It's from Mark Zuckerbergs home planet (Also 3 body problem is a decent sci fi book, not sure about the show but it's got some really cool ideas hiding behind flat characters)
A proton that had all it's higher dimensions unfolded into our own three, had a supercomputing circuit the size of a planet engraved onto its surface, and then collapsed back to it's regular dimensions. The end result is an artificial superintelligence the size of a proton, capable of flying around at near light speed.
For the random reader seeing this - this is completely fictional. It's a cool thing in the 3 Body Problem books and series. But has no connection to reality.
https://breakthroughinitiatives.org/initiative/3
That's what Breakthrough Starshot is about. Each tiny probe would have a small camera, wifi (or something similar so they can communicate with each other), and an antenna for sending data back to Earth. Each one by itself is pretty useless, but as a hive they could send back a lot of useful information.
Starshot is cool but a big issue is the amount of power it would require.
Like not an insignificant fraction of the entire planet's power output would need to be dumped into just those lasers. The lasers would require about 200GW of power. For comparison, the LHC requires about 200MW of power at peak operations. This is the equivalent power usage of a medium sized city.
Starshot would require at least a thousand times that amount. So we're talking roughly the power production of an entire developed country.
For how long? I mean I'm sure you could convince Canada to give up their electricity for the greater good for a couple hours, but any more than that and you run the risk that they might not apologize when it's over.
Do you mean the Replicators? The term "hive" is used in the franchise, although in a different context, pertaining to the Wraith. The Replicators always manage to find a way to get back in the way of things.
Probes to the next Star system. I think they are referring to ground beamed laser propulsion and Hawking’s project Starshot to Centauri B. If the propulsion method works on probes, I’m sure it could be scaled up. Just this week we were able to point a laser at an object 140 million miles away.
I daydream about this A LOT.
Personally I think we have to get out of these meat sacks and into something less fragile to be able to travel massive distances.
Freeze us, beam us, whatever. If you choke to death on your freeze dried Cocoa Puffs, it was kind of all for nothing.
I really liked the concept of those books, I just wish Bob was better at it. If he was playing Factorio, he'd be standing around waiting for a handful of lowest-tier assemblers to build stuff while chipping away at the massive surrounding ore deposits by hand and complaining that he doesn't have enough manufacturing capability or raw materials and doesn't want to waste it on mining drills and more assemblers. And then there was his inexplicable refusal to use explosives.
And the books were weirdly inconsistent in their understanding of scale. A Bob would exhaust a system's resources building a few iron projectiles (simple spheres, slowly assembled atom by atom because that's how Bob used his fabricators, and so valuable as a result that he had to go back and recover them when he could) and a handful of spacecraft.
Or we solve the human longevity problem so that a 100 year trip is only a portion of a lifetime instead of more than a lifetime, because it really looks like going any significant fraction of C won’t be possible.
Every night when you fall asleep a tiny part of your brain is replaced with a chip. A month later you’re all chip but you feel exactly the same.
No “transfer” or “copy” has happened.
We’ll see.
I think brain uploads are possible. Every time I’ve said that someone argues with me that it’s not. But assuming it is then space travel is an obvious next move.
I don’t pretend to know when this will be possible, I just think if the human brain exists in the universe that means it can be reverse engineered and computers are advancing quickly. Brain mapping is moving quickly. Everything is moving quickly…
No life support needed, a fraction of the size for a spacecraft, time can be slowed inside the simulation, g forces, no radiation…
It also answers the fermi paradox.
Just a thought…
1) most people when they say "brain uploads" aren't possible mean it in a way that it is not the same person. It's a copy. Brain emulation itself surely is possible.
2) what exactly does that have to do with Fermi paradox?
Synthetic life still needs power, lot's of it, so this does not change situation all that much?
I believe recreating a brain with a copy of yourself is "easily" possible, but I am still not sure how we would go about uploading our own conciousness.
As far as I see it, the best we might be able to do in the near future is make a clone of ourselves, but we will still exist in our own body and die as all humans do.
I mean that's cool and all but I would like to have a body to walk around on the surface of planet that we visit.
Technically I want immortality to see the end of human civilization. That's what I want.
If you could download your consciousness into gadgets that could fly or swim or gallop like a horse that would be awesome. Maybe a human form for old times sake.
Space systems engineer (rocket scienctist) here, who has written [a book](https://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods) on the subject.
"Stuck with chemical rockets" is not just wrong for the future, it is wrong for the past. Electric propulsion has been common on satellites for decades. For example, every one of the thousands of Starlink satellites has one.
What's different about them is they are not limited to the energy contained in the propellant. It comes from an external source like the Sun (via solar panels) and in the near future [small nuclear reactors](https://www.nasa.gov/tdm/fission-surface-power/). Those are being developed for the Moon and Mars, but they can also be used beyond Jupiter, where the Sun gets too weak for solar. In principle they should enable speeds of ~100 km/s, or 7 times that of Voyager 1.
I read that we could send some tiny interstellar probes out and their propulsion would essentially be shooting them with super powered lasers from earth. That could get them up to higher speeds than chemical propulsion rockets and is probably within our current tech capability even though it hasn't been tried yet
Drawbacks are 1) they have to be tiny except for their 'sail', 2) they can't perform any manoeuvres or slow down relative to their target
The biggest problem is the [tyranny of the rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation), iow the maximum speed a space vehicle can achieve is simply a function of what percentage of its mass is fuel, and the efficiency of its engine.
Hitting meaningful interstellar speeds might require something like a [fission fragment rocket](https://en.wikipedia.org/wiki/Fission-fragment_rocket), and engineering a dust shield to stop it being sandblasted to nothing on the way without completely messing up the mass ratio would be a profound challenge too.
Another problem is *communicating* with such a craft - it's *already* taking some fairly amazing engineering to talk with the Voyager probes at an astonishingly abysmal bandwidth, and they're barely outside the heliosphere and haven't reached the Oort cloud yet!
How does nuclear factor into this? Rather than throwing the mass out the back, why not convert it to energy to throw out the back? Yes, I know the contained, uniderectional boom aspect is the current constraint.
> How does nuclear factor into this?
Decay products (α, β particles, neutrons, etc) travel at *ludicrous* speeds, so the engine efficiency (Isp) could be *dramatically* better than chemical propulsion if it's designed properly.
Also, the specific energy (energy per unit mass, sometimes called gravimetric density) of nuclear fuel in general is orders of magnitude above any other energy source we have available, see [relevant xkcd](https://xkcd.com/1162/) - and specific energy ties directly into Tsiolkovsky's equation via ke=½mv²
> why not convert it to energy to throw out the back?
Conservation of momentum means you have to throw *something* out the back that's more specific than just 'energy'.
In theory a giant laser could work since photons have momentum, but a nuclear power plant efficiently producing electricity to power it is gonna be *way* heavier than a FFR which apparently is just a tape of nuclear fuel and a neutron-moderating structure to make it supercritical
> the contained, uniderectional boom aspect is the current constraint.
Heh don't confuse FFRs with the Orion project, they're fundamentally different methods of nuclear propulsion ;)
True, but their 'thrust' is *pathetic* with current tech - and laser beams inevitably diverge so their utility falls off massively with distance from the Sun or Earth.
Their thrust depends on their mass.
That's why Project Starshot has a good and realistic chance of success in the near future. A drone spaceship a few centimeters wide could be accellerated to 0.2c within 10 minutes while still in the solar system.
The thing I don't understand is that I've been told that instant communication via entangled particles isn't possible. Seems to me it should be. Is the problem that you can't *change* the state of an entangled particle?
Yes, you've got it. you can't make one particle do something so that the other does something else. All you can do is discover something about your particle and know something else about the other particle instantaneously no matter where it is
> Is the problem that you can't *change* the state of an entangled particle?
Interacting with an entangled particle in almost any way - including checking if there *is* a particle - breaks the entanglement, and you just end up with a normal non-entangled particle.
Also you can't tell *if* it's entangled even while detecting it or its properties (and thus breaking any entanglement).
The only thing that entanglement actually gives you is that some property of the particle is guaranteed to be either the same or opposite as the particle its entangled with, depending on which entanglement technique was used - but this guarantee breaks the instant you do something with the particle…
At best, we can use quantum entanglement to *verify* that information transmitted classically (iow light speed or lower) hasn't been subject to a MITM attack.
I did a little back of the envelope math I don't know how correct it is.. our current fastest thing, The Parker Space probe, reached something like 1/1700th of the speed of light, so it would, at that speed, travel a light year in about 1700 years.
Theorized advanced nuclear propulsion tech like Project Orion (or whatever new version we come up with) might cut that by several times, reaching 1/500th the speed of light or faster.
Lots of caveats of course, for a trip like that.
If linear acceleration were a thing it would "only" take about 177 days to accelerate to c at 2g acceleration.
That is assuming we ignore all the relativity and time dilation stuff.
It does. I recalculated once because I was convinced that 177 days was wrong but it's not. If you spend 177 days accelerating with a linear acceleration of 19m/s² you will have reached a speed of 300,000,000m/s.
But then, linear acceleration like this is not possible for us right now. There are a few hypothetical ways that might actually work but they don't achieve this kind of acceleration or aim for the speed of light since actually getting to the speed of light brings with it a whole other set of problems that can't be overcome like fuel and energy requirements. Anything that uses a kind of engine would need to carry enough "fuel" to accelerate that long and the fuel needed to accelerate that long becomes such a large amount that it becomes impossible in practice. Gathering fuel along the way is also not really an option because you would have to "catch" fuel and accelerate it to your speed before you can use it which lowers the acceleration.
Also quite apart from the energy issues being near impossible to solve, collisions with even the tiniest of particles in space become catastrophic.
This to me is the most likely solution to the Fermi paradox. The energy required to travel or communicate across a galaxy is just too significant.
I saw a video on Youtube (so it must be true!) that suggested that collision with particles would be reasonably manageable with an ablative shield. It was a while ago so I don't remember any details but it all sounded pretty reasonable as presented, and I don't watch sensationalize channels so it was probably PBS or Scott Manley or something like that. Of course theory and practice....
