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.

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.

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…

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

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

1. I hold that the physics this world’s establishment holds-to is obviously flatland “physics”, as it doesn’t include mind/will, and you CAN’T have real physics, if you’re handwaving & saying “oh, but those phenomena aren’t really real”. The fact that … Jacob? ( see Curt Jaimungal’s videos, on yt ) discovered that the difference between statistical-probability theory vs quantum-probability theory, is that quantum-probability includes knowing. Knowing, aka “information”, as physicists call it, is physics-real. Pretending that information is real, but knowing isn’t, is … defective. Pretending that knowing is real but mind isn’t real, is absolutely shameless. Ideological-prejudice is what’s really going on. Look for the “Non-Markovian” probability video, & you’ll see it spelt out plain as day: knowing is physics-required.

2. The fundamental-technology should be possible, but the durations might be absurd.

3. the way it works is this:

Speed-of-light-limitation is WITHIN a given SPACE.

So, if you’ve got time & multiple different 3D-spaces ( think leaves on a branch: each leaf being a 3D-space ), then the speed-of-light-limitation in EACH is limited-to limiting speeds in THAT space:

There isn’t any speed-limit BETWEEN spaces, see?

So, “rotating” from another space into OUR space, then moving 100km within our space, then “rotating” back into their space, means you’ve now moved 3 parsecs…

Simply because our 3D-space & their 3D-space don’t happen to be at the same “angle” to the universe’s underlying-structure…

then travel which is simultaneously slower ( from the perspective of the traveler ) & faster ( from the perspective of they got from point A to point B faster than light within this space could have done ) becomes doable.

So, it’d be required to 1. know the underlying-structure of the universe, 2. be able to engage a “rotation” from our 3D-space to another one, intentionally, & make it be one that is travel-useful ( that may not be possible ), & then 3. do that rotation, move within that other space, & then “rotate” back into our space, at a drastically-different location.

All that’d be required is for the “rotation” to remove our having inertia/mass within this 3D-space for it to be useful, but more-complete “rotation” may be required for accomplishing real interstellar travel.

---

IF you go look for Susskind’s “Time as a Fractal Flow” video, on yt, watch it to the end, as the lightbulb goes on at the end, mentally…

but consider the implications of that:

IF time is fractal, THEN space must also be, since they’re part of the same 4D thing.

NOBODY in physics is dealing with it that way, ttbomk.

& if space is fractal, then it simultaneously is, & isn’t, there, & that may be usable.

( it’s there from within it, but it can be not-there from the perspective of other 3D-spaces which simply don’t “see” it: because each is only fractionally-dimensional, they can all be crammed into some kind of superspace, without colliding with each-other )

---

Anyways, this is just how the shape of it feels, & as I figure-out more, this understanding gets revised, but that’s the fundamental sense of it.

There are … thousands? of 3D-spaces in this universe, & we’re in 1 of them.

Electromagnetism is limited to within a 3D-space, but gravity isn’t: it diffuses throughout them all.

“Dark Matter” is just conventional matter in other 3D-spaces which are … how to say that … “coincident” with our 3D-space, but the falsifying-quotes are important: their 3D-space & ours are not-colliding, they are each fractional-dimension/fractals.

So, we’ve got “Dark Matter” galaxies simply because there isn’t any matter in OUR 3D-space, but in other 3D-spaces which are coinciding with ours, without colliding, there ARE actual-matter galaxies, & their gravity is present, weakly, in our 3D-space ( I’m presuming that gravity is weaker between-3D-spaces, that may not be true, or if it is true, it may be … anywhere from slightly-weaker to orders-of-magnitude weaker )

We’ve got a couple diffuse galaxies with NO “Dark Matter”, simply because there’s matter in OUR 3D-space, but not in the other, underlying-us 3D-spaces…

etc.

It also affects the smoothness of the Cosmic Microwave Background, too: instead of requiring that space inflated at zillions-of-times-the-speed-of-light, you can instead have thousands, or zillions, of dimensions expanding, all of the 3D-spaces expanding, but none of them going translight…

& you get the same degree of smoothness, because it’s happening in more dimensions, simultaneously, instead of happening in only 1x 3D-space, at translight speed…

---

The fact that gravity is nonlinear & QM is linear ( another of Curt Jaimungal’s videos, some utterly-hyper balding scrawney guy explaining this ), so if you put mass somewhere, the mass’s gravitational-field ITSELF has gravity/gravitational-field: it’s self-amplifying, whereas all quantum-mechanics stuff is linear… proves that the 2 theories are fundamentally incompatible: they’re different KINDS of mechanics.

I’m saying that all the QM stuff is within-a-3D-space, & that gravity isn’t within-a-single-3D-space: it’s affecting ALL of them, simultaneously.

& that we need to discover the underlying-structure which gets both perspectives into the correct relationship.

_ /\ _

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!

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

Nope

I wouldn’t even put money on interstellar travel.

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.

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

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’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.