Alien Worlds.... Alien Elements?

[Bab5space]

The perodic table we learn in school. All the stuff on it is found on Earth, and some of it (not all of it) we can find on other worlds.

So it got me thinking, what about alien scifi worlds?

Unobtanium is a common scifi trope, and all too often scifi humans envy aliens having unobtanium.

But I thought it can and should... go both ways.

What I mean is... yeah, aliens might have power crystals that take months before melting while emitting fusion level energies.

Yet they may lack uranium and plutonium, and may have never made a nuke before. So they might want to trade their crystals for our uranium.

What kinds of unobtanium tropes could in theory be possible?

High energy yielding power crystals?

Superconducting magnetic liquids?

 

[anorlunda]

What kinds of unobtanium tropes could in theory be possible?

You are asking a contradictory question. What impossible things are possible?

 

[essenmein]

What kinds of unobtanium tropes could in theory be possible?

As @anorlunda said, you are asking what imaginary things could you imagine.

However you might want to consider where on Mohs scale you want your story to sit, for a somewhat entertaining read, and links to piles of other info:
https://tvtropes.org/pmwiki/pmwiki.php/Main/MohsScaleOfScienceFictionHardness

 

[Janus]

Basically, the laws of physics apply the same everywhere. The same elements possible on the Earth will be possible on another planet. We've filled the periodic table up to element 118. Any "new" elements would have to have larger atomic numbers. The problem is, only the first 94 occur naturally, the rest had to be synthesized in particle accelerators. They also have short half-lives. While it is suggested that an "island of stability" might exist for higer atomic number elements, it really would just be an island of relative stability. Elements there would still be unstable, it just that their half-lives would be a bit longer than that for elements to either side of them.*
While another planet might have different concentrations of certain elements, And you might find a planet lacking in higher elements, You are not going to find one that has different elements to take their place.

The power crystal you mention would have to be a synthetic product of their own making. In other words, they would have had to have knowledge that made it possible to make that we don't have, and it would not have been a natural substance.( It also very likely is impossible to even synthesize.

If you try to assume that the laws of physics are completely different on that planet in order to allow such a natural substance, then it would be useless to us. If we tried to bring it to Earth, it would just quit working as our physical laws wouldn't allow for it. For that matter, even visiting the planet would not be a good idea, as the laws of physics there would not likely be the same as those needed to keep us alive.

* For a long while, and before it was actually synthesized, many UFO proponents claimed that alien spacecraft used element 115, which had unusual properties, for propulsion. When it was actually made, it turned out to be not unusual at all.

 

[Vanadium 50]

For a long while, and before it was actually synthesized, many UFO proponents claimed that alien spacecraft used element 115, which had unusual properties, for propulsion.

A miscommunication because our alien friends have 12 fingers.

 

[member 656954]

Modesitt Jr. explored this concept in his novel, The Eternity Artefact. It's an excellent story on a number of levels, including being a masterclass in how to write clearly differentiated first-person points of view from multiple characters so each has their own distinct voice.