People lament the light speed barrier, because it seems to preclude vast space empires of Sci-fi. But there are countless bodies at vast distances just within a few light years. If we develop fusion power, just the neighborhood of the Sun and the Centauri systems would constitute tens of thousands of colonization suitable dwarf planet sized bodies or larger. If we build artificial habitats, the population of all of those systems could easily number in the trillions. That's a pretty vast setting.
But it is worth asking why people want to believe that a narrative can be extended to space? Humans structure their experience using narratives, and this works okay on Earth. Though even on Earth, there are many known problems with the way humans use narratives:
1.) police will tell you that eye witnesses are highly inaccurate
2.) psychologists can tell you all about the way people hurt themselves with inaccurate narratives about themselves
3.) human rights activists work constantly against narratives that take a racial category as a first class character, with real and knowable attributes
And those problems arise on Earth. At least since Einstein's Theory Of Relativity we've known that normal human narrative will not extend to space. And yet people want to this to be true. There is a kind of nostalgia that infects most writing about space, a belief that our exploration of space can be like the discovery of the frontier in centuries past. Even intelligent people sometimes talk this way, even though they know it is an inaccurate way to think about the universe.
I suppose this is sort of in the category of "Why do 99% of sci-fi movies act as if there is a gravity on spaceships, or assume a technology that can easily assume that a 1 G warp of the space time continuum does not itself warp the ship into a ball?"
Basically, people don't want their sci-fi stories to be too accurate. And I guess that's fine. Maybe it's all just entertainment. But then we shouldn't take that entertainment and act like any of it can ever be real.
At least since Einstein's Theory Of Relativity we've known that normal human narrative will not extend to space.
Meh. Human narratives have encompassed characters who live for hundreds of billions of years and who experience time warped in any number of ways. There are even successful mainstream movies that deal with such issues. Multiple ones going back decades.
Basically, people don't want their sci-fi stories to be too accurate. And I guess that's fine. Maybe it's all just entertainment.
You could totally re-tell the entire Star Wars and Star Trek canon in such a setting. It's not that people don't want it. Most people don't know enough to know they would want it. Heck, half of everyone seems to think "there's no gravity in space."
(EDIT: By "such a setting," I mean in just several cubic light years around Sol and Alpha Centauri.)
"You could totally re-tell the entire Star Wars and Star Trek"
Both of those are fiction, so they are not relevant. I think we all get why people like fiction -- it's entertaining and some of the better stuff is educational. But why do intelligent people want to believe that any such coherent stories can actually be told in real life? We all know it's impossible. Even basic questions such as "How old are you" become unanswerable. A person gets in a ship and travels at 1 G to another star, then turns around and comes back to Earth, they've aged 20 years, meanwhile on Earth 200 years have passed and all their friends are dead. Which timeline is real? How would any sci-fi tropes play out, in real life, in a universe of such inconsistencies?
Consider the issue of law enforcement. How could a central authority enforce its power, if people knew they could commit a crime, live a long life, and die before any forces from the central authority arrived? The notion of a political entity existing at more than solar system scales is ridiculous. Intelligent people know this, yet many of them still seem to want to believe that such a thing is a possible. Why is that?
But why do intelligent people want to believe that any such coherent stories can actually be told in real life? We all know it's impossible. Even basic questions such as "How old are you" become unanswerable.
Really intelligent informed people know the relative scales involved. So if all of Star Wars were re-imagined to occur using reasonable tech within the several cubic light years around Alpha Centauri, no speeds where severe relativistic time dilation effects are necessary for normal transportation. "How old are you" is readily answerable +/- a month for just about everyone, even most spacefarers. Heck, even the prequel trilogy makes more sense. (As Plinkett puts it, why are people on the planet of Naboo dying because they lack, "Space Supplies?" It would make a whole lot more sense if Naboo were an icy ball in the Oort cloud.)
