Ask MetaFilter questions tagged with waves

The Diamond Age of Wireless

mouthnoize — Wed, 11 Nov 2009 09:24:03 -0800

I would like to understand the dynamics of radio waves like a bird understands air currents. What would be the best way as a middle-aged learner to gain this insight?

Some previous discussions indicate a degree in electrical engineering, but I'm pretty much done with academia - I'm looking for a more kinesthetic approach. I really want to intuitively understand the ways that radio waves bounce, jostle and jive!

Any thoughts appreciated! :)

How about them waves?

amethysts — Sun, 23 Aug 2009 18:07:22 -0800

Lawn Guyland filter: Does anyone know how long the big waves at Jones Beach and Robert Moses beach going to last? Are they still even around? How about tomorrow morning? How would I even go about finding this out?

So ET won't be picking up the Olympic Games in 1936 Berlin?

MrMulan — Tue, 12 May 2009 11:18:32 -0800

Do radio waves attenuate and become noise or do they go on forever? In Carl Sagan's Cosmos and his novel Contact, he writes how radio waves go on forever. I just finished seeing the Discovery Planet special "Life after People", where in the closing segment, the narrator states that new research has shown that radio waves probably attenuate after 4 light years to become nothing more than noise. This occurs because of cosmic dust, radiation, planetary systems, asteroids, ect.

I thought radio waves go on indefinitely in a vacuum, and space is mostly a vacuum because of the distances involved, even with all the cosmic dust and whatnot.

So has another cherished belief of mine hit the dustbin?

The inconceivable nature of nature

Eiwalker — Sat, 21 Feb 2009 11:41:38 -0800

How much do criss-crossing electromagnetic waves affect one another? Richard Feynman famously said this:

http://www.youtube.com/watch?v=AU8PId_6xec

The picture is that the electric field consists of a lot of jiggling, and that information is going every which way. In that case, when one stream of information is going one way, how much is it getting distorted by myriad streams that are passing right through it from other directions?

Drowning In Waves

Rykey — Wed, 13 Aug 2008 17:47:46 -0800

How densely is the air in populated places packed with invisible waves? How harmful is all that? So this question on AskMe, about places where you can't get a radio signal, got me thinking.

On the other end of the scale, say a city of 100,000 or more, how dense is the air with invisible manmade waves? Of course it would depend on exactly how big the population was, and how much wave-transmitting devices were in use there, but I can't help but imagine I'm cutting a path through a wall of micro-, sound- and other waves every time I walk around town.

Between analog and satelite radio and TV, cell phones, wireless computer signals, and all the rest, jeez, that's gotta be a lot of tiny waves. Are there any study results or theories (preferably geared toward the layperson) that discuss the harm all this invisible "pollution" might be doing to humans or other species? Could this sort of thing be part of the big bee disappearances, screwy bird migrations, etc.? What are some vocabulary words I need to know to even do a search on this sort of thing ("transmission pollution?")?

Not paranoid-- just curious.

How do I find the lack of radio waves?

mdbell79 — Thu, 17 Jul 2008 06:06:24 -0800

What town in the United States has the lowest amount of detectable radio waves? Obviously, there are a lot of places (or used to be, anyway) where you can't get anything to come up on the radio dial. Which of those places would have the absolute least radio? As in, even though there are maybe hundreds of remote locations in the US (and let's say the continental US, because Alaska is probably the winner here anyway) where it's impossible to pick up anything listenable, would there be any place where there wasn't any radio that could even be detected?

Is there even a way to find this out?

Even better, is there any way to find out what the answer would have been in 1970? 1980?

I'm thinking mainly commercial AM/FM radio, and I don't even have a clue how to start looking into this. I figured that if anybody could help me figure it out, it'd be the metafilter crowd. If you need more information about what I'm looking for before you can help, I'd be glad to offer what I can. This is research for a project I'm working on, and although it's not vital it's a detail I'd like to be able to incorporate.

