9 ms·

Distance is 120 light years. So whatever we see is 120 years in the past. Getting there within a reasonable time frame is impossible with our current technology

by Gys 3y ago

Distance is 120 light years. So whatever we see is 120 years in the past. Getting there within a reasonable time frame is impossible with our current technology (an unmanned rocket will still needs 1000s of years). The good news: if there is intelligent life it will not easily get here either.

King-Aaron 3y ago
> The good news: if there is intelligent life it will not easily get here either. Unless 'it' left a long time ago and is already here. I always feel the 'space is big haha no one can cross it' argument is weird due to always framing it in our own frame of reference. What if the hypothetical 'thing' is like a jellyfish and time isn't as big an issue, or an AI that definitely doesn't care about time. Or a bundle of fungus that doesn't necessarily care one way or another.
- konschubert 3y ago
  If you have enough acceleration , you can travel 1000 light years in a human lifetime. It’s just that when you return, at least 2000 years will have passed on earth.
  - pomtato 3y ago
    so you're implying speed atleast 10x the speed of light? i think you'll have better luck increasing the human lifespan instead.
    - rowanG077 3y ago
      Not that's not what he is implying. He is talking about time dilation.
      - melvinmelih 3y ago
        How does one travel 1000 light years in a span of human lifetime (~80 yrs) if you’re not going faster than the speed of light?
        kawzeg 3y ago
        Time dilation! Time is relative. For an outside observer, over 1000 years pass, but aboard the ship, much less time passes. There are calculators for this, e.g. at [0]. If you constantly accelerate at 1g, flip around at the halfway point and accelerate in the opposite direction for the rest of the journey, roughly 13 years would pass from the traveler's perspective. This site also has a "Newton's universe" mode, which pretends that relativity doesn't exist. Interestingly, in that case you would take over 44 years! [0]: https://www.omnicalculator.com/physics/space-travel?c=EUR&v=acceleration:1!g,planet_star:0,mode:1,world:0,efficiency1:100!perc!l,efficiency2:100!perc!l,efficiency3:100!perc!l,efficiency4:100!perc!l,ship_mass:200!t,distance:1000!ly https://www.omnicalculator.com/physics/space-travel?c=EUR&v=...
        konschubert 3y ago
        I am pretty rusty in special relativity, but IIRC, in the ship it basically seems like the distance is contracting as you accelerate. And from earth, it seems like time is going slower inside the moving spaceship.
        Anarch157a 3y ago
        With relativistic time dilation. 1000 years will pass on Earth, but on tge ship, it will be only a couple of decades, assuming they're close enough to the speed of light.
    - CalRobert 3y ago
      """ Time dilation is the difference in elapsed time as measured by two clocks, either due to a relative velocity between them (special relativity) or due to a difference in gravitational potential between their locations (general relativity). When unspecified, "time dilation" usually refers to the effect due to velocity. """ https://en.wikipedia.org/wiki/Time_dilation https://en.wikipedia.org/wiki/Time_dilation
      - pomtato 3y ago
        wow thanks! this was super fun, do you happen to have some souce about the calculations that go into determining the time dilation based on different velocity? i'm aware about black holes being capable of well, doing time dilation thingy due to their massive gravitational force but nothing else. edit: souce as in something a regular average joe can make sense of haha
        CalRobert 3y ago
        Well, depending on your preferred format there's a great book called A Brief History of Time - https://en.wikipedia.org/wiki/A_Brief_History_of_Time https://en.wikipedia.org/wiki/A_Brief_History_of_Time , or lots of videos about it at https://www.youtube.com/results?search_query=time+dilation https://www.youtube.com/results?search_query=time+dilation More broadly, the series Cosmos with Carl Sagan was excellent, and is worth a view. The bit about time dilation is at https://www.youtube.com/watch?v=kWgEzxi_A0w https://www.youtube.com/watch?v=kWgEzxi_A0w . The more recent one with Neil Degrasse Tyson is also good (but while I enjoy both, I think I prefer the older one)
        hermitcrab 3y ago
        The time dilation equation from special relativity only needs basic maths: https://www.omnicalculator.com/physics/time-dilation https://www.omnicalculator.com/physics/time-dilation
  - adhoc32 3y ago
    1g constant acceleration is enough. But we don't have the technology yet.
- perihelions 3y ago
  Even simpler: you send out self-replicating AI drones in advance—to every star in the entire galaxy. That guarantees permanent security. The drones assess if alien intelligences have any potential to become a threat, and if so annihilates their planet, by autonomous decision. Takes a few million years to set up... but that's just a blink of an eye on cosmic time scales; a brief era in the galactic-scale lifespan of an advanced civilization. (The civilizations that don't do something like this don't live that long).
  - sgt 3y ago
    But those evolve later and come back to you, biting you in the ass.
    - gsky 3y ago
      That's something we are very good at
