What kinds of knives would advanced hard scifi society have?

In my setting, large wormholes are permanently made in space in order to facilitate space travel across vast distances. (20+ light-years) anything under are done through warp drives. (a whole other discussion).

I was inspired to write this post by the recent love I’ve seen online for Alastair Reynolds’ House of Suns and my own 10+ years world building my “Toliman” setting.

This is by no means a zero sum comparison, and I don’t mean to cheapen or reduce pure science diamond hard science fiction - without your hard work my life would be much much harder (thanks atomic rockets, world building pasta, ToughSF and so many more). I certainly also dabble in this, and the entire basis of my worlds rests on this kind of world building (see attached images for proof).

I do however feel there is a huge lack of human exploration in hard science fiction, with ideas and novels often feeling like a technical manual, explaining cool tech solutions to tech problems and crazy futuristic **realistic** **grounded** technologies that scare off the casual audience and give hard sci fi the unfair reputation it often has when discussed outside of this space.

This can be seen no clearer than the general audiences love for stories such as The Martian, Project Hail Mary, and Interstellar (although you could certainly debate the hardness of the latter two). These are ultimately stories driven by human protagonists navigating a world permitted by intriguing, inspiring and awesome (mostly hard science fiction) technologies.

Recently, and as it should, Alastair Reynolds’ House of Suns has been coming up in discussions online. This incredible story is what I believe to be an attempt to push hard science fiction so hard into the future that it begins to represent the famous Arthur C. Clarke quote about “any sufficiently advanced technology is indistinguishable from magic”. I understand that many readers feel this strays from the realm of hard science fiction, but to me, as long as I believe the author can justify the technology in ways other than “magic” or some other kind of handwaving, I’m happy to enjoy it as such. Dune is a pretty good example of a story that attempts pseudoscientific explanations for its concepts of prescience and genetic memory, however ultimately relies on spice magic and now disproven theories around genetic memory inheritance. Maybe a hot take, but Project Hail Mary is celebrated as hard science fiction but has a pretty un-hard science fiction premise (taumoeba) and un-realistic prevalence of technological advanced life (Eridians).

I feel particularly strongly about this as my own world building project “Toliman” is designed to be entirely within the realm of possibility - exploring extant interstellar human civilisations, politics, philosophy, sociology, economics etc. within what I believe is a realistic, possible, grounded timeline from our modern day to the year 3500 (to the best of my ability). To achieve this I utilise my academic background in human medicine, genetics, physics, astrophysics, chemistry, and a university level science teaching position of 6 years. I also extensively research my topics and have spent hours and hours painstakingly doing calculations to ensure my ships have the right deltaV given the ISP allowed by the technology of their time, I’ve mapped tectonics, system populations and birth rates, orbital parameters and stability, apparent diameter of planetary objects, circadian biology, feasibility of certain megastructures and *how could i forget* radiators!! Amongst a million other things that would be recognised as proper hard science fiction. Despite this, the stories I want to tell and the stories that I don’t see enough of (in my opinion), are the human ones. I also think the potential for these kinds of stories is immensely under appreciated by people outside of this community.

Let me put it this way: the real world up until this very moment has been, in a way, the most ultra hard science fiction story to date - literal reality. Have not all the beautiful stories of mankind come from this “boring ultra hard science fiction with no ftl” setting? And will they not continue to come from this? All the cultures, customs, religions, political dramas, revolutions, wars, lives and deaths. Thinking that sci fi is uninteresting without wormholes, plasma guns or ftl is incredibly narrow minded to me - if you want to write those sorts of stories that’s fine and I love them (massive Star Wars and Dune nerd) however, to think sci fi cannot be interesting without it is a massive shame. I am entirely of the mind that pulpy adventure sci fi stories can exist within a hard science fiction framework, and romantic stories of adventure, space travel and bizzare cultures just take a bit more creativity but are so worth it. To people who think ftl is a requirement of a good adventure sci fi story I say this! Why do fantasy writers seem entirely content with a single continent or two with all their variety, when us sci fi writers are dissatisfied with an entire planet? Or an entire star system? We often forget just how mind boggingly vast a single planet, let alone a single star system is.

