"Alien life deemed impossible"

[baric]

They don't need to be vastly intelligent. They could just have fixed programming to replicate themselves and to attack a specific enemy signature. They could be closer in intellect to a Tomahawk missile than a pigeon.

I think you vastly underestimate the level of autonomous AI that would be required to traverse (and survive) in interstellar space, along with the ability to forage for necessary resources while scouring deep space to satisfy their primal "kill all humans" programming.

In fact, I would argue that all biological life has this same programming, including humans, which most noticeably manifests itself today as the subconscious tendency to dismiss the worth of anything not like us while simultaneously fornicating with anything like us. Yet somehow we have become intelligent enough override those basic impulses -- as opposed to less intelligent animals.

edit: word choice

[IsaacKuo]

I think you vastly underestimate the level of autonomous AI that would be required to traverse (and survive) in interstellar space, along with the ability to forage for necessary resources while scouring deep space to satisfy their primal "kill all humans" programming.

They don't need to forage deep space for all available resources. They could just forage deep space for a specific type of easily identified resource.

For example, suppose icy bodies rich in carbon dioxide ice (among other ices) are common throughout the galaxy. A berserker might "digest" these by heating them up and distilling carbon dioxide from the resulting gas. The carbon dioxide is then split up for the carbon, which can then be used to manufacture more berserkers. In various forms, carbon can be a strong structural material, an electrical insulator, an electrical conductor, an electrical semiconductor, an excellent lens material, an excellent mirror material, an excellent thermal conductor, a good lubricator, an excellent laser sail material...

Basically, if you can imagine it, you can probably build it out of carbon.

BTW, why do you keep on using the expression "kill all humans"? The hypothetical berserkers I describe obviously would not be programmed to kill specifically humans. They would be programmed to attack specific enemies in ancient interstellar wars.

[Zo0tie]

In fact, I would argue that all biological life has this same programming, including humans, which most noticeably manifests itself today as the subconscious tendency to dismiss the worth of anything not like us while simultaneously fornicating with anything like us. Yet somehow we have become intelligent enough override those basic impulses -- as opposed to less intelligent animals.

If you consider the rate of extinction of other species and the rate of destruction and degradation of natural habitats I don't think we have overridden our basic impulses. On a macroscopic scale we still function as a vast biological planetary killing machine. We may be our own filter. It may be very natural for technological intelligence to cut off its own interplanetary expansion through environmental collapse on its home world. Like a dodder vine that is too far away from other brush, it shrivels up and dies after killing off it's host bush. Give it 20-50 years to see if I'm right.

[kzb]

They don't need to forage deep space for all available resources. They could just forage deep space for a specific type of easily identified resource.

For example, suppose icy bodies rich in carbon dioxide ice (among other ices) are common throughout the galaxy. A berserker might "digest" these by heating them up and distilling carbon dioxide from the resulting gas. The carbon dioxide is then split up for the carbon, which can then be used to manufacture more berserkers. In various forms, carbon can be a strong structural material, an electrical insulator, an electrical conductor, an electrical semiconductor, an excellent lens material, an excellent mirror material, an excellent thermal conductor, a good lubricator, an excellent laser sail material...

Basically, if you can imagine it, you can probably build it out of carbon.

BTW, why do you keep on using the expression "kill all humans"? The hypothetical berserkers I describe obviously would not be programmed to kill specifically humans. They would be programmed to attack specific enemies in ancient interstellar wars.

The Berserker scenario unfortunately is one of the few logically consistent solutions to the FP.

The most common argument against it is, for an alien civ to survive for a long period, it must be of a peaceful outlook and therefore benign. However I am not that convinced by this, it only takes ONE civilisation (or even a rogue organisation within that civilisation) to think it would be a good idea to create Lebensraum in the Galaxy. Then we could easily have the "deadly probes" phenomenon.

All organisms are essentially competitive. Our whole economic model (which is held to be far superior in outcome than more co-operative models) is based on cut-throat competition.

[baric]

BTW, why do you keep on using the expression "kill all humans"? The hypothetical berserkers I describe obviously would not be programmed to kill specifically humans. They would be programmed to attack specific enemies in ancient interstellar wars.

I was using "humans" as a metaphor for biological organisms, including us. And I like Bender on Futurama.

Here's how interstellar wars will go.

