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 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?
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!
This was already present in Frontier: Elite II released in 1993. You could travel at sub-light speeds as far as you wanted, visiting gas giants within the same star system and scooping fuel. But to get anywhere else, hyperspace was the only practical option.
The crazy part is that this 3D game was programmed in 68k assembly, ran smoothly on Amiga and Atari ST home computers, and fit on a single 1.44MB floppy. The massive universe with realistic solar systems was almost entirely procedural.
Agree. I've mentioned to a few friends how that feeling of emptiness and scale is quite awe inspiring and was a first for me. Theory can't replicate how small and isolated you physically feel when you are between systems. At least not for me.
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.
> I almost want to go back and look at the math of how fast they must have been going
While there's a rough polynomial (v =~ c * w^3, I think) for post-TOS Star Trek warp factors, the only consistent rule: a starship travels at a velocity that helps tell a good story.
It's fun to try mapping Star Trek stories, anyway; it helps you ponder how much time they must have spent in transit. They have to find things to occupy their time.
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.
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.
I believe this argument is fallacious. There could be infinite other ways a species could have evolved to acquire space technology. A smart dinosaur that evolved to use arms and tail could perhaps have built an industrial civilization. They would’ve been now 100 million years old! Imagine the progress. Them being wiped out probably just delayed civilization by millions of years.
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 know enough physics to rule out any ftl travel. Assuming that is correct which seems very likely they can't get here, even radio signals is question able - even if radio signals can get here either they have already passed and their civialization (sun) is dead or ours will be dead by the time they arrive.
Cherenkov radiation is a proof, that FTL is possible. We just cannot accelerate enough. However, «burps» from blackholes are proof that blackholes can do that. To achieve singularity, outer layer of blackhole core must spin at a FTL speed anyway.
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 think our recent forays to microscopic and sub-microscopic things like computers have really distorted our views. Just look at something like EV. Give say 10x efficiency(very high) increase and we are actually still faraway from even interplanetary travel.
Physical world is big and getting from one point to other takes lot of energy and involves lot of mass.
Why should we believe it will continue to advance exponentially? And even if it does, we many find none of the hypotheticals pans out - perhaps we advance exponentially and there is nothing feasible to reach even 0.01c
The fabric of spacetime itself sets the ultimate speed limit. Nothing can locally move through it faster than light. For example, gravitational waves ripple across the universe at light speed.
Anything that exists within spacetime is bound by this rule. The only odd exception people point to is quantum entanglement, but while the correlations appear instantaneous, they can’t be used to send information faster than light. Sending matter is distant second.
So, if we ever hope to travel faster than light, we wouldn’t do it by "outrunning" gravity. Instead, we’d need to find a way to manipulate spacetime itself, like bending, warping, or reshaping it ... since that, in the first place itself, is what is defining the limits of motion.
More like technology evolves in spurts. Huge gains within a specific area for 2-3 decades and then only small incremental advancements for the next 2-3 decades.
If the Alcubierre drive were possible, some civilization would have already discovered it, and we would see evidence of its use. This is certain to be the case with any kind of FTL travel, if such a thing is even possible.
But when we observe the universe we see nothing. Therefore either no advanced life exists in the universe besides ourselves, which seems unlikely, or none have spread to space in any significant degree and FTL is either impossible or so difficult no one bothers. There doesn't seem to be a secret third thing that both satisfies our observations and obeys known physics.
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.
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.
... which begs the question of who would really arrive at the destination. Our own civilization starts to rebel at things that were heralded by the previous generation because the current generation doesn't remember the problems that were solved. In two generations, the humans that remain might not leave the ship at all despite having a whole planet (or multiple) to inhabit.
I follow what you're saying, but many folks on this planet have far less opportunities than such a trip might provide. Guaranteed food, housing, access to cutting edge healthcare, a likely united community. I'm assuming these ships would be fairly big. It would definitely be different but-- would it be as bad as we think?
Unfortunately, I suspect that any starship that could bring with it all of those services would also bring with it the economic and political strife of Earth. The are lots of examples of democratic states turning into oligarchies or worse in recent history so that can't work in it's current form at least.