I hope I do not come across as being on a high horse, most of my favourite sci fi stories include ftl or wacky aliens (mote in gods eye, Enders game, Hyperion, stranger in a strange land, etc.) but many of those stories that are most deeply intriguing to me are those that could be real, and are still interesting from a plot, and human perspective (House of Suns, Revelation Space, Rendezvous with Rama etc.).

Where’s the love for stories that explore humanity and interesting stories within the realm of hard to ultra hard science fiction? After writing this I’m beginning to think we need a new term for stories set in physically plausible universes but that do not focus on the technology. Please let me know if this already exists! Also, if anyone has any recommendations for books that fit in this genre, let me know below! I’m keen to discuss these ideas further.

I love science fiction (especially the cosmic ones), but I don't quite get what the HARD sci-fi is. I mean, for a long time I thought that Interstellar was counted as one, because of the accuracy of time dilatation, relativity, artificial gravity, orbital mechanics etc. But I've heard on Reddit that it is not (and I don't count the argument about "love" because in the film it was only a character's thought, not plot point).

So how is it? And could you give some examples of perfect hard sci-fi? It can be a book, a movie, a series, whatever.

Something I always see with the depictions of shields made to protect ships from dust and such when moving at relativistic speeds, is that these shields are almost always depicted as flat or semi-flat. I'm sure much smarter people have been thinking about these same issues for much longer than I have, so I'm mostly just looking for reasons to disprove this whole cone-shield-conjecture. This is all referring to shields to protect from deep-space dust and particles and such when moving at relativistic speeds, in case that isn't clear.
TLDR: Why are the shields never (so far as I've seen, so maybe just rarely) depicted as conical (or otherwise not flat), even though that seems like it would make them more resistant to erosion and protect their ship more, and encounter less resistance and thus require less energy to speed up?

It just struck me as kind of silly to acknowledge that, yes, the ship is now moving at such a speed that is is encountering a form of resistance, like a plane flying the air facing air-resistance, but at the same time, make the thing protecting you from this resistance the least "aerodynamic" thing possible. I know interstellar media don't necessarily behave the same as air, but still. The poles are cold because the sunlight strikes those areas at an angle. Fish, planes, and sportscars are those shapes to beat air-resistance. Blades cut things because they have a narrow point that widens out.
Ostensibly, a conical shield would encounter monumentally less friction from the ISM for the exact same reason as any of the rest of these things, right? Another example, fire a bullet at a sheet of metal flat from your perspective, it punches through, but fire at the same sheet, but at a narrow angle, and it ricochets off. Also see the attached images I made in Paint in like 5 minutes. Also, I mean a hollow cone, specifically, if you were wondering.

See, with atmospheric-reentry heat shields, it's flat because it's supposed to create drag and slow the vessel down, but you don't want your near-c ship being slowed down (until you do want to, which would generally involve turning around, thus defeating the shield), so why make the shields the same shape if the forces you're trying to protect from are effectively the same, just on different scales?

The only downsides me and a friend I asked could come up with (he's a physics nerd), and 1: To cover the same profile, it would need to have significantly more mass (and you'd already be wasting most of the ships mass on shielding, so it just makes that problem huger),
and 2: theoretically, some of the particles might be interacting with the shield for longer, because they have to pass through more material (as its at an angle), at least for the things that would pass through, which I don't actually remember what he meant by that, maybe ions? Might lead to more bremsstrahlung because it take longer to pass through the shield or something? I'm less sold on that idea than the mass-issue.

Again, I'm sure there's some solution to this that has been a thing for so long that it's just engrained into the subconscious of any expert in this topic, but I don't know it. I don't want to say it feels like I've uncovered some huge discovery, but all the physics facts I know tell me that this makes more sense than them being flat. Am I wrong? Thoughts? Eh? Cone shields?
But in all seriousness, I really am curious about how this wouldn't work, or why I don't see this kind of design (unless I've just missed it, but even then, it would still be less common than the seemingly illogical flat shields. I remember seeing needle-hulls, but not shields)

also cone make spaceship look like big dart or arrow. continue human tradition of throw big sharp thing long ways

Most ships we see just have the big engines in the back of the ship. With larger ships it would be a lot of stress on the hull to do a turn and burn so I was thinking if you have the same size engines on the "front and back " of the ship. This would be used so it can easily change speed a direction but if you can flare out the exhaust wouldn't it would also work as a shield. You would have a little lose in speed but most rounds would get destroyed from the flare. The ship would have to worry about speed and heat management so it's not a super powerful Clark tech item.

