Greg Egan’s Diaspora sets out how humanity could explore the galaxy and even the multiverse, which if you can’t be bothered reading consists of:
- Upload conciousness into computers, leave physical bodies.
- Miniaturise computers until we have spaceships in the grams/nano grams
- As we’re no longer connected to time we can build massive solar system sized technologies, built by nanotech, that sure could take hundreds of years to build but in our virtual realms we could easily sleep.
- Use Lasers to propel our nanogram spaceships to 90% light speed. Even then for the astronauts, time is almost nothing (time goes slower the faster you go). A trip across the galaxy would feel like mere weeks to you. We could explore the universe as immortals.
- At this point we should have a pretty good understanding of dark matter/energy and how to move between universes (the multiverse, depending if you accept it as a base for explaining non locality)
- Which would allow us become eternal.
In the here and now the only way to travel to another system with our current tech is via nuclear pulse engines.
Basically you build a large spaceship. Stick it on massive shock absorbers which are in turn connected to a metre plus thick steel plate.
Cut small hole in the middle. Have a door that opens closes.
Eject 1kt explosive device out door. Repeat 500x till you get to orbit.
Basically you could get a spaceship up to very high speed with nuclear pulse engines to turn a multi hundred year journey into less then 100 years.
That said the biggest problem with interstellar journeys is that our material science and manufacturing tolerances are pretty shit. Essentially all of the air will leak out through the metal skin of the spaceship.
I still think carving put an asteroid, sticking engine on it (see nuclear pulse engines) , covering it in ice and water will solve the problems radiation shielding, losing critical gases and provide ample fuel and water for a very long journey.
The big problem is energy. If we had almost infinite energy we could accelerate to a significant fraction of the speed of light at a leasurely 9.81 m/s² in about a year. The travel at almost lightspeed would feel instantaneous for us. Add another year to decelerate at the same rate. We could reach any point in the visible universe in 2 years.
Our destination would just be drastically different from what we observed, depending on how far away it was.
Oh, and apart from the tiny energy problem cosmic radiation will probably destroy our spaceship. I bet at relativistic speeds you’d even get enough neutrino collisions to make them a problem.
I think it is more a question of will we make it that far. If so then it should be possible but I don’t expect it would be the norm and likely single way. Communication back home would be almost pointless due to the distance.
Perhaps it will be like the Rimworld lore. FTL is never achieved, civilisations are unable to remain stable once communication takes more than a few years or decades between planets as culture drifts over time. This doesn’t prevent intergalactic travel but it does make it a one way colonisation mission.
There is another layer. You are not only trying to travel through space, but also time.
We know the formula:
s^2 = (ct)^2 - d^2s: spacetime distance/interval (invariant no matter the observer)
c: speed of light
t: time
d: coordinate in 3D space
Now, let’s say we have 2 travelers who need to meet at a certain place. Traveler A is 1 spacetime distance unit away Traveler B is 2 spacetime distance units away.
If they are both at the same age when they started the journey, B would be younger than A even though A is closer to the destination than B! Because B experienced more time dilation, and A needs to either wait at the destination, or travel slower.
So to meet each other at a relatively same age, B needs to travel slower on purpose, or A can take a detour.
Millions of years become meaningless, people who have no spaceships would be a death sentence. They would never see loved ones again. So in a sense, enormous ships that can travel at near the speed of light are a norm for that type of civilization.
We are unfortunately at a very early time of the universe. If we are born later, we could probably see other civilizations travel to us :D
Space travel is weird. Brain hurty.
Yes
I know enough physics to say no Even inter-Stellar is out of our reach (without generation ship).
We have zero reason to believe in an effective way to build wormhole, jump gates or anything similar. Even high energy cosmic rays have a limited range (due to collision with photons) which is a strong clue that there is no shortcut in space
Fuck it, let’s assume we can build jump gates.
Let’s say they’re just big enough to send a tiny unmanned drone through.
I hop into my space ship and accelerate with a conventional engine to 86% of light speed.
No violation of physics needed, just shitloads of energy.
I fly to another star, which takes 10 years from earth’s point of view.
Due to time dilation at 86% light speed, time in my space ship passes half as fast as on earth.