The closest analogue in the real world to the ideal that you describe is, I think, Cuba. It does guarantee food and housing, and it does have a remarkably advanced healthcare system plus what is reportedly a united community. Perhaps most interesting of all, it's politically isolated like a starship would have to be by its nature. Even then, one would have to be either pretty brave or desperate to go along on the journey, as modern Cuba has only been around for half a century and that's at the absolute minimum of an intergalactic starship's practical mission duration.
It would be better than living your entire life in a literal cage on earth. But I think it would be worse than even being a slave on earth. A slave can touch grass and hope to run away. A person born on a generational ship would be effectively enslaved (to perform necessary ship duties). You mention 'cutting edge healthcare', but on earth that requires the substantial and diverse resources of an industrial civilization. The research of millions of people and the infrastructure to breed nuclides and manufacture precise machinery. Does this generational ship have a modern chip fab on it!?
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.
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.
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.
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.
Yep, this is what he saying, but this is not what photon does. Photon must perform different amount of wave cycles to reach 1 meter or 1 trillion metters. These cycles can be counted.
I'm not a physicist, but I believe that's the exact insight that led to special relativity. It goes something like: If your moving at 1,000kmh next to a jet moving at 1,100kmh then the jet is moving at 100kmh relative to you. Eventually people realized those wasn't the case with light. No matter how fast the observer is, light still moves at 299,792,458m/s. Einstein figured out that if the speed of light is fixed despite relative motion, then time must slow down as you move faster. So from the perspective of a photon no time has passed since its departure.
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.
The photons were created a long time ago in the core. It takes thousand of years for it to reach the surface, and THEN it takes 8 minutes to get to us.
Photons are not created on the surface but in the core where the environment has the higher pressure needed for the physical creation of the photon and the photon takes about that long to work its way out.
It should be a goal for Earth to send a probe to one of those stars. As the probe will be unmaned, a mission taking a hundred years or more is not out of question.
There are already plans to reach alpha centauri in about 20 years with unmanned probes (1). There still remain some technical hurdles in terms of the laser design to propel these probes afaik but it seems like this could be solved with more funding.
Too bad we are in the current era of eschewing scientific research in favor of crony politics.
Something like Starshot seems like it could benefit from future developments without holding back a launch today. Something with a sail can always have a laser aimed at it; maybe we launch it today with a tiny laser we fire from orbit, and in 50 years, we accelerate them to a significantly better cruising speed by firing from a laser array on the moon.
One issue with the latter is that tech is likely to advance fast enough that a subsequent probe launched a couple of decades later would overtake the first probe.
I’d still settle for getting the probes out the door because no matter what advancement happens if you can’t get them into space it’s a moot point. I’d simply take something we can reasonably launch into space for research at this point.
Also, I would love to see a lunar base happen in my lifetime
Yeah, I don’t think it will happen that fast. There are a lot of hard problems to solve, and you have to make a case for the expected scientific (or other) benefits to be worth the costs. Look at how long the JWST took from initial planning to launch, that was about twenty years, despite clear and specific objectives.
Unlikely, but possible (if the probe was really big or really chatty in parts of the spectrum we pay attention to). Tiny probes could pass by us without us noticing them I'd think, though if they needed to send transmissions back toward their origin we might pick that up.
As someone who has been fascinated by the universe and galaxies from a young age, I too thought interstellar was the way to go. Nowadays, however, I've started to feel that we've been wrongly conditioned by science fiction to see interstellar exploration as the next logical step for humanity.
Our species is still very immature ethically, socially, and politically. We haven't even learned to accept each other and co-exist happily on Earth. Our distant hominin ancestors crossed entire continents but today we set up physical borders and cultural barriers to prevent even neighborly visits. We certainly won't become the broad-minded united ethical species that Star Trek TOS/TNG portrayed within the next 2-3 centuries.
Gradual spatial expansion, and through that, gradual cognitive and worldview expansion, has been our track record. Whenever things got hairy for someone in our hominin tree at any time, they moved just a little bit more to survive.