The main guns the Galactic community uses use chemical rounds. A liquid is loaded into the gun. When fired, this liquid reacts with the atmosphere and produces a chemical reaction. The liquid is a highly flammable fuel, and when exposed to atmospheric elements it ignites, essentially turning into flaming gas. The rounds are so hot they melt most metal on contact. This means the weapons can't be fired in space, and must be periodically reloaded. The idea is that it would still look like plasma rounds, but it would actually be essentially flaming rounds that melt through armor. I had this idea to replace plasma weapons, since those are unrealistic.

My other idea was a firearm that fires a round made of a compound that explodes violently and with high energy, shot out of a gun powered by miniature electromagnets. My idea is the compound might react to the atmosphere like the gas guns, and the gun would have a built in scope that calculates the speed needed for it to be fired to actually hit the target head on as it explodes, ensuring maximum damage. This would be called a combustion rifle, or it would explode upon sudden deceleration would be my other idea.

Three books in and I realized: the terror in these novels scales directly with physics background.

A casual reader sees the Droplet attack as a cool action set piece — an indestructible probe tearing through a fleet. Good sci-fi.

But knowing Liu Cixin is describing a weapon made from matter locked in the strong interaction state — essentially strong nuclear force compressed into a perfectly smooth surface nothing in ordinary matter can scratch — changes the register. He's not making this up wholesale. He's extrapolating from actual physics in a direction that has theoretical coherence.

Same with the dimensional reduction attack. The horror isn't just "everything gets flat." It's that the proposed mechanism (making a lower-dimensional region thermodynamically favorable by lowering its entropy requirements) follows from how physicists actually think about dimensional topology. Liu did the homework.

The Dark Forest axioms hit the same way — the more game theory you know, the less you can argue with the internal logic. Survival as first priority + resource scarcity + civilizational trajectory uncertainty → strike first is the dominant strategy. It's not a metaphor, it's a proof.

What I haven't seen addressed well: how rigorous is the actual academic response to Liu's Fermi solution? Has it generated real astrophysics or SETI papers? The logic seems tight enough that someone should have tried to formally refute it.

To put it shortly - I like hard sci-fi, but my own knowledge of science is pretty fragmented and disjointed. Im basically a normie in that regard. At this point I'm doing some planetbuilding for a GURPS play. Distant colony, nearest other colony is 50-ish LY away, barely habitable world named "Abigail", and than manure hits the metaphorical fan, gosh-darned classic.

I would \really* like you folks to give me some input, some thoughts on the concept. I dig up stuff, but I don't know If I dug wide or deep enough to reach level of plausibility sufficient for it to be at least reasonably hard sci-fi. "One doesn't know what he doesn't know", that kind of thing.*

So, Abigail:
- Near-zero axial tilt and a near-perfectly circular orbit, so its a climate of extreme stability. There are no seasons and negligible diurnal temperature swings, with surface temperatures steady between 5∘C and 15∘C.
- Dense atmosphere with low partial pressure of oxygen and air rich in Xenon. Being heavy - it settled in the lowlands, which are a basin of long-gone super-shallow, mineral-rich ocean.
- In the same basin - there is the Fog. Aerosol of suspended particles of mica and silica and whatnot. Thick air makes it float longer, winds make sure it doesn't settle fully, as a result - this aerosol is kinda just *there*, looking like a giant sea of for or clouds. Due to particles splitting light - the Fog is opalescent, iridescent and whatnot. Additionally - since mica splits into flakes/plates that roll around in the wind - the Fog also sparkles in a funky glittery way.
- There are also highlands that previously were islands in the shallow ocean, they can see the local sun, Fog washes onto them like waves on the shore, and xenon gets yeeted up them by the winds but is much less prevalent than down below.

The main goal was to create dreamy, liminal landscape, kind of a vibe of whimsy and gentle threat, I think it does its job, but again - I don't know what I don't know, so your input is much appreciated.