1) Race A decides Race B is a risk

2) Race A launches 500-lb probes to Race B's colonized planets (Race A thinks metric system used by Race B is heresy)

3) Probes directly impact Race B's planets at 0.1c

4) Race B is dead.


No need for berserker robots.

[kzb]

While I tend to agree with this expectation, there are a few potential countervailing factors.

One is risk aversion. We modern humans expect a certain level of safety, which exceeds the "bad old days" of just a century ago when simply eating or drinking the water could be a life threatening activity. The somewhat elevated risk of deadly cancer from space radiation exposure might not seem a big deal if it's a round-off error compared to other causes of death. But improving technology might change the acceptable level of risk.

Another is ping time aversion. High tech humans or AI entities might be "addicted" to the 'net, and the thought of multi-hour or multi-day long ping times may be deal-killers. An AI which thinks a thousand times faster than a human might find ping times for any BEO travel to be excruciating.

I can't agree these are reasonable explanations of the FP ! The Galaxy has remained uncolonised for billions of years because of risk aversion and slow net connections ?

We have already made a small start on announcing ourselves via space probes: the plaques on the Voyager probes. Probably no real chance they would be found because they were not targeted. But it does show that we are not a long way off being able to do this in a bigger way.

Earth-like planets are currently being searched for. Probably not too long now and location data on these will be available. Simple messenger probes could be launched to these with only modest technological advancement on current capabilities. OK they would take millenia to get there, but that is an eyeblink in the history of the galaxy.

[IsaacKuo]

The Berserker scenario unfortunately is one of the few logically consistent solutions to the FP.

The most common argument against it is, for an alien civ to survive for a long period, it must be of a peaceful outlook and therefore benign. However I am not that convinced by this, it only takes ONE civilisation (or even a rogue organisation within that civilisation) to think it would be a good idea to create Lebensraum in the Galaxy. Then we could easily have the "deadly probes" phenomenon.

I would have thought the most common argument against it is the fact that they haven't already killed us.

If berserkers were designed to eliminate all potential rivals, then it seems to be completely illogical to wait until after a potential rival has developed space travel, nuclear weapons, high tech computers, etc. It would take so much less effort to simply sterilize planets in their infancy.

But of course, this argument assumes that the design goal of the berserkers is to exterminate all potential rivals. I am pondering possibilities where the berserkers are designed to fight specific enemies rather than exterminating all potential rivals whole cloth.

All organisms are essentially competitive. Our whole economic model (which is held to be far superior in outcome than more co-operative models) is based on cut-throat competition.

No, functional human societies actually involve a lot of cooperation. It's certainly a combination of cooperation and competition, but very heavily tilted toward cooperation. Even in dysfunctional societies where cooperation seems to have broken down (like Somalia), there is actually still a high degree of cooperation. It's just that unfortunately this cooperation is among members of organizations of violent thugs.

[IsaacKuo]

I was using "humans" as a metaphor for biological organisms, including us. And I like Bender on Futurama.

Well, the scenario I ponder doesn't involve berserkers going after biological organisms in general. Some may be designed to go after particular biological species. Most may be designed to go after robotic enemies--namely, other berserkers.

Here's how interstellar wars will go.

1) Race A decides Race B is a risk

2) Race A launches 500-lb probes to Race B's colonized planets (Race A thinks metric system used by Race B is heresy)

3) Probes directly impact Race B's planets at 0.1c

4) Race B is dead.


No need for berserker robots.

If these probes head for Race B's planets at 0.1c, Race B might see this attack coming decades or centuries or millenia away. During this time, Race B might try to evacuate at least some of the planets and/or develop defenses to shoot down those 500-lb probes.

Or maybe Race B has no evacuation options, and the attack is so overwhelming that defense is hopeless. They might not be able to evacuate if, for example, they evolved in the water-ammonia mantle of an ice giant and their biology simply can't survive the lower pressures of a physically possible spacecraft.

In any case, Race B has the option of revenge. Rather than launch expensive 250kg probes at Race A's habitats (Race A lives on trillions of space habitats), they decide to launch berserkers. The berserkers are self replicating machines which exponentially increase their numbers. This gives them a chance of eventually overwhelming Race A, even if Race B never lives to see it.

Maybe the berserkers overwhelm Race A eventually. Maybe Race A survives, and figures out how to avoid the berserkers by avoiding the emission signatures the berserkers recognize. Maybe Race A builds their own berserkers to exterminate the Race B berserkers.

