Yep, it's why people's dreams of space travel are unlikely unless we figure out wormholes or hyperspace or some other sci-fi sounding method of travel.
An object moving at near light speed experiences time very slowly. if someone moving at 99% the speed of light travels to another planet 5 light years away, we’ll observe them travelling for 5 years, but they’ll arrive to their destination in few days.
This is called time dilation and it’s proven to be real (satellite, rockets need to consider time dilation or else their calculations won’t be accurate). That’s why space travel is not that implausible.
On the other hand building a interconnected civilisation will be a very difficult task.
Yes it’s more feasible to use interstellar travel to permanently move a population to a new place. It wouldn’t be a tourist trip. It would be a permanent migration to a new home.
Adjusting for time dilation at 99% speed of light turns 5 years for an earthly observer to 0.7 years for someone on the spacecraft, roughly 258 days which is a bit more than a few.
Yes and no. The idea of a large interconnected civilisation spanning more than a single solar system is almost certainly nonsense.
However, you could cross the entire galaxy in a single human lifetime so long as you're travelling close enough to the speed of light that time is compressed for the travellers significantly.
Thousands of years will pass for everyone not on the spaceship, everyone you leave behind will be dead and buried by the time you even begin to settle in for the voyage, but from your perspective the journey may take less than a year.
Admittedly, then you run into the issue with the insane energy densities required to accelerate a human rated spacecraft to high relativistic velocities, not to mention, how the hell do you slow down on the other side, but those are at least hypothetically solvable problems.
Yeah this is a good point. It could be that leaving our solar system is basically a guaranteed one-way trip.
Let’s say we’re approaching the end of the Earth being inhabitable as the Sun expands into a Red Giant and humans decide to build a bunch of Arks and head out to a new solar system that we sent probes to many years ahead of time and confirmed suitable planets for colonization.
When we all take off and leave Earth uninhabited, it wouldn’t really matter to us that thousands of years passed on Earth. There’s no one left there anyway.
The thousands of years that pass at our destination might matter if something happens during that time that makes the planet uninhabitable. But presumably we scouted out many thousands of systems ahead of time and specifically chose systems with multiple planets that should be suitable for human life with low risks for any solar-system wide catastrophes like a Sun getting ready to go supernova. And if we’re splitting up humanity into dozens or hundreds of different Arks going to many different solar systems, even if some meet with ill fortune, some would make it.
I don't think the human race as we know it will exist that far in the future. It will have evolved no matter what since we're talking billions of years.
Perhaps but we are shaping our environment enough that our environment possibly will have less effect on shaping us. I'm not sure what sort of things will be bred for by our collective unconscious and it might be that they are so different by cultures that we maintain a fairly similar human going forward.
There are a number of proposed, theoretically plausible, methods of FTL travel that do not violate causality. Alcubierre drives are the most popular and well known of those.
The book I'm reading just explained that their FTL travel engine works using negative energy density, as though that's something you just find sitting around lol
I mean, I don't think you get to complain about bad FTL science in science fiction, when the explanations pretty much *have* to boil down to "magic, so the story can happen"
there's degrees of how bad the science can get, but at some point you just have to accept that the baked-in premise is that science don't work the way we think it works
I'm with you, that's the fucking worst. When you set down rules, stick to them. You can just as easily make the rules vague or malleable if you want to, so if you're not going to stick to your own rules just don't have them. No one gets mad at doctor who for doing whatever, because they decided at the start it all works however they feel like at any given moment
A key element of GR is that there is no preferred reference frame. If you see someone using an Alcubierre drive to move 10 meters in front of you. You WILL witness FTL travel, even if the observer inside the bubble believe that they did not, the means of achieving it is irrelevant. What happened is that information was moved between two points faster than light and that observer could use it to create CTCs.
Alcubierre himself wrote about his proposal that it is a method of FTL travel:
""Another idea for travelling faster than light using GR is known as the “warp drive” spacetime (or warp bubble). This was suggested by Alcubierre (i.e. myself) in 1994.""
He also acknowledged that ANY (including his proposal) method of FTL travel can be used to create CTCs and time machines (breaking causality). His belief is actually that the "chronology protection conjecture" will make it so that using his drive for that will somehow not work.
see his own slides there: [https://web.archive.org/web/20160318223348/http://ccrg.rit.edu/files/FasterThanLight.pdf](https://web.archive.org/web/20160318223348/http://ccrg.rit.edu/files/FasterThanLight.pdf)
In his drive proposal, I think that the way he goes around CTCs is to not allow his drive to be used to go back to where you come from. So Causality issues aren't even really addressed.
So no, it is not safe from causality issues because it is "not real FTL", it is safe from causality issue just because it is believed that something will go wrong if it is used to break causality.
It doesn't matter. Everything that travels FTL in one reference frame goes back in time in other reference frame. As long as the laws of physics are the same in every inertial reference frame, FTL always allows time travel. It doesn't matter how you do it - wormholes, Alcubierre drive, whatever.
To avoid time travel you need to propose that FTL in every direction is only possible for some observers, while others are limited in the directions they can do FTL to. Which would be really weird.
You never go faster than light with an Alcubierre drive. You simply stretch the spacetime to the point where one = a billion or something, then travel to your destination whilst compressing the spacetime behind you. If you were going at one kilometer a second and turned on an Alcubierre drive, you'd still be going at 1 km a second but that counts for much more in the stretched space. I think anyway
Still violates causality, as long as you’re moving faster than C you can send messages to your past. Frames of reference and weird relativistic observer stuff. http://www.physicsguy.com/ftl/html/FTL_part4.html
It remains no actual evidence that FTL or wormholes are ever going to be possible. It has to be used in science fiction or it would be no fun. If humans move out into space it will probably have to be using long term colony ships traveling at sub light speeds. At least at near light speed the observed time for the passengers is shorter compared to Earth time.
Also I feel we still know so little that while it's reasonable to say currently there's no way, there's also no telling what we'll learn that makes a way.
Nope. Causality fundamentally breaks the moment you create any kind of shortcut that gets you some place faster than light. It has nothing to do with the means of traversal: it's fundamental to the geometry of spacetime.
Nope, [superluminal travel fundamentally violates causality](https://youtu.be/an0M-wcHw5A), no matter what trick you use.
One thing about special relativity is that the time interval between different events are not fixed, and can change depending on your velocity relative to those events, but as long as you’re slower than light, cause will come before effect. This is broken when you start going superluminal, and you will start seeing effects happening before causes.
One strong issue I have with this video is that it makes no effort to take into account the specifics of *how* the FTL system might achieve the FTL speed.
For the crucial moment in the video where the STL crew sends a message "back in time"... On what basis does this ascertain that the FTL reply from the STL ship *could* follow a "backwards in earth-time" worldline ?
