h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Yes Flake... you!!

Can say I have, old boy. Any good?

Analiese: All-knowing... perhaps I've come across that way. My background in both waveform theory and digital devices is quite extensive. The guys who work for SETI know this stuff even better than I do.

Condescending and arrogant... in my last post, in the last paragraph, certainly. Before that, I don't see it. I suspect that it was more of a perception on your part than any particular wording on mine.

Admit no criticism... I don't see that, either. For instance, I did acknowledge the possibility that we might not recognize intelligence when we receive it.

For my part, I have neither argued for nor against the SETI project. I have only endeavored to explain it.

Be nice to me when you formulate your response... I have a pie...

Oh well Flake... you can't help me on my conundrum then... guess I'll have to read that bit again when I'm less distracted...

But yes, it is good... I'm only on the 2nd chapter but it is easily read , for a non-science type like meself... It basically covers all the cutting-edge quantum theories as to the make-up of the universe... the Many Worlds Theory is quite mind blowing...

Pie.

Incidentally, check out www.highliftsystems.com

Your last post was what I responded to, Mr. Mugwump, in my immature way. And, yeah, you pissed me off just a little, but its okay now probably. Just remember, though. Even though you might have a pie, I got a whole big, hot kettle of chili which you can eat or wear depending on how you behave or don't behave. AAAYYYY!!!

Okay, so now what?

Well, let's look at that radar 30 degree shift thing you mentioned. Is that like polarization in visible light? And why would it ionize the atmosphere? Is that sort of like lightning on demand?

And speaking of lightning, what sort of RF accompanies that?

And you still haven't commented on whether or not it would be possible to encode interference patterns, or maybe you have and I just missed it?

And what about the role of electromagnetic theory in all of this?

Does current invariably flow from positive to negative as some electrical engineers have asserted or does it really matter?

And what does the "right-hand rule" actually depict in terms of electro-magnetic phenomena? Is it a mathematical convenience or something more substantial?

And how do frequencies determine what we can perceive?

See how I'm just full of impertinent questions and nowhere else to go with them?

I guess I'd better do that thing where you basically quote the entire post, sprinklinkg answers where pertinent, else I become accused of impertinently ducking impertinent questions...

"Well, let's look at that radar 30 degree shift thing you mentioned. Is that like polarization in visible light? And why would it ionize the atmosphere? Is that sort of like lightning on demand?" - Sorta. Not sure. No.

Okay, maybe I'd better expand those a bit... :

"Is that like polarization in visible light?" - This gets us into that tricky bit about light being both a particle and a wave... or is it? That debate is not one I'm qualified to entertain... you'll have to bug one of our resident quantum physicists for that one. But an RF signal is definitely just a wave. The way it's like polarization of light is, you can switch from negative to positive light... you've probably played with that on a photo editor. That's very similar to shifting an RF wave 180 degrees. However, just like in the photo... the RF wave still looks pretty much like it did before you reversed it.

"And why would it ionize the atmosphere?" - We're already causing atmospheric particles to vibrate a bit with each wave... the electrons swing toward the source during the positive part of the cycle, then swing back away during the negative part of the cycle. That molecular vibration is how a microwave cooks food. If you had an RF wave with an overall polarity of +, then all the particles it passes through would remain polarized, rather than swinging the electrons back over to the other side. Anything that could do this would probably require about 100 billion tera-f**k-watts of power.

"Is that sort of like lightning on demand?" - In science fiction, I suppose. But as I've illustrated with the power requirements, it's not really possible.

"And speaking of lightning, what sort of RF accompanies that?" - Lightning creates the sort of electromagnetic field one would expect whenever current flows. But a bolt of lightning would have to repeat thousands of times a second to turn that EM field into an RF wave. An RF wave, by its nature, cycles thousands-billions of times per second... that's what the frequency part of it denotes. 1 cycle/second = 1 Hz.

"And you still haven't commented on whether or not it would be possible to encode interference patterns, or maybe you have and I just missed it?" - I think I missed this one. Encoding interference patterns... I'm not sure what you mean by this.

"And what about the role of electromagnetic theory in all of this?" Take an electromagnetic field, and cycle it + to - several times per second, and you've created an RF wave. So it goes hand in hand. The EM fields in space are a huge source of electromagnetic interference, which is the biggest problem the SETI project faces... although interference from human RF communications are actually a bigger problem than spaceborn fields.

"Does current invariably flow from positive to negative as some electrical engineers have asserted or does it really matter?" - As someone who has found himself standing at the negative end at the wrong time, let me assure you that it is an immutable law of the universe. Unless you're talking about that silly "hole flow" school of teaching, where you follow the holes moving from negative to positive. My school told us a bit about hole flow theory, we had a good laugh, and then we got back to the business of following electrons.

"And what does the "right-hand rule" actually depict in terms of electro-magnetic phenomena? Is it a mathematical convenience or something more substantial?" - Oh ye Gods! What have I done to deserve this?!

