Live data from Hacker News

Have we already been visited by aliens?

newyorker.com

111–120 of 366 posts

Re: Have we already been visited by aliens?

#111
post #90

Earlier quoted context omitted.

There seems to be a giant mismatch about what side is open minded. People who think its most likely aliens think it’s closed minded to assign that low probability, presumably because we’re this tiny corner of the universe. People who think it’s most likely not aliens Think it’s closed minded to assign everything else low probability, presumably because aliens are a tiny corner of everything else. Is it a misapplicati…

I thought the idea that there are gazillions of advanced aliens has been pretty much disproven by the fermi paradox. If there are gazillion, at least one out of all the diversity out there should have already colonized the entire galaxy and evidence should be plentiful.

A possible chink is that civilizations just don't do that -- carpet colonize the whole galaxy, or fill it with their probes to the extent that we seem them all over the place. The Fermi paradox relies on material (probes, colonies) and light (signals).

With the material explained away, the lack signals is much easier to explain in that we haven't listened long and we can only hear very loud signals. (Or maybe advanced civs don't use light and use gravity waves or tachyon beams or whatever, but you don't even need to go that far.) The only way we hear a signal is if it's:

1. loud (high energy) and aimed directly at us, like a tight beam

2. EXTREMELY LOUD and aimed everywhere, isotropically

1 is unlikely since they'd have to know where we are; 2 is unlikely since you're talking about an insane level of energy. If it's the case that civs don't seem to be making Dyson spheres or harvesting whole galaxies for energy, being able to throw around that kind of power is prohibitively expensive. In both these cases, the inverse square law applies (for every unit x of distance, the light's x² less bright). Ironically, that means we're more likely to detect signals from an improbably close civilization (like 4 light years next door, in Alpha Centuari), than from farther away -- and even then, by a chance sweep of an umodulated asteroid scanning beam[0] or something, if we happened to be paying attention at the time.

0: https://en.wikipedia.org/wiki/BLC1

Re: Have we already been visited by aliens?

#112

> Loeb, though, explicitly rejects the Sagan standard—“It is not obvious to me why extraordinary claims require extraordinary evidence,” he observes—and flips its logic on its head: “Extraordinary conservatism keeps us extraordinarily ignorant.” So long as there’s a chance that 1I/2017 U1 is an alien probe, we’d be fools not to pursue the idea. “If we acknowledge that ‘Oumuamua is plausibly of extraterrestrial-techno…

There seems to be a giant mismatch about what side is open minded. People who think its most likely aliens think it’s closed minded to assign that low probability, presumably because we’re this tiny corner of the universe. People who think it’s most likely not aliens Think it’s closed minded to assign everything else low probability, presumably because aliens are a tiny corner of everything else. Is it a misapplicati…

Their best future course is to stop sniping at one another.

It is possible that it's aliens. It is possible that it's not. We don't have enough evidence even to estimate probabilities, so anything further is pure speculation. Speculation is a look that wears no better on conservatives than on radicals.

There is hardly a field to be found where young radicals are not promoting evidence for what the tenured consider anathema, waiting for the latter to retire or die and get the hell out of the way. As Max Planck said, "Science advances one funeral at a time."

It is common to insist that the right idea wins in the end, but there is no reason to believe it: every case you can cite in its favor amounts to confirmation bias. The frequency of such examples that first languished for decades, with the original proposer driven from the field, would properly make us suspect that the majority of their also-correct peers remain unvindicated, however many false leads have been exposed. (Hypotheses promoted by women driven from a field make a rich vein of ideas to vindicate.)

Loeb is right about one thing: the notion of "extraordinary evidence" is very destructive. Evidence is evidence. It is always easy to make greater demands on evidence you don't like than on evidence you do, and always easy find excuses to discount evidence incompatible with the consensus of the moment. Every field, to be considered legitimate, should maintain an officially taught compendium of "damned facts", evidence that seems to be incompatible with one or more leading theories. Even when a consensus theory is largely correct, the damned evidence will be the basis of any progress.