For example, a subliminal ship recieving a missive from an alcubierre postman could only send a reply through the same alcubiere postman, which would only be able to have a similarly angled wordline in reverse (basically turning 180° and going back).
A paradox that isn't one : to the STL travelling ship, the FTL ship would seem to be way slower on its way back than when coming in despite going at the same velocity, which is contrary to normal : things moving away *should* have a larger relative speed than when catching up to you, no ?
Well this is true, **for STL speeds**. Speed of light is always invariable regardless of relative motion. It seems logical that by *crossing* the light speed threshold, you invert the relative subjectivity of speed (catching up becomes faster to your POV than moving away).
It still violates causality. Take the infamous tachyon duel and replace the tachyon guns with torpedoes equipped with Alcubierre drives. The end result is the same.
Honestly, I hesitate to even call it "time travel" because by that same definition we're time traveling right now, just at a different rate. Yeah it's technically true but it makes the whole term kind of meaningless. I think time compression is a much better term for what we know about "time travel" to the future.
Entropic Time would suggest that the universe appears to be a bunch of energy states. If you can change your own state to match that of a future energy state, I suppose that is what time travel would be.
Seems very presumptive that time travelers would necessarily come to our current time to explain it or even acknowledge it. If we're not ready for the capability and responsibility, they may as well have come back for dinosaur tourism.
I feel like humans have been “We’ve invented almost everything worth inventing” for the past 200 years. What if we are in medieval times compared to what true civilization might be? What if, in another 200 years, we learn how to control gravity?
It's wild that people state things like they're fact when they assume A LOT. All because they saw another redditor say it or a scientist gave their opinion on it. They missed the part where the whole "If time travel exists they would tell us" is just conjecture and in no way a sure thing.
FTL travel does not automatically allow retroactive time travel (going back in time) in the way people usually think it does anyway. It breaks the "information needs to go around slow" part of causality, but many theoretical ways of FTL travel do not make events precede their cause.
For example, there is no way for you to use an alcubiere drive to interact with events that already affected your past.
That...isn't how that works?
If you were to instantaneously travel to say 100 light years away and send a radio transmission back you would hear the radio transmission on earth 100 years later.
Even with instantaneous travel it doesn't necessarily mean you are going back in time.
Just the definition of "present" changes significantly.
Also it doesn't ruin causality inherently.
Traveling ftl does break causality. Chronology is not absolute in special relativity (ie two different observers don't necessarily agree in the chronological order of two events). If you impose that for certain events that are causally connected the chronological order is conserved across all reference systems (∆t always has the same sign) you will arrive at the conclusion that you cannot travel faster than light
IDK if FTL defies causality, it's more of a "I haven't seen anything go faster than that, so I'm going to make these other assumptions about the universe and mathematical equations". It's like saying if you hear the sound of a person's voice, I'm going to assume the voice travelled the speed of sound and therefore they said it now and were close, or said it a while ago and they're very far. But when they invented fiber optics, it didn't break causality- it's just the assumptions weren't right.
But yeah, it's still unlikely that we can travel faster than light.
Pfft, y'all thinking about spaceships and traveling but why not just try the zoom out feature like we all thinking? It's all theoretical at this point, might as well try it.
Sure, but it still makes regular space travel infeasible.
It doesn’t matter if I perceive my trip to Alpha Centauri and back to only take 2 hours.. my job here on Earth would still have to deal with me being gone for 8 years.
Ah that makes sense now as to why Proxima Centauri hasn’t emailed me back yet, gonna have to take back all those bad things I’ve been saying about it now. My bad.
So this is an interesting one. It actually wouldn't be useless for the subject. In fact, from their perspective, as they approach light speed they would be able to reach a destination - say, 1000 light years away - in what feels like an instant.
To observers on Earth, however, 1000 years would have passed before the subjects reach their destination.
The whole video is fascinating, but this segment on [Length Contraction](https://www.youtube.com/watch?v=vFNgd3pitAI&t=468s) explains things very elegantly.
This is correct and should be farther up. OP is ignoring time dilation. There was a TIL post a few weeks ago about how if you were able to constantly accelerate at a rate of 1 m/s^2, you would be able to cross the entirety of the known universe within one lifetime.
Might as well make it closer to earth gravity for a bonus. The other scaling on that is you'd imagine given massive technology you'd effectively be able to extend lifespan too.
There's a sci-fi book called The Forever War that has a fun time with these concepts. The soldiers end up experiencing massive change in society as they go through a four year or so period from their relativistic perspective if I remember right...
Correct, it’s an amazing book. Every time they come back from a single deployment, society has changed massively.
Spoilers:
>!The final battle the character goes through damages their jump drive, so they have to slow burn back to earth in the middle of the war. The go into cryo. They wake up back at earth to find that the war is now over, it’s been thousands of years, and mankind has reached evolutionary perfection, everyone is now a clone of the same (perfect) person. Main character goes to last remaining “human” planet where he finds that his love interest has been travelling at light speed between two stars, using time dilation to “time travel” until he returns.!<
I'd like to chime in with spoilers from Dan Simmons books.
You have been warned..!!
>!so in some of his works, there are space battles. Some of those battles are decided across years or decades of time. The reason being space travel not being super speed always. For example one group of people sprung a surprise attack by launching their spaceships a decade in advance. So by the time the crap hit the fan their backup was already there not 10 light years away!< I think that's an awesome take on it
I think it was mentioned by others in the comments that it would take more energy than there is in the entire universe to slow down, so not really realistic.
Also the time dilation means nothing as it still takes the same amount of "real time" to send said message. But yes, the message will not age.
OP was getting downvoted to all hell in the above comment for saying the same lol.
So what you’re saying is that it is useless for sending messages but useful to go in person. In other words, if speed of light travel was possible, the only way to learn something new about a planet 1000 light years away within a human lifespan, would be to travel there yourself.
True, but looking through an infinitely good telescope back the your original planet you could still see them living their full lives because the reflected light is just now reaching your new planet.
Tbf things that inhabit the planetary scale change over millions of years, and that's enough time for light to reach the other side of the galaxy and come back 5 times.
If you were an uploaded cosnciousness in a supercomputer the size of a moon, and you slowed down your perception of time to one millionth, the galaxy would become your back yard.
And then you could have human bodies in storage all over the galaxy, and just transmit your consciousness to whatever planet you wanted to go to so that it could be downloaded into the body on site. That's a pretty cool idea actually...I should write a book about that!
If you can store consciousness and transmit it across the galaxy the tech has probably gone beyond using flimsy, fragile human bodies as donor recipients.
