

Can life exist on a planet without a star? - Hooke
http://aeon.co/magazine/science/can-life-exist-on-a-planet-without-a-star/

======
3pt14159
Could you imagine being that lifeform that cored through the kilometres of ice
to finally find an empty space with starlight shining down on you? Alone in a
void, the closest celestial being is 10 light years away. Fission could power
you for a long time, but rather than looking at the planet as a place fixed,
the species could begin to think about where to _go_. As a _planet_. They may
question whether life on a planet orbiting a sun is even _possible_ (wouldn't
it be too hot to form an ice layer?!) but where else could they head?

Fascinating.

~~~
stevenh
I bet the sky would look very different to them, too. If they did evolve eyes
at all, it would probably only be in order to detect thermal radiation from
other life forms on the planet; so infrared, microwave, and/or radio
frequencies, but not visible light. They may even be able to plainly see the
cosmic microwave background with the naked eye. It might even be blindingly
bright to them.

------
betawolf33
This reminds me of a short story about Earth being flung from the solar system
by a rogue star. People survive, and one family in particular survives by
boiling frozen oxygen 'snow' over a fire.

[https://en.wikipedia.org/wiki/A_Pail_of_Air](https://en.wikipedia.org/wiki/A_Pail_of_Air)

[http://www.baenebooks.com/chapters/0743498747/0743498747___6...](http://www.baenebooks.com/chapters/0743498747/0743498747___6.htm)

~~~
serf
>
> [https://en.wikipedia.org/wiki/A_Pail_of_Air](https://en.wikipedia.org/wiki/A_Pail_of_Air)

Los Alamos, Argonne, and Tana Tuva.

Was Tana Tuva a topic of discussion during this time period? I remember
Richard Feynman wrote quite a bit about it, too.

~~~
andyjohnson0
Feynman's friend Ralph Leighton wrote about Felnman's long-standing desire to
go there [1]. The BBC Horizon programme had an episode called "The Quest for
Tannu Tuva" [2] which might be on youtube.

[1] [http://www.amazon.co.uk/Tuva-Bust-Richard-Feynmans-
Journey/d...](http://www.amazon.co.uk/Tuva-Bust-Richard-Feynmans-
Journey/dp/0393320693)

[2] [http://sciencek.com/video/1151/horizon-1988x25-the-quest-
for...](http://sciencek.com/video/1151/horizon-1988x25-the-quest-for-tannu-
tuva-1988-07-04/)

------
jaytaylor
"Most of Earth’s internal heat was delivered by the giant collisions that
built the planet, a large portion of which remains locked inside its crust.
This heat slowly trickles to the surface, providing a source of internal
energy that has endured since the Earth formed. This interior heat will last
for billions of years to come, but it’s a puny amount of energy, 3,000 times
smaller than the sunlight that blasts the Earth daily."

Do this mean 3,000 times less than the Suns total daily output, or 3,000 times
less than the sunlight that physically hits the earth daily?

I suspect the latter, but I still find this surprising. If daily sunshine
hitting the earth is so massive then let's make solar work! If we could just
collect even a fraction..

~~~
yongjik
I don't think this sentence is true:

> Most of Earth’s internal heat was delivered by the giant collisions that
> built the planet, a large portion of which remains locked inside its crust.

In 19th century, Lord Kelvin estimated the age of Earth using this method,
arriving at somewhere between 20 and 400 million years[1], much shorter than
4.6 billion years currently accepted. It turns out radioactive decay keeps the
Earth's inside warm for a much longer time. (I.e., assuming Kelvin's
calculation was correct, without radioactivity the Earth's core would have
frozen over within the first 400M years.)

[1]
[http://en.wikipedia.org/wiki/Age_of_the_Earth#Early_calculat...](http://en.wikipedia.org/wiki/Age_of_the_Earth#Early_calculations)

~~~
hyperpallium
Tidal friction from the moon (and to a lesser extent from the sun) would also
have contributed.

------
bjwbell
Started off good and then lost me when he talked about using them for stepping
stones to the stars. I'm confused about that.

A rogue planet in itself makes a terrible colony. And by stopping at one you
about double(!) the energy/time needed to leave the solar system.

