I always find it slightly amusing how there's remarkably few forms of power generation that don't eventually boil down to "use water/air/steam to make a turbine spin".
We're their pet project, why would they invade?
Or if we let off some earth mammals the beasts would be like, you know what, humans, take me and my descendants ten/a thousand generations down back to earth.
This sounds awfully knowledgeable about travel over multi-generational distances when neither you, nor I, nor any other human has ever done it. Maybe you're right that it's not what we would do, but how can you, I, or any human possibly know whether it's what an alien species would do?
It's a nice fantasy to think you can zip back to the home planet after prancing around the galaxy making discoveries and reporting consequential and timely information back home.
Second, you have a very anthropomorphic perspective built in to your thinking. What if they had lifespans measured in centuries or longer? What if they had radically different views of life and death and generational cooperation? Alien life is, by definition, alien. It’s hard to say what would/wouldn’t be true.
What? How is it possible to trade intercontinentally without there being a colony to trade with first? that makes no sense. One does not go to a deserted island to do trade, with whom, the birds?
If anything, this is the commenter that is being more careful not to entertain familiar science fiction presumptions and is exhibiting the discipline that you're asking for.
> If anything, this is the commenter that is being more careful not to entertain familiar science fiction presumptions and is exhibiting the discipline that you're asking for.
I really don't understand why you think this.
(Good thing ʻOumuamua missed. Better luck next time, chumps!)
Our current model of physics is barely a few hundred years old. We’re talking about a civilization that’s potentially hundreds of thousands of years ahead of us.
Yes, there is a possibility we will learn more and there are other pathways, but at the moment, that is fantasy, so it would all be speculative.
It also assumes similar moral and cognitive processes of what to do when encountering another planet's life, neither of which must hold true for a society or species to become spacefaring. Likewise, an alien's AI probe could be effectively immortal and that would drastically shape its opinions on a return trip.
Or maybe they're intergalactic mayflies with innate knowledge for reaching orbit or relativistic speeds but they die each day and a new generation takes over tomorrow. All distances are suicide missions, even trips across their own planet. It would totally normalize multigenerational trips.
I think it's short sighted to make any assumptions of human similarities when it comes to first contact. Cephalopods have independently developed significant intelligence in parallel here on Earth and they might as well be aliens to us despite a common evolutionary ancestor way back. A completely independent evolutionary path leading to intelligence could be incredibly counter to our expectations.
Speaking of cephalopods, do they seem less aggressive than other species? Have they gone vegan?
Is it more or less likely the species that goes vegan wins the race? And even if they did it would mean that they had to subdue a more aggressive species. In other words, pacifists cannot unilaterally (en)force peace.
For the traveler's frame of reference interstellar travel with current technology is within reach of single human lifespans if you're fine with a one way trip (and extreme cost without an expected payoff). If a species lucked out with some right-sized planets and orbital arrangements they could end up with a great gravity slingshot by happenstance that drastically reduces their energy needs in space.
The awareness of the tyranny of the rocket equation again assumes human sized likeness of aliens. If human-like intelligence arises in ping-pong ball sized beings on a low gravity planet they could have a much easier time than we do escaping their planet and physics would be on their side for extreme-G launches that would otherwise be fatal to us.
So much discussion about aliens is hinged on them just being a copy of us but located somewhere else. It doesn't take a ton of imagination to envision plausible and entirely different starting scenarios that enable greater success in space travel without inventing new physics or exotic engineering.
Invasion does not mean prejudiced extermination. If they ignored us as we might ignore insects when we discover new habitat then, yeah, I’d want to keep them from coming.
Interesting times ahead
Solar isn't less steam and less engine, it's literally just solar, whereas everything else but geothermal and nuclear is solar with more steps. Natural gas and oil is just solar stored in paleo compost.
I need to go hug my wife and children
I guess, if a species used a Dyson sphere for so long, they will certainly have colonized other solar systems, which each have their own star to milk.
Large scale HUGE capacity electricity storage is a LOT further away than a lot of people and interests are willing to... well.. as we see in europe.. allow for. We are going ahead with the first half of a system that isn't even complete in theory.
The biggest open question with grid storage is which of the many competing technologies will come out on top.
