Super-Earth civilization

[Colin Robinson]

Thanks for the kind effort to help, but I did actually read to the end of the post. It's impossible to tell from context if the ":no:" means "no, everything I just wrote is counterfactual" or "oh no, poor giraffe". I took it to mean the latter, since the former would be ... odd.

Remembering the topic of this thread, perhaps the point was... If something as extremely tall and spindly as a giraffe can walk about in Earth gravity without being driven to extinction by frequent lethal falls, can we rule out something moderately tall and spindly — an alien with generally human-like proportions — walking about on a world with somewhat higher gravity?

[grant hutchison]

Remembering the topic of this thread, perhaps the point was... If something as extremely tall and spindly as a giraffe can walk about in Earth gravity without being driven to extinction by frequent lethal falls, can we rule out something moderately tall and spindly — an alien with generally human-like proportions — walking about on a world with somewhat higher gravity?

Well ... yeah. That's the point I was making:

My point is really that there is no necessity to scale in precise (or even approximate) inverse proportion to gravity. We have very large animals, and very tall animals, that operate quite effectively in Earth's gravitational field. So increased weight and increased hydrostatic pressure differences aren't show-stoppers - gravity demonstrably doesn't force biology to occupy a very narrow scale range.

My later posts merely fleshed that out with a little mathematics. Did you think I was saying something else?

Grant Hutchison

[Colin Robinson]

Well ... yeah. That's the point I was making:My later posts merely fleshed that out with a little mathematics. Did you think I was saying something else?

I didn't know what point you were arguing overall as I hadn't read all your posts in this thread. Thank you for explaining. I agree that increased weight and increased hydrostatic pressure aren't necessarily show-stoppers.

[grant hutchison]

I didn't know what point you were arguing overall as I hadn't read all your posts in this thread. Thank you for explaining. I agree that increased weight and increased hydrostatic pressure aren't necessarily show-stoppers.

So I still don't know what Barabino was trying to say with the toppling (or non-toppling) giraffes.

Grant Hutchison

[Colin Robinson]

So I still don't know what Barabino was trying to say with the toppling (or non-toppling) giraffes.

Grant Hutchison

Maybe that an actual animal, such as a giraffe, can be a stronger argument that the maths and physics principles being discussed by yourself and Roger Moore?

[grant hutchison]

Maybe that an actual animal, such as a giraffe, can be a stronger argument that the maths and physics principles being discussed by yourself and Roger Moore?

Which is why I led with a reference to actual animals:

We have very large animals, and very tall animals, that operate quite effectively in Earth's gravitational field. So increased weight and increased hydrostatic pressure differences aren't show-stoppers - gravity demonstrably doesn't force biology to occupy a very narrow scale range.

I've bolded it to help you.

Grant Hutchison

[Barabino]

Thanks for the kind effort to help, but I did actually read to the end of the post. It's impossible to tell from context if the ":no:" means "no, everything I just wrote is counterfactual" or "oh no, poor giraffe". I took it to mean the latter, since the former would be ... odd. But if it's the former, then it seems Barabino and I are in complete agreement, and I just added a detailed supporting argument. (A shame if so, because I wanted to know more about those falling giraffes - the fact that they do fall so rarely is something of a neurological puzzle.)

Grant Hutchison

in other vbulletin forums, ":no:" makes an animated gif of a shaking head... meaning amazement and skepticism...

[Barabino]

So I still don't know what Barabino was trying to say with the toppling (or non-toppling) giraffes.

that they keep on living, and they usually die because lions devour them, not for falling and hitting their head... (a rare event indeed: usually they manage to fall keeping the head off the ground)

[grant hutchison]

in other vbulletin forums, ":no:" makes an animated gif of a shaking head... meaning amazement and skepticism...

Yeah, I knew which emoji you were hoping for, but it was still impossible to work out from context what that emoji was intended to transmit in this case. People use the "head shake" (and the related "head shake, raised hand") for so many things - I've seen it used to transmit everything from a patronizing "you really have no idea, do you?" to "I disagree" via "I don't approve". Because you'd written all that stuff about giraffes falling and hitting their heads as a statement, rather than a question, I assumed the :no: was signalling "I don't approve" (of giraffes dying) rather than "I now declare that I disagree with my own statement". Seems I was wrong - thanks for clarifying.

Grant Hutchison

[Roger E. Moore]

Some references for those interested in the discussion of life on super-Earths. Reddit first, a couple of threads.

Life on extremely high gravity planets
https://www.reddit.com/r/Speculative...avity_planets/
Makes an interesting point about how seeds would be spread across the land on a planet with very dense atmosphere. I would suggest ant-like creatures could carry fallen seeds off to their inland colonies, losing some or perhaps planting some to create more food.