A person gets in a ship and travels at 1 G to another star, then turns around and comes back to Earth, they've aged 20 years, meanwhile on Earth 200 years have passed and all their friends are dead. Which timeline is real? How would any sci-fi tropes play out, in real life, in a universe of such inconsistencies?
Another thing: I'm not an expert myself, but I can already tell that you don't even understand the big abstractions of relativity that well. The "Twin Paradox" is not actually a paradox. There is a global set of spacetime intervals which is consistent among all observers. It's only each observer's view of the spacetime interval which disagrees between observers. I'm probably saying that wrong, but the gist of that should be right.
The "Spacetime Globe" by Minute Physics is the most helpful.
It's like you're a 2D flatlander declaring that a cube would be seen as a square by one person and a hexagon by another, so the 3D universe must be an inconsistent database. Uh, no. The universe is totally consistent. You, poor finite human, just have a slim, parochial view of it.
"People lament the light speed barrier, because it seems to preclude vast space empires of Sci-fi."
Assume you are the Emperor of a vast interstellar empire. You order your best general to go and attack a star system 10 light years away. Your opponent possibly does the same. 20 years after you give the order, you are told that your general lost the battle (or won the battle). How would you verify that? It's not just that you have to wait another 20 years to verify it, it's that events will pile up in excess of what you can verify. The best way to understand the outcome of this battle is to read what Kyle Kingsbury has written about distributed databases:
Because, for all practical purposes, the Universe is a distributed database with a serious network partition. It is not Eventually Consistent, but rather, it is Infinitely Inconsistent. The writes exceed the reads, and will continue to do so infinitely into the future.
How do you build an interstellar empire around that reality?
As an experiment, it might be fun to create a game that is deliberately inconsistent. That would appeal to a very small niche, because most people crave a consistent narrative experience. But a game designed around a database that is deliberately inconsistent would help people think correctly about the difficulty of building empires in space, or engaging in any other common sci-fi tropes.
If there's anything the universe is, it's Eventually Consistent. Nobody has ever found a case where it isn't. Relativity was predicted to exist because "eventual consistency" was assumed axiomatic in our universe. Essentially, eventual consistency is exactly why the universal speed limit exists.
> but rather, it is Infinitely Inconsistent
We will fall behind in knowledge of events, but causal knowledge of an event in our universe, if it exists, is always consistent.
Knowledge of events in our universe is like an immutable, append-only database (think git), not data that gets updated (like a key/value database).
> If there's anything the universe is, it's Eventually Consistent.
Please disregard this inconsistency guff! The Universe isn't Eventually Consistent. It's simply consistent. What's really going on, is that some programmers don't understand relativity. Relativity doesn't actually say that everyone gets their own reality. There is a consistent consensual reality. Spacetime intervals are consistent between all observers. The time ordering of events changes depending on the observer's POV and relative motion, but there is an underlying consistent reality that's the same for everybody.
The "Spacetime Globe" by Minute Physics is the most helpful thing I've seen, flat out, for understanding relativity.
> Knowledge of events in our universe is like an immutable, append-only database
This is correct. Relativity just says that different users get different results, depending on how they query. The underlying database is the same for everybody. (Some parts of it are forbidden access, of course.)
Programmers have been causing physicists to facepalm since at least the USENET days. I should know. I was one of them!
> Please disregard this inconsistency guff! The Universe isn't Eventually Consistent. It's simply consistent.
We agree except for what we mean by "eventually" which is just semantics. What I mean by "eventually" is that eventually all the information arrives for my (or anyone's) model of the universe to match reality, analogous to eventually consistent distributed databases. Like an eventually consistent database however we can never catch up completely, since new events are happening in the universe all the time. It takes time for this information to "replicate", but there is no inconsistency. I was following lkrubner's analogy.
Assume you are the Emperor of a vast interstellar empire.
