Could we communicate via radiowaves through interstellar space?

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bluestar

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Message 1861690 - Posted: 15 Apr 2017, 18:35:21 UTC - in response to Message 1861627.  
Last modified: 15 Apr 2017, 19:35:19 UTC

Chris.

The fact that Alpha Centauri is 4.4 light years away comes as a bit of a surprise to me.

I always thought of it as 4 light years.

Wikipedia makes it 4.37 light years, but your estimate at least beat my knowledge here.

Thanks for doing that and now I am off.
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Message 1861699 - Posted: 15 Apr 2017, 20:05:26 UTC
Last modified: 15 Apr 2017, 20:11:13 UTC

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Message 1861792 - Posted: 16 Apr 2017, 4:37:39 UTC - in response to Message 1861690.  

Bluestar, or whatever your name is this week. Isn't it rather obvious that I rounded the figure up to 1 significant figure? Not all of us have to deal in exact unnecessary details. Round it up again and it is indeed a nominal 4 light years away. Happy now?
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Message 1862242 - Posted: 18 Apr 2017, 18:48:18 UTC
Last modified: 18 Apr 2017, 18:49:17 UTC

La Repubblica paper says that Geoffrey Marcy and Nathaniel Tellis from Berkeley have analyzed data obtained by the Keck Telescope in Hawaii searching for laser signals possibly emitted by 5600 stars in our Galaxy and found none. The article has been published n the Astronomical Journal.
Tullio
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Message 1862327 - Posted: 19 Apr 2017, 11:28:54 UTC

Thanks for all your feedback so far! Personally, I think this is an interesting topic.

First of all, the main topic of this thread was the question of whether or not it would be technically possible to communicate over very large distances (between stars) via radio waves, because cosmic radiation might corrupt the message in a signal so much that it is unreadable by any recipient. This is purely theoretical (at the moment), since we have yet to find a communication partner.

@William Rothamel
Now: for high powered purposive "we are here" types of signals we would not expect them to be encrypted nor using any type of error correcting code.

I agree, if we only want to broadcast the fact that we exist, then we do not need any type of error correcting code. This is because there is no information we want to transmit and we simply hope that other intelligent species can detect the difference between "natural" and "man-made" signals. And the steps you discribed that we should follow in case we detect something seem like a good solution. But as I stated in my previous response, if the signal gets corrupted or changed by cosmic radiation too much the language or number representation will be jibberish even after you "clean" it up. Although I don't know how bad this corruption is, which is why I opened this thread.

@bluestar
I read your long response even though I had a hard time trying to understand your point. Whether or not the big bang was caused by a "god" or "creator" is not really relevant in this discussion. No matter how the universe got its fundamental constants and physical laws, we are unable to change them and therefore need to use what we have. Of course it is hypothetical if there is other life in the universe, but for the sake of argument we accept the possibility. I'm more interested in how we could effectively communicate with other intelligent life forms via the current technology that we have, and by that I mean via radio waves.

@rob smith
Communication implies that the two ends of the link "talk" to each other. This is irrespective of what the modulation and encoding of the message.

Communication implies that both sender and recipient have agreed upon an encoding. The symbols we use in the english language is also an encoding. That means that we both are currently communicating using the agreed upon code (the english language). If you started to answer in japanese, I would not be able to interpret the information no matter how fast or how good the quality of the message is, therefore we would technically not be communicating. Computers depend on this even more, if you just send streams of bits (101010001) there is no way for the recipient computer to figure out what you were trying to send. A broadcast is still a form of communication, the opposite you may be referring to is a unicast (only between two parties). As stated above, I am curious about the plausibility of a direct communication (unicast) with another species, which includes an agreed upon encoding for the information itself and also the error correction that encompasses the message for a safe transmission. It may take a long time, but that does not mean that it is not possible. For example, you could theoretically slow down the TCP connection-oriented network protocol, and it would still be considered unicast communication.

Of course communicating with other lifeform is only possible after we have actually found one. This includes finding "unnatural" signals and identifying them as from other intelligent beings. My question was more about what we do AFTER we have found others (that may also have noticed us) and about how we could communicate with them and if this is actually technically possible with all the distrubance by radiation. Does anyone of you know how much cosmic radiation influences / corrupts / alters / changes radio waves? Does it only affect it a little bit (f.e. max 25%) or does it completely corrupt anything we try to send outside our solar system?
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Message 1862461 - Posted: 20 Apr 2017, 7:40:12 UTC

My thoughts on transmitting a radio signal to the stars would suggest an on/off radio or laser signal, repeatedly sending out a short approximation of the value of PI. Mathematics can be the only common language initially.
Either with varying length pulses corresponding to the value of the digits ( ______ _ __ _________ __ ____________ )
OR
groups of short equal length pulses with each group containing the number of pulses corresponding to the digits value ( ||| | |||| | |||||| ).
Name change to reflect my BOINC ID number
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Message 1862465 - Posted: 20 Apr 2017, 9:33:48 UTC - in response to Message 1862461.  

The value of Pi is constant throughout the universe, that is a fundamental given. Just imagine a confrontation between a human and an ET, neither of which speak the others language. The human puts a stick in the ground, ties a rope to it, and draws a circle around the stick. He then takes another bit of rope, the length of the diameter and lays it around the perimeter. He holds up 1 finger. He does it 2 more times holding up two fingers and then 3 fingers. Then a little bit extra for the final bit.

