i feel like its premature to discard the possibility of FTL travel and it should be taken into account when discussing the fermi paradox. if FTL travel / FTL communications exist, we have no means of detecting that
The Fermi paradox revisited: Technosignatures and the contact era
341–350 of 353 posts
Re: The Fermi paradox revisited: Technosignatures and the contact era
#342Earlier quoted context omitted.
Here's an amusing thing. Even if they were within Jupiter's orbit and decelerating and pointing straight at us, we wouldn't be able to detect them. Nuclear bombs produce a fireball here on Earth. In the first microsecond when the explosion actually happens, they produce gamma rays and X rays. The atmosphere is opaque to those rays, which is to say, it absorbs them. Their energy is enormous, so the part of the atmosph…
Rocket propulsion benefits from directional discharge. Project Orion lead to the investigation prospects for nuclear shaped charges , in which the blast is highly directional. The concept was developed further in the colourfully-named "Casaba-Howitzer": https://en.wikipedia.org/wiki/Casaba-Howitzer > Odds are reasonably good that any space-faring civilisation would create similarly directional reaction devices for sp…
Nowadays there are satellites with omnidirectional gamma-ray detectors to detect gamma-ray bursts, so that optical and other telescopes can be turned on them.
Its a question of if these would be sensitive enough, but I think we can only expect the detection satellites to improve over time.
Re: The Fermi paradox revisited: Technosignatures and the contact era
#343Earlier quoted context omitted.
> It's very likely life exists elsewhere How can you support this statement? It requires that Origin of Life is sufficiently probable, and we cannot conclude that from the known evidence (that life originated early on Earth is not sufficient, as we don't know how long the conditions suitable for OoL persist in a new solar system.)
well, for some values of “very likely”. ;) I base it on extremophiles. Life exists in volcanic vents and freezing waters. So it seems possible that at least microbial life exists somewhere else in the universe. Either way, “is/has there been at least microbial life on Venus, Mars, or Jovian moons” seems like a solvable question in the next 100 years or so. The conditions for intelligent life seem much more narrow.
That doesn't say life is likely to arise. It just says that life as we know it can, once it arises, evolve to exist in some extreme environments.
Re: The Fermi paradox revisited: Technosignatures and the contact era
#344Earlier quoted context omitted.
No, he was rightly pointing out that your "there probably is" statement was bullshit, not supportable from the evidence.
I think AlbertCory was saying that to assign specific probabilities, as the Drake equation does, is BS. To say "there's probably life out there", in a vague, speculative sense of probably, is a different sort of thing.
Even then, he is putting bounds on probabilities. Specifically, that the chance that life arises around a random star is >> 1/(number of stars in visible universe).
The argument is really just trying to elevate vague and incorrect intuition beyond anywhere it has any right to be. It comes from not understanding just how serious a bias can be introduced by observer selection.
Re: The Fermi paradox revisited: Technosignatures and the contact era
#345Earlier quoted context omitted.
"Bullshit", as I use the term, is misrepresentation of the state of your knowledge by confident assertions you can't back up with evidence. The statement is precisely that, bullshit.
oh, lighten up. No one is getting all oracular here. I have my opinion, you have yours. "Probably" is not a "confident assertion" at all.
"Probably" is a quantitative assertion. If you want to be properly vague, use "possibly".
Re: The Fermi paradox revisited: Technosignatures and the contact era
#346The Fermi paradox is good for a nice chat at a party. But it's not a paradox at all. Imagine there's an alien civilization in our galactic neighbor Proxima Centauri. How would we know they are there? To make it more plausible. Let's say we figure out a way to send a space probe to Proxima Centauri. How do we communicate with that probe? Easy, you say, just like we communicate with the Voyagers: they point a reasonabl…
Your calculation is likely wrong. See, you can build a laser in a spectrum not generally emitted by stars, and point directly to another star system. You dont need much power, yes, perhaps some terawatts, but it can be pulsed, total energy would be low. And getting a low power signal doesnt means its impossible to detect, but that the bandwidth is short. Instead of 200 bits per second, you would get 1 bit per hour. B…
OP is saying how would we detect a civilisation unknown to us, and for who we are also unknown. A system such as you describe would only be practical for a civilisation trying to communicate with a known counter-party. Otherwise which stars do you target your laser on, and for how long?
