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Comment by 5350-uiop-1130 | Hacker News Reader

>something like 18 000 years

this is why we don't see any signs of life out there. there really isn't any point in trying to venture beyond your home. universe is just too big even at the speed of light when you start venturing beyond your local group.

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That is assuming that the speed of light truly is the end-all-be-all. It is quite possible there are other ways of travel that we’ve yet to discover. I have no idea what they’d be but humans have really only been doing this space / astronomy thing for a few hundred years at most.

We have barely scratched the surface of what is truly going on out there. It would be incredibly “human centric” to think our current understanding of the universe is “it”, in my opinion.

I think you would need a kind of power that would have obvious hallmarks, like literally rewriting the rules that underlie the universe. But's that just my cynical perspective.

I guess that's why arthur c clarke said sufficiently advanced technology is indistinguishable from magic. I just think that kind of magic would be visible to us. Or maybe it is, but we just can't tell.

> even at the speed of light

If you get really close to the speed of light (which is not really practical from a materials engineering standpoint) your time of transit is significantly shorter.

Once these (extremely hard) engineering problems are solved, a trip to the next star can be a week-long affair from your point of view, but your friends back on Earth won't see you for about a decade.

You'd have to get very close to the speed of light, before you'd see any really significant relativistic effects.

That just isn't practically doable with any technology within humanity's reach, probably for centuries. If it ever will be at all.

The amount of energy needed to propel anything at that speed is enormous.

Unless my math is very wrong, at 0.9c the passenger perceived time is more or less half the perceived time from the departure point. That's already quite significant, although not something I could do over a vacation ;-)

In order to spend a leisurely "cruise-ship" week to Proxima you'd need to go very close to c. At that speed, even friction with a non-ideal vacuum is a problem :-D.

> a trip to the next star can be a week-long affair from your point of view

You’d need to travel at around 233x the speed of light to make getting to the nearest star be a week trip, no?

The effect is called time dilation. The section of interest here is „Time dilation caused by a relative velocity“:

https://en.m.wikipedia.org/wiki/Time_dilation

I’m aware of time dilation, my point was that a “week vacation” to something “over 4 light years” away is just hyperbolic.

Nope! If you obtain the full speed of light then a) you're not made of baryons anymore so congratulations on that and b) no time passes whatsoever between your being emitted in some tight laser beam on planet A, and being transcribed on planet B, from your perspective.

None. Photons don't experience time, they are time.

Not exactly. For you to think you are traveling 20x faster than light, your friends that stayed at home would have to see you traveling at 0.99995c. For 233x faster than light, that's a lot of 9's in that number.

I get 0.999c for 20x and 0.99999c for 220+

I'll trust your numbers more than mine.

But, for all intents and purposes, this is impossibly fast ;-)

Unless you are on the Bistromath, that is.

There is no faster than light, I can't parse this statement.

Distance divided by [time experienced by traveler]. GP is not saying that traveler went faster than light.

From the passenger's point of view, yes. For everyone else you'd be veeeery close to c, but not quite there.

My point was it’s hyperbolic. You’d have to be going so close[0] to C that it’d be impossible.

[0] about 0.99999c if what someone else in this thread said is correct

I guess the assumption is their life span is similar to that on our planet. If the life span measured in thousand of years, it will be a different story.

Lifespan is one thing, but also the "cadence" of life. For a mammal, spending a year in a spaceship is hard. For a brick, spending a thousand years as part of a wall is the natural order of things.

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