Can life emerge around a white dwarf?
centauri-dreams.org
centauri-dreams.org
White dwarfs are also indefinitely stable; they keep cooling over billions of years to become black dwarfs. Then, over >10^100 years, all elements heavier than iron will decay to 56Fe by various processes such as fission and alpha emission. All atoms lighter than iron combine by nuclear fusion reactions, building gradually up to 56Fe. All of this can happen via quantum processes at zero temperature. So they end as lumps of indefinitely stable cold iron.
Intelligent life can hang around white dwarfs for a long time. Good candidate star type for Dyson spheres.
Could tidally locked planets be suitable for life?
https://en.m.wikipedia.org/wiki/Mercury_(planet)#Spin-orbit_...
Probably. Well, usually. If something gave that planet a very hard knock, it could spin up for a while, especially if it's around the outer limits of the proposed habitable zone.
> Could tidally locked planets be suitable for life?
Definitely. Depends how well they're able to redistribute heat from the hot side to the dark side. So atmospheric composition and water content (also the presence and extent of surface water) would be the decisive factors. You'd get wild weather, though.
I'm less optimistic. Between the fraction of the planet's surface that's suitable for life, the lack of tides, the (likely) lack of plate tectonics, and impairment of the various cycles ( https://en.wikipedia.org/wiki/Biogeochemical_cycle ) - tidal locking to the star will profoundly degrade the planet's suitability for life.
Tidal locking may also rule out having a planetary magnetic field. Though "protect the atmosphere" may not matter much, if said atmosphere (plus the water) has all condensed and frozen on the dark side of the planet.
The thing about a tidally locked planet, and about marginally habitable planets in general, is that whatever the average, there are a wide range of surface conditions and often the spectrum is large enough that some subset of them are habitable.
But for real what is it called when the things you're saying don't necessarily rhyme with the original phrase but have a similar cadence?
Which means there is a constant "spectrum" of climates in between, and you only need one of these thousands of microclimates to be beneficial for creating life.
So this may be the planets most suitable for life, if this theory I just made up has any validity!
The conclusion was that perhaps there could be a ring around the planet, at the border of the side facing the sun from the side facing away from the sun. That ring could be a habitable zone.
Not that I think tidal locking is a blocker for life but it’s also not a big deal since large moons are extremely common and therefore the tidal locking is not guaranteed.
Assuming no proton decay, of course.
To get over this mental hurdle we say ‘it’s not slowing down it’s reaching your minimum speed faster!’
I know nothing about racing, is it maybe about reaching a higher minimum speed by doing so before the curve?
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Obviously, you want to brake as late as possible while still reaching the minimum speed demanded by the radius of the turn and your tires/downforce, which keeps your average speed as high as possible before the turn. But it very easy to get in a habit of braking too late, overshooting the turn, and taking a sub-optimal trajectory, which would be passed by someone who braked sooner and used some additional physics concepts.
The absolute fastest way is to brake as late as possible without overshooting, start the turn while you are about to let off the brakes (when the weight of the car has shifted towards the front wheels while braking, so you get more grip on your tires which are doing the steering), and as you let off the brakes, the car has rotational inertia that carries through the turn without needing the tires as much. (but too much rotational inertia = spinout.) Once you have the rotational inertia, you can start giving it gas before you finish the turn, and if the car is RWD, use the engine/oversteer to both increase your speed again and give you extra force pushing you through the inside of the turn. (By getting slightly too much inertia at the start of the turn (but not enough to spin out), then at the end of the turn, when your car would go off the outside of the track, instead have it slightly over-rotate the turn, so that you can use the engine to angle your forces both forward and into the turn, to help you finish without going off.) This way you get to use the engine to make some of the turn instead of the brakes for all of it, which is obviously faster. Then straighten the wheel when you've exited.
Drifting is just over-playing into the above mechanics, getting too much inertia too soon and doing a sideways burnout while countersteering (to bleed off the excess rotation) through the turn to look cool. The fastest is halfway between drifting and "driving naive", aka braking early and coasting through like normal road driving.
I play racing sims and couldn't win consistently until I understood all the above.
The galaxy isn’t empty, however. The proton would be orbiting, emitting such waves, and yes, would slow down.
We will probably just keep downgrading its probability into more and more absurdly low values.
Now imagine multiple ones with life. Someone out there in the vastness of the cosmos might be LARPing Buck Rogers or Commando Cody.
Simple rockets could take you everywhere. It’d be like The Expanse but without the physicists nightmare fusion torches. Such things can maybe be built but it’s many orders of magnitude harder. These folks could be living the dream with 1950s level tech.
They probably look like crabs though.
Such a civilization would also have endless free energy via solar harnessed from the sun side and continuous prevailing powerful winds. The latter would probably get tapped first. Huge wind turbines would just always spin.
This would be true from their dawning of industry, which would be interesting. No energy wars. I’m sure they’d find something else to fight about if they were aggressive and territorial like us.
Unless life can survive & thrive in the remainder. Which I’m sure it can and does.
The most habitable region would probably be the twilight zone but “life will find a way” as Jeff Goldblum famously said. Life would have been evolving for billions of years in that environment before intelligence arose.
The temperature gradient might not be as nuts as you’d think. A thick atmosphere would develop powerful prevailing currents that would move heat from the hot side to the cold one, basically a heat engine. It would keep the hot side from being insane and the cold side from being cryogenic. My guess is that the far poles would be extreme but anywhere from 1/3 to 2/3 of the non-twilight sides would be potentially habitable by something.
If there were large oceans you'd get prevailing currents there that would move heat too.