Your next few sentences disprove the viability of the sentence above. If you want a vast interstellar space empire, then control a whole bunch of settlements that orbit in the space between Sol and Alpha Centauri. It's certainly vast on human scales. It's also technically interstellar.
As an experiment, it might be fun to create a game that is deliberately inconsistent.
A friend of mine created such a space combat themed game, including paradoxes and rules for resolving them. I 3D printed pieces for it. It was indeed fun, so the answer to your conjecture is yes.
Isn't that a similar problem to what seafaring empires had ~500 years ago and earlier? Perhaps the time delay wasn't as long, but news could take months or years to get back to "HQ" about what was happening in far flung lands.
Give them freedom to take action and eventually independence to act completely on their own.
No, because on Earth one can reconcile time. If Vikings go to Newfoundland, fight a battle, and return to Norway 10 years after they left, both the people in Norway, and also the warriors who went to Newfoundland, will agree that 10 years passed. You don't end up with one group feeling that 1 year passed and another group feeling 10 years passed, and perhaps a different group that feels 100 years have passed.
It doesn't matter whether 10 or 100 years have passed, the only thing that matters is causal order. After all, the King only needs to assign punishments and rewards, and those are based on what happened and why. "What happened and why" is the same in every reference frame.
Even things like 10-year jail sentences will still work, because you clearly are asking for 10 years from the perspective of the convict.
The tools with which people construct narratives change. Exploration of space should bring with it new concepts such as for example might arise when an interstellar colony ship culture meets the culture of the earlier arrivals. Old concepts such as leaving for the New World will be relevant again.
These are opportunities for intelligent life to create new meanings to its existence. Sci-Fi was not born out of a vacuum.
Why was this downvoted? It certainly is appropriate to ask why smart people want to believe that the kind of narratives we know here on Earth can be extended to space. Intelligent people know this isn't possible, so it worth asking why the desire to have these stories is so strong.
A narrative is a sequence of events that happen in a definite order. Humans can not have that kind of experience as they spread to space -- everyone's narrative will be relative to themselves, but they won't reconcile with each others narratives. This is well know. The question is why even smart people prefer fiction that ignores this fact. It's worth asking that question.
I didn't downvote you, but perhaps it's because the idea either lacks a good understanding of the scales involved, or has been effectively disproved by the Sci-fi corpus decades ago. (Just one example of many: Haldeman's Forever War.)
Some users break HN's voting system. Often they either don't understand or disagree with what you are saying, and that in their value system means they should downvote.
My guess is that if we increase our lifespan by a lot then long travel won't be that bad. Let's say your life expectancy is 1000 years your perspective totally changes and a 200 year trip isn't that bad.
It's not the time, it's the energy. To get to the nearest star (4LY away) in 200 years, you'd need to accelerate to 2% of light speed (6000km/s) and have the means to slow down when you arrive.
And that's just the energy to move you- how do you stay fed, etc, for 200 years far from any star?
With fusion power, the ability to turn water into vast energy, you are correct in that we would have no need of stars. We could grow our food and build our cities out of asteroids. It would be rather dark and cold, but we would have no absolute need to live on the surface of a planet. Once out there we might find so many places to live that we loose the urge to voyage to new stars.
I think one answer to the Fermi paradox might be this: By the time our descendants get to the other edge of our galaxy, they will have changed into countless other forms so different, we of today might not be able to easily perceive them at all.
I haven't been keeping up on this topic. It's very exciting. If I'm understanding what I've read, this is the furthest of the "dwarf planets" which lie well beyond Pluto. There is a hypothesis that another planet (Planet 9) larger than the earth is out there as well. Planet 9 is what they believe explains some orbital peculiarities shared by these dwarf planets? Is the Planet 9 thought to be even further out than "Farout?"
It makes me wonder if there's a distance so great in the observable universe that light from an object would spread out so much that it couldn't be recognized as an object.
