Whose Time Frame For Signal Repeat - Ours or ET's


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Profile BioTrek47
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Message 1390241 - Posted: 12 Jul 2013, 20:52:50 UTC

What is the accepted time frame for the repetition of an ET signal? I looked for the answer to this and only find vague references that state a true positive candidate must be acquired repeatedly. Suppose a signal meets all the requirements, i.e. is not earth-based interference, is not a natural source, appears in all ways to be a signal from intelligent beings, etc., etc., etc., EXCEPT it only occurred one time (since the start of SETI). Perhaps it only repeats once every 100 (Earth) years. Or 1000 years. We don't know ET's time frame. Possibly many of the most tantalizing signals that have not yet repeated may indeed be true positive candidates.

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Message 1390406 - Posted: 13 Jul 2013, 14:38:06 UTC
Last modified: 13 Jul 2013, 14:39:17 UTC

Yes, it has happened several times, that a signal was heard only once, and could not be identified as anything other than a genuine ETI signal. The Ohio State University 'wow signal' is the most famous of these. The scientific position is that without repeated reception, the signal can not be confirmed to be from an ETI and can not be confirmed by independent observers. It remains in a grey area, not provable, but definitely very interesting.
The 'wow signal', or any 'one-time' signal source could be tested for infrequent repetition by keeping it under continuous observation. As the 'wow signal' was quite strong, it could be monitored in this way by three quite modest radio observatories, separated by 120 degrees of longitude, to give continuous coverage.

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Message 1390548 - Posted: 14 Jul 2013, 5:36:17 UTC

If a signal only occurs once every hundred years from an intelligence then its an odd one. The telescope travels over a point in space quickly. we look at 107 second long segments of that data to determine if there is a repetitive signal. The data is checked for "fit" and stored. Good signal candidates are checked against other candidate signals from the same area of the sky on different days/times to check for additional signals.
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Message 1390585 - Posted: 14 Jul 2013, 10:31:04 UTC
Last modified: 14 Jul 2013, 11:19:07 UTC

The scientific position is that without repeated reception, the signal can not be confirmed to be from an ETI


I tend to strongly disagree. I believe that we are too far away from any putative alien civilization to hear a spurious signal such as television or radar. Any contact would therefore be a beamed message containing easily detected intelligence. We would have to eliminate the possibility that the signal had an origin on Earth. I presume that telescopes working in unison around the world, on the moon or in space could do this.

Since "THEY" also would also not know we are here THEY would be randomly focusing and slewing a beam at different spots in their sky. So: do I infer that we are throwing away countless signals without looking for signs of intelligence.

An explanation is needed as to why anyone thinks such a signal would persevere; originating from a constant source . Are we here on Earth broadcasting a powerful beam of "we are here" to a fixed point in the sky?

Please enlighten me if you think my logic is flawed?

Since we have been eavesdropping for 50 or more years with no results, shouldn't this modality of search be discontinued. Can we conclude that there is no civilization within an eavesdropping detectable range from us. If they are 30,000 light years away could we detect a spurious, non focused signal of a few million watts. (TV or Radar say) ??

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Message 1390590 - Posted: 14 Jul 2013, 10:48:06 UTC

An explanation is needed as to why anyone thinks such a signal would persevere; originating from a constant source . Are we here on Earth broadcasting a powerful beam of "we are here" to a fixed point in the sky?

Please enlighten me if you think my logic is flawed?

Just because we AREN'T doesn't necessarily mean that no-one else IS.

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Message 1390592 - Posted: 14 Jul 2013, 11:06:22 UTC - in response to Message 1390590.
Last modified: 14 Jul 2013, 11:10:46 UTC

Just because we AREN'T doesn't necessarily mean that no-one else IS.


