Other civilisations in the Galaxy - are they really that likely?

I don't think there would be any impossibility with it and it would definitly be the mark of an advanced society.
Some have even said that an advanced society may use tiny time-dilated wormholes around the universe in order to probe areas they can't afford to contact n person. Not so much that its possible, it just gives you an idea of what an advanced society might be able to do.

I did thanks. I think it is a good example of why Occam's Razor is inapplicable in such situations (i.e. no communication implies no communicators). When you have very few facts, OR is not very helpful as it is difficult to define "more simple". I think this is equally true in trying to reason the non-existence (or existence in some cases) of God via OR.Back to your question of using grav waves - certainly possible except that the transmitters would have to be a little on the big side. A pair of neutron stars would serve for a small transmitter, but modulating galactic collisions would be preferable for large scale transmissions. Of course, you are still restricted to speed-of-light communication.

Hey,All equations and ions aside, let's look at civilization as an adaptive trait formed by one species as a succesfull method of interacting with the environment to promote it's genes. It is an adaptation (or rather, series of adaptations) that require very specific cost:benefit ratios to succeed, as much as the bill of a Platypus or the legs of a Flamigo.Should life exist anywhere else in the universe, it must also adapt the same way as ours did (barring all other possibilities). When the question is phrased this way, the possibility becames even more remote. You're no longer asking for a prediction from an equation, you're asking for a universal coincidence.—
Theus

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Veri Omni Veritas

well, not all creatures on this planet have adapted civilizations, although it could be said that most have some to some degree. what's to say that an adaptation MUST evolve?(btw you spelled "shalom" wrong)

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אָרַח

Good point, there is no reason that a given adapation should evolve, or even be the only method around a bend in the reproductive success curve. However, it does emphasize the uniqeness of our current humanity (not to say other organisms aren't either). But the evolution of social behavior doesn't quite indicate civilization, the latter assumes technology and beaurocracy.Au revoir,
Theus

That would be one problem certainly -- from our current perspective eh?What other waves\systems could be used? Perhaps something from spooky action?

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RebelAAmerican.Zen[Deist
... to learn ... to think ... to live ... to laugh ...
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interesting concept -- {civilization\culture\society} as a behavior mode that extends beyond {group} interactions. good for a new topic?

Aren't wormholes tied to string theories?

Intended pun?No, not really. Wormholes appear as solutions in GR. They just require effective negative energy densities to support the "throat". We see this kind of energy density in the Casimir effect and in your beloved dark energy So for a wormhole you just need GR and a bit of QM/QFT to supply the -ve energy. Of course, string theory is a good place to get both at once...

Absolutely, though I guess if we can solve that one, we won't be stopping to think of grav wave transmitters as we will have anti-grav, artificial grav, and inertial dampers to play with. We won't be transmitting... we'll be going... Spooky action is probably not the right route... it's a bit like all of the "faster than light" revelations that are always down to group velocity. It's just a naive misunderstanding.Other waves...well, we already use the best: e/m. We are just too spoilt with it that we don't appreciate it enough. It's a remarkable fact of the universe that the photon exists (an abelian gauge particle) because (and I keep saying this) without it there would be no sight... probably not much else either!

yes, I don't think there will be faster than SL communications, but maybe some way of riding an interference\connection .... yes, but there is also a lot of interference on the bands ... some other system may not be so cluttered so long distance \ low power can still be received. I'm ready

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RebelAAmerican.Zen[Deist
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Oh, I see what you mean. Yes, something associated with this is certainly plausible. However... Don't forget that EM is not just "radio waves". It is laser, quantum interference, etc, etc. Photons are ubiquitous, long range, and they don't interfere with each other. Even with radio waves, it doesn't matter how much interference there is, the original signal photons are still there to be extracted given sufficient technology. When the photons are in the form of coherent light (lasers) then it is much easier. And "long range" quantum experiments almost all use photons.On the fermionic side, neutrinos suffer almost no interefence and so are very long range, but becasue of this they are also virtually impossible to detect. The usual recipe to catch a particular neutrino is to block its path with a planet sized lump of lead... you've then got a 50% chance of stopping it!Gravity waves are long range but there is a problem that they are non-linear so there is no superposition (in the classical sense). In other words, theoretically, two overlapping gravity waves cannot be separated into the two original signals (something we appallingly take for granted every second with our hearing, where we separate out God knows how many separate sounds from a single compression wave). Practically, gravity waves are so weak that they are approximately linear and so this should not be a problem.The other known massless and hence potentially long-range field, thestrong force, is useless because of colour charge confinement of the gluons.Now there are the theoretical scalar fields: the inflationary driver, dark energy, the string theory dilaton, etc. These are possibilities but manipulating these fields is pretty much in the same league as manipulating gravity. Good, but of course we do not need any super advanced technology to go to the stars. That is where the physics in your story goes astray (as it does in the majority of sci-fi). We can collonise the entire galaxy in our (the collonists) lifetime, simply taking advantage of time-dilation. Of course thousands of earth years will pass by, but if the whole point is to diversify mankind across the universe, then what is the problem? Far far better than sending boring robots, who will take just as long to do the job.

Thanks. One of the reasons would be to have some eggs in different baskets. We know that an astronomically improbable event 'took out' the dinosaurs, so if we are concerned with the long term survival of the human species (and necessary earth life) then we need to look at off-planet solutions, and ultimately out-of-solar-system solutions.

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RebelAAmerican.Zen[Deist
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Of course. It's a simple case of risk management. On a sufficiently long time-scale, nowhere is safe. So diversification off-planet, extra-solar, extra-neighbourhood, extra-galactic, extra-cluster, and eventually we may just have to jump universe... or create our own

Not picking snits here, but given the time scale involved how "improbable" was the meteor hit? Seems like if you take an sufficiently long period of Earth's history, you'll find a significant impact of one kind or another.I'd say the next one is eventually inevitable.