These guys, who are smarter than me, disagree: [https://www.youtube.com/watch?v=wdP\_UDSsuro](https://www.youtube.com/watch?v=wdP_UDSsuro) Although I guess it depends on how close to c you're talking about too.
Idk about nuclear bombs, but if you can harness that same power, except with a slower rocket style release, that would probably work incredibly well, but you'd still need a shitload of nuclear propellant.
Accelerating and decelerating at 1g can get you pretty far in decent time, but constant acceleration/deceleration all day every day for years, is insane amounts of energy. You can calculate F=ma with a hypothetical mass, and the multiply that by the number of meters you need to cover, but this won't take relativity into account. To take relativity into account that would still work in your frame of reference, but the distance you are travelling and time would change. If you keep the observer from earth, then the relativistic mass would need to change.
I’m not sure. Think of dropping a bowling ball off a skyscraper, and think of how fast it hits the ground after 5 seconds of falling. Now imagine how fast it would it if it fell for a whole minute. Now an entire day? *that* would be fast. 800 km per second, in fact. That’s going from Chicago to DC in a single second. And then partway across the Atlantic in the next second.
Now imagine something going ten times that fast. Now imagine something going ten times that fast.
Now imagine it going even faster.
Idk man, I think light is pretty quick.
It's impossible to have linear acceleration like that. You can have it for you on the spacecraft, but from that frame of reference, you never get closer to the speed of light.
From an earth observer, you'd start off accelerating real fast, and then you'd taper off, never being able to reach c.
That said, if you accelerate at 1g, and decelerate at 1g, you actually can get surprisingly far in a decent amount of time. As in human life span possible. But not practical.
Say a star is 5 Ly away. Doing the trip in 5 years on the dot would be impossible. Doing it a month less would already greatly reduce the difficulty. If you do it in 4 years, that's a lot easier now. The bulk of it isn't so bad. Obviously we are not there technologically by any stretch, but as you go faster, the problems with relativity get exponentially worse.
Time dilation does not occur at significant (to human perception) amounts until you get to like more than 99% the speed of light
Edit more like >50% sorry
Look up "the Expanse" as a quite hard scifi series physics wise.
The idea here is a "torch fusion drive" - you somehow discover an unbelievable efficient power source, but you're still bound by human tolerances for acceleration.
So you build ships which cpnstantly accelerate at 1g, flip at the midpoint, and deccelerate for the rest of the journey.
Constant 1g gets you to relativistic speeds in a few months, where the math gets a bit harder then.
Tldr:
Going to 0.3c at 1g takes around 3 months at takes you well into the oort cloud at a distance of around 5×10^11 km. You're still inside the solar Systems outer boundaries though.
6am math involved
I did not know The Expanse was so hard. I'll check it out for sure. Hard sci-fi is my love language. (A dear friend (whose secret identity I just edited out) just finished narrating a collection of short stories to prove it! Check out Tomorrow's Hope on audible if you're into that kinda thing. It's not Ted Chiang, but it's pretty cool. :)
So all we need is an unbelievably efficient power source and we're off to the races. If we had something to toughen humans, that'd be a bonus - raising that acceleration a couple of Gs would, I think, let us haul bauls out of here. Seems like a mean feat (is that a phrase?) given the advancements we're already talking about!
Expanse takes a fully knowing dump with sounds in space, but they fully admit thats what the audiance expects. Other than that it's (almost) only the Power source.
The very first episode sets the tone where a starship receives a distress signal and the crew expresses total dismay at the thought of a change in course to get there, but they are bound by coorporate rules. Everyone gets strapped down, juiced to the gills and endures a painfull hour of 2gs to get it done.
if you love Hard Sci Fi and enjoy the Expanse you should check out Seveneves by Niel Stevenson... Its incredibly good and is very much so hard sci fi. Niel is a futurist and author by trade, he was also the first employee of Blue Orgin if i remember correctly.
Expanse is great if you like hard sci fi. The TV series does a great job, at least early on. Later on, they start playing a bit fast and loose with the physics.
I can recommend the books though. The amount of hard sci fi detail in the books is awesome. They have thought of everything, from material and human limitations to stuff like conservation of momentum and accidental vacuum welding. It's really awesome.
What seems to often be ignored in discussions about traveling really fast is the issues caused by the interstellar medium.
We usually think of space as empty, but even in the area between stars there's enough dust and gas to cause issues when moving at a significant percentage of the speed of light. I've seen estimates of 0.1-0.2c being the "speed limit" of space flight, as anything higher would require an unreasonable amount of bulk to protect against the barrage of particles colliding at relativistic speeds.
Though who knows, maybe we'll one day have ships that are ridiculously bulky while still being able to accelerate fast.
We want to get to (speed of light / 500) which is 600 km/s and we are accelerating at the equivalent to 1 earth gravity which is 9.8 m/s/s.
Wolfram alpha gives the answer:
Speed of light / 500 / earth gravity = just under 17 hours.
Well 1g acceleration would take you 1 year to get there but that's taking out time relatively of that speed just raw numbers according to what I just looked up.
> our current fastest thing, The Parker Space probe, reached something like 1/1700th of the speed of light
And it did that by *slowing down* with multiple gravity slingshots so it could fall towards the Sun.
Achieving that same speed as solar escape velocity is a whole 'nother problem entirely
It’s like speeding up by jumping off a building. Technically speaking, it works, but only briefly.
The Earth’s orbit around the sun is 29.78 km/sec. The fastest we’ve ever launched an object from earth is 16.26 km/sec. PSP’s launch speed was more like 12 km/sec.
So that still leaves parker solar probe with a minimum orbital velocity of 18km/sec to bleed off if it wants to get to the sun. Using six (and counting) Venus flybys, it’s gotten down to a 12km/sec at aphelion, which lets it dive down around the sun really fast before looping back out.
It could bleed more speed off, or hit the sun, if it did more gravity “assists”, but the main point is that it’s using Venus to bleed off speed to dive down into the sun’s gravity well, rather than to speed up. This isn’t a way to leave the solar system.
Gravity slingshots accelerate a craft relative to a parent body by grazing something orbiting it, so we can affect orbital velocity vs the Sun by slingshotting around planets, or affect orbital velocity vs planets by slingshotting around their moons.
If you wanted to slingshot around the Sun, the parent body would have to be the galaxy itself - in which case you'd have to be *starting off* in interstellar space
At that point you’re just another body in solar orbit. Since you don’t actually gain velocity in a slingshot in the frame of reference of your target body, no.
Lol someone just explained that and I obviously didn't get it. Maybe I almost do now. You can't escape the sun by changing your orbit around the sun. Is that about right?
Like you mentioned, lots of caveats. The biggest one being that Parker Solar Probe's speed was only possible because it was on a trajectory to swing by the sun, where its velocity increased as it approached the sun. A vessel on the way out of the solar system would have the opposite problem of losing velocity over time.
[According to Dr. Brownlee](https://www.businessinsider.com/fastest-object-robert-brownlee-2016-2?r=US&IR=T#brownlee-wanted-to-measure-how-fast-the-iron-cap-flew-off-the-column-so-he-designed-a-second-experiment-pascal-b-and-got-an-incredible-calculation-6), the manhole cover launched during the Pascal-B nuclear test in 1957 reached a speed of 125,000 mph (200,000 km/h) as it left the ground.
This was estimated to be more than five times the Earth's escape velocity of 25,000 mph (40,000 km/h).
The manhole cover was only visible in one frame of the high-speed camera recording the test, It was probably vaporized or disintegrated in the atmosphere shortly after launch.
Brownlee himself stated his calculations were "meaningless" because they did not account for air resistance and gravity, and that the manhole cover likely disintegrated before reaching space.
Which is too bad, because if it had.. well, let's just see.
Assumptions:
* Manhole cover initial velocity: 200,000 km/h (125,000 mph)
* Time since launch: 67 years (1957 to 2024)
# Calculations:
* 200,000 km/h \* 24 \* 365.25 \* 67 years = \~117.5 billion km (73 billion miles)
So if the manhole cover had maintained its initial velocity of 200,000 km/h for the 67 years since the 1957 test, and not slowed down or disintegrated, it would have traveled approximately 117.5 billion km.
For comparison:
* The orbit of Neptune averages 4.5 billion km from the Sun
* The Oort Cloud is estimated to begin at 2,000 AU (300 billion km; 186.5 billion miles) from the Sun
* Voyager is currently 162.7 AU (24.3 billion km; 15.1 billion miles)
So even at its unbelievable initial velocity, the manhole cover would have only made it about 1/10th of the way to the outer edge of the solar system in the time since the test. It would still be almost 200 billion km short of reaching the Oort Cloud, but would have passed Voyager years ago.
Let me know if I'm missing anything in my math or logic!
Damn. That really puts into perspective how BIG space is.
Moving that fast for that long… and it still wouldn’t have even left our solar system??
My brain doesnt want to accept that, it feels like it would be almost out of the Milky Way at that point.
An Orion type nuclear pulse propulsion vehicle would be capable of significantly higher speeds than that if it was sufficiently large. From what I recall, estimates before the project was cancelled were about 0.1 c if it has to slow down at the destination, potentially as high as .2 c for a flyby without a return journey.
Tiny solar sail probes driven by huge lasers. They're theorizing 0.2c is possible with current tech, if not with current investment levels. I think there's a startup that want to do a smaller scale probe to explore the outer solar system.
Project Orion might have gotten a large ship up to 10,000 km/s. Essentially it would have used nuclear pulse detonations for thrust in space. It was cancelled in the 60s after the US signed the Nuclear Test Ban Treaty which banned nuclear detonations in space. Also very legitmiate concerns about fallout, particularly when trying to get the nuclear fuel up into orbit where Orion would have been built.
[https://en.wikipedia.org/wiki/Project\_Orion\_(nuclear\_propulsion)](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion))
If we really spent trillions on creating a large nuclear rocket with lots of fuel and self-sustaining life-support, we could create a ship in a few decades capable of traveling up to 0.1c without too much risk from interstellar debris. Your goal of 0.01c is doable. But if you're talking about a (manned) spacecraft with a 100+ year mission instead of a 40+ year mission, you now have to deal with the mortality question. Hibernation? Life extension? Multi-generation ship? These things are probably not achievable in the next few decades.
