Why extraterrestrial life may not seem alien

> That Star Trek trope of "everything in the Universe is just like us with different faces" really needs to be put to rest.

Budget constraints aside, Star Trek aliens were used as a prop to explore extremes of terrestrial human behaviour and culture from an outside perspective - take a human and remove emotions and have them governed purely by logic, you get a Vulcan. Take a human and exaggerate their tendencies towards violence and honour, you have a Klingon, and so on.

Even in the original series there were truly alien aliens - for example the Squire of Gothos was a being of pure energy who just assumed human form, Devil in the Dark had a silicon-based creature, and the Tholians were an intelligent crystalline species who could only exist in high temperatures.

Even if you discount the semi-canonical explanation that the Alien was a mixture of human & "entirely fabricated" DNA, Giger's Alien was shaped the way it was for literally- and metaphorically-painful sexual artistic reasons, not as a serious hypothesis for alien life.

> First we need to decide how intelligent are the dolphins, then let us look at the stars.

The premise is wrong. The premise here is that intelligence is the only factor. Physics doesn't allow dolphins to enter the bronze age. Hell, even if dolphins grew arms and hands they couldn't enter the bronze age. They're probably smart enough to do so, but there are other factors limiting them.

We have looked at Earth. We can look to the stars at the same time. It isn't an "or" operation.

> Even H.R. Giger was boring and unimaginative with regards to how he envisioned the Alien. That's clearly a creature influenced by Earth-ism - a quadruped, with a single head and mouth and a flexible spine and claws, it's basically a weird cat.

When the franchise came into being, you're probably right. But in all fairness, the back story and the biological concepts in the Alien universe has been refined since then. For example, the human-like qualities of the xenomorph creature is now explained by the biological merger of an alien substance with the host. When a human was infected, the substance developed into a parasite that took-on characteristics of the host.

Fundamentally, the black goo (i.e. the substance) we saw in Prometheus was pretty much the source of all the alien creatures. It was basically an instrument that deconstructed existing life forms and rebuilt weaponised variants of them.

Honestly this would be pretty hard to imagine. Even if we had no concept of fish (which I find extremely unlikely given other evolutionary pressures, physics, and mechanics of life, but let's not go there) we would think "birds, but in a denser fluid." I don't think this would be "absolutely shocking" to biologists of that planet. Similarly like how biologists here have predicted methane based lifeforms. Now if we were talking about a fluid like sulfuric acid then yeah, that would be absolutely shocking, but not for the reasons of breathing (it's about electrons).

Both mammals and reptiles that live in the water use very similar methods even though they are not at all closely related. It is an example of convergent evolution.

No, its more like saying “our star and the planets and most satellites in the solar system are generally spherical due to gravity. I postulate that all stars and planets in the universe are subject to those same forces and will also generally be spherical”. That isn’t a dangerously intolerant idea. We can say that life is unlikely to arise from a solid block of iron, due to what we understand about the atomic properties of iron, the possible chemical reactions, etc. There just isn’t much going on at a basic physics level for it to “do” anything that could likely lead to even the most generous definition of “life”. That isn’t naivete.

It is your kind of fantastical thinking that life somewhere else somehow isn’t subject to the same physics as life here that is naive. It’s not wanting to be bound by boring concepts like chemical reactions, gravity, perceiving your environment in some way, etc. We don’t take people seriously that say that stars in other galaxies are actually the heads of long bright snakes and us thinking they are just boring balls of gas is our “blindspot”.

What are we referring to as humanoids though? And what are we about as intelligent? Crows? Crows aren't going to build spaceships and don't really have the means to because a beak isn't a great manipulator, even though they use tools. I don't think the person above is saying that quadrupeds would be out of the realm of possibility (maybe they are. IDK I'm a computer scientist, not a biologist. I could totally see body size, caloric intake ratios, and brain mass being related in a way that would make these unlikely), but rather things like fractaling appendages would be expected because intelligent life would need to have fine motor control. (Is a centaur humanoid?) There are just more efficient ways to do things than other ways. Yeah, maybe alien life will have a beak. Maybe their pupils will look different but I'd still expect them to have eyes with squishy lenses because that's pretty much required to be able to focus and intelligent creatures need to be able to sense things both near and far (without technological enhancements). Light sensing isn't enough if you want to build things, you need depth perception. I think if you follow this line of reasoning you'll find that a lot of attributes humans have would be pretty likely for intelligent alien life as well.

