Help for the mathematically/astronomically challenged.

[Piscivore]

How far would a radio signal deliberately broadcast into space by an Ariceibo-type radio antenna get in fifty years? Out of the solar system? To Alpha Centauri?

[Tubbythin]

50 light years. Alpha-centauri is about 4.3 light years away according to wiki. So, yes to that (and the solar system obviously).

[Piscivore]

50 light years. Alpha-centauri is about 4.3 light years away according to wiki. So, yes to that (and the solar system obviously).

Radio travels at the speed of light?

[drkitten]

Radio travels at the speed of light?

Yes. In fact, radio is a form of light, just with a very long wavelength. But both visible light and radio waves are simply EM radiation.

[Jimbo07]

Radio travels at the speed of light?

what drkitten said, and:

The Electromagnetic Spectrum (http://en.wikipedia.org/wiki/Electromagnetic_spectrum)

[Piscivore]

Yes. In fact, radio is a form of light, just with a very long wavelength. But both visible light and radio waves are simply EM radiation.

Thanks. I think I knew that as an uncorellated factiod, but I didn't put that together with speed. I was under the impression somehow radio was a lot slower.

[ddt]

How far would a radio signal deliberately broadcast into space by an Ariceibo-type radio antenna get in fifty years? Out of the solar system? To Alpha Centauri?

You're thinking of the Arecibo message from 1974? The wiki article says it was transmitted with a power of 1000kW. As a follow-up question: at what distance would a radio telescope on another planet pick up this message - think of terrestrial conditions and current human technology for the other planet as well.

[Piscivore]

You're thinking of the Arecibo message from 1974? The wiki article says it was transmitted with a power of 1000kW.

Something like. Along the lines of, say, if a couple of techs got drunk/high/silly one night and decided the rest of the universe really needed to hear Jefferson Airplane, sort of thing.

[Mongrel]

Something like. Along the lines of, say, if a couple of techs got drunk/high/silly one night and decided the rest of the universe really needed to hear Jefferson Airplane, sort of thing.

Is this a purely hypothetical question? :wide-eyed

[Piscivore]

Is this a purely hypothetical question? :wide-eyed

Hypothetical, as in has it ever really happened, yes, it's hypothetical. As far as I know.

Hypothetical, as in may I someday do something fictiony with it, not so much.

[Madalch]

Something like. Along the lines of, say, if a couple of techs got drunk/high/silly one night and decided the rest of the universe really needed to hear Jefferson Airplane, sort of thing.

Wouldn't they be more likely to play Klaatu?
hsIcKVC7MqM

[insomneac]

Thanks. I think I knew that as an uncorellated factiod, but I didn't put that together with speed. I was under the impression somehow radio was a lot slower.

Perhaps because of the association between radio and sound?

[Piscivore]

Perhaps because of the association between radio and sound?

Yeah, most likely.

[CriticalThanking]

Just heard a bit on NPR Science Friday podcast that normal broadcast power is such that the inverse square law means none of the signals would be picked up past the edge of our solar system. They would get lost in the background "hum."

They also mentioned that because we are going to microwave communication (i.e. point to point such as to satellites), far less signal is being leaked to space. So even if they could hear us outside the solar system, we were only noisy for a few decades, then we started getting quiet.

CT

[Ocelot]

The speed of light in a vacuum is the same across the entire electromagnitic spectrum. As space is close enough to a vacuum as to make no odds that's what matters here. However through air radio waves are a shade faster than visible light. Though not so much as you'd notice. Longer wavelengths are not slowed as much when passing through a physical medium which is why they diffract less and how white light is dispersed (http://en.wikipedia.org/wiki/Dispersion_(optics))into a spectrum by a prism.

There is another effect in operation whereby the music that reaches me though one part of the frequency spectrum (88.60 MHz) appears to be 20 years older than that which reaches me through a higher frequency (99.7 Mhz) despite originating from the same transmitter. :D

[Piscivore]

Just heard a bit on NPR Science Friday podcast that normal broadcast power is such that the inverse square law means none of the signals would be picked up past the edge of our solar system. They would get lost in the background "hum."

They also mentioned that because we are going to microwave communication (i.e. point to point such as to satellites), far less signal is being leaked to space. So even if they could hear us outside the solar system, we were only noisy for a few decades, then we started getting quiet.

CT

And given that a lot of the material of that time was related to nuclear war, what are they going to think? :)

There is another effect in operation whereby the music that reaches me though one part of the frequency spectrum (88.60 MHz) appears to be 20 years older than that which reaches me through a higher frequency (99.7 Mhz) despite originating from the same transmitter. :D

Okay, I actually got that. :D