Well, even if we could not reach such a planet in a reasonable time yet, a research like this could still be very useful for many reasons.
It could help us learn how our habitable environment works and operates, it might be applicable for terraforming or habitat construction.
There is also a non-zero chance of some sort of life, possibly intelligent developing in such an environment (as proven by our sample size of 1). That life can be active at the moment (from our PoV - light speed and all) or was active in the past, so we should look for bio signatures or even signs of mega scale engineering.
The answer is actually yes if you're willing to wait.
Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical. We've barely even left our own planet, and we've managed to throw a few chunks of metal out of our solar system so far. We lack the industrial capacity to build an interstellar ship, we do not lack the physics.
IIRC, it is possible to get anywhere in the observable universe in one human lifetime assuming 1g of constant acceleration.
This does not permit you to slow down and halt at your target, which greatly increases travel times.
It is also effectively a one-way ticket for anything other than objects in our immediate stellar neighborhood. If you turned around and returned to Earth after getting to an object 1,000ly away—still well within our own arm of the galaxy—at least 2,000 years will have passed on Earth. It’s probable that no civilization you know of would still exist, nor would anyone be able to understand your language.
This isn’t even beginning to address the problem of running into stray atoms at 99.99…% of the speed of light. Or god forbid a handful of stray molecules. We also haven’t discussed the real elephant in the room which is the sheer amount of energy required to accelerate a human and human life support systems at 1g for several decades.
Also, how much fuel do you need to bring along to accelerate a human and life support system and the whole craft including fuel, for a lifetime? Is it larger than a planet?
Actually, even something as primitive as a NSWR (https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket) can reach a good percentage of the speed of light after basically processing a comet for fuel. From the Wikipedia article:
"The design and calculations discussed above are using 20%-enriched uranium salts. However, it would be plausible to use another design which could achieve much higher exhaust velocities (4,725 km/s) and use a 30,000-tonne ice comet along with 7,500 tonnes of highly enriched uranium salts to propel a 300-tonne spacecraft up to 7.62% of the speed of light and potentially arrive at Alpha Centauri after a 60-year journey."
Sure, not 99% the speed of light or continuous 1 g acceleration but IMHO good enough for an oversized nuclear squirt gun.
Since we're already in the realm of far out engineering, you could get the energy from a laser beam from a source orbiting the sun. Your spaceship would have some kind of array to capture the energy beam.
This gives you energy, but I'm not sure how to turn that into velocity. Presumably you'd want some kind of ion beam emitter on board to propel your craft forward. Halfway through the journey, you'd turn the ion beam around to decelerate as you approach your destination.
In the Arthur C Clarke novel Songs of Distant Earth, spacecraft pushed huge blocks of ice ahead of them to absorb stray interstellar dust.
Another option is to visit as many massive objects as possible on the way there, doing gravitational slingshots until you're half way, and then gravitational brakes on the approach. Of course now you're taking detours, but since certain amounts of fuel make the trip impossible, any workaround at all is an improvement. What's an extra few thousand years between friends?
Less if we just send some eggs and sperm and spin up a human on arrival. We can construct a larger life support system out of things we find at the destination.
Or better yet, send some cancer cells so they can replicate during the journey, then switch from cancer mode to gamete mode for the final generation. That way they're fresh when you need them.
>Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical.
This was provocative and intriguing so I looked into it and this is my understanding of some of the options (theoretically).
First, "interstellar" means between stars and the closes star is 4.2465 light years away (Proxima Centauri in Alpha Centauri star system) so I used that. c=speed of light
- Chemical (Voyager), ~0.006% c: ~75,000 years
- Nuclear pulse (Orion), ~3-10% c: ~40-130 years
- Fusion (Daedalus), ~12% c, flyby: ~35 years
- Laser sail (Starshot), ~20% c, flyby: ~21 years (gram-scale probes only)
- Antimatter, ~20-30% c stopping: ~14-21 years; ~50% c flyby: ~8-9 years
Nuclear pulse surprised me in particular. My understanding is you basically just detonate a bunch of nukes to propel yourself. There are legal hurdles not to mention fallout, but it sounds like the physics of simply getting there in 40+ years (not stopping, mind you) is possible with todays physics. That's pretty amazing and I had no idea.
Yeah - and the mass fraction is also very good for Orion. You can basically build your ship from boiler plate (and you kinda have to) in a shipyard, no need for fragile ultra light stuff.
Also past LEO you don't really have issues with fallout.
So the only real hurdle is securing the supply of couple thousand nuclear bombs for the trip.
But if you told people in 1903 that you can build a plane that will get 850 people 14000 km but you need 250 tons of kerosene to fuel it, they would also think you are insane (e.g. an Airbus A380).