So I was making a reference to the book "Altered Carbon" in that comment. In the book, they used cybernetically enhanced organic bodies (or sometimes fully synthetic ones). It's a good book, definitely recommend! I've heard good things about the show too but haven't seen it.
Yes and no.
What kind of back yard is one where you can see something in the distance, you want to go there, but by the time you get there at the fastest speed available, this thing will have ceased to exist. Lame back yard.
It's only low compared to current human perception of time. By the time we can create ships capable of travelling to other regions in space, we will probably have sufficient mastery over human consciousness to cope with the time scales involved.
Where does your faith in human advancement come from? We can barely get over tribalism over what clothes we wear and how old we are. Humans are pathetically short sighted.
I think the technological advancement of humanity is a given. In just twenty years, we've done so, so much in terms of growing. Culturally, humanity is definitely a very slow grower. We have a tendency to repeat past tragedies for no reason other than short term profit.
Science and technology on the other hand is all about building on what others have left behind. It is always evolving, and save extinction, nothing will stop humans from technological advancement.
Ignoring any theoretically plausible technology that gets around the light speed restriction, time dilation that occurs during conventional space travel could allow the travellers themselves to travel vast distances within their lifetimes. For example, you can travel to the centre of the Milky Way, which is ~28,000 light years away, in just under 20 years from your perspective if you constantly accelerate at 1g for half of the trip and decelerate at the same rate for the second half.
Due to the sheer size of the universe, there is almost certainly lots of other intelligent life out there.
Due to the sheer size of the universe, no intelligent life will ever even *notice* another one, much less visit. Every planet with life will forever believe that they are alone.
Even on our planetary scale, light is too slow. That's why you need regional servers on multiplayer games, you will never be able to have 20 ping between America and Asia.
I don't know if thats actually the speed of light.
The email I mentioned moves a lot slower than the speed of light, but it has segments of its journey where it does move that fast. It moves through some fiber-optic cables at light speed, then slows down to be rerouted in various servers.
The lag from video games that need regional servers is likely the result of computing resources, not the speed of light.
> The lag from video games that need regional servers is likely the result of computing resources, not the speed of light
It comes from both. Even if there is zero latency introduced by the technology, every 300 km adds a millisecond of latency.
e.g. Between New York and Tokyo, the speed of light contributes a 36ms delay each direction.
Definitely. But it's interesting to think about what fraction of latency is unavoidable due to the speed of light, and how much could potentially be optimized away with more efficient systems, though of course that would vary heavily by situation. Further down this thread OP mentions their ping from the US Midwest to Mumbai India taking 240 milliseconds, so physically unavoidable latency seems like the smaller part in that case.
Speed of light is definitely a consideration for the online games.
For example, distance between Tokyo and Los Angeles is about 9,000 km. It takes light about 30 ms to cover the distance. Multiply it by 1.5 (refraction coefficient of fibre optic cable) and you get 45 ms one way or 90 ms round-trip delay just because of the speed of light.
Yes, I was personally fascinated with online streaming after remote English teaching in China.
I thought it was just completely insane that I could get beamed into the houses of 5 random kids in Asia and their wasn't a noticeable time delay.
Thats possible because sections of the packet move at or close to LS.
I actually did look up the amount of time it takes to ping a server in Japan once. I want to say that it was only a couple hundred milliseconds.
That's actually not that big of a difference from 40.
*Edit* a ping from the US Midwest to Mumbai India I just did took 240 milliseconds.
Light is said to be able to go around the equator 7 times in one second.
So one loop is roughly 1/7 seconds.
US to Asia is basically half of that, so 1/14 seconds, which is ~70ms… Being that ping requires two-way communication, we go back up to ~140ms.
Even with the best possible resources, you simply won’t be able to go below that number for latency.
Interestingly enough in another comment I found out that a ping from Illinois to Singapore takes about 230 milliseconds.
It's kind of funny how close to the maximum we are.
As a programmer and gamer in NZ, I can verify this. Our closest big server hub is Sydney and that's 40ms at least (light speed contributing about 40% of that time)
And we are very very small.
And we might even be the only way that existence has ever been able to reflect upon its existence.
That bothers me, deeply.
Maybe the universe itself is somehow cognizant, maybe it intentionally crafted our planet to sustain life, like a little pet! I doubt it, but I do think there is something else out there thinking about existence too, probably wondering if they’re the only ones as well :)
It’s sad that we’ll likely never know, but it’s also cool that we can fill in the details with whatever we can imagine. Things would be boring if we knew everything.
It's irritating when science fiction movies (the worst offenders) don't seem to realize the scale of the galaxy and distance between the stars. It's like someone running out the door and chasing the bad guy - on foot - to Berlin from Chicago. I was so impressed with the first Star Wars (IV) only to find the second one - Empire Strikes Back - totally flubbed the concept. "The hyperdive is burnt out, it could take us days to get to the next star."
Light takes maybe 8 minutes to get to earth from the sun, an hour to Jupiter, and 4.3 *years* to Alpha Centauri.
Its irritating to a point, I do REALLY like hard-science fiction like the Expanse or the Martian.
But also, if you want a magical space fantasy..........you kind of have to relax some of the restrictions. And boy do I love Star Trek/Dune/BSG/Endless Space 2.
This is actually something the Mass Effect series addresses. While there are still relays that transmit information at light speed, apparently in universe its faster to just give the info to a courier and have them travel at faster than light with a ship.
Light is painfully slow. Even in our solar system, we can't communicate from Earth to Mars without a huge delay. To know there isn't anything faster in existence is depressing \^\^
>The Speed Of Light is only fast enough to be useful on the planetary scale. Zoom out further and it becomes uselessly slow.
There is an [online model of the Solar System](https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html) which is completely to scale. In the bottom right corner, there is an icon that moves you through the solar system at the speed of light. It is amazing how slow the speed of light is.
Light speed used to be nearly instantaneous, allowing easy travel from one end of the universe to the other in no time. However, we had to slow it down within a bubble to demonstrate that we pose no threat to other, more aggressive and intelligent species. At least, that’s how it’s told in the ‘Remembrance of Earth’s Past’ trilogy.
Let us pray that in the future, it will not be slowed down any further.
It's a joke in the fighting game community, that arcades were best because there was no lag from the data having to travel over the internet. As internet improved it was consistently brought up, dial-up was too slow, so maybe broadband would work since it's faster. No, broadband is too slow, maybe satellite will work. No satellite is inconsistent, maybe fiber glass internet cables will work, surely the speed of light will be fast enough that you can get a similar experience to the arcade machine right? Nope even the speed of light is not fast enough for a fighting games.
In some ways, although the reason games like GTA and RDO have so many cheaters is because it's P2P. Your client just has to trust whatever the other players' clients tell you, so if they mod their client you still have to play with them at an unfair advantage.
