25 ms·
How far could a spaceship go if we never ran out of thrust? (2020)
- philiplu 5y agoFor a hard science fictional version of this, check out Poul Anderson’s “Tau Zero”, from 1970, according to Wikipedia. I read it a few years after that, and it’s stuck with me since. A ship with a Bussard ramjet runs into troubles and has to keep accelerating, into the far future.
- quickthrower2 5y agoI never knew you could get that far in that amount of time (experienced by passengers) with just 1g of force so it’s thoroughly interesting and in some sense everything is quite close: as long as you are OK with a one way ticket.
- CodeGlitch 5y agoAlso why stop at 1g? People could be trained to live in 1.2 or even 1.5g.
- londons_explore 5y agoA one way ticket with no messages back to/from home.
- mattowen_uk 5y agoFor such a long trip, the only logical ship type would be a self-sustaining generational colony ship full of hundreds of people. The concept of 'home' would quickly shift from being the Earth to being your ship, so staying in contact with your origin planet would become irrelevant.
- quickthrower2 5y agoMight be why the simulator is the most important technology in star trek, to keep people sane, connect with nature etc.
- jonplackett 5y agoThe thing they never address - booking slots. That simulator would never be available!
- mjevans 5y agoWe the viewers follow high ranking officers on a capitol starship. Surely this cushy position comes with a well equipped post on a vessel that has a good number of such units. Enough so that Voyager had the meme of holographic crewmembers. I don't know if RedDwarf (Rimmer) or some other scifi show got there first.
- jonplackett 5y agotrust the internet to have already calculated the answer to this question (you can have 10.8 hours per month = 30 minutes a day - not bad!) https://www.reddit.com/r/startrek/comments/3aajfy/how_much_holodeck_time_can_i_have_on_the/ https://www.reddit.com/r/startrek/comments/3aajfy/how_much_h...
- nsxwolf 5y agoIf it's anything like VR, a bunch of the people on the ship would lose interest and rarely use it, leaving lots more time for the devotees.
- Spare_account 5y agoPresumably a bunch of people could book sessions in one simulator at the same time and simulate multiple simulators inside the simulation, massively increasing the capacity of the top-level simulator.
- Dylan16807 5y agoWhy do you need a self-sustaining generational colony ship to go 30 years? Especially in the space future when we should be able to slow aging down at least a moderate amount.
- DonHopkins 5y agoIn space, they just call the "space future" the "future". ;)
- senectus1 5y agoafter the last year I imagine quite a few people would put their hand up for that. but also, what about deceleration? You gotta stop some time to smell the roses... so would you cut that acceleration time in half to decelerate?
- simiones 5y agoIt's important to note though that this kind of ship is still impossible as far as I remember - even with matter/antimatter reactions (which theoretically gives you E = mc^2 energy, the maximum possible per kg), you can't get enough energy to accelerate to the mass of the fuel to 1g, nevermind the rest of the ship, for the duration required for interstellar travel.
- grey413 5y agoThe amount of energy required for fast interstellar travel is mind-boggling. People do not comprehend the scale. Even with ridiculous things like massless fuel it would take multiple times the entire yearly energy expenditure of the earth for an ISS sized ship to travel 10 light years before the passengers died of old age.
- quickthrower2 5y agoIt’s almost like we never need to do it: just send seeds of life out into space: if we send people we can never hear from them again anyway. We can’t get the information back. So it’s mostly a hedonic exercise: a one way adventure holiday for the crew.
- adrianN 5y agoThe social effects of relativistic time dilation are an important topic in "The Forever War".
- neartheplain 5y agoFantastic sci-fi novel with continuing modern relevance. Often interpreted as metaphor for the author's experience in the Vietnam War, and his return to American society after what felt like a period of otherworldy time-dilation. The graphic novel version is great too, if you can find a copy: https://en.wikipedia.org/wiki/The_Forever_War_(comics) https://en.wikipedia.org/wiki/The_Forever_War_(comics)
- rbanffy 5y agoInteresting to note that when you are travelling close to c, even intergalactic vacuum requires a lot of mass ahead of you so the ship is not vaporised. Remember that when you are travelling to that galaxy 18 billion light years away, you’ll hit every photon it sent our way over 18 billion years in just about 45 years.
- bobsmooth 5y agoI always knew intergalactic hydrogen might be a problem but I never considered the effect of travelling really fast on photon absorption.
- dvdkhlng 5y agoIf you travel close to C, those photons will be blue-shifted into (depending on velocity) very energetic photons (x-ray, gamma spectrum) that may be rather difficult to shield against.
