For getting the feel of the milky way, I think there's nothing that is better able to simulate it than a video game, ala Elite Dangerous. I loved to navigate its galaxy map. The size of the Milky Way, the numbers of stars and distances between them are of scale in there if I recall correctly.
One particular "feel" that people often get wrong: on a scale of up to around 1000 light years in each dimension (on the order of a million stars, or a hundred thousand sun-like stars - I haven't done the integrals over the density), the placement of star systems is largely homogenous. Most galaxy-scale structure (such as the spiral arms, or core vs rim) only starts becoming significant when you get bigger than that.
Now there are 2 caveats to this - first, there is a measurable density difference as you get closer to the galactic plane. And second, globular clusters do do their own thing.
What this means for fiction is that you must commit to either:
* The overwhelming majority of systems must be irrelevant; relevant systems are hundreds of lightyears apart (it is trivial to disappear into uncharted systems assuming you can maintain your spacecraft), and galactic structure does matter. Or,
* If even a modest percentage of systems are to be relevant, then you can't care about galaxy-scale structure at all. And you need to have something stopping people from gratuitously flying out of bounds (this might be as simple as "no compatible languages and no compatible fuel pumps").
That's interesting, so fiction would be more realistic if they always have distances of hundreds of lightyears apart?
But that means that galaxy-scale structure actually does matter, right? A hundred thousand sun-like stars isn't all that much, I'm guessing only a small percentage-points of those would have a planet in the correct orbit for terraforming, and you'd need to go outside your proposed 1000 LY volume?
I recently saw a video that really put in to perspective for me just how impossibly large the Universe is. The idea is finding your way back to Earth from 1 billion light-years away. Not just thr Milky Way, but also how much more there is outside of it.
Unsurprisingly with ~400 billion star systems, less than 0.01% have been explored.
If there were galactic empires like you see in science fiction, the amount of administration required to deal with that many systems would be mind boggling, the volumes of data would be staggering.
This point is why I find series like Dune or even aspects of Foundation implausible .
At the scale of interstellar empires machines are have to do most of the administration. You cannot centralize so much bureaucracy without computers involved .
I understand the need for science fiction to focus on the human drama, but trying to have empires and be anti-machines is unrealistic.
I am not familiar, so I don't know, but do they assume something like 31,536,000x speed of light to make the galaxy even remotely navigable, e.g., the ability to navigate from Earth to Alpha Centauri within 4.34 seconds?
When I try to explain to someone just how big and massive our universe is I usually fall back to the Voyager 1 satellite which was launched almost 50 years ago. I like to tell people that it is traveling at an amazing 17km per second! Even at such an amazing speed it has still only just traveled approx 1 light day. At such a speed it will travel about 1 light year every 18,000 years.
Then I like to say the nearest next start is roughly 4 light years away. So even at 17km per second, or about 10.5 miles per second, it will still take approx 72,000 years for it to reach the nearest star.
That star is 4 light years away and our galaxy is about 100,000 light years across. The next galaxy is about 2.5 million light years away!!! So at the incredible speeds of one of our fastest man made objects it would take something like 45 billion years to just get to the next galaxy!
Seeing how the known universe is estimated at over 46 billion light years in size and looking back on the other numbers I wrote it quickly becomes apparent that to travel across the galaxies one would need to be able to reach unbelievably unimaginable speeds. Even the speed of light as you mention would not be even close to fast enough to get anywhere significant.
On a side tangent I was always a trekie back in the day. I know their warp drive was faster then light but now I almost want to go back and look at the math of how fast they must have been going to be going the distances they were going.
There's FTL travel of course, but you can navigate at 'normal' speeds as well. The normal speeds really show how there's no way to get to any other object even at full throttle (without FTL). It's just for asteroid belts, space stations and so on. the way they did it gives a really nice intuition of the enormous size of space. It's a fantastic game!
Everything in "Elite: Dangerous" is about getting scales right, contrary to most of its concurrent games. That was amazing from the beginning for planets scale, to systems scale, until you realize it is also right at galaxy scale.
To me, it's a pitty that Braben finally dropped realistic newtonian physics (limited velocity is simply a plague in 99% of space games, period... and sure, I don't talk about FTL travel) in such realistic scales. Complete paradox.