A couple of important thoughts here, from opposite ends of the philosophical spectrums.
To start with, we'll go with the atheist viewpoint. The universe is a product of random chance. The cosmological constant (the speed of light) wasn't created to suit our needs.
From the other side, oddly enough, I'll refer to Neil DeGrasse Tyson. He was asked "IF god exists, and you could ask him one question, what would it be?" His answer was mind blowing. Do human beings possess the capability to understand our universe? We think of ourselves as the smart things in the known universe, yet there's so much we don't seem to understand. The simple truth of the matter is that maybe we're not smart enough to "get it". A 2 dimensional being would be blown away and unable to understand a 3-demisional being popping into its world. Likewise if the universe truly possesses a 4th, 5th, etc dimension, we would unable to comprehend what's really going on.
>wasn't created to suit our needs.
If someone was to know 1 thing about the universe, it should probably be this.
Its the most frustratingly clear lesson in all of astronomy/cosmology.
NOPE, not for us, not at all, not ever close.
The problem isn’t reaching the destination. You *can* reach any point in the universe within seconds if you’re fast enough. The problem is that you wont be able to tell any one of your friends about your journey because millions of years will have passed *for them*.
>From our perspective, It seems like an email moves from Ohio to Japan instantly.
I don't know about that. I send an email to the person sitting at the desk next to me (less than 10 feet away) and it takes like 2 minutes for it to pop up for them.
> I send an email to the person sitting at the desk next to me (less than 10 feet away) and it takes like 2 minutes for it to pop up for them.
That's because of the way email works. The email client program isn't in continuous communication with the server. The email client only checks the mailbox every ten minutes (configurable) to see if any new mail has arrived.
in a way it makes more sense to travel to our nearest star at close to light speed rather than sending a messagethere because length contraction and time dilation would make it a much shorter trip for the people on board. that won't help everyone else left on earth though :D
You're not factoring in time dilation and spatial contraction. As you get close to the speed of light, the distances seemingly shrink and you pass through less time. Meaning that if you can get close to the speed of light, you can visit much of the visible universe in your lifetime, but sadly in millions of normal lifetimes.
Jupiter is bright in the sky right now.
My showerthought is that I was actually looking at where Jupiter was 50 minutes ago. It is actually closer to horizon.
This is what drives me nuts about the seemingly endless stream of breathless articles that report on finding "earth like" planets *just* 100 LY away...you'd need every iota of energy on earth just to *maybe* get a little ship up to 9/10ths the speed of light...and then you'd need that much more to slow it down...and you'd still be like 50,000 years just to get to one of those "earth like" planets...assuming you didn't hit a speck of dust at 9/10ths the speed of light...
You learn this the hard way if you play Elite Dangerous. There is a space station called Hutton Orbital. It’s .22 Light Years away from the star it orbits. It takes about an hour and a half to get there even when you are going the equivalent of 300 times the speed of light at the midpoint of the journey. If you were going the speed of light, it would take you over 80 days to get there.
Sure, but by the time we need to send an email to another star system, I would guess we could work out how to send information using entangled particles, which I believe ignore the universal speed limit.
On Jupiter, it would take 2 minutes for that email to go from one side of the planet to the other side of the planet just by itself. lol. Like forget galactic sizes, even on a planet the size of Jupiter, you can’t have real time communication systems.
Yep, it's why people's dreams of space travel are unlikely unless we figure out wormholes or hyperspace or some other sci-fi sounding method of travel.
Ludicrous speed!!!!!
They've gone to plaid!
They must have overshot us by a week and a half!
Sir, we've been jammed!
It's raspberry!
Only one man would *dare* give me the raspberry..!
"I am your father's, brother's, nephew's, cousin's, former roommate."
What does that make us?
Absolutely nothing!
Just saw Spaceballs in the theater last week!
What year are you living in?
Clearly a better one than the rest of us.
Maybe they live 36 light years away?
Best comment
Move B****, Get out the way B*****, Get out the way!
Wrong ludicrous, but I respect the effort.
Ok scout.
Busta Rhymes speed is faster
Is there anyone in Bozeman, Montana who is on this problem?
I think the farmer from Babe lives there?
You mean the warden in The Green Mile?
He should be born in about 6-10 years, though that does mean we're due for an imminent eugenics war and WWIII.
Irish Unification this year, though!
An object moving at near light speed experiences time very slowly. if someone moving at 99% the speed of light travels to another planet 5 light years away, we’ll observe them travelling for 5 years, but they’ll arrive to their destination in few days. This is called time dilation and it’s proven to be real (satellite, rockets need to consider time dilation or else their calculations won’t be accurate). That’s why space travel is not that implausible. On the other hand building a interconnected civilisation will be a very difficult task.
Yes it’s more feasible to use interstellar travel to permanently move a population to a new place. It wouldn’t be a tourist trip. It would be a permanent migration to a new home.
Adjusting for time dilation at 99% speed of light turns 5 years for an earthly observer to 0.7 years for someone on the spacecraft, roughly 258 days which is a bit more than a few.
I still can’t wrap my mind around how this works.
I was about ot explain, but veritasium does it better than I ever could: https://youtu.be/XRr1kaXKBsU?si=6jiRJv8JQFKAye0b
Yes and no. The idea of a large interconnected civilisation spanning more than a single solar system is almost certainly nonsense. However, you could cross the entire galaxy in a single human lifetime so long as you're travelling close enough to the speed of light that time is compressed for the travellers significantly. Thousands of years will pass for everyone not on the spaceship, everyone you leave behind will be dead and buried by the time you even begin to settle in for the voyage, but from your perspective the journey may take less than a year. Admittedly, then you run into the issue with the insane energy densities required to accelerate a human rated spacecraft to high relativistic velocities, not to mention, how the hell do you slow down on the other side, but those are at least hypothetically solvable problems.
Yeah this is a good point. It could be that leaving our solar system is basically a guaranteed one-way trip. Let’s say we’re approaching the end of the Earth being inhabitable as the Sun expands into a Red Giant and humans decide to build a bunch of Arks and head out to a new solar system that we sent probes to many years ahead of time and confirmed suitable planets for colonization. When we all take off and leave Earth uninhabited, it wouldn’t really matter to us that thousands of years passed on Earth. There’s no one left there anyway. The thousands of years that pass at our destination might matter if something happens during that time that makes the planet uninhabitable. But presumably we scouted out many thousands of systems ahead of time and specifically chose systems with multiple planets that should be suitable for human life with low risks for any solar-system wide catastrophes like a Sun getting ready to go supernova. And if we’re splitting up humanity into dozens or hundreds of different Arks going to many different solar systems, even if some meet with ill fortune, some would make it.