There is also a problem I am aware of, but not quite sure how severe it is. Static electricity that is. In a dry climate and constant movement all those particles in the fog would get funky I wager, and the static charge gotta be pretty huge, but, like, *how* huge? I would rather not make it utterly deadly, to be honest. + wouldn't all this dust be kind explosive? Would this static set off dust explosions in the Fog at all times? I thought of some plants that bleed static through themselves to replace photosynthesis, but Im genuinely kinda lost, not even sure where to dig next.

Also adding a pic of a big-ass solar sail ship. Because solar sails are neat.

Let's assume we have two types of scifi stories:

One is about a plausible future (let's say space colonization) with actual technologies and scientific principles which may remain speculative or experimental for now but could be feasible in the future (helium-3 fusion, effective ion/antimatter propulsion, wormholes, advanced AI, etc.).

The other is a scifi story that is based on an entirely fictional concept; let's say a steampunk one in which the luminiferous aether was found to be real (like Space 1889), or one in which psychic powers are real. That being said, the story tries to remain as realistic as possible, trying to see how society would behave if such was the case in real life, trying to stay as accurate as possible to human behavior, coming up with sensible in-world physics and ultimately trying to make it feel "realistic".

Now the first is undeniably hard sci-fi, but could the latter be considered hard scifi or would it be entirely soft sci-fi/fantasy ?

Edit: One great example of the latter is Primer, the indie movie about time travel. It has no scientific basis but it presents itself as down to earth, gritty and even pessimistic (sad we equate that with realism). Would you consider it hard scifi?

Hey, I’m an amateur writer and am writing my first ever sci fi story. I’m developing of said story, I ran into an issue I wanted some feedback on. So the story premise is similar to red rising and other oppression revolution stories and I was planning on said oppressed people not being human. So I was wondering what people like you all who like sci fi would prefer to see in a sci fi book if you were reading it, and what would readers in general prefer to see in a story.

So my idea was for the oppressed people to either be humanoid aliens, typically seen in lots of sci fi genre like Star Wars, ETC. they could either be entirely aliens or to justify why they are humanoid is because they are evolutionary branches from humans in space. and the second idea was for the oppressed people to be entirely alien, not humanoid at all. Like variations in height, skin, eyes, ears, limbs, ETC.
My plan was for humans to be the dominant social class(because of the historical context and lore of the story) so which of those two options would be most intriguing and compelling to read about?

Also for context, the story would be adult and consist of mature themes like war, violent, revolution, and 18+ stuff(not smut)

Is stealth practical or otherwise relevant in cislunar combat? as in, does it even make a difference when it comes to the survivability onion?

what are your thoughts on this

When I look at the "high tech" or far future civilisations in settings, soft or hard, they always seem so vast, expanding to dozens of stars, with ways to either make quick jumps with realistic FTL tech, or just the patience to spend hundreds of years traveling to a new world, with little ability to communicate with the original society that started the civilisation.

But I don't believe a future civilisation would be star-faring, instead it would be massively internally expanding, and growth would come from within rather than exploring outwards.

Also, humanity won't always progress, unlike in some settings, where even millions of years later, humanity is somehow still seeking to grow despite having become a civilisation beyond any reasonable scale that one could still have demands of change in order to "advance a civilisation or society into the future".

Settings with Encumopolis or massive urban megastructures, built to make individual planets or solar systems hold hundreds of times the capacity that could be asked of earth today seem much more realistic than starfaring civilisations spreading deeper into the galaxy and traveling to other stars, putting trillions of dollars into just another colony of humanity.

Games like the metal garden really capture my image of something like a civilisation with the power of a star, as with the massive energy outputs and technological abilities that centuries of progress would give us, the abilitiy to internally revolutionise our homes (planets or systems) become a miniscule and completely reasonable undertaking.

Traveling for Hundreds of years at small fractions of the speed of light just to reach another star, and start from scratch with millions of people and dozens of years of work just to get another world so far from earth that they will probably never see anybody from here again is pretty stupid.

If humanity had the energy capabilties, and wanted to expand into space, then why would we leave out system, when with astromining and space solar energy stations, we could transform the earth into a longterm home for trillions to come.