I see what you did there. I feel the same way, though. It feels primitive. But it’s what we’ve got!
https://solarsystem.nasa.gov/missions/cassini/radioisotope-t...
You can also do hobby-level usage like charging a cell phone with a candle.
"Though most commercial panels have efficiencies from 15% to 20%, researchers have developed PV cells with efficiencies approaching 50%."
"Both nuclear and coal plants show a range of efficiencies. Nuclear plants currently being built have about 34-36% thermal efficiency, while one of the new reactor designs boasts 39%. In comparison, new coal-fired plants approach 40% and CCGT plants reach 60%."
For PV, a higher "efficiency" means less land is used for a given nameplate power output. Desert land is not in noticeably short supply, though.
Or it might mean that PV is economically feasible in high-latitude or chronically cloudy areas.
A weir way uphill with a penstock and Pelton wheel could do better than the old mill, but both depend on landform features with limited distribution. If you needed twice the power, you would be stuck. But you can put out more panels.
Even in my relatively wet and grey corner of the world, I'm confident that if I spent $X on PV vs hydro, the PV would produce more electricity and require less maintenance.
PV/wind turbine efficiency and Rankine cycle efficiency are basically entirely different concepts physically and economically. Highly efficient rankine plants might turn 35% of the potential energy of expensive nuclear/coal fuel (which costs money) into electricity. In the process they produce waste heat and waste (dealing with those things is typically kicked down the road). Solar turns 20% of something that is free (being pointed at the sun modulo land use) into electricity with zero waste and zero additional waste heat. How is that inefficient (even if it were half that)? You can and should say lots of things about scale or nighttime but none of those have to do with prime mover efficiency.
Now consider economic efficiency. The denominator of economic efficiency for solar/wind is financing charges and the numerator is multiplied by a lower capacity factor whereas for everything else the denominator is financing charges plus fuel costs. Fuel costs are expensive and boom/bust volatile creating huge economic uncertainties. These uncertainties increase financing charges further reducing economic efficiency. This is before you get to waste or waste heat.
I don’t think 100% solar is a realistic option but neither are baseless claims of inefficiency.
> I don’t mean to be rude, but to say this without qualification is essentially baseless ignorance or lying.
Your own words can be used back at you.
(Not agreeing with GP, but your zeal in rebuttal falls victim to your own accusation)
Despite the 'but', I don't think you are disagreeing with your parent (who I took to be saying that they found it slightly amusing that we haven't discovered any more efficient ways to turn heat into electricity). If you meant that steam turning a turbine is the most efficient way that we know to turn heat into electricity, then it seems that you're saying the same thing as your parent, and it's not clear what 'just' adds. If you meant that it's the most efficient way that exists, then, first, I wonder how you know; and, second, I think that far from this being 'just' anything, it's pretty remarkable that we stumbled on the literally most efficient possible way so early in our history of working with electricity!
Saying the best way we know is the best way we know is vacuous. Nothing about steam is especially good except that water is cheap. It was cheap before, and still is. Its problems are problems we have learned to live with.
But it costs more than wind or solar, even with free heat. So it is a dead end.
You are right; I missed "that we know". That is entirely my mistake. But then it seems to make gridspy's comment rather content-less.
If someone says "I always find it slightly amusing how there's remarkably few forms of power generation that don't eventually boil down to "use water/air/steam to make a turbine spin".", then what does saying "it's just because that is the most efficient way we know" contribute? The 'because' suggests some justification, but it appears just to be re-stating what it's justifying. A re-statement can be valuable, but combining it with 'just' seems to be dismissing an observation that I, at least, found interesting enough not to dismiss, even if it is 'just' a description of existing facts.
So what I thought I was contributing here was an explanation of why we like steam and turbines so much.
I'm pretty sure that steam, turbines, etc have a big efficiency loss. Like you guessed, I meant "the best way we know of to do it at industrial scale now."
Edit : solar don’t involve having a Dynamo spinning.
Since I can't imagine any easy way to have produced that as a typo, you may like to know that the spelling is actually 'rhetorical' (no accent in English, despite 'rhétorique' in French).
It’s a « us » phone born and raise in the US. But I fed him so much French that he is unsure about things.
I let it happen. Accent are fun.