Speaking of renewables in the U.S. why is hydro never mentioned when discussing renewables?!?
Because it makes up a rather limited percentage of generation capacity in the US - and that percentage isn't going to go up significantly. (Weaseling because I'm still on my first cup of coffee and there may be some I'm unaware of.) We aren't building power generation dams in any significant quantity, and that's extraordinarily unlikely to change.
But my analogy is this. Say that you're a pearl diver. You're browsing along a dive forum one day and see a picture from someone on their vacation to a remote tropical island holding a large, rare pearl that they found on a dive. You ask them where they found it, and they tell you they only did one dive and found it in waters of about 15 meter depth off the shore. Wanting to find many of these such pearls, you head out to the island. Now, you have two approaches you could take.
1. Spend a long time carefully doing a geological survey of the water depth around all of the shores of the island. Then do your dives in order of which are most precisely 15 meters deep, regardless of how convenient they are to access. Only move on to areas that are any more or any less than exactly 15 meters deep when you've exhausted all of the known 15-meter depth areas.
2. Go out and start diving wherever the water looks to be at least in the right ballpark of 15 meters depth. Start with the most convenient areas first. Don't obsess over the exact depth - exploring some 10 meter areas, some 20 meter areas, etc, just trying to keep it roughly in the ballpark of 15 meters. Because hey, for all you know, more than 15 meters or less than 15 meters might be an even better diving depth; you've only got one datapoint so far.
Which makes more sense? #2, obviously. Which is the same strategy we should be using with exoplanets in the search for life. We should be "favoring" Earthlike planets, but not obsessing over earthlike-ness in the search. We should be checking out a diverse range that is only "centered" on Earthlike bodies. And we should be focusing on those which lend themselves to easier, more detailed observation first, such as those closer to us and with a more favorable orbital alignment.
** I should clarify that when I say "mollusks", I mean like cephlapods, not like snails
I have no clue where you're coming from. You rightly point out that life takes energy, but then proceed to consider internal sources of energy as worthless, when in reality in the universe far more things are exposed to internal energy than external. And radioactive decay-driven energy sources are only one. For example, Encelaldus's heat seems to be driven by the serpentization of rock, which also releases hydrogen, a potential food source to microorganisms. There are numerous chemical means which can release vast amounts of energy - yes, nuclear energy is many orders of magnitude more dense, but non-radioactive elements are also orders of magnitude more common.
Anywhere that there is heat and fluids (or solids that can undergo solid-state convection) can experience that heat being turned into harvestable forms of chemical energy, because chemical equilibriums are different at different temperatures. For example, at STP conditions, N2 + O2 is favorable, while at high temperatures NO2 is more favorable. N2 + O2 that goes to higher temperatures and forms NO2, which then comes back down to the lower atmosphere, is bringing a source of chemical energy with it.
Since heat differentials can and will be readily converted to chemical energy wherever it's associated with convection of any variety, then any source of heat is a fuel for life - and heat most definitely doesn't only come from nuclear decay - or chemical reactions. It comes also from the rebalancing of layers to a lower gravitational equipotential. It comes from impacts. It comes from tidal heating. It comes from thermal cycling in elongated orbits. It comes from mass loss due to solar wind exposure. There's a vast range of potential heating sources in the universe that can create heat differentials. And heat differentials make exploitable chemical reactions.
You make blind assertions that "these environments wouldn't be likely because of their composition". What do you know about this? You have a sample size of one of chemical processes that have created life. We can't even see deep into our own world to see what other alternatives might exist at higher pressures, let alone in other worlds. Heck, underground doesn't even mean particularly high pressures. Dwarf planets can have Earth-surface pressures at hundreds of meters or even kilometers depth. And life on Earth exists fine in the deep sea, wherever there's energy to support it, where pressures are at over 1000 atmospheres
Deep environments might prove even more prone to organic chemistry. In general, pressure is usually associated with faster reaction rates. You also often have more complex arrangements of possible chemical phases for each compound at higher pressures than with lower pressures. Water for example over its possible temperature range at a particular depth might have 3-5 potential ice phases, a liquid phase, a supercritical fluid phase, and a gas phase. This leads to a much greater range of possibilities for reactions to potentially exploit, because each chemical in each of its phases has the potential it interact with each other chemical in each of its other phases, or in the case of non-metastable forms, at least many of its other phases.
Common theories for the origin of life on Earth usually assume that it wasn't the sun that powered the first forms of life, even though that's the most convenient source of energy on our planet. Photosynthesis is much more complicated than most forms of chemosynthesis. Environments like black smokers, volcanic pools or acidic waters within deep iron-rich minerals seem like far more likely candidates.
Intelligence evolving within creatures that live in liquids? Oh, we've never seen that before!
The only reason that our deep seas seem less rich with competing life is that our deep seas are usually relatively energy devoid. Which says absolutely nothing about subsurface layers on other planets. Wherever our deep seas are not energy devoid, such as around black smokers, they tend to be flush with life.
I think it's silly in the regards that we have precisely one datapoint about the sort of environments in which life may exist, which is pretty terrible in terms of making any sort of definitive statement. I'd much rather they keep their options open, check out a wide range of environments, and just look for signs of "things that are hard to explain", whatever they may be. "Hmm, this body has both a strong oxidizer and a strong reducing agent in its atmosphere - how is that happening?"
I'm not saying "check planets in random order" or anything of that nature. Just that I don't think it's critical to obsess over being sure to examine them in order of "earthishness" from highest to lowest. We need to be looking at a diversity of worlds.
Heck, we don't even know whether the surface of a body is the best place to look, most life in the universe might be in sub-crustal layers for all we know. Certainly would partially help explain the Fermi paradox, if it were such that we rare "surface dwellers" have a far easier route to the cosmos than something that needs to be under gigapascals of pressure to survive and whose radiating transmissions, if any, would be blocked by their planet's crust.
We can tell how habitable it is by how much it causes a start to warble
Chirp chirp chirp, triiiiiiiiiiiillll, triiiiiiiiiiiiiiiilllll! Chirp triiiiiiiiiiiiiiiiiiillll! Coooo-oooo! Cooooo-oooo! Chirp chirp chirp!!!
If you want to keep "doing the math" and if you want to be called "hard sci fi", you need to do the math right. You can't say that because you've got 50 liters of oxygen that you're going to get 100 liters of water because O2 + 2 H2 = 2 H2O. Yet Weir does exactly that, over and over and over again, mixing up moles, liters, and kilograms. One of dozens of categories of huge fundamental science mistakes that he keeps repeating.
I'm sorry, I missed out where "accuracy" and "popularity" became interchangeable terms. I was responding to a post talking about the book's amazing scientific accuracy, when in reality it's a veritable MST3K of glaring science errors on almost every page. Or at least glaring to anyone who knows anything about the scientific fields involved.
At least with "soft" sci-fi where they don't try to explain how everything works you only get hit over the head with science problems whenever they describe a situation that's literally impossible. With bad pseudo-hard-sci-fi you get hit over the head with it again and again.
"Now this is a totally brain damaged algorithm. Gag me with a smurfette." -- P. Buhr, Computer Science 354