But over time, even with Orion, people will just get used to it. :)
We don't lack the industrial capacity either, we mostly lack a good reason to spend these resources in that direction.
And IMHO that's the main explanation for the Fermi paradox: we don't see aliens everywhere because they don't have a good reason to colonize other planets than their own either.
Would that not also imply that improvements in ease of access to space, increase of energy production and -price reduction all level off before it becomes easy and affordable enough that mere curiosity would suffice to make it possible, for ALL civilizations?
Travelling to another star would require a fully self-contained spaceship with energy, life support, food, medical facilities, even production facilities able to function for centuries or millenia. We simply don't know how to do that.
Space is, and I must emphasize this in the strongest possible terms, really FUCKING BIG and dangerous GRBs tend to be tightly focused given the inverse square law.
It's highly unlikely that a ship gets hit by a GRB.
On the other hand, general radiation gets worse the faster you go, so you need shielding either way. All you have to do is line the walls of your ship with a shit ton of water, which can be mined in space.
I'm reminded of the joke that the most dangerous thing in the ocean is all the water.
We don't have fuel sources that can run long enough for the trip, and deep space won't have enough solar radiation. We would need reliable mining spots along the way to replace metals made brittle by exposure or punctured by micro asteroids.
Even travelling at 1% the speed of light, stray hydrogen atoms become a problem. Not counting acceleration or deceleration time, that would be over 400 years just to get to the nearest star, let alone one with a habitable planet.
Maybe the previous poster was referring to the Kuiper Belt and/or the Oort Cloud? There's certainly plenty of water ice out there, with no particularly deep gravity wells to worry about.
Collecting it while usefully en route to another star system seems like it would be tricky from a delta-v perspective, but maybe the solution is to:
1) build a small worldship from an appropriate asteroid
2) fill your internal ocean in the outer solar system over the course of a generation or three
3) dive back down the gravity well for a gravitational assist from the Sun as you head to your interstellar destination
4) en route, slowly use part of your ocean as propellant, while living inside the rest of it as shielding
> (GRBs) are extremely energetic events occurring in distant galaxies that represent the brightest and most powerful class of explosion in the Universe.
> The sources of most GRB are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime)[11] and extremely rare (a few per galaxy per million years).
> All in all, a GRB within a few kiloparsecs, with its energy directed towards Earth, will mostly damage life by raising the UV levels during the burst itself and for a few years thereafter.
I'm guessing without an atmosphere protecting a ship it'd be a bit worse? But it's like winning a very bad lottery to get hit by one. I guess if you're traveling thousands of years in deep sleep odds get higher?
It wouldn’t be that fun to live on one. The article says picture paradise, but we’re talking about potentially 1.5-2g with a dense atmosphere; we’d feel terrible all the time. Also whatever biology is in that planet is probably not compatible with us; we likely wouldn’t be able to eat it. Finally once you land, you’re screwed and stuck there. Traditional chemical propellants barely work for our planet, we’d need new ways of taking off for higher escape velocities.
My hypothesis has always been, hey, have enough kids out there, and sooner or later, they'll learn enough about the physical sciences to at least explore far away worlds. (If not go there in person.)
But yeah, expecting we can get there with what we currently know is a bit naive. We need to, <gasp>, horror of horrors, fund more research.
Space is really big. We might be able to get a probe someplace, but can't get data back. We don't even have the ability to detect a civilization as advanced as us at the nearest star (only 4 light years away, but probably can't support life as we know it) if they put all their resources into sending us a message, and we spend all our resources to look at the right moment.
There are laws of radio propagation that mean I doubt we ever will.
In turn this means a probe needs to get there, and then come back. That is a lot of energy...
I can't say it is impossible, but it is highly unlikely the laws of physics will ever give us a loop hole big enough to pull this off.
Any anthropic observation requires merely a satisficing condition, which generally means that most requisite conditions are not optimal, including consciousness :)
Well that makes sense as this one is becoming less habitable by the day
And it isn't the first time lifeforms on Earth made their own planet less hospitable. See the Oxygen Catastrophe or the Azolla Fern Event.
We just need to find where The Ancients buried the Stargate on Earth. Let's gooo!
Good news! https://news.ycombinator.com/item?id=50067414
All I've found so far is black materia.
https://archive.is/yIYpb
Is there any plausible way for a human to ever reach one given what we know about physics at the present?
Well, even if we could not reach such a planet in a reasonable time yet, a research like this could still be very useful for many reasons.
It could help us learn how our habitable environment works and operates, it might be applicable for terraforming or habitat construction.
There is also a non-zero chance of some sort of life, possibly intelligent developing in such an environment (as proven by our sample size of 1). That life can be active at the moment (from our PoV - light speed and all) or was active in the past, so we should look for bio signatures or even signs of mega scale engineering.