- Koshkin 5y ago> close to C As a programmer, this gave me this warm feeling...
- weregiraffe 5y agoBut when you accelerate even more, it will be C++.
- hateful 5y agoSpecial Relativity states that it's time that changes, not the speed of light. C is constant regardless of your reference frame. So, it's still C, but instead, it will take a lot longer to complete your project. You're definitely going to miss your deadline.
- rbanffy 5y agoThe hydrogen may be a problem well before the light or CBR become another.
- londons_explore 5y agoSay you take the one-way ticket to travel to a far off galaxy at 1g acceleration to go mine space-diamonds... What when someone else in a few hundred earth years invents the 1.1g rocket to go mine those same space diamonds? They will arrive millions of (local) years before you. By the time you arrive, the space diamonds will be all mined and you'll be seen as a cave man. That reason alone means it's never worth departing on a long journey, because someone else always has an incentive to overtake you and get there millions of years sooner.
- adrianN 5y agoAha, but if everyone thinks that way you will actually be the only one daring enough to embark on that journey and have all the space diamonds for yourself!
- ehnto 5y agoBy that reasoning, no-one ever leaves. If no-one had ever left, you may as well have left and be there already. I think the reason to leave will have to be something other than space-diamonds, or other monetary needs. More like planetary conquest and scientific advancement.
- jusssi 5y agoIn addition, something approacing from opposite direction might already be there when you decide to launch, digging away at the diamonds. Or a local star might have gone nova and vaporized the whole diamond field.
- RavlaAlvar 5y agoOr someone who invented a device that can fold space time.
- vidarh 5y agoQuite a few scifi stories have explored the idea of someone leapfrogged that way. I think it'd be a major concern of sending someone that way. [For one light take on this, the original Marvel "Guardians of the Galaxy" (the year 3000 versions) have Vance Astro, Major Victory, go on a 1000 year journey to Alpha Centauri, only to find other humans got there centuries earlier and were waiting for his arrival]
- sudhirj 5y agoThe implications of time dilation when moving near c are also explored in the Three Body Problem trilogy, and pushed to the extreme as well. It’s quite a mindfuck if you still have ties to the place you’re leaving, but interesting if you don’t. There’s all the interesting idea of just accelerating forever, till the end of the universe (which comes faster than you think if you’re going that fast).
- simonh 5y agoWe're really spoiled by modern rapid global travel. In the 1930s half of my maternal grandmother's family emigrated to New Zealand. I've only ever met two of those relatives once in the 1990s, but before jet travel such contact was impractical for most people. That's why whole family groups, or even communities would move together.
- edna314 5y agoThe time dilation aspect in space travel is the most neglected in popular sci-fi. In many of these, there are intricate installations of some sort cryogenic sleep devices because the script authors assume that it takes you 150 years of travel at light speed to get to a place that is 150 light years away.
- CodeGlitch 5y agoInterstellar explores this idea really well. Also see Andy Wiers' new book "Hail Mary", which I can thoroughly recommend. In Hail Mary he doesn't use cryogenics but a different mechanism.
- nahuel0x 5y agoInterstellar merged relativity effects with emotional ones, that's a brilliant literary stroke analogous to the ones from the s.f. masters.
- eesmith 5y ago... what? It's been part of SF for decades. The first three that come to mind are: Heinlein's "Time for the Stars", Haldeman's "The Forever War", and Anderson's "Tau Zero". From those titles, a DDG search finds http://sf-encyclopedia.com/entry/relativity http://sf-encyclopedia.com/entry/relativity listing more, also containing the line "Very many sf stories use relativistic time dilation for one-way Time Travel into the future."
- air7 5y ago> "In fact, so long as you kept adhering to this plan, you could choose any destination at all that’s presently within 18 billion light-years of us, and reach it after merely 45 years, max, had passed. That ~18 billion light-year figure is the limit of the reachable Universe, set by the expansion of the Universe and the effects of dark energy. Everything beyond that point is currently unreachable with our present understanding of physics" What happens if I just keep going?
- hoseja 5y agoNotice the "presently".
