I'm so fascinated (as an uneducated layman) by space and cosmology but honestly most of it's way over my head because with questions like this I inevitably get bogged down in philosophy. Like What is life? What is consciousness? What is intelligence? That's before we even start talking about the practical hurdles like communicating, navigating or traversing the huge distances when we don't even know why our models are so out of touch with our observations (dark energy). Two questions then. 1. From this side of the great filter. How likely do you think it is that we could permanently escape earth and survive/flourish? My guess given the current state of things is close to zero chance, but I'd love a more informed perspective. 2. From the other side of the great filter. What do you think the difference in intelligence/capabilities would be if there was ever contact? My gut feeling is it would be like an upside down bell curve or similar. Probability close to 1 that Civilisation A is vastly, vastly ahead of Civilisation B curving down to close to 0 where both are about equal, then rising again to close to 1 where B is ahead of A.
Almost 100% likely. We're at the point where asteroids and comets pose almost no threat, because we're developing the tech to nudge them enough that they avoid Earth. We track all the big stuff, and should have years of notice to prevent global catastrophe. In just another 20 years, if a large asteroid/cometary impact hasn't happened, it never will. Nukes? Even if Trump starts some serious shit, there'd still be some survivors, somewhere. Billions might die, but a few tens or hundreds of million might live, if not more. Eventually, they rebuild civilization, and it probably doesn't take but another few thousand or ten thousand years at worst, the blink of an eye on astronomical timescales. Similar arguments for an epidemic, whatever. Some people, somewhere, survive and go into subsistence until they can rebuild society. And society always wants to eventually expand into space. If we can avoid the billions-of-deaths-thing, though, yes please. The inverse bell curve idea sounds mostly right, but it supposes that the more advanced civilization wants to make itself known to the lesser, and I think that's probably almost never the case. Why would aliens bother us humans, at this point in our development? We would just try something dumb and end up hurting ourselves. If there is really some sorta galactic order, then there would be a set of criteria of governing who can hang. I guarantee you that we don't meet that criteria yet.How likely do you think it is that we could permanently escape earth and survive/flourish?
What do you think the difference in intelligence/capabilities would be if there was ever contact?
At this point in our evolution as a species, what incentive does another civilization have to spend the intensive resources it would take to make contact with us? We have nothing to offer, unless we ourselves (food, labor) or our planet are the resource. Otherwise, the only reason I see to make contact is because you can do it from a distance, but the communications lag makes that an endeavor that is unlikely to return a result in any biological being's lifetime, so why do it, and also, why risk calling in the guys who are likely to see you as a resource?
Hello, half-baked space person here. Of all the speculative answers on why another civilization would contact us: The flip side is our own (to extend the metaphor) child-like curiosity of the cosmos around us. Are we truly alone? What could we learn from other life (technologically, biologically)? Where are they at in their civilization's development? Is there evidence/ hope for us to come to a place of global unity or overcome existential troubles like climate change without great loss [actually the first link covers this too]? Edit: So both points I meant to link were from the same conversation. The link above would start at what I sought to answer. The start of Sagan's dialogue with Carson on the search for terrestrial life on that date: It touches most of the conversations and some jokes along this thread. Worth a fun, informative listen.What made this optimism nevertheless terrifying was the unknown of what the adults of the cosmos would be like. Would they be peaceful? Would they be so advanced that they would treat us as we treat a fruit fly or a rat, or a lab mouse, or even Laika the space dog? Would they treat us as food, the way we treat cows and pigs? Would they carry with them genocidal new diseases the way Europeans did to the Americas? Would they be the disease? Would they demolish the Earth to make way for a hyperspace bypass?
Clifford Simak's "Big Front Yard" of 1959 presupposes that in a universe of abundance, the only reasons to interact with other species are cultural. After all, if it's natural resources you need there are plenty of planets unbeloved by angry natives who don't want their water taken. The example from "big front yard" involves small mouse-like aliens who take a bunch of spare parts from a Yankee trader and pay him back by turning a black'n'white TV in for repair to color. He then discovers their "stargate" for lack of a better term and wanders out into the plains of interstellar commerce where he discovers that while humans have not invented antigravity, apparently we're the first culture to come up with coating things in different-colored pigments for purely aesthetic purposes. There's a later story from the '80s, the title, author and gist of which I cannot recall, but it was an archetypal "the aliens are among us" story with the argument that duh they're here for the culture. The only thing I do remember was the extremely poignant example of rabbits: the alien in the story explained that any number of races could look at a rabbit and produce any number of reproductions but to date, only one culture has come up with a "wascally wabbit." If you think back through the history of human exploration, minerals provide a short-term gain, biological specimens a slightly longer gain, but what we've gotten from exploration, over the long term, has been cultural exchange. It's undoubtedly anthropocentric to assume the same about an encounter with other species but really, the one thing we're likely to have that's unique to us is our culture.