So, I feel exploring and settling other solar system bodies should be our next logical step. There are 4 solid planets, 5 dwarf planets, and as per Gemini, ~40 moons, ~3000 asteroid belt objects, and 200000+ Kuiper belt objects, all above 10 km radius. That's a lot of nearby space to explore and more practical than interstellar. Some of them will become the solutions or refuges from our current social and political problems on Earth.
It'll take us 1000s of years more, maybe even 100s of 1000s, to do all this. Including a lot of violence, conflicts and injustice. But eventually, we will learn to develop the cooperative institutions and cognitive/ethical frameworks we currently lack to become a multi-planet species. Interplanetary cooperative institutions and technologies will emerge eventually, just like today we have airplanes, the Internet, UN, WHO, EU - institutions and technologies that, while far from perfect, seemed downright unlikely for 100s of 1000s of years of our hominin history.
some combination of nuclear radiation and/or solar seems like it would fit the bill? 100 years is within the useful range of a large radioisotope generator.
Solar would not work when you're out past Uranus or so, and the Sun is just a bright star with barely a visible disk. There's simply not enough sunlight out there, and you won't get enough light from your destination(s) star until you're similarly close to it.
RTGs lose power rapidly as the isotopes decay, and any sort of communication over those distances requires massive power. The Voyagers are essentially dead due to this issue, and they haven’t been out there nearly that long.
It would likely need a standalone fission reactor that only ‘goes hot’ when it arrives.
I’m not sure that we have the engineering ability to actually do that with any real chance of success after a 100 year deep space flight, or the willingness to wait that long to find out.
There are attempts, but they all suck IMHO :( Someday I'll get around to doing this in Three.js for real, if no one beats me to it. It's shocking that we have a million 3D sites to visualize LEO satellites and plenty to visualize the solar system, but our stellar (much less galactic!) neighborhood is all super outdated stuff only.
I guess the sad reality is that these tools aren't that useful for anything but diagramming the odd interstellar rock.
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 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?
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!
This was already present in Frontier: Elite II released in 1993. You could travel at sub-light speeds as far as you wanted, visiting gas giants within the same star system and scooping fuel. But to get anywhere else, hyperspace was the only practical option.
The crazy part is that this 3D game was programmed in 68k assembly, ran smoothly on Amiga and Atari ST home computers, and fit on a single 1.44MB floppy. The massive universe with realistic solar systems was almost entirely procedural.
Agree. I've mentioned to a few friends how that feeling of emptiness and scale is quite awe inspiring and was a first for me. Theory can't replicate how small and isolated you physically feel when you are between systems. At least not for me.
I suppose they can’t simulate time dilation, which does make it possible to visit other galaxies without FTL.
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.
> I almost want to go back and look at the math of how fast they must have been going
While there's a rough polynomial (v =~ c * w^3, I think) for post-TOS Star Trek warp factors, the only consistent rule: a starship travels at a velocity that helps tell a good story.
It's fun to try mapping Star Trek stories, anyway; it helps you ponder how much time they must have spent in transit. They have to find things to occupy their time.
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.
This great illustration looks like it might have been inspired by a National Geographic poster.
Here's the one they say is from October 1999:
https://www.natgeomaps.com/hm-1999-the-universe
I remember this one was an updated version of a poster they published in the late 1970s or early 80s -- I had a copy on my wall in 1985.
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.
I believe this argument is fallacious. There could be infinite other ways a species could have evolved to acquire space technology. A smart dinosaur that evolved to use arms and tail could perhaps have built an industrial civilization. They would’ve been now 100 million years old! Imagine the progress. Them being wiped out probably just delayed civilization by millions of years.
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 know enough physics to rule out any ftl travel. Assuming that is correct which seems very likely they can't get here, even radio signals is question able - even if radio signals can get here either they have already passed and their civialization (sun) is dead or ours will be dead by the time they arrive.
Cherenkov radiation is a proof, that FTL is possible. We just cannot accelerate enough. However, «burps» from blackholes are proof that blackholes can do that. To achieve singularity, outer layer of blackhole core must spin at a FTL speed anyway.
