[lutusp]

Let's be realistic. A civilization so advanced as to be able to capture the entire energy of a star, probably also has energy alternatives, and probably wouldn't want to attract the attention of lesser beings (like us) by trapping a star's output in a detectable way.

[enraged_camel]

I've never understood such assumptions of intelligence. "If a civilization could do X, they could also do Y and Z." Says who? It's not like we're experts in alien intelligence. How can we be, when we have never encountered one?

[lutusp]

All true, but applying common sense still has a point. For example, do we want to broadcast the fact of our own existence across interstellar distances? This is actually an active debate topic among those who think about stuff like this.

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.

[kamaal]

>>do we want to broadcast the fact of our own existence across interstellar distances?

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.

[lutusp]

> We are already doing it ...

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.

[jakeonthemove]

Sure, they could have their own nuclear fusion reactors or even something more sophisticated, but why let a perfectly good source of energy just go to waste?

I don't think they'd care that anyone could detect them if they're that advanced...

[lutusp]

> Sure, they could have their own nuclear fusion reactors or even something more sophisticated, but why let a perfectly good source of energy just go to waste?

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.

[maxerickson]

The most likely shape of interstellar war is lasergrams that say "We hate you" (but here is some harvestable energy...).

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).

[aplusbi]

Why wouldn't they want to attract the attention of lesser beings?

[lutusp]

> Why wouldn't they want to attract the attention of lesser beings?

Because they might attract the attention of greater beings.

[kamaal]

>>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'?

[Haplo]

It could very well be that the only civilizations that still exist are the ones that are good at hiding. All the others (even if they are the big majority) might have been destroyed after giving a signal of life/existence.

[strait]

Greater beings are nothing to worry about. They remain undetectable in order to preserve the lesser beings as long as possible.

[strait]

I'm guessing that it's not unlike why we don't leave food out when camping in bear country. If the bear realized what we were doing (hiding food from it), then it would surely come to the bear conclusion that our behavior was unreasonable, but we know better.

[apedley]

I agree. From my limited knowledge of power sources, I understand that fusion and zero point energy would provide more easily accessible and vaster amounts of energy than one could build with a huge solar collector. Solar can only go to the maximum that the sun outputs in that direction. I would speculate that alien civilizations have found far more efficient means of power than a solar array.

[gibybo]

It wouldn't just be one direction, it would be a sphere around the whole star. Stars are essentially just large fusion reactors, so it would take one the size of the star to compete with it (within an order of magnitude or so).

[grecy]

> also has energy alternatives

What's an "energy alternative" ?

[lutusp]

Fusion is an energy alternative to coal. Wind is an energy alternative to solar, and vice versa. Things like that.

[grecy]

Right. I get that.

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?

[lutusp]

> Your parent comment implies they would have an "energy alternative" to... energy.

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?

[grecy]

Interestingly, you're talking about an energy alternative to solar. Do you have an example of one of those?

(My understanding is that solar is the alternative to things like coal)