Proxima Centauri has a Earth-like planet | Hacker News Reader

Proxima Centauri has a Earth-like planet

phys.org

75 pointslrondanini40 comments

I appreciate it's 100% speculative, as we are stuck with a sample set of only one, but I'm increasingly of the belief that we're rare (as opposed to first or fucked [1]).

Heavily swayed by a recent reading of Nick Lane's excellent book on Mitochondria[2].

The fact that even our nearest neighbour probably has an earth-like planet is, from this angle, a bit depressing.

[1] http://waitbutwhy.com/2014/05/fermi-paradox.html

[2] https://en.wikipedia.org/wiki/Power,_Sex,_Suicide

The Percolation Theory reasons that Earth might linger in an uninteresting part of the Milky Way: its galactic backwaters. See:

* [1998] http://www.geoffreylandis.com/percolation.htp

* [2014] https://arxiv.org/abs/1404.0204

That Landis paper is great, thanks.

You may find the "dark forest hypothesis" that's put forward in the Three Body Problem/Dark Forest series bu Liu Cixin an interesting possible solution for the Fermi Paradise.

Interestingly, a planet on Proxima Centauri is a major plot point in the novels.

Yup, I've read the first two of this series, and it's an interesting proposition, but also pretty depressing.

Nation states and / or races are a hopeful and cheery counter example... or in for a hard time.

I don't know. Fermi paradox has never bothered me too badly. Between possible great filters (behind and/or ahead of us), the time and distance involved in species discovery and travel, and the fact we're still apparently pretty early in the universe's lifespan ... it seems reasonable to me that we may be some combination of rare and early. So, Group I seems reasonable.

One potential "great filter" always stood out as likely to me, even if all the other leaps before we came along had been made:

That filter is developing the combination of (i) self-aware intelligence to a degree that you are capable of deep layers of abstraction, (ii) the physical ability to adeptly physically build complex creations, (iii) an inclination toward social living that encourages cooperation. Other relatively high intelligences have evolved here on earth: octopuses, dolphins, elephants, etc. But it's hard to imagine any of them being physically capable of dramatically modifying their environment and building complex, useful creations. And we mammalian humans, dolphins and elephants are all social and cooperative to some degree, but octopuses don't seem to be. The combination of these three occurrences is extremely powerful, but may also be extremely rare. And it's difficult to imagine a space-faring civilization that wouldn't need all 3.

And Group 2 seems reasonable too. In particular, it's interesting to consider that while we currently hold an expansionist mindset because expansion has driven the course of our civilization, this may be a temporary thing. It makes sense when competing locally with enemies (other tribes, cities, nations, empires, etc) that are very similar to yourself. And we believe that survival and expansion go hand in hand. But it may well be the case that intelligent species generally discover that survival is maximized when not expanding aggressively, beyond some point, and when conserving resources. Hiding themselves so as to minimize the risk of contact with other alien species may go hand in hand with that as well.

So, between seemingly plausible filters in both Group 1 and Group 2 explanations, I think it's reasonable to entertain the possibility that it'll be a long time before we meet another alien civilization, if we ever do.

I think it makes sense for an intelligent civilization not to expand, if you consider the problem of synchronizing over vast interstellar distances. If it takes years to exchange messages and resources back and forth between two colonies, it will be slow and costly to keep them on the same page. That means they will likely evolve independently and may become competitors.

In other words, colonies lacking resources inside the expansion wave would start attacking their own neighbours, and colonies at the periphery may decide to expand inward, because even though other colonies' resources are harder to acquire, they are already processed/terraformed and therefore more useful. So you don't expand, not necessarily to hide, but to avoid creating enemies in close proximity to yourself, because you can't control your own offspring except at a tremendous cost.

Of course, even so, it seems strange that no civilization would ever make this mistake. Perhaps those that do are far away, or the propensity of colonies to eventually expand inward slows down the expansion.

>In other words, colonies lacking resources inside the expansion wave would start attacking their own neighbours,

This could be possible if interstellar travel was very, very, very easy. But in all likelihood the last place you're going to want to find resources is on a tiny speck of rock 20 lightyears away.

