[andy_ppp]

Probably more likely that we work out how to fold spacetime than we get there in anything like a high enough percentage of the speed of light - the fastest object we ever made travelled at something like ~0.064% * C so we are looking at ~750 years with current technology and presumably we'd need to switch on the probe in 3/4 of a millennium and figure out how to slow it down and get it into some sort of orbit around the planet.

750 years is hard for me to get excited about even as a vampire.

[fellowmartian]

It’s highly unlikely we’re ever getting FTL. We should become comfortable with that and let go our fantasies. Let theoretical physicists chug away at this, we should get underway with projects that are possible with known science.

[somenameforme]

Depends on who you mean as "we". The speed of light isn't a speed limit. If you can create a ship that is capable of 1g acceleration, it doesn't just stop accelerating as it reaches the speed of light relative to some stationary object, like Earth. Instead you start getting relativistic effects and things start getting very weird with time and distance doing some funky stuff. You keep zooming along just fine from your perspective, but an at-rest observer on Earth would see your ship asymptotically approach the speed of light, but never exceed it. The universe is very weird. In any case you could viably travel billions of light years in a single human lifetime, but for an observer at rest billions of their years would genuinely pass. In other words, traveling into the future is very much a real thing, so far as our current understanding of the universe goes.

The search term on this is 'relativistic starship.' Here's [1] a calculator to see what the math works out to for a ship capable of accelerating at 1g indefinitely. So for instance you could travel to Andromeda, some 2 million light years away, in about 28 years. But 2 million years would really pass for those at relative rest, such as those on Earth. So if you came back, the humanity you found (if any) would be unimaginably different.

And this isn't some just some weird fringe theoretical/mathematical thing. For instance GPS satellites have to compensate for time dilation because relativistic effects would otherwise have a substantial effect. Another example is at things like the large hadron collider. As a convenient effect of relativistic effects, emergent unstable particles exist far longer than they 'normally' would before decaying due to the fact they're moving at relativistic rates.

[1] - http://www.convertalot.com/relativistic_star_ship_calculator...

[ianburrell]

Relativistic starships are impossible because they require impossible amounts of fuel. "If you can create a ship that is capable of 1g acceleration" is doing a lot of heavy lifting. The rocket equation means you need to take along exponentially increasing amounts of fuel

Even antimatter rockets top out at 50% of light speed. Laser boost like with Dyson Swarm could get similar speeds because time dilation slows down the acceleration.

[jimbokun]

50% of light speed would be fucking awesome.

[lossolo]

> If you can create a ship that is capable of 1g acceleration, it doesn't just stop accelerating as it reaches the speed of light

For any object with nonzero rest mass, reaching exactly the speed of light in vacuum would require infinite energy.

[somenameforme]

This is incorrect. This is what an at-rest observer would perceive happening. What happens on the ship itself is very different.

[fellowmartian]

This isn’t gonna work, space isn’t truly empty. Even with antimatter propulsion the interstellar medium will start to vaporize your ship at speed above 0.2c.

[dempedempe]

Even if FTL is achievable (which I agree, highly unlikely), it's still extraordinarily slow on cosmic scales. The closest star is a little over 4 ly away!

And probing the universe outside the Milky Way? Forget about it.

[PaulDavisThe1st]

1. if FTL is achievable, then presumably it isn't limited to 1.00000000001 x C

2. I like to think about the size of the universe by always remembering that with the naked eye, on a good night, there's only a single object in the entire night sky that isn't in our galaxy (M3, the Andromeda Galaxy).

[jihadjihad]

I think you mean M31 instead of M3, and assuming northern hemisphere viewing only. I think the Magellanic Clouds are visible in the southern hemisphere.

[recursivecaveat]

We are still so slow and have had space travel for so little time, we are almost certainly on the "wait" side of the wait equation: https://en.wikipedia.org/wiki/The_Wait_Equation

[jimbokun]

First time I’ve seen that equation.

I love it.

[behnamoh]

The entire universe seems to be inside a giant black hole, anyway, and the more it goes, the more evidence is found to support that. Might as well find a black hole and visit other universes than explore our own.

[mr_mitm]

The next known black hole is tens of thousands of light years away. Also, the universe does not seem to be inside a black hole.

[poly2it]

What definition of black hole are you using?