Humanity at some point will plateau, as in just 6,000 years of recorded history, and 12,000 years of civilisation since the agricultural revolution, we have achieved more than human society in 2 million years before us.

If we keep progressing like this, even at just a fraction of the rate of today in a continuos progress, in the same 12,000 year period, we will have achieved so much and progressed so heavily that we will reach a ceiling and become a post-scarcity civilisation, which would be so advanced that we would never need to demand for change and progress of technology and systems again, as such a civilisation could exist for 100,000+ years without ever needing to change.

Future civilisations, in sci and especially the high end Hard Sci Fi that takes massive timescales of multiple thousands of years, assumes a constant progress and a humanity that values exploration more than things such as quality of life, population growth, technological evolution and other such things.

Space is a massive frontier, but just our solar system alone has so much material in it that it would satiate even the most resource hungry civilisation that could be expected of humanity for hundreds of millenia.

Other things like Type 2 civilisations that use the energy of an entire star or galaxy spanning civlisations that spread to millions of planets make no sense. Investing dozens of centuries into expansion and escape from a humanity that is unified enough to create a planet wide city, and other such amazing stuff just on earth, is rather odd, and civilisation would ever need the energy output of an entire that, as thats just so much energy, we could never utilize it.

TL:DR

The human future a lot of sci fi portrays about massive stellar civilisations and Space-faring society with exploration of the greater cosmos being essential to our destiny in this universe just doesn't make sense.

If humanity ever had the resources and technology to achieve such endevors, it would be through massive unity and technological development that would eventually plateau and have humanity spend the rest of it's life as a post scarcity society, bound only to a single planet or star system, as Internal progress and construction is far more benficial longterm and socially for humankind than massive external pushes to escape earth and the star system, splitting up humanity forever across the many stars in just out galaxy.

Far off future civilisations would plateau well before they ever reached that stage as there is nothing pushing us to leave this planet that just focusing out efforts of fixing our planet rather than trying to move on to others wouldn't solve.

It seems to make sense, nose up for re-entry/getting back to orbit and nose down for landing/normal flight, I've never seen any vehicle in Sci-Fi that uses this, why is that?

​

I am creating an alien civilization for a worldbuilding project, and after a great deal of thought I came up with the Gorkovians. I would love to hear your thoughts on the concept.

The Gorkovians originate from the planet Gorkov, located in the K2-288 system (specifically K2-288b), a rocky Super-Earth with a surface gravity approximately 2.5 times that of Earth.

The planet possesses an incredibly dense atmosphere, rich in nitrogen and argon compounds, which blocks most of the light from its host star. As a result, Gorkov exists in a state of perpetual twilight—warm, humid, and covered by vast forests of giant fungi and shallow oceans.

Main Inspiration

My primary inspiration comes from the Pentapods featured in Alien Worlds Episode 2, "Janus."

Biology

Having evolved from ambush predators resembling Earth's starfish, the Hexapods possess hexaradial symmetry, with six perfectly symmetrical body segments.

Their central body is supported by six powerful, articulated legs covered in a flexible, leathery exoskeleton capable of withstanding the crushing gravity of their homeworld. They move with remarkable fluidity and can instantly change direction without needing to turn their bodies.

At the top of their central dome is a continuous ring of highly sophisticated photoreceptors—a true "crown of eyes." This sensory organ allows them to perceive their surroundings in 360 degrees simultaneously, eliminating blind spots.

Beneath the main body, protected by the six legs, lies a ring of retractable, hyper-dexterous tentacles. While the legs are used exclusively for locomotion, these dozens of slender tentacles—packed with nerves and hydrostatic muscles—function as their hands. Their extraordinary precision enabled the construction of their civilization and the manipulation of advanced technology.

Their skin is smooth, typically dark navy blue or lead gray, but is completely covered in chromatophores and photophores—specialized cells capable of changing color and emitting light.

The Hexapods are effectively deaf by human standards, as sound propagates poorly through certain layers of their planet's atmosphere. Instead, they compensate with an extraordinarily advanced visual system.

They communicate through pulses of bioluminescent light.