Yes, easy assuming multi-generational arcologies.
There are plenty of designs that get you to 0.1c or above if you are Kardashev 2, things like light sails powered from the Dyson sphere.
Nothing plausible for anyone living today AFAIK.
The answer is actually yes if you're willing to wait.
Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical. We've barely even left our own planet, and we've managed to throw a few chunks of metal out of our solar system so far. We lack the industrial capacity to build an interstellar ship, we do not lack the physics.
There’s a huge asterisk here.
IIRC, it is possible to get anywhere in the observable universe in one human lifetime assuming 1g of constant acceleration.
This does not permit you to slow down and halt at your target, which greatly increases travel times.
It is also effectively a one-way ticket for anything other than objects in our immediate stellar neighborhood. If you turned around and returned to Earth after getting to an object 1,000ly away—still well within our own arm of the galaxy—at least 2,000 years will have passed on Earth. It’s probable that no civilization you know of would still exist, nor would anyone be able to understand your language.
This isn’t even beginning to address the problem of running into stray atoms at 99.99…% of the speed of light. Or god forbid a handful of stray molecules. We also haven’t discussed the real elephant in the room which is the sheer amount of energy required to accelerate a human and human life support systems at 1g for several decades.
Also, how much fuel do you need to bring along to accelerate a human and life support system and the whole craft including fuel, for a lifetime? Is it larger than a planet?
Actually, even something as primitive as a NSWR (https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket) can reach a good percentage of the speed of light after basically processing a comet for fuel. From the Wikipedia article:
"The design and calculations discussed above are using 20%-enriched uranium salts. However, it would be plausible to use another design which could achieve much higher exhaust velocities (4,725 km/s) and use a 30,000-tonne ice comet along with 7,500 tonnes of highly enriched uranium salts to propel a 300-tonne spacecraft up to 7.62% of the speed of light and potentially arrive at Alpha Centauri after a 60-year journey."
Sure, not 99% the speed of light or continuous 1 g acceleration but IMHO good enough for an oversized nuclear squirt gun.
Since we're already in the realm of far out engineering, you could get the energy from a laser beam from a source orbiting the sun. Your spaceship would have some kind of array to capture the energy beam.
This gives you energy, but I'm not sure how to turn that into velocity. Presumably you'd want some kind of ion beam emitter on board to propel your craft forward. Halfway through the journey, you'd turn the ion beam around to decelerate as you approach your destination.
In the Arthur C Clarke novel Songs of Distant Earth, spacecraft pushed huge blocks of ice ahead of them to absorb stray interstellar dust.
Another option is to visit as many massive objects as possible on the way there, doing gravitational slingshots until you're half way, and then gravitational brakes on the approach. Of course now you're taking detours, but since certain amounts of fuel make the trip impossible, any workaround at all is an improvement. What's an extra few thousand years between friends?
So there is also the idea of a ramjet that uses interstellar hydrogen as fuel for fusion, which provides energy & propulsion: https://en.wikipedia.org/wiki/Bussard_ramjet
Some recent findings do give it lower feasibility though.
Less if we just send some eggs and sperm and spin up a human on arrival. We can construct a larger life support system out of things we find at the destination.
Or better yet, send some cancer cells so they can replicate during the journey, then switch from cancer mode to gamete mode for the final generation. That way they're fresh when you need them.
Yeah, I added that I think around the time you replied :)
>Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical.
This was provocative and intriguing so I looked into it and this is my understanding of some of the options (theoretically).
First, "interstellar" means between stars and the closes star is 4.2465 light years away (Proxima Centauri in Alpha Centauri star system) so I used that. c=speed of light
Nuclear pulse surprised me in particular. My understanding is you basically just detonate a bunch of nukes to propel yourself. There are legal hurdles not to mention fallout, but it sounds like the physics of simply getting there in 40+ years (not stopping, mind you) is possible with todays physics. That's pretty amazing and I had no idea.Yeah - and the mass fraction is also very good for Orion. You can basically build your ship from boiler plate (and you kinda have to) in a shipyard, no need for fragile ultra light stuff.
Also past LEO you don't really have issues with fallout.
So the only real hurdle is securing the supply of couple thousand nuclear bombs for the trip.
But if you told people in 1903 that you can build a plane that will get 850 people 14000 km but you need 250 tons of kerosene to fuel it, they would also think you are insane (e.g. an Airbus A380).
But over time, even with Orion, people will just get used to it. :)
We don't lack the industrial capacity either, we mostly lack a good reason to spend these resources in that direction.
And IMHO that's the main explanation for the Fermi paradox: we don't see aliens everywhere because they don't have a good reason to colonize other planets than their own either.