~~~
jerf
At the moment, the most feasible way I see to the stars is via laser-launched
ship. The cruel mistress that is the rocket equations don't favor even a self-
contained starship driven by 100% efficient antimatter reactions, to say
nothing of things that might actually work. Leaving your engine behind is
almost a necessity. But even if you try to launch things from a solar-system
based laser station the physics still don't really work out well. Light-years
is a long way to maintain a focus for the beam.

Some have decided this means star travel is impossible; I say it just limits
how quickly we can do it. We could launch very large ice asteroids with
nanotech unmanned fusion stations that construct lasers ("vigorous handwave
about magic here") and create ourselves a series of stepping stones to a star.
It would take a long time, not least of which is because we would also need to
set up the "stepping stones" to stop us on the other end, too! But in theory
it seems like it would "just" be a matter of time. Lots of time. But a whole
star system on the other end! It's a pretty big payoff for a strapping young
Kardashev II civilization.

(Note that "just send information" only works _after_ you deliver a physical
package to the other end which would be capable of receiving it and doing
something with it, and even nanotech is unlikely to be able to land anywhere
to begin its lengthy self-replicating process to bootup civilization on the
other end if it's merrily passing through a system at 80% the speed of light
relative to the local rest frame.)

If you were lucky enough to stumble on to one of these planets in the way, it
would provide a pretty nice shortcut to setting up your bridge by providing
you a nice, huge power source (if you can find a lot of hydrogen lying around
somewhere, which is a reasonable guess) that's already more-or-less at rest in
the galactic frame, allowing you to use it to relatively easily create more
stages on the enormous pipeline, and allowing you the ability to relatively
easily replenish the stages in the middle. (If that's even desirable...
perhaps the stages can be retargeted to other stars or something once the
bootstrap package is successfully delivered.)

... of course, the article's starting with "10,000 years in the future" is
probably not a terrible guess about all this, as such things go. This is a
guaranteed-slow process, trading time for space. Tell your great-grandchildren
to ask their great-grandchildren how the initial plans to make the initial
plans for all this are going, and say "hi" to the future for you. Saying "we"
will do this might very well be considered to be rather impudent of me, much
like Napoleon trying to claim some sort of perceptible credit for the Hoover
Dam.

~~~
meric
_It is possible for an observer to accelerate uniformly from their own
perspective for an indefinite period of time in special relativity (the motion
traces out a hyperbola in spacetime asymptotic to the lightcone). The person
undergoing the acceleration doesn 't notice anything changing as time goes on.
All of the relativistic slowing down and time dilation effects etc. that you
mention are seen in an inertial reference frame looking at the accelerating
ship._

[http://physics.stackexchange.com/questions/53587/if-a-
space-...](http://physics.stackexchange.com/questions/53587/if-a-space-ship-
accelerated-constantly-would-its-astronauts-constantly-feel-the)

 _From the ship 's frame, the acceleration would continue at the same rate.
However, due to Lorentz contraction, the galaxy around the ship would appear
to become squashed in the direction of travel, and a destination many light
years away would appear to become much closer. Traveling to this destination
at sub-luminal speeds would become practical for the onboard travellers.
Ultimately, from the ship's frame, it would be possible to reach anywhere in
the visible universe, before the ship has time to accelerate to light speed._

[http://en.wikipedia.org/wiki/Space_travel_using_constant_acc...](http://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration)

If you can build an engine that can constantly accelerate, without having to
constantly throw fuel behind you, e.g.
[http://higherperspective.com/2015/03/nasa-
engine.html](http://higherperspective.com/2015/03/nasa-engine.html), an
astronaut can potentially travel 4 light years in less than 4 years, from
their point of view, because although from Earth's reference point of view
they will always be less than c, as their speed approaches c from Earth's
point of view, there will be time dilation between them and Earth. If from
Earth's point of view they take 4 years and a bit to travel 4 light years,
assuming acceleration to _very_ close to c very quickly, you as an astronaut
will experience the same time as a lot shorter, possibly as months.

From the astronauts point of view, they can travel one light year in less than
one year, if they can accelerate constantly fast enough without dying.

Of course I haven't taken into account the amount of energy that needs to be
involved, except to say, if you're talking about a one-way trip, the time
factor can be overcome, through technology that isn't that impossible.

If you know what's on the other side and it's possible can build a self-
sustainable colony, colonising other planets is perfectly feasible from a
psychological point of view given we have the technology we can accelerate
close to c and decelerate from c, by achieving the time dilation effect.

