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Two potentially life-friendly planets found orbiting a nearby star

nationalgeographic.com

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

#241

Post by erikpukinskis »

soulofmischief wrote: post #165
joshuahedlund wrote: post #98

Earlier quoted context omitted.

Yes 12 ly is amazingly close! > If we presume there's nothing special about our little corner of the universe, then the distance to the nearest potentially habitable planets gives us an estimate of how many habitable planets are out there I would put a slight caveat to this - I would argue we do know there's something "special" about our little corner of the galaxy , at least - we are in the continuously habitable zo…

Wouldn't each system's star do a decent job of pushing back extra-solar radiation? Up to a point, obviously, but it would seem that planetary background radiation levels aren't a direct function of solar density.

Nope! Some stars are in a stable orbit in a region with some NASTY orbiting interlopers who are eating star systems every million years and have just not made their way to them yet.

We have made it at least a billion or so without getting too close to a nasty body so that says something about the region around us.

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

#242

Post by gambiting »

airstrike wrote: post #203
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.

Fair point, but then we forgo learning how to build a rocket to leave this rock should there ever be a need.

Just....do both? Have a proper, city-size, self-sustaining colony on the bottom of the ocean, and at the same time keep developing rockets and vehicles to bring as much material and and many robots over to Mars as physically possible. Like, I don't think getting to Mars is an issue - we probably could send and even land someone on Mars within a couple years if we absolutely had to. But then the question is - what then? That's the hard problem.

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

#243

Post by yellowapple »

caymanjim wrote: post #235
yellowapple wrote: post #221

Earlier quoted context omitted.

> there are also huge swaths of land that are billions of years old and haven't changed enough to hide evidence of complex society Do you have any examples? The article in the sibling comment to yours directly states that the oldest large-scale swath of land (in the Negev Desert) only dates to 1.8 million years.

That's the oldest surface land, but the oldest crust is 4.4 billion years in Australia, and there are other places with less-old-but-still-billions crust. Natural erosion in those areas exposes extensive history, and we can dig too. [1]: https://news.nationalgeographic.com/news/2014/02/140224-olde...

Surface land (current or former) is the only really relevant source of potential evidence here, though (unless we're specifically looking for subterranean civilizations, or perhaps for remains of old mines or wells).

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

#244

Post by simmanian »

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?

Life isn't something that's easy to define because literally everything exhibits patterns of life to some degree (in fact, you could definitely argue that the concept of life is an arbitrary, fictional distinction made to make our lives easier). For example, we find that cities, states, and empires look "alive" at a macroscopic level, with cars and roads forming the circulatory system to deliver much needed nutrients to far corners of the respective territories; we often give anthropomorphic characteristics to planets (Mother Earth) and stars.

When we search for life, we're probably looking for something very similar to us, something we can interact with and befriend.

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

#245

Post by roywiggins »

ithkuil wrote: post #240
dunkmaster wrote: post #218

Earlier quoted context omitted.

If you're locking the area to a fixed area out of the 365 discrete areas, the birthday paradox isn't applicable anymore. Birthday paradox only says something about whether a pair exists among all areas.

So you're in a room with N people and learn that somebody else shares your birthday. Can you conclude that is this likely that other people in the room also share the birthday with somebody else?

If you already assume the room is a representative sample from a population where birthdays are uniformly distributed, it doesn't tell you anything.

But if you aren't certain about that, it makes it less likely that everyone else with your birthday has been ritually murdered or otherwise systematically excluded from the room, and slightly more likely that you're at a convention dedicated to people with your birthday.

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

#246

Post by roywiggins »

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?

The question is, what kind of life do we know how to recognize? What kind of life definitely is possible, and what kind is just speculation? In other words: where should we look first?

The answer is: carbon rich, watery life. Coming up with biosignatures for ourselves is hard enough, coming up with a biosignature for a galactic nebula is unbelievably harder because we have no examples. Extrapolating from one example is much easier than from nothing at all.

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

#247

Post by Nelson69 »

ggggtez wrote: post #139
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 :-)

No, it's 12 years away by radio wave, which means 24 years for a round trip communication. Physical travel is out of scope, but we could share knowledge in the (extremely) unlikely case that we found intelligent life with radio technology.

If we were to realize Breakthrough Starshot, then it'd be right around the cusp of how long I'd think we could maintain institutional interest in it. 60 years to get there, 12 years to get the signals back, so 76 years. If you worked on it right out of college and longevity stays around where it is, you might live to see some pictures. You definitely could tell your grand kids about it though.

It seems technically possible, it is just a matter of paying for something like this and pinning hopes on the next generations to follow through with it and appreciate it. It seems like if we had that sort of will, climate change and some other issues would almost be non-issues.

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

#248

Post by jrjarrett »

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.

A Fire Upon the Deep is SUCH a good book. I loved it; the idea that something like the '90s net news had gone galaxy-wide was a great plot idea....

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

#249

Post by gattr »

As for interesting consequences of a vastly different planetary age: in one SF novel (could be Peter F. Hamilton's, I can't remember right now) humans colonized an Earth-like planet only some 2 billion years old or so. Its uranium ores had so high U235 content (as opposed to Earth's 0.72%, which requires costly enrichment), that you could simply smelt it and put straight in a reactor (cheap nuclear-powered locomotives anyone?).

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

#250

Post by rusanu »

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?

Evolution, because no other phenomenon can drive the required complexity to reach 'life'. Natural selection works by inheritance and mutation. Things that can create copies of themselves with mutations that allow selection to act on, this list is short.
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