4 ms·

> aliens being here would imply FTL is possible Why? There are plenty of stars within a sub-light-speed radius since events that could've announced us to the g

> aliens being here would imply FTL is possible Why? There are plenty of stars within a sub-light-speed radius since events that could've announced us to the galaxy: advent of radio, first nuclear tests, etc.

lazide 5y ago
The sheer timescales and energy levels involved with all known methods of transportation is what makes it unlikely - at least for life on the timescales we live on. The odds someone is interested enough to spend truly mind boggling amounts of energy (literally moving hundreds of mountains worth) and hundred of years to check us out after one of those events - and not even say hi - is low. That they are also so close - also low. If they have some sort of magic drive tech (implied by the behavior of these drive sightings), then that changes the math a lot. Most people mean ‘magic drive tech’ when they say FTL.
- userulluipeste 5y ago
  "The odds someone is interested enough to spend truly mind boggling amounts of energy (literally moving hundreds of mountains worth) and hundred of years to check us out after one of those events - and not even say hi - is low. That they are also so close - also low." How could one even begin to make that kind of reasoning? Then the conclusion estimating the low probability is based on what? If I'd have to guess, I'd say otherwise - once a reasonably developed civilization (Kardashev type II and above) gets access to colossal amount of energy, there aren't that many things worth spending it (and attention in general) for. Life may or may not be plentiful around in the universe (it occured relatively shortly after Earth formation), but I'd bet sentient life is orders of magnitude more scarce, considering that it took billions for it to develop on Earth. That alone would make potential cradles for sentient life to be very interesting destinations to check once in a while. To provide here a relatable example, let's imagine a mostly desert continent, with a community living somewhere on its coast. At one point they develop enough capabilities to safely venture out in the desert and to make long journeys. How interested would they be in revisiting some oasis where they encountered some earthworms and small plants, and how interested would they be in revisiting a place (even across the continent, if that is what takes) with apes which happened to also exhibit some signs of primitive engineering? P.S.: With all that, I still hope we're alone within a large enough vicinity, so we won't have to deal with anyone else for as long as our species exists.
  - lazide 5y ago
    It’s pretty simple math? We’ve only had meaningful ‘not background event’ radio transmissions for about 115 years [https://en.m.wikipedia.org/wiki/Timeline_of_radio https://en.m.wikipedia.org/wiki/Timeline_of_radio]. Assuming no faster than light travel or similar magic (to the earlier point), but some near light speed magic drive, even if our potential visitors had the ability (and interest) to accelerate to light speed the moment they picked up Marconi’s initial broadcast, they would have to be within about 57-58 light years or less radius of us. There are roughly 1400 star systems within 50 light years of us [http://www.atlasoftheuniverse.com/50lys.html http://www.atlasoftheuniverse.com/50lys.html] Which sounds like a lot. But there is estimated to be about 10 to 100 billion star systems in the Milky Way alone. So the odds that any of those stars are occupied by any excitijg neighbors is pretty low, unless the number of alien species+occupied star systems is mind bogglingly large. If there are 100 occupied star systems randomly dispersed in the galaxy meeting all these requirements, it would be one in 70,000 to 1 in 700,000 odds for instance. Not great. And that is assuming a lot about how much energy they would be willing to expend. We’ve seen no evidence of anything resembling a Kardashev type civilization in the neighborhood. If there is magic FTL tech, obviously everything is different. Also, who knows maybe we grew up next door to an equivalent to a intergalactic bus depot. That would also change things. At least based on what we know now though, the tyranny of the rocket equation is rather complete, the distances involved in traveling between star systems so vast, and the energy requirements of even approaching C are so high that it is not a realistic thing to consider for life that works the way we do any time soon.
    - userulluipeste 5y ago
      Your math is sound, but I don't agree with all your data inputs. Specifically, that only (the engineered) radio signals would pick the attention of an alien civilization. (In fact, I think that Marconi's or most of the subsequent man generated signals, maybe with exception of nuclear detonations and such, were to faint to be picked up even from within the limits of our own planetary system.) The most obvious clue for presence of life, visible from far away, started with the Great Oxygenation Event. That enough should put Earth on anyone's map, and that happened 2 billions years ago. Achieving 100% of light speed is not possible within our current knowledge, but I assume that 20% should be for non life-carrier spacecraft, which at our galaxy's 200ly diameter gives us a cap of around 1'000 years of travel between most of the intra-galactic destinations. Even with a 10'000 technological head-start, a given civilization can devise a system to achieve galactic oversight. If there's indeed someone out there, with such a head-start, we should assume they're already watched our planet closely and maybe even getting a continuous track of our evolution. As for "we’ve seen no evidence of anything resembling a Kardashev type civilization in the neighborhood", although you're right, it's hardly useful to think in this frame. The available means that we had so far for observing anything in far away space were and still are pretty limited, for even inert phenomena. I'd say that counting on that to spot something sentient, where things are actively engineered, which may as well include engineering for the appearance itself, is overly optimistic.
flatline 5y ago
My favorite back of the napkin math about the practical reality of interstellar space travel, from cstross: https://www.antipope.org/charlie/blog-static/2007/06/the_high_frontier_redux.html https://www.antipope.org/charlie/blog-static/2007/06/the_hig...
knute 5y ago
Even near-lightspeed travel (say, >0.2C) would be leaps and bounds beyond what we know how to do at this point.