In any case, there's now one or two leftover infestations of berserkers roaming around the galaxy.

What happens when they run into Race C? Well, some of Race C's habitats may accidentally produce emissions that look like what the enemy to the berserkers. They attack, starting yet another interstellar war! The berserker attacks may seem mysteriously half-hearted, since they only attack some of Race C's habitats some of the time, instead of sustaining their attacks to finish the job. No matter, they're still a problem that Race C has to deal with. They eventually study the attacking berserkers enough to design their own berserkers to exterminate them. This adds another infestation of berserkers to the galaxy...

[baric]

If these probes head for Race B's planets at 0.1c, Race B might see this attack coming decades or centuries or millenia away. During this time, Race B might try to evacuate at least some of the planets and/or develop defenses to shoot down those 500-lb probes.

That was an illustrative example. A hyper-advanced civilization capable of interstellar travel and intent on war with a comparable civilization would certainly launch their impactors at whatever speed is necessary to get the job done.

My point is that, when you have the capability of generating the delta-v needed for interstellar travel, then destroying the biosphere of any planet you choose becomes as trivial as simply not slowing down before arrival. There is no need to amass an army of self-replicating robots.

[IsaacKuo]

That was an illustrative example. A hyper-advanced civilization capable of interstellar travel and intent on war with a comparable civilization would certainly launch their impactors at whatever speed is necessary to get the job done.

Easier said than done. Interstellar travel doesn't need near-c velocities, and anything moving at near-c velocities will have a difficult or impossible time making guidance corrections to hit a space habitat or spacecraft. From the perspective of a near-c missile, the target space habitat/vehicle is screaming at it at near-c velocities, giving it hardly any reaction time.

My point is that, when you have the capability of generating the delta-v needed for interstellar travel, then destroying the biosphere of any planet you choose becomes as trivial as simply not slowing down before arrival. There is no need to amass an army of self-replicating robots.

Planets are quaint. Space habitats could provide many orders of magnitude more living space than planets, here in our solar system.

And in any case, self-replicating robots wouldn't depend on the existence of any biosphere on any planet. In most of the wars in this scenario, the enemy is an infestation of self-replicating robots. Bombing planetary biospheres will have no effect on this sort of enemy.

[baric]

Easier said than done.

You're the one positing an interstellar war with armies of killer drones. I'm just accelerating a ship to relativistic velocities.

[IsaacKuo]

You're the one positing an interstellar war with armies of killer drones. I'm just accelerating a ship to relativistic velocities.

If it's just "relativistic" velocities, then you give the enemy at least years--maybe centuries--of advance warning. To do the sort of surprise attack you're hoping for, you need near-c velocities. Not only that, but the acceleration period itself must be very short. Like I said, easier said than done.

And remember, your surprise attack has to wipe out everyone. Because if there are any survivors, they are going to make revenge a big part of their existence from then on (possibly the only part of their existence they ever care about, ever again). These survivors could be in spacecraft at the time the attack arrives. They could be in space habitats that didn't even exist at the time you launched the attack.

[baric]

If it's just "relativistic" velocities, then you give the enemy at least years--maybe centuries--of advance warning. To do the sort of surprise attack you're hoping for, you need near-c velocities. Not only that, but the acceleration period itself must be very short. Like I said, easier said than done.

How exactly do you detect a ship moving at relativistic speeds?

[IsaacKuo]

How exactly do you detect a ship moving at relativistic speeds?

Given the incredible amounts of energy involved during initial acceleration, the initial acceleration run is probably the most blatantly visible thing. Laser or particle beam propulsion would be the most visible possibilities, since they involve a torrent of energy particles pointed in your direction. Some sort of nuclear or antimatter based drive would be next in visibility, involving oodles of x-rays and/or gamma rays. Some sort of extremely long mass driver might be less visible, but this involves heroic megaengineering--like multi-AU long barrels and Faraday cages to conceal the EM waves--and the prodigious waste heat would still be visible.

Maybe there is some stealthy relativistic acceleration technology that's remotely plausible, but I don't know what.

[baric]

Maybe there is some stealthy relativistic acceleration technology that's remotely plausible, but I don't know what.

Let me be clear about my reservations to your killer robot theory.

