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Comment by sevenless | Hacker News Reader

The thing is that subjectively "FTL" travel, a la Star Trek, is totally possible thanks to special relativity contracting distances between objects.

A little math shows the relative velocity in which you travel one light year measured in a rest frame, in one year in your spaceship's frame, is 70.7% of the speed of light.

If you happened to be moving at the ludicrous speed of the "Oh-My-God" cosmic ray recorded in 1991, it would take you three seconds of your time to travel to the center of the galaxy.

That should be good enough for anyone!

https://www.fourmilab.ch/documents/OhMyGodParticle/

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The center of the galaxy is 32,000 light years away. 32,000 years will have passed at the center of the galaxy by the time you get there in your 3.2 second journey. If you then turn around and go back, another 32,000 years will have passed before you get home.

It might feel more like time travel than space travel.

That's why it's called space-time right...

This is one of my theories about why there isn't any alien life around. There is some party far in the future with a beacon or message that shouts "JOIN US HERE IN THE MIDDLE OF GALAXY R345Q2 10 BILLION YEARS IN THE FUTURE!"

After about 10 thousand years of hearing the beacon and being alone we finally get restless and just build a couple thousand giant spaceships and join the rest of the universe in the most cosmopolitan place ever.

It's not a party, it's a restaurant :)

> This is one of my theories about why there isn't any alien life around.

Do we need a theory on this yet? I mean... out of all the planets we've explored reasonably thoroughly so far, 100% have had life at some point.

I've not heard that Mars had life at some point in its history. In fact I've not heard mention of any planets hosting life in their past, do you have some sources that you can point me to?

It's about the definition of 'reasonably thoroughly'. We haven't explored much of Mars, having covered only single digit square kilometers up close (and most of that geologically).

Uh, yeah? Von Neumann machines should be everywhere by now; yet there is no evidence of them.

Life yes. Intelligent life, no.

Intelligence might not even bet he end goal of evolution even life is very common, intelligence might not be.

Huh, this is a really fun thought experiment. Does anyone know any scifi books that explores this (or a similar) concept?

As vslira alluded: https://en.wikipedia.org/wiki/The_Restaurant_at_the_End_of_t...

Oh, I've read that five part 'trilogy' several times :) I guess I should have said...

Douglas Adams' books have been a major fixture of my life since I was 12. He really was ahead of his time. Actually I don't think said time he was metaphorically ahead of has come yet :)

https://en.wikipedia.org/wiki/The_Restaurant_at_the_End_of_t...

"A Fire Upon the Deep" explores a related concept.

What I've always found interesting (not sure if there's a name for this) is kind of the idea that if you made such a trip, you might find by the time you arrive there in 3.2 seconds, the rest of humanity has figured out true FTL travel with the technology that was developed during those 32,000 years. As a result, you arrive in what might be the equivalent of a horse and buggy at the center of the galaxy versus what everyone else is riding around in.

There was an Episode in Andromeda that dealt with that same thing.

There was also an point in that episode since the FTL method they used was tethered to massive objects and hence only allowed for travel from on star system to another (or from one galaxy to another) the old fashioned non FTL method allowed them to explore many more things than with FTL travel the downside that 10,000's years would pass for everyone else every time they take a trip.

Lots of science fiction stories have this concept, but usually they talk about Slower-than-light, multi-generational space ships that takes centuries to reach the next star, only to find that during the last 100+ years, the destination planet has already been settled by humanity.

The wealthiest leave early thinking they might be getting the best and the first.

Poorer people leaving later get better and faster transit.

The only advantage of leaving early is the guarantee of getting a transit, instead of waiting for a better one to arrive later and find you got nothing at all.

But length contraction means that, subjectively, you'll think you've only travelled a few hundred thousand kilometers.

This explains the famous line from Star Wars about the Millennium Falcon "making the Kessel run in less than 12 parsecs". George Lucas was obviously hip to the implications of special relativity.

I think the retconed explanation is that the kessel run involves going around a black hole. Bragging about parsecs is because the slower ships had to completely steer free of the blackhole, while faster ones could get closer and break free of it's gravity, thus shortening the overall distance traveled.

I prefer the explanation that Han Solo thought they were total rubes, and gave them some nonsense just to impress them.

Indeed, the fourth draft of the script has this comment after the "twelve parsecs" line: "Ben reacts to Solo's stupid attempt to impress them with obvious misinformation." The final draft says he's "obviously lying."

I feel like this ridiculous retcon involving black holes, rather than sticking to the simple human explanation of braggadocio, is a microcosm of everything that subsequently went wrong with the prequels.

After seeing Interstellar and some Black Science Man explanations this would also mean that the fastest ships would get to the finish decades after the slow ones due to gravity shenanigans.

Still gonna need some inertial dampers though.

That bit about the particle is fascinating, but I am struggling to understand why a particle that travels at 0.99x of the speed of light is faster than a ship that travels at 1516x the speed of light. Is the Star Trek universe not subject to time dilation?

The star trek universe is not subject to physics in general. Sound traveling without air, time travel, FTL, Newton's Law being ignored, Creating/destroying matter, "beaming" people down to a planet, etc.

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