Make sure you press the "c" button in the bottom right.
Light is incredibly slow, and everything seems out of reach.
I think we'll have a holodeck before we reach another star. And maybe that'll be enough.
Light is incredibly slow, and everything seems out of reach.
I think we'll have a holodeck before we reach another star. And maybe that'll be enough.
From the hypothetical perspective of a star, with a lifespan measured in billions upon billions of years, the entire ecoscape of the world changes in a blink. From the sun's perspective, MENA was green just a very short while ago. Hell, Pangea wasn't that long ago. At this timescale, continental drift would be as apparent as the movement of boats are to humans. Anything that's working at the cosmic scale where the seemingly low speed of light sounds exhausting is most definitely working at this stellar perspective at the minimum. 14000 years of travel might as well be the equivalent of a 10 minute commute to the store.
Philosophically speaking, of course.
This leaves out the time component. Who's to say that a year is long? A galaxy a million light years away takes a million years to reach... and maybe that's a short amount of time, to the right observer.
Tangentially, I've long wondered about sci fi like Star Trek. Namely, even with FTL, how large can your interplanetary alliance be? How far away can the parliament be? Over what distances can you defend against common enemies? Trade? Culturally exchange ideas?
Even after all the stars die, the white dwarfs will continue to glow. And after eons, the last black holes will evaporate. The point is that the age of stars is only a tiny fraction of the lifetime of the universe. Maybe the speed of light makes sense at that scale.
But... I'm not happy with that theory. In a relatively short amount of time the expansion of the universe will increase faster then the speed of light. Which means it will be impossible to ever get information from the other side of the universe.
I find it very unreasonable that the universe imposes a speed limit on everything and then completely ignores it.
In addition to the insight, it reminded me to water a plant at a desk I no longer use. The plant's been with me through quite a bit and I have been neglecting it recently as I no longer see it regularly.
like not even on a human level, universally even on a grand scale the speed of light is almost torturously slow, there’s nothing philosophical about it
War only occurs if you have in the literal sense retarded elements in your advanced species and is nonsensical from an outside POV. A species this advanced would have fixed such shortcomings in itself long ago.
So no, I don't think they'd necessarily be very interested in watching primitive species go to war with primitive weapons.
For all we know the simulation of this universe is happening in their equivalent of an overengineered snow globe, us being an artifact nobody has noticed and that nobody would find particularly interesting if they did notice.
It's slow for humans to explore the cosmos.
"Slow" is meaningless without a frame of reference, and "humans" seems like a good frame of reference, since it's us -- and not plants or stars -- who are writing on HN to discuss this.
Because it's us, humans discussing this in HN, the frame of reference is implied and it's not necessary to spell it out.
Ents could fly to the stars no problem.
Makes me wonder if there might not be a bunch of star faring “slow life” out there that we don’t notice for the same reason a hummingbird doesn’t notice trees growing.
It’s always faster than you or I. Even if we zipped around at relativistic speeds it would still appear the same.
Yes, agreed. I find it a little depressing. An unimaginably huge universe, tantalisingly there, but completely out of reach.
Although for everyone else at least 5000 years will pass, so better say goodbye to family and friend.
Hm, not sure if that is really less depressing...
Also light isn't slow. A photon instantly travels to the end of time and yet it still takes a few minutes from the surface of the sun to us. Or about 100000 years from the center of the sun to its surface.
Of course building and fueling such a rocket is what's totally out of reach.
We'd need a device that could efficiently transform several kg of matter to photons.
Of course there's the pesky problem that for every N kg of mass you want to accelerate at 1G for that kind of a trip, you're probably going to need somewhere on the order of N billion kg of fuel to burn.
A starship capable of such a journey is surely large enough to bring all your friends and family along, colony-ship style.
For sure you're not just sitting there watching people get born, live and die in second and shrugging your shoulders.
Basically it would be like flying through explosive sandpaper. Each dust particle would be reduced to plasma, which creates problems of its own.
If you're accelerating there's also the Unruh Effect, which will raise the perceived temperature. By a lot.
There's no way to make this work with any kind of engineering we know about today.
In any case it's probably a moot concern as long as we are living under the twin tyrannies of Newtons Third Law and the Rocket Equation. Building a rocket that can accelerate constantly and noticeably for weeks, months, or even years on end in order to accelerate up to a velocity where Relativity starts to matter requires an absurdly large rocket. Like converting the mass of Jupiter into rocket fuel to make it to the next habitable solar system in a couple of centuries level of craziness.
"Extremely" and "very" don't cut it here. This is beyond the human ability to guess. You'd actually do at least some back-of-the-napkin math to give a real answer, and with a far enough trip, the answer may well become "Almost 100%".
Plus if you're traveling at near light speed, running into any matter at all would be pretty devastating for whatever craft you're in.
Edit: someone further down claimed that the math says that accelerating at 1G would get you to 0.1c in a month, so that's actually not that bad all in all. I still maintain that hitting any matter at those speeds might be unpleasant.
