Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

forbes.com

Post reply on HN
Print view View original

81–90 of 182 posts

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

#81

Post by mhandley »

bencollier49 wrote: post #45
King-Aaron wrote: post #42

Earlier quoted context omitted.

Because it just so happens that Forbes has an article about astronomy.

Yes, but it's probably rubbish clickbait. They locked me out of the site when I opted out of tracking. Good riddance and I look forward to their receiving a hefty fine from the EU for GDPR non-compliance.

Yes, I had the same issue. Selected just the minimal cookies they said they needed to run the site. Site makes you way several minutes while the "process your request". Then got locked out. Oh well, another site I can live without, but I too look forward to them getting a fine from the EU.

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

#82

Post by neuronic »

quietbritishjim wrote: post #77
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…

> life appeared so soon after the Earth became solid It took hundreds of millions of years, possibly up to a billion years, for basic life to form on Earth. I would say that is not "soon"; it's a really long time . The obvious response to that is, yes it seems like a long time, but it's not much on geological time scales. But it feels to me that there's an implicit circular argument here: the whole reason that geolog…

But that's mostly because humans aren't an achievement of "life". We were never a development goal of "life" nor does the universe care very much about us - even if we built megastructures directly harnessing the energy of black holes and stars.

If current knowledge is remotely correct, heat death will happen, no matter how immortal Homo deus will become. The quarks are against us.

And if complex systems theory teaches us anything then it would be preposterous to assume any ultimate superiority in understanding the universe on our part.

Who knows who wrote crazy alien versions of Hacker News posts 2 billion years ago in one of the other couple of thousands of galaxies seen in Hubble Deep Field alone...

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

#84

Post by quietbritishjim »

neuronic wrote: post #82
quietbritishjim wrote: post #77

Earlier quoted context omitted.

> life appeared so soon after the Earth became solid It took hundreds of millions of years, possibly up to a billion years, for basic life to form on Earth. I would say that is not "soon"; it's a really long time . The obvious response to that is, yes it seems like a long time, but it's not much on geological time scales. But it feels to me that there's an implicit circular argument here: the whole reason that geolog…

But that's mostly because humans aren't an achievement of "life". We were never a development goal of "life" nor does the universe care very much about us - even if we built megastructures directly harnessing the energy of black holes and stars. If current knowledge is remotely correct, heat death will happen, no matter how immortal Homo deus will become. The quarks are against us. And if complex systems theory teach…

Humans are really just an example, I regret mentioning it. All significant developments in life (e.g. multi-cellular lifeforms, post-Cumbrian explosian animals) took hundreds of millions to billions of years.

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

#85

Post by Retric »

zaarn wrote: post #73
kamaal wrote: post #72

Earlier quoted context omitted.

I thought black holes typically have accretion disk.

Only when active and sucking in matter. If a black hole has been travelling without eating for long enough the accretion disk can disappear. If a black hole is large enough it won't form an accretion disk either as it swallows stars whole.

You can still detect the bent light around it from other stars. They would be significantly more obvious than planets, and you would actually reflect a tiny fraction of radar as it gets bent around the thing.

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

#86

Post by Retric »

boznz wrote: post #59
mrarjen wrote: post #53

Earlier quoted context omitted.

Exactly, and I saw that when the Andromeda Galaxy collides with ours, it's unlikely many planets/systems will be colliding with one another.

Never really understood how galaxies can collide if space has been expanding since the big bang and everything is moving apart

On very large scales gravity collected mater into what look like spider webs, with vast amounts of empty space and threads of interstellar gass which can form galaxies. Those galaxies form little clumps within those threads with gravity causing them to orbit each other. However, as it's a many body problem things are not stable over very long time frames and galaxies often hit each other. This does slow down over time as there are fewer remaining galaxies in a cluster.

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

#87

Post by zeth___ »

quietbritishjim wrote: post #77
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…

> life appeared so soon after the Earth became solid It took hundreds of millions of years, possibly up to a billion years, for basic life to form on Earth. I would say that is not "soon"; it's a really long time . The obvious response to that is, yes it seems like a long time, but it's not much on geological time scales. But it feels to me that there's an implicit circular argument here: the whole reason that geolog…

Life shows up in the fossil record more or less as soon as rocks on the Earths surface start forming.

The first billions years on earth mostly involved the planet getting hit by large things and the surface melting. Repeat every millennium.

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

#88

Post by cobbzilla »

ben_w wrote: post #69
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.

The extra mass of the planet would increase the rate of fusion. https://what-if.xkcd.com/14/

to a point you are right, but clearly there is some boundary, right? imagine a solid object with a mass just below the Chandrasekhar limit and a temperature near absolute zero. Don't tell me hurtling that into the Sun will make it burn hotter. And even if it would (or a smaller object) in the long run, there would at least be some period of time before the incoming matter reached fusionable temperatures, reducing power output in the short term.

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

#89

Post by varjag »

nabla9 wrote: post #41
lev99 wrote: post #32

Earlier quoted context omitted.

The article states that planets may outnumber stars 100,000 to 1. The Milky Way has 4E^11 stars. It has an upper estimate of 4E^16 planets. It has a lowest estimate diameter of 100kly. It has an estimated thickness of 2kly. It's lower estimate volume is 63,000 kly^2. ----------------------------- If planets are uniformly disrupted (they surely aren't), there are ~17 planets in every cubic light year. Sure, that's a h…

> ~17 planets in every cubic light year. The change of hitting one while traveling one light year is in the order of 10e-16.

About the same as getting shot while drowning in bathtub stricken by lightning?

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

#90

Post by DoctorOetker »

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...

you mean well before the big bang: e^(a*t) = 0 for t=-infinity
Post reply on HN