I don’t think it’s inevitable, I just think that given the millions/billions/trillions/even more of worlds out there, it should happen a lot more than once. (Exploration of Europa and Enceladus will give us 2 additional data points.) I doubt that we are alone, though I’m open to evidence to the contrary. I can imagine evidence to the contrary, once we figure out the emergence of life on this planet in greater detail.
Dyson spheres: it is indeed interesting that we have found no evidence for Type III Kardashev civilizations. Or Type II for that matter. But honestly, our civilization is far too young to make definitive conclusions about least-cost technological solutions 10,000 or 100,000 years in the future. Aristotle invented systematic intellectual inquiry less than 2500 years ago. Modern physics dates to Newton - less than 350 years. Finally we’ve had a little over 150 years of post- Maltusian economic growth and technological development. 150 << 1000 << 10,000 << 100,000 << ???. Back in 1023 an optimistic monk might have anticipated an absolutely awesome system of canals, neatly bypassing the difficult parts of any river. It’s much less clear that he would have anticipated the increasing significance of better roads (relatively) and bridges after 1200. Never mind horseless carriages.
Fermi Paradox: Similar argument. I would guess that there might be a few automated alien miners in our asteroid belt, built to create space exploration infrastructure. Because robot probes are cheaper than meatsack probes. But there might be even less expensive technologies involving eg remote viewing, or other approaches sufficiently advanced to make current research wholly pointless and probably ridiculous.
Right, but drop said monk in a city, or anywhere with a clear view of human habitation, and he would appreciate the evidence of a TI (terrestrial intelligence). And that’s exactly the point. We don’t see anything, period.
Monk couldn’t perceive alien intelligence in the sky any more than we can. Sure we have orders of magnitude better devices. But what they can rule out is… modest. Thread: SETI research: what can we now rule out?
Your point was that a monk couldn’t imagine modern-day tech. But whether he could have conceived of it is irrelevant to whether he would notice, say, a shopping mall as something unlikely to be of natural origin.
Likewise, we don’t have to predict in advance any kind of megastructure or noisy tech an alien species might make to observe the existence of one.
Whoever wrote the last post of that thread absolutely nailed it
Assuming that an advanced civilisation does not develop any game-changing magic tech, I would absolutely expect to see Dyson spheres and other megastructures in the sky, because they would be so useful. A Dyson sphere would deliver well over a trillion times as much energy to an advanced civilisation as we currently use on Earth;that would allow a potential population of quintillions of human-equivalent entities, or maybe a single entity quintillions of times as capable as a single human.
There are bigger possible megastructures even than the Dyson Sphere; Paul Birch suggested that the entire mass of a galaxy could be concentrated into a structure a light year across, called a ‘supraself’. This would reduce the latency of signals between the component parts from a hundred thousand years to a single year, allowing some consistency across its diameter (like Birch, I’m making the fairly reasonable assumption that faster-than-light-communications are not possible). Notably, the deep gravity well of such a structure would affect the local flow of time significantly, making time pass much more slowly towards its centre.
We don’t see any of these fantastically large megastructures anywhere in the universe, so it seems likely that fantastically advanced civilisations don’t exist, or maybe they have some other ways of existing that are invisible. Perhaps they prefer to create pocket universes and live in those, or maybe they can somehow inhabit the cosmic foam of the vacuum state; we probably wouldn’t see them in this case, although even vacuum state civilisations would surely be subject to the laws of thermodynamics. Any civilisation that uses lots of energy would be visible by its waste heat.
What exactly is it about our planet that is “unique”.
What exactly is it about our planet and our solar system makes Earth so unique that it can’t be duplicated in the trillions of other galaxies out there?
What’s so special and unique about a winning lottery ticket?
There are many steps between soup of organic chemicals and technological civilization, and we don’t yet know how (im)probable what happened on earth was.
Well, there is plenty of energy available, in sunlight; the sun produces as much energy as 91 billion megatons of TNT per second. But in order to collect that energy, one would need an already completed Dyson sphere. So it is a logistical problem, rather than a lack of energy.
To make a Dyson sphere you have to start small, and build increasingly large arrays of power collectors over time; this would be an exponential process, so there would be little progress at first. Maybe most civilisations just get bored waiting for the process to speed up.
Exactly, and bear in mind that a Dyson sphere is probably not the likely form factor (a solid shell or ring is dynamically unstable); a Dyson swarm is stable.
And if you’re building a swarm of energy-collectors, you don’t need to save up sufficient energy to launch all the collectors in one go – as soon as you place even one there you start being able to harness vast energies.
Life signs possibly found in the atmosphere of a planet 124 ly from Earth
ABSTRACT
The search for habitable environments and biomarkers in exoplanetary atmospheres is the holy grail of exoplanet science. The detection of atmospheric signatures of habitable Earth-like exoplanets is challenging due to their small planet-star size contrast and thin atmospheres with high mean molecular weight. Recently, a new class of habitable exoplanets, called Hycean worlds, has been proposed, defined as temperate ocean-covered worlds with H2-rich atmospheres. Their large sizes and extended atmospheres, compared to rocky planets of the same mass, make Hycean worlds significantly more accessible to atmospheric spectroscopy with the JWST. Here we report a transmission spectrum of the candidate Hycean world, K2-18 b, observed with the JWST NIRISS and NIRSpec instruments in the 0.9-5.2 μm range. The spectrum reveals strong detections of methane (CH4) and carbon dioxide (CO2) at 5σ and 3σ confidence, respectively, with high volume mixing ratios of ∼1% each in a H2-rich atmosphere. The abundant CH4 and CO2 along with the non-detection of ammonia (NH3) are consistent with chemical predictions for an ocean under a temperate H2-rich atmosphere on K2-18 b. The spectrum also suggests potential signs of dimethyl sulfide (DMS), which has been predicted to be an observable biomarker in Hycean worlds, motivating considerations of possible biological activity on the planet. The detection of CH4 resolves the long-standing missing methane problem for temperate exoplanets and the degeneracy in the atmospheric composition of K2-18 b from previous observations. We discuss possible implications of the findings, open questions, and future observations to explore this new regime in the search for life elsewhere.
A DNA test shows that this ‘alien’ contains some human DNA, but a whole lot of bean DNA. It seems to be a figurine manufactured from some human remains, and a bunch of bean paste.
A Hycean world is a world with a vast, deep, warm or hot water ocean and a hydrogen atmosphere. The oceans on such a world may be hundreds of kilometres deep. I think we can safely say that we don’t really know what the geochemistry of such a world might be like in detail.
However the existence of such a deep, hot ocean would probably rule out any kind of life we are familiar with. I find it difficult to imagine how abiogenesis might occur on such a world, but since we don’t know how abiogenesis occurs anyway, that may not be a problem.
Life may sometimes arrive via panspermia from elsewhere, so the problem would not even arise in that case.
… and then congress might stop funding, b/c that might win them the next elections …
half in jest, half not …
I am not sure if those huge looooong-term projects CAN be brought to fruitition in a democracy (pls. don’t read any autocracy-fandom into my Q. ) - as tactical stupidity might trump (hey!) what is right to do long term…
