[arkaic]

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.

[o11c]

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").

[bartvk]

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?

[manquer]

If you want to exact match to earth in our solar system line conditions , i.e. G-5 star with a rocky plant in the water zone and not too close to a binary if any - you would end up with only few possibilities in 1000Ly

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 .

[bartvk]

Thanks so much, I love your comments here!

[iambateman]

Your writing style reminds me of Brandon Sanderson

[xboxnolifes]

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.

https://youtu.be/uUuM8NdmaAU?si=7It672waw734e9nK

[mr_toad]

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.

[manquer]

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.

[AngryData]

In the Foundation series the old empire's central planet Trantor was just one giant city that did almost nothing but administrate the empire.

[IAmBroom]

"All these worlds are yours except Europa. We keep our old tax receipts there."

[hopelite]

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?

[14]

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.

[watersb]

> 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.

[14]

Yes I think you are spot on, they move at the speed of how fast the plot needs them to move. After posting my comment and looking online at some suggested speeds for the various warps speeds it is very inconsistent and far from realistic given the size of the universe. One would need to be able to travel at something like 100,000 times the speed of light to realistically travel just around our galaxy. Probably would need to travel at about 1,000,000 times the speed of light wanting to make it to the next galaxy in a realistic time. Even at 1,000,000 times the speed of light it is going to take years to just reach the next galaxy so it is no where near fast enough to get around like they did in star trek.

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.

[jl6]

It’s not that light speed is too slow, it’s that our lives are too short. If you can solve mortality, you just hop on board your 17km/s ship, turn YouTube on (all of it), and spend a relaxing 72,000 years getting to Alpha Centauri.

[danielheath]

If you accelerate at 1g half way there, then decelerate equally fast for the second half, you can reach almost any point in the galaxy in a single human lifespan - thanks to time dilation.

[ozim]

Obviously just don’t forget aiming for where we see it now is not where it is and not where it will be in 100 years.

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.

[actionfromafar]

Stuff keep moving predictably. Plus you can course correct during a fair bit of the acceleration / deceleration phase.

[ben_w]

Just remember to account for blue-shifted CMB.

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.

[Scarblac]

Is it possible to take enough fuel and mass with you to accelerate that long without turning into a black hole?

[MichaelRo]

>> and spend a relaxing 72,000 years

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.

[DonHopkins]

I Hope I Shall Arrive Soon

https://en.wikipedia.org/wiki/I_Hope_I_Shall_Arrive_Soon

[jl6]

> current brains

[greenbit]

Are we nearly there yet?

[MichaelRo]

We live to 72 on average so only off by a factor of 1000x :)

[Anarch157a]

That is assuming the objects will be at the same place relative to us, which is not true. Like reaching Andromeda. Voyager I will reach oyr neighbouring galaxy in roughly 4.5 billion years, not 45, that's because Androneda is moving in our direction. Reaching Proxima Centaury would take longer than your estimation because of it's orbit around Alpha Centauri A/B.

Estimating time-to-arrival when your destination is also moving at ludicrous speeds is incredibly difficult.

[wakeforce]

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!

[pavlov]

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.

[mr_toad]

Jupiter is between 4 and 6 AU from Earth. So at the speed of light it would still take over half an hour to get there. It’d be a dull game flying anywhere at sub-light speeds.

[pavlov]

It’s been over thirty years since I played Frontier, but I think you could accelerate the in-game time. So you didn’t have to sit still for hours to get to Jupiter. For your character, that time did pass.

[davedx]

Yup that’s how it worked - there were several time advance multiplier buttons. Anytime an enemy ship engaged you it forced you back to 1x time, annoyingly

[baggy_trough]

I suppose they can’t simulate time dilation, which does make it possible to visit other galaxies without FTL.

[greenbit]

You certainly could simulate time dilation, I'd be surprised if that isn't already an element of some game out there.

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.

[mr_toad]

You couldn’t simulate time dilation in a multi player game, at least not in any way that didn’t involve some players waiting for others.

[nilamo]

Sure you could. Each local area (such as a planet) is a single timezone, and everyone there experiences time at the same rate. Someone leaving that timezone would experience time dilation... But in game it would just appear as a communications lag, just as it is for people on different planets. Then, once you've arrived at your destination, there's no longer any lag with your new timezone, and your lag with the original time zone is now fully synched with everyone else on your new planet.

[luxpir]

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.

[Martin_Silenus]

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.

[codesnik]

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?

[baq]

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.

[7373737373]

Space Engine is excellent for this too