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How to send a message to ET

  1. Mar 20, 2009 #1
    Hello all,

    I'm doing some research as to how a message should be sent to an ET. I know a radio signal was sent out from earth, I belive in the 60s or 70s, but nothing recent. Does anybody know of a group doing something along this line?

  2. jcsd
  3. Apr 10, 2009 #2
    That would have been in 1974. A message sent from Arecibo beamed to M13, the Hercules globular cluster. Something in the order of 25k light years away.

    I don't think there has been any 'organized' attempt since then or anything at the present time

    However, because of the activity here, if one were to look in this direction from lights years out. Optically there would not be much, but in the radio spectrum it would be quite bright.

    Most of the radio telescope activity is geared to listening rather than transmitting.
  4. Apr 10, 2009 #3
    Well technically since we've invented radio, we've been transmitting every since.
  5. Apr 11, 2009 #4


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    The speed of light is a very real barrier. We accidently sent signals out about 100 years ago. Assuming aliens are listening, weve only reached out about 50 light years. The message we sent to the globular cluster 25k light years away - priceless.
  6. Apr 11, 2009 #5
    Interesting point Chronos.

    I was giving a lecture (actually much more like a talk) the a grade six class last week on astronomy.
    The subject got around to exoplanets and the possibility of intelligent life.

    One of the kids asked me, "how do they send signals out into space".
    I caught myself before I went off on a tangent. I smiled and said, "you all send message into space".
    The mouths opened and you could have heard a pin drop.

    I told them every time you text a message, use a cell phone, and most other forms of electromagnetic communication end up partially going into space.

    They thought that was quite cool.

    It was a grade six class so I did not get into inverse square and such.

    Anyway back on the subject, when one looks at the technology change over the past decades. With the advent of more cable, fiber optics, narrow beam satellites and such, our radio signature must be diminishing.

    I would venture to guess in ≈40 years or so, provided we don't inilate ourselves, our radio spectrum signature may be quite small.

    If we broadcast our presence, we may have to do it intentionally rather than accidentally.

    How ironic......
  7. Apr 11, 2009 #6


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    Exactly. Although, this doesn't give much hope to SETI if the radio-lifetime of a civilization is only ~150 years...
  8. Apr 11, 2009 #7

    I think SETI already realizes an ET is not likely to be sending a signal and has set its sites on listening for deep space radar. But if ET wanted to be heard intentionally with radio then it would be a good idea to broadcast across a very broad spectrum a binary signal that encoded the main carrier frequency where the actual message is on. So ET, if it really wanted to be heard, would send short pulses, a micro-second, indicating where to tune in for the main message across thousands, maybe millions of bands.

    On anohter note: I never thought the content of a message was ever taken seriously enough by sci-fi writers and scientist. A good message would tailor the signal to a very broad spectrum of listeners. Of course starting off with simple binary arithmetic but then progress to a computer machine code. After that the message is a download of an OS with tons of software. The beauty to this approach is that it doesn't require the listener to invent anything. If the listener can just pick up radio then they get the binary arithmetic and know it's from an ET. IF they do know how to make computers then they can make a machine that can run the machine code or get one of their off the shelf machines to emulate the ET code!

    Anyone up for a Linux ET message? If the OS and software bundle are compressed and of course use a 32 bit version you may get away with a few gigabytes of data. The next question is how many stars do you want to hit? If the answer is millions then you need allot of transmitters and the bandwidth has to be very high to send all that data fast enough to target all those stars. If the answer is a few thousand then bandwidth constraints and hardware could be within a budget of a 20 million dollars or less for the setup and perhaps just under 100 thousand/per year to maintain the transmission?

    What should be included in the software bundle, besides instructions? Too bad the virtual telescope and tons of off the shelf educational software only works under MS Windows. I hope Bill Gates doesn't get this idea and fund an ET message using Windows... Of course if he did ET may send the message back and fix all the bugs in Vista!

  9. Apr 11, 2009 #8


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    If we no longer transmit in the radio frequencies, why should we still prepare to receive them? Once the radio technology is completely superseded, neither transmitters nor receivers will be readily available, certainly not constantly operating.

    Therefore, you have to have a civilization that is purposely transmitting a signal and a civilization that is purposefully listening for the signal.
  10. Apr 11, 2009 #9
    I can't think of one situation where radio would not be used to communicate to spacecraft, Laser is an obvious alternative but it would have problems with cloud cover, unless of course you think entanglement could be used to communicate remotely? Most, if not all physists don't think entangelment could be used to send information. Terrestrial radio communication obviously can be replaced with cable, fibers, etc.

    The use of deep space radar for planetary transportion could be replaced with a SPS (Solar Positioning System) smiliar to GPS, but used for solar system planetary navigation, but this would require radio as well.

  11. Apr 11, 2009 #10


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    That's a good point I neglected communications with anything in outer-space. You're probably right, and I can't think of a viable alternative to radio communication either. I stand corrected!
  12. Apr 12, 2009 #11


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    Subspace radio, anyone? The speed of light is a serious issue. Communicating with a civilization even as near as 50 light years is problematic. Takes 100 years before you get a reply.
  13. Apr 12, 2009 #12

    You can imagine two machine civilizations communicating with each other by uploading some of their software to each other via radio. So, they simply visit each other and then they can talk without any delay. After the meeting they leave. Visiting and leaving takes some time, but talking doesn't. Also, the ETs that are uploading themselves don't notice the travel time.
  14. Apr 12, 2009 #13


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    The cold truth of relativity :frown:
  15. Apr 12, 2009 #14
    The future of human interstellar space travel! We encode our conciousness in the signal and if the listener can build sophisticated enough CPUs then they get real time contact with ET.

    At least this way we can travel at c to where ever we want to travel in the universe...

    The real joke, IMHO, is human space travel will be with big O spaceships like the Enterprise of Star Trek.

    Last edited: Apr 12, 2009
  16. Apr 12, 2009 #15


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    You know what always bugs me about that? There will be two ships in the middle of nowhere and somehow they manage to see each other (visual). The nearest stars are parsecs away and yet the ships glow as if they were freakin' stars. Makes absolutely no sense, lol.
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