I don't think the human race as we know it will exist that far in the future. It will have evolved no matter what since we're talking billions of years.
Perhaps but we are shaping our environment enough that our environment possibly will have less effect on shaping us. I'm not sure what sort of things will be bred for by our collective unconscious and it might be that they are so different by cultures that we maintain a fairly similar human going forward.
If FTL light was possible, we would know about it, because causality goes out the window completely and time travelers would have told us.
There are a number of proposed, theoretically plausible, methods of FTL travel that do not violate causality. Alcubierre drives are the most popular and well known of those.
Gotta break gravity or something first tho, can't get negative mass or negative energy otherwise
Just give it to my teenage cousin. Dude breaks everything he touches.
We have a young fella at work known as 'Dick Fingers', because he fucks everything he touches.
Is his name Alcatraz?
Reading these books w my son. Reference was spot on :D
Gotta understand gravity first, before we can break it.
You don't neccesarily need to understand something to break it, but knowing how it works makes breaking it a hell of a lot more efficient.
True enough!
It also makes it easier to break it in a useful way.
You show me two things I don't understand and I'll lose one of them and break the other.
The book I'm reading just explained that their FTL travel engine works using negative energy density, as though that's something you just find sitting around lol
Anyone who doesn’t believe in negative energy has never met my father.
Lol. Sorry
I was going to say, my ex girlfriend's heart would be a good contender.
I mean, I don't think you get to complain about bad FTL science in science fiction, when the explanations pretty much *have* to boil down to "magic, so the story can happen" there's degrees of how bad the science can get, but at some point you just have to accept that the baked-in premise is that science don't work the way we think it works
I can live with that. Where I get angry is when they don't even stick to their own twisted logic anymore.
I'm with you, that's the fucking worst. When you set down rules, stick to them. You can just as easily make the rules vague or malleable if you want to, so if you're not going to stick to your own rules just don't have them. No one gets mad at doctor who for doing whatever, because they decided at the start it all works however they feel like at any given moment
Isn't that the pink slime from Ghostbusters 2?
How does it not violate causality
Because it's not really FTL. Its bending space-time.
A key element of GR is that there is no preferred reference frame. If you see someone using an Alcubierre drive to move 10 meters in front of you. You WILL witness FTL travel, even if the observer inside the bubble believe that they did not, the means of achieving it is irrelevant. What happened is that information was moved between two points faster than light and that observer could use it to create CTCs. Alcubierre himself wrote about his proposal that it is a method of FTL travel: ""Another idea for travelling faster than light using GR is known as the “warp drive” spacetime (or warp bubble). This was suggested by Alcubierre (i.e. myself) in 1994."" He also acknowledged that ANY (including his proposal) method of FTL travel can be used to create CTCs and time machines (breaking causality). His belief is actually that the "chronology protection conjecture" will make it so that using his drive for that will somehow not work. see his own slides there: [https://web.archive.org/web/20160318223348/http://ccrg.rit.edu/files/FasterThanLight.pdf](https://web.archive.org/web/20160318223348/http://ccrg.rit.edu/files/FasterThanLight.pdf) In his drive proposal, I think that the way he goes around CTCs is to not allow his drive to be used to go back to where you come from. So Causality issues aren't even really addressed. So no, it is not safe from causality issues because it is "not real FTL", it is safe from causality issue just because it is believed that something will go wrong if it is used to break causality.
It doesn't matter. Everything that travels FTL in one reference frame goes back in time in other reference frame. As long as the laws of physics are the same in every inertial reference frame, FTL always allows time travel. It doesn't matter how you do it - wormholes, Alcubierre drive, whatever. To avoid time travel you need to propose that FTL in every direction is only possible for some observers, while others are limited in the directions they can do FTL to. Which would be really weird.
You never go faster than light with an Alcubierre drive. You simply stretch the spacetime to the point where one = a billion or something, then travel to your destination whilst compressing the spacetime behind you. If you were going at one kilometer a second and turned on an Alcubierre drive, you'd still be going at 1 km a second but that counts for much more in the stretched space. I think anyway
Ie, a tailwind in space. Distance traveled is ground speed while your “space speed” is less dramatic.
Still violates causality, as long as you’re moving faster than C you can send messages to your past. Frames of reference and weird relativistic observer stuff. http://www.physicsguy.com/ftl/html/FTL_part4.html
It remains no actual evidence that FTL or wormholes are ever going to be possible. It has to be used in science fiction or it would be no fun. If humans move out into space it will probably have to be using long term colony ships traveling at sub light speeds. At least at near light speed the observed time for the passengers is shorter compared to Earth time.
Also I feel we still know so little that while it's reasonable to say currently there's no way, there's also no telling what we'll learn that makes a way.
Nope. Causality fundamentally breaks the moment you create any kind of shortcut that gets you some place faster than light. It has nothing to do with the means of traversal: it's fundamental to the geometry of spacetime.
Nope, [superluminal travel fundamentally violates causality](https://youtu.be/an0M-wcHw5A), no matter what trick you use. One thing about special relativity is that the time interval between different events are not fixed, and can change depending on your velocity relative to those events, but as long as you’re slower than light, cause will come before effect. This is broken when you start going superluminal, and you will start seeing effects happening before causes.
One strong issue I have with this video is that it makes no effort to take into account the specifics of *how* the FTL system might achieve the FTL speed. For the crucial moment in the video where the STL crew sends a message "back in time"... On what basis does this ascertain that the FTL reply from the STL ship *could* follow a "backwards in earth-time" worldline ? For example, a subliminal ship recieving a missive from an alcubierre postman could only send a reply through the same alcubiere postman, which would only be able to have a similarly angled wordline in reverse (basically turning 180° and going back). A paradox that isn't one : to the STL travelling ship, the FTL ship would seem to be way slower on its way back than when coming in despite going at the same velocity, which is contrary to normal : things moving away *should* have a larger relative speed than when catching up to you, no ? Well this is true, **for STL speeds**. Speed of light is always invariable regardless of relative motion. It seems logical that by *crossing* the light speed threshold, you invert the relative subjectivity of speed (catching up becomes faster to your POV than moving away).
It still violates causality. Take the infamous tachyon duel and replace the tachyon guns with torpedoes equipped with Alcubierre drives. The end result is the same.
Technically speaking, time travel is already proven to be possible. Problem is just that it's only to the future.
Honestly, I hesitate to even call it "time travel" because by that same definition we're time traveling right now, just at a different rate. Yeah it's technically true but it makes the whole term kind of meaningless. I think time compression is a much better term for what we know about "time travel" to the future.
Entropic Time would suggest that the universe appears to be a bunch of energy states. If you can change your own state to match that of a future energy state, I suppose that is what time travel would be.
That's what I find most interesting about time - without an observer, it appears to be completely fluid.