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 think our recent forays to microscopic and sub-microscopic things like computers have really distorted our views. Just look at something like EV. Give say 10x efficiency(very high) increase and we are actually still faraway from even interplanetary travel.
Physical world is big and getting from one point to other takes lot of energy and involves lot of mass.
> Technology continues to advance, exponentially
Why should we believe it will continue to advance exponentially? And even if it does, we many find none of the hypotheticals pans out - perhaps we advance exponentially and there is nothing feasible to reach even 0.01c
The fabric of spacetime itself sets the ultimate speed limit. Nothing can locally move through it faster than light. For example, gravitational waves ripple across the universe at light speed.
Anything that exists within spacetime is bound by this rule. The only odd exception people point to is quantum entanglement, but while the correlations appear instantaneous, they can’t be used to send information faster than light. Sending matter is distant second.
So, if we ever hope to travel faster than light, we wouldn’t do it by "outrunning" gravity. Instead, we’d need to find a way to manipulate spacetime itself, like bending, warping, or reshaping it ... since that, in the first place itself, is what is defining the limits of motion.
So c is the speed of light in the fabric, right?
More like technology evolves in spurts. Huge gains within a specific area for 2-3 decades and then only small incremental advancements for the next 2-3 decades.
More like technology evolves during global wars.
Fixed that for you. Rev up those stealth fighters!
>Technology continues to advance, exponentially.
Currently focusing on imaginary money crypto schemes and ML chatbots whose data centers use as much power as entire US states, sorry.
If the Alcubierre drive were possible, some civilization would have already discovered it, and we would see evidence of its use. This is certain to be the case with any kind of FTL travel, if such a thing is even possible.
But when we observe the universe we see nothing. Therefore either no advanced life exists in the universe besides ourselves, which seems unlikely, or none have spread to space in any significant degree and FTL is either impossible or so difficult no one bothers. There doesn't seem to be a secret third thing that both satisfies our observations and obeys known physics.
Geminga?
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.
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.
Would you really? when it's the only thing you've ever known you'd probably just accept it as normal.
... which begs the question of who would really arrive at the destination. Our own civilization starts to rebel at things that were heralded by the previous generation because the current generation doesn't remember the problems that were solved. In two generations, the humans that remain might not leave the ship at all despite having a whole planet (or multiple) to inhabit.
Their kids will leave the spaceship though. And some dare devils of their generation.
I follow what you're saying, but many folks on this planet have far less opportunities than such a trip might provide. Guaranteed food, housing, access to cutting edge healthcare, a likely united community. I'm assuming these ships would be fairly big. It would definitely be different but-- would it be as bad as we think?
Unfortunately, I suspect that any starship that could bring with it all of those services would also bring with it the economic and political strife of Earth. The are lots of examples of democratic states turning into oligarchies or worse in recent history so that can't work in it's current form at least.
The closest analogue in the real world to the ideal that you describe is, I think, Cuba. It does guarantee food and housing, and it does have a remarkably advanced healthcare system plus what is reportedly a united community. Perhaps most interesting of all, it's politically isolated like a starship would have to be by its nature. Even then, one would have to be either pretty brave or desperate to go along on the journey, as modern Cuba has only been around for half a century and that's at the absolute minimum of an intergalactic starship's practical mission duration.
It would be better than living your entire life in a literal cage on earth. But I think it would be worse than even being a slave on earth. A slave can touch grass and hope to run away. A person born on a generational ship would be effectively enslaved (to perform necessary ship duties). You mention 'cutting edge healthcare', but on earth that requires the substantial and diverse resources of an industrial civilization. The research of millions of people and the infrastructure to breed nuclides and manufacture precise machinery. Does this generational ship have a modern chip fab on it!?
I hate to break it to you, but that's also your current fate on Our Winnebago Earth.
Yeah but it's a BIG Winnebago.
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.
I’ve always wondered — magnetism seems kinda crazy — how are two objects not touching but exerting a force(?). Practically witchcraft…
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.
You might find this video of Feyman talking about magnets interesting: https://www.youtube.com/watch?v=MO0r930Sn_8
How is two objects not touching but feeling a force crazy? Isn't that what gravity does but everyone's ok with that
A lot of science is crazy but real. Are you not awestruck by the weird ways the real world behaves? Where's your wonder?
