One of the neat things that I've stumbled across is https://thinkzone.wlonk.com/SS/SolarSystemModel.php

Make the model scale to be 10000000 (10 million). The sun is a chunky 139 meters in diameter. Earth is 15 km (9 miles) away. Pluto is 587 km (365 miles) away. The speed of light is 107 kph (67 mph).

Alpha Centauri is 4.1 million km (2.5 million miles) away... that is 10 times the earth moon distance.

Another comparison... Voyager 1 is moving at 30 light minutes per year. (Andromeda galaxy is approaching the Milky Way at 3.2 light hours per year)

Less than that is you are constantly accelerating.

If you can figure out a way to apply thrust that doesn't require you to lug mass with you and throw it out the back of your spacecraft you will open up the stars to exploration. If not the rocket equation will wreck your plans every time.

Why?

75k years in geological timescales is nothing.

If there are creatures who could live longer than that, perhaps by hibernating or just having really long lifetimes, space exploration is feasible with slow craft.

75k years of reliable operation for complex machines operating in a hostile environment is a different story. This includes organic life. You can't just bottle everything up and wake up thousands of years in the future, you will be under constant bombardment by high energy particles, micrometeorites, and the relentless cold vacuum of space with no access to new raw material or energy for almost the entire trip.

If you can make that kind of trip the question becomes why bother? You could have used the same technology (actually a much easier version of the tech since you will have access to external resources and don't need to attach enormous engines to get it moving and then stopping at the destination) to use the almost unlimited space in your home solar system instead.

Unless your sun is literally about to explode it is hard to make the argument for the incredibly difficult and long journey to a neighboring solar system.

Yea, why did humanity ever bother leaving Africa? They had everything they needed.

>If you can figure out a way to apply thrust that doesn't require you to lug mass with you and throw it out the back of your spacecraft you will open up the stars to exploration

This is also called "Everything we know about physics is so radically wrong that it shouldn't be possible for us to make the predictions we do"

Reactionless drives are not physical, or if they are physically possible, will have such unique quirks and constraints as to be meaningless outside of some insane laboratory setup.

For example, making very high weight new atoms that have never existed in the universe before is physically possible, but the realities of making those atoms and their nuclear instability means it doesn't matter even if a super heavy element has some crazy properties that we would like to exploit, because there will never be enough of that element to make anything out of. The "rules" of atoms should still work well above 180 protons, but other physics makes that meaningless.

Without reactionless drives, interstellar travel is so physically difficult to be essentially impossible, and no amount of engineering or cleverness can change that.

Longer than that if you are constantly decelerating.

And exactly that if you're talking about Voyager 1, which is on a ballistic trajectory.

Less than that if you're going faster too. What's your point?

I believe there's a semi-common sci-fi construct to send probes containing human brain dumps running on silicon to these far away star systems. Just hit pause until a week before arrival :).

At Voyager 1's velocity, it would take ~456 million years to reach the heart of the Milky Way (Sagittarius A*), some ~26,000 light-years away. That's roughly the same amount of time that has passed since the Ordovician–Silurian extinction, when volcanic eruptions released enough carbon dioxide to heat up the planet and deoxygenate the oceans, resulting in the asphyxiation of aquatic species (about 85% of all life was snuffed out). The oceans remained deoxygenated for more than three million years.