You object to the notion that an advanced civilization with the capability of interstellar travel would be able to launch an impactor at extremely high speeds into a large body, but yet this same civilization is capable of building swarms of autonomous killer robots to search and traverse the galaxy for enemies.

When questioned if their AI would be smart enough to override their basic programming (as with biological forms), you suggested they could be as dumb as cruise missiles. But when asked how they would survive the rigors of interstellar travel, you suggested that they could be smart enough to find CO2 ice and extract carbon from it to make whatever they needed.

You question in detail the how an impactor can be propelled at great speeds and how any propulsion would be detectable, but yet show no similar skepticism about the propulsion capabilities of your robot swarm.

I know that you are really keen on this idea, but its grounding with scientific principles is tenuous, at best. (in my opinion, of course)

[IsaacKuo]

Let me be clear about my reservations to your killer robot theory.

You object to the notion that an advanced civilization with the capability of interstellar travel would be able to launch an impactor at extremely high speeds into a large body, but yet this same civilization is capable of building swarms of autonomous killer robots to search and traverse the galaxy for enemies.

No, I object to the notion that they would be able to launch near-c missiles to not just large bodies--but ALL enemy habitats and spacecraft. Without that awesome capability, the type of attack you talk of would leave survivors. Those survivors could plausibly use something like berserkers to try and exact revenge, even if the original attackers didn't use them.

I'm arguing against your premise that berserkers are never used because interstellar wars would always be simple affairs where one side simply launches a surprise attack that completely wipes out the other side instantly. I do not find this plausible.

Note that you need to argue that interstellar wars NEVER use any berserkers. I'm not arguing that berserkers are always used, only that it's plausible for them to sometimes be used.

When questioned if their AI would be smart enough to override their basic programming (as with biological forms), you suggested they could be as dumb as cruise missiles. But when asked how they would survive the rigors of interstellar travel, you suggested that they could be smart enough to find CO2 ice and extract carbon from it to make whatever they needed.

I gave that example because it does NOT require smarts. It only requires the same level of dumbness as a cruise missile. Searching for a small body and homing in on it is much the same as searching for a warship and homing in on it.

You question in detail the how an impactor can be propelled at great speeds and how any propulsion would be detectable, but yet show no similar skepticism about the propulsion capabilities of your robot swarm.

Not just great speeds--near-c speeds. You need near-c speeds to do a surprise attack, but unfortunately this also blinds you to the motion of the enemy targets. These are physics limitations which make near-c surprise attacks difficult at best.

Beserkers don't need near-c speeds. They don't even need relativistic speeds. A beserker design might not even be explicitly designed for interstellar warfare. Beserkers designed to exploit small icy bodies could simply spread throughout an Oort cloud and eventually go interstellar as the Oort clouds of passing star systems overlap.

I know that you are really keen on this idea, but its grounding with scientific principles is tenuous, at best. (in my opinion, of course)

I object to your notion on the basis of physics as we currently know it.

[KABOOM]

Back to a few, non-exhaustive pillars of the Rare Earth theory that suggest that we (as an intelligent species with advanced technology) are very, very rare (perhaps N=1 as it pertains to the current Milky Way). I note that that book is ~ 11 years old so perhaps some of these premises have been debunked or at least counter-balanced by equally plauisible counter-arguments (backed by valid sceince) and if so I would appreciate any illumination on this issue.

1) The presence of a large moon (as a % of host planet size). Now viewed as formed via a collison with a ~ Mars-sized object during Earth's smaller formative period (hence, a very unique happenstance). The moon keeps Earth's obliquity stable (~ 23 degrees), thus this greatly enhances Earth's climate stability (even allowing for ice ages, and Snowball Earth periods). Without this stability I have seen it suggested that Earth's axial tilt could swing by up to 80 degrees from time to time, rendering the evolution of animal life problematic at best.

2) The role of Jupiter. I have heard that there are more recent views that contest the importance of Jupiter in the development of Animal Life on Earth. The original premise is that Jupiter formed early and sucked up a lot of the cosmic debris that otherwise would have resulted in more frequent comet/meteor/asteroid collisions with Earth. Also since Jupiter has a stable orbit itself, its large gravity forces tend to "deflect or absorb" a certain amount of debris that would otherwise interfere with the inner planets.

3) Earth is the only known planet in the Milky Way with active plate tectonics. Plate tectenoics arguably serve as a stablizer (long term) of climate, enhance bio-diversity through seperation of habitable continents and likely are required for the iniation and sustainment of continents in the first place. Also, plate tectonics seem to be required for the presence of a large magnetic field to protect a planet from radiaion.