lazide 5y ago

The sheer timescales and energy levels involved with all known methods of transportation is what makes it unlikely - at least for life on the timescales we live on. The odds someone is interested enough to spend truly mind boggling amounts of energy (literally moving hundreds of mountains worth) and hundred of years to check us out after one of those events - and not even say hi - is low. That they are also so close - also low. If they have some sort of magic drive tech (implied by the behavior of these drive sightings), then that changes the math a lot. Most people mean ‘magic drive tech’ when they say FTL.

userulluipeste 5y ago
"The odds someone is interested enough to spend truly mind boggling amounts of energy (literally moving hundreds of mountains worth) and hundred of years to check us out after one of those events - and not even say hi - is low. That they are also so close - also low." How could one even begin to make that kind of reasoning? Then the conclusion estimating the low probability is based on what? If I'd have to guess, I'd say otherwise - once a reasonably developed civilization (Kardashev type II and above) gets access to colossal amount of energy, there aren't that many things worth spending it (and attention in general) for. Life may or may not be plentiful around in the universe (it occured relatively shortly after Earth formation), but I'd bet sentient life is orders of magnitude more scarce, considering that it took billions for it to develop on Earth. That alone would make potential cradles for sentient life to be very interesting destinations to check once in a while. To provide here a relatable example, let's imagine a mostly desert continent, with a community living somewhere on its coast. At one point they develop enough capabilities to safely venture out in the desert and to make long journeys. How interested would they be in revisiting some oasis where they encountered some earthworms and small plants, and how interested would they be in revisiting a place (even across the continent, if that is what takes) with apes which happened to also exhibit some signs of primitive engineering? P.S.: With all that, I still hope we're alone within a large enough vicinity, so we won't have to deal with anyone else for as long as our species exists.
- lazide 5y ago
  It’s pretty simple math? We’ve only had meaningful ‘not background event’ radio transmissions for about 115 years [https://en.m.wikipedia.org/wiki/Timeline_of_radio https://en.m.wikipedia.org/wiki/Timeline_of_radio]. Assuming no faster than light travel or similar magic (to the earlier point), but some near light speed magic drive, even if our potential visitors had the ability (and interest) to accelerate to light speed the moment they picked up Marconi’s initial broadcast, they would have to be within about 57-58 light years or less radius of us. There are roughly 1400 star systems within 50 light years of us [http://www.atlasoftheuniverse.com/50lys.html http://www.atlasoftheuniverse.com/50lys.html] Which sounds like a lot. But there is estimated to be about 10 to 100 billion star systems in the Milky Way alone. So the odds that any of those stars are occupied by any excitijg neighbors is pretty low, unless the number of alien species+occupied star systems is mind bogglingly large. If there are 100 occupied star systems randomly dispersed in the galaxy meeting all these requirements, it would be one in 70,000 to 1 in 700,000 odds for instance. Not great. And that is assuming a lot about how much energy they would be willing to expend. We’ve seen no evidence of anything resembling a Kardashev type civilization in the neighborhood. If there is magic FTL tech, obviously everything is different. Also, who knows maybe we grew up next door to an equivalent to a intergalactic bus depot. That would also change things. At least based on what we know now though, the tyranny of the rocket equation is rather complete, the distances involved in traveling between star systems so vast, and the energy requirements of even approaching C are so high that it is not a realistic thing to consider for life that works the way we do any time soon.
  - userulluipeste 5y ago
    Your math is sound, but I don't agree with all your data inputs. Specifically, that only (the engineered) radio signals would pick the attention of an alien civilization. (In fact, I think that Marconi's or most of the subsequent man generated signals, maybe with exception of nuclear detonations and such, were to faint to be picked up even from within the limits of our own planetary system.) The most obvious clue for presence of life, visible from far away, started with the Great Oxygenation Event. That enough should put Earth on anyone's map, and that happened 2 billions years ago. Achieving 100% of light speed is not possible within our current knowledge, but I assume that 20% should be for non life-carrier spacecraft, which at our galaxy's 200ly diameter gives us a cap of around 1'000 years of travel between most of the intra-galactic destinations. Even with a 10'000 technological head-start, a given civilization can devise a system to achieve galactic oversight. If there's indeed someone out there, with such a head-start, we should assume they're already watched our planet closely and maybe even getting a continuous track of our evolution. As for "we’ve seen no evidence of anything resembling a Kardashev type civilization in the neighborhood", although you're right, it's hardly useful to think in this frame. The available means that we had so far for observing anything in far away space were and still are pretty limited, for even inert phenomena. I'd say that counting on that to spot something sentient, where things are actively engineered, which may as well include engineering for the appearance itself, is overly optimistic.

flatline 5y ago

My favorite back of the napkin math about the practical reality of interstellar space travel, from cstross: https://www.antipope.org/charlie/blog-static/2007/06/the_high_frontier_redux.html https://www.antipope.org/charlie/blog-static/2007/06/the_hig...

knute 5y ago

Even near-lightspeed travel (say, >0.2C) would be leaps and bounds beyond what we know how to do at this point.