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As lim (pg. -> 100) 1/(100 - pg.) we are compelled to make a new [Science] thread.

SoggybiscuitSoggybiscuit 4.5 MV of POWER!Registered User regular
All sciences and related fields are welcome for discussion.

To start things off,

WARP DRIVE!

Well, not FTL, but a good theoretical foundation for warp drive (paper isn't available or on arXiv yet):



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Posts

  • Captain InertiaCaptain Inertia Registered User regular
    Ok I finally put my balls away

  • AbsoluteZeroAbsoluteZero The new film by Quentin Koopantino Registered User regular
    So we still don't have a way to make warp drive work without negative energy / mass, but according to this non-peer reviewed paper, warp drive slower than the speed of light is possible without negative energy / mass, but the video didn't really explain how that is supposed to work.

    I'm not going to get my hopes up until this goes through peer review and someone can explain it better.

    cs6f034fsffl.jpg
    Phoenix-DQuid
  • Jealous DevaJealous Deva Registered User regular
    Wouldn't a sub-light warp drive just be a ridiculously energy-intensive way of doing something that could be done conventionally anyway?

    zagdrob
  • MonwynMonwyn Registered User regular
    Wouldn't a sub-light warp drive just be a ridiculously energy-intensive way of doing something that could be done conventionally anyway?

    Doing it conventionally is, uh, also ridiculously energy-intensive.

    If you can go from zero to "almost, but not quite, c" at the flick of a switch it may be worthwhile since you'd be vastly decreasing your travel time.

    uH3IcEi.png
  • MorninglordMorninglord Registered User regular
    Could this negate relativistic time dilation?

    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • HappylilElfHappylilElf Registered User regular
    Could this negate relativistic time dilation?

    In theory

  • Jealous DevaJealous Deva Registered User regular
    edited November 2020
    Could this negate relativistic time dilation?

    I don’t think so. IIRC the time dilation cause by the compression and expansion of space ends up cancelling out to what the dilation would be if it had travelled the same distance in the same time conventionally when viewed by the rest of the universe. Same reason FTL warp drive still lets you time travel.

    Edit: apparently I’m misremembering on that, it looks from reading a bit that an FTL alciaberre drive would act like a “slow wormhole” and you could basically come out of the journey at whatever time you wanted relative to the rest of the universe? No clue how that would work slower than light.

    Jealous Deva on
  • MorninglordMorninglord Registered User regular
    edited November 2020
    Well, if it did negate it, this would be a very good reason to use it.

    Also it seems like the people/objects inside the bubble wouldn't have any g forces acting on them.

    So it'd be hella more manoeuvrable

    I think this would be quite a big deal if we could get it working.

    Morninglord on
    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • Jealous DevaJealous Deva Registered User regular
    edited November 2020
    Lots of weird shit happens when you get rid of time dilation though.

    There’s no real such thing as a universal time or t=0 across space.

    If you can make trips between places without time dilation (whether via wormhole or alcubierre drive or whatever) this essentially locks those places in a frame of reference with each other which doesn’t make sense when viewed against the rest of the universe.

    Like you travel to alpha centauri at .5c. You make a journey that from the point of view of Bob on earth looks like it takes about 17 years, but for you it only takes 15 years. Now your buddy Cal takes his alcubierre drive to Alpha Centauri that doesn’t experience time dilation but moves at an apparent speed of .5c from earths point of view. From Bobs point of view it takes 17 years, from Cals point of view it takes 17 years. However from your point of view it still takes 17 years for Cal to make his journey but only 15 for you (remember he hasn’t actually moved so his apparent time to you should look no different than someone still on earth). So Cal experiences no time dilation from Bobs point of view but experiences 2 years from your point of view. But why is Bob’s frame of reference privileged over yours in this case? From the point of view of earth you would both appear to be at the same point on every part of the journey and arrive at the same time, but from your view Cal would be behind you the whole way and would arrive at alpha centauri 2 years after you got there.

