Life and Death of a Planetary System | Hacker News Reader

Life and Death of a Planetary System

exoplanets.nasa.gov

73 pointshunglee227 comments

Q. Will Earth always be able to support life? A. Probably not [...] Over the next couple of billion years, the increasing amounts of energy Earth will receive from the aging, expanding Sun will warm its atmosphere.

Two billion years' work is a hefty amount in terms of scientific and technological development, assuming people survive. So, as David Deutsch would point out, what actually happens will depend on what solar engineers choose to do.

At some point it will become more economical to terraform other planets than to prevent the Earth from unterraforming.

Assuming the technology is there, we will have lots of choices available.

Maybe we can even do both.

Yes, many many choices, and it's impossible to predict what our descendants will want. Perhaps the Earth will be preserved as a monument.

> Assuming the technology is there

This is a rather large assumption to make, considering we can’t even control the environment of our own planet currently.

We are talking about two billion years! It's a possibility, in no way the only one.

It can happen that any crisis wipes us, or even life in the planet, out.

This assumes that our level of technology will increase over such long time scales. It might be cyclical, resetting to zero periodically.

Or it may flatten out as well. Without the need to reset.

We likely have much less than 2 billion years before the earth becomes uninhabitable: https://en.wikipedia.org/wiki/Timeline_of_the_far_future

The future is open. It is not predetermined and thus cannot be predicted – except by accident. The possibilities that lie in the future are infinite. When I say ‘It is our duty to remain optimists’, this includes not only the openness of the future but also that which all of us contribute to it by everything we do: we are all responsible for what the future holds in store. Thus it is our duty, not to prophesy evil, but, rather, to fight for a better world.

-- Karl Popper

Thanks for sharing the link! What a great source for procrastination :)

Loves this one for example:

15,000 yrs from now: According to the Sahara pump theory, the precession of Earth's poles will move the North African Monsoon far enough north to convert the Sahara back into a tropical climate, as it was 5,000–10,000 years ago.

They will probably be hired by a company that makes people click ads.

Sounds like a side plot from The Hitchiker's Guide to the Galaxy.

Maybe we can come up with a way to adjust the Earth-Moon system's orbit. As the sun starts to expand, the orbit gets wider with it. Sure, it'll be in the same orbit as Jupiter or something, but it's all just a stop gap until the sun goes BOOM. Don't think it'll be anything but a dead rock at that point.

The sun will not go BOOM, barring collision with another, much larger star.

Stars have to be above a particular weight to go supernova - the sun will grow into a red giant, and then, once it burns most of it's hydrogen, collapse into a brown dwarf.

You'll need to pump a huge amount of energy to do this.

Thanks for sharing this. Nice learning more about our Universe on Christmas day :)

Got me curious, how large the impact of a dying sun or a changing planet ..

According to Hindu cosmology, there is no absolute start to time, as it is considered infinite and cyclic. There are multiple universes, each takes birth from chaos, grows, decays and dies into chaos, to be reborn again. Further, there are different and parallel realities.

According to the Lord of The Rings, the world was sung into existence by Eru Ilúvatar and his Valaar. Elves, orcs, trolls, goblins and other creatures also came into existence.

my money is on Lotr, not Hindu

As much fun as it is to hate on religious beliefs, the Hindu version actually sounds close to scientific theories, no?

No, not really. Entropy only goes in one direction. The universe began in a state of complexity and diversity, and it's history since then has been the story of flattening, cooling, mixing, evening out into boring eternal sameness.

That only counts for closed systems. Does that pertain to our universe? We don't know; We can not see a limit, to say the least, and we have absolutely no agreeable model for any kind of edge. The idea that U closes in on itself, like the surface of a baloon, without any borders, is indeed reminiscent of hindu's Darma idea. It is rather descriptive of our mode of thought: cyclic and self centered; focused on origin and phobic of ...

end of story

The universe is by definition a closed system. The universe is all that exists, if there is something that could have an effect on it, it would be part of the universe.

The universe is expanding, distances are getting bigger, and there is no reason to think that it'll suddenly decide to stop and get small again.

Balloon theory was blown up by the discovery of an increasing cosmological constant (aka dark energy).

Once a fire has burned to ash, you can't turn it back into wood again. Cyclical time is wishful thinking, contradicted by all evidence.

You are making the mistaking of supposing you conclusion as hypothesis, don't you. Because:

> The universe is by definition a closed system.

There is no de-finit-ion, that's my hole point (excuse the pun, it fits better than any other time)

> The universe is all that exists, if there is something that could have an effect on it, it would be part of the universe.

Yes sure, but what if it's endless? That's not closed in the sense of thermodynamics I don't think.

To conclude from your statement, that the universe is a closed system, kind of requires to presume universal entropy increase, in case of infinity. I can't do the maths though, so I might be wrong. It's just a hunch.

> The universe is expanding, distances are getting bigger,

The visible ...

background radiation may invite inference, but really you get interference.

> and there is no reason to think that it'll suddenly decide to stop and get small again.

In a e.g. 10^50 years would not exactly be suddenly

> Once a fire has burned to ash, you can't turn it back into wood again. Cyclical time is wishful thinking, contradicted by all evidence.

I don't disagree.

Does that mean ancient Hindus had some actual, credible insight into quantum mechanics, relativity and parallel universes? No... the myth of a cyclical universe is a metaphor drawn from the observations of cycles of death and rebirth found in nature, particularly in the seasons, and plenty of religions draw from it.

It's easy to take these mythological concepts and restate them in a way that seems to imply hidden scientific knowledge or awareness - Christians have done that with the Bible often enough:I know some who quite literally believe the locusts mentioned in the book of Revelations are Apache helicopters, for instance.

But any resemblance between the flights of fantasy in religion and scientific truth are at best coincidental when the science was arrived at through experimentation which depended on generations of knowledge about the physical world the ancients didn't have. Simply sounding kind of correct in hindsight doesn't count for anything.

Please do not take HN threads further into religious flamewar.

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