Would that not also imply that improvements in ease of access to space, increase of energy production and -price reduction all level off before it becomes easy and affordable enough that mere curiosity would suffice to make it possible, for ALL civilizations?
We do lack the technological capacity.
Travelling to another star would require a fully self-contained spaceship with energy, life support, food, medical facilities, even production facilities able to function for centuries or millenia. We simply don't know how to do that.
We are at least 1000 years away from being anywhere close to this.
Generation ships with plasma sails, probably.
And what happens when they encounter a GRB?
Interstellar travel is not a propulsion problem. It's a space travel problem. The medium itself, is the vast majority of the problem.
Space is, and I must emphasize this in the strongest possible terms, really FUCKING BIG and dangerous GRBs tend to be tightly focused given the inverse square law.
It's highly unlikely that a ship gets hit by a GRB.
On the other hand, general radiation gets worse the faster you go, so you need shielding either way. All you have to do is line the walls of your ship with a shit ton of water, which can be mined in space.
I'm reminded of the joke that the most dangerous thing in the ocean is all the water.
We don't have fuel sources that can run long enough for the trip, and deep space won't have enough solar radiation. We would need reliable mining spots along the way to replace metals made brittle by exposure or punctured by micro asteroids.
Even travelling at 1% the speed of light, stray hydrogen atoms become a problem. Not counting acceleration or deceleration time, that would be over 400 years just to get to the nearest star, let alone one with a habitable planet.
Can you really mine water in interstellar space, how? there’s not that many asteroids just floating out there, I think.
Maybe the previous poster was referring to the Kuiper Belt and/or the Oort Cloud? There's certainly plenty of water ice out there, with no particularly deep gravity wells to worry about.
Collecting it while usefully en route to another star system seems like it would be tricky from a delta-v perspective, but maybe the solution is to:
1) build a small worldship from an appropriate asteroid 2) fill your internal ocean in the outer solar system over the course of a generation or three 3) dive back down the gravity well for a gravitational assist from the Sun as you head to your interstellar destination 4) en route, slowly use part of your ocean as propellant, while living inside the rest of it as shielding
What is a GRB?
Gamma Ray Burst
https://en.wikipedia.org/wiki/Gamma-ray_burst :
> (GRBs) are extremely energetic events occurring in distant galaxies that represent the brightest and most powerful class of explosion in the Universe.
> The sources of most GRB are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime)[11] and extremely rare (a few per galaxy per million years).
> All in all, a GRB within a few kiloparsecs, with its energy directed towards Earth, will mostly damage life by raising the UV levels during the burst itself and for a few years thereafter.
I'm guessing without an atmosphere protecting a ship it'd be a bit worse? But it's like winning a very bad lottery to get hit by one. I guess if you're traveling thousands of years in deep sleep odds get higher?
Gamma-ray burst
The solution to this problem is straightforward, isn't it? Just add mass. Propulsion is the technological bottleneck.
It wouldn’t be that fun to live on one. The article says picture paradise, but we’re talking about potentially 1.5-2g with a dense atmosphere; we’d feel terrible all the time. Also whatever biology is in that planet is probably not compatible with us; we likely wouldn’t be able to eat it. Finally once you land, you’re screwed and stuck there. Traditional chemical propellants barely work for our planet, we’d need new ways of taking off for higher escape velocities.
>given what we know about physics at the present?
No.
My hypothesis has always been, hey, have enough kids out there, and sooner or later, they'll learn enough about the physical sciences to at least explore far away worlds. (If not go there in person.)
But yeah, expecting we can get there with what we currently know is a bit naive. We need to, <gasp>, horror of horrors, fund more research.
Space is really big. We might be able to get a probe someplace, but can't get data back. We don't even have the ability to detect a civilization as advanced as us at the nearest star (only 4 light years away, but probably can't support life as we know it) if they put all their resources into sending us a message, and we spend all our resources to look at the right moment.
There are laws of radio propagation that mean I doubt we ever will.
In turn this means a probe needs to get there, and then come back. That is a lot of energy...
I can't say it is impossible, but it is highly unlikely the laws of physics will ever give us a loop hole big enough to pull this off.
Any anthropic observation requires merely a satisficing condition, which generally means that most requisite conditions are not optimal, including consciousness :)
I mean, could be!
But also irrelevant.
note that Musk, DOGE et al has completely defunded the Habitable Worlds Observatory Space Telescope
it was slated for 2040 as the successor to Roman Space Telescope
now that will never happen, at least not my lifetime
HWO would be able to directly image worlds the size of earth
(Roman cannot, only massive uninhabitable planets)
ps. just ONE day of the Iran War would have completely funded HWO
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my brother in Christ I just barely read the title
And you'd better be fucking thankful you were allowed even that much, you filthy pleb.