~~~
jerf
"If you can build an engine that can constantly accelerate... Of course I
haven't taken into account the amount of energy that needs to be involved..."

Yes, once you throw away all the hard problems, space travel is easy.

Once you take them back into account, and seriously consider the problem as an
_engineering_ problem and not a _science fiction_ problem, which, alas, many
people have been sort of accidentally been trained to do because of the
prevalence of science fiction, it starts looking _really, really_ hard again,
like, "The most plausible answer to the Fermi paradox is that star travel is
impossible"-level hard.

(Which, again, isn't my opinion... I think it just means it takes a "bit"
longer (you know, two or three orders of magnitude, just a trifling detail)
but assuming that all possible societies in all the universe are as impatient
as modern-day humans is a very strong assumption. But it isn't such a crazy
argument that it can simply be dismissed... real space travel is _hard_.)

~~~
meric
If you look at the reactionless drive I linked to, and if it works and can be
scaled up, and in the future we can have mini nuclear or fusion power plants,
all of which I see is possible, then the only problem remaining is collision
on the way to the star and whether astronauts can peacefully stay on a small
spacecraft for several years, knowing they are travelling in a one way time
machine and people on earth will die quickly as they travel above c
(technically their destination becomes closer, rather than them actually
travelling this fast) from their frame of reference. I think it is not
unreasonable to expect all of these problems resolved within 500 years, making
space travel between stars a possibility for humanity.

------
JacobAldridge
What sort of speed might some of these rogue planets be moving at? While the
faster they move, the harder it would be to 'latch on' to a stable orbit /
land, could they more than a waypoint to distant stars - might they be a
'spaceship'?

Although this would require us to 1) discover a dark planet, 2) moving at an
appreciable percent of lightspeed, 3) with enough time to reach it, and 4)
heading in the right direction so we could alight at a nearby solar system. If
colonization sounds hard, how about those hitchhiking odds - infinitely
improbable!

~~~
jessriedel
No, there shouldn't be any rouge planets moving fast enough. Stars at our
distance from the galactic center move at roughly 230 km/s, with relative
speeds of 10-30 km/s. The escape velocity from the galaxy is ~550 km/s, which
is something like 0.2% light speed. Very few objects get accelerated above
this speed, and when they do they leave the galaxy (so the probability that we
pass one going by is negligible).

~~~
sdrothrock
> No, there shouldn't be any rouge planets moving fast enough.

For comparison's sake, the only rouge planet that we know of is Mars, which
moves around 24 km/s. :)

~~~
mirimir

        The discovery of hypervelocity stars (HVS) leaving our galaxy with speeds of
        nearly $10^{3}$ km s$^{-1}$ has provided strong evidence towards the existence
        of a massive compact object at the galaxy's center. HVS ejected via the
        disruption of stellar binaries can occasionally yield a star with $v_{\infty}
        \lesssim 10^4$ km s$^{-1}$, here we show that this mechanism can be extended to
        massive black hole (MBH) mergers, where the secondary star is replaced by a MBH
        with mass $M_2 \gtrsim 10^5 M_{\odot}$. We find that stars that are originally
        bound to the secondary MBH are frequently ejected with $v_{\infty} > 10^4$ km
        s$^{-1}$, and occasionally with velocities $\sim 10^5$ km s$^{-1}$ (one third the
        speed of light), for this reason we refer to stars ejected from these systems
        as "semi-relativistic" hypervelocity stars (SHS).
    

[http://arxiv.org/abs/1411.5022](http://arxiv.org/abs/1411.5022)

There could also be hypervelocity planets, right?

Catching up to them would be hard, though.

~~~
jessriedel
> There could also be hypervelocity planets, right?

There could definitely be hypervelocity planets just like planets. However,
the density of these drops dramatically as you increase the speed you're
looking for above the "typical" speed at our galactic radius (~230 km/s),
simply because they are created by chance events. I believe the density of
rouge planets is supposed to be of order the average density of normal planets
in the galaxy (i.e., there might be 3 times as many rouge planets, but not 100
times as many). So finding a relativistic rouge planet nearby enough to be
useful has negligible probability. (They are created by close encounters with
black holes, after all.)

> Catching up to them would be hard, though.

Well, if you're thinking about using them as "space ships", you need to get up
to speed anyways (since the alternative is to just travel on your own).

~~~
mirimir
Yes, that's a good point about density.

