The Universe Within 12.5 Light Years
atlasoftheuniverse.com
atlasoftheuniverse.com
If you go close enough to the speed of light, what you actually see is that space appears to shrink (in the direction of travel) and the trip seems to take less time than light would, because you've apparently covered less distance. Of course what those on the planets would see is that time has been moving oh so slowly on your otherwise speedy ship. There are equations you incorporate into a simulation that would account for this. If the game mechanics were such that you could could see what day/month/year it is in local time, vs your ships time, it would quickly become apparent that bashing through the void is no way to get anywhere.
Time dilation is just shortcut to say you are no longer sharing the same frame of reference. If everyone has their own frame of reference there is no difference between single player game and multi player one
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.
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.
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.
But I absolutely loved the show growing up so not here to knock them. I am sure in hindsight they may have come up with a better definition of how warp speed works and how they can travel great distances. I won't think about it too much.
This just shows a juvenile and naive level of thinking. You can't spend 72,000 years with our current brains in full conscience without going insane.
I'm not sure if the CMB itself will decay fast enough with the expansion of the universe to avoid 1g eventually getting you hull eroded by positron-electron pair production from photons blueshifted above 1022 keV, but that's in the set of things you need to think about.
I have never seen anyone writing about us having solid reference points to travel that far in case we can reach those speeds.
If you miss you end up in some empty space you won’t be able to mine anything for fuel to have more shots.
Estimating time-to-arrival when your destination is also moving at ludicrous speeds is incredibly difficult.
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?
However say red dwarfs with moons of closely orbiting gas giants, and many other combinations could in theory be sustain life easily .
We can learn from history on earth, economics is the reason why cities or outposts form and die, even when they are very hostile or very unsuitable and expensive to make it work.
Space would be no different, people would be happy to setup an outpost on Betelgeuse despite its impending supernova if they can say get away from regulation or it cheaper to make things for some other reason, or there is ideal low gravity planet with the right conditions for growing some thing even it would normally be considered hostile .
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.
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.
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
Fixed that for you. Rev up those stealth fighters!
I'd expect that the time scales between spurts, while getting shorter over the past 350 years or so, were generally much, much longer.
We first started using stone tools more than 2.5 million years ago. We didn't start effectively using fire for another 500-750k years.
It was another 1.75 million years before we began harvesting seasonal "crops" we identified in our nomadic travels, and another tens of thousands of years before we founded permanent agricultural settlements.
Doing so (and the food surpluses enabled by such) allowed for specialization and R&D into stuff that wasn't directly related to food production.
That really kicked off a technological spurt, which included writing -- a technology that was, perhaps, the biggest step forward, until Liebniz/Newton's Calculus.
Given the immaturity of our current understanding of physics (Standard Model/General Relativity), biology (DNA research) and the like, it seems we're likely to continue without another spurt for quite some time.
I, of course, could be wrong. But since history is often a good guide to the future, I don't think so.
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.
Currently focusing on imaginary money crypto schemes and ML chatbots whose data centers use as much power as entire US states, sorry.
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.
Physical world is big and getting from one point to other takes lot of energy and involves lot of mass.
(Big IF there, I know)
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.
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.
Not that humans with their troublesome egos are necessarily anywhere near global maximum.
But even that doesn't guarantee anything. Modern humans are ~100k years old. It took us nearly all of that time before we discovered agriculture. And it still took thousands of years after that to end up with industrialization. Before then our societies barely improved. It's entirely possible that if society had gone differently that we could've delayed or avoided industrialization altogether. The same could've happened with dinosaur-people.
“The next step is crucial. The simple organic molecules have to be shielded from the ultraviolet radiation of the primary. That requires a large body of water—an ocean—to protect them. No protection and the molecules break up as soon as they're formed. And oceans of water are … extremely rare.”
…
“But something else is rarer still. The next step in the creation of life is when the amino acids form into long chains.