If someone on earth had a strong enough telescope, they could look at a clock on my ship and see that it ticks half as fast as the clocks on earth.
But in my frame of reference, earth moves away from me at 86% light speed.
So if I look at earth through a telescope, I see that the clocks on earth tick half as fast as mine.
There isn’t a universal time. Time is always relative to speed and this is no problem when the reference frames are separated.I arrive at the star, after 5 years have passed on earth.
I activate a jump gate and send the drone through with a message. It arrives on earth instantly, 5 years after I left.
But from their reference frame, they could see my clock ticking only half as fast as theirs.
After earth’s 5 years, only 2.5 years have passed for the space ship they see.
They activate their jump gate and send the drone back with a reply.
It arrives instantly at the star, 7.5 years before my space ship gets there.This is why FTL travel isn’t and will never be possible. Even with tricks like jump gates or wormholes, it creates time paradoxes.
Assuming a mechanism exists that changes the universe from being singly connected to multiply connected (i.e., wormholes exist), it is possible to have wormholes permitting faster-than-light travel without time paradoxes, though some additional restrictions may apply.
We have already shown that wormholes connect across both space and time, so that a trip between star systems could take you hundreds of years into the future, and the return trip takes you hundreds of years back in time. And this is even before we throw in how time slips between planets when considering relativistic time dilation due to different speeds and gravitational potentials.
Fortunately, all the weirdness of different time rates and going backward and forward in time can be ignored by the average person. This is because you never need to go from one world to another, or back, across the vast gulfs of interstellar space. You just take the wormhole between them. All you ever need to worry about is the coordinate frame that goes across the wormhole. When considering this reference frame, you’re not hopping all over the place in time. If it takes ten minutes to cross the wormhole between the two planets, when you get to your destination world the clocks will read ten minutes later than they did when you left your departure world. By coordinating their time-keeping across the wormhole network, all of the worlds of the network can agree on a common time to coordinate their activities. This is all travelers ever need to worry about, and they can then ignore all the relativistic weirdness. Your network engineers will still need to keep track of relative time drift and how close a given configuration is getting to a time loop. But unless your protagonist is a network engineer, they can just ignore all that stuff. And, as an author, so can you! Assume your engineers are competent, you have good regulatory bodies and standards institutions, and don’t worry about any of this “time travel” that doesn’t actually let you cause paradoxes.
This is the correct answer.
I think the closest we will come is detecting radio signals from another species. But like obviously 2 way communication would be almost impossible due to sheer distance.
the closest we will come is detecting radio signals
But we are talking about intergalactic here.
Radio is only lightspeed, and that is much too slow to cover such distances.
Sadly the universe is filled with enough random radio radiation that its unlikely any coherent signal is going to travel more than a few light years. With our current technology there could be an identical version of earth around the nearest star and we probably couldn’t detect it.
The signal isn’t destroyed though. So one could argue that isolating it in the noise is doable with enough math.
Obviously the real limit is still distance since we’d need a radio dish like the size of earths orbit or something to pick up a signal weakened from many lightyears away.
Probably with virtual telescopes, smaller receivers arrayed throughout the entire solar system, like EHT but biiiiiiiigger
But doesn’t the generation ship / cryogenic technology / nuclear technology make intergalactic travel possible (albeit very slow)?
The very slow is the issue. Assuming we can reach 10-20% of c, we can reach a couple of nearby stars in 200 years (Wikipedia gives me 50 stars with 30 ly).
200 years is roughly the time from the Napoleonic era from today (Taking an Euro reference). Do you remember what your ancestor were doing during Napoleon Russian campaign or when US purchased Louisiana?
Society changed massively since Napoleon. Over 200 years the society culture of a generation ship would also drastically diverge from ours. Moreover, I can’t think of many piece of technology which can keep working for 200 years without a few massive overall.
In theory yes… but the oldest frozen specimen of humans we’ve found is only a few thousand years old. We don’t even know if long term cryogenic reanimation is possible.
Assuming the ship travels at 10x our current capabilities we’re still looking at ~8,000 years to reach our closest stellar neighbour at only 5 lightyears away.