If you could catch one, your itinerant colony would have resources at speed
for interstellar travel. You'd only need to accelerate a relatively small
ship. And those resources would include mass for decelerating your ship at
destination. But you couldn't stop for very long, without losing your ride.

------
RIMR
I also wonder about rogue planets near the galactic center. They wouldn't need
to have their own star to get bathed in plenty of light from other nearby
stars.

There would be no such thing as night and day either.

~~~
Retra
You might be underestimating the distance between stars in the galactic
center...

~~~
Crito
It isn't a great source, but this seems to suggest it would actually be pretty
significant:

> _" Near the galactic center, the average distance between neighboring stars
> would be only 1000 AU (about a light-week). If the Sun were located within a
> parsec of the galactic center, there would be a million stars in our sky
> with apparent brightness greater than Sirius. The total starlight in the
> night sky would be about 200 times greater than the light of the full moon;
> you could easily read the newspaper at midnight, relying on starlight
> alone."_

[http://www.astronomy.ohio-
state.edu/~ryden/ast162_7/notes31....](http://www.astronomy.ohio-
state.edu/~ryden/ast162_7/notes31.html)

------
daltonlp
Dark Eden is a recent novel with exactly this premise. It's an excellent book:

[https://www.goodreads.com/book/show/18166988-dark-
eden](https://www.goodreads.com/book/show/18166988-dark-eden)

~~~
rspeer
For what it's worth, I enjoyed the world-building but found the actual plot
too simplistic.

Kind of like _Flatland_ in that regard, I suppose, so it's not terrible.

------
ghostberry
"To have any chance of life – at least life like our own – a free-floating
Earth would need liquid water. And to have liquid water, a planet needs to
keep warm."

Maybe, maybe not.

[http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemis...](http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry#Non-
water_solvents)

------
amelius
On a much larger scale (in both space and probably time), the planet could be
part of a life form (like an electron can be part of us).

------
irixusr
The ontological argument mated with the spaghetti monster and we got this
argument.

I can envision how this planet could exist, and I can't prove it doesn't
exist. Therefore it does. To make it sound scientific I'll replace "it does"
with "it might"

~~~
mcdougle
It doesn't come across like it's trying to really prove anything exists or is
true. Just some fun speculation and what it might mean if it _were_ true.

------
bediger4000
There's another scenario for life-supporting lonely planets. Caltech
Astrophysicist David J. Stevenson has proposed a form of gas giant that can
have a liquid water ocean:

[http://www.nature.com/nature/journal/v400/n6739/full/400032a...](http://www.nature.com/nature/journal/v400/n6739/full/400032a0.html)

Looks like some follow-on work/speculation has happened, too:

[http://www.researchgate.net/publication/237427218_Possibilit...](http://www.researchgate.net/publication/237427218_Possibility_of_Life-
Sustaining_Planets_in_Interstellar_Space)

------
timharding
I just finished reading Dark Star — an entertaining scifi noir epic poem set
on a planet with a dead sun. It isn't going to tell you about the
practicalities of this type of thing but it is a good yarn.

[http://www.amazon.co.uk/Dark-Star-Oliver-
Langmead/dp/1907389...](http://www.amazon.co.uk/Dark-Star-Oliver-
Langmead/dp/190738930X/ref=sr_1_3?ie=UTF8&qid=1428648259&sr=8-3&keywords=dark+star)

------
struppi
"Atomic Rockets" has a section about "Dark Matter Planets" on their "Weird
Astronomy" page. Those planets could even be heated to temperatures where
liquid water can exist by exotic particles - If they are close enough to the
galactic center...

[http://www.projectrho.com/public_html/rocket/weirdastronomy....](http://www.projectrho.com/public_html/rocket/weirdastronomy.php)

------
superrad
Would such planets have a slower rate of evolution without the radiation of
the sun providing mutation, or would it just be mostly contained to the
development of skin?

~~~
pavel_lishin
I would imagine that a 10km ice layer would block most interstellar radiation.

------
V-2
It takes billions of years for life to evolve. How long before a planet
floating freely across the universe gets pulled into some unstable orbit or
falls onto some other (bigger) celestial body

------
humanarity
Attempt at one liner: I was hoping to see a byline of "A new manned mission
plan by the ESA."

------
yCloser
what do you mean "Free-floating planets", everything orbits something that is
orbiting something

