Radio-waves,light and etc...

[Energy]

I was wondering, is there a limit on how far radio waves can travel? Is there ever a point where a radio wave signal disappears completely, and can't be recovered no matter how powerful the receiver is? For example, my computer's wireless network card and the wireless receiver connected to my other computer both have a maximum distance of 1 mile. This means that if I moved the computers more than one mile apart from each other, I would not be able to send a file from one computer to another. However, if I had a stronger receiver on my other computer, would I be able to increase the distance the computers could be apart, or would the radio wave transmitted by my computer completely disappear after one mile?
Everything should have limits even radio-waves!
Can radio-waves,when outside of an magnetic fields forever dissapear and lose information of an radio-signal of Discovery Channel,for example?

Some say there is no general limit on how far electromagnetic waves (radio waves) travel. However, due to absorption in the air and the fact that radio waves do not travel in a straight line but spread out in all directions the intensity of the signal will be reduced with increasing distance. The intensity I(d) at distance d should in a 1st approximation behave something like I(d) = C/d² * exp(-kd), where C is a constant that depends on the power of your sender and k is a constant that describes the absorbtion in the air.

so as the intesisty of your signal is reduced with increasing distance you have two options to still read the signal:
a) A better reciever. The better your reciever the smaller signal intesities you can still recieve. Due to background noise there shoudl however be a lower limit to the intensities you can recieve. I´d guess that today´s recievers are able to reach that lower limit. Below that level you can still detect the signal by filtering if you have some information on it before (like knowing it´s a periodic signal) but that´s another topic.
b) A more powerful sender. Given an unlimited power source you could simply increase the original power of your signal so much that it still has sufficient intesity when it reaches the reciever. Theoretically you can send any distance given a sufficient power source.

To sum it up: The signal your one computer sends does not completely dissapear but it´s intensity will be so low that it becomes undetectable due to background noise.But even radio-signals,radio-waves couldn't last forever!
Right?
Thanks everybody!

[liberdave]

You are right, in a nutshell. Think about radio waves. They are just waves. You and I can look at the night sky (with incredible aid) and see the "transmission" of waves (light waves are just longer light waves) that have been sent for (almost) eternity. A waves only "enemy" is the Doppler Effect. But, it will only serve to distort the wave. (That would be a neat experiment, see how the Doppler Effect effects radio waves!) Waves are highly resilient, look at gamma waves and their relationship to black holes.
With your computer model, the only logistics problem I see is FCC regulations on your transmitter (ack!). I bet you'd find some spoil sport in the FCC that'd find a way to piss on your parade. But I do think a more powerful transmitter would prove to be more useful. A more powerful receiver can't receive a signal that can't be pushed hard enough. I'd opt for the higher transmitter so then you don't have to worry as much about terrestrial obstacles. But the down side is the amount of power used goes up exponentially.
So to sum it up. Yes, radio waves do last for ever. Remember: wavicles have mass sometimes!
Either this is right or I have no f***ing clue what I'm talking about.

[Protostar]

I wonder, since you can REFRACT light, can you refract sound using the same type of method? (sorry to intrude) but I was just wondering.

[liberdave]

I wonder, since you can REFRACT light, can you refract sound using the same type of method? (sorry to intrude) but I was just wondering.

Well yes and no. Remember two things, first, light is part of the electromagnetic spectrum; sound is a function of energy transfer through a medium. OH and of course remember sound must have a medium to travel through (air, water, dirty socks stuffed in bleeding mouths). When you refract light, you are changing the medium. The light only "bends" because the speed the light is traveling in a certain direction has changed (not the frequency, if the frequency changed the color would change). If you want to hear sound "refract" all you have to do is try to talk through a fan. The blades change the direction the sound travels and distorts frequencies. It's harder to actually refract sound because it only travels in waves (not like light which is dual natured and travels in both waves and particles). But if you could maybe change the density of the medium the radio waves travel through (which would imply the existence of an aether. ha. who want's to debate that one with me?), you could somehow achieve a refraction of some kind.