Let’s say the Centaurans developed advanced technology 100 million years ago, would they beam this signal at our star for all 50 million years until we happened to evolve? Why our star system, why not any of millions of others? As this system is so directional each detector could only monitor one star at a time. How many do we build, and which stars do we point them at, and for how long?
For direct communication with an established target this would be fine, but as a broadcast system it’s way too target specific to work at galactic scale.
Re: The Fermi paradox revisited: Technosignatures and the contact era
#347The Fermi paradox is good for a nice chat at a party. But it's not a paradox at all. Imagine there's an alien civilization in our galactic neighbor Proxima Centauri. How would we know they are there? To make it more plausible. Let's say we figure out a way to send a space probe to Proxima Centauri. How do we communicate with that probe? Easy, you say, just like we communicate with the Voyagers: they point a reasonabl…
Just want to point out the currently known composition of the universe: ~5% matter. The stuff you and I are made of. Most of this is H and He though, bit of Li in there too. And it's all mostly burning in a star. Like, 99.99999% of it. ~25% dark matter. We know little about it. We do know that it falls down though and doesn't like to touch other stuff. But that's kinda it. ~70% dark energy. We know pretty much nothin…
Dark matter appears to be a very weakly interacting fluid, completely unsuitable for developing any kind of structure at the local level. Dark energy is, well, energy. Also incapable of local structure. I’m afraid conventional matter it is.
Re: The Fermi paradox revisited: Technosignatures and the contact era
#348Earlier quoted context omitted.
So begin with a sequence of 1 1 1 1 1 1 1 1 1 1. That establishes a baseline cadence of minutes, or hours or whatever. A clock signal if you will. Then switch to primes. I think anyone looking at that kind of message will figure it out eventually. It can't be mistaken for a natural occurence.
> So begin with a sequence That is the trick that I was calling out. The intervals are reals, and cannot be made into a sequence. Beginning with a sequence is even worse; what is in evidence (for the aliens) is a set of real intervals. That's what the aliens have to begin with. Now explain how they get to primes.
If the precision between the intervals is good, how can you not get to primes?
Of course the intervals would be real, but there would be a very discernible pattern.
It would stare you in the face, or what am I missing?
Re: The Fermi paradox revisited: Technosignatures and the contact era
#349Earlier quoted context omitted.
You're looking at the sky and you see a bright and otherwise unexpected signal. Then you see it again, some time later. You write that time down as T_1. You don't know of any astronomical phenomena with period T_1, so you wonder whether this could be a weird rare event. Then you see it again, spaced by T_2 this time, and you start to wonder whether it could be a purposeful signal. Then T_3 etc. How could they be link…
> so maybe it is a sequence At that point, you introduce the assumption that the interval is quantized. Up until then, you're dealing with an arbitrary period of time, which is a real, and can't be made into sequences. Once you have sequences you have integers, and so you can have primes. But you can't just switch from reals to countable numbers without explanation, and then say that two reals can be relatively prime…
I disagree. Sequences of reals are still sequences. So maybe hypothesis one has nothing to do with integers, maybe it's that the intervals are increasing geometrically. You're still going to take ratios and and start having suggestive numbers fall out. "can't just switch ... without explanation". The point is that this putative alien observer would be looking for the explanation. Maybe the first few explanations they come up with are the wrong ones, but they are trivial to check. It's not like it's a research project to reject the Fibonacci hypothesis.So you would still have the right answer on day one.
Re: The Fermi paradox revisited: Technosignatures and the contact era
#350Earlier quoted context omitted.
The author raises an interesting question in his notes - human nations & races have for much of human history distrusted each other & gone to war. And yet we broadcast our location and welcome out into the cosmos assuming that alien species will be benign and friendly!
IMO that fact is actually a pretty strong reason to doubt the dark forest hypothesis as a serious explanation for the lack of observable aliens. If we've broadcast ourselves to each other for thousands of years and now even to the universe, why should we expect that every single other civilization out there is consistently doing the exact opposite?
Arguably we've only been broadcasting outwards for something like 50 years, so the message hasn't gotten that far yet.
There was a plot element in the book about using a technique to broadcast a message more strongly than terrestrial antennas alone.
A spoiler alert another plot element in the book was that it wasn't just the one way broadcast, but a response & counter-response that allowed distant aliens to determine distance and direction.
So I wouldn't quite say its disproven.