  - ajuc 3y ago
    This is one of these things that sound easy as long as you don't think about the details :) Annihilating planets takes a lot of energy. For example if our Sun goes supernova it will maybe kill all life on Earth, but the planet will still exist. If you gather enough energy to potentially annihilate a planet in each star system in a galaxy - you won't need to worry about any civillization becoming a threat in the first place, because they won't have any energy left to become that threat :) Then there're the problems with relying on autonomus system with such energy at its disposal, and the problems with dealing with genetic/cultural drift. What if your species diverges into several ones that start fighting each other - which one is the one that's supposed to be protected from the other? What if different parts of this system disagree? Who gets to push updates to the code of this system? How do you supervise this? Imagine a military coup or constutitional crisis and you're the guy that keeps the ssh key :) Are distant colonies that get independence and develop on their own a threat? Would the regions that want autonomy agree to this? Or if this technology exist - wouldn't it be used for wars inside that species long before they can start to worry about the so-far-uninhabited rest of the Galaxy? Would they even survive long enough to create this? Imagine Sumerians created such system on Earth and it wakes up after 5000 years and asks us for password in some dead language or else :) Now change that to 1 000 000 years. In my opinion it's very unlikely something like this ever gets created simply because of all the coordination and trust issues, the energy and technology dependencies, the probability and severity of problems it can cause vs the problems it can solve. Wasting significant percentage of energy of the galaxy and risking destroying it accidentally just to save yourself some diplomacy sounds like the ultimate tech solution to people problem :) And you're not really avoiding the diplomacy, you're just doing it upfront - internally. I'd be very surprised if there were no wars caused by someone trying to implement such idea. Imagine writing a proposal to Congress or EU to start doing this :) And how Chinese and Russian would react.
- kypro 3y ago
  The thing I always found a bit unnerving is that if they've left and are traveling at a speed close to the speed of light we'd never know until they arrive. If something is traveling at the speed of light towards us (whether a ship or a death star laser) we wouldn't know until it arrived. Now we've been sending radio signals for several decades you have to begin to question if there's a civilisation out there maybe 10-100 light years away that may now be aware of us and have sent something our way which may be about to arrive. There is an explanation for Fermi paradox that suggests maybe alien civilisations choose to be quiet or immediately wipe out other transmitting civilisations with speed of light weaponry. Why? Well, if there's no way to have prior warning of an attack traveling at the speed of light your only defence is some combination of remaining hidden and extreme hostility towards other civilisations.
  - postexitus 3y ago
    Welcome to The Dark Forest.
  - raverbashing 3y ago
    Most likely explanation? You can't travel at close (even 1%) of the speed of light without dealing with interstellar gas compression, object collision, passing through any moderately strong magnetic field without deviating, etc
    - londons_explore 3y ago
      I suspect future people will solve these problems.
- hermitcrab 3y ago
  Slow, long-duration mission have their own issues. Even a jellyfish or fungus has to eat. Carrying enough food for a multi-thousand year mission is a problem. And an AI needs power, which might be hard to come by between the stars.
- checkyoursudo 3y ago
  > Unless 'it' left a long time ago and is already here. Might be posting on HN right now. Never know. All your hypotheticals are not entirely unreasonable, but they are also so far beyond our current ability to test, that it becomes pretty futile to speculate, except as a source of entertainment. Space is reaaaaaaaaaaaaaally big, much bigger than people really have a conception of. Bigger than I have a conception of, and I try really hard to understand how bad my conception of it is. A space fungus from 120 light years away would presumably only reach us by almost 100% chance, which is something I am comfortable saying is almost 100% unlikely. This is true of most hypothetical threats. Fantasies about aliens or AI coming here (or sending big rocks) to exterminate are as weird to me, as I image "space is big haha" is to you. There is no reason for anyone even to try to cross interstellar distances, especially not for war. The expected gain will never be worth the cost, outside of some fantasy FTL-for-free engine, which is just that: fantasy. But, it is fun to think about it all.
dncornholio 3y ago
120 light years is nothing. Light is pretty slow seen from the cosmic scale.
_joel 3y ago
> if there is intelligent life it will not easily get here either. We made need to redefine intelligent life if we think of ourselves as the pinacle of intelligence or rather in the upper eschelons.
deafpolygon 3y ago
And if you think about it... 100-200 years of progress can be pretty significant. Just look at human civilization.