Minor problem is that we don’t have any technology that’s close to capable of that. And at 0.1c relativistic effects are barely noticeable.
Like are we at 0.1% or 0.01% or more orders of magnitude off?
The best speed for interstellar travel with technologies that current theory says should be within our reach can be achieved with a vehicle with a light sail pushed by a giant laser, that is powered by solar power. There is even a way to brake it when it reaches the target star. I forget what the predicted velocity was though.
This technology is basically the same as one that the Moties developed in the story, The Mote in God's Eye.
We do not yet have this technology. But we can show that it is plausible.
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
Please explain this. TIA
That means that when you get to speeds equal to c, your time runs infinitely slower and the distances are infinitely shorter. So if your clock is infinitely slower, so every travel at "c" speeds means that no time passes for you. And if your distances are infinitely shorter, all travels at "c" speeds cover any distance as immediate. So you could reach every point of the universe as if it was immediately closer and in no time at all.
So in the frame of reference of the photon, the moment it is created it has already reached its destination, be it wherever it is on the universe.
Of course we can never reach "c" as beings with mass, but we can get closer to that. So for example if you get to 99.99999999999999% of the speed of light, you could travel a distance of 54,794,520 ly and only one year would pass to you, while 54,794,520 years would pass on earth.
Do photons actually exist, in the traditional sense of physical matter.
Or are they just a convenient short hand to describe the transfer of energy via waves in the fabric or space time, if they dont experience the universe when passing through it but only when interacting with matter and matters "dents" in space-time.
Spacetime is like that, except North/South is space, and East/West is time. The more you travel through the spatial dimension (the faster you go) the less you travel through the time dimension (the less time passes for you). Photons are traveling completely through the spatial dimension (North/South) and so aren’t moving through the time (East/West) dimension at all, so from a photon’s perspective (if they had perception) no time ever passes so they would zip around “instantly” and never “experience” anything.
It is also why the speed of light is the fastest you can go. Once you are going 100% North, you cannot be going any more North.
Traveling 5,000 LY at 0.5 c will cause you the spaceship pilot to age 20,000 years. It's non-relativistic, inside that inertial frame. Clock second hands still sweep slow but noticeable circles.
Meanwhile, everyone outside of the spaceship is happening FAST, by your observations. You'll see stars turn red and go supernova.
- Titan, Io and Ganymede are only 2.5 days away - Pluto is about 23 days
Edit: Even at such speeds, we still can’t visit a nearby star system in a reasonable time-frame. Oh well.
Even if we could travel at 1 percent the speed of light, the "destination" would be inflating away from us at much greater relatavistic speed.
To your point, this is less an issue with solar or extra solar objects.
If you're travelling between points in the Oort Cloud, 1G should be more than sufficient to hit .1c on the trip.
At this point in humanity's history, I think that's more feasible than high speed traveling.
Perhaps this is really how AI achieves consciousness?
We know how to do exactly zero of those things.
If you have all of this why would you go to the enormous extra effort to move the habitat to a different solar system? Even if your civilization is so old that the star is a dim brown dwarf that's still plenty of energy for day to day life.
I remember someone pointing out that a generation ship could be problematic because you have one generation who decides to launch this expedition but will never see the end, multiple generations who didn't choose this life and won't get to see the benefits, and then one generation who actually gets to the planet but might not even want to be there. Without some kind of cryogenic sleep or relativistic speeds the whole thing might fall apart just because most of the people involved "didn't sign up for this" but they have to toil away anyway for someone else to benefit from it.
This makes me think of multi-generational migrations north out of Africa. There's only so much that can be passed orally losslessly. Eventually the group in north siberia after 20K years doesn't see living any other way.
That isn't really different from the way things are now. We are, in fact, traveling through the galaxy for many generations and none of us signed up for it. We just happen to be on a largeish ship and have no destination.
That's the point of the AI; it would generally replace that.
Of course, even if we stopped doing that, we'd need to figure out how to visit another place if our ship is passing close by. That also seems to pose a problem: both Voyagers are barely out of the exhaust fumes of our ship's motor, and getting so far took ~40 years.
That’s essentially the premise of Project Hail Mary. Good book.
He basically just has it work because the fuel difficulties are solved and bam, the main character can zip around nearby start systems at close to perfect C on a ship built with little more than our current 21st century technology. Fun, but not even in the most basic way an attempt at presenting any science seriously.
What makes it more amusing is that for many other parts of the main drama, he puts a lot of effort into making the descriptions and scenarios seem as realistic and science-rich as you could like. I suspect a lot of entertaining word salad there too though.
Think more about the difference between single celled organisms versus a multicellular organism: IE, the spaceship itself is alive and has a lifespan where interstellar travel is a fraction of its life. The people inside are like cells inside our body.
With a ship able to accelerate at 1G continuously, you can be at the edge of the observable universe in <50 subjective years [1].
[1] https://www.reddit.com/r/dataisbeautiful/comments/s4tbry/oc_...
