PDA

View Full Version : Analog science article



Tom Mazanec
2013-Dec-14, 07:21 PM
Please let me suggest you try to get ahold of the March 2014 issue of Analog Science Fiction/Science Fact.
The fact article makes a good case that the optimum system for interstellar communication at our level of technology would be the 1064 nm neodymium laser.

Noclevername
2013-Dec-14, 09:00 PM
And I assume the implication is that we should be looking for such emissions, or transmitting signals with such a laser?

Does the article give specific reasons for selecting this frequency?

Tom Mazanec
2013-Dec-15, 12:38 AM
Yes to both questions.

Noclevername
2013-Dec-15, 12:59 AM
And what were those reasons?

Tom Mazanec
2013-Dec-16, 01:02 PM
Ahhh, Noclevername, please purchase a copy, in hardcover or e-book, or borrow one from a friend or library.
I cannot retype half the article, both because I am a mediocre typist and because of copyright issues.

R.A.F.
2013-Dec-16, 02:37 PM
Please let me suggest you try to get ahold of the March 2014 issue of Analog Science Fiction/Science Fact.
The fact article makes a good case that the optimum system for interstellar communication at our level of technology would be the 1064 nm neodymium laser.

A google search for the author of that article...one Mark H. Shellans, lists nothing remotely relevant to interstellar communication.



The March 2014 issue of Analog can be bought on line, here (http://www.magzter.com/US/Penny-Publications,-LLC/Analog-Science-Fiction-and-Fact/Fiction/32559), although I don't know why I should be expected to buy this, in order to discuss this...

Tom Mazanec...can't you summarize the article, and discuss it here, as opposed to us all having to purchase it?

Paul Beardsley
2013-Dec-16, 02:53 PM
Whereas I think Tom could have supplied a little more information about the article, it's reasonable to simply recommend something that might interest people here. After all, it's not as if he's presenting an ATM argument and insisting people buy something in order to counter his argument.

Tom Mazanec
2013-Dec-16, 08:10 PM
Well, I am reluctant to summarize too much, because that is not fair to the author...I may be distorting in the condensation, but I will give it a shot. Mark H. Shellans argues that a civilization would try for as many contacts as possible, and hence would ping stars using the earliest method that a culture will develop to communicate a large amount of data at interstellar distances. This argues for high frequency for a wide bandwidth. He calculates that a 10,000 MHz signal using a 100 meter radio telescope at two million Watts could reach an equivalent system at only 1/10 light year. Next, he looks at laser, which he says is better because the short wavelength allows narrow beaming and higher data rate. First he looks at the Nd:YAG laser, which exists up to 100 kW, fed through the W. M. Keck with a bandwidth of 10 MHz has a range of 9.9 light-years. An extension of Keck allows 1 GHz bandwidth and 123 light-year range. Since range scales directly with frequency, but only as the square root of power, a CO2 laser would have to be huge (with huge cooling problems) to equal this. Shorter wavelengths at sufficient power are beyond our technology.

Noclevername
2013-Dec-20, 04:11 PM
Well, I am reluctant to summarize too much, because that is not fair to the author...I may be distorting in the condensation, but I will give it a shot. Mark H. Shellans argues that a civilization would try for as many contacts as possible, and hence would ping stars using the earliest method that a culture will develop to communicate a large amount of data at interstellar distances. This argues for high frequency for a wide bandwidth. He calculates that a 10,000 MHz signal using a 100 meter radio telescope at two million Watts could reach an equivalent system at only 1/10 light year. Next, he looks at laser, which he says is better because the short wavelength allows narrow beaming and higher data rate. First he looks at the Nd:YAG laser, which exists up to 100 kW, fed through the W. M. Keck with a bandwidth of 10 MHz has a range of 9.9 light-years. An extension of Keck allows 1 GHz bandwidth and 123 light-year range. Since range scales directly with frequency, but only as the square root of power, a CO2 laser would have to be huge (with huge cooling problems) to equal this. Shorter wavelengths at sufficient power are beyond our technology.

This seems to assume a technological tree identical or at least extremely similar to ours. What if the hypothesized ETI invents CO2 lasers first? Or if their technology otherwise leads to other frequencies being more easily achieved?

R.A.F.
2013-Dec-21, 04:00 AM
Whereas I think Tom could have supplied a little more information about the article, it's reasonable to simply recommend something that might interest people here.

If you say so....certainly ain't gonna argue about it...

SkepticJ
2013-Dec-21, 05:25 AM
This seems to assume a technological tree identical or at least extremely similar to ours. What if the hypothesized ETI invents CO2 lasers first? Or if their technology otherwise leads to other frequencies being more easily achieved?

Or they had a similar tree to ours, but their technology is, say, thousands of years (or much more) beyond ours. The odds of independently-evolved beings that are at basically the same level of technology in planetary systems so close together in space and time has to be some high order of improbability.

The assumption that they would begin to communicate as quickly as possible is also a shaky. Maybe they would decide to wait until they had developed something much better. What's the rush? We're not shining lasers at our neighboring star systems.

Noclevername
2013-Dec-21, 01:07 PM
Or they had a similar tree to ours, but their technology is, say, thousands of years (or much more) beyond ours. The odds of independently-evolved beings that are at basically the same level of technology in planetary systems so close together in space and time has to be some high order of improbability.
The OP specifically says "at our level of technology". That's what I was responding to.


The assumption that they would begin to communicate as quickly as possible is also a shaky. Maybe they would decide to wait until they had developed something much better. What's the rush? We're not shining lasers at our neighboring star systems.

Agreed, but for different reasons. Why would they want to signal at all? What would their motives be? The assumption seems to be that they're like us psychologically as well and will consider other species as someone to communicate with.

R.A.F.
2013-Dec-21, 02:10 PM
What's the rush? We're not shining lasers at our neighboring star systems.

Precisely. Assuming another civilization (has done/would do) so when we have not is making an unreasonable assumption in my opinion.


...and I'd still like to know more about Mark H. Shellans. Why relevant information about him is so difficult to find, I do not know.

Tom Mazanec
2013-Dec-21, 10:44 PM
Of course, this logic would make any SETI search dubious, since we are not broadcasting radio into space at an intensity our radio telescopes could detect even from the nearest stars.

Trakar
2013-Dec-26, 06:27 AM
Or they had a similar tree to ours, but their technology is, say, thousands of years (or much more) beyond ours. The odds of independently-evolved beings that are at basically the same level of technology in planetary systems so close together in space and time has to be some high order of improbability.

The assumption that they would begin to communicate as quickly as possible is also a shaky. Maybe they would decide to wait until they had developed something much better. What's the rush? We're not shining lasers at our neighboring star systems.

Which many intelligent and quite reasonable people tend to think is a good thing!