by Gys 3y ago

King-Aaron 3y ago

> The good news: if there is intelligent life it will not easily get here either. Unless 'it' left a long time ago and is already here. I always feel the 'space is big haha no one can cross it' argument is weird due to always framing it in our own frame of reference. What if the hypothetical 'thing' is like a jellyfish and time isn't as big an issue, or an AI that definitely doesn't care about time. Or a bundle of fungus that doesn't necessarily care one way or another.

konschubert 3y ago
If you have enough acceleration , you can travel 1000 light years in a human lifetime. It’s just that when you return, at least 2000 years will have passed on earth.
- pomtato 3y ago
  so you're implying speed atleast 10x the speed of light? i think you'll have better luck increasing the human lifespan instead.
  - rowanG077 3y ago
    Not that's not what he is implying. He is talking about time dilation.
    - melvinmelih 3y ago
      How does one travel 1000 light years in a span of human lifetime (~80 yrs) if you’re not going faster than the speed of light?
      - kawzeg 3y ago
        Time dilation! Time is relative. For an outside observer, over 1000 years pass, but aboard the ship, much less time passes. There are calculators for this, e.g. at [0]. If you constantly accelerate at 1g, flip around at the halfway point and accelerate in the opposite direction for the rest of the journey, roughly 13 years would pass from the traveler's perspective. This site also has a "Newton's universe" mode, which pretends that relativity doesn't exist. Interestingly, in that case you would take over 44 years! [0]: https://www.omnicalculator.com/physics/space-travel?c=EUR&v=acceleration:1!g,planet_star:0,mode:1,world:0,efficiency1:100!perc!l,efficiency2:100!perc!l,efficiency3:100!perc!l,efficiency4:100!perc!l,ship_mass:200!t,distance:1000!ly https://www.omnicalculator.com/physics/space-travel?c=EUR&v=...
        konschubert 3y ago
        I am pretty rusty in special relativity, but IIRC, in the ship it basically seems like the distance is contracting as you accelerate. And from earth, it seems like time is going slower inside the moving spaceship.
      - Anarch157a 3y ago
        With relativistic time dilation. 1000 years will pass on Earth, but on tge ship, it will be only a couple of decades, assuming they're close enough to the speed of light.
  - CalRobert 3y ago
    """ Time dilation is the difference in elapsed time as measured by two clocks, either due to a relative velocity between them (special relativity) or due to a difference in gravitational potential between their locations (general relativity). When unspecified, "time dilation" usually refers to the effect due to velocity. """ https://en.wikipedia.org/wiki/Time_dilation https://en.wikipedia.org/wiki/Time_dilation
    - pomtato 3y ago
      wow thanks! this was super fun, do you happen to have some souce about the calculations that go into determining the time dilation based on different velocity? i'm aware about black holes being capable of well, doing time dilation thingy due to their massive gravitational force but nothing else. edit: souce as in something a regular average joe can make sense of haha
      - CalRobert 3y ago
        Well, depending on your preferred format there's a great book called A Brief History of Time - https://en.wikipedia.org/wiki/A_Brief_History_of_Time https://en.wikipedia.org/wiki/A_Brief_History_of_Time , or lots of videos about it at https://www.youtube.com/results?search_query=time+dilation https://www.youtube.com/results?search_query=time+dilation More broadly, the series Cosmos with Carl Sagan was excellent, and is worth a view. The bit about time dilation is at https://www.youtube.com/watch?v=kWgEzxi_A0w https://www.youtube.com/watch?v=kWgEzxi_A0w . The more recent one with Neil Degrasse Tyson is also good (but while I enjoy both, I think I prefer the older one)
      - hermitcrab 3y ago
        The time dilation equation from special relativity only needs basic maths: https://www.omnicalculator.com/physics/time-dilation https://www.omnicalculator.com/physics/time-dilation
- adhoc32 3y ago
  1g constant acceleration is enough. But we don't have the technology yet.
perihelions 3y ago
Even simpler: you send out self-replicating AI drones in advance—to every star in the entire galaxy. That guarantees permanent security. The drones assess if alien intelligences have any potential to become a threat, and if so annihilates their planet, by autonomous decision. Takes a few million years to set up... but that's just a blink of an eye on cosmic time scales; a brief era in the galactic-scale lifespan of an advanced civilization. (The civilizations that don't do something like this don't live that long).
- sgt 3y ago
  But those evolve later and come back to you, biting you in the ass.
  - gsky 3y ago
    That's something we are very good at
- ajuc 3y ago