An interesting side note: During a full solar eclipse astronomers found that they could "see" stars that geometrically and astronomically they shouldn't have been able to see because they were positioned directly behind the sun! What they detected was the light traveling around the sun! The gravitational pull from the sun was able to bend the space-time that the light from the distant stars was traveling through. So it made it appear that the stars were actually to the side of the sun when they were actually behind it. So maybe radio waves "could" bend around a space-time distortion but it would only be relative to an observer in both the bend and outside the bend. You would need two observational methods.... OH sorry, I was rambling. Maybe Laz could help us out on this one... Hey Laz!!!

[Marajadex]

Excellent Post LiberDave. Very well said.

You have a very good grasp on physics and the ability to put it in terms that anyone can understand. Way cool!!!!!

[liberdave]

Well thanks! I just wish we had more conversation in here about this stuff!

[Mezurashi]

Once upon a time I heard a reference to Gravity Lensing Effects where if you have a telescope of sufficient resolution aimed at the right point you could see the stars Behind other stars due to their light being bent around something in the way. That something would require enough mass to cause the effect.

Radio waves, like all EM, loses energy as it propogates - BUT depending on signal strength the transmission could go on for a long, long time. 'Relative Infinity' is a term I like to use, where things aren't Infinite but from our POV they might as well be. Like the boundaries of the Universe or Dubya's Ability to be Idiotic.

Radio waves can also increase and decrease in frequency like all EM waves, but the effects are perceived differently by us in this thick soup we call air.

Whether or not Radio waves can bend isn't my quesition. It is, "Do radio waves behave similarly to other EM spectrum when bent around a gravity source?"

AND*** If one could build a Galaxy Sized 'Receiver Dish' with ultra sensitive detectors then one could, theoretically, pick out the secret messages from Ming The Merciless to his Berserker Fleets from the background noise of the universe. But you'd need Quantum Computing to decipher the mess out.

[Protostar]

Great Posts guys. And dave, you should lecture this stuff. That was AWESOME!

[Sabazi]

Remember: wavicles have mass sometimes!

They've made bucky balls to act as wavicles.

[Energy]

Once upon a time I heard a reference to Gravity Lensing Effects where if you have a telescope of sufficient resolution aimed at the right point you could see the stars Behind other stars due to their light being bent around something in the way. That something would require enough mass to cause the effect.

Radio waves, like all EM, loses energy as it propogates - BUT depending on signal strength the transmission could go on for a long, long time. 'Relative Infinity' is a term I like to use, where things aren't Infinite but from our POV they might as well be. Like the boundaries of the Universe or Dubya's Ability to be Idiotic.

Radio waves can also increase and decrease in frequency like all EM waves, but the effects are perceived differently by us in this thick soup we call air.

Whether or not Radio waves can bend isn't my quesition. It is, "Do radio waves behave similarly to other EM spectrum when bent around a gravity source?"

AND*** If one could build a Galaxy Sized 'Receiver Dish' with ultra sensitive detectors then one could, theoretically, pick out the secret messages from Ming The Merciless to his Berserker Fleets from the background noise of the universe. But you'd need Quantum Computing to decipher the mess out.

Actually,they should dissipate,but this really depends on how powerful madium is.If it's powerful as quasar,than it wouldn't dissipate that easily,but if it's like our radio-messages that we send to space sooner or later,it would dissipate much before.That's my opnion.Nothing lasts forever,not even radio-waves.

[liberdave]

Now my first post was assuming the vacuum of space being the medium. But of course this has a lot to do with the composition of dark matter. If DM is dust and such then yes, it will hinder the EM waves. If DM is really the prayers of blind children then no, the prayers of blind children have been proven not to hinder EM waves.

They've made bucky balls to act as wavicles.

Our reality is made up of wave-particle dualities. Take the periodic table for example. The information this table exudes is marvelous. It predicts the existence of elements by their position on the chart. This is an example of a particle or digital function because it can predict individual elemental properties in comparison to none others. It can also predict qualities of entire groups of elements (such as valence fields, polarity, groups etc...); which is a wave or anti-digital (analog) function because it provides an overall view concerning what an entire system of elements or body does in a variable manner. Empirical science is like a reversed Russian Doll, just when you think it can't possibly get any bigger, you find another shell to wrap around it.