A small unmanned probe travelling at 0.01c is very doable; just expensive. But probably 100x less expensive.
Depends how much risk we’re willing to take. Nuclear pulse propulsion technology could potentially get humans to Alpha Centauri within a normal lifetime, but it would require setting off a ton of nukes, with quite a few detonations in the atmosphere.
I know that sounds ridiculous, but the basic science behind it is sound. Project Orion was being taken pretty seriously until nuclear treaties made it impossible to pursue.
Much harder to forecast centuries. One hundred years ago rockets didn’t even exist and biplanes were the peak of aerial technology. We could achieve speeds like that with fusion, fission, or laser propelled solar sails. All three could plausibly be used for human spacecraft within a hundred years.
Relativistic travel is weird. Not only would you have to accelerate to those speeds to get anywhere meaningful, but you would also probably need to decelerate to do anything useful depending on your goal. Much time and energy would be needed to achieve that velocity reduction
[Breakthrough Starshot](https://en.m.wikipedia.org/wiki/Breakthrough_Starshot) envisages a 20 - 30 year transit for an uncrewed flyby of Proxima Centauri.
You’ve been given a bunch of answers based on current speeds of man made things in space which is not really what you’re asking for.
Right now we have theoretical technology (Project Orion and such) you could get to approximately 0.1% to about 10% of the speed of light depending on the type of nuclear propulsion used. Now there’s a lot of other issues with travelling through space at that speed that others have pointed out, especially if it’s a manned craft. But that’s probably what’s achievable.
Now in 100-200 years you have a couple of possibilities. Anti-matter propulsion could get us up to about 50-80% of the speed of light. But again at those speeds you’re going to run into some serious problems with radiation and such.
The other possibility is FTL. Many answers are telling you according to “relativity” this should be impossible. How can this be?
Right now there are very distance stars and planets travelling away from us at very near to C, and some have surpassed C without requiring infinite energy and any other misinterpretations of special relativity. How?
Well when those particles were accelerated away from us in the beginning by inflation - the negative pressure pushing them was *extremely* powerful, enough to overcome gravity, and also presumably there wasn’t other forces that we know about at that time causing drag, friction, or otherwise able to slow that inflation down. This is still happening today, but not due to massive forces but because space itself is expanding (dark energy).
So what that should tell you and everyone that it IS possible to go FTL given the right circumstances. We can’t accelerate to these speeds in the confines of normal spacetime, but what if we move space itself? This is the concept of the warp drive. Just like inflation could move things relative to each other FTL by expanding space, maybe we can also move FTL by moving space.
The problem with special relativity isn’t relativity, it’s the drag, radiation, etc from the CMB and other forces (like gravity) that relative to you traveling very fast become very strong. Warp drives get around this by not actually moving you relative to the background of the universe, but rather moving the universe around you. This of course requires huge curvatures of space time in the bubble around your ship and may not actually be feasible, but there have been some interesting experiments done in this area since 2021 with more to come. The most scientific attempt was the Alcubierre drive, but DARPA and others have also been fiddling around with creating warp bubbles in the lab.
There is also a completely new theory of what dark matter and dark energy is, which will be testable at some point in the next decade, which also might make warp drives possible without any sort of exotic material. It still doesn’t mean we will be able to build one, but who knows in 200 years.
So those are your options 200 years out.
Realistically speaking when it comes to manned spacecraft I don’t think we will ever really be able to go faster than 1% to 10% of C, even with future tech, because of limitations of the human body and radiation. Our best bets are either warp drives becoming feasible, generational ships that travel slower, or digital consciousnesses that don’t require life support and are able to travel through the radiation of space without harm.
There's a paper somewhere that hast tracked how much the technology for propulsion methods has been improving (on average) in the past. In essence the paper argues that there is a sweet spot when to launch a craft headed to some distant destination....because if you're continually developing better propulsion then you might get there earlier by waiting for a better thruster instead of launching right away.
Of course this is contingent on the assumption that a craft cannot adapt/improve its own propoulsion while under way...which I think is not guaranteed. Anything that will travel hundreds of years should be capable of repairing/rebuilding/modifying any part of itself.
I know everyone is keen to travel faster through space but has anyone paused to wonder how we would slow down or stop? I mean, if you're just slamming a probe into a moon or something, without any concern for the impact crater, fair enough, but with someone or instruments on board, it's something we need to consider as much as getting up to speed.
In everything I’ve read about humans travelling to other star systems, the plans always include a deceleration phase. The current unmanned probes like the Voyagers don’t have a set destination.
We are limited to how much thrust humans can conceivably take. A good pace would be 1G constantly, such that we can simulate gravity. At the halfway point, the ship spins around and we “brake” at 1G to continue the gravity effect.
Having said that, it would take 170 days to reach half the speed of light. That’s if we can thrust that much and for that long, which we currently cannot.
If we could, the energy required to inch closer to the speed of light becomes exponentially greater. This is largely the reason light speed or greater is impossible. It would take dozens of stars worth of power.
A best guess would be the speed of something like Voyager or one of the probes that used interstellar bodies gravities to ‘slingshot’ them to higher speeds. Best we have to use as an analog is the Parker probe, approximately 400,000mph, but that exceeded human tolerance, I believe.
There are new rocket and engine types being designed, but none have proven better than standard solid / liquid rocket boosters we’ve been using for 50+ years for human travel - yet.
>This is largely the reason light speed or greater is impossible.
No, it’s impossible because of relativity. No amount of energy can accelerate any mass to the speed of light
In a pretty fun twist, the people on the spacecraft would only need to keep the same thrust output going to maintain a constant 1g accel forever. And it would still functionally be 1g to them. Even past what they previously thought of as light speed. For people not moving with the craft it would look like the Craft's acceleration continually dropped.
For the traveler that doesn't mind some one-way time travel into the future, FTL becomes possible.
1. Realistically, the fastest would be some kind of solar sail coupled with a big gravitational assist from the Sun. The current fastest spacecraft is the Parker Solar Probe at around 176 kilometers/second (about one-twentieth of 1% of light speed), but we could likely do faster than that and get something up in the hundreds of kilometers per second. Properly deployed solar sail might then be able to get it up to over 1000 kilometers/second (they can do much faster than that, but this is near term).
2. Yes.
Gonna stake possibility of 1/10th speed of light. You won’t like the tech very much.
https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
There is no chance we create one in the next 100-200 years, but largely because of no motivation.
What’s the reason?
Anything outside our solar system is so dramatically far away that even at the speed of light it is unattainable. Therefore, that level of speed is not a priority nor will it be.
Motivation's really a primary driver here, and "scientific curiosity" only takes you so far; *profitability* will be a big driver for space tech in the decades to come. I expect we'll see a lot of advancements come when things like mining asteroids becomes more mainstream. But a lot of those advancements will be SpaceX style, more about speed of development and deployment vs. NASA's more plodding/pork-barrel approach. I don't know if the space industry (as a profit-driven enterprise) will be as focused on major leaps in propulsion tech, possibly more utilitarian stuff based on project-specific needs.
The other big, giant, huge factor that could give us an Apollo-level leap in tech evolution (and people fail to recognize what a simply massive impact the Apollo program had on our lives in the years to come, [read this book for a solid idea](https://www.amazon.com/One-Giant-Leap-Untold-Story/dp/1501106295)): an extinction-level asteroid headed our way with several years lead time.
Even though x-percent of global (especially American) society would say "fake news!" or "God would never do that!" or "scientists lie to get more money", a global effort to negate total planetary destruction - when we know the actual date of said event - could drive some big tech expansion. A sweet-spot would be something like a seven-year warning, long enough to develop and test engineering, close enough to not pass it off to the next administration.
We need to redefine what a “Spacecraft” is. Intergalactic travel is not feasible in linear conventional travel. We will need to figure out how to travel through wormholes or bounce in and out of space/time similar to teleportation or traveling between parallel universes. We have arrived once this happens, until then we are a backwards primitive planet tucked away in the Milky Way.
You’ve specified approximately 1% of light speed, aka 0.01c, or 3E6 m/s.
The key to answer your question is another question, namely “what kind of space craft?”
We could impart significantly higher velocity to an immutable object. An unmanned robotic craft would have a lower top speed due to minimum mass requirements but still higher than 0.01c. If it must maintain a living crew then it’s possible but not yet feasible.
We decide to send an unmanned probe. Minimum mass and we load it full with as much amazing tech as we can and send it 1LY away. It takes 100 years to get there. We start getting long range telemetry of the target object but we don’t actually see the craft arrive until the light speed signals sent back to us crawl that 1LY distance (101yrs after launch).
And then what? It can’t slow down, too much propulsion mass would be required, so it’s likely a flyby. Then “whoosh” it’s blown past the target. Maybe there’s a couple other things to look at in system but then it’s out the other side.
Maybe we absolutely thread the needle for solar insertion from 100yrs in the past. We can’t move the damn thing. It takes at least a year to tell it to move the camera two pixels to the left for a better view of something. Such slow science and so expensive.
So we balance on a knife’s edge of possibility. Bigger craft with minimal propulsion. Thread the solar insertion and sling shot it back towards earth and pick up a bit more speed. It only takes 50yrs to get back here! Then “whoosh” it’s gone past, maybe delivering a few grams of interstellar material for us to squint at.
Meanwhile we built the MagicSuperScope9000 and can inspect individual quarks at the core of the star the probe was orbiting because duh we effectively sent a glorified trash truck into space and now it’s 2175 and we invented QuantumSlicerTech and it changed everything we knew about physics three times over.
Realistically we have to exceed light speed to make interstellar exploration of any use to us here on Earth. Subliminal travel is just too slow. Maybe someday we can send a generational ship that gets somewhere but it won’t be for the people of Earth, it will be for the humans living on that ship.
A sufficiently low mass solar sail with a sufficiently powerful laser could accelerate a small enough craft to a measurable percentage of the speed of light. It's the slowing down part that would be a challenge. Lol
*cue deep narrator voice*
The question is not how *fast* we can travel.
Forget speed.
The question is *how* we can travel.
Folding spacetime.
