around 50 billion years from now this would happen.

50 billion years is a long time, but is actually quite small compared to the length of time I estimated an advanced civilization could survive. In short, there may be alien civilizations out there that don’t convert the entire universe into energy stores because they just don’t need to. A single star would supply all their energy needs until the end. They might even encourage the development of other intelligent species since, hey, we’re all doomed anyway, and there’s more than enough room in the meantime. They might as well have some company.

The Big Rip is still just a hypothesis. There’s no evidence that it’s actually going to happen. But if we do ever discover alien civilizations, it might be a big tip-off that maybe the universe doesn’t have as long to go as we think it does (though it would do to confirm it independently, as they probably would have).

Next Post: Black Hole Power

Alien Civilizations V: Paradox

We should expect alien civilizations, if they exist, to quickly expand and colonize the galaxy. If they exist, they should already be here in our own solar system, mining the Sun, harnessing its entire output via a giant arrangement of solar collectors enclosing the sun. Their existence would be blatantly obvious. All we would have to do is look up and see, with our naked eyes, enormous engineering constructs in our solar system.

These constructs, however, do not exist. Furthermore, we can be certain they also do not exist around any other stars that we can see because, well, we can see the stars. If our solar system were spared from this fate for some reason, our nighttime sky would still be completely black.

The implication is obvious. There are no alien civilizations in our solar system, so there aren’t any anywhere. At least, there are none close enough in time and space to have made it here yet. For example, if an alien civilization developed one billion years ago in a galaxy two billion light-years away, then they would not have been able to have spread here yet. The laws of physics cannot be broken, not even by a super-advanced civilization.

But assuming they do still exist, why haven’t they done this? I honestly doubt that they would be hiding. If I were a super advanced civilization going about the universe this way, I probably wouldn’t bother hiding. What would be the point? Any developing civilization would probably eventually end up competing for the same resources. Indeed, I might be inclined to wipe them out before they could be a threat in order to secure my own survival.

And that raises another excellent point. If an alien civilization did evolve far in the past and colonize the galaxy, why are we still here? The fewer civilizations that have access to resources, the longer each civilization can survive. Plus, by constructing a Dyson swarm, they might even have deconstructed Earth for materials. Similar to the previous question: why is Earth still here? Not that that’s necessary to use Earth for materials. There’s likely enough material in the asteroid belt to make a Dyson swarm, but since there are more materials laying around, you might as well use them too (plus if you remove the planets and are left with only the swarm, you no longer have large masses gravitationally tugging on your collectors causing them to drift out of their orbits).

Then again, maybe they did exist, but died out before they had a chance to colonize the galaxy. Maybe there have been many civilizations which have all died out. This paints a rather unfortunate future for ourselves if true. They might even have sent precursory robotic probes throughout the galaxy as stated in Part III, but then died out before continuing. If so, there might still be alien base orbiting the Sun, or an alien base set up on some asteroid, waiting to someday be occupied by beings that no longer exist.

There is another mystery that galaxy-colonizing aliens seem, at first glance, to solve: dark matter. There is a large about of matter in the universe which we can detect gravitationally, but which does not shine or absorb light, rendering it, effectively, invisible. Maybe there really is a galaxy-spanning civilization harvesting the starlight of most, but not all, stars, and the ones we see are the small percentage.

To be honest, I don’t think that is what is really going on. If that were the case, we should still be able to detect their waste heat. There would be a very large number of anomalous heat sources crowding the sky, outnumbering visible stars by 9-to-1, and we would be left with the paradox of why such a civilization would choose 90% of the stars in the galaxy and leave the other 10% alone.

But that line of logic leads to what could be called a prediction of my hypothesis: find a galaxy, or cluster of galaxies, which are unusually dim, and/or radiating lots of infrared and radio light, but not visible or higher frequency light. Freeman Dyson essentially proposed the same thing-looking for anomalous heat sources in the sky-but predicted only point sources within our own galaxy. Here, I am predicting extended heat sources, perhaps actually covering significant portions of the sky, at hundreds of millions of light-years’ distance.

In the end, I think that the most likely state of affairs is that there are no extraterrestrial civilizations in our galaxy, neighboring galaxies, or within several hundred million light-years. This is pretty depressing thought, being alone. But it’s also one of great opportunity: we made it! We’re the first! The vast resources of the universe are ours for the taking! We have won the comic lottery, so to speak. At least, we will if we are able to band together, act in a unified fashion in order to ensure our own survival, instead of spending most of our resources finding new ways of killing each other.