Most audiovisual technology of the past 50 years has been advanced by porn. VCRs, video compression, cheap cameras, 3D, you name it. There was a need for cheap development of moving images so capitalism found a way. Capitalism usually finds a way. The philosophical answer to "what is consciousness" and "what is intelligence" is a question that can be discussed but from a pragmatic standpoint, the discussion is "can I take it or do I have to negotiate." Which, obviously, has a different answer when you're incommunicado with the bleeding-hearts of your nation. But it also drives a more pragmatic question that generally gets obliterated in all the philosophy: what is the economic case for space exploration? What need is being driven by launching billion-dollar probes at Mars? You can make one: NASA gives us prestige in the face of other nations that allows us leverage in international discussion. It also allows us to publicly try out new technologies that can be used for other (often less public) uses. By sending billion-dollar probes to Mars we are reminding the rest of the planet that we're number one. But this whole "asteroid mining" thing. Or "terraforming Mars." I mean... we have a dire need to terraform EARTH to the point where our CO2 levels are closer to habitable and not only is it going to be a lot less work to take our atmosphere from 400ppm to 250, we're already here. Culturally, this is what brought the Apollo program to a screaming halt: the USSR gave up, we lost in Vietnam and the country lost their appetite for giant extraplanetary boondoggles so inside five years we'd gone from 2001 to Rollerball and Logan's Run. SETI is so laughably un-useful that it's not even worth modeling. Planck's Law predates broadcasting yet we've had this romantic notion of little green men watching I Love Lucy since the dawn of television. SETI was entirely focused on the hydrogen band because obviously we broadcast everything everywhere all the time and it's the only place that isn't swamped and then lo and behold the minute we develop tight-beam communication we're looking for that now. The Drake Equation is bullshit and always has been because Frank Drake wanted time on a radiotelescope and the Navy wanted a justification. So Frank came up with seven stacked bullshit factors and said "look, coefficients" and the Navy said "great I just need something to put on the form." Hey, am_Unition I got one! Give me the energy requirements for a tightbeam visual signal from, say, Alpha Centauri B. I wanna be able to read morse code at night. We've got logarithmic energy density so I'm going to need to up the brightness an order of magnitude. Presume 100% efficiency of the laser/maser/whatever- how much energy is my tightbeam communication across a puny 4.3 light years going to consume? Bonus points if you give me a number for both red and blue wavelengths.Like What is life? What is consciousness? What is intelligence?