    Jealous Deva on
  • MorninglordMorninglord Registered User regular
    edited November 2020
    The universe is already weird. I'm sure we could work it out.

    I think the lack of g forces would basically enforce this drive becoming widely used if we move out into space in any real capacity, and especially if there's any kind of conflict. If it's possible to create it, of course.

    Morninglord on
    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • ScooterScooter Registered User regular
    Isn't time dilation on long interstellar journeys a good thing? Like, if you could travel at the speed of light, a trip to a star 10 LY away would feel instant to you, thanks to time dilation. But the same trip without time dilation would make it feel like 10 years. The only reason I can see to want that is if you need more reaction time to avoid stuff in your path or something.

  • Phoenix-DPhoenix-D Registered User regular
    Scooter wrote: »
    Isn't time dilation on long interstellar journeys a good thing? Like, if you could travel at the speed of light, a trip to a star 10 LY away would feel instant to you, thanks to time dilation. But the same trip without time dilation would make it feel like 10 years. The only reason I can see to want that is if you need more reaction time to avoid stuff in your path or something.

    Your reaction time doesn't really change. Time still runs at 1/s per 1/s.

  • ScooterScooter Registered User regular
    Phoenix-D wrote: »
    Scooter wrote: »
    Isn't time dilation on long interstellar journeys a good thing? Like, if you could travel at the speed of light, a trip to a star 10 LY away would feel instant to you, thanks to time dilation. But the same trip without time dilation would make it feel like 10 years. The only reason I can see to want that is if you need more reaction time to avoid stuff in your path or something.

    Your reaction time doesn't really change. Time still runs at 1/s per 1/s.

    Isn't that what it means to get rid of time dilation? At light speed, your reaction time is literally zero with time dilation. If it feels like 10 years instead, how would that not allow you to do things during those 10 years?

  • MorninglordMorninglord Registered User regular
    I'm more thinking about trips around our local system, where suddenly jumping up to significant percentages of C on a business trip to get to titan faster or something suddenly has a set of unfortunate problems once you get home.

    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • Phoenix-DPhoenix-D Registered User regular
    Scooter wrote: »
    Phoenix-D wrote: »
    Scooter wrote: »
    Isn't time dilation on long interstellar journeys a good thing? Like, if you could travel at the speed of light, a trip to a star 10 LY away would feel instant to you, thanks to time dilation. But the same trip without time dilation would make it feel like 10 years. The only reason I can see to want that is if you need more reaction time to avoid stuff in your path or something.

    Your reaction time doesn't really change. Time still runs at 1/s per 1/s.

    Isn't that what it means to get rid of time dilation? At light speed, your reaction time is literally zero with time dilation. If it feels like 10 years instead, how would that not allow you to do things during those 10 years?

    You can't actually ever hit c, for one. But no your personal time is always one second per second. It's everyone else that sees you running slow relative to them. Even if you somehow eliminated that effect- which is going to mean re-writing how we understand the universe- there's still the slight problem of the light delay. Anything you're seeing with will be moving almost your speed. It'd be like navigating a near-supersonic jet by sonar.

  • MorninglordMorninglord Registered User regular
    edited November 2020
    Why would it rewrite how we understand the universe? Time dilation only occurs if an object moves at speed within space time relative to an observer.

    If space time itself is moving, the current rules don't necessarily apply anymore.

    Morninglord on
    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • HydropoloHydropolo Registered User regular
    I'm not sure if you all, or I misunderstood the video. Basically, what this drive potentially allows you to do is adjust your relative time reference so that while you are travelling at .99bar c. you are still experiencing time relative to wherever (let's say earth). Essentially, you wouldn't experience time dilation, for good or bad.

  • chrisnlchrisnl Registered User regular
    Something I'm really curious about is if you can observe outside of the warp bubble from the inside, in this theoretical construction. There are a lot of very interesting possible interactions and I have no clue how it would play out. Like what does warping the fabric of space-time even look like to an outside observer? Even neglecting the possibility of going superluminal, there are a lot of very strange possibilities in play.

    steam_sig.png
  • MorninglordMorninglord Registered User regular
    Last time I looked into warp bubbles there was the problem of, when you stop, basically creating a massive flood of high energy exotic particles that would probably obliterate whatever was in front of you.