Left in the ocean, they drift apart as easily as they join together. There has to be a means of concentrating them. Once a certain level of concentration is reached, they'll form long chains, more complex molecules, automatically. Heating isolated bodies of water would help, say tidal pools warmed by hot lava and occasionally replenished by the sea.”
…
“Do you understand, Sparrow? Tidal pools implies tides and that means a moon large enough to raise them—though not too frequently, because you might dilute the pool too much. A combination of the primary and the moon would raise larger tides less often, and that would be a happy medium. What's required, then, is a planet that has land surfaces, oceans, and a large enough satellite to raise suitable tides. The action would concentrate the simple amino acids and they could combine into the longer chains.”
The novel is The Dark Beyond the Stars, and I recommend it highly.
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.
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.
"It is inconceivable that inanimate Matter should, without the Mediation of something else, which is not material, operate upon, and affect other matter without mutual Contact... That Gravity should be innate, inherent and essential to Matter, so that one body may act upon another at a distance thro’ a Vacuum, without the Mediation of any thing else, by and through which their Action and Force may be conveyed from one to another, is to me so great an Absurdity that I believe no Man who has in philosophical Matters a competent Faculty of thinking can ever fall into it. Gravity must be caused by an Agent acting constantly according to certain laws; but whether this Agent be material or immaterial, I have left to the Consideration of my readers."
https://plato.stanford.edu/archives/win2008/entries/qm-actio...
What I was trying to get at is I argue that historically we had no reason to assume magnets to exist until we discovered them. (Sure, today we can explain them in terms of the effects of electrons traveling at relativistic speeds.)
It otherwise seems a safe assumption that we cannot move into a 4th spatial dimension (even if such exists) or do many other outlandish things. I don’t think we can prove them impossible but likely just don’t know how.
But imagine if Newton had been shown an electromagnet and asked to explain it… It would have been witchcraft!
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.
I believe historically it was either for profit, which there is unlikely to be much in medium term. Or because the new place was expected to be better. Mostly due to resource constraints. But generation ship should be quite optimal. And well outside magic level tech there is not much to do on empty planet.
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.
So there must be a range in age. As some closer to still hot surface don't need to travel through parts of the sun.
I knew HN would nit my nit, well done!
https://booksforkeeps.co.uk/article/visiting-uncle-albert/
The intuition you can develop about special and general relativity from these books is pretty amazing!
In a lab setting, yes, but across such distances, no. Photons don't have a cycle counter on them, so they don't keep a cycle count and can't reveal that cycle count. All we can do is measure frequency/wavelength (spectrum, really, since we're going to see lots of photons, not really onesie/twosies) and intensity, and we can use the astrophysical distance ladder to figure out roughly where the emitter must have been.
There's also a different thing that GP might be hinting at, which is that by convention we assume that the speed of light is the same in all directions, but there are other conventions we can use as long as the round-trip speed of light agrees with that which we've measured (and yes, we can only ever measure the round-trip speed of light, FYI). Another convention is that all the light we see takes zero time to get to us but the light we emit goes out at half the speed one would expect with the standard convention (known as the Einstein synchronization convention). So instead of "light we see from Alpha Centauri is 4 years old" or "we see Alpha Centauri as it was 4 years ago" we can say that we see it as it is right now, but this is not a very commonly used convention.
> we can only ever measure the round-trip speed of light, FYI
Therefore you can't measure the speed of light in any one direction. You can only measure the round-trip time of flight (e.g., if you have the detector at the emitter and use a mirror).
So a photon emitted in such a direction takes no time (from the photon's point of view) to be absorbed by its destination... only it has no destination and never will. It gives "what if a tree falls in a forest with no one to hear it?" vibes. Does the universe sort of "lose" the energy of that photon in a way that it doesn't for photons that are absorbed? Is it like The Great Memory Leak of the Universe or something? Is our existence leaking out between the fingers of the hand of God?
It's not an easy task from the prospective of a photon, which can be easyly proven with just two little slits.