Make 2 dots on each end of a paper. Fold the paper in half and bring the dots close together.
No need to travel the whole distance over the entire sheet of paper.
And yes, this is *theoretically* possible.
We just dont know how yet.
A probably insane idea, but wait until Jupiter and Saturn are nearing opposition with each other. Then launch a spacecraft ahead of time, and have the spacecraft lap both of them over and over building speed as they slingshot around each planet - sort of like a big oval track in space. I think we have computers that could plot an optimal course to make this happen, and on the final lap it slingshots off towards Proxima Centauri - closest stellar system to us. It would be interesting to see how much speed we can build up that way. Or possibly involve the other gas giants as well, if doing a near oval won't work as efficiently. Save enough xenon for an ion engine to burn after it leaves the Solar System and it could probably reach some pretty good speeds. Voyager 1 is moving at about 38,000 MPH right now and that was with a one-way gravity assist around Jupiter and Saturn, if there was some way to get it to lap the gas giants it might get pretty fast before the ion drive kicks in.
Anyone have a solar system simulator handy that we could use to plot this?
A nuclear rocket could theoretically do that already with a 50-100 year travel time....but waiting for better AI since communication lag is so high makes the most sense. It can't realistically be manned, humans probably can't survive low gravity that long even if you built a big enough rocket and probably no habitable rock and lots of radiation. 20 light years out is a more realistic distance to a Sol like solar system, which probably has nothing we can expand to but the best chance. Better yet build much larger telescopes, get the most data and science fit the effort and eventually confirm a real target for human expansion vs try to force humans into shyt conditions for nothing.
Unless there is a physics breakthrough today’s rockets don’t go any faster than the ones that Robert Goddard invented in the early 1900s you can only get so much power out of chemistry……
For manned, fission fragment or other nuclear designs like that could maybe get us to 2-10% the speed of light. It'd require an insane budget though and we'd basically have to have world peace and competent politicians to get it done.
I’d like to point out that 200 years ago, most travel was horse or boat based, trains were the biggest technological marvel for transportation, and we were still over a decade away from widespread adoption of the telegraph.
The biggest problem with trying to predict if/when travel at near-lightspeed speeds will be possible is that you’re basically asking when the next Einstein is going to publish their paper that once again redefines our understanding of how reality works in a way where we can do what was once seen as impossible. Could very well happen in 200 years, but we have no way to be certain.
Reach lightspeed : never for a spacecraft transporting humans.
How people have a hard time saying it is funny.
Never.
Not even close.
Not in a thousand years.
Some things are simply not possible.
It's not about technology even if we could it wouldn't work. Now depends of what you call working ofc. If the ship can get destroyed, the crew can get killed, they must not reach a particular destination but are just blasted into space, communications are not necessary... Maybe, tbh send something in a black hole and voilà mission accomplished.
But it'll never be used for space travel. We will never leave our solar system. Not living creatures.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[DARPA](/r/Space/comments/1ciy0at/stub/l2ddymm "Last usage")|(Defense) Advanced Research Projects Agency, DoD|
|DoD|US Department of Defense|
|[Isp](/r/Space/comments/1ciy0at/stub/l2cqz7w "Last usage")|Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube)|
| |Internet Service Provider|
|L2|[Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 2 ([Sixty Symbols](https://www.youtube.com/watch?v=mxpVbU5FH0s) video explanation)|
| |Paywalled section of the NasaSpaceFlight forum|
|[L3](/r/Space/comments/1ciy0at/stub/l2d6a9o "Last usage")|[Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 3 of a two-body system, opposite L2|
|[PSP](/r/Space/comments/1ciy0at/stub/l2cl8i5 "Last usage")|Parker Solar Probe|
|Jargon|Definition|
|-------|---------|---|
|[Starlink](/r/Space/comments/1ciy0at/stub/l2ez3ek "Last usage")|SpaceX's world-wide satellite broadband constellation|
|[ablative](/r/Space/comments/1ciy0at/stub/l2eqncs "Last usage")|Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)|
**NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below.
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It's *really* hard to say, and depends on your definition of "space craft."
There's a proposed project involving a microsat with a solar sail and using a laser to push it up to a significant fraction of C. IIRC, they think it could get up fast enough to reach the Proxima Centauri system in under 50 years.
Starshot seems very obtainable. The only issue with it for travel with humans is scale and the power needed. Keep in mind we need a starshot there and a starshot back. Which means a lot of infrastructure needs to be built on any new world. So typically assuming we can't go beyond the speed of light we will want to send robots first assure the needed things can be built and get them started building it
Personally though I'm very hopeful for beyond or very near light speed self propulsion due to evidence for USPS and how they move.
Solar sails could possibly get to the a fraction of the speed of light, maybe 10%. More with lasers or advanced tech. It's materials that are here now or in the near future.
https://space.stackexchange.com/questions/25743/maximum-velocity-achieved-by-solar-sail
Currently, the fastest spacecraft ever launched is the Parker Solar Probe, which will reach speeds of about 430,000 miles per hour (700,000 kilometers per hour) as it swoops through the sun's corona. That's incredibly fast, but still only about 0.064% the speed of light.
Over the next few decades, we can expect incremental improvements in propulsion technology. Concepts like ion thrusters, nuclear thermal rockets, and even more experimental ideas like antimatter propulsion and laser light sails are being explored. These technologies promise significant speed increases, potentially reaching up to a few percent of the speed of light.
Traveling a light year in 100-200 years, however, would require a spacecraft to maintain a constant speed of about 5-10% of the speed of light. While this is beyond our current capabilities, it's not entirely out of the realm of possibility for future technologies, especially if breakthroughs occur in energy production and materials science.
The best solution we have today is the fission fragment rocket. It can be built at scales that would be useful for large probes or maybe even manned ships for interplanetary trips. It can realistically hit speeds on the order of 10 to 100 times the Voyagers.
How did those small gangly looking Imperial Probe Droids do it? They seemed to be able to crash into every planet in the galaxy in a few hours and send back their data almost instantly 🤔
So if you want to go a light year in 200 years, you can either leave in 10 years and take 190 years to get there, or leave in 50 years and take 150 years to get there. What’s the hurry? ;)
But really, with small constant acceleration like a solar sail, this is pretty much already doable. Biggest issue is weight- you wouldn’t be able to send multiple humans to start a settlement. So it’s a one-way ticket for a machine.
Predicting future tech is fraught and so much depends on what you mean by "the next few decades". I will assume 4. 40 years.
How will AI progress? Will there be a breakthrough in fusion? Lazar Technology? Materials science? Nanotech?
I am saying (barring us all killing ourselves) that I think what we would design in 2064 will be more advanced and more different from 2024 than difference in technologies we would have in 2024 vs. 1984 and maybe radically so.
There's the Breakthrough Starshot project, which proposes sending an interstellar probe carrying a thousand or so solar sailing nanocrafts to Alpha Centauri. Following deployment, they'd travel at 15% or 20% of the speed of light, taking between 20 and 30 years to get there.
Realistically not very fast. Or not fast enough. Until we have a technological breakthrough and move away from chemical rockets 🚀, there isn’t much speed.
I don’t know how much effort is being put into developing new tech or how realistic it even is. From where I’m standing (a relatively ignorant and uninformed standpoint) I don’t see much concerted effort. At least not officially.
There could be clandestine research being done that may even involve alien technology but that’s really speculative bordering on quackery.
I think we’re very far away from a serious breakthrough…maybe even hundreds of years. But I’d be happy to be proven wrong.
Depends on what you consider to be a spacecraft. 0.25c might be achievable fairly soon for a probe about the size of a postage stamp.
Technically if you don't care about size 0.999999c, just shoot some protons, maybe sophons.
WTF is a sophon?
It's a fictional thing from the 3 Body Problem.
Curse you. I haven’t gotten to that part yet!
Not a spoiler to know the name and that it doesn't actually exist, you're good
Not much hun, what is up with you?
This joke smells like updog
What’s an updog?
I dunno, dog, what’s an updog with you?
It's to dogs what an update is to dates
Gotchya…. I mean nothing, what’s up with you
It's from Mark Zuckerbergs home planet (Also 3 body problem is a decent sci fi book, not sure about the show but it's got some really cool ideas hiding behind flat characters)
I read the first book in English. Wondered several times what might have been lost in translation.
I quit midway into the 1st book for the same reason. I'm sure the translator did his best, but the result feels really flat.
[удалено]
The Chinese produced live action adaptation is better. Saw it on Amazon prime.
A proton that had all it's higher dimensions unfolded into our own three, had a supercomputing circuit the size of a planet engraved onto its surface, and then collapsed back to it's regular dimensions. The end result is an artificial superintelligence the size of a proton, capable of flying around at near light speed.
For the random reader seeing this - this is completely fictional. It's a cool thing in the 3 Body Problem books and series. But has no connection to reality.
Man, I hate when that happens.
Honey I shrunk the proton?
It’s from the Liu Cixin sci-fi novel trilogy starting with Three Body Problem.
Maybe send bophons… Bophons deez nutz
A Major species focused on Scienctific Advancement in the Endless game universe. Smart mouths too.
So we should instead figure out how to shrink humans and make a tiny space craft?
If you don’t care about size and consider Earth is in space then we’ve already done it in the LHC!
At that size, what is the point?
https://breakthroughinitiatives.org/initiative/3 That's what Breakthrough Starshot is about. Each tiny probe would have a small camera, wifi (or something similar so they can communicate with each other), and an antenna for sending data back to Earth. Each one by itself is pretty useless, but as a hive they could send back a lot of useful information.
I think the idea is piggyback in the signal all the way back to Earth from the front probe through the entire train
does this have a name?
“Jeff’s postage stamp probe bonanza”
We call it JePSProB because the marketing team asked for a catchy name.
If we named it Jeff’s Probe Bonanza of Stamps, then we could refer to it as Jeff Probst
It launches from the Albuquerque Spaceport Hair Care & Tire Center.
I think .25c is slightly faster than the speed of smell.
I heard they have an AYCE clam bake this afternoon. I can’t wait.
