Thread: "The Great Silence"

Originally Posted by Syme

Sure you have heard of them, they just aren't usually called "rasers". They are usually just called "RF masers". Many masers emit on radio wavelengths.

Uh-huh. You might want to check the wavelength range of rf lasers and masers. And yeah, a true "Radio Amplification by Stimulated Emission of Radiation" device would be called a "RASER."

Sure, masers might emit what are technically radio waves, but they are just on the border between radio waves and microwaves. They aren't the sort of radio waves we're talking about here. It's not like radio waves are as narrow a band of wavelengths as visible light.

Okay, I just saw an experimental 128 km "laser" that's been made, but if that is really a radio-aser, then it is hardly ready for practical use.

Although I have read (can't recall where) that lasers for interstellar communication might actually be visible-light.

Well that's fine. The fact is that no laser, maser, or blank-aser can stay collimated for interstellar distances. If you can find one that can, I think you'd be a candidate for a Nobel Prize.



But since you're obviously expert on all this, I'll just leave this thread.

Did I say something to piss you off? I'd be happy to have your input here, you almost certainly know more about some of this stuff than I do. I explained my understanding of collimation, but also freely admitted that it's a layman's understanding and I could easily be wrong. It sounds like you are telling me that laser beams do in fact de-collimate over distances. Is this correct? I did not know that but certainly don't pretend that means it isn't true.

And yes, I know that "raser" would indeed be the proper name for an RF maser. Along with grasers and irasers and all that. But in practice you are much more likely to see an RF maser called just that, an RF maser, rather than a "raser" (as far as I can tell it's rare for anyone to actually use those frequency-range-specific laser terms). I don't know anything about the wavelength range of RF masers; if you do, please tell me. I said what I said because I do know that there are RF masers, distinguished from 'normal' masers because they emit in what's normally considered the true radio spectrum rather than microwaves, HF radio though it may be. You asked about rasers, I told you that. If you had meant "rasers operating below a certain frequency", you should have said so.

EDIT: Also, if you poke around on google a bit, you will find plenty of serious discussions about the advantages of using lasers for interstellar communication.
http://adsabs.harvard.edu/full/1992lbsa.conf..637S
http://www.coseti.org/ross_02.htm
http://oreilly.com/catalog/alien/chapter/ch07.html

In fact apparently there is a whole parallel SETI effort, called OSETI, focused on looking for optical communications from other star systems instead of radio signals. Again, the lasers considered are usually actually visible-light lasers, so the problems of making a raser that operates on long wavelengths is probably irrelevant.