Two potentially life-friendly planets found orbiting a nearby star • Hacker News Board

Re: Two potentially life-friendly planets found orbiting a nearby star

#181

Post by btouellette » Tue, Jun 18, 2019, 5:10 PM UTC

Eupolemos wrote: post #135

petercooper wrote: post #20

"just 12 light-years away" I love the "just". I know it's nearby on galactic scales but it's practically about 450,000 Earth years away with current technology :-)

I think current technology makes no sense when talking about interstellar travel. I wonder how long it'd take, seen from the perspective of the ship, if we had an engine capable of delivering a constant 1g acceleration. That's the way we'll want to travel, after all.

Lot of details relevant to this question here: http://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/r...

Re: Two potentially life-friendly planets found orbiting a nearby star

#182

Post by Someone » Tue, Jun 18, 2019, 5:12 PM UTC

superpermutat0r wrote: post #145

Eupolemos wrote: post #135

Earlier quoted context omitted.

I think current technology makes no sense when talking about interstellar travel. I wonder how long it'd take, seen from the perspective of the ship, if we had an engine capable of delivering a constant 1g acceleration. That's the way we'll want to travel, after all.

constant 1g acceleration gets you to speed of light pretty quickly (around 1 year), so still around 12 years.

If our current ideas about physics are correct, acceleration _never_ gets you to speed of light.

The faster you go, the higher your relativistic mass, so if you accelerate by constant force, the lower your acceleration. Conversely, to keep acceleration constant, you would need larger and larger forces, in the limit ‘infinite force’.

For more and better info, see https://en.wikipedia.org/wiki/Space_travel_using_constant_ac....

Re: Two potentially life-friendly planets found orbiting a nearby star

#183

Post by r00fus » Tue, Jun 18, 2019, 5:14 PM UTC

psychometry wrote: post #162

cjbprime wrote: post #155

The trilogy _Three Body Problem_ is a good read, and has something to say about this. :)

I had high hopes, but TBP is a terrible novel. It certainly has some fascinating ideas, but just as many ludicrous ones that are equally central to the plot. Not to mention Liu is absolutely terrible at anything relating to characters: dialogue, character development, etc.

I agree - I read the trilogy and enjoyed it somewhat but I wouldn't recommend it to others (unlike e.g. Hyperion Cantos or Fire Upon the Deep, etc).

The amount of suspension of disbelief for some questionable premises is very high. e.g. the real-time comms developed by one of the races breaks down one of the key axioms.

Re: Two potentially life-friendly planets found orbiting a nearby star

#184

Post by r00fus » Tue, Jun 18, 2019, 5:19 PM UTC

techdragon wrote: post #112

DCKing wrote: post #84

Earlier quoted context omitted.

The Orion program had this potential on paper. Nuclear bomb propulsion is a complicated thing, but we don't understand if it's a feasible propulsion method in practice, like, at all . Political will in this case brings us more understanding of the feasibility of this propulsion method, but it's way too big of a stretch that political will alone would get us to the nearest starts in 200 years.

Actually we do know it would work. The fundamental physics are sound. A pusher plate can in fact transfer net positive momentum from a series of explosive shockwaves detonated aft of the pusher plate in the desired direction of travel. There’s plenty of video footage from the Hot Rod tests showing it working. https://youtu.be/Q8Sv5y6iHUM The hot rod test article was actually donated to the national air and space muse…

The propulsion could work. What about sustaining life for 200 year biospehere without any external resources?

What about interstellar debris?

What about deceleration?

And that's just the feasibility of the colony ship, then there's colonization/terraforming, etc.

I'd be thrilled to see such an effort take shape, but to say "it would work" has marginal relevance to "the project is feasible".

Re: Two potentially life-friendly planets found orbiting a nearby star

#185

Post by umeshunni » Tue, Jun 18, 2019, 5:22 PM UTC

Wouldn't planets orbiting this close to the star be tidally locked to it? If they are tidally locked to the star, they are also likely to have extreme temperature variations between the two sides. This could rule out life.

Re: Two potentially life-friendly planets found orbiting a nearby star

#186

Post by r00fus » Tue, Jun 18, 2019, 5:23 PM UTC

corodra wrote: post #100

onemoresoop wrote: post #62

Earlier quoted context omitted.