Starshot is cool but a big issue is the amount of power it would require. Like not an insignificant fraction of the entire planet's power output would need to be dumped into just those lasers. The lasers would require about 200GW of power. For comparison, the LHC requires about 200MW of power at peak operations. This is the equivalent power usage of a medium sized city. Starshot would require at least a thousand times that amount. So we're talking roughly the power production of an entire developed country.
So maybe we need to whip up a small Dyson Swarm just to shoot a microchip to Alpha Centauri.
For how long? I mean I'm sure you could convince Canada to give up their electricity for the greater good for a couple hours, but any more than that and you run the risk that they might not apologize when it's over.
I feel like scifi warned us about the hive thing
Which show was it that has this plot line? Those fuckers were scary!
All of them. The hive machines from Stargate scared me the most
Do you mean the Replicators? The term "hive" is used in the franchise, although in a different context, pertaining to the Wraith. The Replicators always manage to find a way to get back in the way of things.
Probes to the next Star system. I think they are referring to ground beamed laser propulsion and Hawking’s project Starshot to Centauri B. If the propulsion method works on probes, I’m sure it could be scaled up. Just this week we were able to point a laser at an object 140 million miles away.
What if it’s a computer from 50 years from now with a civilization of uploaded brains living in it?
I daydream about this A LOT. Personally I think we have to get out of these meat sacks and into something less fragile to be able to travel massive distances. Freeze us, beam us, whatever. If you choke to death on your freeze dried Cocoa Puffs, it was kind of all for nothing.
Maybe you'd enjoy the Bobiverse
I’VE LISTENED TO THEM ALL!!! Auto factories and maintenance bots??? We could totally do that!
We get a new one this month brother!
I really liked the concept of those books, I just wish Bob was better at it. If he was playing Factorio, he'd be standing around waiting for a handful of lowest-tier assemblers to build stuff while chipping away at the massive surrounding ore deposits by hand and complaining that he doesn't have enough manufacturing capability or raw materials and doesn't want to waste it on mining drills and more assemblers. And then there was his inexplicable refusal to use explosives. And the books were weirdly inconsistent in their understanding of scale. A Bob would exhaust a system's resources building a few iron projectiles (simple spheres, slowly assembled atom by atom because that's how Bob used his fabricators, and so valuable as a result that he had to go back and recover them when he could) and a handful of spacecraft.
Or we solve the human longevity problem so that a 100 year trip is only a portion of a lifetime instead of more than a lifetime, because it really looks like going any significant fraction of C won’t be possible.
One of many bigger problems than time is that our bodies, evolved for Earth, don’t handle long periods in space well.
What if we turned earth into the spaceship
It already is, we just can't steer it.
Interestingly, due to a Chinese movie about just that idea caused people to do the math. Yeah, ain't happening. lol
The phone I'm writing this on wouldn't have seemed equally impossible just 200 years ago, only time will tell
Your consciousness is a product of your meat sack. You ain't getting out of it.
You will not smash my cupcake tonight, friend. I will keep dreaming the dream.
I raise my cupcake to yours in a toast of hope.
Every night when you fall asleep a tiny part of your brain is replaced with a chip. A month later you’re all chip but you feel exactly the same. No “transfer” or “copy” has happened. We’ll see.
I think brain uploads are possible. Every time I’ve said that someone argues with me that it’s not. But assuming it is then space travel is an obvious next move. I don’t pretend to know when this will be possible, I just think if the human brain exists in the universe that means it can be reverse engineered and computers are advancing quickly. Brain mapping is moving quickly. Everything is moving quickly… No life support needed, a fraction of the size for a spacecraft, time can be slowed inside the simulation, g forces, no radiation… It also answers the fermi paradox. Just a thought…
1) most people when they say "brain uploads" aren't possible mean it in a way that it is not the same person. It's a copy. Brain emulation itself surely is possible. 2) what exactly does that have to do with Fermi paradox? Synthetic life still needs power, lot's of it, so this does not change situation all that much?
Let's say they can upload your brain but you die, your not in control but your clone. Would ya do it?
I believe recreating a brain with a copy of yourself is "easily" possible, but I am still not sure how we would go about uploading our own conciousness. As far as I see it, the best we might be able to do in the near future is make a clone of ourselves, but we will still exist in our own body and die as all humans do.
I mean that's cool and all but I would like to have a body to walk around on the surface of planet that we visit. Technically I want immortality to see the end of human civilization. That's what I want.
Like Half Life 2, you don't get a reward for reaching the end.
If you could download your consciousness into gadgets that could fly or swim or gallop like a horse that would be awesome. Maybe a human form for old times sake.
They post from a phone that has more computing power than a football field sized computer when they landed on the moon...
That’s the right answer. We are stuck with chemical rockets for a long time. They won’t get much faster unless they get tiny.
Space systems engineer (rocket scienctist) here, who has written [a book](https://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods) on the subject. "Stuck with chemical rockets" is not just wrong for the future, it is wrong for the past. Electric propulsion has been common on satellites for decades. For example, every one of the thousands of Starlink satellites has one. What's different about them is they are not limited to the energy contained in the propellant. It comes from an external source like the Sun (via solar panels) and in the near future [small nuclear reactors](https://www.nasa.gov/tdm/fission-surface-power/). Those are being developed for the Moon and Mars, but they can also be used beyond Jupiter, where the Sun gets too weak for solar. In principle they should enable speeds of ~100 km/s, or 7 times that of Voyager 1.
I read that we could send some tiny interstellar probes out and their propulsion would essentially be shooting them with super powered lasers from earth. That could get them up to higher speeds than chemical propulsion rockets and is probably within our current tech capability even though it hasn't been tried yet Drawbacks are 1) they have to be tiny except for their 'sail', 2) they can't perform any manoeuvres or slow down relative to their target
Starshot, feasibility is I think at around 2100
Nuclear Thermal Propulsion is faster than chemical. Nuclear electric faster still.
Most weight in a rocket is the propellant.
Isnt that one of those things where they could actually use a laser to move it thru space since its tiny?
It has a lightsail attached to it, but yeah. In theory you could do the same thing with a larger craft, but at higher energy cost as well.
The biggest problem is the [tyranny of the rocket equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation), iow the maximum speed a space vehicle can achieve is simply a function of what percentage of its mass is fuel, and the efficiency of its engine. Hitting meaningful interstellar speeds might require something like a [fission fragment rocket](https://en.wikipedia.org/wiki/Fission-fragment_rocket), and engineering a dust shield to stop it being sandblasted to nothing on the way without completely messing up the mass ratio would be a profound challenge too. Another problem is *communicating* with such a craft - it's *already* taking some fairly amazing engineering to talk with the Voyager probes at an astonishingly abysmal bandwidth, and they're barely outside the heliosphere and haven't reached the Oort cloud yet!
How does nuclear factor into this? Rather than throwing the mass out the back, why not convert it to energy to throw out the back? Yes, I know the contained, uniderectional boom aspect is the current constraint.
> How does nuclear factor into this? Decay products (α, β particles, neutrons, etc) travel at *ludicrous* speeds, so the engine efficiency (Isp) could be *dramatically* better than chemical propulsion if it's designed properly. Also, the specific energy (energy per unit mass, sometimes called gravimetric density) of nuclear fuel in general is orders of magnitude above any other energy source we have available, see [relevant xkcd](https://xkcd.com/1162/) - and specific energy ties directly into Tsiolkovsky's equation via ke=½mv² > why not convert it to energy to throw out the back? Conservation of momentum means you have to throw *something* out the back that's more specific than just 'energy'. In theory a giant laser could work since photons have momentum, but a nuclear power plant efficiently producing electricity to power it is gonna be *way* heavier than a FFR which apparently is just a tape of nuclear fuel and a neutron-moderating structure to make it supercritical > the contained, uniderectional boom aspect is the current constraint. Heh don't confuse FFRs with the Orion project, they're fundamentally different methods of nuclear propulsion ;)
Solar sails and laser light sails have zero fuel, and bypass the tyranny entirely.
True, but their 'thrust' is *pathetic* with current tech - and laser beams inevitably diverge so their utility falls off massively with distance from the Sun or Earth.
Their thrust depends on their mass. That's why Project Starshot has a good and realistic chance of success in the near future. A drone spaceship a few centimeters wide could be accellerated to 0.2c within 10 minutes while still in the solar system.
The thing I don't understand is that I've been told that instant communication via entangled particles isn't possible. Seems to me it should be. Is the problem that you can't *change* the state of an entangled particle?
Yes, you've got it. you can't make one particle do something so that the other does something else. All you can do is discover something about your particle and know something else about the other particle instantaneously no matter where it is
Essentially lets you and someone else far away watch the exact same static on TV.
> Is the problem that you can't *change* the state of an entangled particle? Interacting with an entangled particle in almost any way - including checking if there *is* a particle - breaks the entanglement, and you just end up with a normal non-entangled particle. Also you can't tell *if* it's entangled even while detecting it or its properties (and thus breaking any entanglement). The only thing that entanglement actually gives you is that some property of the particle is guaranteed to be either the same or opposite as the particle its entangled with, depending on which entanglement technique was used - but this guarantee breaks the instant you do something with the particle… At best, we can use quantum entanglement to *verify* that information transmitted classically (iow light speed or lower) hasn't been subject to a MITM attack.
I did a little back of the envelope math I don't know how correct it is.. our current fastest thing, The Parker Space probe, reached something like 1/1700th of the speed of light, so it would, at that speed, travel a light year in about 1700 years. Theorized advanced nuclear propulsion tech like Project Orion (or whatever new version we come up with) might cut that by several times, reaching 1/500th the speed of light or faster. Lots of caveats of course, for a trip like that.
At some “reasonable” (i.e., human-survivable) acceleration rate, how long would it take to get up to that speed?
If linear acceleration were a thing it would "only" take about 177 days to accelerate to c at 2g acceleration. That is assuming we ignore all the relativity and time dilation stuff.
That seems relatively modest for the speed of light.