Nature doesn't play favorites: it is possible for a consensus theory and all its challengers to be wrong. Evidence against one of the latter is not evidence in favor of the former.

Re: Have we already been visited by aliens?

#113
post #85

Earlier quoted context omitted.

Imagine a race of ultra-advanced aliens were to give us technology that keeps us not only alive indefinitely, but robust and healthy, without disease. Just that one piece of technology. Not even weird weapons like antimatter bombs, etc. Do you think humanity would suddenly come together in understanding and peace to explore the stars and advance ourselves... or do you think people who already have enormous wealth and…

Well no, but people would be robust and healthy, without disease. And IMO, that's a positive even if all our other failings are still there.

For the individual, yes, but for society? Death is nature's term limit. Without it we'd be under a Pharaoh with bronze-age ethics.

Re: Have we already been visited by aliens?

#114

Earlier quoted context omitted.

That's one of the biggest problems I have with Star Trek. If we were literally gods by comparison to some fledgling species, the only ethical approach would be to elevate them and cure their diseases and advance their knowledge as quickly as humanly possible.

Already done for indians. Impossibility of FTL travel just saved all life in universe from you.

What wiped out most of the Indians was plague and genocide while seizing territory and resources.

I don't think plague would be an issue - viruses require proteins to be similar to attach and reproduce, and bacteria require nutrients to be the same. And as for resources? Asteroid mining will get you more water, minerals and metals.

But territory - terraforming might be really difficult or take too long. If aliens need an oxygen/CO2/nitrogen atmosphere and liquid water, Earth could be tempting, even if the plant/animal life is useless to them.

If territory isn't an issue, maybe we'd just be friends or anthropological curios.

Re: Have we already been visited by aliens?

#115
post #86

Earlier quoted context omitted.

Ridiculing scientists for plausible hypothesis seems very unscientific.

This is very common in science. New theories are usually rejected and ridiculed until/if they develop enough evidence behind them to sway people. Some careers are destroyed. Some scientists are only vindicated posthumously. The process can take many decades. Scientists, like most humans, are not that open-minded and are subject to the same group-think blind spots. I think if we could get better at being open-minded a…

And they are careerist...

My Post-doc colleague during my PhD@MIT was explaining this trick he does to get his system working that he never publishes (one very small step of 100 steps). He was concerned that if he published the step, it would hurt his chances at getting a professorship.

It’s exactly the same logic behind why code is not published.

Because ethically you can ‘hand wave it away’ as obvious to other experts and not worth publishing.

Re: Have we already been visited by aliens?

#116

Tangential to the article, but I’m not sure why more isn’t mentioned about what I consider to be the most likely reason we haven’t been visited by aliens: they probably exist somewhere due to the sheer size of the universe, but the speed of light is indeed the fundamental limit to classical information transfer as our current understanding of physics predicts, and therefore we are simply too far away from any sort of…

I don't find the argument that distances are too great for intelligence to meet particularly convincing. At its core lies unjustified extrapolation that the ratio of average lifespan to typical interstellar distance - a pure accident of Earthly biology - somehow extends to the whole universe.

The key quantity on which the argument hinges is

    T * c / D
where T is the average lifespan of the intelligent being in question, c is the speed of light and D is a typical separation between stars in a region of interest.

In our stellar neighborhood there are about 0.004 stars per cubic light year [1], so if we choose to measure D as the reciprocal of the cubic root of stellar density then D is about 6.3 light years which is of the same order of magnitude as the distance to Proxima Centauri (~4.2 ly). This quantity varies somewhat, e.g. global clusters have about 0.4 stars per cubic parsec [2] which is more than 0.01 stars per cubic light year for D of 4.4 ly.

