<p>If a planet is 1000 light years away, there is no way that we could be sure that there is life on it "now". However there is a probabilistic argument: Life takes many millions of years to develop, and the chance of a disaster being so great as to sterilise a planet is very small: case in point, the Earth hasn't been sterilised since the last common ancestor of all living things existed, nearly 4 billion years ago.</p>

<p>There is no way of knowing that life would continue to exist on a planet 1000 light years away during the many millennia that it would take for a probe to reach the distant planet. </p>

<p>Interstellar travel would take so long that we have to accept that no matter when we begin, we will not finish in our lifetime, and so we would do so for the benefit of our descendents. </p>

<p>Its not clear what you mean by "evolution is 10x faster" since evolution doesn't have a clearly defined speed.</p>

CC BY-SA 3.0
2016-05-25T19:17:26.970Z
2016-05-25T19:17:26.970Z
James K
<p>So, telescopes are like time machines. If we get an image and data for analysis from a planet say 1000 light years away, we are essentially looking 1000 years back in time. Now, if we notice presence of liquid water on it and somehow notice there is life on it, how do we know it still exists. There are so many possibilities.</p>

<p>It existed 1000 years back, then asteroid came and destroyed it. Or, the evolution on that planet was 10K times faster than what we have and life on that planet already existed to a better planet somewhere else.</p>

<p>Even if we send signals, we will have to wait for 2000 years to communicate assuming they send response instantaneously.</p>

<p>So, have the smarter beings on our planet already figured out a solution to this? I am sure they have thought of this problem already.</p>

CC BY-SA 3.0
2016-05-25T07:33:49.123Z
There isn't a solution, it IS impractical to communicate over interstellar distances.
James Screech
CC BY-SA 3.0
2016-05-25T07:34:33.053Z
Nope, the speed of light is a pretty fundamental barrier. The best you can do is to continuously transfer all information, and try to make forecasts for what happens next based on what you receive, corrected when you get new information.
SE - stop firing the good guys
CC BY-SA 3.0
2016-05-25T07:46:29.920Z
@JamesScreech is right, and that's basically the only answer to this question.  There is no known way.  Perhaps future discoveries will open a door to some creative way around that problem, or, perhaps not.  But based on what we currently know, there's no way around the 2,000 year wait.  Not even any good theories.   A few bad theories but no good ones.
userLTK
CC BY-SA 3.0
2016-05-25T09:32:48.570Z
@JamesScreech Then why bother getting to know it? How sad it will be find about some you *are* looking for but it is just way to far away.
danish
CC BY-SA 3.0
2016-05-25T10:03:51.880Z
Why bother? Because it's scientifically interesting to know about other places, even if there's no hope of travelling there. (I don't think this is something we can usefully debate on this site though.)
Andy
CC BY-SA 3.0
2016-05-25T10:10:13.817Z
@Andy I was hoping someone would mention that we will help to know origin of universe.
danish
CC BY-SA 3.0
2016-05-25T10:15:33.450Z
If the smarter beings on some other planet knew the answer to that question, I'd happily wait 2,000 years for an answer. But I don't think it's something we can debate here as it's off topic for the study of astronomy.
Andy
CC BY-SA 3.0
2016-05-25T11:05:00.557Z
"Smarter beings than us" is a nice assumption, but they still need to work within the laws of physics, as do we.  The laws of physics, at least based on what we know, make FTL communication very problematic and perhaps impossible.  Discussing that gets long and it's more theoretical science or pure physics than astronomy.  The short answer is still, it's not possible and there's no good argument that says it will be possible in the future.  For longer answers, see:  http://worldbuilding.stackexchange.com/questions/484/is-there-a-scientifically-plausible-faster-than-light-communication-system
userLTK
CC BY-SA 3.0
2016-05-25T11:06:45.160Z
Also, see http://physics.stackexchange.com/questions/78118/quantum-entanglement-as-practical-method-of-superluminal-communication and http://physics.stackexchange.com/questions/203831/ftl-communication-with-quantum-entanglement
userLTK
CC BY-SA 3.0
2016-05-25T20:16:19.200Z
What is your question? Figured out what? The speed of light? Yes. That it represents a fundamental barrier to the speed at which information can be passed? Yes.
adrianmcmenamin
CC BY-SA 3.0
2016-05-25T22:27:45.070Z
Recent experiments in quantum entanglement suggest a lower limit for the speed at which entanglement occurs between particles. That speed is 10,000 times the speed of light. If we learned how to communicate by quantum entanglement, maybe we'd be communicating with other races.
Howard Miller
<telescope><exoplanet>
Communicating with distant planet with life possibility
danish
# Communicating with distant planet with life possibility