- Lariscus 5y agoYou would never reach your destination and at some point you would be stranded in dark space. This kurzgesagt video has some info on this topic.[1] [1] <https://www.youtube.com/watch?v=uzkD5SeuwzM https://www.youtube.com/watch?v=uzkD5SeuwzM>
- stouset 5y agoI don’t quite understand this. I think I’d maybe understand if space dilated to the point where you couldn’t quite hit that edge. Though now that I say it that “solution” seems to come with a whole bunch of problematic consequences. But “not getting to anything past the furthest thing we can see from earth today” seems fundamentally incompatible with the idea of reaching those farthest points in a reasonably bounded timeframe. There is stuff beyond the limits we can see, it’s just further than light has had a chance to travel so far (and may ever travel). My intuition is that as you approached those far objects, you’d observe them rapidly evolving forward in time until they reached their “present day” situation, able to see billions in light years in all directions with Earth right at the edge. But then what happens when you look at Earth? Surely you don’t see it’s billions of years old past. You’d have to see it at least as old as it was when you left. But something doesn’t seem quite right about that to me. Surely I’m missing something.
- est31 5y ago
- eesmith 5y agoThose interested in this topic may also like the extensive background materials and guidelines at Project Rho, eg, http://www.projectrho.com/public_html/rocket/slowerlight3.php http://www.projectrho.com/public_html/rocket/slowerlight3.ph... .
- deleted 5y ago[deleted]
- littlestymaar 5y agoAlastair Reynolds' novel Pushing Ice (2006)[1] covers exactly this topic: a bunch of humans are trapped on an alien spaceship accelerating indefinitely, and all the involved relativistic effects are covered in the book. While it's not Reynolds best book, it's definitely worth reading just for the clarity and accuracy of the description of the relativistic effects (Reynolds is a former ESA astrophysicist). [1]: https://www.goodreads.com/book/show/89186.Pushing_Ice https://www.goodreads.com/book/show/89186.Pushing_Ice
- milansm 5y agoWhich book would you consider his best? I’ve only read House of Suns, and it was great.
- littlestymaar 5y agoNot an individual book, but the entire Revelation Space series is one of my favorite SF piece ever.
- soylentcola 5y agoAlso one of mine. This thread got me looking it back up and it appears there's a 4th novel coming out later this year (I didn't know about this, so perhaps you'll be equally glad to learn of it!)
- JamesBrooks 5y agoHouse of Suns left me sad that it was a standalone novel, I was itching for more!
- lreeves 5y agoThere is another novella in the universe called Thousandth Night! I thought it was excellent.
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- bencollier49 5y ago"spacecrafts" - urgh! Who wrote this?
- deleted 5y ago[deleted]
- jillesvangurp 5y agoRelativistic speeds are a plot point in Andy Weir's recent book "The Hail Mary Project". You might know him from the Martian a few years ago. Scott Manly did a Youtube episode on all sorts of weird propulsion mechanisms that people have come up with over the years a few months ago: https://www.youtube.com/watch?v=QEZv_OXA_NI https://www.youtube.com/watch?v=QEZv_OXA_NI. There are some interesting concepts in there. Including the anti matter based concept discussed in the article. Particularly fusion looks like it might get us some interesting amounts of delta v.
- JoachimS 5y ago> Relativistic speeds are a plot point in Andy Weir's recent book "The Hail Mary Project". You might know him from the Martian a few years ago. Just read the book and can highly recommend it. One of the good thing about it is that the main protagonists are nice, curious and friendly. No backstabbing, suprise turns of evilness to create suspense. A pleasant read.
- vagrantJin 5y agoCan confirm, it is a really good read. I especially liked that the protagonist really does things a normal person would do despite the extraordinary circumstances. I wish hollywood could take notes.
- nkrisc 5y agoIt’s why The Martian is one of my favorite movies (and book, of course). No evil, conniving, contrived antagonist designed to be hated. It’s just everyone working together against the most unforgiving antagonist of all: the universe itself. I don’t want to watch movies or read books where people are just awful to other people, I can open the newspaper on any given day to find that.
- vagrantJin 5y agoThe martian was a fun read and undoubtedly a classic. I personally dont mind a well thought out antogonist who is very human.
- Koshkin 5y agoSure, with the comfortable acceleration of g during the first half of the journey and decelerating during the rest of it, I could arrive to, say, Andromeda galaxy in a few dozen years. The biggest question, though, for me is: OK, I’m here, now what? (Having a vivid imagination, as a child I once imagined myself standing on the Moon’s surface, looking at the distant Earth shining just above the horizon and the eerie landscape below. The first and the only thought I had at that moment was: “What the hell am I doing here?”)
- praptak 5y agoSurely astronomers have a list of objects which are expected to be interesting from a closer distance?