And imagine you're the first ship to arrive only to find out a) that the planet is not habitable and there were some wrong assumptions about it b) that the planet is already occupied by a different form of life and there's no warm welcome to us

This is also assuming A) Human engineering can create something that can last 200+ years of space travel. We don't even build houses anymore that can feasibly last 100 years. 2) People don't go mad and kill each other or do a mutiny III) Any number of stray objects from asteroids to rogue planets that just slams into the ship and causes major malfunctions d) Food and life support sustainability I mean... there are SO…

The crazy ones are the ones that change the world/universe. For the right price, it would make sense to invest in such a venture.

Re: Two potentially life-friendly planets found orbiting a nearby star

#187

Post by slg » Tue, Jun 18, 2019, 5:27 PM UTC

SantalBlush wrote: post #168

XorNot wrote: post #107

The note that it's an old star makes me worry though. If they're older then us, and habitable, were they inhabited? Our current era is a few hundred years of real, directed technological development. A few thousands years either side of that and who knows what we'd be looking at, but you imagine that - hopefully - the general progression of technology is forward. So if they were inhabited, what happened to them? Are…

Do we know that intelligent life is an evolutionary inevitability? Most of these discussions seem to assume that it is, but I haven't read any biologists mention this.

Or to take it a step further, whether it is inevitable that intelligent life will have both the capability and opportunity to make their presence known. Maybe some planets are full of superintelligent dolphin-like creatures that had their development stall because they didn't have the dexterity to manipulate tools to the extent that sapiens can. Or maybe there is intelligent life on a planet similar to Europa that never prioritized space exploration/communication because instead of an Earthlike atmosphere their planet is surrounded by miles of ice.

Re: Two potentially life-friendly planets found orbiting a nearby star

#188

Post by pdonis » Tue, Jun 18, 2019, 5:28 PM UTC

Someone wrote: post #182

superpermutat0r wrote: post #145

Earlier quoted context omitted.

constant 1g acceleration gets you to speed of light pretty quickly (around 1 year), so still around 12 years.

If our current ideas about physics are correct, acceleration _never_ gets you to speed of light. The faster you go, the higher your relativistic mass, so if you accelerate by constant force, the lower your acceleration. Conversely, to keep acceleration constant, you would need larger and larger forces, in the limit ‘infinite force’. For more and better info, see https://en.wikipedia.org/wiki/Space_travel_using_consta…

> The faster you go, the higher your relativistic mass, so if you accelerate by constant force, the lower your acceleration.

The Wikipedia article you linked to calls this (rightly) a "half-myth". It depends on your reference frame.

Re: Two potentially life-friendly planets found orbiting a nearby star

#189

Post by MR4D » Tue, Jun 18, 2019, 5:31 PM UTC

dunkmaster wrote: post #123

MR4D wrote: post #109

Earlier quoted context omitted.

> Only 12ly away and that one has maybe two habitable planets? That tells me the universe is teaming with potential homes for life. This seems like the birthday problem in statistics [0] - that if you have 30 people, it's likely that two people have the same birthday. However, the problem that could also exist (in our corner of the galaxy) that everyone else has a birthday far away from ours, and nobody else shares a…

The birthday paradox works because you are looking for a pair that has the same birthday, regardless of what date that birthday is. It doesn't work in the habitable planet sense because you would be essentially locking the birthday to a fixed date.

I'm locking the area to a specific region. If I divide the universe into 365 discrete areas, the problem is exactly the same.

Re: Two potentially life-friendly planets found orbiting a nearby star

#190

Post by caymanjim » Tue, Jun 18, 2019, 5:33 PM UTC

XorNot wrote: post #107

The note that it's an old star makes me worry though. If they're older then us, and habitable, were they inhabited? Our current era is a few hundred years of real, directed technological development. A few thousands years either side of that and who knows what we'd be looking at, but you imagine that - hopefully - the general progression of technology is forward. So if they were inhabited, what happened to them? Are…

> So if they were inhabited, what happened to them? Are they exactly at our level of development? Earlier? Hopefully. Because later poses some real big questions - does technology top out about where we are now - no FTL travel, no really big radio transmitters or stellar engineering? No probes to nearby star systems? Did they even make it past the nuclear age, or avoid wrecking their climate?

You get more than one chance. While finding intelligent life would be great, finding any life is nearly as great. We might not catch them at a comparable technological moment, but over 8 billion years, intelligent life could have come and gone many times. All we need are some biosignatures to confirm that something's out there, and exploration will kick into overdrive.