Yepperz. Realistically, it will "cost" governments tens of trillions of dollars to solve the climate problem. Over the next ten to twenty years, it will become glaringly obvious that we have no choice. When people are like, "HEY, send me to start terraforming Mars RIGHT NOW!", I wanna tell them, "OK, have fun! I'll be here. Maybe you'll get the bandwidth to email me before you die, but maybe not". I think NASA is probably realizing that any serious attempt to colonize Mars needs to be an international endeavor if it will ever have a chance of succeeding (/affording it). With a staunchly anti-globalist president, there's no good reason for NASA to broadcast that, because they also probably realize that they're gonna have to pull a Vatican and think on timescales of human generations from the get-go, so what's four or eight years? I've been trash talking a Mars shot since I got here. The public simply doesn't understand how many challenges there are to colonizing Mars, and unlike asteroid mining, there are essentially zero business incentives for sending people to Mars. That I can think of, at least. It's not hydrogen emission, it's emission generated when hydrogen bonds to hydroxide and makes water. Had to look it up, I was so confused, I thought "Why would SETI be looking at... Lyman-Alpha..?". I don't think targeting water is a terribly bad idea. Water has so many unique properties (yuge heat index, less dense in the solid phase than the liquid, relatively small temperature difference required for phase changes, should occur everywhere in the universe near a previous supernova that produced the Oxygen, etc.), and although it certainly might drastically narrow the types of "life", it seems like a decent start. I think I've said this before, but I wonder if there isn't something encoded into quasar outbursts, like if advanced civilizations ever systematically arrange matter to fall into the supermassive black holes at the center of galaxies. I doubt it's really possible to encode much on very short timescales, because the processes in the accretion disk and jets that create emissions are super turbulent and non-linear. Actually, we think the most common non-linear process energizing things there is probably magnetic reconnection (muh jerb), but anyway. The dots and dits could be days, weeks, months, or years-long, though, I guess. That'd be the best way to have an omni-directional signal, because you'd be modulating gamma-ray and relativistic particle fluxes, which are rare enough that your signal-to-noise ratio is muuuuuuch better than other wavelengths or lower energy particles, especially if it were coming from the center of your own galaxy. There are many many other considerations, though. Didn't know that about Drake and the Navy. I still maintain that the galaxy might be teeming with life, and there's not really a reason for them to bother us. Apparently there are plenty of solar systems with rocky, watery planets. There might be only a relatively small span in a civilization's development when they broadcast radio waves up into space before switching to neutrino beams or whatever. Think of it like a spherical shell of radio waves, and however many years they broadcast for, that's how many light years thick it is, and the radius of the shell is obviously growing one light year per year. The strength of the signal inside the shell decays as a function of 1/r^2; quite quickly, as the radius expands outwards. Ho boy, here we go. Pinging Devac for peer review. Like, with the naked eye? OK, you'll need an apparent magnitude of at least +6. Let's make it +4, because I don't want to voyage into the central Pacific Ocean to see this, I don't even wanna squint. We'll assume that the Alpha Centaurians (probably centaurs) have tuned their laser's beam divergence such that when it reaches us, the beam diameter is the size of Earth's diameter. And btw, they'll have to aim 4.3 years in advance, so (being nowhere near precise enough) 0.3 orbits ahead of wherever Earth is when they flip the switch. From the apparent magnitude wiki article, we'll just convert the m=0 flux for the "V"(= visible) band to m=+4 using Pogson's ratio, 2.512, raised to the (+4 - 0 =) 4th power: 2.512^4 = ~40. OK, so to have enough visible photon flux per unit area (we start with cm^2) for it to appear as an m+4 for everyone on Earth, we need 40 x 3.64E-20 (= ~1.5E-18) ergs/(s*cm^2*Hz). We need to get rid of the Hz. If we assume they're using a monochromatic beam smack dab in the middle of the visible light spectrum, say 550 nanometers (yellow) = lambda, and c = lambda*f (where c is the speed of light), so f = 3E8 (m/s)/5.5E-7 (m) = ~5E14 Hz. So 1.5E-18*5E14 = ~1E-3 ergs/(s*cm^2). 1 erg = 1E-7 Joule, so now we're at 1E-10 J/(s*cm^2) = 1E-10 W/cm^2. Sanity check before the final step: I guess this sounds kinda right. If cat toy laser pointers are around 1 mW (1E-3 W) and we're instructed to never shine them in peoples eyes (which are roughly a square centimeter), it makes sense that barely-discernible blinking lights in the sky should be around 10 million times less powerful. OK, best for last. Finally, we multiply by the cross-sectional area of the Earth... in square centimeters. Earth's radius is ~6000 km, = 6E8 cm, and pi*r^2 = ~1E18 cm^2. So those guys are rollin' with a 1E8 Watt laser. 100 million watts. Let's make it a "jiggawatt" (1E9 Watts) for funsies. According to gubbmint, you'd need about 400 windmills to power your laser. Only(?) 40 windmills for the 1E8 Watt laser. Problem is, you might want a lotta lasers. And the results for red and blue will be more or less similar, certainly well within an order of magnitude. If they built a truly dispersionless laser (not quite possible, but play along), and knew exactly where your eyeball would be at all times 4.3 years in the future, they could just use something as powerful as the toy laser, and it'd still damage your eye. Hey, what're you up to just after January 28th of 2024? Asking for a friend.... not only is it going to be a lot less work to take our atmosphere from 400ppm to 250, we're already here.
