Yet another Hacker News

Worlds More Habitable Than Earth? They're Out There

27 points cainxinth 4 hours ago 28 comments

PorciiVorbesc 1 hour ago | parent

We just need to find where The Ancients buried the Stargate on Earth. Let's gooo!

vintagedave 25 minutes ago | parent

Good news! https://news.ycombinator.com/item?id=50067414

ubermonkey 1 hour ago | parent

I mean, could be!

But also irrelevant.

freecodeio 58 minutes ago | parent

> Thanks for reading The Times.

> Create your free account or log in to continue reading.

my brother in Christ I just barely read the title

fred_is_fred 52 minutes ago | parent

Is there any plausible way for a human to ever reach one given what we know about physics at the present?

imzadi 47 minutes ago | parent

Generation ships with plasma sails, probably.

bilbo0s 44 minutes ago | parent

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.

unrented7977 38 minutes ago | parent

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.

cdelsolar 28 minutes ago | parent

Can you really mine water in interstellar space, how? there’s not that many asteroids just floating out there, I think.

GolfPopper 12 minutes ago | parent

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

zdragnar 21 minutes ago | parent

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.

marcusverus 31 minutes ago | parent

The solution to this problem is straightforward, isn't it? Just add mass. Propulsion is the technological bottleneck.

mrnotcrazy 29 minutes ago | parent

What is a GRB?

marricks 24 minutes ago | parent

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?

philk10 23 minutes ago | parent

Gamma-ray burst

bilbo0s 46 minutes ago | parent

>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.

bluGill 27 minutes ago | parent

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.

unrented7977 35 minutes ago | parent

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.

stouset 19 minutes ago | parent

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.

Scarblac 13 minutes ago | parent

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?

stouset 10 minutes ago | parent

Yeah, I added that I think around the time you replied :)

stymaar 17 minutes ago | parent

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.

cdelsolar 22 minutes ago | parent

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.

Jtarii 5 minutes ago | parent

We are at least 1000 years away from being anywhere close to this.

catigula 23 minutes ago | parent

Any anthropic observation requires merely a satisficing condition, which generally means that most requisite conditions are not optimal, including consciousness :)

joe_the_user 16 minutes ago | parent

https://archive.is/yIYpb