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.
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.
Yes, agreed. I find it a little depressing. An unimaginably huge universe, tantalisingly there, but completely out of reach.
- 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.
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.
For sure you're not just sitting there watching people get born, live and die in second and shrugging your shoulders.
"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%".
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.
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.
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.
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.
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?
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
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.
A starship capable of such a journey is surely large enough to bring all your friends and family along, colony-ship style.
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.
Perhaps this is really how AI achieves consciousness?
We know how to do exactly zero of those things.
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.
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.
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.
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.
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…)
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...
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."
Nice.
We’ve got to preserve causality. :P
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.
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.
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
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.
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.
It’s always faster than you or I. Even if we zipped around at relativistic speeds it would still appear the same.
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.
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.
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.
I agree, but not because of the relative difficulty of the technology, but because we spend way more on entertainment than space exploration.
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...
Also thanks to the view-source I learned that it offers different units, including busses, Great Wall of China, etc
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
Mining asteroids for space resources sounds great, right up until you consider the distances involved. Living on Mars - yes, we really should - but you sure aren't going to support a colony long-term from anywhere but local resources.
A friend once asked if I couldn't show the planets in orbit rather than lying flat on a plane. I could, of course, but this is ray tracing. What do planets actually look like to human eyes from Earth? Just tiny dots.
If I were to show them in their proper orbits at scale using perspective projection, I'd only be able to render one planet large enough to be visually interesting. The rest would appear as small dots. I didn't want to use an orthographic projection, as it wouldn't reflect how we actually see the universe.
Those were, of course, limitations of a still image. An interactive page like the one in the original post does a fantastic job of conveying the vast scale of our solar system, both in terms of the sizes of the planets and the immense distances between them.
If the sun would be the size of a coin, then earth would be around 2m away from it and so small you could barely see it.
If ~1.0C is the fastest man can travel, that's still pretty good. Alpha Centauri is in reach (less than five light-years).
Maybe it would make sense if you could convert the mass of Proxima Centauri into rocket fuel to fund more expeditions? That seems like a fairly long term plan though.
Exploration is what humans do. If Alpha Centauri is only 5 years away, you can bet we're sending people there no matter what. Permanent colonization only becomes a priority in an existential event, and if we eventually achieve ~1.0C travel then that implies our tech is at a level we'd be colonizing Mars and a few moons long before we think about leaving the solar system.
Even getting to 0.9C is going to be very very hard for humanity.
https://www.dwitter.net/d/26521
The red bit is the sun. 1000 kilometers per pixel, and 1000 seconds per second.
They all fit onto the screen by looking through the orbital plane, as if through a telescope from a distant world, i.e effectively an orthographic projection. The orbits are accurate in terms of mean orbital distance (in reality there is slight perturbance) and sidereal periods.
Here's the js anyway:
for(i=10;i--;x.fillStyle=R(i-8||255),x.beginPath(x.fill()))x.arc(960+[45,29,14,8,2,1.5,1,.6,0,0][i]*1e5*S(t/5e3/[165,84,29,12,2,1,.6,.2,1,1][i]),540,[24,25,58,69,3.4,6.4,6,2.4,696,2e3][i],0,7)
Surprisingly the precision used in those encoded values is enough at 1000km per pixel (I checked).
The reason there are 10 radi is for 8 planets + sun + drawing the black backdrop (2e3): [24,25,58,69,3.4,6.4,6,2.4,696,2e3]
I've seen several, Planet Trek in Wisconsin is a good bikeable one with high quality signage. The sun is downtown, the moon is the size of a peach pit, Pluto is ~20 miles away.
#saturn {
position: absolute;
left: 412397px;
height: 34px;
width: 65px;
fill: #ffa043;
}Who the hell decided to make EMU’s??
https://en.wikipedia.org/wiki/Planetary-mass_object#/media/F...
EDIT: And Pluto is smaller than all the moons almost anyone has heard of.
https://mass.pbslearningmedia.org/resource/hawking_genius_ep...