But to be honest, I think we do have what it takes. In 1950, the idea that human civilization would last until the year 2000 was uncertain. There were many who thought the odds were the human race was on the brink of extinction. But today, the idea of the human race surviving to 2050, 2100, 2200, and so on seems much more believable. Global superpowers have learned, it seems, that working together is much more productive and desirable for all of the human species. In the words of Carl Sagan, who had fiercely argued against nuclear proliferation, “perhaps we have, after all, chosen life.”

So what about all other current efforts to find extraterrestrial life, namely SETI? SETI is searching for extraterrestrial radio broadcasts, perhaps beamed to us deliberately or “leaked” accidentally. So far–obviously–they have found nothing. Under my hypothesis, this result isn’t very surprising. They haven’t been found because there’s no one there. If they really wanted to relay information to us it would likely be through a probe already stationed in our own solar system, one which would have been there throughout all of human existence.

But does that mean I think that such a search is a waste of time? Absolutely not. Science is, after all, grounded in observation and experiment, not theorizing. My hypothesis could be entirely wrong, and could very well be disproved by SETI by discovering a single instance of extraterrestrial intelligence. I whole-heartedly support their efforts and, given the circumstances, really wouldn’t mind being proven wrong. If my hypothesis is right, we are the first sentient species to colonize the galaxy, and if I’m wrong, we have other intelligent species in the universe. Either way, I win.

Next Chapter: Additional Thought

Alien Civilizations IV: Survival

An alien civilization, existing for billions of years, will swiftly colonize every star in the galaxy shortly after developing (that is, swiftly compared to the amount of time that has already progressed). If an alien civilization has formed once, then its artifacts should already be here in our solar system.

Next Chapter: Paradox

But is that all that they will do? Litter space with probes and garbage? But let’s try to consider what an alien species would really do during billions of years of time. Let us assume one thing: that an alien species, having evolved and survived the evolutionary process, will take steps to maintain and maximize their own survival.

In order to facilitate this, let’s imagine that it is us who are trying to maximize our survival. What can we do? How to we make it possible for our civilization to survive for the longest possible amount of time. Living forever is obviously impossible, but with a mindset for conservation, our civilization could probably survive far beyond the death of the sun, far beyond the end of the flickering out all the stars, even up to the point where matter itself will decay into subatomic particles.

How? The two deciding factors are how many resources we have, and how fast we use up those resources. Far in the future, the only real resource that will matter is energy. From a physical standpoint, you can keep recycling the same matter over and over, so long as you continually input energy to combat entropy. For example, you can burn gasoline to run an engine, then take all the exhaust and reverse the chemical reaction and literally turn smog back into gasoline. All that’s needed for the last part is an energy source and the know-how to do it.

Now, far in the future, we’ll likely be uploads living in virtual space. We likely won’t be using gasoline, and our impact on physical reality will be significantly reduced. All we’ll really need are computer systems and a power source, and computer hardware is extremely durable. Likely computers in the future, just like computers today, will have very few, if any, moving parts. Once the virtual space servers and systems are all set up, they will likely require very little maintenance for centuries.

All that leaves is energy. Our civilization’s survival becomes dependent on how much energy we have, and how fast we use it. To put some numbers to it, let’s assume that human civilization consists of ten billion uploaded people, who each consume, on average, on thousand watts. Power usage is clearly ten trillion watts, or ten terawatts, around 70% of humanity’s current power usage.

Next, we want to expand our energy reserve as much as possible. The most energetic object relatively close to us is the Sun. The Sun’s power output is some four hundred trillion trillion watts, or forty trillion times greater than our future needs. We could use only a small portion of that power, and just let the rest radiate away into space much as what happens today, or we could capture the entire solar output by enclosing the Sun with a Dyson swarm, and save it for later. Antimatter would do nicely for this. The Sun will only last the next five billion years or so. By using only a tiny fraction of its output and saving the rest, we could survive on its power output for forty trillion times longer than the rest of its lifetime, or 2 x 1023 years. This is from a single star.

Of course, the Sun is actually a pretty poor producer of energy per unit mass. It might be useful to actually mine hydrogen and helium from the surface of the Sun and burn it in our own fusion reactors. We can continue fusing the resulting nucleons into more massive elements (until you hit iron, which takes energy to fuse), and accounting for inefficiencies in the process, let’s estimate that we can tap fully 1% of the total mass-energy of the Sun. The total mass of the Sun in 1.989 x 1030 kg, so we will have on hand 1.989 x 1028 kg of energy, or 1.788 x 1045 J. At ten terawatts, our civilization could survive 1.788 x 1032 seconds, or about 5.676 x 1024 years.