I recently contemplated about a thing: on a galaxy scale, the speed of gravity (or gravity change) should have a somewhat noticeable effect. There's a slight pull towards a star on the other side which is not there anymore for 50000 years! Of course there's some other star in that place, but I wonder how minuscule that effect is. Would it speed up or slow down rotation of outer regions of galaxy?
Gravity works the same as light - if you see it somewhere, it pulls you in that direction. The fact that it’s somewhere else now is irrelevant, because the now is tightly coupled to the where thanks to relativity.
I found a neat little artist page where they have the local star map, the milky way, the local super cluster and a bunch of other neat laser crystal stuff: https://www.bathsheba.com/crystal/#astro
I'd get one, or for that shipping cost make a better one and send them the data, but current shipping in and out of the US is ... interesting.
A quick google on openscad shows how someone build a model of the solar system: https://www.chrisfinke.com/2016/03/08/animating-the-solar-sy... if anyone else wants to have a go this would be a good place to start generating a model to send to the artist.
Unfortunately the local star map hasn't been updated in quite some time. (There's an argument to be had if the sub-brown dwarfs are proper stars but Luhman 16 certainly is https://en.wikipedia.org/wiki/Luhman_16 )
I emailed them about eight years ago to ask if an updated version might include recent WISE discoveries, and the reply I got indicated little interest in doing so.
When the Fermi Paradox was first posited, scientists and engineers seemed to believe that interstellar travel was soon to be technologically achievable, a few decades, maybe centuries for the less optimistic. Progress around space propulsion has kind of stalled since then and we should maybe question the possibility of interstellar travel as this would give an easy but unpleasant answer to the famous paradox.
Right- “where are all the aliens?” is answered by either “they don’t exist” or “they do but physics of the universe prevent them from moving between solar systems.”
Or: we're the first (or among the first). The history that led to space travel (modern human technology) has passed through an insane amount of unlikely scenarios.
A few of these:
* Astronomical: the sun is unusually calm for a star. Jupiter blocks comets. Saturn blocked Jupiter from destroying the Earth.
* Earth is 4.5 billion years old. In the next 0.5-1 billion years Earth will become unhabitable because the sun's luminosity is increasing. We're in the twilight years of the (life-supporting) planet.
* Above point + think about all the species that came before us. Life appeared 3.5-3.8 billion years ago. It took that long to get to humans.
* Dinosaurs got wiped out. Would humans have even evolved if a cosmic event hadn't cleared the board?
* We think that human ancestors dropped down to about 1000-100,000 individuals about 900k years ago.
There's also the question of how many sun-like stars in terms of metallicity there are that preceded the sun. Our sun inherited a lot of heavier elements from a previous generation of star(s).
Add all of these together and we might be early to the party.
Or by "none exist right now nearby". If there are technological aliens 3 bly away and 3 bya, we won't likely discover their signals. If there are technological aliens 10 ly and 10 ya then we're extremely likely to pick up their signals (if they emit any), but they're not likely to come here -- not anymore than we are to go there. The Fermi paradox is most easily understood as "the probability of two concurrent technological species in different but nearby star systems is vanishingly small".
For all we know there have been thousands of technological species in our galaxy, but never two at roughly the same time and roughly close together, and never will be.
This feels very defeatist to me. Technology continues to advance, exponentially. And there are hypothetical ultra fast space travel technologies that we haven’t yet been able to fabricate but could theoretically in the future. e.g. Alcubierre warp drive.
I dislike either/or answers in such open-ended scenarios. It points to our lack of humility in the vast unknown.
eg: maybe they exist(ed) but once a civilization gets advanced enough to build FTL-like travel, they invent AI and use it for warfare and then soon cease to exist. This would mean there are potentially many civilizations (and AI?) that are budding and could travel through the universe.
eg: We aren't in an interesting enough place to bother visiting.
eg: they exist and know about us but have "prime directive" (Ala: Star Trek) laws that state they can't make contact until we reach a stable enough civilization to invent warp drive (or some other advancement.)
eg: There is some exotic reason that our pocket of the Milky Way is un-navigable.