4) The likelihood of an Earth-like planet in small (below G) star systems. Planet would have to be much closer and thus tidal locked, rendering Animal Life a long shot (impossible?).

Items 1 and 3 seem essential for the development of Animal Life (a precursor to the evolution of intelligent, technical life) and since both seem incredibly rare it would serve to significantly reduce the odds for Animal Life elsewhere

[baric]

1) The presence of a large moon (as a % of host planet size). Now viewed as formed via a collison with a ~ Mars-sized object during Earth's smaller formative period (hence, a very unique happenstance). The moon keeps Earth's obliquity stable (~ 23 degrees), thus this greatly enhances Earth's climate stability (even allowing for ice ages, and Snowball Earth periods). Without this stability I have seen it suggested that Earth's axial tilt could swing by up to 80 degrees from time to time, rendering the evolution of animal life problematic at best.

We have two examples in our system alone of large moons created by collision. That suggests it is not as uncommon as we might think.

2) The role of Jupiter. I have heard that there are more recent views that contest the importance of Jupiter in the development of Animal Life on Earth. The original premise is that Jupiter formed early and sucked up a lot of the cosmic debris that otherwise would have resulted in more frequent comet/meteor/asteroid collisions with Earth. Also since Jupiter has a stable orbit itself, its large gravity forces tend to "deflect or absorb" a certain amount of debris that would otherwise interfere with the inner planets.

Simulations now show that the presence of Jupiter has had little protecting effect on Earth. http://arxiv.org/abs/0806.2795

3) Earth is the only known planet in the Milky Way with active plate tectonics. Plate tectenoics arguably serve as a stablizer (long term) of climate, enhance bio-diversity through seperation of habitable continents and likely are required for the initiation and sustainment of continents in the first place. Also, plate tectonics seem to be required for the presence of a large magnetic field to protect a planet from radiation.

"Active". Other planets have evidence of past geological activity so, given liquid water, it's not unreasonable to assume other planets will have tectonic activity as well. The bigger issue, imo, is for a planet to have just barely enough water to support tectonics, but not so much that it is covered in oceans.

4) The likelihood of an Earth-like planet in small (below G) star systems. Planet would have to be much closer and thus tidal locked, rendering Animal Life a long shot (impossible?).

I'm not following that. Why would life be impossible on a tidal locked planet?

I want to make sure that you are not simply throwing out objections just to see if they'll stick on the wall.

Items 1 and 3 seem essential for the development of Animal Life (a precursor to the evolution of intelligent, technical life) and since both seem incredibly rare it would serve to significantly reduce the odds for Animal Life elsewhere

#1 is most likely not rare. #3 might be if it hinges on a narrow band of water content.

[KABOOM]

I'm not following that. Why would life be impossible on a tidal locked planet?

I want to make sure that you are not simply throwing out objections just to see if they'll stick on the wall.



#1 is most likely not rare. #3 might be if it hinges on a narrow band of water content.

Thanks for the response and link.

What is the 2nd example of a moon formed within our solar system via collision? I understand that Pluto has a moon that on a relative basis is as ~ large as our moon is to Earth.

Tidal-locked planets and animal life. My understanding is that Animal Life needs stable temperatures (within 5 to 45 degrees C). The darks side of tidal locked planets produces very cold temperatures which cause the related atmosphere to "freeze out". Thus the ability of a tidal locked planet to maintain an atomosphere is compromised, hence no Animal Life at least that was stated with certitude by Ward/Brownlee in "Rare Earth".

[baric]

Thanks for the response and link.

No problem. I have so many pdfs saved off on my computer for reading. I just googled the title and was happy to see that you could still read it online

What is the 2nd example of a moon formed within our solar system via collision? I understand that Pluto has a moon that on a relative basis is as ~ large as our moon is to Earth.

Yes, a collision genesis is the current working theory for Charon. There's really no other known mechanism that can end up with a planet:moon mass ratio so low.

Tidal-locked planets and animal life. My understanding is that Animal Life needs stable temperatures (within 5 to 45 degrees C). The darks side of tidal locked planets produces very cold temperatures which cause the related atmosphere to "freeze out". Thus the ability of a tidal locked planet to maintain an atomosphere is compromised, hence no Animal Life at least that was stated with certitude by Ward/Brownlee in "Rare Earth".