Arms+hands and a head with a similar face though.

A head is pretty universal because eyes are so important and a feeding hole near your sensory organs is a massive advantage.

Having hands seems almost a pre-requisite to become truly intelligent and tool-using.

Hm. We have what, a dozen or more on Earth? Apes, monkeys, homo etc. Plus dozens of dinosaurs that stood on 2 legs. It seems pretty common.

Bony fish evolved in rivers, and eventually returned to the sea to kick... what? Analogies fail.

Those fish are overwhelmingly more closely related to horses than to sharks.

> We essentially have only two lineages of macroscopic organisms that are actually fundamentally different: Plants and animals.

That's not true, we also have fungi as a macroscopic lineage.

Or maybe you put them in the plant group? If so, that's a mistake, as they are more closely related to animals than they are to plants.

DNA is extremely flexible, there's no macroscopic form or shape it can't take, as various insects camouflaging themselves as sticks and leaves and what not shows.

So the idea we'll see some vastly different concepts with different starting blocks is possibly unfounded.

Alien life might be very different at low level depending on their environment, but in terms of macroshapes, things like the formation of a head with eyes and mouth, upper and lower limbs, bilateral symmetry and so on will repeat over and over.

We'll see (in another life probably).

It’s a question of physics not just chemistry. Deuterium for example is similar to hydrogen chemically so while those differences are slightly toxic to us it’s easy to assume a planet similar to earth with an abundance of deuterium and a lack of hydrogen would evolve life forms with the opposite preferences.

Except the ratio of hydrogen to deuterium is a function of astronomy and more specifically fusion. No naturally formed planet is going to end up with that imbalance. Which means no natural deuterium based life forms. So while some alien civilization create deuterium life, it’s not going to be part of natural ecosystems.

And so it goes for most possible interesting edge cases. Dependency on rare elements like Neptunium means any competitors without that dependency have huge advantages.

> seeing as Earth alone has billions of years left where such life could arise,

In case you didn't know, Earth has about one billion years of water left.

https://www.sciencedaily.com/releases/2013/12/131216142310.h...

I would say, get your head out of your edge cases. Before I go on, I hope you understand no one is saying its not physically possible, and that it absolutely does not exist anywhere in the multiverse, just that if we come across other life, it will most likely be similar to our own.

by definition, the most probable form of life in the universe is the 1 we are observing. you only need math and probability to figure that out. We also have observational evidence. As far as we can tell, there is no other life in our solar system. We have 8 other planets and many moons that have failed at creating life in any form - that's literally hundreds of billions of years of failed attempts at life.

you can't just pick an element and think its going to work. you need ALL the elements, ALL the states of matter, and the right ratios and amounts of elements to work. Even if you get that lined up, expecting complex life to form under enough pressure to create diamonds in thousands of degrees centigrade also puts the probability of complex life off the table.

I don't known who this is hard to understand. in the simplest example as the article states, if you want to fly, there are things that necessitate something that will fly, such as wings. no wings, no fly. sure its POSSIBLE you can fly without wings, but UNLIKELY. given that we have multiple lineages of evolution taking different paths that end up with the same solution is evidence of that.

Doesn't it intuitively seem like the life by definition would evolve out of any particular niche - say 1,000 Kilometers under the surface - to other areas?

I'm at best doubtful about life on Mars because I find it hard to imagine some form of life that occupies a small part of Mars i.e. it's only in the parts we haven't seen. I tend to think if there's any life on Mars it'll find a way to deal with the conditions on all of Mars. By the same token if there's any silicon based life then it'll pop up in places that we can find as well as those we can't. Maybe it does best in places we can't but surely there would be some oddball silicon based creature that would beat the odds.

