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Space Is Full of Planets, and Most of Them Don't Even Have Stars

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Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#171

Post by restalis »

ChuckMcM wrote: post #166
cobbzilla wrote: post #60

Earlier quoted context omitted.

Let's say the rogue planet is a massive, super-cold planet. How big and how cold would it have to be to lower the Sun's energy output just enough to trigger a "Snowball Earth" scenario? Assume a direct hit.

I think the only way this works is if the planet doesn't hit the Sun. One could imagine a scenario (but the orbital mechanics don't work out) where a massive rogue planet enters into the solar system and interposes itself between the Earth and Sun, thus shading the Earth and dropping its temperature the required amount. Sort of like a month long solar eclipse or something. But at that mass it's probably pulling Earth…

"where a massive rogue planet enters into the solar system and interposes itself between the Earth and Sun, thus shading the Earth and dropping its temperature the required amount. Sort of like a month long solar eclipse"

For our planet's distance from the sun, I have a hard time imagining how anything without self propulsion could maintain a stable orbital position to cast a shade over us for a long enough period (e.g. a month).

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#172

Post by gmiller123456 »

ASalazarMX wrote: post #161
tiemand wrote: post #146

Earlier quoted context omitted.

One problem I have with pan-spermia is: Why is there only one tree of life? Not several independent trees. If life evolved in one of the exo-planets, is not possible that several independent forms of life evolved in several planets and some ended up on Earth.

I also don't subscribe to panspermia because first local origin must be reasonably proved unfeasible, but playing devil's advocate ¿what if our life tree outcompeted the others?

That's certainly possible, but not likely. Life began on Earth almost as soon as it was cool enough to do so, so we would expect to see life pop up over and over again. And it's highly unlikely that they would all get wiped out.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#173

Post by dc443 »

qubex wrote: post #27
ChuckMcM wrote: post #20

Earlier quoted context omitted.

Napkin math (aka pure speculation) suggests that unless the rogue planet hit the star directly and at an angle that could send ejecta our way, the results would be more observational than catastrophic. The Earth is roughly 333,000 times less massive than the Sun. Think of it this way, If an asteroid hit the Earth that was, in relative terms, the size of the earth relative to the sun, it would be about 1/3 the size of…

Thumbs up for Coronal Breaking Manoeuvre !

the word is spelled "brake"

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#174

Post by dc443 »

cobbzilla wrote: post #162
sudhirj wrote: post #94

Earlier quoted context omitted.

Seems unlikely for fusion. Think of it from the point of view of star formation - the gas that coalesces into a ball is already super cold from floating around in space. The heat for fusion comes from gravity compressing the matter, not from the starting heat energy present in the matter itself. So yeah, you can't really add cold stuff to starts to extinguish them - stars are made from absolute ice to being with.

wow. i had never thought of it like that. thank you.

ya, the steady-state temp of a star is a byproduct of its fusion process, which is directly controlled by the pressure of gravity. More mass, more gravity... the kinetic energy of the temperature of that mass pales in comparison to the E=mc^2 energy contained in that mass.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#175

Post by perl4ever »

hyperpallium wrote: post #75
perl4ever wrote: post #19

Based on the inverse correlation between star size and frequency, this doesn't surprise me at all. It seems like there is an obvious further inference to make - people have debated whether life originated on earth or not. Given that the vast majority of planets do not have a star, and given that we know there are chemotrophs even on Earth that prove it is possible to live without a sun, it seems overwhelmingly likely…

If you're a fan of Moore's Law and the Singularity, you'll love the reasoning of backtrapolating the exponentially increasing complexity of life over time... to get 0 well before the formation of the earth https://www.technologyreview.com/s/513781/moores-law-and-the...

That's exactly why I was on the side of panspermia already. But the number of rogue planets makes a nice independent path to the same conclusion.

An interesting question to me is - if the Earth was seeded with life, does this mean we will find life elsewhere in the solar system, because they were too, or does it mean we will not find life elsewhere, because a rogue planet collided with proto earth in a very unlikely event, and the rest of the solar system (or at least the potential life supporting objects) came out of a sterile nebula around the sun?

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#176

Post by vorg »

antisthenes wrote: post #147
vorg wrote: post #124

Earlier quoted context omitted.