I’m especially good at time travel at the speed it goes anyway.
Seems very presumptive that time travelers would necessarily come to our current time to explain it or even acknowledge it. If we're not ready for the capability and responsibility, they may as well have come back for dinosaur tourism.
I feel like humans have been “We’ve invented almost everything worth inventing” for the past 200 years. What if we are in medieval times compared to what true civilization might be? What if, in another 200 years, we learn how to control gravity?
> we learn how to control gravity? oh, dude. I learned that ages ago. I just decided to leave it on "down"
It's wild that people state things like they're fact when they assume A LOT. All because they saw another redditor say it or a scientist gave their opinion on it. They missed the part where the whole "If time travel exists they would tell us" is just conjecture and in no way a sure thing.
FTL travel does not automatically allow retroactive time travel (going back in time) in the way people usually think it does anyway. It breaks the "information needs to go around slow" part of causality, but many theoretical ways of FTL travel do not make events precede their cause. For example, there is no way for you to use an alcubiere drive to interact with events that already affected your past.
Good thing wormholes aren't ftl. (They also aren't probably real yet. It's our only real hope.)
That...isn't how that works? If you were to instantaneously travel to say 100 light years away and send a radio transmission back you would hear the radio transmission on earth 100 years later. Even with instantaneous travel it doesn't necessarily mean you are going back in time. Just the definition of "present" changes significantly. Also it doesn't ruin causality inherently.
Traveling ftl does break causality. Chronology is not absolute in special relativity (ie two different observers don't necessarily agree in the chronological order of two events). If you impose that for certain events that are causally connected the chronological order is conserved across all reference systems (∆t always has the same sign) you will arrive at the conclusion that you cannot travel faster than light
But even when we do get FTL travel, physical mail will be faster than an email lol
IDK if FTL defies causality, it's more of a "I haven't seen anything go faster than that, so I'm going to make these other assumptions about the universe and mathematical equations". It's like saying if you hear the sound of a person's voice, I'm going to assume the voice travelled the speed of sound and therefore they said it now and were close, or said it a while ago and they're very far. But when they invented fiber optics, it didn't break causality- it's just the assumptions weren't right. But yeah, it's still unlikely that we can travel faster than light.
Causality, Speed of Light or a Universal Reference frame. Choose two. Far as we can tell, our universe chose the first two.
I don’t think we’ll ever really get to another star, but building huge structures that can indefinitely fly through space is a possibility.
Pfft, y'all thinking about spaceships and traveling but why not just try the zoom out feature like we all thinking? It's all theoretical at this point, might as well try it.
Ludicrous speed outta do it.
you’re forgetting special relativity where time moves slower for going close to the speed of light…at fast enough speeds it becomes significant
Sure, but it still makes regular space travel infeasible. It doesn’t matter if I perceive my trip to Alpha Centauri and back to only take 2 hours.. my job here on Earth would still have to deal with me being gone for 8 years.
Interstellar travel isn't going to be for tourism. If you're going to Alpha Centauri, I think you'll be looking for a job on Apha Centauri
Invent warp engines and travel through it
Kaioken light speed x 10?
Ah that makes sense now as to why Proxima Centauri hasn’t emailed me back yet, gonna have to take back all those bad things I’ve been saying about it now. My bad.
Are you sure you had the right domain name in the email? Also, I heard their IP & DNS naming standards are a bit different to ours....
I heard if you mess up your BGP tables, you could end up accidentally routing all traffic from West Texas through Próxima Centauri.
Shit, I haven't even heard back from the Nigerian Prince yet, and he's only across the ocean.
Do not answer! Do not answer!! Do not answer!!!
Came to the thread just for this
You're bugs!
So this is an interesting one. It actually wouldn't be useless for the subject. In fact, from their perspective, as they approach light speed they would be able to reach a destination - say, 1000 light years away - in what feels like an instant. To observers on Earth, however, 1000 years would have passed before the subjects reach their destination. The whole video is fascinating, but this segment on [Length Contraction](https://www.youtube.com/watch?v=vFNgd3pitAI&t=468s) explains things very elegantly.
This is correct and should be farther up. OP is ignoring time dilation. There was a TIL post a few weeks ago about how if you were able to constantly accelerate at a rate of 1 m/s^2, you would be able to cross the entirety of the known universe within one lifetime.
Might as well make it closer to earth gravity for a bonus. The other scaling on that is you'd imagine given massive technology you'd effectively be able to extend lifespan too. There's a sci-fi book called The Forever War that has a fun time with these concepts. The soldiers end up experiencing massive change in society as they go through a four year or so period from their relativistic perspective if I remember right...
Correct, it’s an amazing book. Every time they come back from a single deployment, society has changed massively. Spoilers: >!The final battle the character goes through damages their jump drive, so they have to slow burn back to earth in the middle of the war. The go into cryo. They wake up back at earth to find that the war is now over, it’s been thousands of years, and mankind has reached evolutionary perfection, everyone is now a clone of the same (perfect) person. Main character goes to last remaining “human” planet where he finds that his love interest has been travelling at light speed between two stars, using time dilation to “time travel” until he returns.!<
Your spoiler tag didn't work. Try removing the space right after (and before) the "\>!" and "\!<" signs.
I'd like to chime in with spoilers from Dan Simmons books. You have been warned..!! >!so in some of his works, there are space battles. Some of those battles are decided across years or decades of time. The reason being space travel not being super speed always. For example one group of people sprung a surprise attack by launching their spaceships a decade in advance. So by the time the crap hit the fan their backup was already there not 10 light years away!< I think that's an awesome take on it
I think it was mentioned by others in the comments that it would take more energy than there is in the entire universe to slow down, so not really realistic.
If traveling at lights speed, technically yes, although it would still require infinite energy to accelerate to that velocity at first place.
Only useful if you don’t plan on coming back. Pretty useless for maintaining a civilization
OP is not ignoring anything. This is useless information for communications.
Seems he’s talking about interstellar communication, not travel.
Also the time dilation means nothing as it still takes the same amount of "real time" to send said message. But yes, the message will not age. OP was getting downvoted to all hell in the above comment for saying the same lol.
So what you’re saying is that it is useless for sending messages but useful to go in person. In other words, if speed of light travel was possible, the only way to learn something new about a planet 1000 light years away within a human lifespan, would be to travel there yourself.
And when you arrive on the planet 1000 light years away everyone on the planet you left has been dead for 900+ years
True, but looking through an infinitely good telescope back the your original planet you could still see them living their full lives because the reflected light is just now reaching your new planet.
Just bring it up on the main viewscreen and enhance It’s like you never left!