Well, the basic idea is that some inhabitants of colony A may figure that if they remain on A, they can only expect to get 100 resource units, but if they move to B, which is weaker, they may be able to acquire 1,000 resources units instead. They wouldn't bring back resources from B to A, they would just do a hostile takeover so that they can live like kings.

True hive-mind intelligences may not face that problem, though.

A hive mind would face tremendous costs and very small returns. If you think of a human brain as a hive mind made out of neurons, which isn't an unfair way to describe it, a hive mind split on two planets would be like two brain hemispheres being light years apart. They can't help each other without unacceptable delays, so they would both have to be almost completely independent to function properly. They couldn't make each other very much stronger.

Furthermore, synchronization overhead scales with distance: you may be part of a hive mind, but if it takes ten years to exchange a message with the rest of the hive, you have to act independently during these ten years. This means the hive's "goals" must be replicated on each colony well enough to make sure they can't drift too far in that time. This is not cheap: for example, a lot of innovative technologies would have to be stifled while the whole hive assesses the risks they pose to its own integrity. Independent colonies, on the other hand, would just plow forward.

Delays in research and coordination, yes, but not the threat of internal competition or warfare, at least.

I imagine a hive mind would first send scouts to potential habitats, wait to gain enough information about a world from them, and then dispatch a colonizing group with fixed orders and some leeway in local operating parameters.

After that they'll coordinate just like all species will have to, within the confines of Physics.

If a colony cannot adapt to a planet while remaining within the hive's goals, then I guess it simply withers happily, till new scouts deem the world worth another try.

That could actually turn out to be an efficient way of spreading across the galaxy..

Possibly. On the other hand, the delays in research and coordination may be so large that they basically negate the advantages of being united. An expanding orb of viciously competitive societies would probably make them pretty damn efficient at deception, murder and hostile takeover. A hive mind that has never had to harden itself against what's basically an expanding sphere of vicious viruses may be easy prey that gets utterly annihilated.

To put it in another way, I think an expanding hive mind needs to develop an immune system of sorts if it is to stand up against nimbler (virus-like) societies, but it's hard to see how it could succeed effectively without extended exposure to the latter.

So I feel there's a kind of catch-22 going on: if we expand without extensive synchronization, we create competitors out of our own offspring, but competition breeds efficiency, so even though the system is a horrible Malthusian hellhole on the inside, it is pretty strong as a whole. But if we try to avoid this and expand as a hive mind, we have to expend a lot of overhead on synchronization and an immune system, but we don't really know what the potential threats are, so the result will be brittle.

It might have an earth-like planet in terms of orbit and composition, but I highly doubt that it would have life on it.

Proxima Centauri is a flare-type star, meaning that it it unpredictably brightens across its entire spectrum from infrared to x-ray. A planet would have to have a really thick atmosphere to protect against that, and a thick atmosphere can easily run away like Venus.

Without a thick atmosphere, any burgeoning life would have to deal with random bursts of energy that could cause damage to that lifes equivalent of genetic coding.

There's no thick atmosphere like ten feet of water.

The frequency absorption of water has a small window around visible light and a sold wall around it. [1]

Maybe the danger of building telescopes on the surface (and the rapid attenuation of their home medium) is why they haven't built any radios to chat with us. ;)

[1]http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/watabs.h...

Techonlogical society can't develop under water.

You can have culture, tools and electrochemistry underwater.

You can't have fire, basic tools maybe, more than that not really. Also doing chemistry underwater is pretty neat impossible. Sure we can do it today, but incremental development is very unlikely.

There is a good chance that any technological species we need will be quite close to us because there are certain criteria that are likely to be met which are pretty universal.

You can have fire underwater, take for example Magnesium torches. Knowing what we know now about technology, it is difficult to imagine getting to this point underwater. But imagine a life form that lived in these conditions from the beginning, and perhaps having tools and doing chemistry may not be so far fetched after all.

Again you are extrapolating the wrong things.

Can't have incremental development underwater.

Magnesium torches have thier own oxidizer.

