Tag: seti

Grabby Aliens

Advanced aliens really are out there, and we have enough data to say roughly where they are in space and time, and when we will meet or see them. In our model, GCs are born according to a volume-based power law, and once born they simply expand at a constant speed relative to local materials. We show that for nontrivial powers this power law is a reasonable approximation to a more realistic model. This expansion speed and the 2 parameters of this power law are the only 3 parameters of our model, each of which can be estimated from data to within 4x. The hard-steps in Earth history literature helps to estimate the power, and our current date helps to estimate the power law timescale. Furthermore, the fact that we do not now see large alien-controlled volumes in our sky, even though they should control much of the universe volume now, gives us our last estimate, that aliens expand at > 50% of lightspeed. Given estimates of all 3 parameters, we have in this paper shown many model predictions regarding alien timing, spacing, appearance, and the durations until we see or meet them. And we have shown how optimism regarding humanity’s future is in conflict with optimism regarding SETI efforts. Being especially simple, our model is unlikely to be an exact representation of reality. So future research might explore more realistic variations. For example, one might more precisely account for the recent exponential expansion of the universe, and for deviations between a realistic appearance function and our power law approximation. Instead of being uniform across space, the GCs birth rate might be higher within galaxies, higher within larger galaxies, and follow their typical spatial correlations. A GC expansion might take a duration to bring its full effect to any one location, and the GC expansion speed might vary and depend on local geographies of resources and obstacles. Finally, GC subvolumes might sometimes stop expanding or die, either spontaneously or in response to local disturbances.

2023-04-11: A good summary of the argument

Galactic Settlement

The simulation depicts the expansion of a technological civilization through the Milky Way, created along lines previously described in the literature. What we are looking at is the transition between a Kardashev Type II civilization, and a Type III, which has spread throughout the galaxy. This might be a fast process considering the motions of stars themselves, which would overcome the inertia of slower growing settlements and boost expansion rates. Issues like starship capabilities and the lifetime of colonies come into play, but the striking thing is how fast galactic settlement occurs and how the motions of stars factor into the settlement wave. The parameters are everything, and they’re interesting:

  • Ships are launched no more frequently than every 100 ka;
  • Technology persists in a given settlement for 100 ma before dying out;
  • Ship range is 10 light years.
  • Ship speeds are 10 km/s; Voyager-class speeds.
  • The simulation covers 1 ga

Light sphere argument

If we’re to have an experience remotely like the human one, then we have to be relatively close to the beginning of time—since 100s of billions of years from now, the universe will likely be dominated by near-light-speed expanding spheres of intelligence, and a little upstart civilization like ours would no longer stand a chance. I.e., even though our existence is down to some lucky accidents, and even though those same accidents probably recur throughout the cosmos, we shouldn’t yet see any of the other accidents, since if we did see them, it would already be nearly too late for us.

if we want human-originated sentience to spread across the universe, then the sooner we get started the better! Just like Bill Gates in 1975, we should expect that there will soon be competitors out there. Indeed, there are likely competitors out there “already” (where “already” means, let’s say, in the rest frame of the cosmic microwave background)—it’s just that the light from them hasn’t yet reached us. So if we want to determine our own cosmic destiny, rather than having post-singularity extraterrestrials determine it for us, then it’s way past time to get our act together as a species. We might have only a few 100M more years to do so.

and here’s the preprint

SETI Limits

there should be at least 36 civilizations within our Galaxy: this is a lower limit, based on the assumption that the average life-time, L, of a communicating civilization is 100 years. If spread uniformly throughout the Galaxy this would imply that the nearest CETI is at most 17K light-years away, and most likely hosted by a low-mass M-dwarf star, far surpassing our ability to detect it for the foreseeable future

DNA SETI

Should We Search for Messages from Extraterrestrial Intelligences in Terrestrial Genomes? Compared to other methods of interstellar messaging, DNA-encoded messages could have the advantages of being auto- amplifying and blanketing across space and time (i.e., everywhere and persistent)

Dissolving The Fermi Paradox

relying on the Drake Equation is the same kind of error. We’re not interested in the average number of alien civilizations, we’re interested in the distribution of probability over number of alien civilizations. In particular, what is the probability of few-to-none?

SDO solve this with a “synthetic point estimate” model, where they choose random points from the distribution of possible estimates suggested by the research community, run the simulation a bunch of times, and see how often it returns different values.

A standard Drake Equation multiplying our best estimates for every parameter together yields a probability of less than 1 in a million billion billion billion that we’re alone in our galaxy – making such an observation pretty paradoxical. SDO’s own method, taking account parameter uncertainty into account, yields a probability of 33%.

10000x more sensitive Exolife test

The test uses a liquid-based technique known as capillary electrophoresis to separate a mixture of organic molecules into its components. It was designed specifically to analyze for amino acids, the structural building blocks of all life on Earth. The method is 10000x more sensitive than current methods employed by spacecraft like NASA’s Mars Curiosity rover.

Is Physical Law an Alien Intelligence?

Or to take this a step further, perhaps the behavior of normal cosmic matter that we attribute to dark matter is brought on by something else altogether: a living state that manipulates luminous matter for its own purposes. Consider that at present we have neither identified the dark-matter particles nor come up with a compelling alternative to our laws of physics that would account for the behavior of galaxies and clusters of galaxies. Would an explanation in terms of life be any less plausible than a failure of established laws?