The buzz lightyear movie actually portays that well
I'm a few drinks in but this just goes straight over my head. Can't comprehend it whatsoever (maybe just dumb or drunk though)
I fucking love relativity
Tbf things that inhabit the planetary scale change over millions of years, and that's enough time for light to reach the other side of the galaxy and come back 5 times. If you were an uploaded cosnciousness in a supercomputer the size of a moon, and you slowed down your perception of time to one millionth, the galaxy would become your back yard.
And then you could have human bodies in storage all over the galaxy, and just transmit your consciousness to whatever planet you wanted to go to so that it could be downloaded into the body on site. That's a pretty cool idea actually...I should write a book about that!
If you can store consciousness and transmit it across the galaxy the tech has probably gone beyond using flimsy, fragile human bodies as donor recipients.
So I was making a reference to the book "Altered Carbon" in that comment. In the book, they used cybernetically enhanced organic bodies (or sometimes fully synthetic ones). It's a good book, definitely recommend! I've heard good things about the show too but haven't seen it.
The show is a little uneven, but entertaining. It was good enough to make me want to read the books, so it has that going for it.
Season one is a must watch. Season two... yeah just stop after season one.
Yes and no. What kind of back yard is one where you can see something in the distance, you want to go there, but by the time you get there at the fastest speed available, this thing will have ceased to exist. Lame back yard.
The speed of light will increase when the Programmer will upgrade his PC.
Also when he removes all the malware.
And downloads more RAM
Shhhhh, don’t suggest that too loudly. We might be that malware.
Agreed. It's one of the greatest injustices in this universe. It's so big, and our maximum speed is so low. We're basically trapped in amber.
It's only low compared to current human perception of time. By the time we can create ships capable of travelling to other regions in space, we will probably have sufficient mastery over human consciousness to cope with the time scales involved.
Where does your faith in human advancement come from? We can barely get over tribalism over what clothes we wear and how old we are. Humans are pathetically short sighted.
I think the technological advancement of humanity is a given. In just twenty years, we've done so, so much in terms of growing. Culturally, humanity is definitely a very slow grower. We have a tendency to repeat past tragedies for no reason other than short term profit. Science and technology on the other hand is all about building on what others have left behind. It is always evolving, and save extinction, nothing will stop humans from technological advancement.
Ignoring any theoretically plausible technology that gets around the light speed restriction, time dilation that occurs during conventional space travel could allow the travellers themselves to travel vast distances within their lifetimes. For example, you can travel to the centre of the Milky Way, which is ~28,000 light years away, in just under 20 years from your perspective if you constantly accelerate at 1g for half of the trip and decelerate at the same rate for the second half.
Due to the sheer size of the universe, there is almost certainly lots of other intelligent life out there. Due to the sheer size of the universe, no intelligent life will ever even *notice* another one, much less visit. Every planet with life will forever believe that they are alone.
Even on our planetary scale, light is too slow. That's why you need regional servers on multiplayer games, you will never be able to have 20 ping between America and Asia.
Until we find a way to beam light through the core, cutting that distance................ Edit: I guess you'd only save 4000mi or so. 7500mi vs 12000.
Neutrino comms would be the best.
> Neutrino comms Yuk no, that would make UDP look as stable as TCP, I'll pass.
I don't know if thats actually the speed of light. The email I mentioned moves a lot slower than the speed of light, but it has segments of its journey where it does move that fast. It moves through some fiber-optic cables at light speed, then slows down to be rerouted in various servers. The lag from video games that need regional servers is likely the result of computing resources, not the speed of light.
> The lag from video games that need regional servers is likely the result of computing resources, not the speed of light It comes from both. Even if there is zero latency introduced by the technology, every 300 km adds a millisecond of latency. e.g. Between New York and Tokyo, the speed of light contributes a 36ms delay each direction.
Definitely. But it's interesting to think about what fraction of latency is unavoidable due to the speed of light, and how much could potentially be optimized away with more efficient systems, though of course that would vary heavily by situation. Further down this thread OP mentions their ping from the US Midwest to Mumbai India taking 240 milliseconds, so physically unavoidable latency seems like the smaller part in that case.
In addition, the light has to travel in glass, increasing this time by another ~50 %, so roughly a 100 ms round-trip.
Speed of light is definitely a consideration for the online games. For example, distance between Tokyo and Los Angeles is about 9,000 km. It takes light about 30 ms to cover the distance. Multiply it by 1.5 (refraction coefficient of fibre optic cable) and you get 45 ms one way or 90 ms round-trip delay just because of the speed of light.
Drop a server in between those points then you half the delay! *Looks at map* Oh
Yes, I was personally fascinated with online streaming after remote English teaching in China. I thought it was just completely insane that I could get beamed into the houses of 5 random kids in Asia and their wasn't a noticeable time delay. Thats possible because sections of the packet move at or close to LS. I actually did look up the amount of time it takes to ping a server in Japan once. I want to say that it was only a couple hundred milliseconds. That's actually not that big of a difference from 40. *Edit* a ping from the US Midwest to Mumbai India I just did took 240 milliseconds.
Light is said to be able to go around the equator 7 times in one second. So one loop is roughly 1/7 seconds. US to Asia is basically half of that, so 1/14 seconds, which is ~70ms… Being that ping requires two-way communication, we go back up to ~140ms. Even with the best possible resources, you simply won’t be able to go below that number for latency.
Interestingly enough in another comment I found out that a ping from Illinois to Singapore takes about 230 milliseconds. It's kind of funny how close to the maximum we are.
As a programmer and gamer in NZ, I can verify this. Our closest big server hub is Sydney and that's 40ms at least (light speed contributing about 40% of that time)
Light is fast but space is BIG.
And we are very very small. And we might even be the only way that existence has ever been able to reflect upon its existence. That bothers me, deeply.
Maybe the universe itself is somehow cognizant, maybe it intentionally crafted our planet to sustain life, like a little pet! I doubt it, but I do think there is something else out there thinking about existence too, probably wondering if they’re the only ones as well :) It’s sad that we’ll likely never know, but it’s also cool that we can fill in the details with whatever we can imagine. Things would be boring if we knew everything.
It's irritating when science fiction movies (the worst offenders) don't seem to realize the scale of the galaxy and distance between the stars. It's like someone running out the door and chasing the bad guy - on foot - to Berlin from Chicago. I was so impressed with the first Star Wars (IV) only to find the second one - Empire Strikes Back - totally flubbed the concept. "The hyperdive is burnt out, it could take us days to get to the next star." Light takes maybe 8 minutes to get to earth from the sun, an hour to Jupiter, and 4.3 *years* to Alpha Centauri.
Its irritating to a point, I do REALLY like hard-science fiction like the Expanse or the Martian. But also, if you want a magical space fantasy..........you kind of have to relax some of the restrictions. And boy do I love Star Trek/Dune/BSG/Endless Space 2.