Right. However, it is possible for an atmosphere to be thick enough so that heat is transferred sufficiently around the planet to prevent a freeze-out on the dark side. It would be extremely windy, though, so that would add another complication into the evolution of life.

[IsaacKuo]

1) The presence of a large moon (as a % of host planet size). Now viewed as formed via a collison with a ~ Mars-sized object during Earth's smaller formative period (hence, a very unique happenstance). The moon keeps Earth's obliquity stable (~ 23 degrees), thus this greatly enhances Earth's climate stability (even allowing for ice ages, and Snowball Earth periods). Without this stability I have seen it suggested that Earth's axial tilt could swing by up to 80 degrees from time to time, rendering the evolution of animal life problematic at best.

As already noted, it seems that large collision caused moons may not be so uncommon. Additionally, I'll note that there are other possibilities. The habitable "planet" in question could actually be a moon in orbit around a gas giant or brown dwarf. This would keep its tilt stable with respect to the main star.

Also, I'm skeptical that being tide-locked is a deal killer. A tide-locked planet would also have a stable climate.

3) Earth is the only known planet in the Milky Way with active plate tectonics.

You mean Earth is the only planet with known currently active plate tectonics. There are only 4 planets for which we have any relevant data. One in four doesn't seem "incredibly rare".

If you include moons, some of the gas giant moons show evidence of plate tectonics. Even more moons and planets show evidence of significant geological activity that may serve the purposes of plate tectonics.

4) The likelihood of an Earth-like planet in small (below G) star systems. Planet would have to be much closer and thus tidal locked, rendering Animal Life a long shot (impossible?).

I'm skeptical of the idea that a tide locked planet is a deal killer.

[Githyanki]

The habitable "planet" in question could actually be a moon in orbit around a gas giant or brown dwarf. This would keep its tilt stable with respect to the main star.

How could life survive in the gas-giant's radiation-belts?

[IsaacKuo]

How could life survive in the gas-giant's radiation-belts?

A) Not all gas giants have strong radiation belts. The only one we know of is Jupiter's. Still, we theorize that larger gas giants and brown dwarfs are more likely to have strong radiation belts.

B) Not all moons are in the radiation belts. For example, Callisto is a large moon which orbits Jupiter outside its radiation belt.

C) A gas giant moon may have natural radiation shielding in the form of a magnetic field (Ganymede) or a thick atmosphere (Titan) or a thick ice crust (Europa).

In the specific case of an ocean mantle biosphere, such as may exist in Europa, a strong radiation field may actually be a good thing. Radiation hitting water ice generates oxygen, which is theorized to make its way down below the crust thanks to geological activity. This may provide an important stable long term source of oxygen to an ocean mantle biosphere.

[Noclevername]

C) A gas giant moon may have natural radiation shielding in the form of a magnetic field (Ganymede) or a thick atmosphere (Titan) or a thick ice crust (Europa).

In the specific case of an ocean mantle biosphere, such as may exist in Europa, a strong radiation field may actually be a good thing. Radiation hitting water ice generates oxygen, which is theorized to make its way down below the crust thanks to geological activity. This may provide an important stable long term source of oxygen to an ocean mantle biosphere.

So could Europa's ocean have enough O2 to support large, complex multicelled life?

[eburacum45]

So could Europa's ocean have enough O2 to support large, complex multicelled life?

Perhaps.
Jupiter's Moon Europa Has Enough Oxygen For Life
Even if Europa doesn't have sufficient oxygen, this mechanism is plausible enough that it may allow for oxygen-rich moons orbiting extrasolar planets somewhere else.

[Noclevername]

Interesting! Thanks. It changes my view of Europa's potential.

[Trakar]

We have two examples in our system alone of large moons created by collision. That suggests it is not as uncommon as we might think...

Which "two"?

[Noclevername]

I think he's referring to Earth/Moon and (hypothetically) Pluto/Charon.

[Githyanki]

Thanks Kuo, I wanted to see some good objections.

Can Europa have too much oxygen for life?

Naturally occurring oxygen has a lot of potential to power macrofauna that doesn't rely on sunlight to live.

[baric]

I think he's referring to Earth/Moon and (hypothetically) Pluto/Charon.

It's based on Charon's derived low-density composition in a similar fashion to the moon.