Gravity is crazy
And is a force only in the non relativistic model.
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.
Even the part accessable to just radio/light is small.
Tangential comment, but it’s crazy to think about how, when we look up at the stars in the sky, we’re seeing light in wildly varying degrees of age.
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.
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.
Light doesn’t age. From its perspective it hit your retina the moment it left the star.
Light is a wave, so it waves something to propagate itself in space and time. Physical photon does countless cycles to leave the star and hit an eye.
It's not an easy task from the prospective of a photon, which can be easyly proven with just two little slits.
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.
You are saying, from the perspective of light, whether it travels 1 mile or a trillion miles, that journey takes the same amount of time?
Yep, this is what he saying, but this is not what photon does. Photon must perform different amount of wave cycles to reach 1 meter or 1 trillion metters. These cycles can be counted.
I'm not a physicist, but I believe that's the exact insight that led to special relativity. It goes something like: If your moving at 1,000kmh next to a jet moving at 1,100kmh then the jet is moving at 100kmh relative to you. Eventually people realized those wasn't the case with light. No matter how fast the observer is, light still moves at 299,792,458m/s. Einstein figured out that if the speed of light is fixed despite relative motion, then time must slow down as you move faster. So from the perspective of a photon no time has passed since its departure.
I'd really highly recommend the Uncle Albert series of novels by Russell Stannard:
https://booksforkeeps.co.uk/article/visiting-uncle-albert/
The intuition you can develop about special and general relativity from these books is pretty amazing!
Nit: I think that the light from the sun is about 100k years old. Wild.
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.
How can that make sense, the photons are emitted and fly straight at us
The photons were created a long time ago in the core. It takes thousand of years for it to reach the surface, and THEN it takes 8 minutes to get to us.
Photons are not created on the surface but in the core where the environment has the higher pressure needed for the physical creation of the photon and the photon takes about that long to work its way out.
We live in a great neighborhood, but we’re behind on our HOA fees.
I love seeing sites like this! The formatting is very endearing to me
It should be a goal for Earth to send a probe to one of those stars. As the probe will be unmaned, a mission taking a hundred years or more is not out of question.
There are already plans to reach alpha centauri in about 20 years with unmanned probes (1). There still remain some technical hurdles in terms of the laser design to propel these probes afaik but it seems like this could be solved with more funding.
Too bad we are in the current era of eschewing scientific research in favor of crony politics.
https://en.wikipedia.org/wiki/Breakthrough_Starshot
This project is currently on hold, at least for the long-distance part.
https://www.universetoday.com/articles/starshot-not-get-a-re...
Something like Starshot seems like it could benefit from future developments without holding back a launch today. Something with a sail can always have a laser aimed at it; maybe we launch it today with a tiny laser we fire from orbit, and in 50 years, we accelerate them to a significantly better cruising speed by firing from a laser array on the moon.
Yeah given the current situation I bet China or India might end up sending those out before us.
Which, to be fair, is embarrassing for the US, but is just fine as far as species achievement is concerned.
Absolutely. At the same, I would love for U.S. embarrassment to spawn another "space race".
One issue with the latter is that tech is likely to advance fast enough that a subsequent probe launched a couple of decades later would overtake the first probe.
Regarding the former, various studies have been made and will certainly continue to be made: https://en.wikipedia.org/wiki/Interstellar_travel#Designs_an...
Exploration of the Very Local Interstellar Medium (VLISM) will likely come first: https://link.springer.com/article/10.1007/s11214-022-00943-x
I’d still settle for getting the probes out the door because no matter what advancement happens if you can’t get them into space it’s a moot point. I’d simply take something we can reasonably launch into space for research at this point.
Also, I would love to see a lunar base happen in my lifetime
Yeah, I don’t think it will happen that fast. There are a lot of hard problems to solve, and you have to make a case for the expected scientific (or other) benefits to be worth the costs. Look at how long the JWST took from initial planning to launch, that was about twenty years, despite clear and specific objectives.
