Even with extended life span ain't nobody ever going to another galaxy.

Even if we could travel at the speed of light, it would take 2.5 million years just to get to the nearest galaxy.

If we could travel appreciably close to the speed of light, the journey could be close to instantaneous for the traveler. (Depending obviously on how close to light speed we’re talking about.)

Time dilation is a nice property.

Indeed - something often misunderstood as always recorded from the perspective of a third party observer.

Quick follow up question. If you did depart and travelled at near-ligth speed to another galaxy, arrived there in a few seconds and then looked back at the earth - would it appear as only a few seconds have passed for the earthlings back home as well?

By the same token, if you are actively watching another galaxy as you travel at near-light speed towards it - will you be watching that galaxy "age" at an extremely fast pace throughout the journey?

I think the downside is that for earth, time is passing by at 'normal' speed. So as soon as you get up to speed you're leaving behind, possibly the entire human race.

Weird to think that too if aliens show up. Their entire civilisation is probably already gone (unless it's VERY stable over hundreds of thousands of years).

that's an interesting question.

If you traveled one light year at the speed of light, when you looked back you would see light from right after you left. But since you were traveling at the speed of light, your relativistic time for the journey would be zero.

So the light you observed would be proportional to your subjective time.

So, by the same token, do you observe the galaxy you're approaching age quickly? On "fast-forward" if one could imagine that?

It might make more sense to take off in your near-light-speed ship, do a few laps of the galaxy, then return home for a thousand-years-in-the-future ship upgrade, then head on to another galaxy.

There has to be a hack.

Wormholes, maybe?