    So parking would be a somewhat delicate process.

    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
    GiantGeek2020ElvenshaeAbsoluteZeroTofystedethBrodykime
  • Inquisitor77Inquisitor77 2 x Penny Arcade Fight Club Champion A fixed point in space and timeRegistered User regular
    All sciences and related fields are welcome for discussion.

    To start things off,

    WARP DRIVE!

    Well, not FTL, but a good theoretical foundation for warp drive (paper isn't available or on arXiv yet):

    [snip]

    Thanks for the link. I ran across this other video in her channel that is both interesting and, at the very end, incredibly savage:

    Chanus
  • Jealous DevaJealous Deva Registered User regular
    The universe is already weird. I'm sure we could work it out.

    I think the lack of g forces would basically enforce this drive becoming widely used if we move out into space in any real capacity, and especially if there's any kind of conflict. If it's possible to create it, of course.

    Its not really a thing to work out, its honestly probably impossible just because of the way it fucks with the timeline, even if it doesn’t directly violate causality.

    Like in the example above, from the perspective of the two travellers, one has time to go get an associates degree on alpha centauri while the other doesn’t see any time at all between their arrival, the alcubierre guy literally sees them pull up at the same time while the normal travel guy sees himself as having 2 years of time to fuck around before the other guy gets there. An observer on alpha centauri would see a delay, but not one that exactly matches the first traveller IIRC. So you would have three people experiencing three different timelines and sequences of events, all of which could have different consequences on the future.

  • ChanusChanus I've seen things... Registered User regular
    All sciences and related fields are welcome for discussion.

    To start things off,

    WARP DRIVE!

    Well, not FTL, but a good theoretical foundation for warp drive (paper isn't available or on arXiv yet):

    [snip]

    Thanks for the link. I ran across this other video in her channel that is both interesting and, at the very end, incredibly savage:

    Sabine Hossenfelder is the hero we need

    Allegedly a voice of reason.
  • QuidQuid I don't... what... hnnng Registered User regular
    I have a Bachelor of Science in the Liberal Arts please feel free to ask me any science questions I am a scientist.

    ChanusGiantGeek2020ElvenshaeCaptain InertiaAbsoluteZeroTofystedethkimeJebus314DisruptedCapitalist
  • HonkHonk Honk is this poster. Registered User, __BANNED USERS regular
    Quid wrote: »
    I have a Bachelor of Science in the Liberal Arts please feel free to ask me any science questions I am a scientist.

    Is the earth a dragon?

    PSN: Honkalot
  • QuidQuid I don't... what... hnnng Registered User regular
    Honk wrote: »
    Quid wrote: »
    I have a Bachelor of Science in the Liberal Arts please feel free to ask me any science questions I am a scientist.

    Is the earth a dragon?

    No, this is a common misconception because people can see scaled legs over the edge, but the earth is actually a flat disc atop four elephants standing on a giant turtle swimming through space.

    ChanusHonkGiantGeek2020ElvenshaeCaptain InertiaAbsoluteZeroTofystedethboogedybooCarpyBrodyKruitekimeMcFodderDisruptedCapitalistHefflingPolaritiefurlion
  • ChanusChanus I've seen things... Registered User regular
    Lots of weird shit happens when you get rid of time dilation though.

    There’s no real such thing as a universal time or t=0 across space.

    If you can make trips between places without time dilation (whether via wormhole or alcubierre drive or whatever) this essentially locks those places in a frame of reference with each other which doesn’t make sense when viewed against the rest of the universe.

