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Comment by harshulpandav | Hacker News Reader

I wonder why many people visualize aliens to be entities with flesh or something else like how species (that move or grow) on earth. I think aliens can also be in the form of new elements, rocks, gases, waves, or some entity which is beyond the ability of 5 senses of humans to perceive. Currently we use other methods to transform perception of entities so that humans can see/feel/hear/understand. But the devices we build for this purpose are built using earth elements. It could also be probable that earth might not be having those elements which are required to give humans the ability to perceive other entities.

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Well, chemistry has some pretty good evidence on which elements do and can exist. I don't think we'll be seeing unknown elements (sorry Mass Effect) any time soon.

And if they exist beyond what physics can currently detect, then the point is sorta moot.

Not unknown periodic table elements, but new minerals, possibly formed in conditions not found in Earth, yeah

Chemistry would suggest we've found all stable naturally occurring elements too.

BUT I will say that there is extremely good evidence that there are plenty of unknown elements (I'd argue that every chemist agrees). Well, more accurately, elements we haven't created. Feynman says the limit is 137, but others think it is higher (relativistic limits). The thing is most of these are unlikely to be stable, though there are some predictions for stability in the 120's.

But to be life, they would need to be stable. And it would be EXTREMELY odd for life to be made from non common and non naturally occurring elements. Even more odd to be from unstable ones.

It's exceedingly likely that any new elements we discover will have half lives fractions of a second and not available anywhere in the universe other than the labs of civilizations at least as advanced as us. So there's almost no possibility that they play any role in alien life.

Well there are predictions of islands of stability[0] in the 120's (and further) because magic numbers[1]. But no one agrees on how stable those are (milliseconds or MUCH longer). And I do want to mention that I did suggest that these elements would need to be created in labs.

>> Chemistry would suggest we've found all stable naturally occurring elements too.

Because these elements are trans-uranium. IE: Man made.

> So there's almost no possibility that they play any role in alien life.

>> But to be life, they would need to be stable. And it would be EXTREMELY odd for life to be made from non common and non naturally occurring elements. Even more odd to be from unstable ones.

Read "odd" as "highly unlikely and unexpected".

I'm not really sure where we're in disagreement. Except for the island of stability part. But that's why I said

>> most of these are unlikely to be stable, though there are some predictions for stability

We don't know if they are stable or not yet. Because we haven't made them. And I am making ZERO claims that there are. But I am making claims that there are predictions of stability. Which is trivially verifiable.

[0] https://en.wikipedia.org/wiki/Island_of_stability

[1] https://en.wikipedia.org/wiki/Magic_number_(physics)

I think there is more to life than just flesh and senses. Fundamentally, what makes living organisms "living" is the DNA (in primordial soup, it was RNA). Self-replicating systems lead to evolution almost magically... spontaneous processes (that minimize energy and are driven by thermodynamic imbalance) tend to create "competition" as they use up resources. The ones that make barriers or membranes, can protect the resources and end up replicating in larger numbers or faster.

We know that Carbon is essential in creating these self replicating entities. Its abundance is also known in the universe. So, it is not so unrealistic to presume that aliens won't be something that we can see on earth. I am curious of the differences of the forms of life that can originate though.

Imagine if we rerun 2 billion years of evolution again with a different initial conditions. Surely, we'd have different forms. Contrarily, eyes have evolved independently in many organisms over a dozen times. So, there is some commonality there. Just like the eye, there are many similar biological processes that evolve independently (arteries/veins, neuron, heart for circulation/extraction, ceramic structural components/bones, etc.)

I used to think about the same question that you are also wondering but the deeper you go down this rabbit hole, you are realize the importance of why things in living beings are the way they are. They're solutions (however imperfect) to an evolutionary problem.

> Contrarily, eyes have evolved independently in many organisms over a dozen times.

I'd argue that this is because we all have the sun in common. On a planet that orbits a star with a different spectrum or a planet that has a different atmospheric makeup, "vision" might look very different to what we're used to.

Why would DNA be essential? Why limit "life" to just carbon-based lifeforms?

It could be another self-replicating entity. It doesn't have to be DNA. But self-replication is the __basis__ for evolution of life. Sure, it could be made from other elements...but why wonder if other elements can create self-replicating entities when you can measure the amount of Carbon in the galaxy...right from here on earth! Carbon is more abundant than say Strontium. Carbon is created inside a star, Strontium is created through Supernovae explosions.