The macro example would be the extinction of the South American marsupials when the North and South American land masses merged. All the placental animals in North America went south and all the marsupials in South America went extinct. Except for Opossums which for whatever weird reasons not only survived but went into North America.

Carbon is a way better chemical for life than silicon. It can form vastly longer chains and produces IIROCC (if I recall organic chemistry correctly) much more robust bonds.

Additionally we find organic molecules everywhere from comets to gas clouds in galaxies. We don't really find as much interesting silicon-based chemistry everywhere.

Stars that formed in nebulae that had 2 previous cycles of star formation and super novae.

This means that the star’s solar system at that point has sufficient quantities of heavy elements which cannot be produced by stellar fusion, as these elements are produced by super novae and from solar radiation.

Basically all the neutrons that are produced when a star goes boom create the elements that are above iron in the periodic table.

First generation stars are stars that are formed from big-bang gas - mostly hydrogen, a bit of helium, a trace of lithium, and nothing more. Second generation stars are formed from the gasses blown off by the novas of first generation stars. Third generation stars are from the novas of second generation stars.

I suspect that the claim that life as we know it can only evolve there is because life as we know it needs a wide variety of chemical elements. We need carbon and oxygen, of course, but also iron and calcium and magnesium and potassium and so on. You're not going to get that around a first generation star. You might not get enough of it around a second generation star.

Familar higher orders of complexity emerge far easier within systems with more states.

Due to our physical laws elements with larger rooms for reaction via chemistry are familar.

The chances of a replicating agent just anthropologically emerging from the surface of a 2nd generation hydrogen dominant star with an accumulation disc composed of little higher orders elements is inconceivably less likely than the relative petri dish organic molecules provide.

This is my belief as well, although slightly different in how I phrase it: humans are incapable of seeing much beyond their own selfish desires, and as a result will wind up causing their own extermination. The denial of death is widespread and understandable: to truly consider existential demise is exhausting, and I suspect has been backgrounded for simple evolutionary reasons.

Regardless, the species is naturally incapable of averting averting crises that are foreseeable but distant.

For every planet with intelligent life, there could be many more without it, no idea what that relationship might look like. I'm not suggesting it's the norm.

See also https://en.wikipedia.org/wiki/Great_Oxidation_Event.

> Such negative values occurring shortly after the GOE require a rapid reduction in primary productivity of >80%, although even larger reductions are plausible. Given that these data imply a collapse in primary productivity rather than export efficiency, the trigger for this shift in the Earth system must reflect a change in the availability of nutrients, such as phosphorus. Cumulatively, these data highlight that Earth’s GOE is a tale of feast and famine: A geologically unprecedented reduction in the size of the biosphere occurred across the end-GOE transition.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6717284

A MAD weapon like that just becomes an AD weapon. A nuclear lab leak kills under 1,000 people. A living weapon lab leak would kill (nearly) every other living thing.

> because nothing can eat them

But I assume they're not immune-invulnerable.

I'm getting similar vibes to out of control gene drives created with crispr...

I believe if you look at their genetics they fit snugly within the tree of life

tardigrades might have some very cool properties, but nothing out of the ordinary.

The book 'Evolution' by Stephen Baxter.

Wikipedia article here: https://en.wikipedia.org/wiki/Evolution_(Baxter_novel)

Evolution by Baxter

There are no real infinities. The universe might be infinite, but the bit of it we can see and/or ever interact with is not (speed of light + expansion). So there are a finite number of stars that we will ever be able to touch before the universe goes dark. And the universe seems to have had a finite starting point. So we can calculate which stars may ever reach out to us. These are very big numbers, but they are not infinite.

Unless star trek is real. Faster than light travel opens up the door to infinities.

Why not beam yourself into a meatsuit over the internet?

It has no realism at all. Why would an organism with no experience of Earth environment outcompete life evolved to it?