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wetterbread t1_ja3lve8 wrote

We can see their past. But never their present.


Pineapple_Incident17 OP t1_ja3m0lc wrote

Exactly. So if there’s someone out there looking at us, wouldn’t they also be seeing our distant past?


Anonymous-USA t1_ja3my6e wrote

Yes… and “seeing” may come in different forms, from spectral analysis to microwave to radio wave transmissions. Bare in mind that those radio waves may have red shifted into the microwave frequencies (SETI may have been looking in the wrong place).

On the remote chance we do detect an alien signature, the source of it will probably be so far in the past that that civilization will probably also be extinct. And certainly too far away for us to communicate with it.


triffid_hunter t1_ja3myig wrote

We could barely see evidence of our own existence with current tech from more than a few dozen light years away - and the most obvious evidence for sapient life here that's distantly visible is the radical change in atmospheric composition over the past hundred years or so, which is only visible (with our tech) from locations that lie exactly on our equatorial plane such that Earth passes between those locations and our sun every year.

In terms of radio transmissions, we're struggling to communicate with the Voyager craft and they've only just passed the heliopause…

We'd never detect alien tv/radio transmissions even from the nearest stars, and that's assuming that we're even listening at the right time to catch the narrow high-power transmission window - terrestrial communications have invested hard into more efficient methods as well as widespread encryption, meaning that 1) there's dramatically less RF blasted into space compared to 50 years ago, and 2) what is broadcast is essentially meaningless noise.


BitterDropToSwallow t1_ja3nzdm wrote

Exactly..and this is what baffles me of people who defend the Fermi Paradox and swear aliens don't or can't exist because we've never seen them. IT's such a mind boggingly large, vast universe, I'd be more stunned and flabberghasted that we did see evidence so quicly.


weathercat4 t1_ja3nly8 wrote

I don't think you are truly appreciateing the extreme depth and scale of the universe.

There are hundreds of billions to trillions of galaxies in the observable universe to distances of billions of lightyears.

Consider this, civilizations on the other side of the milkyway wouldn't be able to see us yet. Out of potentially trillions of galaxies, just as you said they could see our galaxy but would have to wait millions to billions of years before they could see our civilization.


Pineapple_Incident17 OP t1_ja3peqk wrote

Wow, you’re absolutely right, I hadn’t considered that. I sometimes feel like I’ve got a good grasp on the scale of things, and then realize my perspective is still incredibly skewed. Thanks for your insight!


space-ModTeam t1_ja3nkau wrote

Hello u/Pineapple_Incident17, your submission "If what we observe from other galaxies is light that’s millions of years old, is it possible there are other life forms in those galaxies and we just can’t “see” the evidence of their existence?" has been removed from r/space because:

  • Such questions should be asked in the "All space questions" thread stickied at the top of the sub.

Please read the rules in the sidebar and check r/space for duplicate submissions before posting. If you have any questions about this removal please message the r/space moderators. Thank you.