(Asked by: username_0 on 2016-05-25)

So, telescopes are like time machines. If we get an image and data for analysis from a planet say 1000 light years away, we are essentially looking 1000 years back in time. Now, if we notice presence of liquid water on it and somehow notice there is life on it, how do we know it still exists. There are so many possibilities.

It existed 1000 years back, then asteroid came and destroyed it. Or, the evolution on that planet was 10K times faster than what we have and life on that planet already existed to a better planet somewhere else.

Even if we send signals, we will have to wait for 2000 years to communicate assuming they send response instantaneously.

So, have the smarter beings on our planet already figured out a solution to this? I am sure they have thought of this problem already.

**Tags:** telescope, exoplanet

> **Comments:**
> **username_1**: There isn't a solution, it IS impractical to communicate over interstellar distances.  
> **username_2**: Nope, the speed of light is a pretty fundamental barrier. The best you can do is to continuously transfer all information, and try to make forecasts for what happens next based on what you receive, corrected when you get new information.  
> **username_3**: @JamesScreech is right, and that's basically the only answer to this question.  There is no known way.  Perhaps future discoveries will open a door to some creative way around that problem, or, perhaps not.  But based on what we currently know, there's no way around the 2,000 year wait.  Not even any good theories.   A few bad theories but no good ones.  
> **username_0**: @JamesScreech Then why bother getting to know it? How sad it will be find about some you *are* looking for but it is just way to far away.  
> **username_4**: Why bother? Because it's scientifically interesting to know about other places, even if there's no hope of travelling there. (I don't think this is something we can usefully debate on this site though.)  
> **username_0**: @username_4 I was hoping someone would mention that we will help to know origin of universe.  
> **username_4**: If the smarter beings on some other planet knew the answer to that question, I'd happily wait 2,000 years for an answer. But I don't think it's something we can debate here as it's off topic for the study of astronomy.  
> **username_3**: "Smarter beings than us" is a nice assumption, but they still need to work within the laws of physics, as do we.  The laws of physics, at least based on what we know, make FTL communication very problematic and perhaps impossible.  Discussing that gets long and it's more theoretical science or pure physics than astronomy.  The short answer is still, it's not possible and there's no good argument that says it will be possible in the future.  For longer answers, see:  http://worldbuilding.stackexchange.com/questions/484/is-there-a-scientifically-plausible-faster-than-light-communication-system  
> **username_3**: Also, see http://physics.stackexchange.com/questions/78118/quantum-entanglement-as-practical-method-of-superluminal-communication and http://physics.stackexchange.com/questions/203831/ftl-communication-with-quantum-entanglement  
> **username_5**: What is your question? Figured out what? The speed of light? Yes. That it represents a fundamental barrier to the speed at which information can be passed? Yes.  
> **username_6**: Recent experiments in quantum entanglement suggest a lower limit for the speed at which entanglement occurs between particles. That speed is 10,000 times the speed of light. If we learned how to communicate by quantum entanglement, maybe we'd be communicating with other races.  

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## 1 answers

### Answer by username_7 on 2016-05-25. Score: 2

If a planet is 1000 light years away, there is no way that we could be sure that there is life on it "now". However there is a probabilistic argument: Life takes many millions of years to develop, and the chance of a disaster being so great as to sterilise a planet is very small: case in point, the Earth hasn't been sterilised since the last common ancestor of all living things existed, nearly 4 billion years ago.

There is no way of knowing that life would continue to exist on a planet 1000 light years away during the many millennia that it would take for a probe to reach the distant planet.

Interstellar travel would take so long that we have to accept that no matter when we begin, we will not finish in our lifetime, and so we would do so for the benefit of our descendents.

Its not clear what you mean by "evolution is 10x faster" since evolution doesn't have a clearly defined speed.


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