SETI & Drake Equation paragraph
Give me the energy requirements for a tightbeam visual signal from, say, Alpha Centauri B. I wanna be able to read morse code at night.
So, the final formula is: where: p - Pogson's ratio [] (dimensionless) m - magnitude [] (dimensionless) F - flux [J / (s * cm² * Hz)] c - speed of light [cm / s] λ - wavelength [cm] r - Earth's radius [cm] π - pi [] (dimensionless) Checking units: Power = [J / (s * cm² * Hz)] * [1 / s] * [cm²] Power = [J / (s * cm² * Hz)] * [Hz] * [cm²] Power = [J / s] * [(Hz * cm²) / (Hz * cm²)] Power = [J / s] = [W] No problems here. Using our values: p = 2.512 m = 4 F = 3.64E-27 [J / (cm² * Hz * s)] c = 3E10 [cm / s] λ = 5.5E-5 [cm] r = 6E8 [cm] pi = 3.14 we obtain: Power = 8.94E7 [W] So… pretty close and the difference comes down mainly to rounding. Other than that, under your assumptions, I see no problems with reasoning or method. Sorry for taking so long to respond, though. You need to double it, that's when Centaurs would get your message. Power = (p ^ m) * F * (c / λ) * π * r² Power = ([] ^ []) * [J / (s * cm² * Hz)] * [cm / s] * [1 / cm] * [] * [cm²] Power = (2.512 ^ 4) * 3.64E-27 * (3E10 / 5.5E-5) * 3.14 * (6E8)²Hey, what're you up to just after January 28th of 2024? Asking for a friend.
Thanks for the unicode formatting and generalization! I was in a hurry to get a quick response in. I'm happy to see we agree within about 10%, but if there's no calculus involved, is it even math at all?? :/
It's a good estimate of the lowermost power consumption, and you've done all the legwork. Kudos! Might be a base for fun Fermi problems or a reference point to some other interstellar communication discussions. Does it even need calculus? Beam dispersion would probably be some Gaussian bundle, dissipation is most likely adequately described as a sum of elements in form of whatnot_optical_coefficient * distance, error correction is a bunch of algebra, and involving any fancy astrophysics is just going to make us look desperate. Also, it's been a while since I had to use actual numbers to solve a problem. :Pbut if there's no calculus involved, is it even math at all?? :/
No no, I mean, when I do arithmetic or algebra only, it feels like I've cheated and made unrealistic assumptions. I'm almost inclined to go looking for an integral or something, but it's like you said, there's not a point, here. Maybe I am desperate! Us chump experimentalists use real numbers all the time. Come join us on the dark side, Devac :D. edit: But be careful out there! I've already written a satirical public service announcement skit that culminates with my pilot friend, wearing full captain's attire in the cockpit of the jets he flies, looking deadpan into the camera and saying, "Remember: If it's math, on a plane, it's a bomb."Does it even need calculus?
I just handed over my homework which concluded that the derivation of thermodynamic parameters in our model is A-OK because second derivatives are finite everywhere and third derivatives only tend to infinities when T = 0, which is, like, acceptable in critical systems under fluctuation/perturbation regime. We're all chumps, experimentalists just get swaggerific toys. Can't believe I forgot about that incident. Also, would love to see that PSA.when I do arithmetic or algebra only, it feels like I've cheated and made unrealistic assumptions.
Us chump experimentalists use real numbers all the time.
sigh NO, you say "damn, dude, are you seriously doing math for fun?" and then listen to what he says. The best conversations I've ever had have been interacting with people doing weird shit on planes. Last flight I saw someone writing up an inspection report on a '75 Targa and told him not to hate me because I drive a 996. I proceeded to have a 2-hour conversation with one of the world's foremost Porsche experts, a guy who gets paid by Larry Ellison to fly around buying Porsches for him, a guy who has bought and sold Porsches since he was sixteen years old, a guy who had so many stories about nameless rich people that I sat through four bourbons just goading him on. ALWAYS ask an expert about their expertise. You will learn shit you didn't even know you'd find interesting.
On the way back from Santa Fe, I sat next to a woman around my age, and I was working out some unit conversions in my notebook, pen and paper, just numbers and abbreviated units. She asks, "Looks like physics?", and I say, "Yeah! That's right, how'd you know?". And then she mentioned minoring in chemistry or something, but I forgot, because just a few exchanges later, we both went back to our own little worlds. Not even any awkwardness, just two people having some quality alone time on a plane. Which is about the most precious thing in the world after sharing a room to cut costs at a week-long conference.