I'd imagine there are distant stars ejected from galaxies that would render only as single pixel. It seems possible given enough distance that an entire galaxy could render as a single pixel as well, but I wonder if that distance is greater than the observable universe.
There certainly are telescopes that capture images of objects so faint we have to wait long periods of time just to catch a few photons. This is enough to do some interesting astronomy, perhaps surprisingly.
If you have a big enough telescope and point it at something long enough, you can almost always resolve it better than just one pixel.
There is one hard physical limit though. Due to the expansion of space, there are in fact objects so far away that their light will never reach Earth---one might say that space is expanding them away from us at faster than the speed of light.
And because this expansion is actually getting faster all objects are actually accelerating away from us. That means all the time, there are objects that speed up from sub-lightspeed to super-lightspeed as they move away from us. Once they cross that lightspeed barrier, their light can never reach us again.
So it's concievable that we might just happen to capture the last photon of some object that will ever reach us. In that sense, then, some objects are indeed so far away that for a brief period of time, any image of them can only hope to be a single pixel, no matter how good your resolution or magnification.
What exactly do you mean by "render only as a single pixel"? With a low enough resolution sensor, the sun would render as a single pixel when observed from earth.
A guy who worked at the undergraduate computer lab when I was in college in the 90's was bemused by all of the print samples and signs by the laser printers, so he made his own:
The caption read, "This is Chris rendered in one color at 1 DPI on the Dinotronic," underneath a 7x7 monochrome portrait of himself.
I think part of what you are asking is, "If we can't resolve the disk of a object, how do we know if it is a galaxy or a star?" The answer is that we can tell a lot about a point source based on its spectrum. For example, quasars were first noticed solely by their spectra.
The other thing to consider with distant galaxies is that they are moving away from us very quickly. The further away they are, the faster they are receding, and the more red-shifted their spectrum becomes. This is why JWST has different spectral response from Hubble.
You're ignoring Alpha Centauri A and B, which are much larger. Also, even without the Alpha Centauri system, very distant orbits (more than 2-3 ly or so) would be destabilized by the galactic tide, i.e. the gravitational gradient of the Milky Way galaxy.
Some estimates for the outer boundary of the Oort Cloud put it at 200,000AU = 3.16ly (more conservative estimates seem to be 1ly or less). Even the inner boundary is thought to be at least double the distance of the object just discovered, so current astonomical hypotheses align with your idea that there's a lot more out there.
Alpha Centauri A has a mass of 1.1x the sun, and is about 4.37ly away, which would mean our sun's gravity well runs out at
(1/2.1)*4.37 = 2.08ly - i.e. any object in orbit 2.08 ly away would (even if affected by nothing else), fall into Alpha Centauri A's gravity well before completing a full orbit and therefore couldn't possibly remain in orbit around our sun.
If that's true (and I have no idea whether any of it is true), then I think 2.08ly must be an upper bound on the outer boundary of the Oort cloud.
EDIT: Ah, I'm thinking 2-dimensionally. Of course, something could be in a much larger orbit in a plane that doesn't go near Alpha Centauri.
While it's currently closer, "The Goblin" has an aphelion of 1955 AU: https://en.wikipedia.org/wiki/2015_TG387. That's still only .03 ly, but we already know about objects whose orbits go much further.
>> The object from the article is about 0.0019ly away, so there could be quite a lot of new most-distant solar system objects still to be discovered!
And yet, Voyager 1 and 2 have now "left the solar system" and entered interstellar space. It looks to me like the definition of what's part of the solar system is a bit squishy.
So this object is a bit more than 11 billion miles from the sun?
And Alpha Centauri is 4.2 light years away, which is 24,635,923,200,000 miles?
So this object is roughly 0.046% of the way to the next star?
Assuming that the Alpha Centauri system reaches out to us as much as our system reaches out to Alpha Centauri, I am surprised that the two systems reach out to each other as much as they do.
Almost 10% of the distance between the stars consists of the systems that surround the stars?
