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Comment by gorgoiler | Hacker News Reader

Our galaxy is huge but we don’t really notice because it is so bright, and moreover has been bright for a very long time.

The light we see is old. It’s of interest for studying the science of bright old things but for anything contemporary it is useless. If you ignore our own star and count out the ancient starlight, the sky is completely dark to us.

It is as if we are searching for someone to talk to by rummaging through rocks, looking for fossils. It applies to humans too. Anyone we sent to another star would be gone for years. They would be physically gone, but fundamentally we just wouldn’t be able to talk to them at all for years on end.

Unless something about the speed of light changes, Earth and her inhabitants will always be completely and fundamentally alone.

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Our galaxy is "only" 50,000 lightyears across. 50k years is an eyeblink in cosmological terms. Behaviourally modern humans have been around about that long and it's too short a time for fossils to even form, except in extraordinary conditions. It's a thousandth of the time to the dinosaurs. I think that's reasonably up to date in evolutionary terms.

Andromeda at 2.5m ly is a bit more of a stretch, but it's still a fairly short period in the history of life on Earth. It all depends on how long we think technological civilizations last on average. If they can reach sustainability it could be at least as long as their solar systems remains habitable, maybe hundreds of millions of years, even without interstellar travel.

"The light we see is old. It’s of interest for studying the science of bright old things but for anything contemporary it is useless. If you ignore our own star and count out the ancient starlight, the sky is completely dark to us."

Even sunlight is really old.

The photons from our own star, the sun, were produced 100,000 years ago. That's how long they take to make their way to the surface from center of the sun where the nuclear fusion occurs.

True, but then it's just 8 minutes from the sun's surface to the earth's.

You mean the energy from the core of the sun took 100k years to reach the surface and be emitted as photons.

Gotta disagree on that one. Well maybe with the small change to "Earth and her current inhabitants".

There's current projects that hope to launch small probes to the nearest start (under 5 light years away) at a few % of speed of light powered by large arrays of lasers. Assuming it gets attention and additional funding the probes will get bigger and of course sensors are continuing to improve per unit of mass.

With a better survey of the nearest star, plants, asteroids, comets, and magnetic field we'd have a much better idea for what to send next.

Assuming reasonable progress on fission, fusion, plasma drives, light sails, and related technologies we could look at accelerating on this ends and slowing down at the opposite end. Once we can send small probes they would work on building mirrors to help decelerate whatever we send next. Similarly on this end we could put more solar panels+lasers in orbit to help with launches.

If any of the planets looking promising it doesn't seem insurmountable to eventually send humans (or at least their DNA) to the nearest star.

With some form of hybernation or life extension Milky Way could be open for exploration even without ftl travel.

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