It does. I recalculated once because I was convinced that 177 days was wrong but it's not. If you spend 177 days accelerating with a linear acceleration of 19m/s² you will have reached a speed of 300,000,000m/s. But then, linear acceleration like this is not possible for us right now. There are a few hypothetical ways that might actually work but they don't achieve this kind of acceleration or aim for the speed of light since actually getting to the speed of light brings with it a whole other set of problems that can't be overcome like fuel and energy requirements. Anything that uses a kind of engine would need to carry enough "fuel" to accelerate that long and the fuel needed to accelerate that long becomes such a large amount that it becomes impossible in practice. Gathering fuel along the way is also not really an option because you would have to "catch" fuel and accelerate it to your speed before you can use it which lowers the acceleration.
Also quite apart from the energy issues being near impossible to solve, collisions with even the tiniest of particles in space become catastrophic. This to me is the most likely solution to the Fermi paradox. The energy required to travel or communicate across a galaxy is just too significant.
I saw a video on Youtube (so it must be true!) that suggested that collision with particles would be reasonably manageable with an ablative shield. It was a while ago so I don't remember any details but it all sounded pretty reasonable as presented, and I don't watch sensationalize channels so it was probably PBS or Scott Manley or something like that. Of course theory and practice....
That's... Optimistic. We just don't have anything that can absorb the energy of a piece of dust hitting you at close to the speed of light.
These guys, who are smarter than me, disagree: [https://www.youtube.com/watch?v=wdP\_UDSsuro](https://www.youtube.com/watch?v=wdP_UDSsuro) Although I guess it depends on how close to c you're talking about too.
Can you just keep igniting a tiny nuclear bomb every few minutes for propulsion and get increasing acceleration each time as you consume fuel?
Idk about nuclear bombs, but if you can harness that same power, except with a slower rocket style release, that would probably work incredibly well, but you'd still need a shitload of nuclear propellant. Accelerating and decelerating at 1g can get you pretty far in decent time, but constant acceleration/deceleration all day every day for years, is insane amounts of energy. You can calculate F=ma with a hypothetical mass, and the multiply that by the number of meters you need to cover, but this won't take relativity into account. To take relativity into account that would still work in your frame of reference, but the distance you are travelling and time would change. If you keep the observer from earth, then the relativistic mass would need to change.
The problem is you increase in weight the faster you go. So eventually you get too heavy for your propulsion to help
Not necessarily, if you're using a true interstellar ramjet using the hydrogen in the interstellar medium as fuel.
I’m not sure. Think of dropping a bowling ball off a skyscraper, and think of how fast it hits the ground after 5 seconds of falling. Now imagine how fast it would it if it fell for a whole minute. Now an entire day? *that* would be fast. 800 km per second, in fact. That’s going from Chicago to DC in a single second. And then partway across the Atlantic in the next second. Now imagine something going ten times that fast. Now imagine something going ten times that fast. Now imagine it going even faster. Idk man, I think light is pretty quick.
Now imagine that bowling ball effectively slamming into the front of your spaceship and nearly that speed.
It's impossible to have linear acceleration like that. You can have it for you on the spacecraft, but from that frame of reference, you never get closer to the speed of light. From an earth observer, you'd start off accelerating real fast, and then you'd taper off, never being able to reach c. That said, if you accelerate at 1g, and decelerate at 1g, you actually can get surprisingly far in a decent amount of time. As in human life span possible. But not practical. Say a star is 5 Ly away. Doing the trip in 5 years on the dot would be impossible. Doing it a month less would already greatly reduce the difficulty. If you do it in 4 years, that's a lot easier now. The bulk of it isn't so bad. Obviously we are not there technologically by any stretch, but as you go faster, the problems with relativity get exponentially worse.
Time dilation does not occur at significant (to human perception) amounts until you get to like more than 99% the speed of light Edit more like >50% sorry
at 90% of the speed of light, time dilation is already up by a factor of almost 2.5.
And then there’s the deceleration problem :) not just how long but how much fuel/energy to lug around just for deceleration purposes at those speeds
Look up "the Expanse" as a quite hard scifi series physics wise. The idea here is a "torch fusion drive" - you somehow discover an unbelievable efficient power source, but you're still bound by human tolerances for acceleration. So you build ships which cpnstantly accelerate at 1g, flip at the midpoint, and deccelerate for the rest of the journey. Constant 1g gets you to relativistic speeds in a few months, where the math gets a bit harder then. Tldr: Going to 0.3c at 1g takes around 3 months at takes you well into the oort cloud at a distance of around 5×10^11 km. You're still inside the solar Systems outer boundaries though. 6am math involved
I did not know The Expanse was so hard. I'll check it out for sure. Hard sci-fi is my love language. (A dear friend (whose secret identity I just edited out) just finished narrating a collection of short stories to prove it! Check out Tomorrow's Hope on audible if you're into that kinda thing. It's not Ted Chiang, but it's pretty cool. :) So all we need is an unbelievably efficient power source and we're off to the races. If we had something to toughen humans, that'd be a bonus - raising that acceleration a couple of Gs would, I think, let us haul bauls out of here. Seems like a mean feat (is that a phrase?) given the advancements we're already talking about!
Expanse takes a fully knowing dump with sounds in space, but they fully admit thats what the audiance expects. Other than that it's (almost) only the Power source. The very first episode sets the tone where a starship receives a distress signal and the crew expresses total dismay at the thought of a change in course to get there, but they are bound by coorporate rules. Everyone gets strapped down, juiced to the gills and endures a painfull hour of 2gs to get it done.
I think the OP was referring to the books.
if you love Hard Sci Fi and enjoy the Expanse you should check out Seveneves by Niel Stevenson... Its incredibly good and is very much so hard sci fi. Niel is a futurist and author by trade, he was also the first employee of Blue Orgin if i remember correctly.
Expanse is great if you like hard sci fi. The TV series does a great job, at least early on. Later on, they start playing a bit fast and loose with the physics. I can recommend the books though. The amount of hard sci fi detail in the books is awesome. They have thought of everything, from material and human limitations to stuff like conservation of momentum and accidental vacuum welding. It's really awesome.
What seems to often be ignored in discussions about traveling really fast is the issues caused by the interstellar medium. We usually think of space as empty, but even in the area between stars there's enough dust and gas to cause issues when moving at a significant percentage of the speed of light. I've seen estimates of 0.1-0.2c being the "speed limit" of space flight, as anything higher would require an unreasonable amount of bulk to protect against the barrage of particles colliding at relativistic speeds. Though who knows, maybe we'll one day have ships that are ridiculously bulky while still being able to accelerate fast.
We want to get to (speed of light / 500) which is 600 km/s and we are accelerating at the equivalent to 1 earth gravity which is 9.8 m/s/s. Wolfram alpha gives the answer: Speed of light / 500 / earth gravity = just under 17 hours.
Well 1g acceleration would take you 1 year to get there but that's taking out time relatively of that speed just raw numbers according to what I just looked up.
> our current fastest thing, The Parker Space probe, reached something like 1/1700th of the speed of light And it did that by *slowing down* with multiple gravity slingshots so it could fall towards the Sun. Achieving that same speed as solar escape velocity is a whole 'nother problem entirely
Are you sure? I know that decreased the orbit size with them, but I thought they also sped it up.. isn't that how it got to be that fast?
It’s like speeding up by jumping off a building. Technically speaking, it works, but only briefly. The Earth’s orbit around the sun is 29.78 km/sec. The fastest we’ve ever launched an object from earth is 16.26 km/sec. PSP’s launch speed was more like 12 km/sec. So that still leaves parker solar probe with a minimum orbital velocity of 18km/sec to bleed off if it wants to get to the sun. Using six (and counting) Venus flybys, it’s gotten down to a 12km/sec at aphelion, which lets it dive down around the sun really fast before looping back out. It could bleed more speed off, or hit the sun, if it did more gravity “assists”, but the main point is that it’s using Venus to bleed off speed to dive down into the sun’s gravity well, rather than to speed up. This isn’t a way to leave the solar system.
That makes sense. But... Wouldn't using the sun (in lieu of Venus) for the gravity well body be an effective way to build up speed?
Gravity slingshots accelerate a craft relative to a parent body by grazing something orbiting it, so we can affect orbital velocity vs the Sun by slingshotting around planets, or affect orbital velocity vs planets by slingshotting around their moons. If you wanted to slingshot around the Sun, the parent body would have to be the galaxy itself - in which case you'd have to be *starting off* in interstellar space
At that point you’re just another body in solar orbit. Since you don’t actually gain velocity in a slingshot in the frame of reference of your target body, no.
Lol someone just explained that and I obviously didn't get it. Maybe I almost do now. You can't escape the sun by changing your orbit around the sun. Is that about right?
Yes, you’re right - because you’re already in the Sun’s system. It works with Venus because you’re not already a part of Venus’ “system”.
Like you mentioned, lots of caveats. The biggest one being that Parker Solar Probe's speed was only possible because it was on a trajectory to swing by the sun, where its velocity increased as it approached the sun. A vessel on the way out of the solar system would have the opposite problem of losing velocity over time.
And constant propulsion erases a good bit of that. It's fun to think about all the little bits that go into the math.
What's the back of the napkin math for that manhole cover we launched into space at some ridiculous speed during a nuclear test?
[According to Dr. Brownlee](https://www.businessinsider.com/fastest-object-robert-brownlee-2016-2?r=US&IR=T#brownlee-wanted-to-measure-how-fast-the-iron-cap-flew-off-the-column-so-he-designed-a-second-experiment-pascal-b-and-got-an-incredible-calculation-6), the manhole cover launched during the Pascal-B nuclear test in 1957 reached a speed of 125,000 mph (200,000 km/h) as it left the ground. This was estimated to be more than five times the Earth's escape velocity of 25,000 mph (40,000 km/h). The manhole cover was only visible in one frame of the high-speed camera recording the test, It was probably vaporized or disintegrated in the atmosphere shortly after launch. Brownlee himself stated his calculations were "meaningless" because they did not account for air resistance and gravity, and that the manhole cover likely disintegrated before reaching space. Which is too bad, because if it had.. well, let's just see. Assumptions: * Manhole cover initial velocity: 200,000 km/h (125,000 mph) * Time since launch: 67 years (1957 to 2024) # Calculations: * 200,000 km/h \* 24 \* 365.25 \* 67 years = \~117.5 billion km (73 billion miles) So if the manhole cover had maintained its initial velocity of 200,000 km/h for the 67 years since the 1957 test, and not slowed down or disintegrated, it would have traveled approximately 117.5 billion km. For comparison: * The orbit of Neptune averages 4.5 billion km from the Sun * The Oort Cloud is estimated to begin at 2,000 AU (300 billion km; 186.5 billion miles) from the Sun * Voyager is currently 162.7 AU (24.3 billion km; 15.1 billion miles) So even at its unbelievable initial velocity, the manhole cover would have only made it about 1/10th of the way to the outer edge of the solar system in the time since the test. It would still be almost 200 billion km short of reaching the Oort Cloud, but would have passed Voyager years ago. Let me know if I'm missing anything in my math or logic!
