Re:Alone in a Crowded Milky Way
by hnuser123456 on Thursday January 02, 2020 @03:48AM
(#21933861)
>Vega (~26 LY away, furthest star anyone on Earth could visit and then return from in a lifetime)
It is not necessarily true that more time is spent aboard a ship than light would spend taking the same path, as measured by an external observer.
If you had a ship capable of accelerating at 1g indefinitely, then as measured by the crew, they could cross the galaxy in only 24 years.
https://en.wikipedia.org/wiki/Space_travel_using_constant_ac...
To an observer who is self-propelled (and has enough energy), the speed of light (as seen by others) is no limit. It's not like you can fire your thrusters and NOT gain momentum and speed; or that, as you accelerate, the stars start passing by at the speed of light, and suddenly your ship jerks, ceasing to accelerate, because you hit an invisible velocity brick wall.
Yes, relativistically, you can travel anywhere in the Universe and only have seconds pass for your frame of reference. But I thought that Vega was the furthest star that you could travel to and from and then still have people you knew here on Earth that were alive. Also, I was totally wrong about Vega. I think that was my reading of Contact that gave me the thought. There are a LOT of systems that are inside of 30 LY from the Sun: https://en.wikipedia.org/wiki/List_of_star_systems_within_25...
Re:Alone in a Crowded Milky Way
by ByThyGrace on Wednesday January 01, 2020 @09:29PM
(#21932494)
I wish I could save comments so I'm just replying instead. It is so fascinating.
Bookmark the time stamp
To image something like the roadster on a Planet orbiting Vega (~26 LY away, furthest star anyone on Earth could visit and then return from in a lifetime) you're looking at lenses greater than the orbit of Pluto, ish.
Optics/Physics is a bitch here. To really see/prove there are aliens running about, they have to screaming at the top of their lungs for a very very long time, hoping against hope that anyone will hear. It's just really really hard to build equipment that can passively listen for accidental broadcasts and spy on alien cars. At least under our current understanding of physics.
[0] http://hosting.astro.cornell.edu/academics/courses/astro201/...