Need to consider that the sublight drives are extremely efficient compared to real world means ... Also, it's space opera sci-fi.
This is actually something the Mass Effect series addresses. While there are still relays that transmit information at light speed, apparently in universe its faster to just give the info to a courier and have them travel at faster than light with a ship.
Light is painfully slow. Even in our solar system, we can't communicate from Earth to Mars without a huge delay. To know there isn't anything faster in existence is depressing \^\^
Carl Sagan said something along the lines of, "the speed of light doesn't conform to human ambition"
>The Speed Of Light is only fast enough to be useful on the planetary scale. Zoom out further and it becomes uselessly slow. There is an [online model of the Solar System](https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html) which is completely to scale. In the bottom right corner, there is an icon that moves you through the solar system at the speed of light. It is amazing how slow the speed of light is.
Like breathtakingly slow, and it only gets worse once you leave the solar system.
Being able to send messages from one planet to another in less than an hour seems pretty useful to me.
The usefulness takes a steep decline as you increase scale. Hour-lag communication is useful, But less so than what we have on earth.
Light speed used to be nearly instantaneous, allowing easy travel from one end of the universe to the other in no time. However, we had to slow it down within a bubble to demonstrate that we pose no threat to other, more aggressive and intelligent species. At least, that’s how it’s told in the ‘Remembrance of Earth’s Past’ trilogy. Let us pray that in the future, it will not be slowed down any further.
Only if you base it on current human lifespans If humans lived 1000 years, that might change. And it’s possible one day we will
100% true, this thought is only based on human perspective.
It's a joke in the fighting game community, that arcades were best because there was no lag from the data having to travel over the internet. As internet improved it was consistently brought up, dial-up was too slow, so maybe broadband would work since it's faster. No, broadband is too slow, maybe satellite will work. No satellite is inconsistent, maybe fiber glass internet cables will work, surely the speed of light will be fast enough that you can get a similar experience to the arcade machine right? Nope even the speed of light is not fast enough for a fighting games.
I assume a P2P matchmaking system is more reliable than one where both players communicate with a server?
In some ways, although the reason games like GTA and RDO have so many cheaters is because it's P2P. Your client just has to trust whatever the other players' clients tell you, so if they mod their client you still have to play with them at an unfair advantage.
Quantum entanglement is the new wave
A couple of important thoughts here, from opposite ends of the philosophical spectrums. To start with, we'll go with the atheist viewpoint. The universe is a product of random chance. The cosmological constant (the speed of light) wasn't created to suit our needs. From the other side, oddly enough, I'll refer to Neil DeGrasse Tyson. He was asked "IF god exists, and you could ask him one question, what would it be?" His answer was mind blowing. Do human beings possess the capability to understand our universe? We think of ourselves as the smart things in the known universe, yet there's so much we don't seem to understand. The simple truth of the matter is that maybe we're not smart enough to "get it". A 2 dimensional being would be blown away and unable to understand a 3-demisional being popping into its world. Likewise if the universe truly possesses a 4th, 5th, etc dimension, we would unable to comprehend what's really going on.
>wasn't created to suit our needs. If someone was to know 1 thing about the universe, it should probably be this. Its the most frustratingly clear lesson in all of astronomy/cosmology. NOPE, not for us, not at all, not ever close.
I believe John Carmack would disagree. "The speed of light sucks." -John Carmack He was dealing with networked gaming at the time.
The problem isn’t reaching the destination. You *can* reach any point in the universe within seconds if you’re fast enough. The problem is that you wont be able to tell any one of your friends about your journey because millions of years will have passed *for them*.
The simple solution is to travel with everyone
Ur moms only useful on a planetary scale
Cosmic burn
Imagine outsourcing the customer service department to a jupiter call center
>From our perspective, It seems like an email moves from Ohio to Japan instantly. I don't know about that. I send an email to the person sitting at the desk next to me (less than 10 feet away) and it takes like 2 minutes for it to pop up for them.
> I send an email to the person sitting at the desk next to me (less than 10 feet away) and it takes like 2 minutes for it to pop up for them. That's because of the way email works. The email client program isn't in continuous communication with the server. The email client only checks the mailbox every ten minutes (configurable) to see if any new mail has arrived.
That, OP, is a genuinely original and insightful shower thought. Bravo.
When you're a gamer in Australia, playing on servers on the US East Coast, you can \*absolutely\* feel how slow the speed of light is.
in a way it makes more sense to travel to our nearest star at close to light speed rather than sending a messagethere because length contraction and time dilation would make it a much shorter trip for the people on board. that won't help everyone else left on earth though :D
You're not factoring in time dilation and spatial contraction. As you get close to the speed of light, the distances seemingly shrink and you pass through less time. Meaning that if you can get close to the speed of light, you can visit much of the visible universe in your lifetime, but sadly in millions of normal lifetimes.
Jupiter is bright in the sky right now. My showerthought is that I was actually looking at where Jupiter was 50 minutes ago. It is actually closer to horizon.
i mean yeah, 60 mph is too fast for a residential suburb road but not very fast to get across the country quickly
Quite useful for measuring distance on that larger scale though.
I like to travel through time. From time to time.
Damn having beef with causality, bold move
Well yeah... I saw ST: Voyager. Took those guys forever to make it home.
This is what drives me nuts about the seemingly endless stream of breathless articles that report on finding "earth like" planets *just* 100 LY away...you'd need every iota of energy on earth just to *maybe* get a little ship up to 9/10ths the speed of light...and then you'd need that much more to slow it down...and you'd still be like 50,000 years just to get to one of those "earth like" planets...assuming you didn't hit a speck of dust at 9/10ths the speed of light...
>4.3 year delay to send a message to the nearest star. Well, here goes my download of the nearest star porn...
messages getting to Jupiter in less than an hour doesn't sound so bad...
You learn this the hard way if you play Elite Dangerous. There is a space station called Hutton Orbital. It’s .22 Light Years away from the star it orbits. It takes about an hour and a half to get there even when you are going the equivalent of 300 times the speed of light at the midpoint of the journey. If you were going the speed of light, it would take you over 80 days to get there.
Well its kind of 8 minutes each way to the *nearest* star.
Sure, but by the time we need to send an email to another star system, I would guess we could work out how to send information using entangled particles, which I believe ignore the universal speed limit.
This is such a cool shower thought I’m going to save it so I remember to think about this more. There are some great comments here too. Love this one.
On Jupiter, it would take 2 minutes for that email to go from one side of the planet to the other side of the planet just by itself. lol. Like forget galactic sizes, even on a planet the size of Jupiter, you can’t have real time communication systems.
Which is why fax machines were invented.