  This is one of these things that sound easy as long as you don't think about the details :) Annihilating planets takes a lot of energy. For example if our Sun goes supernova it will maybe kill all life on Earth, but the planet will still exist. If you gather enough energy to potentially annihilate a planet in each star system in a galaxy - you won't need to worry about any civillization becoming a threat in the first place, because they won't have any energy left to become that threat :) Then there're the problems with relying on autonomus system with such energy at its disposal, and the problems with dealing with genetic/cultural drift. What if your species diverges into several ones that start fighting each other - which one is the one that's supposed to be protected from the other? What if different parts of this system disagree? Who gets to push updates to the code of this system? How do you supervise this? Imagine a military coup or constutitional crisis and you're the guy that keeps the ssh key :) Are distant colonies that get independence and develop on their own a threat? Would the regions that want autonomy agree to this? Or if this technology exist - wouldn't it be used for wars inside that species long before they can start to worry about the so-far-uninhabited rest of the Galaxy? Would they even survive long enough to create this? Imagine Sumerians created such system on Earth and it wakes up after 5000 years and asks us for password in some dead language or else :) Now change that to 1 000 000 years. In my opinion it's very unlikely something like this ever gets created simply because of all the coordination and trust issues, the energy and technology dependencies, the probability and severity of problems it can cause vs the problems it can solve. Wasting significant percentage of energy of the galaxy and risking destroying it accidentally just to save yourself some diplomacy sounds like the ultimate tech solution to people problem :) And you're not really avoiding the diplomacy, you're just doing it upfront - internally. I'd be very surprised if there were no wars caused by someone trying to implement such idea. Imagine writing a proposal to Congress or EU to start doing this :) And how Chinese and Russian would react.
kypro 3y ago
The thing I always found a bit unnerving is that if they've left and are traveling at a speed close to the speed of light we'd never know until they arrive. If something is traveling at the speed of light towards us (whether a ship or a death star laser) we wouldn't know until it arrived. Now we've been sending radio signals for several decades you have to begin to question if there's a civilisation out there maybe 10-100 light years away that may now be aware of us and have sent something our way which may be about to arrive. There is an explanation for Fermi paradox that suggests maybe alien civilisations choose to be quiet or immediately wipe out other transmitting civilisations with speed of light weaponry. Why? Well, if there's no way to have prior warning of an attack traveling at the speed of light your only defence is some combination of remaining hidden and extreme hostility towards other civilisations.
- postexitus 3y ago
  Welcome to The Dark Forest.
- raverbashing 3y ago
  Most likely explanation? You can't travel at close (even 1%) of the speed of light without dealing with interstellar gas compression, object collision, passing through any moderately strong magnetic field without deviating, etc
  - londons_explore 3y ago
    I suspect future people will solve these problems.
hermitcrab 3y ago
Slow, long-duration mission have their own issues. Even a jellyfish or fungus has to eat. Carrying enough food for a multi-thousand year mission is a problem. And an AI needs power, which might be hard to come by between the stars.
checkyoursudo 3y ago
> Unless 'it' left a long time ago and is already here. Might be posting on HN right now. Never know. All your hypotheticals are not entirely unreasonable, but they are also so far beyond our current ability to test, that it becomes pretty futile to speculate, except as a source of entertainment. Space is reaaaaaaaaaaaaaally big, much bigger than people really have a conception of. Bigger than I have a conception of, and I try really hard to understand how bad my conception of it is. A space fungus from 120 light years away would presumably only reach us by almost 100% chance, which is something I am comfortable saying is almost 100% unlikely. This is true of most hypothetical threats. Fantasies about aliens or AI coming here (or sending big rocks) to exterminate are as weird to me, as I image "space is big haha" is to you. There is no reason for anyone even to try to cross interstellar distances, especially not for war. The expected gain will never be worth the cost, outside of some fantasy FTL-for-free engine, which is just that: fantasy. But, it is fun to think about it all.

dncornholio 3y ago

120 light years is nothing. Light is pretty slow seen from the cosmic scale.

_joel 3y ago

> if there is intelligent life it will not easily get here either. We made need to redefine intelligent life if we think of ourselves as the pinacle of intelligence or rather in the upper eschelons.

deafpolygon 3y ago

And if you think about it... 100-200 years of progress can be pretty significant. Just look at human civilization.