Holy Smokes! The aliens would have to have very good aim to hit earth with a laser from light years away. You thought the US hitting a satellite with a missile was incredible? That would be child's play compared to trying to hit our tiny planet with a laser, repeatedly. They would have a hard time hitting our solar system repeatedly. Here is why:
Our entire galaxy is in motion. Everything in the galaxy is in motion and not all of the motion is directly relative to the other. The solar system is moving through our galaxy's arm. The arm of our galaxy (all the stars and stuff) are moving around our galaxy. Our earth is moving around our sun. AND all of this has to be timed so that the laser light has to be fired to where we will be when it gets to us in several light years (10 to 100?).
This is one of the reasons that communication and visitation between interstellar beings is unlikely.... space and time are a killer for neighbors. By the time one race realizes that another race could exist in another part of the galaxy, the information might be thousands of years old. It would take us a few thousand years to reach out to them (at light speed) with any sort of communique. We would have to calculate the communication shot to get to them a thousand years in the future.
By the time any species got around to visiting the other, one or both could likely be exinct. We have only been capable of interstellar communication (extremely limited) since about the 60s (40 years). We have only existed as intellectuals for about 10K years (and that's debatable).
If it takes us 2 thousand years to exchange an idea with an alien species, unless we figure out how to bend space (warp), there could be hundreds of thousands of other intelligent beings out there and we'll never be close enough to talk or visit before one race or the other or both no longer exist (say over hundreds of thousands or even millions of years in earth time).
“If it takes us 2 thousand years to exchange an idea with an alien species, unless we figure out how to bend space (warp), there could be hundreds of thousands of other intelligent beings out there and we’ll never be close enough to talk or visit before one race or the other or both no longer exist (say over hundreds of thousands or even millions of years in earth time).”
Of course that’s just as likely as anything else. On the other hand, they could have 50,000 year natural lifespans or have beaten natural death completely and plan their projects by million year periods.
Freegards
very well put. i was thinking the same thing but you explained it a lot smoother than i could.
Physics was never my strong suit, but at “light speed” wouldn’t communication be instant? (for the message or person doing the light speed traveling).
Not sure how it would translate to a target that was many light years away but, " the "pencil beam" directly generated by a common helium-neon laser would spread out to a size of perhaps 500 kilometers when shone on the Moon (from the distance of the earth)" [Wiki]. So, hitting a solar system that was 40 light years away, say, might not be that much of a problem for an advanced civilization. But all your points are pretty good ones. It wouldn't be a piece of cake, when everything is taken into account, that's for sure! Personally, I don't believe this "new" approach is going to have any more success than the others because if advanced civilizations weren't extremely rare and extremely spread out in both space and time, we would have heard from them by now, imho.
I was going to say something but you beat me to it.
Well said.
What’s the propagation time for gravity?