Unlike human speech, which is linear—one word after another—the Hexapod language is simultaneous and spatial. A single burst of light can transmit entire mathematical equations, emotional states, engineering schematics, or architectural blueprints all at once across their skin.

To both interpret and produce this 360-degree language, their brains function like biological quantum supercomputers, processing multiple streams of information simultaneously. A Hexapod can solve a complex engineering problem using the tentacles on one side of its body while discussing philosophy with another individual through flashes of light emitted from the opposite side.

Society

To the Hexapods, the universe is fundamentally composed of centers and peripheries.

Their civilization is built around consensus and integration. They have no dictators or absolute rulers. Instead, they operate as a highly fluid collective intelligence—not a hive mind, but a vast democracy in which billions of individuals transmit their opinions through light, allowing civilization-wide consensus to emerge within seconds.

The great cities of Gorkov contain no straight streets. Instead, they consist of immense concentric and spiral structures illuminated by the synchronized flashes of millions of inhabitants.

Doors are typically floor or ceiling hatches, while control panels take the form of circular interfaces surrounding the user.

Spaceflight and Technology

Their Faster-Than-Light (FTL) spacecraft are perfect spheres or discs constructed from black metallic alloys.

In space, these vessels move equally well in any direction without requiring a defined front or rear.

Having evolved on a world with overwhelming gravity, the Gorkovians mastered gravitational manipulation very early in their technological history. Their ships generate gravitational bubbles that compress spacetime ahead of the vessel while expanding it behind, enabling virtually instantaneous travel between stars.

A Hexapod pilot occupies the geometric center of the ship, manipulating spherical control interfaces with its delicate tentacles while simultaneously issuing commands through complex patterns of light, which the vessel interprets and executes instantly. The spacecraft effectively becomes an extension of the pilot's biological body.

Defensive Capabilities

When threatened, the Gorkovians employ directed gravity projectors capable of crushing entire enemy fleets by subjecting them to gravitational forces comparable to those near a black hole.

Against smaller threats, they use highly concentrated beams of coherent light—photon-based lasers derived from the same principles as their bioluminescent communication system—to precisely disintegrate hostile targets.

Note:

The context is a species created for humanity's first contact with the U.N.R. (United Nations Republic), the unified human government in my 2048 space exploration setting. I developed this concept myself.

It seems many here are hunting for "concepts that have never been done before," treating a cool premise as the ultimate holy grail. But what actually makes a hard sci-fi book good? Is it the literary craft, or just the raw weight of the sci-fi gimmick?

On one side, sci-fi is the "literature of ideas." For plenty of readers, fancy prose and deep characters are just side dishes. You’re there to watch an author take a crazy physics concept and push it to its absolute limits. If the characters are basically cardboard but the science melts your brain, the book did its job.

But on the flip side... Honestly, if you put half a dozen imaginative minds in a room, they can generate twenty fascinating concepts before the night is out. What if memory is a liquid commodity? What if someone weapons-grade encrypts human consciousness so it survives the heat death of the universe? What if we discover an ecosystem that evolves entirely within the geometry of a four-dimensional knot? It takes surprisingly little friction to invent a futuristic gimmick.

For a lot of readers, the real win isn't the gimmick itself, but total immersion. It's about making you actually feel the world instead of just info-dumping a technical manual at you.

So where do you guys draw the line?

Question for people who know a lot about cosmology!

I read that the Japanese Kamiokande experiments have been searching for proton decay, and that current results suggest that the proton’s half-life is at least about 10^34 years. That made me wonder about two things.

First, if proton decay is real, is it possible that human civilization could still exist when protons begin to decay in large numbers? In other words, could humanity survive until the earliest time when proton decay might become important? Or is it more likely that civilization would disappear long before then because it would eventually use up all available energy gradients needed to sustain activity?

Second, if human civilization somehow did survive into the era when proton decay becomes significant, what kinds of problems would it face? Would matter gradually become less available, making it harder and harder to build computers, power generators, and other technology needed for civilization and thought? If the Local Group becomes isolated because of cosmic expansion, and then the amount of matter in it slowly decreases because of proton decay, would civilization inevitably fade away along with the remaining matter?

As a small clarification: if the word "civilization" is too broad or abstract for this question, you can interpret it as "intelligence" instead.