- Torkel 5y agoThe year is 1492. You're imagining standing on the shore of a vast continent, unexplored by your people. The only feeling/thought you have at that imagined moment is “What the hell am I doing here?” That is perfectly reasonable! But I hope you can appreciate that the imagined feeling/thought is not shared by everyone.
- stavros 5y agoThat's not very comparable, because you could easily live a very fulfilling life in a new continent (well, except Australia, I guess?), but being on the surface of the moon would be a constant struggle for survival.
- hutzlibu 5y agoSlightly related: I just discovered Andymon. A 1982 sci-fi novel, where a interstellar spaceship reaches the destination star, after travelling a very long, but unknown time (part of the plot). I do not want to spoiler too much, but it was written by a academic physics/philosopher and his wife a mathematician. Deep shit. Should be standard read in schools.
- drittich 5y agoDo you know if there's an English translation?
- hutzlibu 5y agoI assumed there is, but also could not find one right now. Would be a shame, if there isn't.
- vagrantJin 5y agoYou over-estimate teenagers. But worst of all, you over-estimate the department of education.
- hutzlibu 5y agoI am not a fan of mandatory books, but I know I would have loved to read and talk about this book in school. It covers everything scientific, as well as philosophical existential questions.
- andrewflnr 5y agoTeenagers are idiots in many ways, but also hunger for real, deep ideas. Maybe if they weren't so consistently underestimated they would take things more seriously.
- vagrantJin 5y agoI apologize, ofcourse they have a hunger for real, meaningful and deep ideas but, they are still pretty dumb. Not dumb as in lacking intellectual ability but dumb as in willingly stupid. Thats the key. No shade but pop culture is basically a "teen spirit" transformed into profit by BS Inc. And ofcourse the small issue of sex being 80% of what's on their mind. Perfectly natural and healthy.
- jcims 5y agoThe ‘specific impulse’ of a rocket engine is one measure of its ability to convert the energy in its fuel into forward thrust. Its unit is ‘seconds’, and its measure could be interpreted as ‘how long could one pound of fuel produce one pound of thrust’. If your rocket starts off 2/3rds fuel by mass, this will result in an average acceleration of 1g as the mass of the fuel is consumed. The most efficient chemical rockets we have today have a specific impulse in the ~470 second range. The highest specific impulse thrusters of any sort that we have in wide use today are ‘ion thrusters’, which have specific impulses in the 50,000 second range (but can’t generate much thrust at all). So 10-12 hours at 1g is about as much as we can do with existing hardware.
- Taek 5y agoI've always pretended to myself that I understand what impulse means but today you've helped me actually understand it. Thank you!
- fouronnes3 5y agoGP is a nice reverse engineered explanation, but the actual origin of using seconds as a unit is to avoid having to compare metric and imperial units of speed. Isp is just exit velocity divided by g and it's conveniently in seconds, a pretty universal unit. And "one pound of thrust" only makes sense when you're in Earth's gravity field with gravity losses. Otherwise it's more precise to use Newtons for thrust.
- jcims 5y agoI use it because even after being an Estes nerd as a kid it was the first explanation that actually made sense to me.
- kbenson 5y ago> conveniently in seconds, a pretty universal unit. Thankfully! Imagine if systems/cultures commonly differed in fundamental measures of time, just as they sometimes do for volume, distance, weight, etc.
- wombatmobile 5y agoAmerican singer Elvis Presley explored this theme in 1968. https://youtube.com/watch?v=7Skrq8unUlE https://youtube.com/watch?v=7Skrq8unUlE
- teekert 5y agoSince mass increases with speed, will this spaceship collapse and become a black hole? Or is it just massive from the observer reference frame?
- nuccy 5y agoMass is not increasing in the frame of reference of the ship, so no, it will not collapse into a black hole regardless of how much energy it received externally (e.g. laser beam from Earth) to accelerate closer to the speed of light.
- teekert 5y agoBut it will attract massive objects (like stars) at some speed then?
- FartyMcFarter 5y agoForbes's UI is infuriating.
- deepsun 5y agoAt relativistic speeds, you'd be vaporized, or at least ionized by interstellar gas, e.g. there are about 1 atom of hydrogen in one cubic cm. There was a paper considering making a shield against it, either lead, or electric field, or magnetic field, and resources required for it.