[isodev]

It would help if our science wasn’t distracted by things like global warming and nazi governments though. There are definitely ways we can help the process * right now *

[parasti]

Good luck doing anything on any other planet if you can't even handle your own that's perfectly suited for your kind of life form.

[isodev]

Was it my comment you really wanted to reply to? My point is that there are things we can do right now/today in order to heal our society from the sort of malignancies that distract us from advancing as a race.

[tuwtuwtuwtuw]

Yeah, let's ignore current issues and instead focus on remote stars.

[panagathon]

Scientists and engineers with an interest in such things would have an easier time working on it, if the broader economic and civic context they work in wasn't being messed with by demagogues.

They shouldn't be drafted to resolve the rise of petty tyrants. It's a waste of their time.

[luckydata]

the message you replied to implied the exact opposite.

[wongarsu]

With variations on nuclear propulsion we could plausibly get to up to around 12% the speed of light. At least that's the number quoted for Project Daedalus [1], which is using nuclear fusion for the first stage and nuclear-powered ion engines for the second stage. With the cruder but more realistically achievable right now Project Orion design (riding the shockwaves of nuclear bombs) you could still get to ~3% the speed of light

But even at 0.12c, we are looking at 400 years to get there. And we'd be zooming by at 12% the speed of light. If we want to slow down a bit that'd add hundreds of billions to the cost.

It might be worth waiting another century to see if we can come up with a faster design in that time. Not like closer targets like Alpha Centauri, where the thing stopping us is mostly just the absurd cost

[exitb]

> But even at 0.12c, we are looking at 400 years to get there. And we'd be zooming by at 12% the speed of light. If we want to slow down a bit that'd add hundreds of billions to the cost.

That’s the really hard part. If it’s almost science fiction to accelerate to 0.12c, it’s certainly much more difficult to slow down. At that speed we’d travel and pass this small system in mere minutes.

[NoGravitas]

You just turn around halfway and use your main drive to decelerate. Yes, that does double the travel time, but it's the only way to do it. The hard part is then finding ways to get to a faster speed at turnaround time.

[wongarsu]

In most realistic settings it's even easier. For example a Project Daedalus probe only accelerates for four years before running out of fuel. So you could decelerate in just four years. Maybe a bit more, since you only have the smaller second stage engines. But essentially you are accelerating for four years, coasting for 392 years and decelerating for another four years. Accelerating for the whole time and turning around in the middle would be faster, but we don't have the fuel for that

The issue is that in the original architecture without breaking you burn 50k tonnes of fuel to get 1k tonnes of payload up to 12% lightspeed. If you want to break all the way back to zero, you need to 50k tonnes of fuel to break. But that means you need to accelerate another 50k tonnes of fuel up to speed.

Which means you need 50 times for fuel to get from 0.11c to 0.12c, and you need to accelerate that fuel to 0.11c, so you need more than 50 times the fuel for the step from 0.10c to 0.11c, and an even larger factor more to accelerate from 0.09c to 0.10c, etc. So you don't just require another 50*50k = 2M tonnes of fuel, but an exponentially larger amount. The tyranny of the rocket equation

[andy_ppp]

There is no drive, it’s all orbital slingshots with current technology. None of the other stuff people are talking about here exists…

[fc417fc802]

Just aim for the desired exoplanet and pack a really beefy shielding system. It would make for a spectacular show.

[ghm2199]

I think the only way political will can fund nasa to realize these 1960 design ideas is an infinite capacity arch rival that threatens/render irrelavent either the dollar's supremacy or american power (and just those two, because apparently these days there is no "threat"/need to defend a higher cause, like the neo-liberal rules based system or democratic or human right values). Also that arch-rival that is probably/likely not china(practically speaking)

[myrmidon]

Adding to this:

Those 190km/s of the Parker solar probe were, crucially, periapsis speed.

This is a bit like bouncing a rubber ball from a building, measuring its speed at ground level and then going: "Given our fastest achieved speed, we expect to hit the cloud level in <10s".

~200km/s sustained speed is already insanely optimistic for anything we could realistically build in the next half century, so your position is even more ironclad than it looks at first glance.

[forinti]

Universe #23: keep solar systems far enough that they can't make war on each other.

[Archelaos]

We are looking at 75,000 years. You forgot the %.

[buildbot]

Honestly a near millennia long expedition would be very cool, and doesn’t seem too long on the scale of space stuff.

[detritus]

Perhaps, but it is horrifically long in terms of human stuff.