We do know how to build interstellar-capable propulsion. It'd still be a generational ship but we know how we could do it within the span of a few human lifetimes. Building them is a matter of organizing the resources to actually make it happen, and we haven't had the collective will for anything like that yet.
We do not know how to build one. We could build something of that size maybe, but we couldn't make it last long enough to get anywhere. Some astroroid will randomly hit it in the worst spot and break it.
It'd have to be pretty darned big, to sustain a population large enough to remain viable for a couple of centuries. You'd then have to figure out how to get enough delta-v on it to escape the solar system, but then you'd also need a way to get yet more delta-v at the other end, to slow enough to get captured in a useful orbit, or else fly right on out the other side. Assuming there's a planet you're aiming for, you'd want to establish an orbit of that. So this has to be a small asteroid scale ship, with propulsion that works, after centuries of micro meteorites and radiation, and possibly substandard maintenance.
I’d be pretty pissed at my parents if I was born on a Starship and condemned to die on it too. Imagine living your entire life in a Winnebago and you can’t even go outside.
Yep. From a light emitter's perpective, it is directly embedded in all of the places surrounding it that its light would eventually reach. Your eyeball, a distant dust spec 4 million light years away, and a black hole are all directly adjacent and it tosses photons onto the shell around itself, painting it with light. The photons arrive at the same instant that they are emitted, if you don't count the millions or billions of years in between. And the photons don't.
That thought randomly hits me all the time when I'm taking out the trash or whatever and just happen to look up. That and the fact that the Bootes Void and Phoenix A* exist out there.
Nit of a nit; the energy might take that long, but the photons that reach us on Earth are not directly created by the nuclear fusion reactions in the sun's core. Fusion creates high-velocity nucliei and other particles, but not visible light. The resulting heat creates photons which are rapidly destroyed by absorption. Only photon emission from the outer most layers of the sun reach Earth.
This is interesting to me because somehow I’ve had in my head that if we develop the ability in the next couple centuries to send probes interstellar it would be a longer list of possible targets. What this makes me realize is the list of places we visit even in the next thousands of years - even with incredible leaps in propulsion - is very finite. Space may be really really big but the part physically accessible even in long timescales is limited.
During COVID, I had a lot of spare time and an aversion to reading the news or indeed anything on social media. So, I got interested in trying to wrap my head around the scale of the universe. I built an app called VOS - https://vos.ajmoon.com - which would plot things at scale on a map, allowing me to plan a walk (e.g. from the sun to Pluto) with various celestial objects at that scale. Then I made videos of some of those walk plans, explaining what you'd encounter. It was a lot of fun!
If you can travel near the speed of light, the trip back to a future era of Earth would almost always be more exciting than stepping onto a distant barren planet.
Edit: "back to a future era" hehe-- i.e., the trip away and then back to Earth at near-light speeds will always put you way further into the future than you would have been just staying put on Earth. At the current rate of technological change, you're guaranteed some exciting new changes that will almost always be more exciting and surprising than whatever planet you visited.
Readit News
Now there are 2 caveats to this - first, there is a measurable density difference as you get closer to the galactic plane. And second, globular clusters do do their own thing.
What this means for fiction is that you must commit to either:
* The overwhelming majority of systems must be irrelevant; relevant systems are hundreds of lightyears apart (it is trivial to disappear into uncharted systems assuming you can maintain your spacecraft), and galactic structure does matter. Or,
* If even a modest percentage of systems are to be relevant, then you can't care about galaxy-scale structure at all. And you need to have something stopping people from gratuitously flying out of bounds (this might be as simple as "no compatible languages and no compatible fuel pumps").
But that means that galaxy-scale structure actually does matter, right? A hundred thousand sun-like stars isn't all that much, I'm guessing only a small percentage-points of those would have a planet in the correct orbit for terraforming, and you'd need to go outside your proposed 1000 LY volume?
https://youtu.be/uUuM8NdmaAU?si=7It672waw734e9nK
If there were galactic empires like you see in science fiction, the amount of administration required to deal with that many systems would be mind boggling, the volumes of data would be staggering.
At the scale of interstellar empires machines are have to do most of the administration. You cannot centralize so much bureaucracy without computers involved .
