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Comment by jandrese | Hacker News Reader

It doesn't help that we have a giant noise source in the middle of our solar system that shoots the noise floor through the roof when you're trying to detect laser comms over light years.

Plus, even at lightspeed you're talking multi-year roundtrips to our nearest interstellar neighbors.

Our entire history of radio emissions has only made it to around 500 solar systems currently. Even if someone was listening and responded immediately the response probably wouldn't have made it back to Earth yet.

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> Plus, even at lightspeed you're talking multi-year roundtrips to our nearest interstellar neighbors.

That's something I think people ignore. It takes 4 years to get to the next closest star at the fastest possible speed.

And that's ignoring all of the other issues with long term space travel. 4 years. To a place where we're relatively certain doesn't have life capable of technology.

The assumption that other intelligent life will conveniently find a way around the speed of light is a big one.

You're completely ignoring the time dilation effects of relativity. From the perspective of a fast moving spaceship, the distance between stars contracts, and from the perspective of an outside observer, the time experienced in the spaceship slows down. This is why I believe that interstellar travel will be feasible, although creating any sort of empire will be impossible. Here's a quote from the Wikipedia article on time dilation:

"Theoretically, time dilation would make it possible for passengers in a fast-moving vehicle to advance further into the future in a short period of their own time. For sufficiently high speeds, the effect is dramatic.[2] For example, one year of travel might correspond to ten years on Earth. Indeed, a constant 1 g acceleration would permit humans to travel through the entire known Universe in one human lifetime.[12] Space travelers could then return to Earth billions of years in the future. A scenario based on this idea was presented in the novel Planet of the Apes by Pierre Boulle, and the Orion Project has been an attempt toward this idea."

https://en.wikipedia.org/wiki/Time_dilation#Velocity_time_di...

Constant 1 G acceleration requires three things:

1. An infinite power source

2. A reactionless drive

3. A spacecraft made of material so strong that it can survive collisions with rocky material at velocities very close to c. Or a Star Trek style deflector shield.

Warp drive is probably easier to achieve.

Detonating nukes behind your spaceship will never give you anything close to 1G constant acceleration over a long period of time.

Time dilation has some definite drawbacks as well. Say for example you have a very redundant ship that can repair damage from micrometeorite attacks in a few minutes. The hits are very rare, maybe once a year at most at normal velocity. But now you're traveling at a high fraction of C and you're hitting tens of fragments per second, and always at a high fraction of C. Your repair process is effectively working in slow motion and could very easily get overwhelmed. Without a sci-fi energy shield your spacecraft is ablated to death long before you get anywhere.

> multi-year roundtrips to our nearest interstellar neighbors.

At lightspeed it's an instantaneous trip to the traveler. It's only a multi-year trip to those who are still on Earth.

That comment was in reference to communicating with the star system. Nobody is traveling in that case.

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