Sorry Klein, bad joke about economics having basic logarithms and economic theory being a threat to national security. Of course I would at least ask. I've read enough of those papers to make me want to cry in my salad though. On the way back from Rwanda I actually met a dude who was pretty high up in the U.S. military. He served on peacekeeping missions in the Congo and stuff, and you bet he was opinionated on Trump. He knew a bunch of former colleagues that ended up promoted in the Department of State because they basically played the game. Shifted their plans in support of the new leader. It was an interesting perspective into how the inside of the government actually works and how the chain of command functions.
It's a much lower number than I expected, probably because in sci fi it's never a signalling laser, it's always a launch laser and that's a whole 'nuther animal. FUN FACT - disturbing portions of the historical record thinks Sirius was red. There are two real ways to resolve this: (1) presume that the historical record, as evidenced time and time again, is faulty (2) presume that the Sirians were pointing a launch/signalling laser at us for a few hundred years back in antiquity. (2) is a lot more fun and could be the impetus for a pretty fun sci fi conspiracy tale, or so I've heard. Or, if you're Larry Niven and Jerry Pournelle, you take the idea and throw it in the distant future at a completely different part of the galaxy so that your social commentary doesn't have to include people. 100MW is chump change. I've worked with powerplants that big. You can buy them on Alibaba. Which leads me to believe that divergence is more important than we're accounting for but I'm too lazy to do more than throw some numbers at an online calculator and watch it choke on the light years.
Do remember that we're discussing a case of illuminating Earth (and only Earth) with some dispersionless, cylinder-like, 100% efficient laser beam with perfect accuracy. Even then, with those idealisations, power scales with the square of the radius of the thing we want to illuminate. Accuracy is also fun: in our case, it's like pinpointing something roughly the size of a credit card on the surface of our Moon, but without the joys of 4.3 years worth of one-way delay or tracking a moving object. Also, I didn't say that divergence isn't significant. Just that it likely won't involve higher maths to find an approximation, which is semi-true. Had to do a double integral over a disk to get from intensity [W/m²] to power [W]. Here's how we can calculate the power delivered by a Gaussian beam, and it's ripe for plugging numbers in. I took the formulae and symbols from the article. There's also a calculation of how narrow the beam would have to be at its narrowest point, which turned out to be essentially zero (which I, perhaps mistakingly, interpreted as equivalent to a point source). Pinging am_Unition for peer review and help in moving it forward. It's not pretty, though. My initial intensity assumption goes asymptotically to infinity the narrower the beam, so there's possibly a problem/fuckup. I absolutely encourage everyone to play around with the numbers. Maybe it could work for other wavelengths?
Are you saying I just need 40 windmills to blind inhabitants of every close planet around? So now: How many windmill do I need to exterminate them? Asking for a friend After all, its a rational thing to do while I still have windmills and before they come with unknown intentions
That's the funniest sentence that I've read in a looooong time. But you're on a list now, ooli, you'll never be allowed into the Galactic Order. Bummer, dude. Correction: You'd need 40 windmills to get their attention by blinking out a message like a star turning on and off. OH, and I forgot to mention above, you'll need to position your laser a long, long way from the planet, because it's too close to the star for us to see anything but the star if it's anywhere near the planets. If "your friend" wanted to blind them, you'll need around, well, 400,000,000 windmills. How many do you have? How quickly does "your friend" need to exterminate said planet? "Your friend" could just cook them slowly with microwaves, and watch with enjoyment as their world grew hotter over several centuries (and you wouldn't even need to move far away from the star to do it). What I'm trying to say is that global warming is obviously not man-made, and we're gonna be in an alien stew. They'll time their arrival with when the meal's done. See now THIS is science.After all, its a rational thing to do while I still have windmills and before they come with unknown intentions
There is a 5 or so episode podcast series called “What is Life?” I recommend you check out. I will find a link and post it when I get home. It is geared toward folks like us who are interested in the sciences but are not scientists ourselves. Some of the answers that people give are quite entertaining and thought-provoking. I want to re-listen to it myself.