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Old Wolf's avatar

I enjoyed reading this immensely. You think about a lot of things I've also thought and written about on here. I'm no scientist, just another curious person, so don't take anything I say as authoritative.

With that being said, there are a few things you might want to bear in mind. First of all, there's the factor of time and relativity (speed of light and all that). Even when we look at our "local" neighborhood outside of the Solar System, the light we see is years old. The three stars of Alpha Centauri (plus the one planet our astronomers have been able to confirm is over there) are about 4 light-years away. Proxima Centauri, the closest of the three where that little planet is, is about 3.5, but still... the light has to travel years to get here even from there. What we're actually seeing is what those stars looked like 4 years ago.

Now you've got to extend that logic outward. The Milky Way is about 100,000 light-years across. That doesn't mean any space wars that have happened in the last 100,000 years would automatically be visible, either. We'd have to be looking at the right time to catch the light from a death star blowing something up, or to see some alien civilization building a Dyson sphere to enclose a star. Granted, the second would probably be visible for much longer than the first, as you'd see the star gradually dim until the swarm or shell was completed and it finally winked out... but that's *still* not all that long in the grand scheme of things. You'd have to be looking up at the right time, or have technology in operation to monitor the sky at the right time to catch it. Same difference.

Now for the second big factor: visibility. Don't assume that just because astronomers have used radio waves and various things besides visible light to calculate the size of the Milky Way that we can see the whole thing from here. That's not true at all. There are nebulae (giant dust clouds in space) scattered all over the galaxy, and they obscure little bits of it here and there... but the big thing a lot of us non-astronomers don't really think about is the galactic center. There's a giant black hole there called Sagittarius A, and it's so huge that the whole galaxy orbits around it like the planets here orbit our sun. There's a lot of dust near that thing too... so much of it that the astronomers of this world can't see a dang thing on the other side of it. This means there's a pretty big portion of the Milky Way that isn't visible at all until and unless something gets sent there to look at it, just like no human being in history had seen the "dark" side of the moon until astronauts went up there and took pictures of it.

Also, back to the time factor for a moment... we humans invented the radio a little over a hundred years ago. Radio waves travel at the same speed as visible light, so that means there's been enough time for our radio waves to spread out over a sphere of about a hundred light-years around our world. That also means that any aliens out there who use radio waves to communicate are bound by the same rules, and if they started broadcasting 50,000 years ago but live 100,000 light-years away we still won't be hearing from them for a long time. Also, radio waves do dissipate and decay over time. There's no guarantee any alien transmission would be recognizable by the time it reached us... assuming that's what they use. In all honesty, if there is anything better than radio waves and advanced aliens are using that to talk to each other across the stars, we probably don't even have the tech to open the chat window yet, much less add a comment of our own.

There's a whole series about this on YouTube. Based on the thoughts you shared here, I highly recommend it.

https://youtube.com/playlist?list=PL6omQ6_kiTietmvmzzF85iTrY_7bXpnlA&si=CpDq1-6CDGJ1ziB0

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