This is an enormously long time. It is currently estimated that star formation won’t last much more than one hundred trillion (1015) years. But even after five trillion trillion years, the universe will still be quite habitable. Matter and energy will still exist, and if we take further steps, we can increase our civilization’s lifetime many orders of magnitude further.

So far, we have only exploited the resources of a single star. What if we expand the area from which we are gathering energy to include the entire galaxy? It is currently estimated that the Milky Way masses roughly 580 billion solar masses. By using all of that material, we would extend our survival by a factor of 580 billion, or 3.29 x 1036 years. We would do this by constructing Dyson swarms around every star in the galaxy, and gathering all extra interstellar material not already in stars. It’s quite a task but almost trivial considering we have hundreds of billions of years to figure out how to do it. And actually, it probably wouldn’t be all that hard. By sending out von Neumann probes, we would very quickly colonize the galaxy and begin autonomously constructing these Dyson swarms. All the stars in the galaxy would become covered by these swarms more or less simultaneously, and almost within the blink of an eye: a few million years, tops.

We could then go about colonizing and consuming other galaxies as well, but by now you should see the point. The logical consequence of wanting to survive for the longest possible time leads to having a large portion of the visible universe converted to, essentially, power generators and battery packs. And the sooner this process is started, the more energy we will have to live on. The Sun, and the galaxy, is blazing away far far more power than we actually need, and it’s being wasted by going out into empty space. Every year that we spend not mining the galaxy for energy costs us literally billions of trillions of years of time in the far future.

Of course, when we combine this plan with the possibility of alien intelligent the obvious question arises: why hasn’t this already happened? Why don’t we look up in the sky and see that the Earth is orbiting inside a giant opaque sphere? If aliens exist, and if they care about their own survival, why haven’t they figured this out? Everything that I have described requires a number of breakthroughs (interstellar travel, intelligent autonomous robotic probes, interplanetary-scale mega-construction, the social and political will to commit to projects lasting many millions of millennia, etc.), but none of them violate the laws of physics. It’s merely pushing survival instinct and technical know-how to their logical extreme. Any alien civilization that has evolved in the past several billion years will have both. So where are they?

Next Chapter: Paradox

Alien Civilizations III: Travel

An alien civilization is likely to have developed billions of years ago. They would have swiftly progressed through the technological invention stage, and long ago reached the point where they could do all the things they wanted, bound only by the laws of physics (they couldn’t, for example, create matter and energy out of nothing).

So what would they do for all those billions of years? Most likely, they’ll begin to spread out. Staying on one planet, or even in one planetary system, is more or less suicide. There are innumerable catastrophies that can befall such a multi-planet but single-system species: supernovae, gamma ray bursts, war, and eventually the death of their star itself. A species that has been able to survive the evolutionary process would have survival instincts and desires hard-wired into their brains (or whatever thinking organ they have… if they have organs…). And, they are very very smart, even smarter than us. It seems overwhelmingly likely that they would take to the stars.

Interstellar travel is slow and it is hard. Even at the speed of light–the absolute fastest it is possible to go–travel across the galaxy takes tens of thousands of years. And getting even close to that speed takes enormous amounts of energy.

But wait…tens of thousands of years? The species we’re dealing with is billions of years old. From that perspective, interstellar travel is actually pretty fast. In fact, even using concievable methods of starship propulsion, the time to cross the entire galaxy is measured in only millions of years. Here is a table detailing various engine types both real and theoretical (though all physcially possible) and their performances:

 

H2 – O2

Ion

VASIMR

H3–D Fusion

Antimatter

Exhaust Velocity (km/s)

4.5

88

294

7,480

100,000

Max. Speed (km/s)*

20**

183

610

15,500

104,000***

Time to Alpha Centauri (4.36 ly)

65,350 y

7,140 y

2,140 y

84.3 y

12.6 y

100 ly

1.50 mil y

164,000 y

49,100 y

1,930 y

288 y

1000 ly

150 mil y

1.64 mil y

491,000 y

19,300 y

2,880 y

Galactic Core (26,000 ly)

390 mil y

42.6 mil y

12.8 mil y

503,000 y

74,900 y

Across Galaxy (100,000 ly)

1.50 bil y

164 mil y

49.1 mil y

1.93 mil y

288,000 y

Andromeda Galaxy (2,400,000 ly)

36.0 bil y

3.93 bil y

1.18 bil y

46.4 mil y

6.92 mil y

*Max. Speed is figured by assuming a staged rocket with an overall mass ratio of 64, and assuming the probe will stop at its destination. If the mission is just a fly-by, the maximum speed would be twice as high.