Video of Space Waves

wavejumper — Thu, 17 Jan 2008 15:23:54 -0800

Can you think of any good video clips of waveforms in space that you've seen? They don't necessarily have to be copyright free (this is for a personal project), but they do need to be good quality and accessible to me within a few days - I'm doing this project at DVD resolution, 720 X 480... Specifically, I'm looking for a match to this shot.

To communicate the connection between "cosmic waves" :-) and the most impressive ones visible on earth - ocean waves.
I could use explosions, supernovas, math renderings, whatever as long as it could match up with an ocean-wave shot.
Thanks!

radio waves

amsterdam63 — Sat, 29 Dec 2007 12:17:45 -0800

How do radio waves travel through walls? I assume the waves penetrate a solid at the microscopic level, causing them to vibrate at the frequency of the wave which then travels into the enclosed room, but I really have no idea.

Infinity and beyond

euphorb — Fri, 19 Oct 2007 21:12:36 -0800

What happens at either extreme of the electromagnetic spectrum? What lies beyond gamma rays and radio waves? Is there a limit on frequency, either theoretical or practical? Can there be a radio wave with a wavelength nearly equal to infinity or a gamma ray with a wavelength nearly zero? What would be the properties of these waves?

Waves

schroedinger — Tue, 17 Oct 2006 22:15:26 -0800

Recommendations for good explanations of waves and vibrations. I'm taking a college-level course (includes DiffEQ and some linear algebra) on the physics of waves, and it's completely stumping me. I need help parsing the topic as a whole. Much Waves do not seem to offer the simplified generalizations that come so easily to classical mechanics, electricity and magnetism, and special relativity. I understand the derivations for the formulas and solutions for damped harmonic motion, forced harmonic motion, finding the quality factor, etc, but it doesn't all make sense, and therefore I can't apply it to real-world problems.

I'm not sure how to explain this. With the other physics topics I've mentioned, I can see the big picture and apply the formulas to real-world problems and understand how and why I'm using that formula over another one. With waves, I don't see any overall picture, just a bunch of seemingly ridiculously over-complicated formulae that only barely fit together. I don't know if this is just how waves is or whether it's the presentation. Right now I've gone through HRK, Feynman's Lectures, and Pain. Can anyone point me to other oresources or techniques they found especially useful?

How can I tell if my microwave is safe?

louigi — Tue, 20 Jun 2006 06:12:35 -0800

How can I tell if my microwave has become unsafe? When my microwave is on it seems to interfere with both my cellular reception and the signal quality of the portable phones in the house. This makes me a little worried that whatever sort of protective lining is on the microwave isn't doing its job of stopping the harmful rays. How can I know whether this is needless paranoia? The microwave is rather new.

Aside: I've heard that if the protection is of proper strength then a cellular phone, placed in the microwave, should not ring when called; seems like it could be true, and equally plausibly could be total nonsense. But mine does ring in there.

Flourescent strips, pulsing lights and a chiller cabinet.

twine42 — Fri, 28 May 2004 05:43:34 -0800

A random question involving fluorescent strips, pulsing lights and possibly a chiller cabinet. [MI] Last night I spent some time watching a chilled cola vending machine. It had a glass front and a pair of strip lights inside the case.

Every now and then I was aware of the noise of a fan running with a pulsing speed at about 2 - 3 Hz. Whenever it happened I was aware of a strange pulsing of light down the tubes. 'Dark' spots of light were being created on each audible pulse and then flowed down the tube to be sucked back in at the other end in perfect syncronisation with the creation.

The pulses of 'light' and 'dark' were apparently the same size and travelled quite slowly. There were probably about 30 bands down a four foot tube. I'd guess that the air inside the vender was in the 2-6 celcius area.

To make things worse, I'm not 100% convinced that the sounds wasn't coming from a coffee vending machine on the opposite side of the room.

What the hell was going on?