There’d also be a water cycle. Imagine regions of the hot side where it rains a lot. You might have this hot steamy jungle in eternal daylight, meaning 2X the energy available for photosynthesis.
There’d probably be critters that would migrate around. I can imagine stuff living on the night side by eating those, scavenging, etc.
I wonder if an environment with massive prevailing winds would drive the evolution of wind energy harvesting? Imagine a big tree like thing with big leaves or vanes shaped to flap in the wind and specialized cells that use that mechanical energy to make food and nutrients. Muscles go from sugars to motion. Seems plausible that something could go the other way, especially with billions of years of evolution and a massive amount of energy available that way.
If that kind of thing evolved you could have wind powered ecosystems on the night side and solar powered ones on the day side.
Lots of possibilities.
Travel times between inner planets would be very short, I admit.
If there are lots of planets in closely spaced orbits I'd think orbital resonances could force planets into elliptical orbits, which would drive strong tidal heating, as on Io (but more so, due to the much stronger gravity of the primary.)
It's crabs all the way down. https://en.wikipedia.org/wiki/Carcinisation
Or would tidal locking somehow prevent it?
I would imagine that if intelligent life can build a Dyson sphere, it can probably travel to different stars as well.
The only exception that we know of is our own Solar System. Where Jupiter acts like a vacuum cleaner to reduce material that might hit Earth. We knkw of no other system with both Earth-like planets and gas giants. Given how catastrophic the remaining asteroids have been for us (bye bye dinosaurs), this is unlikely to be a coincidence.
Unless we find a similar arrangement around a white dwarf, the time spent in the habitable zone isn't the only important factor for stability over evolutionary time frames.
Isn't this a current limitation of our exoplanetary detection capabilities rather than something we know about other star systems in general? IIRC exoplanets are most easily discovered by the effect they have on their parent star's brightness when transiting it and/or due to causing the parent star to "wobble". Both those methods would tend to favor finding close and massive planets without necessarily ruling out smaller/more distant ones.
Have exoplanet detection methods improved since I last read about them?
They also favor ones whose orbit passes between us and their star, which dims the star and lets us see it. If the planet’s orbit doesn’t block the star, we’ll never know it was there using our current toolset.
I read somewhere that only like 2% of all planet’s have orbits that come between us and their star—which seems like a plausible figure to me, it’s a number you can probably derive from some simple math. This means until we find other ways to observe planets, we are only able to see a very small number of them out there.
Incidentally if other intelligent life is out there planet hunting using the same method of observing planets pass between the star and the observer, it means the odds of them finding earth are pretty small. They’d have to be positioned such that the earth comes between our sun and their line of sight.
Highly recommend to a certain type of person. Many of whom frequent this message board !
The hydrogen bonds allow lots of interesting processes, and it gets used in many many foundational biological functions as hydroxyl groups.
The chemistry of such a simple molecule is difficult if not impossible to replace, and if you have it, the processes that we are familiar with are already efficient enough that there wouldn't be an advantage to not using them.
Is it possibly there are configurations of life, such as not using either DNA or RNA? Sure. Is it likely that we wouldn't recognize that it is life? I doubt it very much. Aside from virii which likely devolved from living things rather than forming along side them, it's not hard to make a distinction at all.
Perhaps mostly in terms of genesis, but also sustainability and even given theoretical evolutionary differences for hypothetical aliens.
But genesis is really the only discussion that matters. Which is also very true for those that believe that there is a good possibility for alien Life.
The math is beyond me to do, but I once got into a conversation with Claude that sought to find the probable distance of the nearest exoplanet that has possible Earth like conditions matching only a couple of additional factors that aren't commonly considered. Whereas I have dozens more. Claude's estimation was that the nearest such planet would be over two million light years away.
Another conversation sought to understand the probability of an exact replica of this solar system somewhere else in the Universe. That probability is zero.
Yet the origins of life are elusive, and perhaps even multiple and relative, that the origins of life might just be a process the universe does countless times, independently. Or perhaps the seeds all started long ago, and life on this side of the universe is related to life on every side of it.
There's nothing to do but speculate until proven otherwise, since we don't actually know what those steps exactly are. My personal suspicion is that we are more likely to find life in earth like conditions than anywhere else, though.
Given the right conditions, such as Earth, life isn't hard. It showed up almost immediately.
This also means other planets (like Venus or Mars are to Earth) would be visible in the sky as perceptible disks.
(Jupiter itself would be much larger still).
and less fun than speculating about Gods preferenc in tooth care, paste or powder?
Everyone agrees, right!, that we need a several orders of magnitude greater power space based telescope, solely devoted to examining extra solar planets,and then just see what is there. No matter what, it will be very interesting,and generate data usefull in many lines of study. That, or there is an astronomicaly slim chance we will get lucky and someone out there is broadcasting on a frequency that we are look8ng at. Starship changes the equasion, and its time to get the job, done.Now. Think about it, the whole world will drop tools and watch, everytime a new planet comes into focus. Way better than what we are watching now, and will cost, a whole lot less. tick twitch mega goog tube, blarg!
* (and I am admiring the specificity of that HN acct)
note wrt to comment elsewhere in this thread that Forward was also involved with physical aspects of the Integral Trees/Smoke Ring world build.
Stars go through the red giant phase before becoming white dwarves, so they will swallow all the planets close to the star. And blow away any remnants of the accretion disk.
I guess a star with a Jupiter-class planet that survived the red giant phase might qualify. But then the conditions will have to be just right for the captured planet to end up near the star.
Life doesn’t take very long to appear, perhaps just a few million years. We keep revising the number down on earth.
It’s possible, and perhaps even likely, that most white dwarfs host life at some point in their lifecycle, when they’re cool enough.