Find a way to refine magnesium underwater.

I can imagine a lot of things but it doesn't mean it's possible.

Technological life forms are going to be pretty similar to us. Sight, fine motor skills and various other aspects are going to be pretty close.

Why must they be similar to us?

For instance, I completely accept that a sightless entity, as we have sight, could develop a technological culture.

Because you can break down the "required" biological factors and environmental factors for a "technological intelligence", nothing says you can't have a super advanced species of dolphins with complex language, society and philosophy (although philosophy is somewhat limited by scientific progress) but they are quite unlikely to be a technological society.

Here are a few examples:

1) Sight is almost mandatory to be in the visible or near visible (near IR is ok, near UV is possible but pretty unlikely) part of the spectrum for a technologically advanced species to develop. One can also put an effective lower limit on the optical resolution of sight which is favorite or required for enabling higher intelligence, as well as the fact that a technologically advanced species is more likely to be multichromatic than monochromatic. Sight is pretty integral into intelligence development, from looking at the stars to seeing the colors of a rainbow, to developing tools and peaking into the microscopic and macroscopic world.

A species whose sight is based echolocation for example is unlikely to gain sufficient information from the environment to develop high intelligence, and more than that they are quite unlikely to develop complex tools and things like microscopes, telescopes, laser and many other things would be pretty much "inaccessible" to them directly. Echolocation can also hinder or prevent the development of written languages and written language is a very important part of the technological development of society because it is mandatory for low tech information archiving which allows the society to save information between generations.

2) Fine motor skills this puts some base line requirements for appendages a few very nimble tentacles are ok, hands with nimble fingers are great, claws and hooves on the other hand are not. This is because you need to be able to develop very fine tools in order to advance your technology 5 fingers with opposable thumbs might not be a strict requirement but you unlikely to see crab people with only crude claws for grabbing and manipulating things.

3) Land dwelling, land dwelling is almost a must for a progressive incremental development of technology, tool making, fire, projectiles, chemistry, flight, electronics all of these are almost impossible to be developed while submerge. A sufficiently advanced species can compensate by creating "dry" areas under the ocean, but incremental development is near impossible. No meteors, no lighting strikes, and while thermal vents can produce some heat you aren't going to be lighting fire, smelting metal, not to mention building LED's under water.

4) Planetary resources and mineral composition slightly less important but also quite important for higher technological advancements fossil fuels in any forms are going to be pretty important as an energy source, it's unlikely that you'll be able to jump from slavery to fusion without having some energy sources in the middle, you can somewhat compensate with biomass fuels but fossil fuels (doesn't have to be oil) are pretty important. As far as more advanced technologies than the availability of light metals such as aluminum and titanium might be somewhat important as well as "rare earth" elements which are used to make semiconductors. If you somehow evolve on a planet that doesn't have the required resources to build semiconductors (unlikely but somewhat possible) you are some what unlikely to go much beyond the mid industrial phase, given enough time you might be able to compensate and have some steampunk rocketry and tiny electromechanical computers but don't discount how important solid state computers are for technological advancement.

5) Gravity there is an upper limit on the how strong the gravity can be for technological society to develop also with gravity going much beyond 1.5-2 earth's technological advancement becomes less likely both because the implication it would have the physiology of the species that develop under such conditions and because it makes projectiles, flight, and rocketry less likely or even impossible which sets a higher limit on how much a society can advance or at least at what rate.

And there are many other factors that have certain limitations or highly favorable states that need to be met for technological advancement. If we take what we know about evolution, especially converging evolution, what we know is required to build or achieve certain technological advancement and what conditions are required for those things to be likely to occur you get a situation where while life can take any shape form or size it's considerably likely that if one day a spaceship lands and a few E.T. are going to come out of it they would be considerably more similar to us than to a cockroach, snake, turtle, crab or any other shape or form you can imagine life can create, at least externally.

If they could find a way to blow glass underwater, from active volcanoes, they could create dry environments within glassware to do non-aquatic research within.