Then don’t do it that way, put a human consciousness into a machine and wait. They said ever, we can get as sci-fi as we want here
We’ll still run into the same assumption/problem; shelf life.
Consider how memories work. Every time you remember something, your brain alters that memory slightly. Even looking at how the brain parses the data through several cortex (visual etc) implies that consciousness is potentially inseparable from the components of the brain. In this video about Cockatoo intelligence they speculate that birds brain anatomy causes them to think in ways that seem limited to us.
Basically we don’t even know if its possible to preserve human consciousness for that long. Similar to cryogenics we have to question if reanimation is even fundamentally possible after centuries.
It’s a simulation of a human consciousness, it can be paused and restarted when certain conditions are met.
It makes interstellar travel plausible but not intergalactic.
You are talking about a trip that would last longer than human civilization has existed.
Sort of - but there is no reason to think we will ever be able to make something that won’t break. Even intersellar is questionable just because the odds of the ship breaking in the time needed are too high.
Totally.
The Milky Way is on a collision course with Andromeda, so we are already on our way!
Maybe Andromeda is coming to save us. Isn’t that what The Andromeda Strain was all about?
You are confusing that with Galactica from Andromeda out of the “Hello Spencer” TV series.
The “Andromeda Strain” was about human hubris and the reasons we are probably not going to become intergalactic travellers…
That reference was a bit strained.
That was an interesting mini series, albeit nothing to do with Andromeda Galaxy.
I wondered why I didn’t remember a mini series to exist - then saw its Rotten Tomato rating…
So perhaps better watch the film instead.
It has a few 60s movie moments, but overall was really fun to watch, with most of the science being surprisingly solid, given its age.
With a generational ship and a shield and a way of blocking cosmic rays I think it will eventually be possible, but take a very long time. I don’t believe light speed will ever be possible, but going near light speed starts slowing down time a whole bunch for those on board the ships. So if for instance we came up with some trickery to get up to 99% the speed of light and wanted to go to a planet one galaxy over that’s 25,000 light years away, in theory the ship and the people in it would get there in about 1200 years. Even though it would be like 25,000 years for anyone who wasn’t on the ship. At 99.999% it would only take what would seem like about 115 years on the ship.
I’m not going to say that’s flat out impossible that it could happen but we’d have to find one hell of a way to cheat the system.
Alternatively, I think it will come about (if humans don’t kill ourselves off) that a person can “live forever” in one form or another. If we get to that point then pesky things like travel time and atmospheres and such will be much less an issue. I then wonder how long a person would want to be around before they decided they’d rather “self terminate”.
Probably not. Main problem is energy density.
Theoretically we could visit things thousands/millions of light years away within a human lifespan, but the necessary energy to do so is just infeasible. You’d have to spend half the energy slowing down at your destination so you’d need all that energy onboard. Just not happening IMO. As a bonus you’d basically also be inventing a time machine (forward only)
Interstellar travel? Like to the nearest star systems? Maybe. In the far future. But not intergalactic. Andromeda is the closest galaxy and it’s 2.5 MILLION light years away…
I suppose it all hinges on what humanity manages to figure out, physics-wise. I like to keep the door open
Other stars are at least a thousand times as far as distant planets, but other galaxies are only about 4 or so galaxy-widths away on average. So if distant interstellar travel is possible, then intergalactic travel is just a hard trip away. The problem is that statement continges on a very large “if”.
Humans? Nope. Some kind of actual AGI that doesn’t care about long time scales and can be lashed to a metal rich asteroid and flung out of the solar system? Still probably not, but it could maybe make it to some interesting intra-galactic destinations.
This is basically the foundation for Stanislaw Lem’s book The Cyberiad. What if robots built robots that write poetry and fight robotic dragons and travel the stars.
Also the Bobiverse books. Human brain uploaded to a machine and strapped to an engine to sail the stars where stuff happens
Ooh! I love Lem! I do recommend him for any sci-fi lovers.
yhea, but that depends on timescales and if we don’t kill ourselves.
No, not unless we have made some serious mistakes in our understanding of physics.
I would say it’s pretty likely that we have made some serious mistakes but also probably not possible.
Nope