In case of humans, T is about 79 years. We don't know anything about any alien lifeforms, but even among lifeforms on Earth T varies significantly. For example, Bowhead whales can live more than 200 years [3]. Traveling 4 ly at 5% of the speed of light is a possibility for such creatures. Moreover, entities with artificial intelligence could live (function?) significantly longer. Possibly forever.

[1]: https://en.wikipedia.org/wiki/Stellar_density

[2]: https://en.wikipedia.org/wiki/Globular_cluster

[3]: https://en.wikipedia.org/wiki/Bowhead_whale

Re: Have we already been visited by aliens?

#117
post #96

Earlier quoted context omitted.

The most recent event that comes to my mind is the lead up to the discovery of H. pylori causing gastric ulcers.

Tectonic plates was another big one.

This is a current fun topic with some controversy related to tectonic plates: do solar flares cause earthquakes?

https://astronomy.com/news/2020/07/powerful-eruptions-on-the...

Re: Have we already been visited by aliens?

#118
post #42

Earlier quoted context omitted.

Yea, the actual fallacy is thinking you must identify what something is before you have enough information. 1I/2017 U1 is an unknown object and that’s perfectly ok. It didn’t display any radio signals, unusual thrust, or extreme velocity requiring it to be an alien probe. But, that doesn’t prevent it from being a probe either.

While it’s true that it didn’t produce any detectable radio signals, it have an unexplained force acting on it. It was this acceleration away from the sun that spawned the theories of undetected outgassing or light pressure. As for “extreme velocity”, that’s a bit a canard. It’s traveling at interstellar speeds, and humanity has already has five interstellar probes today. Now none of these indicate that it’s probe —…

I chose unusual as it had thrust consistent with comets.

After ruling out solar-radiation pressure, drag- and friction-like forces, interaction with solar wind for a highly magnetized object, and geometric effects originating from 'Oumuamua potentially being composed of several spatially separated bodies or having a pronounced offset between its photocentre and centre of mass, we find comet-like outgassing to be a physically viable explanation, provided that 'Oumuamua has thermal properties similar to comets. https://pubmed.ncbi.nlm.nih.gov/29950718/

PDF: https://csnbiology.org/rw_common/plugins/stacks/armadillo/me...

PS: At to extreme velocity, something large traveling 0.1+ c or even 0.01c is very likely to be aliens. This was fast, but a long way from those kind of speeds.

Re: Have we already been visited by aliens?

#119
post #105
post #90

Earlier quoted context omitted.

I thought the idea that there are gazillions of advanced aliens has been pretty much disproven by the fermi paradox. If there are gazillion, at least one out of all the diversity out there should have already colonized the entire galaxy and evidence should be plentiful.

According to the Chinese science fiction author Liu Cixin the Fermi paradox is solved by the certainty that if an alien civilization announces its presence to the rest of the universe, one of the gazillions of other advanced alien civilizations is sure to destroy it. So they keep quiet.

That would imply the laws of physics somehow dictate the self-manifestation or creation of intelligent clouds of elements (e.g. humans) who by their vary quantum waveform / nature are violent and want to destroy other clouds of elements even if the cost involves harvesting energy from your only local star.

Re: Have we already been visited by aliens?

#120
post #105
post #90

Earlier quoted context omitted.

I thought the idea that there are gazillions of advanced aliens has been pretty much disproven by the fermi paradox. If there are gazillion, at least one out of all the diversity out there should have already colonized the entire galaxy and evidence should be plentiful.

According to the Chinese science fiction author Liu Cixin the Fermi paradox is solved by the certainty that if an alien civilization announces its presence to the rest of the universe, one of the gazillions of other advanced alien civilizations is sure to destroy it. So they keep quiet.

The books and all are nice but the Dark Forest Theory doesn't hold agains much scrutiny. Among other reasons because if that were true we would be already dead.

https://www.youtube.com/watch?v=zmCTmgavkrQ

Post reply on HN