**Because hydrogen-oxygen rockets tend to be very slow, any probe would likely also utilize gravitational boosts by flying near the outer planets, increasing its speed while not using any propellant. Other engines could also utilize this, but the amount added is very small compared to the overall speed.

***It is likely impossible to have an staged antimatter rocket with a mass ratio of 64, since antimatter tends to annihilate when it touches normal matter. An antimatter fuel tank would have to be arranged to keep the antimatter suspended completely away from the rest of the normal-matter rocket This figure is based on a mass ratio of 8 (that is, three stages, each consisting of a mass ratio of 2).

As you can see, even today’s hydrogen-oxygen rocket technology is more than sufficient for crossing (and thus colonizing) the galaxy in the given. Keeping a ship working for a billion years is definitely a challenge, but if aliens have billions of years to work on the problem, they’d probably be using antimatter rockets and know how to keep them operational for the several hundred thousand years necessary.

But why would they come here? Our solar system is just one in two hundred billion. There must be many interesting locations to explore. The odds that they would choose ours are literally billions to one.

But it is more useful to see the galaxy from the alien’s perspective (which is actually not very different from our own). We live in one tiny patch of space and want to know as much about the rest of the galaxy as possible. Sending probes to stars one at a time is very inefficient. The mathematician John von Neumann showed that by using self-replicating robotic probes, one can create a vast number of interstellar probes for very little cost (you only have to pay for the first one). These probes would utilize the resources found in other solar systems to make copies of themselves, then send the copies off to the next star system. The aliens wouldn’t just colonize a few stars, they would colonize all the stars.

More likely, it would be desirable to make all the probes in your own star system using the resources available then launch them all at once. This is better because A) you avoid two robotic probes heading to the same star system B) you avoid the problem of a probe coming upon a system that has no resources and so can’t make a copy of itself and C) you can better control the self-replication process, avoid any accidents.

Such robots would then explore their respective targets and likely continue observing over a period of millions of years (assuming advanced self-repair capabilities). Perhaps they might even set up colonies if any of their creators wished to relocate there, or even begin terraforming any suitable planets.

The implication is obvious, if aliens have evolved at some point, they’re probes should already be here in our solar system. We have never found such alien artifacts, but the solar system is a largely unexplored place. The most likely place to find such artifacts are in a place where resources are plentiful and easy to get at. That is not the Earth, or the Moon, or any planet at all. They would likely reside in the asteroid belt, where there are vast resources, out of deep gravity wells, and close enough to the sun to provide a constant power source. The Kuiper Belt, farther out, has even more resources, and the probes might use on-board fusion plants for power instead of the Sun.

Maybe they’re out there right now. If so, there’s no use trying to signal them. Assuming they’re still active, they know all about us and aren’t talking anyway. There are hundreds of millions of asteroids out there and the only way to find them, perhaps, would be to send out our own von Neumann probes to scour the solar system.

Next Chapter: Survival

Alien Civilizations II: Time

The first notion that we need to contend with is the enormous span of time that has come before human civilization. Human civilization has been around, at most, for around 10,000 years. The human species, homo sapiens, has been around for around 200,000 years. These are very long periods of time, but are insignificant when compared to the fact that the Earth itself is 4.6 billion years old. The universe is about three times older, clocking 13.7 billion years so far.

For all of Earth’s existence, the human species have only been walking around on it for 0.004% of the time. Yet in that tiny tiny sliver of time, be have ascended from mere animals into a global technological civilization. In fact the vast majority of this progress has only taken place within the past few centuries.

It is reasonable to believe alien civilizations will follow a similar pattern. Very soon after evolving, an alien civilization will develop technology and likely head for the stars. The thing to remember is that the point in time when this alien civilization evolves is essentially random. If you pick a random point anywhere during the history of the universe, you will likely end up picking a point billions of years in the past. In fact, the odds are greater than 99% that you will pick a point further than 100 million years in the past. If aliens have evolved on some other planet at some point, they have already vastly surpassed our capabilities, assuming they don’t destroy themselves in the process.

Next Chapter: Travel