I understand the need for science fiction to focus on the human drama, but trying to have empires and be anti-machines is unrealistic.
Then I like to say the nearest next start is roughly 4 light years away. So even at 17km per second, or about 10.5 miles per second, it will still take approx 72,000 years for it to reach the nearest star.
That star is 4 light years away and our galaxy is about 100,000 light years across. The next galaxy is about 2.5 million light years away!!! So at the incredible speeds of one of our fastest man made objects it would take something like 45 billion years to just get to the next galaxy!
Seeing how the known universe is estimated at over 46 billion light years in size and looking back on the other numbers I wrote it quickly becomes apparent that to travel across the galaxies one would need to be able to reach unbelievably unimaginable speeds. Even the speed of light as you mention would not be even close to fast enough to get anywhere significant.
On a side tangent I was always a trekie back in the day. I know their warp drive was faster then light but now I almost want to go back and look at the math of how fast they must have been going to be going the distances they were going.
To me, it's a pitty that Braben finally dropped realistic newtonian physics (limited velocity is simply a plague in 99% of space games, period... and sure, I don't talk about FTL travel) in such realistic scales. Complete paradox.
I'd get one, or for that shipping cost make a better one and send them the data, but current shipping in and out of the US is ... interesting.
A quick google on openscad shows how someone build a model of the solar system: https://www.chrisfinke.com/2016/03/08/animating-the-solar-sy... if anyone else wants to have a go this would be a good place to start generating a model to send to the artist.
I emailed them about eight years ago to ask if an updated version might include recent WISE discoveries, and the reply I got indicated little interest in doing so.
A few of these:
* Astronomical: the sun is unusually calm for a star. Jupiter blocks comets. Saturn blocked Jupiter from destroying the Earth.
* Earth is 4.5 billion years old. In the next 0.5-1 billion years Earth will become unhabitable because the sun's luminosity is increasing. We're in the twilight years of the (life-supporting) planet.
* Above point + think about all the species that came before us. Life appeared 3.5-3.8 billion years ago. It took that long to get to humans.
* Dinosaurs got wiped out. Would humans have even evolved if a cosmic event hadn't cleared the board?
* We think that human ancestors dropped down to about 1000-100,000 individuals about 900k years ago.
There's also the question of how many sun-like stars in terms of metallicity there are that preceded the sun. Our sun inherited a lot of heavier elements from a previous generation of star(s).
Add all of these together and we might be early to the party.
For all we know there have been thousands of technological species in our galaxy, but never two at roughly the same time and roughly close together, and never will be.
eg: maybe they exist(ed) but once a civilization gets advanced enough to build FTL-like travel, they invent AI and use it for warfare and then soon cease to exist. This would mean there are potentially many civilizations (and AI?) that are budding and could travel through the universe.
eg: We aren't in an interesting enough place to bother visiting.
eg: they exist and know about us but have "prime directive" (Ala: Star Trek) laws that state they can't make contact until we reach a stable enough civilization to invent warp drive (or some other advancement.)
eg: There is some exotic reason that our pocket of the Milky Way is un-navigable.
Without electricity, how well would we understand it? Just that some mysterious rocks that stick?
Wonder if one day in the distant future we’ll discover a new force we never imagined.
For example, when we look at the sun, that’s 8-minutes-old light. When we look at Polaris (the North Star), that light is 447 years old.
When we look at Andromeda?
Yeah, that light is 2.5 million years old.
It's not an easy task from the prospective of a photon, which can be easyly proven with just two little slits.
During COVID, I had a lot of spare time and an aversion to reading the news or indeed anything on social media. So, I got interested in trying to wrap my head around the scale of the universe. I built an app called VOS - https://vos.ajmoon.com - which would plot things at scale on a map, allowing me to plan a walk (e.g. from the sun to Pluto) with various celestial objects at that scale. Then I made videos of some of those walk plans, explaining what you'd encounter. It was a lot of fun!
Edit: "back to a future era" hehe-- i.e., the trip away and then back to Earth at near-light speeds will always put you way further into the future than you would have been just staying put on Earth. At the current rate of technological change, you're guaranteed some exciting new changes that will almost always be more exciting and surprising than whatever planet you visited.