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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

#211

Post by dheera »

joshuahedlund wrote: post #124
SEJeff wrote: post #119

Earlier quoted context omitted.

Or aren't primarily carbon based whatsoever.

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?

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

#212

Post by dheera »

neaden wrote: post #169
dheera wrote: post #110

Earlier quoted context omitted.

Meh. 200 years aro they would have called you insane for wanting to fly between continents, let alone to the moon.

They also would have called you crazy for saying you wanted to turn lead into gold with alchemy. Fact is, most of the time the people who say something can't be done are right.

Yeah but they don't matter. All the trying was worth it, because I can fly halfway around the Earth for a few hundred bucks now. If in a different world I got gold out of lead but no airplanes, it would be fun too, but in a different way.

If the no-sayers really won and nobody tried, we would have neither.

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

#213

Post by bdamm »

joshlegs wrote: post #200
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 :-)

there is an effort to put super mini spaceships on missions to other solar systems, and they would travel at something like 20% the speed of light. I think it works by having the probes be like the size of a cellphone or something, and being attached to a solar sail, then using an incredibly high powered laser to pump the solar sail full of energy to get it going so fast. I think if that architecture works they could…

However, a transmitter with enough power to signal earth would be too massive to get fast with a solar sail, given today's technology. Maybe a chipsat gets to 20% c, but no way a dish does.

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

#214

Post by CWuestefeld »

hesk wrote: post #207
CWuestefeld wrote: post #192

I saw a study recently, unfortunately I can't locate it now. It discussed the possibility of there having been past civilizations on Earth, hundreds of millions or even billions of years ago. The conclusion was that this can't be entirely ruled out. It noted how few actual fossil remains we have for what we know of dinosaurs, and that there's a lot of space left in those gaps for all the evidence to have been destroy…

Maybe it was this? Gavin A. Schmidt, Adam Frank: The Silurian Hypothesis: Would it be possible to detect an industrial civilization in the geological record?, https://arxiv.org/abs/1804.03748 I found it through an article in The Atlantic that may or may not have been linked on HN recently. https://www.theatlantic.com/science/archive/2018/04/are-we-e...

Yes, I believe that was it. Thanks!

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

#215

Post by TheOtherHobbes »

caymanjim wrote: post #199
CWuestefeld wrote: post #192

I saw a study recently, unfortunately I can't locate it now. It discussed the possibility of there having been past civilizations on Earth, hundreds of millions or even billions of years ago. The conclusion was that this can't be entirely ruled out. It noted how few actual fossil remains we have for what we know of dinosaurs, and that there's a lot of space left in those gaps for all the evidence to have been destroy…

It's incredibly improbable. While much of the planet's surface is recycled constantly, there are also huge swaths of land that are billions of years old and haven't changed enough to hide evidence of complex society. Dinosaur fossils are rare, but not that rare. Tiny ones are abundant. If all life on earth ceased today, you could come back here in a billion years and find plenty of evidence everywhere. Maybe it's not…

I like to entertain a mad fringe theory that the K-Pg asteroid was a war weapon.

You might think no species would be insane enough to consider bombing its own planet to the point of extinction-level oblivion, but - that doesn't appear to be true.

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

#216

Post by Tepix »

There was a paper recently that argued that the habitable zone is smaller than anticipated because either the concentration of carbon dioxide will be too high (and thus toxic at least to life on Earth) or - for small stars like this - there will be (toxic) carbon monoxide in the atmosphere.

https://phys.org/news/2019-03-complex-life-require-narrow-ha... (good article with link to the paper)

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

#217

Post by WhompingWindows »

jzawodn wrote: post #121
_Kristijan_ wrote: post #59

Feels like we're playing the first round in "Master of Orion" when you start scanning the stars around you ;)

I still love that game.

I remember around 2003, making huge battleships in that game and squaring up against the AI's armada. The AI made about 500 tiny ships with weapons incapable of breaching my shields, and with their own shields incapable of surviving my dreadnought blasts. I would kill 5 with my big ships, take no damage from 495 shots, rinse and repeat. The battles took hours! I had to skip tactical battles, couldn't stand that much time, just had the AI simulate it.

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

#218

Post by dunkmaster »

MR4D wrote: post #189
dunkmaster wrote: post #123

Earlier quoted context omitted.

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.

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.

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

#219

Post by joshlegs »

bdamm wrote: post #213
joshlegs wrote: post #200

Earlier quoted context omitted.

there is an effort to put super mini spaceships on missions to other solar systems, and they would travel at something like 20% the speed of light. I think it works by having the probes be like the size of a cellphone or something, and being attached to a solar sail, then using an incredibly high powered laser to pump the solar sail full of energy to get it going so fast. I think if that architecture works they could…

However, a transmitter with enough power to signal earth would be too massive to get fast with a solar sail, given today's technology. Maybe a chipsat gets to 20% c, but no way a dish does.

Found the wiki page for the project: https://en.wikipedia.org/wiki/Breakthrough_Starshot

so it looks like they'd want to launch by 2036. In the 'technical challenges' section, it does mention that some technologies would have to be miniaturized sufficiently, but it doesnt really mention much about whether that technology has reached viable stages or not, or whether it's a realm they'd have to specifically research further.

So I guess maybe the technology doesn't exist today? Sounds like probably not, but maybe the near future -- or at least they expect it to exist by 2036.

It's worth noting this project has backing by some pretty influential folks, including Stephen Hawking when he was still alive.

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

#220

Post by nurettin »

api wrote: post #78
simonh wrote: post #77

Earlier quoted context omitted.

>Orion is a fabulous and quite valid counter to the folks that seem to like to repeat the canard that interstellar flight is impossible. I’d never say it’s impossible, if we maintain a civilisation for long enough it might even be inevitable at least at a minimal level. However, Daedalus/Orion is far from as straightforward as has been suggested by you and others. It’s based on projections of technology made in the 7…

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.
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