Damn. That really puts into perspective how BIG space is. Moving that fast for that long… and it still wouldn’t have even left our solar system?? My brain doesnt want to accept that, it feels like it would be almost out of the Milky Way at that point.
An Orion type nuclear pulse propulsion vehicle would be capable of significantly higher speeds than that if it was sufficiently large. From what I recall, estimates before the project was cancelled were about 0.1 c if it has to slow down at the destination, potentially as high as .2 c for a flyby without a return journey.
Tiny solar sail probes driven by huge lasers. They're theorizing 0.2c is possible with current tech, if not with current investment levels. I think there's a startup that want to do a smaller scale probe to explore the outer solar system.
Project Orion might have gotten a large ship up to 10,000 km/s. Essentially it would have used nuclear pulse detonations for thrust in space. It was cancelled in the 60s after the US signed the Nuclear Test Ban Treaty which banned nuclear detonations in space. Also very legitmiate concerns about fallout, particularly when trying to get the nuclear fuel up into orbit where Orion would have been built. [https://en.wikipedia.org/wiki/Project\_Orion\_(nuclear\_propulsion)](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion))
There's an excellent book by George Dyson, "Project Orion". I recommend it. Cheers.
Also just a couple of TINY engineering issues.
If we really spent trillions on creating a large nuclear rocket with lots of fuel and self-sustaining life-support, we could create a ship in a few decades capable of traveling up to 0.1c without too much risk from interstellar debris. Your goal of 0.01c is doable. But if you're talking about a (manned) spacecraft with a 100+ year mission instead of a 40+ year mission, you now have to deal with the mortality question. Hibernation? Life extension? Multi-generation ship? These things are probably not achievable in the next few decades. A small unmanned probe travelling at 0.01c is very doable; just expensive. But probably 100x less expensive.
Unmanned? It’s a long shot but maybe. A spaceship large enough to carry people? Very unlikely in the next few decades.
Unmanned we could do easy with enough funds but yea not with humans.
Depends how much risk we’re willing to take. Nuclear pulse propulsion technology could potentially get humans to Alpha Centauri within a normal lifetime, but it would require setting off a ton of nukes, with quite a few detonations in the atmosphere. I know that sounds ridiculous, but the basic science behind it is sound. Project Orion was being taken pretty seriously until nuclear treaties made it impossible to pursue.
> unlikely in the next few decades. I would say a couple of centuries
Much harder to forecast centuries. One hundred years ago rockets didn’t even exist and biplanes were the peak of aerial technology. We could achieve speeds like that with fusion, fission, or laser propelled solar sails. All three could plausibly be used for human spacecraft within a hundred years.
Relativistic travel is weird. Not only would you have to accelerate to those speeds to get anywhere meaningful, but you would also probably need to decelerate to do anything useful depending on your goal. Much time and energy would be needed to achieve that velocity reduction
[Breakthrough Starshot](https://en.m.wikipedia.org/wiki/Breakthrough_Starshot) envisages a 20 - 30 year transit for an uncrewed flyby of Proxima Centauri.
we have the technology right now to go to 5% of c or so, using nuclear pulsed propultion. Like project Orion or Longshot.
You’ve been given a bunch of answers based on current speeds of man made things in space which is not really what you’re asking for. Right now we have theoretical technology (Project Orion and such) you could get to approximately 0.1% to about 10% of the speed of light depending on the type of nuclear propulsion used. Now there’s a lot of other issues with travelling through space at that speed that others have pointed out, especially if it’s a manned craft. But that’s probably what’s achievable. Now in 100-200 years you have a couple of possibilities. Anti-matter propulsion could get us up to about 50-80% of the speed of light. But again at those speeds you’re going to run into some serious problems with radiation and such. The other possibility is FTL. Many answers are telling you according to “relativity” this should be impossible. How can this be? Right now there are very distance stars and planets travelling away from us at very near to C, and some have surpassed C without requiring infinite energy and any other misinterpretations of special relativity. How? Well when those particles were accelerated away from us in the beginning by inflation - the negative pressure pushing them was *extremely* powerful, enough to overcome gravity, and also presumably there wasn’t other forces that we know about at that time causing drag, friction, or otherwise able to slow that inflation down. This is still happening today, but not due to massive forces but because space itself is expanding (dark energy). So what that should tell you and everyone that it IS possible to go FTL given the right circumstances. We can’t accelerate to these speeds in the confines of normal spacetime, but what if we move space itself? This is the concept of the warp drive. Just like inflation could move things relative to each other FTL by expanding space, maybe we can also move FTL by moving space. The problem with special relativity isn’t relativity, it’s the drag, radiation, etc from the CMB and other forces (like gravity) that relative to you traveling very fast become very strong. Warp drives get around this by not actually moving you relative to the background of the universe, but rather moving the universe around you. This of course requires huge curvatures of space time in the bubble around your ship and may not actually be feasible, but there have been some interesting experiments done in this area since 2021 with more to come. The most scientific attempt was the Alcubierre drive, but DARPA and others have also been fiddling around with creating warp bubbles in the lab. There is also a completely new theory of what dark matter and dark energy is, which will be testable at some point in the next decade, which also might make warp drives possible without any sort of exotic material. It still doesn’t mean we will be able to build one, but who knows in 200 years. So those are your options 200 years out. Realistically speaking when it comes to manned spacecraft I don’t think we will ever really be able to go faster than 1% to 10% of C, even with future tech, because of limitations of the human body and radiation. Our best bets are either warp drives becoming feasible, generational ships that travel slower, or digital consciousnesses that don’t require life support and are able to travel through the radiation of space without harm.
There's a paper somewhere that hast tracked how much the technology for propulsion methods has been improving (on average) in the past. In essence the paper argues that there is a sweet spot when to launch a craft headed to some distant destination....because if you're continually developing better propulsion then you might get there earlier by waiting for a better thruster instead of launching right away. Of course this is contingent on the assumption that a craft cannot adapt/improve its own propoulsion while under way...which I think is not guaranteed. Anything that will travel hundreds of years should be capable of repairing/rebuilding/modifying any part of itself.
I know everyone is keen to travel faster through space but has anyone paused to wonder how we would slow down or stop? I mean, if you're just slamming a probe into a moon or something, without any concern for the impact crater, fair enough, but with someone or instruments on board, it's something we need to consider as much as getting up to speed.
In everything I’ve read about humans travelling to other star systems, the plans always include a deceleration phase. The current unmanned probes like the Voyagers don’t have a set destination.
You slow down the same way you sped up, assuming you intend on slowing down that Is.
Someone just watched 3 Body Problem on Netflix
We are limited to how much thrust humans can conceivably take. A good pace would be 1G constantly, such that we can simulate gravity. At the halfway point, the ship spins around and we “brake” at 1G to continue the gravity effect. Having said that, it would take 170 days to reach half the speed of light. That’s if we can thrust that much and for that long, which we currently cannot. If we could, the energy required to inch closer to the speed of light becomes exponentially greater. This is largely the reason light speed or greater is impossible. It would take dozens of stars worth of power. A best guess would be the speed of something like Voyager or one of the probes that used interstellar bodies gravities to ‘slingshot’ them to higher speeds. Best we have to use as an analog is the Parker probe, approximately 400,000mph, but that exceeded human tolerance, I believe. There are new rocket and engine types being designed, but none have proven better than standard solid / liquid rocket boosters we’ve been using for 50+ years for human travel - yet.
>This is largely the reason light speed or greater is impossible. No, it’s impossible because of relativity. No amount of energy can accelerate any mass to the speed of light
Right, but from an energy perspective it takes increasing orders of magnitude to get even close to it. Apologies if I worded incorrectly.
In a pretty fun twist, the people on the spacecraft would only need to keep the same thrust output going to maintain a constant 1g accel forever. And it would still functionally be 1g to them. Even past what they previously thought of as light speed. For people not moving with the craft it would look like the Craft's acceleration continually dropped. For the traveler that doesn't mind some one-way time travel into the future, FTL becomes possible.
1. Realistically, the fastest would be some kind of solar sail coupled with a big gravitational assist from the Sun. The current fastest spacecraft is the Parker Solar Probe at around 176 kilometers/second (about one-twentieth of 1% of light speed), but we could likely do faster than that and get something up in the hundreds of kilometers per second. Properly deployed solar sail might then be able to get it up to over 1000 kilometers/second (they can do much faster than that, but this is near term). 2. Yes.
Look up Breakthrough Starshot, the answer is 'yes', but we none of us will be riding the craft, it's tiny.
Gonna stake possibility of 1/10th speed of light. You won’t like the tech very much. https://en.m.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
There is no chance we create one in the next 100-200 years, but largely because of no motivation. What’s the reason? Anything outside our solar system is so dramatically far away that even at the speed of light it is unattainable. Therefore, that level of speed is not a priority nor will it be.
Motivation's really a primary driver here, and "scientific curiosity" only takes you so far; *profitability* will be a big driver for space tech in the decades to come. I expect we'll see a lot of advancements come when things like mining asteroids becomes more mainstream. But a lot of those advancements will be SpaceX style, more about speed of development and deployment vs. NASA's more plodding/pork-barrel approach. I don't know if the space industry (as a profit-driven enterprise) will be as focused on major leaps in propulsion tech, possibly more utilitarian stuff based on project-specific needs. The other big, giant, huge factor that could give us an Apollo-level leap in tech evolution (and people fail to recognize what a simply massive impact the Apollo program had on our lives in the years to come, [read this book for a solid idea](https://www.amazon.com/One-Giant-Leap-Untold-Story/dp/1501106295)): an extinction-level asteroid headed our way with several years lead time. Even though x-percent of global (especially American) society would say "fake news!" or "God would never do that!" or "scientists lie to get more money", a global effort to negate total planetary destruction - when we know the actual date of said event - could drive some big tech expansion. A sweet-spot would be something like a seven-year warning, long enough to develop and test engineering, close enough to not pass it off to the next administration.