Thr right-hand rule is one of the absolute basics of RF... in other words, it's the kind of thing you learn to pass the test in school, and promptly forget, because you don't find much need for it in practical situations... unless you're an engineer designing radars or something. You hold your right hand out with your thumb, index, and middle fingers at 90 degree angles from each other... thumb and index finger like you're making a pistol, middle finger pointing at yourself. One of the fingers represents the wire, another represents the EM field it will create, and the other finger represents... oh, I give up. It was 10 years ago. Anyway, it's one of those mathematical conveniences that turns out to be universally true, so engineers go around making their own version of the Vulcan greeting all the time to figure out how to install the waveguide.

"And how do frequencies determine what we can perceive?" - Shorter wavelengths, and thus higher frequencies, suffer greater attenuation as they travel. So lower frequencies would give us a better chance of getting something we can read across interstellar distances... although it's not so much of a much when you're talking about space... there isn't much there to attenuate it.

And of course, the more junk their is on a frequency, the harder it is to get a clean signal. All that hydrogen rubbing together out in space at 1024 MHz or something really kills that signal... same with that crap radio station in my area broadcasting at 99.1 MHz.

Okay, thanks, now we're getting somewheres.

Like it's my understanding that light, and I would presume the frequency doesn't especially matter so maybe we should just call it electromagnetic radiation, essentially vibrates in all directions around the axis of propagation. It has two vibrational components, one electrical and one magnetic at right angles to each other, but the whole waveform is essentially vibrating in all directions around that axis like I said.

When this waveform encounters polarizing material, which is essentially a film that causes interference, all but one of the multiple axes of vibration are eliminated. The resulting waveform is said to be polarized.

Now when it encounters another piece of polarizing film, if the film is oriented the same as the first film, the polarized radiation is transmitted however if it is oriented perpendicular to the first film, then the polarized radiation is totally blocked. If it is oriented at any other angle then the radiation is more or less reduced, which is why a couple of these films are often employed in dark glasses.

Now, is there some device that can do to RF what the polarizing film does to visible light? Some interference device? Since I'd presume the principle would be the same?

This also brings up what you were saying about the right-hand rule. An electrical current generates a magnetic field and an electrical field at right angles to each other and the conductor of the current in a rather predictable orientation.

Now, why there should be distinction between magnetic and electrical fields is sort of beyond me since they pretty much behave the same, but apparently it's the relative angles that matter. Maybe that Maxwell guy knew about it since I think he was the one who came up with the theory in the first place.

Anyways, what I've been trying to imply in this excursion around our intellectual barn here is that somebody might have figured out a way to polarize RF and if they did, they could modulate that polarization maybe, so that in its simpliest, binary form, transmission would be a one and blockage would be a zero, but then you can have all those angles inbetween to represent additional coding. You wouldn't actually be toying with either the amplitude of the wave or the frequency, just the orientation.

What do you suppose the ramifications of that might be?

On second thought, and after looking at it a little while, I think I can see that what's happening is a form of amplitude modulation by filtering rather than by adding strength to the osillating field. Because as I rotate that film in my head, it seems like it's progressively blocking more and more of the polarized waveform until I hit perpendicular when I've completely blocked it.

Not only am I immature but not a little dense. Buh!!!

Still my gut tells me something about this needs to be examined a little bit more, but then who needs somebody who thinks with their guts? Oh well, if my gut didn't hurt my head would.

Okay, what if I do this? I rotate the second film at a certain rate. Doesn't that impose some sort of frequency modulation on top of the amplitude modulation? And if it does, so what? Now my head really hurts and my gut is a goner.

No, it doesn't. It's kind of like if I had a light and a wheel with slits in it rotating except the polarizing film would produce more gradual fluctuations in the light than the slits would, that's all.

Big deal, Analiese!!

Okay back to the drafting board. How about interference rings? I could vary those couldn't I?

Oh nevermind! I need to go have sex or something.

Mugwump

ALL EM signals/radio waves etc ARE streams of low or high energy photons. This is very basic physics.
And consequently all radio waves have a particle nature.

I agree! Get that man a pie!

I already ducked that argument in regards to light... you won't drag me into it on RF.

Ah c'mon, Mr. Mugwump. Nobody'll notice if you get dragged in and then we can debate what Debroglie meant when he said an electron had a wavelength right?

Wouldn't it be funny if the aliens were using gravity waves instead? Or maybe just yelling really loud? Or using a finger or tentacle alphabet? Or that funny looking light organ in Close Encounters of the Third Kind? Or even cosmic tomtoms? Or cellphones under bridges? No wonder they can't contact us right?

But you're forgetting one important factor Analiese: They don't exist.

I am subtle.

Yeah, I know, Flake. When I close my eyes or turn off my laptop, you don't exist either, but I've found ways of working around that subtlety.

Ah, that old chestnut.