Also, Carbon can form 4 covalent bonds more easily than Si (same family). Si can form 4 covalent bonds but they're weaker than Carbon due to the distance from the nucleus. I am sure someone more familiar with Chemistry can chime in, but Carbon is a special element in the Universe.

Indeed carbon is special in this regards it's also produced in star fusion and space is filled with organic material because carbon, oxygen and hydrogen are abundant.

Also the main reason why silicon is worse is because of catenation, which carbon is much better suited for: https://en.wikipedia.org/wiki/Catenation

Thanks for adding to the discussion. I learned something new.

You were right it's because of the covalent bonds formed, however the biggest difference seems to be not in how these are formed with other elements but how carbon is essentially optimal at bonding with itself creating huge chains.

This property is why there are so many different and interesting forms of elemental carbon.

These chains are the scaffolding for all biochemistry both because they are very stable and also because they have very interesting properties.

Chains can be either open or closed depending on various factors such as charge, temperature and other forces that play on molecular levels allows you to play with that geometry.

Having strong chain bonds not only builds stable chains but it also build chains that can change their state while remaining intact and biochemistry heavily relies on the ability to change the geometry of complex molecules without breaking them apart.

Because of physics.

Life may also come in the form of a group of "artificial" robots that can mine and manufacture copies of themselves, with AI that can learn and teach each other.

Such "beings" (and indeed they should be indistinguishable from "natural" beings given a few hundred years) wouldn't need to evolve from scratch, so they don't necessarily have to be mostly built from basic elements like carbon.

Depending on who you read, life could be quantum wave functions flying around the universe, or even dark-matter "birds" slowly tearing suns apart.

I may read too much sci fi.

Yes, the fight between Baryonic matter and Dark matter does promise to be quite the show: https://en.wikipedia.org/wiki/Xeelee_Sequence

Good point. If you haven’t read “They’re Made out of Meat”, you’ll find this short story very amusing:

http://www.mit.edu/people/dpolicar/writing/prose/text/thinki...

There's a short film adaptation of this as well: https://www.youtube.com/watch?v=7tScAyNaRdQ

Michio Kaku certainly argues for existence of aliens in the higher dimensions than our own-4th dimension has time element, all the way up to the 11th.

In fact he argues that it's possible that these higher dimensional beings figured out how to travel between universes (if you follow the multi-verse theory) by heating up to an insane temperature point where it rips a hole in the space-time fabric, allowing for the said civilization to continue living in another universe where it isn't collapsing.

To me the Minot airbase incident is the most telling based on all 20 something individuals that witnessed the same events where light orb like things deactivated the nuclear silos.

This suggests that the nuclear tests basically triggered a radar somewhere deep in space by said advanced civilization, then suddenly you have a spike in UFO sightings.

I think this scared a lot of people at the top, because their power base is directly threatened by an advanced adversary that has technologies far beyond your own, want to keep hush hush so they mix lot of hoaxes to make it impossible to distinguish real from fiction (a classic disinformation strategy with tall tale markings of tradecraft also used by Soviets).

What's even more strange are both USSR and US encounters with UFOs and the same type of hush hush, namely the Phobos satellite which was 'decomissioned' by a similar looking object found during the initial Apollo moon landings, which is riddled with censorship, including what appears to be unnatural and regular structures and objects you can observe with a powerful telescope (check out https://youtu.be/3xiJnDuVOFA?t=2m12s)

Just watch Unacknowledged on Netflix....it was frankly eye opening.

say what you will but the fact that US Navy released the UFO video captured by F-18 IR radar, the announcement of a "Space Force", it's all obvious that the next bogeyman won't be communists or terrorists but extra terrestrials....this is the ultimate logical conclusion one can make based on the following core belief that tests one's affinity for trust in higher institutions formed by humans.

Because carbon has the richest chemistry, making it the most likely basis for life:

https://blogs.scientificamerican.com/lab-rat/shine-on-you-cr...

We can detect elements in other star systems. Earth elements are pretty standard, it turns out. Interesting idea though :)

We like to start small, then think bigger later

Like roentgenium and basalt might be aliens?

Ghost..is the word you are looking for.

I completely agree. It's all we know so we don't think about it as humans but we have very limited sensory organs. We can only see like 0.0035% of the light spectrum, out sense of smell is nothing compared to what a dog can smell, and we can't even sense magnetism!

I imagine watching humans do technology from an aliens perspective is like us watching a chimpanzee use an iphone.

Actually we can see 100% of the em spectrum, we have tools and instruments, in fact that is what separates us from the chimpanzees you mention. Give your species a little credit.

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