Experiencing time and having mass are linked in a very deep way. Objects that experience time, i.e. have some kind of state evolution, must have mass, this is how we know the neutrino has mass even though it's smaller than we can measure, because we measure them oscillating between the various flavours of nutrinos.
This is also how the Higgs mechanism gives rise to "rest mass" in most particles, by constantly exchanging weak hypercharge with them. This oscillation back and forth gives them mass.
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.
Does anyone else remember that or am I imagining it? I think it was like 10 years ago
I guess the sad reality is that these tools aren't that useful for anything but diagramming the odd interstellar rock.
Notably, Luhman 16, which is just 6.51 ly away, but is so dim and in such a crowded patch of sky it was only discovered in 2013: https://en.wikipedia.org/wiki/Luhman_16
https://en.m.wikipedia.org/wiki/Radioisotope_thermoelectric_...
Which is an interesting thought when considered as a weapon. Fire a self-immolating fission reactor at your target...
Also, if there are aliens there, sending a highly radioactive blob of plasma at them at interstellar speeds might cause a little trouble.
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.
Too bad we are in the current era of eschewing scientific research in favor of crony politics.
https://www.universetoday.com/articles/starshot-not-get-a-re...
Sadly, that also means you have to accelerate them hard if you want to get to a decent fraction of c before they're effectively out of range. Which means your solar sail has to be really, really tough while being really, really light.
I have no idea what the best-case scenario for laser acceleration is.
Let's say our initial boost got it up to 0.1c. After 20 years, it's gone 2 light years. If we make our space-based laser aperture really big, let's say 1km, then the light reaching our probe is something like a 25000km wide radius. That's not going to power anything.
If you slow down the initial 0.1c, then pretty quickly you're better off not sending it out at all and getting a bigger boost from your giant space laser being close for the initial acceleration.
The diffraction limit is annoying.
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
Also, I would love to see a lunar base happen in my lifetime
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.
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.
Most of the imaging and signal-processing tech built for astrophysics ends up in medicine, satellites, and everyday devices. The "wow" factor funds a lot of spinoffs.
Space weather doesn’t stop at the edge of the Solar System. Supernovae, stellar motions, even rogue objects can affect us. Better to understand them early.
It’s long-term thinking. Nobody builds interstellar ships tomorrow, but mapping the neighborhood now is how future generations avoid starting from zero.
Honestly, it also grounds us. Realizing Earth is one small rock among billions changes how seriously we treat our only habitable home.
Basing an inertial coordinate system on the observed positions of the bodies belonging to the Solar System is affected by much greater errors caused by the imperfect modeling of their relatively fast movements.
Using stars that are outside the Solar System is much better, but using distant extra-gallactic objects is even better.
If we did not have the "fixed" stars as a background on which to view the movements of the Sun, Moon and planets, who knows how many centuries later physics and technology would have reached the current level, because when seeing only the relative motions of the planets, without a fixed reference system, those are much harder to understand.
For interplanetary navigation, receiving signals from pulsars can be used as a backup or a replacement for atomic clocks. Individual pulsars, especially when young, are sometimes affected by "glitches" when their moment of inertia, thus the frequency of their signal, changes, but if multiple old pulsars are monitored, any glitches should be detectable and they should not affect operation.
Even the primitive humans of many thousands or tens of thousands of years ago knew to predict seasons by observing the rising stars and to navigate with the help of star gazing.
For the ancient civilizations dependent on agriculture, observing the stars, e.g. to determine when to sow various cultivated plants, could have a life and death impact, not a minor influence upon their life.
Wikipedia article: https://en.wikipedia.org/wiki/Near-Earth_supernova
Kurzgesagt video on the impact on Earth of supernovas at varying distances: https://www.youtube.com/watch?v=q4DF3j4saCE
As the Kurzesagt video points out, a supernova within 100 light-years would make space travel very difficult for humans and machines due to the immense amount of radiation for many years.
Still, I think the primary value is in expanding our understanding of science and the nature of the universe and our location within it.