    Like you travel to alpha centauri at .5c. You make a journey that from the point of view of Bob on earth looks like it takes about 17 years, but for you it only takes 15 years. Now your buddy Cal takes his alcubierre drive to Alpha Centauri that doesn’t experience time dilation but moves at an apparent speed of .5c from earths point of view. From Bobs point of view it takes 17 years, from Cals point of view it takes 17 years. However from your point of view it still takes 17 years for Cal to make his journey but only 15 for you (remember he hasn’t actually moved so his apparent time to you should look no different than someone still on earth). So Cal experiences no time dilation from Bobs point of view but experiences 2 years from your point of view. But why is Bob’s frame of reference privileged over yours in this case? From the point of view of earth you would both appear to be at the same point on every part of the journey and arrive at the same time, but from your view Cal would be behind you the whole way and would arrive at alpha centauri 2 years after you got there.

    this isn't how relativity works

    no one standing on earth is going to see you traveling away from them at 0.5c and agree with you exactly on how long your trip took

    Allegedly a voice of reason.
  • Jealous DevaJealous Deva Registered User regular
    Chanus wrote: »
    Lots of weird shit happens when you get rid of time dilation though.

    There’s no real such thing as a universal time or t=0 across space.

    If you can make trips between places without time dilation (whether via wormhole or alcubierre drive or whatever) this essentially locks those places in a frame of reference with each other which doesn’t make sense when viewed against the rest of the universe.

    Like you travel to alpha centauri at .5c. You make a journey that from the point of view of Bob on earth looks like it takes about 17 years, but for you it only takes 15 years. Now your buddy Cal takes his alcubierre drive to Alpha Centauri that doesn’t experience time dilation but moves at an apparent speed of .5c from earths point of view. From Bobs point of view it takes 17 years, from Cals point of view it takes 17 years. However from your point of view it still takes 17 years for Cal to make his journey but only 15 for you (remember he hasn’t actually moved so his apparent time to you should look no different than someone still on earth). So Cal experiences no time dilation from Bobs point of view but experiences 2 years from your point of view. But why is Bob’s frame of reference privileged over yours in this case? From the point of view of earth you would both appear to be at the same point on every part of the journey and arrive at the same time, but from your view Cal would be behind you the whole way and would arrive at alpha centauri 2 years after you got there.

    this isn't how relativity works

    no one standing on earth is going to see you traveling away from them at 0.5c and agree with you exactly on how long your trip took


    Thats the point, if you strip time dilation out with some theoretical “warp drive” you get frame dragging, so someone travelling in an alcubierre drive would appear to be moving away at .5c to an ouside observer while still having their clocks agree with the person observing it. Which when viewed in the context of special relativity leads to all kinds of time travel, multiple timelines, etc.


    “Relativity does not work that way so its probably not possible” is literally the point.

  • ChanusChanus I've seen things... Registered User regular
    Chanus wrote: »
    Lots of weird shit happens when you get rid of time dilation though.

    There’s no real such thing as a universal time or t=0 across space.

    If you can make trips between places without time dilation (whether via wormhole or alcubierre drive or whatever) this essentially locks those places in a frame of reference with each other which doesn’t make sense when viewed against the rest of the universe.

    Like you travel to alpha centauri at .5c. You make a journey that from the point of view of Bob on earth looks like it takes about 17 years, but for you it only takes 15 years. Now your buddy Cal takes his alcubierre drive to Alpha Centauri that doesn’t experience time dilation but moves at an apparent speed of .5c from earths point of view. From Bobs point of view it takes 17 years, from Cals point of view it takes 17 years. However from your point of view it still takes 17 years for Cal to make his journey but only 15 for you (remember he hasn’t actually moved so his apparent time to you should look no different than someone still on earth). So Cal experiences no time dilation from Bobs point of view but experiences 2 years from your point of view. But why is Bob’s frame of reference privileged over yours in this case? From the point of view of earth you would both appear to be at the same point on every part of the journey and arrive at the same time, but from your view Cal would be behind you the whole way and would arrive at alpha centauri 2 years after you got there.

    this isn't how relativity works

    no one standing on earth is going to see you traveling away from them at 0.5c and agree with you exactly on how long your trip took


    Thats the point, if you strip time dilation out with some theoretical “warp drive” you get frame dragging, so someone travelling in an alcubierre drive would appear to be moving away at .5c to an ouside observer while still having their clocks agree with the person observing it. Which when viewed in the context of special relativity leads to all kinds of time travel, multiple timelines, etc.