There is a known way to achieve 100% fuel efficiency: antimatter. By storing equal parts matter and antimatter, you can fuse them to propel your spacecraft. It's unknown wether or not this kind of engine can actually be made.
Alternatively, and even more far-fetched, you could onboard a small singularity. Dumping anything into it will result in it being turned to pure energy at 100% efficiency, through Hawking's radiations. The smallest the singularity, the fastest it radiates, meaning you can sort of control the output. You can create singularities with very large particle colliders.
With 100% fuel efficiency you can probably sustain 1G for long enough to reach the nearest stars. You would need a very large spacecraft (on the order of kilometers) for a comparatively very small payload. And it would arrive completely empty at its destination, meaning no turning back. I think I saw someone do the math, but can't find it anymore.
Anyway, there are other difficulties. Travelling at .99c means tiny space dust now becomes very dangerous. So does radiations, all made extremely energetic by the Doppler effect.
On the plus side, continous 1G means you have artifical gravity for the whole trip.
The greater barrier is that the nature of the expansion of the universe prevents any real interstellar travel that has a "destination" in mind. Of course we might have some "FTL" or "near light speed" travel in futre, but if the universe is expanding infintely from every point in space at light speed, how could we ever "catch up" to objects we see even now?
Source: https://www.reddit.com/r/askscience/comments/sr7fuo/is_there...
As far as I know, anything going faster than the speed of causality violates causality. So what are you talking about?
But we don’t know that casualty is a law of physics, do we?
SR breaks down at both ends of the spectrum, at the event horizon of black holes and in Bose Einstein condensates. That proves that it is an emergent property of observations, statistical behavior of decoherent systems, and not a universal law.
I agree, but not because of the relative difficulty of the technology, but because we spend way more on entertainment than space exploration.
So the goal is to create engines that can take us close to light speed. Then the issue is braking (spacetime expands as you slow down…)
Everyone things that a game breaker technology is better engines, or fusion, or FTL, but they are wrong, the game breaker technology has already happened: 3D printing.
If we can manufacture things with minimal infrastructure using local resources, we can that is all we need.
And all of it reachable with simple nuclear power and technology we have today.
Nice.
We’ve got to preserve causality. :P
From the perspective of somebody in a ship moving at relativistic rates, distances would begin to physically contract, and time itself would begin to speed up relative to an at rest observer. Here [1] is a calculator to see what this all mathematically works out to. For instance, you could travel to Andromeda, some 2 million light years away, in about 28 years in a ship that was capable of sustaining acceleration at 1g for 28 years. Of course for everybody back home 2 million years would pass. So if we ever achieve ships capable of this sort of acceleration, life is going to get really weird and non-linear, so far as time is concerned.
And this isn't some just some weird fringe theoretical/mathematical thing. For instance GPS satellites have to compensate for time dilation because relativistic effects, though small in this case, would otherwise have a substantial effect. Another example is at things like the large hadron collider. As a convenient effect of relativistic effects, emergent unstable particles exist far longer than they 'normally' would before decaying due to the fact they're moving at relativistic rates.
In other words, this is all very real. The only questionable issue is whether we can discover some sort of an energy source capable of accelerating a ship at 1g for tens of years, and develop sufficient shielding for such a vessel. That's still very much in the domain of sci-fi, but simultaneously seems like something that one wouldn't be entirely surprised to see was discovered just a century from now. This was the most tantalizing possibility behind the EMDrive stuff. [2] Well that or infinite energy, but it seems that universe won't be broken quite so easily just yet.
[1] - http://www.convertalot.com/relativistic_star_ship_calculator...
be thankful things are far apart
a gamma-ray burst from a collapsing star closer than 200 light years away would destroy ALL life on earth
Until we make full use of robotics and 3D printing, there is no point of heading far. And we have all the tools.
Distant stars will not be settled by a fast small ship travelling from earth. They will be settled by a city sized monolith produced by harvesting and smelting an entire small moon
I don’t even think you’d need a whole moon unless it was a tiny one. Nonetheless, by the time we send a ship to another star, building these kinds of large self-contained habitats will be old hat.
Its relative! Sitting on a couch and watching the pixel move from the sun to the earth for 8 minutes feels incredibly slow but if you are actually traveling in a light speed aircraft then it won’t feel that slow.
2) it's assumed within the framework of the fictional universe that time dilation isn't taking place because the actual travel is occurring within an external frame of reference like "hyperspace" or a "warp field."
The Earth is about 8 light-minutes away from the Sun :)
even in a vaccum, light speed travel from the travelers POV still takes time, and said traveler would perceive time passing exactly as occurring in that local space. But yes you're totally correct, the observer on earth would in this time see only the briefest part of my journey's trail due to light from my journey taking "exponentially" longer to travel back to the observer.
That’s not just "relativistically instant", that’s literally instant in your frame. The time dilation becomes total at light speed, and length contraction collapses the entire distance in the direction of travel to zero.
Now, it’s true we can’t really assign a rest frame to a photon, so this is a thought experiment. But if you extrapolate the math, the conclusion holds: no time passes for something traveling at light speed.