Issues for life on a super-earth?
https://www.reddit.com/r/IsaacArthur..._a_superearth/

===

The most interesting material was an article in the January 2015 issue of Scientific American, which apparently looked at the topic in detail. I say "apparently" because the online article is behind a paywall.

https://www.scientificamerican.com/a...in-our-galaxy/
Planets More Habitable Than Earth May Be Common in Our Galaxy
By René Heller, Scientific American January 2015

However, the text is summarized in Wikipedia, the relevant section being presented below with the usual caveats about quoting from Wikipedia.

https://en.wikipedia.org/wiki/Super-Earth#Habitability
"According to one hypothesis, super-Earths of about two Earth masses may be conducive to life. The higher surface gravity would lead to a thicker atmosphere, increased surface erosion and hence a flatter topography. The end result could be an "archipelago planet" of shallow oceans dotted with island chains ideally suited for biodiversity. A more massive planet of two Earth masses would also retain more heat within its interior from its initial formation much longer, sustaining plate tectonics (which is vital for regulating the carbon cycle and hence the climate) for longer. The thicker atmosphere and stronger magnetic field would also shield life on the surface against harmful cosmic rays."

If anyone has that issue of SA from 1/2015, perhaps they could summarize from it.

[Roger E. Moore]

There is always the question of atmospheric pressure on a super-Earth. The LHS 1140b example is good as mass and radius are both known to a fair degree, as it is a transiting planet. I will poke around and see what there is to find. Would the height of the atmosphere be shorter than on Earth, because of the higher gravity? On a mini-Neptune I can see the atmosphere would be high as it would include hydrogen and helium, in all likelihood.

[grant hutchison]

There is always the question of atmospheric pressure on a super-Earth. The LHS 1140b example is good as mass and radius are both known to a fair degree, as it is a transiting planet. I will poke around and see what there is to find. Would the height of the atmosphere be shorter than on Earth, because of the higher gravity? On a mini-Neptune I can see the atmosphere would be high as it would include hydrogen and helium, in all likelihood.

Scale height (the vertical distance over which atmospheric pressure decreases by a factor of e) is directly proportional to temperature, and inversely proportional to surface gravity and the mean molecular mass of the atmosphere.

Grant Hutchison

[eburacum45]

When describing humans in the far future who have become adapted to higher gravity environments, I do like to make them shorter, since they would weigh less and have less far to fall. I also like to give them knee-pads and elbow pads, preferably as part of their physiology, so they won't get hurt so easily falling down when naked.

But if giraffes have an innate tendency to not fall over, somehow, that would be a very useful trait or skill to give to these hypothetical high-grav humans.

[Roger E. Moore]

Had a funny idea. M.C. Escher's "Curl-Up" creature might be adaptable here to roll down shallow inclines, gaining speed that legged motion might not achieve. It would be a good flight tactic for prey as they could escape from walking/running predators. If a high-gravity planet tends to pull down mountains into hills, as one source noted earlier, there you are.

https://en.wikipedia.org/wiki/Curl-up

It might be a dumb idea but, hey, you never know.

[Roger E. Moore]

According to this paper, LHS 1140 is a large "Population I" super-Earth. The paper proposes four types of super-Earths that could be agreeable for life, having liquid water on the surface.


https://arxiv.org/ftp/arxiv/papers/1903/1903.05258.pdf
The Super-Earth Opportunity - Search for Habitable Exoplanets in the 2020s
Renyu Hu, et al. (Submitted on 12 Mar 2019)
The recent discovery of a staggering diversity of planets beyond the Solar System has brought with it a greatly expanded search space for habitable worlds. The Kepler exoplanet survey has revealed that most planets in our interstellar neighborhood are larger than Earth and smaller than Neptune. Collectively termed super-Earths and mini-Neptunes, some of these planets may have the conditions to support liquid water oceans, and thus Earth-like biology, despite differing in many ways from our own planet. In addition to their quantitative abundance, super-Earths are relatively large and are thus more easily detected than true Earth twins. As a result, super-Earths represent a uniquely powerful opportunity to discover and explore a panoply of fascinating and potentially habitable planets in 2020 - 2030 and beyond.

[grant hutchison]

But if giraffes have an innate tendency to not fall over, somehow, that would be a very useful trait or skill to give to these hypothetical high-grav humans.

I'm not sure there's much you could do to a human to emulate a giraffe, and still have a human.
The trick to not falling over is to be able to keep your centre of gravity above your base of support. Giraffes can maintain a broad base of support when galloping because they have four long legs that are capable of considerable sideways movement at the hip. They have time to make adjustments because, although they move fast, the period of pendulum oscillation of their legs is long, and an off-balance situation takes time to develop. And they have good control of their centre of gravity because they have a big heavy head on the top of a long powerful neck, which they can quickly move around through a wide arc to make fine adjustments.