- cookieswumchorr 5y agoshit, looks like i started packing too early
- dghf 5y agoOne thing I've never been quite clear on: > If it weren’t for Einstein’s relativity, you might think that, with each second that passes by, you’d simply increase your speed by another 9.8 m/s. If you started off at rest, it would only take you a little less than a year — about 354 days — to reach the speed of light: 299,792,458 m/s. Of course, that’s a physical impossibility, as no massive object can ever reach, much less exceed, the speed of light. > The way this would play out, in practice, is that your speed would increase by 9.8 m/s with each second that goes by, at least, initially. From the point of view of an external observer, this seems clear enough: the ship's acceleration would reduce, at first gradually, then ever more sharply as its velocity approached c. But what about from the point of view of the ship's crew? Would they also measure a drop in acceleration -- e.g., would they weigh less? Or would it be that they would measure the same acceleration, but the final picosecond (according to their clock), which would without relativity push their velocity to and past c, instead stretches out infinitely, thanks to ever-increasing time dilatation?
- cout 5y agoAs I understand, the crew would not notice any difference, since time is slowed in their frame of reference relative to that of an observer.
- ruszki 5y agoThe crew would feel as they accelerate by a constant 9.8 m/s^2. They would not feel any slow down in time. For an external observer, the crew would never reach speed of light, but they would close the gap continuously.
- JohnPrine 5y agoso after 354 days would the crew believe they had exceeded the speed of light?
- ninkendo 5y agoIf you could somehow indefinitely maintain 9.8m/s^2 acceleration, as you get really really close to c, your definition of a “second” becomes so long that it basically goes to infinity (time starts to travel infinitely slow for you.) Maintaining 9.8m/s^2 at such velocities starts to require infinite energy. If you were somehow able to reach c, your internal clock would be so slow (and the rest of the universe would be going by so quickly) that would experience the end of the universe essentially instantaneously. So the practical answer to what the crew would experience on the 355th day of 1G acceleration is: “That’s impossible.” The energy requirements approach infinity, and so does the speed of time for the rest of the universe they’d see out their window.
- api 5y agoThe theoretical limit is "to the edge of the Hubble horizon, as long as you don't mind it being a one way trip." As you approach 'c' time dilation shrinks time for you. Keep accelerating and eventually a million years outside your reference frame is mere days or hours inside the spacecraft. You could travel to the Andromeda galaxy or beyond as long as you were okay never returning to Earth or returning to a different geological epoch than the one you left. Go far enough and the sun might be in its red giant phase when you get back. You may have aged a few years or decades. This of course requires stupid amounts of energy and theoretical near maximum specific impulse, what I once heard called a "physicists' nightmare propulsion system." Something like a "photon rocket" or a relativistic velocity ion drive (propellant exit velocity near 'c') plus a very efficient fusion or antimatter reactor might be able to get you there. It was called a physicists' nightmare because if containment fails you become a flash of gamma rays in less than a nanosecond. One of my favorite wild speculations is that hypervelocity massive particles like the "OMG particle" are the jet wash from someone's engine.
- Robotbeat 5y agoCan someone calculate at which point a 100 ton spacecraft accelerating at a constant 1gee (local) would have a total kinetic energy exceeding the mass energy of the entire (observable… as in, within our light cone) universe?
- scotty79 5y agoI'm not sure but I think that with constant acceletation, your kinetc energy raises with time squared. And the whole c speed limit just affects how kinetic energy relates to speed.
- wuliwong 5y agoThis video from the "Cool Worlds" youtube channel is a fun walk through this idea. https://www.youtube.com/watch?v=b_TkFhj9mgk https://www.youtube.com/watch?v=b_TkFhj9mgk
- dctoedt 5y agoOne of Heinlein's juvenile novels (Have Spacesuit, Will Travel?) describes TFA's concept of accelerating at 1g until the halfway mark, then doing a "skew flip maneuver" (I think that was the phrase Heinlein used) to decelerate at 1g. [0] [0] https://en-academic.com/dic.nsf/enwiki/2241027 https://en-academic.com/dic.nsf/enwiki/2241027
- irrational 5y agoSo, if you constantly accelerate for 45 years you will travel 18 billion light years to the edge of the observable universe. But, if you continue for another 45 years you won’t move beyond that point? Or do you move beyond that point but don’t reach anywhere, it’s all darkness? Or do you seem to stand still while the observable universe behind you expands past you to where you can no longer see it?
- jamesdmiller 5y agoDoes the expansion of the universe reduce how much you have to slow down if you wish to land on a very distant planet?
- platz 5y agono because expansion only happens on the largest scales
- jamesdmiller 5y agoBut if I travel for 45 years at 1-g doesn't the largest scale of the universe become significant to my travels?
