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Two potentially life-friendly planets found orbiting a nearby star

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

#291

Post by flyingfences »

stcredzero wrote: post #160
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…

The note that it's an old star makes me worry though. If they're older than us, and habitable, were they inhabited? Many dwarf stars have more solar flares than our sun, while their planets are closer. Teegarden's star is supposed to be very calm right now. I have no idea if that is likely to be true over most of the past 8 billion years. The amount of water they gather may be smaller, and their closer planets may no…

> Since most of the star's energy is emitted in the infrared ... does this limit the potential of photosynthetic organisms ... ?

I'm not any sort of biologist or chemist, so somebody please correct me if I'm wrong, but...

If you specifically meant photosynthesis by terran chlorophyll, then yes, I suppose it would be less effective. However, I could imagine photosynthetic life to evolve under those conditions that uses some other compound to capture and convert the energy.

Also to consider is the amount of radiation (light, etc.) available on the surface, which can be figured as a formula of the radiation emitted by the sun, distance from the sun to the planet, and attenuation of radiation by the atmosphere. Much of the light (and other energy) emitted by a sun does not reach the surface of a planet with an atmosphere. The particulars are, of course, dependent on the atmospheric composition, but generally I would expect infrared light, with longer wavelengths than visible light, to better penetrate the atmosphere and be more available to life on the surface.

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

#292

Post by blotter_paper »

jl6 wrote: post #266
MRD85 wrote: post #263

Earlier quoted context omitted.

Imagine an easy mode planet in a system with multiple habitable planets. Now that I've typed that I'm also considering how Mars would look from 12 light years away. Is establishing a colony 12 light years away easier than transforming mars into a habitable planet?

Harder, I think. We have the technology to live on Mars (not to terraform it, just to survive on it). We have some ideas from physics about how to get to a planet 12 ly away, but not the technology. Nor, I would argue, do we have the social and political setup required for such a project, which would most likely take hundreds of years to get to a basic colony.

> We have the technology to live on Mars (not to terraform it, just to survive on it).

I'm not convinced this is true intergenerationally without a maternity ward in a centrifuge; the low gravity mouse embryo experiments don't look promising. Maybe 1/3rd earth gravity is enough, but I'm doubtful. If we're granting centrifugal habitats as something doable with current technology, an Orion/Daedalus style nuke-propelled spacecraft seems in the same ballpark. It's been sketched out and tested with models, it's clearly possible, but nobody has really made one yet and it's a hell of an engineering problem still.

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

#293

Post by loteck »

gameswithgo wrote: post #134
sametmax wrote: post #96

Earlier quoted context omitted.

I smiled as well but with a slowly but steadily accelerating ship we can reach half the light speed and get there in 50 years. It put things in the realm of "possible" which is amazing.

now do some napkin math on the reaction mass and energy you need to slowly accelerate that much for that long

don't forget, you're going to have to slow down at some point, too

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

#294

Post by hakanito »

m3kw9 wrote: post #280

What I’m interested in is if somehow there is a planet almost exactly like earth, if so would they have evolved humans similar to us.

I too like this thought experiment! Checkout the movie Kpax with Kevin Spacey if you haven’t already, it touches on the subject — ”Why is a soap bubble round? It’s the most efficient form”

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

#295

Post by owenversteeg »

dheera wrote: post #211
joshuahedlund wrote: post #124

Earlier quoted context omitted.

I highly recommend the book The Equations of Life: How Physics Shapes Evolution[0] . While it's be foolhardy to rule out other dramatically different forms of life, there are only so many candidates in the periodic table and only so many of those in common concentrations throughout the universe. The universal laws of physics that continually converge on the same solutions on Earth, and the fact that life has apparent…

Why does life have to be chemical as we know it? Why can't a massive galactic-scale lifeform exist upon gravitational waves, radioactive particles, or even dark matter or things we don't know?