He then writes down 3.142 or 3 times and a bit. Any intelligent being would understand the ratio being referred to, and immediately you have dialogue.
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Message 1862497 - Posted: 20 Apr 2017, 14:48:24 UTC - in response to Message 1862327.  
Last modified: 20 Apr 2017, 14:49:46 UTC

If I'm not mistaken, there is no single answer to how much effect radio noise from the cosmos would have on a complex signal. There are many important variables to consider. Among these:

1.) The power of the signal

2.) The gain of both the sending and the receiving antennas

3.) The frequency of the signal, some being noisier than other.

4.) The bandwidth of the signal, both in itself, and in relation to the bandwidth of the receiver channel.

5.) The modulation method used in the signal
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Message 1862521 - Posted: 20 Apr 2017, 17:14:36 UTC

...and all of the above pale into insignificance when we take into account the time it takes for a radio signal to get from stellar system A to stellar system B.
Take for example a message to a ship heading from Earth to Alpha Centauri, a mere 4.5 light years away. Using a fairly simple ion drive system this vessel is expected to take about 40 years to get there, accelerating for about half the distance, then decelerating for the rest. About half way into the mission a call goes out from earth, it gets the the ship two years later - the message is "Come back, Great Aunt Maude is seriously ill". A two weeks later Great Aunt Maude dies, a second message is sent, and arrives two years and two weeks later. In the mean time her great nephew has responded "Will she hang on for another few years?", then a couple of weeks later with "Sorry I missed the funeral, I'll be back as soon as I can...".
Is that communication?
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Message 1862535 - Posted: 20 Apr 2017, 19:13:30 UTC

A good example that assumes that communications travel at the speed of light even if the ships don't. even the we are talking 4 years for a message and it's reply. If Einstein can't be proved wrong we are stuffed!!
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Message 1862543 - Posted: 20 Apr 2017, 20:39:53 UTC

If they can get a space warp to work, like the one Dr. White's working on at NASA, but on a much larger scale, we could have faster than light communication and travel. Doesn't even contradict relativity theory, as this deals with local velocity-- distance over time, from point A to point B, not virtual or global velocity, as when space itself is moved, or warped, rather than a vessel or a message.
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Message 1862549 - Posted: 20 Apr 2017, 21:04:53 UTC

...then we wouldn't be using "traditional" radio communications, but something very different.
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Message 1862551 - Posted: 20 Apr 2017, 21:33:28 UTC - in response to Message 1862543.  
Last modified: 20 Apr 2017, 21:39:58 UTC

If they can get a space warp to work, like the one Dr. White's working on at NASA, but on a much larger scale, we could have faster than light communication and travel. Doesn't even contradict relativity theory, as this deals with local velocity-- distance over time, from point A to point B, not virtual or global velocity, as when space itself is moved, or warped, rather than a vessel or a message.

"If they can get a space warp to work".
Yes it possible.
But do you know how much energy that requires?
It takes a LOT of mass or energy to warp spacetime!
Both matter and information are stuck to the speed limit that is the speed of light.
That means communication via radiovawes are also limited to the speed of light.
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Message 1862558 - Posted: 20 Apr 2017, 22:33:59 UTC - in response to Message 1862551.  

Dr. White, at NASA, has been working with a very modest level of electrical power, and has seen some encouraging, if tentative, results, suggesting the formation of a small space warp. With somewhat increased power and added efficiencies, this might be practical one day, contrary to the predictions that an impossibly large amount of energy would be required to warp space.
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Message 1862559 - Posted: 20 Apr 2017, 22:38:31 UTC - in response to Message 1862549.  

...then we wouldn't be using "traditional" radio communications, but something very different.


It's difficult to guess exactly how space warp communications might be accomplished. If nothing else, a automated messenger drone might be space-warped to a distant location, and then deliver its recorded message by radio.
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Message 1862564 - Posted: 20 Apr 2017, 23:10:59 UTC - in response to Message 1862558.  

Dr. White, at NASA, has been working with a very modest level of electrical power, and has seen some encouraging, if tentative, results, suggesting the formation of a small space warp. With somewhat increased power and added efficiencies, this might be practical one day, contrary to the predictions that an impossibly large amount of energy would be required to warp space.

What is a small space warp?
When travelling you need large space warps.
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Message 1862567 - Posted: 20 Apr 2017, 23:44:17 UTC - in response to Message 1862564.  
Last modified: 20 Apr 2017, 23:46:19 UTC

As the saying goes-- you have to crawl before you can walk! If the experimental results can be confirmed, it would presumably be possible to go to a larger scale, using what was learned from the small version.
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Message 1862619 - Posted: 21 Apr 2017, 4:27:12 UTC - in response to Message 1862567.  

As the saying goes-- you have to crawl before you can walk! If the experimental results can be confirmed, it would presumably be possible to go to a larger scale, using what was learned from the small version.

That's true:)
https://en.wikipedia.org/wiki/White%E2%80%93Juday_warp-field_interferometer
But for some reason I get the feeling that the experiment shows some quantum effects still unknown to science.
Upscaling quantum effects seems impossible to me.
But if one succeed to warp space around photons...
By all means.
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Message 1862675 - Posted: 21 Apr 2017, 10:20:47 UTC - in response to Message 1862619.  

Mass warps space
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Message 1862677 - Posted: 21 Apr 2017, 10:45:24 UTC - in response to Message 1862675.  
Last modified: 21 Apr 2017, 10:51:21 UTC

Mass warps space

Of course.
So does negative mass.
But it requires a LOT of mass to even notice the warped space.
Objects like our Sun does it.
https://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury
In order to get gravitational lensing effects you need at least the mass like in a galaxy.
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