The strongest evidence for alien life - perhaps

[BridgeConsoleMasher]

If they're trapped under radiation then it sounds like they might need our help.

Presumed life on K2-18b doesn't need to worry about the radiation itself. It has existed under these circumstances (by earthly comparison) for presumably almost as long as the planet itself had been around (remember, life on Earth practically definitly started even before all the Earth's crust had become solid, along an event that is called the Late Heavy Bombardement, an event that was caused basically by all the planets in our solar system wandering around for several houndred million years, before they settled into their current orbits)*. If life survived the radiation exposure on K2-18b until today, then that means it has adapted to the radiation. It will be as natural to them, as living with a highly corrosive and extremely reactive molecule like oxygen is to us.

What they need to worry about though is, their distinct lack of oxygen. Due to oxygen being readily available to us, it doesn't even occure to us, how reliant our technologies are on it's existence. No oxygen means no fire, no fire means no artificial warmth and source of potent and controlable energy, means no higher technology beyond simple stone tools at most. Heck, they wouldn't even know how to cook food, because they wouldn't be able to create a fire, as not even a lightning strike could randomly create one, due to the absences of oxygen.
Although imagining what is going to happen when lightning strikes in a hydrogen-rich atmosphere that somehow ends up with a localized oxygen surplus is kinda something I'd like to see, because water-rain and instant cloud-formation as a result of a violent exothermal runaway reaction in a giant fireball should kinda be a sight to behold once in your life (though, security reminder: experiencing that event in person will be your terminal sight to behold).

Worse yet, no oxygen also means no highly potent source of energy on a cellular level. It's borderline impossible to imagine a complex multicellular life-form without mitochondria or a comparable specialized organism producing an excess of energy for whatever other organism joined into a symbiosis with it, beyond a fungi (at the most complex).

*It needs to be emphasized, that the earliest traces of life can be found during the Late Heavy Bombardment. That does not mean, however, that life on Earth didn't exist before already. All traces of which would've been eradicated during the Late Heavy Bombardment at latest, but definitly 300 million years earlier, during whatever specifically caused the formation of the moon (which resulted in the definite firey liquidation of anything even remotely solid on Earth before that point in time; even though depending on what exactly caused the formation of the Moon, Earth wasn't technically Earth yet, because what is Earth after the formation of the Moon might very well be the amalgam of two previously distinct celestial bodies).

Sounds like we could learn a lot from them and vice versa. We should probably focus on that rather than all the differences.

[McAvoy]

I actually do wonder how life would thrive should there be something as simple as oxygen not be present. Off hand, hydrogen?

If oxygen was needed for life, it would certainly limit the planets where life could form.

[Riedquat]

I actually do wonder how life would thrive should there be something as simple as oxygen not be present. Off hand, hydrogen?

If oxygen was needed for life, it would certainly limit the planets where life could form.

It's the reaction that's needed, here it's oxygen + something. I suppose as long as the place isn't in chemical equilibrium there's a chance. It's hard to know what's possible when we've got an example of a grand total of one planet to look at.

[BridgeConsoleMasher]

Yeah our own bodies use oxygen to burn fats for energy. It's what elevated breathing is for during continual exercise. Given they have lots of hydrogen I assume they use carbohydrates,, that is if they are carbon based life forms. I do NOT want to get ahead of myself and assume things here.

[clearspira]

https://www.bbc.co.uk/news/articles/c728ven2v9eo

Here is an interesting article that I have found. Scientists discovered in 2024 a previously unknown phenomenon here on Earth that they have dubbed ''Dark oxygen'' which has enormous possibilities on the search for ET life. To quote:

Scientists have discovered “dark oxygen” being produced in the deep ocean, apparently by lumps of metal on the seafloor.

About half the oxygen we breathe comes from the ocean. But, before this discovery, it was understood that it was made by marine plants photosynthesising - something that requires sunlight.

Here, at depths of 5km, where no sunlight can penetrate, the oxygen appears to be produced by naturally occurring metallic “nodules” which split seawater - H2O - into hydrogen and oxygen.

“I first saw this in 2013 - an enormous amount of oxygen being produced at the seafloor in complete darkness,” explains lead researcher Prof Andrew Sweetman from the Scottish Association for Marine Science. “I just ignored it, because I’d been taught - you only get oxygen through photosynthesis.

“Eventually, I realised that for years I’d been ignoring this potentially huge discovery,” he told BBC News.

He and his colleagues carried out their research in an area of the deep sea between Hawaii and Mexico - part of a vast swathe of seafloor that is covered with these metal nodules. The nodules form when dissolved metals in seawater collect on fragments of shell - or other debris. It's a process that takes millions of years.

And because these nodules contain metals like lithium, cobalt and copper - all of which are needed to make batteries - many mining companies are developing technology to collect them and bring them to the surface.

The scientists worked out that the metal nodules are able to make oxygen precisely because they act like batteries.

“If you put a battery into seawater, it starts fizzing,” explained Prof Sweetman. “That’s because the electric current is actually splitting seawater into oxygen and hydrogen [which are the bubbles]. We think that’s happening with these nodules in their natural state.”

“It's like a battery in a torch,” he added. “You put one battery in, it doesn't light up. You put two in and you've got enough voltage to light up the torch. So when the nodules are sitting at the seafloor in contact with one another, they’re working in unison - like multiple batteries.”

The researchers put this theory to the test in the lab, collecting and studying the potato-sized metal nodules. Their experiments measured the voltages on the surface of each metallic lump - essentially the strength of the electric current. They found it to be almost equal to the voltage in a typical AA-sized battery.

This means, they say, that the nodules sitting on the seabed could generate electric currents large enough to split, or electrolyse, molecules of seawater.

The researchers think the same process - battery-powered oxygen production that requires no light and no biological process - could be happening on other moons and planets, creating oxygen-rich environments where life could thrive.

[McAvoy]

I actually do wonder how life would thrive should there be something as simple as oxygen not be present. Off hand, hydrogen?

If oxygen was needed for life, it would certainly limit the planets where life could form.

It's the reaction that's needed, here it's oxygen + something. I suppose as long as the place isn't in chemical equilibrium there's a chance. It's hard to know what's possible when we've got an example of a grand total of one planet to look at.

Yeah I don't have that sort of scientific background to figure out how lifeforms would form without oxygen.