Ironically, after a brief spell of broadcasting our existence with powerful radio and radar waves, we're gradually shutting down the big transmitters for reasons of economy and efficiency. Satellites allow us to accomplish the same end with much less power than the old high-powered transmitters, and GPS-guided aircraft makes more sense that long-range radars for all but military purposes.
There are those who argue that we should transmit the basic facts of our existence with high-powered radio transmitters and lasers, and await a reply. Others argue that we shouldn't. Both arguments have merit.
We are already doing it(http://en.wikipedia.org/wiki/Arecibo_message). We are also sent a probe with heck lot of details on it(http://en.wikipedia.org/wiki/Voyager_Golden_Record).
>>This is actually an active debate topic among those who think about stuff like this.
True, but we have always been sending radio signals in space and probably will continue to.
Yes, absolutely. It is said that, because of radar, we're the brightest object within several light-years in those wavelengths. Add to that the periodic nature of radar, and we're signaling with an obviously unnatural beacon for anyone willing to listen.
I'm just saying the debate goes on, even though we're providing quite a beacon for anyone interested in detecting signs of semi-intelligent life. :)
> True, but we have always been sending radio signals in space and probably will continue to.
I wouldn't say "always". The first reasonably strong, narrow-band radio signals commenced in the 1920s. Not even 100 years. And we're quickly reducing our EM radiation footprint for economic reasons unrelated to anything resembling policy.
I see the point of both arguments -- that we should, and shouldn't, broadcast our existence. I actually prefer the "should" argument overall, considering the difficulty that an alien species would have getting here. We might learn something remarkable from a safe remove.
I don't think they'd care that anyone could detect them if they're that advanced...
TO avoid detection by some other warlike species?
Regardless of the alienness of a life form, there are certain principles one can rely on, under average circumstances:
* Resource aren't infinite anywhere, and an intelligent species won't deliberately waste resources.
* No civilization is invulnerable.
* The duration of existence of any lifeform is finite.
There will always be outliers, but if we're after a set of reliable assumptions, these are on the list.
> I don't think they'd care that anyone could detect them if they're that advanced...
If you wrap a star in collection surfaces, thermodynamics dictates that the result will be a much larger surface at a lower temperature. If that isn't true, then the point of the exercise (energy collection) won't pan out.
Obviously this is rank speculation, but knowing what we do about living species, some speculations are more likely than others.
The next most likely is probably relativistic projectiles, which are dangerous in proportion to the energy required to send them (i.e., they aren't that likely a threat).
Direct invasions of civilizations that can shape the matter of an entire solar system seem pretty much destined to failure (I guess you could come in on a ship built from an entire solar system, but I wonder if you are war mongering at that point).
Because they might attract the attention of greater beings.
As a life form we don't seem to be taking any precautions to 'hide' from others.
Why are assuming others would like to 'hide'?
What's an "energy alternative" ?
Your parent comment implies they would have an "energy alternative" to... energy.
When you say "A civilization so advanced as to be able to capture the entire energy of a star, probably also has energy alternatives".
What "energy alternatives" are you talking about?
No, not at all. A walking alternative is bicycling, not being a double amputee. A coffee alternative is tea, not dehydration.
"Energy Alternatives":
http://www.energyalternative.com/home.html
Wikipedia: Alternative Energy:
http://en.wikipedia.org/wiki/Alternative_energy
A quote: "Alternative energy is an umbrella term that refers to any source of usable energy intended to replace fuel sources without the undesired consequences of the replaced fuels."
"The energy alternative":
http://www.theenergyalternative.com/
"Alternative Energy News":
http://www.alternative-energy-news.info/
> What "energy alternatives" are you talking about?
Want more links?
(My understanding is that solar is the alternative to things like coal)