- tomxor 5y agoAnd all at 1g... I wonder what forces the human body is capable of adapting to over a long period. What happens if say we double the thrust, presumably halving the timescales and doubling the experienced "gravity"... would a human body be able to adapt and get stronger? or would we experience adverse side effects? (not necessarily mutually exclusive). It could even be a way to acclimatise to a different planet's mass before arriving. [EDIT] Looks like 2g is reasonable. The limit is higher but it sounds a bit ridiculous, astronauts would all have to compete in the strongman competitions for 4g. Any higher and we wouldn't be able to walk without breaking our bones. https://www.discovermagazine.com/the-sciences/whats-the-maximum-gravity-we-could-survive https://www.discovermagazine.com/the-sciences/whats-the-maxi...
- P4u1 5y agoThanks, I was wondering the exact same thing!
- rtkwe 5y agoThat number would probably also change over time especially as people grew up in that gravity, putting more stress on their bones which should cause them to grow thicker (see ancient skeletons of longbowmen for a small example and imagine that the extra forces are there all the time).
- deleted 5y ago[deleted]
- kazinator 5y agoIf you use as much thrust as you can, you can get wherever you are going in less time in the moving frame of reference. So that it to say, the difference between going say, 0.99C and 0.9999C is not that significant from the outside frame of reference, being just 1%, the difference in how much time slows down inside the ship is large.
- dehrmann 5y ago> When we take a look at conventional rockets that we launch from Earth, it surprises most people to learn that they barely accelerate more rapidly than gravity accelerates us here on Earth. This is actually pretty obvious when you look at a launch and how slowly it accelerates.
- LeoPanthera 5y agoThis concept is explored in the second sequel to "2001: A Space Odyssey", "2061", albeit without approaching relativistic speeds. Clarke explores the idea that in a future where fusion reactors can be built, a spacecraft can have a fusion-powered motor for which the fuel is simply water. In the book, a spacecraft travels from Earth (or maybe Mars, it's been a while since I read it) to Jupiter, and does it the "brute force" way by simply pointing at Jupiter and thrusting at 1G until they are half way there, and then turning around and slowing down at 1G until they arrive. This has the bonus side effect of allowing the spacecraft to have normal gravity inside it.
- wavefunction 5y agoForever? Seems self-evident.
- btbuildem 5y agoSo in a way, this is time travel. If you wanted to see what the world looks like in five thousand years, you could get on a spaceship, accelerate way out to wherever and back, and voila! you've fast-forwarded five millennia. A fascinating thought. The ship and crew would surely be long forgotten. You may be greeted as an alien visitor, until the people of that time recognize your relatively ancient technology from fragments of historical records. Too bad you speak a language nobody else even remembers. Or perhaps you emerge as gods on a pillar of fire from the sky, witnessed by the primitive-again survivors of whatever has played out since you left. I'm strangely tempted. If you offer me a ticket on such a ship, I might just come along.
- justsid 5y agoDon’t forget to become a bubble boy to avoid catching all of the new diseases that you have 0 immune system protection against.
- journey_16162 5y agoIn 5,000 years from now the medicine will be so far ahead it would probably not matter.
- wildmanx 5y ago"If we never ran out of thrust, we could hypothetically reach anywhere in the Universe that a photon emitted today could reach." versus "I am a Ph.D. astrophysicist" I'm confused. In other words: How is he planning to catch up to a photon?
- maweki 5y agoNot catching up. But reaching the destination. That's limited though, as space expands. And any place is reachable that the photon is able to reach as these parts* are not expanding faster than the speed of light. * The whole space between start and destination, of course
- valiant-comma 5y agoSaturn Run (by John Sanford and Ctien) explored using a VASIMR propulsion system to maintain long-term thrust. Without giving away spoilers, I can say I enjoyed the overall story and intrigue. Sort of hard sci-fi geopolitical thriller, and the authors did their best to avoid hand-wavy physics.
- journey_16162 5y ago27,000 light years in just 20 years. This is crazy, I never would have thought these relativistic effects have such impact. I guess we could create a travel into the future this way if the rocket was designed to eventually come back to Earth. I was wondering, what if there was a spaceship circling outside the solar system at near light speed (not dwelving into whether it is possible ever to design such a ship or what the centigular forces inside would be), if there were people on such ship, that would experience 27,000 years in 20 years, would it be possible to communicate with them given the close proximity? Wouldn't it be weird that they are experiencing time in a much different way? Heck, even with a rocket that is simply moving away from Earth, the messages that are sent should eventually reach the ship? (because it's not travelling faster than light, and at times it's even slower) How can the ship receive 27,000 years worth of messages in 20 years?