I agree with your general idea, that perhaps life exists in non-chemical ways, but a galactic scale life form would be tricky for a ton of reasons - just one would be inter-organism communication.

The Milky Way is a pretty average galaxy and it's 100,000 light years in diameter. In humans, if inter-hemispheric signals takes 3ms you can achieve roughly 40hz "synchronic activity". Let's say (and this is a massive simplification) that the inverse of the maximum inter-brain delay is ten times the "clock speed" of the brain. That would give a human that lives 80 years over 100 billion clock cycles in a life, and a galactic brain that communicates at light speed (so 3e-13 hz "clock speed") only 9467 clock cycles in 1 billion years.

So one single human life would have ten million times more "clock cycles" than a billion years of this galactic life-form existing. Or, the galactic life form would have about 3 minutes and 55 seconds worth of "normal" human thought, from the moment it's born until one billion years later. I know human babies certainly don't do a lot in their first 3 minutes and 55 seconds.

Or, for a simpler example: say a massive star goes supernova at one end of the "brain", damaging it and requiring resources from the other side. It'll be a minimum of 200,000 years before that section gets repaired.

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

#296

Post by Dylan16807 »

nurettin wrote: post #220
api wrote: post #78

Earlier quoted context omitted.

Not Daedalus, Orion. It was a 1960s research project involving Freeman Dyson and others. Google it. There is a fantastic documentary that I think is on YouTube. Orion is kind of shockingly practical. It was forgotten for some time as it was a military research project not NASA or academic.

Do you acknowledge the fact that interstellar travel entails more than just speeding up and slowing down? Because that's what Dyson would be telling you if he were here.

You need a nuclear-powered airtight bunker that can sustain dozens of people, but that's also buildable with 70s technology.

Once you have propulsion and a ship you're pretty well there.

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

#297

Post by carapace »

ohaideredevs wrote: post #204
r00fus wrote: post #183

Earlier quoted context omitted.

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.

I read TBP and A Deepness in the Sky at the same time. Despite the "big ideas", TBP isn't even in the same league. Can't bring myself to read the second TBP book, just don't care. Did buy a Fire Upon a Deep recently, looking forward to it.

Vinge is a master.

"Rainbows End" is must-read cyberpunk IMO. (And of course he wrote "True Names". (In '81!))

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

#298

Post by carapace »

sametmax wrote: post #96
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 smiled as well but with a slowly but steadily accelerating ship we can reach half the light speed and get there in 50 years. It put things in the realm of "possible" which is amazing.

https://en.wikipedia.org/wiki/Torchship

> Torchship (or torch ship) is a term used by Robert A. Heinlein in several of his science fiction novels and short stories to describe fictional rocket ships that can maintain high accelerations indefinitely, thus approaching the speed of light. The term has subsequently been used by other authors to describe similar kinds of fictional spaceships.

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

#299

Post by Retra »

the8472 wrote: post #283
gambiting wrote: post #148

Earlier quoted context omitted.

I'd argue that a colony at the bottom of our own ocean would survive literally any event of any magnitude, maybe except for a direct asteroid strike. In terms of survivability of the human race, that's a better project to start with - and of course then move on to other planets, but underwater/underground colonies would give us lots of insights into living in such environments permanently.

The pressure range range between vacuum, mars atmosphere and earth atmosphere is 10⁵Pa. The pressure at the bottom of the ocean is 10⁸Pa. Humans can survive the former with little more than strong tensile garment and a breathing apparatus, the latter requires massive, crumple-resistant pressure vessels around everything.

Finally someone with the sense to realize what difference an order of magnitude can make to a decision. Now lets compute how likely we are to die by an asteroid vs how likely we are to die being stranded on a barren, frozen rock 60M Km away from the nearest source of critical supplies.

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

#300

Post by jtolmar »

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.

I don't think we even know that a planet that's had life twice as long gets twice as much evolution. The rate of evolutionary change is far from constant, and whatever factors affect that rate might be different on some other planet.
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