[andrewflnr]

Yep. We haven't really figured out how to do a good government that lasts more than 200 years. Maybe unless you think monarchy is good, in which case I still don't want to share a spaceship with you.

[dingaling]

Tynwald, the Isle of Man's parliament, has operated continuously for over 1000 years

[notahacker]

The Tynwald evolved from a jury into a legislature, didn't admit its first elected member until 1866, its first few hundred years of existence are assumed rather than documented, and actual power resided with a mixture of kings (most of whom were also kings of other places or answered to kings in other places) for most of its existence. So not an ideal example :)

[cadamsdotcom]

How's their space program coming along ;p pretty spacious place, ach!

[andrewflnr]

How much of that time did it spend fully sovereign over its territory? I'd love to learn otherwise, but my impression is that it has mostly been under the shadow of England, and the pressures of a government under those circumstances are not comparable to those for, frankly, one that's more responsible for its destiny as a starship crew would be. I bet you can find lots of long-running tiny local governments with very little power, both dominated and protected by a string of larger, more powerful, but more volatile governments.

[detritus]

I have no doubt that even the most republican of cultures launched from Earth would end up thoroughly monarchistic by the time the generation ships arrived at their destination. At best monarchistic - who knows what savage new forms of society could evolve in that sort of context?

[oceanplexian]

There is a lot of precedent for this. Even on Earth, in 2026, international maritime law states that there is no such thing as a vessel with "democracy" and that a captain always has supreme command. Ships, airplanes, etc are all in a category that operate as strict autocracies.

[detritus]

Sure.

How long's the longest voyage these days?

Mutinies aren't so common nowadays, but they were when ocean voyages were measured in months and years.

[andrewflnr]

More optimistically, you might see some kind of "choosing a chief by consensus" type of situations that you see in some small hunter-gatherer societies (being careful with the word "savage", which is... usually misleading). It'll depend a lot on the size of the crew.

[dopidopHN2]

Plenty of countries are currenyly a 1000 year old.

[oceanplexian]

> Perhaps, but it is horrifically long in terms of human stuff.

Not really, unless you're obsessed with the idea that great works need to happen within your lifetime. Europe is chock full of cathedrals that took 400-600 years to build, worked on by countless generations who would never live to see them completed.

[detritus]

The difference there being that at the end of your day, having spent it masoning, you could leave the cathedral and go back to your family and have a walk in the fields and drink and be merry with people loved and new. The project wasn't the entiriety of your existence, it was merely the means to pay for it.

Unless we have generational ships the size of small countries, I'm not sure the human brain - unaided and non-forcedly evolved to do so - would be able to handle essential incarceration in a series of metal tubes for its own and its descendents existences.

[allannienhuis]

Generational ships would of course need to be very large, but I doubt it would need to be as large as you think. And it doesn't need to look like metal tubes. Many northern cities have extensive underground or between-building pedestrian bridges and large shopping malls, etc that can provide quite a lot of variety and the feeling of open and green spaces that is pretty attractive during long cold winters. Whether that's 'enough' to avoid mental health issues in a permanent setting is of course a different story, but that's just one of thousands of problems that would need to be solved before that ever comes close to reality :)

[detritus]

Yeah, this is the problem though - ironically highlighted by my still-maintained love and hope for Starship: Beyond Earth orbit, the energy requirement to move even small tens of tons of useful life-sustaining mass is incredibly expensive.

Like, to get a useful amount of people to Mars would be... the wealth of a first world nation for tens of years. Even using nuclear engines.

A generational megaship travelling at some small percentage of c to a nearby useful star (not even the nearest ones, which are all a bit shit)?

There's just nothing within our current projected reality that could even begin to accomodate that possibility.

Never mind the fact you'd need redunancy, and at least a few hundred years of testing to ensure that whatever mega project you could ultimately send wouldn't simply get vaporised halfway through, from realities unknown.

[forgotaccount3]

Knowing the variety of lives lived on earth as we speak, I'm fairly certain the first space born generation would adapt to it.

Provided the Earthlings that were sent along don't let their incarceration induced insanity infect the youngin's.

[detritus]

Maybe I'm over-thinking things. It seems like a lot of people's existences essentially revolve around a pocket-sized glowing rectangle.

Future AI and a database of all of humanity's experience before launch might be enough to keep the generational populace amused and distracted for the entiriety of their meagre, trapped existence... .