Hum, I understand the point, but nothing prevents that. An endless supply of fire and molted material under water is a normal event in extensive areas of this planet; in oceanic ridges. The planet earth have also plenty of the finest chemical masters living under water, like cnidarians, molluscs or sponges. They create thousands of products, from sea shell to antibiotics to luminous ink, glue or any venom that we could imagine. To finish, some aquatic organisms had tentacles with a miriad of small independent muscles that could be seen as much more precise tools than hands, those animals are also very smart.

There is some molten material and very hot exhaust sure. Biological chemistry is not technological chemistry, you aren't going to be mixing ash with vinegar, you aren't as likely to see fermentation, you are not likely to be able to smelt metal, cure leather and do many other things that advance your technological capabilities. Writing which is a very important thing is also unlikely to develop underwater, you need writing to preserve the information between generations to enable technological progress. Using chemical energy, and generating electricity is also more unlikely in an industrial setting under water. As for the appendages, hands are not required, very nimble tentacles can work, claws and hooves won't, you need to be able to have fine motor skills to develop tools. I didn't say a smart species can't develop under water, they can, but unless they are directly uplifted they would unlikely to develop into a technological society not to mention a high technological society with space travel capabilities.

Life doesn't always mean intelligent advanced civilisation.

No it doesn't, but it has to be intelligent to build telescopes read the parent comment :)

You can produce gas underwater, though, and build things inside a gas bubble.

Why?

Why do you believe that and what evidence do you have to back up this assertion?

Why can't a semiaquatic species that takes to the waters for shelter during a flare event develop technology?

We have aquatic creatures that can generate electricity on our planet. That's pretty crazy for us. What if it was the norm on another planet? What would the implications for the development of a technological society be in that envolutionary environment?

The assertion that technological society can't develop under water or that fire is a prerequisite for a techological society is too anthropocentric for my liking.

This seems like an important filter when describing the potential for life on a planet. Is it part of the normal discussion when exploring for planets that might have life?

> Without a thick atmosphere, any burgeoning life would have to deal with random bursts of energy that could cause damage to that lifes equivalent of genetic coding.

Is having a thick atmosphere a necessary condition for life?

Is it not possible for a mutation to result in a 'thick skinned' life form - one that relies on its exo-skeleton/skin to withstand the drastic changes? Or a color-changing 'plant' that evolved to do ultra-fast-photo synthesis when needed and move into a dormant mode, when not?

Such a thing would allow such plants and animals to move out of the seas and go onto dominate the land. (Assuming, of course that there is life underwater)

I don't think it's a spoiler to say that this is a major plot point in "The Three Body Problem" by Liu Cixin.

WHAT. That is one implausible SF premise that just allegedly came true there.

They've refused to deny it, so they've confirmed it.

When I saw the headline, I literally went 'Oh come on!' out loud. Apparently there's a bloody Earth-like planet everywhere if even our neighboring star has one.

There's something that always seems to be overlooked by all these discussions about the suitability of exoplanets for extraterrestrial intelligence: Artificial Lifeforms.

Say, if we humans were to build robots, with [true] AI, and they then go on to colonize the other planets in our solar system, would a biological species somewhere ever consider them as a candidate for life?

I mean, machines made of metal and electronics won't need any of that fancy oxygen and water, to be able to survive on Mars or Venus or any of the barren moons, or even float around in the upper layers of Saturn. They would be happily carrying out all the functions we ascribe to "life" and we'd never even think that there would be anything there.

Just look at our current space tech and industry. Robots would definitely be cheaper for the foreseeable future because you don't need any life-support systems, during transit or at site, just sun sun sun batteries sun.

TL;DR: The galaxy just might be full of robotic instead of biological life.

There is almost no time dilation at 50% C this is pretty awesome less than a 10 year trip if we ever manage to build even probes that can go that fast it's pretty much a done deal.

Good enough motivation as any to go through with the Starshot idea.

http://www.space.com/32546-interstellar-spaceflight-stephen-...

Practically the entire universe could be teaming with intelligent life, and we would never know it, given the speed of causality, even without the expansion of the universe.

Sign me up for the expedition.

Dibs!

(I'm sorry, I couldn't help it.)

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