given the age of the Universe and the relatively short time it would take for an advanced civilization to spread across the Milky Way Galaxy (650,000 years, by Hart’s estimate), Earth should have been visited by an extraterrestrial civilization (ETC) by now.
It took humans 30,000 years to cross the Atlantic. Using modem propolsion systems, it takes us two years to get to Mars and 40 to reach the edge of the solar system. This seems like an extremely generous estimate considering the Milky Way has a 50,000 light year radius.
I’m as bullish about extraterrestrial life as anyone, and I think a fuller survey of even just the current Solar System has potential. But I have no idea how you get a full galactic survey in so short a time, given what we know about the soft limits on speed of travel and communication.
By Tipler’s refined estimate, an ETC would be able to explore the entire galaxy in “less than 300 million years.”
That definitely feels like it’s more in the ballpark. But, again, it presumes a certain amount of steady cartography by the hypothetical fleet of Von Neuman probes.
There’s a Sci-fi series called The Bobverse that explores the idea of a sentiment fleet of Von Neumans exploring the galaxy, and the various trial and tribulations involved. One point it discusses is that even with a saturation of probes, you don’t get real time communication. So even in a hypothetical universe where alien life did exist and survey earth, what are they odds they’d be watching us at the moment of our development. What would an alien AI be looking for and what would it do when it was discovered?
We could still be too primitive to bare noticing. Or we could be living in between blinks of an alien camera that only reports back every 1000 years.
As we look out at the cosmos, we could be looking at things we don’t understand. After all, what does a star surrounded by a Dyson Sphere look like to a telescope that is searching for glimmers of light, heat, and gravity? SETI is operating purely on conjecture. That’s assuming alien civilizations are even capable of creating these hypothetical superstructures. Or that the structures would function as we intuit.
At some level, I have to question if we know what we’re looking for. Because so much of this feels like we’re searching for humans deep in space. Perhaps the reason we can’t find aliens is that they are simply… too alien.
No, rare intelligence and to a lesser extent rare earth remain as convincing as ever. Potentially habitable does not mean life sustaining, and given the lack of strong biosignatures on any of the examined near earth exoplanets, I’d say that there is indeed increasing evidence that life of any kind really is that rare, much less intelligence.
It is just absurdly hard to get conditions right for microbes to form on a reasonable timeframe is a solution after all.
All this time? What like less than 100 years looking only? That’s a blip on the cosmic scale. 100 lightyear sphere of our galaxy is what, less than 1%? With all the theories and possibilities of what’s going on out there, it’s way too rash to start theorizing like this in my opinion.
I haven’t seen the evidence of ‘water oceans’ out there that are about more than a few water ‘geysers’ spewing from below the frozen surfaces like our breaths on winter mornings.
Whenever I hear the words ‘water’ or ‘life’ in a message from NASA I think, ‘Hmmm… who stands to gain from this PR?’ (At least telescopes return great pix and -other, visible- evidence.)
In case anyone wasn't aware, nearly all space photos that you've ever seen have had their colours tweaked. It's standard practice in space photography. Nebulae and galaxies and planets aren't as colourful as they appear in photos. They do it either to make the features more obvious for study, or just to make them pop more to drum up interest in space exploration. Nothing wrong with it, just be aware that what you see isn't reality but an interpretation.
Really though, I don’t know why it never crossed my mind that the picture of Neptune was so… saturated. It’ll take a little bit to reconcile this new perspective of a “light bluish-green” Neptune. It’s just so jarring to alter a belief held since my childhood.
The latter, I suspect. That’s certainly how forming a neutron star works in the first place, because if a star gets so dense that it can form neutronium then the neutronium (which is far more dense than the core was before) can easily keep making more.
It’s a similar story with black holes. Get past the threshold at which it forms, and the process runs away and swallows the whole star.
If a quark soup is more dense than neutronium, then it would be fairly all-or-nothing
Wouldn’t be the first time and prolly won’t be the last time.
Jamestown.
Jamestowne is home to the ruins of the first permanent English settlement in North America.
104 settlers but only 38 survived
Despite writing describing cannibalism:
“Haveinge fedd upon our horses and other beastes as longe as they Lasted, we weare gladd to make shifte with vermin as doggs Catts, Ratts and myce…as to eate Bootes shoes or any other leather,” he wrote. “And now famin beginneinge to Looke gastely and pale in every face, thatt notheinge was Spared to mainteyne Lyfe and to doe those things which seame incredible, as to digge upp deade corpes outt of graves and to eate them. And some have Licked upp the Bloode which hathe fallen from their weake fellowes.”
Direct evidence of cannibalism at Jamestown, the oldest permanent English colony in the Americas was elusive until recently finding “bones in a trash pit, all cut and chopped up, it’s clear that this body was dismembered for consumption.”
This is freaking hilarious. I might buy this book just to read more of this:
“Imagine you’re stranded on the Red Planet with three crewmembers,” Seedhouse, a professor at Daytona Beach’s Embry-Riddle Aeronautical University wrote. “You have plenty of life-support consumables but only sufficient food to last one person until the rescue party arrives. What do you do?.. One day, while brewing coffee for breakfast, you realize there are three chunks of protein-packed meat living right next to you.”
… the biggest of the Mars explorers should sacrifice themselves first because they “both consume and provide the most food.” He went on to provide a “weirdly detailed look” at how to cut up one’s fellow humans if necessary.
“We don’t know where Seedhouse would fall in the buffet line because we couldn’t find his height and weight online,” the authors wrote, “and honestly we’re scared to ask.”
In “Survival and Sacrifice”… readers will also find… a photo of ten astronauts smiling in space alongside the caption: “In the wrong circumstances, a spacecraft is a platform full of hungry people surrounded by temptation. Is it wrong to waste such a neatly packaged meal?”
I used to think this idea was kinda silly and based on flimsy and handwavey justification, but then I saw a colloquium by a famous black hole physicist on it. Now I REALLY think this idea is silly and made up!
astronomy
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