My point exactly. Explaining why someone out of eavesdropping earshot (range) cannot hear us and would never know that we are here . Since we would have no idea where anyone out there was; we would have to fire randomly in the dark (so to speak). Sending a beam in a fixed and constant direction makes little sense. We would want to maximize the chance that someone might detect the signal that we are, in fact, in existence by firing in as many directions as possible. This would be done one-at-a time in short powerful bursts in order to focus our energy in an economic fashion.

Apparently we do not wish to hold up our end of the bargain in the SETI game.

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Message 1390610 - Posted: 14 Jul 2013, 13:11:26 UTC
Last modified: 14 Jul 2013, 13:12:08 UTC

we fired only ONCE in our lifetime of our humanity :P

if our signal has been capted, and checked if it would be repetitive...

we never repeated it :P

so...

we DONT exist.
Do we exist ??
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Message 1390737 - Posted: 14 Jul 2013, 22:23:49 UTC - in response to Message 1390610.
Last modified: 14 Jul 2013, 22:24:56 UTC

we fired only ONCE in our lifetime of our humanity :P

if our signal has been capted, and checked if it would be repetitive...

we never repeated it :P

so...

we DONT exist.
Do we exist ??

For the repetitive very high power stuff, we have various air defense radars running continuous sweeps.

Going down the power scale, we have such as microwave links and TV transmissions that can reach a few star systems before getting lost in the cosmic background noise.

Granted: We are not sending any intentional repeated signals for ET to pick up. Part of the SETI question is what proportions of civilizations would want to, when in their evolution, and for how long...


Keep searchin',
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Message 1390756 - Posted: 15 Jul 2013, 0:37:20 UTC - in response to Message 1390737.


Part of the SETI question is what proportions of civilizations would want to, when in their evolution, and for how long...


Keep searchin',
Martin



None.
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Message 1390790 - Posted: 15 Jul 2013, 4:22:27 UTC

To an alien race whose time frame reference is different from ours repetitive could have an entirely different meaning.
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Message 1390802 - Posted: 15 Jul 2013, 4:48:30 UTC - in response to Message 1390790.

time frame is based on your planet making a complete turn around your sun

= 1 year.

how long lives a being , it s something else, genetic
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Message 1391010 - Posted: 15 Jul 2013, 18:41:41 UTC - in response to Message 1390802.

actually ours is 24 hours. we can make a complete rotation of our planet in 24 hours more or less. Now the minute portion of the sky obscured and lensed by our sun is a different matter.
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Message 1391098 - Posted: 15 Jul 2013, 22:23:35 UTC - in response to Message 1390756.
Last modified: 15 Jul 2013, 22:23:45 UTC


Part of the SETI question is what proportions of civilizations would want to, when in their evolution, and for how long...



None.


Sorry, no go on that one. Too absolutist.

Keep searchin',
Martin
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Message 1391100 - Posted: 15 Jul 2013, 22:34:39 UTC - in response to Message 1391010.
Last modified: 15 Jul 2013, 22:37:27 UTC

actually ours is 24 hours. we can make a complete rotation of our planet in 24 hours more or less. Now the minute portion of the sky obscured and lensed by our sun is a different matter.

An interesting thought from that...

Our laws of physics and biological chemistry make our "1 second" a reasonably small unit of duration and we have adult lifespans of less than a century.

Other creatures on Earth can have fleetingly brief lives of less than a day that is wholly devoted purely to just the continuation of their species. Yet other creatures can live for centuries...

And then we now have machines that can usefully 'appreciate' across the scale of timespans from microseconds through to longer than our own lifespans.


So what of aliens?

Life arising inside a huge gravity well? By the power of General Relativity, they would see our existence as a fleeting flash whizzing by as they watched the galaxy itself evolve around them...

To us, they would appear as a once-in-a-thousand-years event for a repeated signal even if they repeated their transmissions every day in their timeframe.


Conversely, are there other areas of physics/biology whereby life is greatly accelerated? Must all great communities come to an end?

The record for survival must go to the Galifreyans for their 10 million+ year supreme reign followed by their eternity lost in a time lock!


Keep searchin',
Martin
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