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

Totally.

The Milky Way is on a collision course with Andromeda, so we are already on our way!

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.

Not for humanity, not as we currently understand ourselves as humans anyway.

I suppose it all hinges on what humanity manages to figure out, physics-wise. I like to keep the door open

No, not unless we have made some serious mistakes in our understanding of physics.

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:

1. Upload conciousness into computers, leave physical bodies.
2. Miniaturise computers until we have spaceships in the grams/nano grams
3. 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.
4. 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.
5. 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)
6. 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.

Nope

No, I genuinely don't believe it will. I don't think the human race will ever reach another star, though I do believe it could be possible if we avoided going extinct for a few thousand years.

Another galaxy? No chance, not unless we figure out FTL, which I don't believe is likely. The only FTL I've heard of that might be possible is the Alcubierre drive, but it relies on things that are so exotic, it's likely impossible to create one.

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^2

s: 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.

Everyone here saying confidently "no" hasn't kept track of science over the last several thousand years. There have been hundreds/thousands of things that have been "that is impossible" that we simply didn't have the knowledge for to be able to do.

200 years ago you would have been laughed at for thinking man could ever take to the skies, and now flying is a boring tedious thing for us.

75 years ago the idea of carrying a computer in your pocket with thousands of times the sum of the entire compute availability in the world back then would have been scoffed at, and people would have told you it's impossible. Now we use it to post on forums like this like it's nothing.

Both are examples of "it's impossible, the science says so", but that's the neat thing about science. We learn new things every day. Our thoughts change, you don't "believe" in science, you only learn new things.

So is it impossible? I think it's incredibly small-minded and dare I even say arrogant to say it's impossible. How do we know what will be discovered tomorrow, or 100 years from now, or 1000 years from now? We have absolutely no idea what will be possible then. With our current technology? Absolutely not. In 400 years? Who knows someone may be standing in line at security and see a meme making fun of us for thinking it was impossible.

The kind where one can get to a different galaxy in a single lifetime? I doubt it.

With our current understanding of physics it is impossible. Sucks, I love sci fi but they all rely on inventing some magic machine to make it possible.

Speed of light limitation. Andromeda is 2.5 million light years away. Even if someone debunks special relativity and finds you could go faster than light, you would be moving so fast relative to cosmic dust particles that it would destroy the ship. So, either way, you cannot practically go faster than the speed of light.

The only way we could have intergalactic travel is a one-way trip that humanity here on earth would be long gone by the time it reached its destination so we could never know if it succeeded or not.

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....

Depends how long you have. 

I hope we come up with warp drive or something crazy, but technically I don’t see any way this happens. 

But if we could, we would ruin wherever we find habitable, and it would be the impetus for us to totally trash the Earth because suddenly it’s disposable and we can just go to Elysium or whatever other place. 

We’d find planets and just fill them with toxic waste factories, because who cares, “we” (the rich) don’t have to live there. 

We’d take visa scams to the extreme, forcing people into slavery on planets they could never escape from, and quash uprisings with bombs or stranding the people there. 

Humans are too greedy and flawed. 

I can picture the possibility of a probe visiting our nearest neighbors

• https://en.wikipedia.org/wiki/Breakthrough_Starshot

But there are so many problems with a generation ship going that far, and no, none of the fun sci fi ways of travel are possible.

Bringing this back to reality, I can definitely see exploring more of the solar system and I can see making use of resources on hand for bulk consumables like fuel, oxygen, water, housing (we’ll have to to make it work). But consider how many things it would take to actually be independent of earth and how large the colony needs to be. Remote bases in our inner solar system can get away with that, but you can’t leave the solar system and expect to rely on any resupplies from earth.

Even if you could achieve the travel time to visit another star system and build a generation ship with enough supplies of everything and that could function that long, how would you survive without a preexisting functional colony of millions of people? Just start with the thousands of types of plastics we use every day and imagine trying to support that for a few people, without oil to drill or other organic chemicals to mine, and without a full scale chemical industry

i think we'll destroy ourselves before we get that far

I sure hope not

If we weren't busy squabbling like neanderthals about who has a bigger stick and joined together we could have already come to some form of interplanetary travel and possibly colonization of other planets in the solar system but we're too busy fighting over this tiny speck of space dust to focus on anything else.

It's already possible in a "does it violate the laws of physics or not" sense, the real question is, will anyone that has the requisite resources to do it actually want to.

It would take such an incredibly long time (as in, millions of years or longer for the very closest galaxies) that anyone and any organization sending out such an expedition isn't going to get any meaningful return on their investment, so it would only bring a benefit to whoever was on the "ship" when it arrived. As such, to even have a motive for doing this, you either need a society that does things for the benefit of extremely distant descends, or which is extremely long lived and patient.

As to how you would actually do it, my guess (obviously though, the guess of someone from a society that lacks the technology to do a thing is likely to be wrong about how it later is done) would be that one would use a hypothetical type of structure called a stellar engine These are similar to the "dyson spheres" that science fiction sometimes likes to talk about (usually inaccurately to the actual concept but still), except that they would use the energy emitted by a star, or its mass, to do some particular task, like propel the star in a given direction.

Doing this, your "ship" is actually an entire solar system. Getting that up to speed could take millions of years even for the most efficient designs, and obviously requires an economy capable of building stuff at incredible scales, and having an entire star spare to use for the trip. However, you're going to be taking that kind of time anyway, and so you're probably going to need an entire self contained civilization to have a hope of keeping things running that long, and literal worlds worth of raw materials. There's not much else that even theoretically has enough fuel to move all that to notable fractions of lightspeed. Since there's little point to going to live in another galaxy if there are still unclaimed places to go within your own, a whole star system is probably a relatively small expense for the implied size of civilization that would even want to try to sebd such an expedition. Galaxies contain a huge number of them after all.

While this is all obviously far beyond us now, both in technology and sheer economic scale, there's nothing physically impossible about it, and at least some logical motive (the future resources of a galaxy for one's descendants, if alien life is rare enough for uninhabited galaxies to exist). Given that and just how huge the universe is, I'd actually be willing to bet that somewhere there is someone or something doing this, and that if humans last long enough and keep advancing our technology and infrastructure all the while, some descendant of our species might, though they'd probably seem pretty alien to us by the time it took to reach that point.

Forever is a long time.

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".

Possible? It's possible today!

I think it's just an engineering and more likely a desire problem right now. It is expensive to get things into orbit and we just haven't studied what other problems will arise.

If you mean faster than light speed, there is some intriguing things in physics but with our current understanding no we cannot move massive objects faster than light.

There are still a lot of gaps in our understanding though so perhaps we will learn that it isn't impossible.

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.

Absolutely.

What form it will take is the question. FTL, not likely but long ago we didn't believe in breaking the speed of sound. Generation ships, solar sails, ion drives, folding spacetime, it will happen somehow if we survive as a species.

Well I wouldn't say it's completely impossible. A lot of technology exists that would have been seen as impossible in the past. But I think intergalactic travel is extremely unlikely. I can't imagine that we will ever create ways for the human body to withstand long distance travel as portrayed in shows like Star Trek

No. Never.

yhea, but that depends on timescales and if we don't kill ourselves.

I mean Im not even sure we will have planetary much less intergalactic. I mean like one offs sending people to some other planet. Im not sure that counts anymore than voyager would for interstellar. I mean I do think about it. Intergalactic, planetary, planetary, intergalactic.

It already is and so is time travel but you wouldn't believe someone on the internet?

Not at all. But can we volunteer some people to go up and try it?

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.