> At near lightspeed, a pea-sized rock will kill your spaceship Why travel in a spaceship? If there's 100,000 starless planets for every star in the galaxy, then travel between stars on one of them instead. Build the habitations 10 km below water to avoid radiation. Travel at 0.1% light speed instead and get to the nearest star in 5000 yrs. Enjoy the journey, and slip into an orbit around the target star. Speaking of…

Powered by what?

The planets will already be moving when captured. Mine them for energy and make adjustments to their trajectory so they'll enter into an orbit in the target star system. Drill a hole through the center for firing the pea-sized bullets. Using the recon from the bullets, find out more about the gravitational state of the star system and make small early adjustments to your own trajectory to compensate.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#177

Post by vorg »

restalis wrote: post #169
vorg wrote: post #124

Earlier quoted context omitted.

> At near lightspeed, a pea-sized rock will kill your spaceship Why travel in a spaceship? If there's 100,000 starless planets for every star in the galaxy, then travel between stars on one of them instead. Build the habitations 10 km below water to avoid radiation. Travel at 0.1% light speed instead and get to the nearest star in 5000 yrs. Enjoy the journey, and slip into an orbit around the target star. Speaking of…

"periodically fire one laden [rock] with electronics/optics/quantumics at the target star at near light speed and receive its transmissions for recon" These would act as space weather beacons, forming some kind of illuminated space (high)way. An interesting idea! As for the rogue planets, although I envision humans having some use for them, I doubt it will be for interstellar travel the way you describe.

If it's impossible for humans to move between stars in tiny capsules, then capturing rogue planets may be the only option.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#178

Post by hyperpallium »

whatshisface wrote: post #148
hyperpallium wrote: post #97

Earlier quoted context omitted.

well yes; technically they use one base-pair as the origin of life (which is probably still a little too small). From looking at the graph, and the 300 milion year doubling, they seem to put life complexity at about 256 base-pairs at the origin of the earth. There should be a link to the actual paper in the article.

That goes below a discontinuity, 256 base pairs is well below the smallest organism ever observed. A single gene is on average around 10^4 bases, and the simplest organisms have around 10^3 necessary genes. Life below 10^3 base pairs may not evolve at the same speed. It's certainly not safe to talk about it in terms of base pairs, in that era there might not have even been any.

> smallest organism ever observed

...today. Life was simpler back in the day. For example, RNA world. This more primitive life might not survive more sophisticated life. (thougn it's also possible it's still around, but we haven't noticed it; or haven't recognized it as life).

IDK if small enough, but viruses are simpler.

If it can reproduce - e.g. a short strand of DNA or RNA or even something simpler - it could form the beginnings of "life" as a precursor, even though it wouldn't meet our current definitions of "alive".

There's theories of fatty spheres being the first "cells" (really, "kinda sorta cells").

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#179

Post by hyperpallium »

pavlov wrote: post #113
Aaargh20318 wrote: post #102

Earlier quoted context omitted.

Personally I think the answer is anti-natalism. Once life gets more intelligent it takes a relatively short time (compared to the age of the universe) to get to the point where they realise it's unethical to create new life and choose to go extinct. As a result, intelligent life around the universe only exists as short 'blips', being around for too short a time to ever meet other species.

The default for unintelligent life is to survive at all cost and fill every niche. You're suggesting that intelligence flips that purpose so that every sentient species eventually becomes depressed suicidal existentialists?

I'd put it even stronger, especially in this context where we contemplate radically simpler origins of life, that mightn't be "alive" by standard definitions (like viruses), and yet are steps along the way to sufficient complexity to be "alive": that life (in this context) is reproduction.

Re: Space Is Full of Planets, and Most of Them Don't Even Have Stars

#180

Post by ripsawridge »

throwaway7312 wrote: post #112
m_mueller wrote: post #91

Earlier quoted context omitted.

What about Fermi's paradox though? I mean, where is everyone?

Uncontacted tribes in the Amazon likely wonder the same thing. It's such a big Earth, yet only a few hundred humans are known to exist. Why are there no other detectable signs of human life, like smoke signals, territory markers, or emissaries from any more but a handful of other tribes? Surely if advanced humans existed, they would have contacted these tribes by now, to share technology, discoveries, and medicine. Y…

Uncontacted tribes in the Amazon are not really uncontacted. They are the way they are by preference.
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