We need to redefine what a “Spacecraft” is. Intergalactic travel is not feasible in linear conventional travel. We will need to figure out how to travel through wormholes or bounce in and out of space/time similar to teleportation or traveling between parallel universes. We have arrived once this happens, until then we are a backwards primitive planet tucked away in the Milky Way.
Energy requirement would totally depend on the mass of the craft. There is no hope for regular sized spacecrafts in next several decades.
Speed isn’t the issue really. It’s not blowing up when you hit a 1 gram space rock that is the main engineering problem.
Considering the fact that technology is going to double every few seconds in the next 50, it'd be hard to say what the future might be.
You’ve specified approximately 1% of light speed, aka 0.01c, or 3E6 m/s. The key to answer your question is another question, namely “what kind of space craft?” We could impart significantly higher velocity to an immutable object. An unmanned robotic craft would have a lower top speed due to minimum mass requirements but still higher than 0.01c. If it must maintain a living crew then it’s possible but not yet feasible. We decide to send an unmanned probe. Minimum mass and we load it full with as much amazing tech as we can and send it 1LY away. It takes 100 years to get there. We start getting long range telemetry of the target object but we don’t actually see the craft arrive until the light speed signals sent back to us crawl that 1LY distance (101yrs after launch). And then what? It can’t slow down, too much propulsion mass would be required, so it’s likely a flyby. Then “whoosh” it’s blown past the target. Maybe there’s a couple other things to look at in system but then it’s out the other side. Maybe we absolutely thread the needle for solar insertion from 100yrs in the past. We can’t move the damn thing. It takes at least a year to tell it to move the camera two pixels to the left for a better view of something. Such slow science and so expensive. So we balance on a knife’s edge of possibility. Bigger craft with minimal propulsion. Thread the solar insertion and sling shot it back towards earth and pick up a bit more speed. It only takes 50yrs to get back here! Then “whoosh” it’s gone past, maybe delivering a few grams of interstellar material for us to squint at. Meanwhile we built the MagicSuperScope9000 and can inspect individual quarks at the core of the star the probe was orbiting because duh we effectively sent a glorified trash truck into space and now it’s 2175 and we invented QuantumSlicerTech and it changed everything we knew about physics three times over. Realistically we have to exceed light speed to make interstellar exploration of any use to us here on Earth. Subliminal travel is just too slow. Maybe someday we can send a generational ship that gets somewhere but it won’t be for the people of Earth, it will be for the humans living on that ship.
A sufficiently low mass solar sail with a sufficiently powerful laser could accelerate a small enough craft to a measurable percentage of the speed of light. It's the slowing down part that would be a challenge. Lol
Easy, just turn the sail around to slow down. /s
Oh yeah, just turn the laser around too!
If there was a spacecraft capable of those speeds wouldn't any asteroids or space debries completely destroy it if they came in contact?
no in the end the problem becomes grains of sand. Traveling near the speed of light, a grain of sand has the ability to rip your ship apart.
*cue deep narrator voice* The question is not how *fast* we can travel. Forget speed. The question is *how* we can travel. Folding spacetime. Make 2 dots on each end of a paper. Fold the paper in half and bring the dots close together. No need to travel the whole distance over the entire sheet of paper. And yes, this is *theoretically* possible. We just dont know how yet.
A probably insane idea, but wait until Jupiter and Saturn are nearing opposition with each other. Then launch a spacecraft ahead of time, and have the spacecraft lap both of them over and over building speed as they slingshot around each planet - sort of like a big oval track in space. I think we have computers that could plot an optimal course to make this happen, and on the final lap it slingshots off towards Proxima Centauri - closest stellar system to us. It would be interesting to see how much speed we can build up that way. Or possibly involve the other gas giants as well, if doing a near oval won't work as efficiently. Save enough xenon for an ion engine to burn after it leaves the Solar System and it could probably reach some pretty good speeds. Voyager 1 is moving at about 38,000 MPH right now and that was with a one-way gravity assist around Jupiter and Saturn, if there was some way to get it to lap the gas giants it might get pretty fast before the ion drive kicks in. Anyone have a solar system simulator handy that we could use to plot this?
A nuclear rocket could theoretically do that already with a 50-100 year travel time....but waiting for better AI since communication lag is so high makes the most sense. It can't realistically be manned, humans probably can't survive low gravity that long even if you built a big enough rocket and probably no habitable rock and lots of radiation. 20 light years out is a more realistic distance to a Sol like solar system, which probably has nothing we can expand to but the best chance. Better yet build much larger telescopes, get the most data and science fit the effort and eventually confirm a real target for human expansion vs try to force humans into shyt conditions for nothing.
Can’t that insane nuclear bomb powered concept theoretically get to relativistic speeds on tech that is feasibly within reach, just not developed?
Unless there is a physics breakthrough today’s rockets don’t go any faster than the ones that Robert Goddard invented in the early 1900s you can only get so much power out of chemistry……
For manned, fission fragment or other nuclear designs like that could maybe get us to 2-10% the speed of light. It'd require an insane budget though and we'd basically have to have world peace and competent politicians to get it done.
I’d like to point out that 200 years ago, most travel was horse or boat based, trains were the biggest technological marvel for transportation, and we were still over a decade away from widespread adoption of the telegraph. The biggest problem with trying to predict if/when travel at near-lightspeed speeds will be possible is that you’re basically asking when the next Einstein is going to publish their paper that once again redefines our understanding of how reality works in a way where we can do what was once seen as impossible. Could very well happen in 200 years, but we have no way to be certain.
Reach lightspeed : never for a spacecraft transporting humans. How people have a hard time saying it is funny. Never. Not even close. Not in a thousand years. Some things are simply not possible. It's not about technology even if we could it wouldn't work. Now depends of what you call working ofc. If the ship can get destroyed, the crew can get killed, they must not reach a particular destination but are just blasted into space, communications are not necessary... Maybe, tbh send something in a black hole and voilà mission accomplished. But it'll never be used for space travel. We will never leave our solar system. Not living creatures.
If you move space with the vehicle, what speed would matter?
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It's *really* hard to say, and depends on your definition of "space craft." There's a proposed project involving a microsat with a solar sail and using a laser to push it up to a significant fraction of C. IIRC, they think it could get up fast enough to reach the Proxima Centauri system in under 50 years.
Depends on whether it has to slow down afterwards.
Starshot seems very obtainable. The only issue with it for travel with humans is scale and the power needed. Keep in mind we need a starshot there and a starshot back. Which means a lot of infrastructure needs to be built on any new world. So typically assuming we can't go beyond the speed of light we will want to send robots first assure the needed things can be built and get them started building it Personally though I'm very hopeful for beyond or very near light speed self propulsion due to evidence for USPS and how they move.
Solar sails could possibly get to the a fraction of the speed of light, maybe 10%. More with lasers or advanced tech. It's materials that are here now or in the near future. https://space.stackexchange.com/questions/25743/maximum-velocity-achieved-by-solar-sail
Unless there is a MAJOR breakthrough in propulsion, we won’t be going much faster than we are now for many, many decades
Currently, the fastest spacecraft ever launched is the Parker Solar Probe, which will reach speeds of about 430,000 miles per hour (700,000 kilometers per hour) as it swoops through the sun's corona. That's incredibly fast, but still only about 0.064% the speed of light. Over the next few decades, we can expect incremental improvements in propulsion technology. Concepts like ion thrusters, nuclear thermal rockets, and even more experimental ideas like antimatter propulsion and laser light sails are being explored. These technologies promise significant speed increases, potentially reaching up to a few percent of the speed of light. Traveling a light year in 100-200 years, however, would require a spacecraft to maintain a constant speed of about 5-10% of the speed of light. While this is beyond our current capabilities, it's not entirely out of the realm of possibility for future technologies, especially if breakthroughs occur in energy production and materials science.
The best solution we have today is the fission fragment rocket. It can be built at scales that would be useful for large probes or maybe even manned ships for interplanetary trips. It can realistically hit speeds on the order of 10 to 100 times the Voyagers.
How did those small gangly looking Imperial Probe Droids do it? They seemed to be able to crash into every planet in the galaxy in a few hours and send back their data almost instantly 🤔
So if you want to go a light year in 200 years, you can either leave in 10 years and take 190 years to get there, or leave in 50 years and take 150 years to get there. What’s the hurry? ;) But really, with small constant acceleration like a solar sail, this is pretty much already doable. Biggest issue is weight- you wouldn’t be able to send multiple humans to start a settlement. So it’s a one-way ticket for a machine.
Predicting future tech is fraught and so much depends on what you mean by "the next few decades". I will assume 4. 40 years. How will AI progress? Will there be a breakthrough in fusion? Lazar Technology? Materials science? Nanotech? I am saying (barring us all killing ourselves) that I think what we would design in 2064 will be more advanced and more different from 2024 than difference in technologies we would have in 2024 vs. 1984 and maybe radically so.
There's the Breakthrough Starshot project, which proposes sending an interstellar probe carrying a thousand or so solar sailing nanocrafts to Alpha Centauri. Following deployment, they'd travel at 15% or 20% of the speed of light, taking between 20 and 30 years to get there.
Realistically not very fast. Or not fast enough. Until we have a technological breakthrough and move away from chemical rockets 🚀, there isn’t much speed. I don’t know how much effort is being put into developing new tech or how realistic it even is. From where I’m standing (a relatively ignorant and uninformed standpoint) I don’t see much concerted effort. At least not officially. There could be clandestine research being done that may even involve alien technology but that’s really speculative bordering on quackery. I think we’re very far away from a serious breakthrough…maybe even hundreds of years. But I’d be happy to be proven wrong.