Grant Hutchison

[Roger E. Moore]

Had a funny idea. M.C. Escher's "Curl-Up" creature might be adaptable here to roll down shallow inclines, gaining speed that legged motion might not achieve. It would be a good flight tactic for prey as they could escape from walking/running predators. If a high-gravity planet tends to pull down mountains into hills, as one source noted earlier, there you are.

https://en.wikipedia.org/wiki/Curl-up

It might be a dumb idea but, hey, you never know.

Three more "Curl-Up" links, one to a video, one to the original drawing, and one to a 3D put-together model.

https://www.mcescher.com/gallery/bac...lland/curl-up/

https://www.instructables.com/id/Art...Curl-up-Model/

https://www.youtube.com/watch?v=896XoGW6erQ

[Roger E. Moore]

Intriguing artwork (speculative biology) of life on a high-gravity world. Interesting point that with a thick atmosphere and a greenhouse effect that avoids being runaway, the skies might be largely overcast, assumedly from water vapor.

https://www.sciencephoto.com/media/3...-world-artwork

Same idea, from Ron Miller, but not overcast. Looks like a scaled pangolin critter in the foreground.

https://spaceart.photoshelter.com/im...000R4bHWGSv.AY

[eburacum45]

For what it's worth, here's a fictional superterrestrial life-bearing world I made for Orion's Arm;
the pentapod and the dinopillar are the only two animals I've put together so far.
https://www.orionsarm.com/eg-article/4eea8e230eb7c

[Tom Mazanec]

I thought giraffes had straight necks and could not significantly curve them?

[grant hutchison]

I thought giraffes had straight necks and could not significantly curve them?

Two words: "neck fighting".
For an example, take a look at this YouTube video: https://www.youtube.com/watch?v=KQLPL1qRhn8

Grant Hutchison

[Tom Mazanec]

Thanks, Grant.
Giraffes are almost as cool as mongooses.
Almost.

[Barabino]

If a sapient species develops an industrial society on a high gravity planet, could it plausibly colonize space? Reaching space would be extremely difficult by itself, and replicating the physical conditions of their world on a space station could be a nightmare. We have yet to do so despite nearly 6 decades of spaceflight, how much harder for heavyworlders?

speaking as a space enthusiast (a space pasdaran ), I can't imagine how an industrial society, still packed with energy sources (petrol, uranium etc. are still abundant...) could manage to do LESS than we're doing now... tsk, tsk

MarsTransitionV.jpg

[Tom Mazanec]

A fictional depiction of an inhabited superearth:
http://www.worlddreambank.org/L/LYR.HTM

[publiusr]

I like the Sea of Fire
http://www.worlddreambank.org/L/LYRYTHLO.HTM

[Barabino]

A fictional depiction of an inhabited superearth:
http://www.worlddreambank.org/L/LYR.HTM

it reminds me of the Philippines or Java: huge tropical islands filled with lush jungles and friendly girls, all of them is on the pill and willing to please (in EVERY sense) the young and healthy first-world generous tourist...

dumplings-2392893_1280.jpg

[Barabino]

Credit CHRISTIAN DARKIN / SCIENCE PHOTO LIBRARY
Caption High gravity alien world. Artwork of alien life forms on a planet with high surface gravity. A rocky planet that is 1.2 times larger in diameter than the Earth would have twice the Earth's mass and three times its surface gravity. Life forms would evolve to survive the crushing pressures, so will be stockily built, with flattened, low profile bodies. Such a planet is likely to have a dense atmosphere and constant cloud cover,

S9200170-High_gravity_alien_world,_artwork.jpg

I'd expect for those "snakes" to be sticking to the ground, bending sideway, NOT bending up and down (on the earth, no animal does that )

[Barabino]

thinking better about it, cobras sometimes raise their head over ground, but they stay still, do not "flow" forward when head is up...

1.jpg

I must confess I've seen neither a cobra in the wild, nor a vipera

[eburacum45]

it reminds me of the Philippines or Java: huge tropical islands filled with lush jungles and friendly girls, all of them is on the pill and willing to please (in EVERY sense) the young and healthy first-world generous tourist...

dumplings-2392893_1280.jpg

Although (as a worldbuilder myself) I admire Chris Wayan's planets and attention to detail (those planets are all modelled in 3D, using plaster and paint), I find the descriptions of the societies on those worlds somewhat embarrassing. Sure, there might be a few planets that are hedonistic paradises with loose morals, but surely not all of them?

[eburacum45]

One quick and dirty way that a high-gravity world might launch into space is by using nuclear pulse propulsion.
https://en.wikipedia.org/wiki/Projec...ar_propulsion)
Using fissionable materials, a series of small bombs could lift even quite heavy craft into space; on a hi-grav world, 'heavy' applies to quite modest spacecraft.