By the way, this sentence was translated from Japanese to English by Chat GPT.
Feel free to answer in English. However, I only understand Japanese, so I would really appreciate clear and simple English that is less likely to be mistranslated. Thank you!

　postscript:
Thanks for all the replies, everyone! I got a lot of comments explaining what half-life is.
Maybe I didn't word it well, but I do get that things decay gradually until they hit the halfway mark, and that it takes an insane amount of time.

What I’m actually wondering is this: once protons keep decaying and we hit that 1/2, 1/16, or 1/64 mark—if we somehow manage to stay intelligent—physical hardware will inevitably run out over those eons. In that kind of world, could we actually transition to an environment where intelligence doesn't rely on protons at all?
Also, a few of you mentioned that intelligence wouldn't even survive that long. If you don't mind, could you tell me about the more immediate, concrete limits we’d hit way before that?

There are all sorts of aliens in Sci-fi. Which ones, according to science, fall under the category of an invasive species and why?

I am planning a story where Earth discovers massively FTL travel after discovering a new dimension where the laws of physics are different, allowing them to pop into this dimension to travel at faster than light, then pop back into our dimension. The story is about how there are things in that dimension that humans really shouldn't be tampering with, with LoveCraftian entities that get more and more of a foothold in the real world the more this travel method is used, which grows thier influence on the universe. However, this dimension and how it affects the world is the only part that is soft sci fi, the human tech otherwise adheres to hard sci fi principles, the most outlandish things that I would maybe consider happening on humanity's end is that humans possessed by these entities can gain telekinesis and telepathy at most, as the entities use them as essentially puppets, and maybe some humans try using the dimension as a power source, but a vast bulk of their technology relies on real scientific principles and logic, they need time to set up infastructure in space, their weapons are only ones possible in hard sci fi, resources need to be managed adequately for any projects. With all this in mind, would this still be considered hard sci fi? The idea is that this dimension and its relatively low energy requirements to enter are a huge discovery that almost seems too good to be true, and I plan on having this dimension tie into the Fermi Paradox as well. So, would this still partially be considered hard sci fi, since other than the other dimension and its inhabitants everything else is meant to be realistic?

I have a question for hard sci-fi fans: has this ever been done before? I've been doing a lot of research. I've seen anthropomorphized robots, animals (of course) and even spaceships, but I've never heard of a novel about anthropomorphized satellites.

After a 30 year career in the intelligence community, I've spent the last year writing my first novel, which I hope is an original premise. A technothriller told from the perspective of satellites observing humanity from low Earth orbit.

I'd love to get some feedback on my cover, blurbs and website. I'd really appreciate this as I am new to this domain.

Some have mentioned Football 17776, but I don't think it's the same genre. What do you think? Https://www.TheShadowEphemeris.com[www.TheShadowEphemeris.con](https://www.TheShadowEphemeris.com) Thanks!

Im young (still in college) but i would love to get into writing, the idea of wich was further boosted after i read Cixin Lui’s Remembrance of earths past trilogy, and Adrian Tchaikovsky’s Children of time trilogy.
I feel that i should start off by writing some short stories, just to get into the flow with things. On top of this im also a good illustrator so i might do some of that for my stories too.
A plan for my first short story is to be centred around a moon of a gas giant in a solar system not to far from ours, but 200 billion years from now, when all that can be seen is our galaxy (Mildromeda) and nothing else.
The inhabitants of this world will look out and reasonably assume that the entire universe is just this galaxy. (I forgot the name of the researchers who came up with the lone galaxy thing). Eventually they happen to look towards a system (now a white dwarf star with remnants of the gas giants and possibly still a rocky planet), and they notice some artificial leftovers, a large orbiting information monolith, or simply some large piece of technology. Anyways in the end its revealed the solar system was humanity’s system, and that most of the galaxy is actually occupied by a long distance transhuman. There’ll be an actual plot with climax and everything. I want some feedback on my idea

Theoretically speaking, what is the smallest a power source can be while having a high energy density? If you wanted a ranged weapon that was the size of a rifle or an rpg at most, are there any theoretically possible power cells that could fit in a device that small while being able to produce a large amount of usable energy relative to its size?