That's not an issue. Thats a good thing!
Sadly if an alien civilization sent a probe to the Sun, would we even know?
Unlikely, but possible (if the probe was really big or really chatty in parts of the spectrum we pay attention to). Tiny probes could pass by us without us noticing them I'd think, though if they needed to send transmissions back toward their origin we might pick that up.
As someone who has been fascinated by the universe and galaxies from a young age, I too thought interstellar was the way to go. Nowadays, however, I've started to feel that we've been wrongly conditioned by science fiction to see interstellar exploration as the next logical step for humanity.
Our species is still very immature ethically, socially, and politically. We haven't even learned to accept each other and co-exist happily on Earth. Our distant hominin ancestors crossed entire continents but today we set up physical borders and cultural barriers to prevent even neighborly visits. We certainly won't become the broad-minded united ethical species that Star Trek TOS/TNG portrayed within the next 2-3 centuries.
Gradual spatial expansion, and through that, gradual cognitive and worldview expansion, has been our track record. Whenever things got hairy for someone in our hominin tree at any time, they moved just a little bit more to survive.
So, I feel exploring and settling other solar system bodies should be our next logical step. There are 4 solid planets, 5 dwarf planets, and as per Gemini, ~40 moons, ~3000 asteroid belt objects, and 200000+ Kuiper belt objects, all above 10 km radius. That's a lot of nearby space to explore and more practical than interstellar. Some of them will become the solutions or refuges from our current social and political problems on Earth.
It'll take us 1000s of years more, maybe even 100s of 1000s, to do all this. Including a lot of violence, conflicts and injustice. But eventually, we will learn to develop the cooperative institutions and cognitive/ethical frameworks we currently lack to become a multi-planet species. Interplanetary cooperative institutions and technologies will emerge eventually, just like today we have airplanes, the Internet, UN, WHO, EU - institutions and technologies that, while far from perfect, seemed downright unlikely for 100s of 1000s of years of our hominin history.
How would it be powered?
some combination of nuclear radiation and/or solar seems like it would fit the bill? 100 years is within the useful range of a large radioisotope generator.
https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_...
Solar would not work when you're out past Uranus or so, and the Sun is just a bright star with barely a visible disk. There's simply not enough sunlight out there, and you won't get enough light from your destination(s) star until you're similarly close to it.
RTGs lose power rapidly as the isotopes decay, and any sort of communication over those distances requires massive power. The Voyagers are essentially dead due to this issue, and they haven’t been out there nearly that long.
What about a fission reactor?
It would likely need a standalone fission reactor that only ‘goes hot’ when it arrives.
I’m not sure that we have the engineering ability to actually do that with any real chance of success after a 100 year deep space flight, or the willingness to wait that long to find out.
That runs for dozens of years without maintenance? And how do you dissipate the heat?
Open the rear end and you get propulsion as well. Just don't start close to earth
That's the neighborhood. Maybe two stars might have planets that could support life. Maybe.
I swear there used to be a 3d map that you could navigate, rotate zoom in zoom out of local space, but I can't find it anymore.
Does anyone else remember that or am I imagining it? I think it was like 10 years ago
are you thinking about 100,000 stars? https://stars.chromeexperiments.com
Stellarium? https://en.wikipedia.org/wiki/Stellarium_(software)
Celestia https://celestiaproject.space/
There are attempts, but they all suck IMHO :( Someday I'll get around to doing this in Three.js for real, if no one beats me to it. It's shocking that we have a million 3D sites to visualize LEO satellites and plenty to visualize the solar system, but our stellar (much less galactic!) neighborhood is all super outdated stuff only.
I guess the sad reality is that these tools aren't that useful for anything but diagramming the odd interstellar rock.
https://www.reddit.com/r/askastronomy/comments/1bhklhd/what_...
https://chview.nova.org/solcom/index.html
edit: crossreference with https://gruze.org/galaxymap/map_2020/
I can barely read the stars' names, this font choice was a mistake.
1995 website.
I immediately opened the view-source .... it was all tables.. so yes.. a confirmed 1995 website :)
It's a map, and a time machine!