It's a hands-on, practical example of how far things are away that we can easily visualize. I highly recommend the rest of the series as well. It's one of the best science shows ever produced. It shows the practical path of scientific discovery. You can watch is on the PBS app, which requires a $60 a year pass. Highly worth it. (I have no affiliation with PBS)
Sun diam 1,400,000 km
Eth diam 13,000 km
Sun dist 150,000,000 km
Mon diam 3,500 km
Mon dist 300,000 km
Simply put, imagine a yellow beach ball the size of a washing machine located a block and a half away from your house, a blue marble being the earth on one side of your keyboard and a peanut being the moon on the other side
https://www.youtube.com/watch?v=0fKBhvDjuy0
Interestingly, that Hawking visualization makes all the same affordances mentioned in the 1 pixel visualization. They show the earth and moon to scale, then the video shows an aerial view with all the planets much too large. Jupiter is 2x the size of the sun. Saturn and its rings 2x that.
Like, building a fully self-sustainable underwater city or moon base would be far more in reach. It feels that SpaceX should start with prototyping these safer alternatively before overreaching to something 100x more challenging and dangerous.
It may well be beyond our ability to practically apply those technologies at the required scales and reliability levels, but that's hardly unimaginable.
Unless you consider launching a lead-lined spaceship "within our tech."
The marsonauts won't die before reaching Mars, but their lifespans will be significantly shortened.
I've been beating this drum for years. Elon is 100% focused on building the rocket that can get to Mars and neglecting absolutely everything else about the project. Where is the self contained biosphere pilot program on Earth that tests the Mars habitat? To be anywhere close to Elon's timetable it needs to be running today, and honestly it should have been running years ago. Given the extreme reliability requirements it needs long term testing to build any confidence at all in the numerous technologies involved. The closest model we have is the ISS, and it's mostly shown that we aren't ready for a Mars habitat. The ISS requires way too much maintenance and ground support.
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
https://en.wikipedia.org/wiki/Breakthrough_Starshot
https://interestingengineering.com/innovation/mark-zuckerber...
Yeah, that Googol often doesn't work.
I believe the scientific record is drawing a consensus on this as the moon's origin but the wild sparseness of space just makes this sound really unusual.
Also crazy how far Jupiter's gravity can keep a moon??
That's why so many people were taking pictures of Mars back in January, when it was actually possible to take see detail. Right now it just looks like a red orb.
If the moon were only 1 pixel - https://news.ycombinator.com/item?id=39686916 - March 2024 (1 comment)
If the Moon Were Only 1 Pixel (2014) - https://news.ycombinator.com/item?id=32936581 - Sept 2022 (108 comments)
If the Moon Were Only 1 Pixel (2014) - https://news.ycombinator.com/item?id=27573172 - June 2021 (69 comments)
If the Moon Were Only 1 Pixel (2014) - https://news.ycombinator.com/item?id=21735528 - Dec 2019 (82 comments)
If the Moon Were Only 1 Pixel – A tediously accurate map of the solar system - https://news.ycombinator.com/item?id=13790954 - March 2017 (81 comments)
If the Moon Were Only 1 Pixel – A tediously accurate map of the solar system - https://news.ycombinator.com/item?id=13217129 - Dec 2016 (11 comments)
If the Moon Was Only 1 Pixel - https://news.ycombinator.com/item?id=12038584 - July 2016 (4 comments)
A Ridiculously large accurate scale model of the Solar System - https://news.ycombinator.com/item?id=10330303 - Oct 2015 (1 comment)
If the moon were only 1 pixel: a scale model of the solar system - https://news.ycombinator.com/item?id=7551423 - April 2014 (17 comments)
If The Moon Was Only 1 Pixel - https://news.ycombinator.com/item?id=7341690 - March 2014 (178 comments)
tedious=true, basicallyLame=true, is1px=false
> All these distances are just averages, mind you. The distance between planets really depends on where the two planets are in their orbits around the sun.
In the age of sail, people were perfectly willing to spend months in transit .
Transit times for most objects of commercial interest (i.e. upto moons of Saturns) is only in years if you use a low energy/Delta-v Hohmann transfer orbits and/or gravity assists as is common today for probes.
Direct transfer would be expected for human transits , those can be fairly quick . Transfers to mars within the next 1-2 decades is doable in 6months or less.
There are no fundamental breakthroughs needed to go any orbits we would be interested in 1 year or less by end of this century.
On the other hand I do agree going interstellar is a whole different scale of empty and without near light speed (even with ) is probably out of reach .
Could the planets and moons ever all be aligned like this when viewed from an infinite distance?
andersco•7mo ago
IggleSniggle•7mo ago
https://hmijail.github.io/1-pixel-wealth/
zurfer•7mo ago
arrowsmith•7mo ago
E.g. it gives Jeff Bezos's net worth as $139 billion, but today it's $228 billion.
athenot•7mo ago