    “Relativity does not work that way so its probably not possible” is literally the point.

    i think there's a misunderstanding of the time dilation issue

    the "no time dilation" only occurs inside the bubble, like locking yourself in a room

    it's still relativity to any observers, it's not like you can log in to harvard.edu and work on your associates degree while you're in the bubble. you're not actually breaking causality or anything like that. the whole idea of a tunnel in a wormhole is it exists outside of spacetime, allowing faster than light travel without requiring faster than light motion

    this bubble drive idea is basically that on a smaller scale that doesn't require negative energy

    Allegedly a voice of reason.
  • MorninglordMorninglord Registered User regular
    edited November 2020
    Travelling in a warp bubble completely sidesteps relativity.

    Relativity saying this cannot happen has no relevance to a warp bubble. It tells relativity to go get fucked.

    Or at least, that's my interpretation of how they work. Which you seem to agree with. You just seem to be saying "but this causes paradoxes, so that can't be possible"

    If it causes weird time travel shit, it causes weird time travel shit. If its possible, future people will just have to get very good at dealing with weird time travel shit.

    And if it is possible, they will.

    Morninglord on
    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • ChanusChanus I've seen things... Registered User regular
    weird time travel shit isn't a paradox if it doesn't affect causality

    you can take some textbooks with you in your bubble and complete an associates degree during your travel that you wouldn't have had time to do outside the bubble but that time still occurred to you

    Allegedly a voice of reason.
  • MorninglordMorninglord Registered User regular
    Chanus wrote: »
    Chanus wrote: »
    Lots of weird shit happens when you get rid of time dilation though.

    There’s no real such thing as a universal time or t=0 across space.

    If you can make trips between places without time dilation (whether via wormhole or alcubierre drive or whatever) this essentially locks those places in a frame of reference with each other which doesn’t make sense when viewed against the rest of the universe.

    Like you travel to alpha centauri at .5c. You make a journey that from the point of view of Bob on earth looks like it takes about 17 years, but for you it only takes 15 years. Now your buddy Cal takes his alcubierre drive to Alpha Centauri that doesn’t experience time dilation but moves at an apparent speed of .5c from earths point of view. From Bobs point of view it takes 17 years, from Cals point of view it takes 17 years. However from your point of view it still takes 17 years for Cal to make his journey but only 15 for you (remember he hasn’t actually moved so his apparent time to you should look no different than someone still on earth). So Cal experiences no time dilation from Bobs point of view but experiences 2 years from your point of view. But why is Bob’s frame of reference privileged over yours in this case? From the point of view of earth you would both appear to be at the same point on every part of the journey and arrive at the same time, but from your view Cal would be behind you the whole way and would arrive at alpha centauri 2 years after you got there.

    this isn't how relativity works

    no one standing on earth is going to see you traveling away from them at 0.5c and agree with you exactly on how long your trip took


    Thats the point, if you strip time dilation out with some theoretical “warp drive” you get frame dragging, so someone travelling in an alcubierre drive would appear to be moving away at .5c to an ouside observer while still having their clocks agree with the person observing it. Which when viewed in the context of special relativity leads to all kinds of time travel, multiple timelines, etc.


    “Relativity does not work that way so its probably not possible” is literally the point.

    i think there's a misunderstanding of the time dilation issue

    the "no time dilation" only occurs inside the bubble, like locking yourself in a room

    it's still relativity to any observers, it's not like you can log in to harvard.edu and work on your associates degree while you're in the bubble. you're not actually breaking causality or anything like that. the whole idea of a tunnel in a wormhole is it exists outside of spacetime, allowing faster than light travel without requiring faster than light motion

    this bubble drive idea is basically that on a smaller scale that doesn't require negative energy

    So you are saying that from the point of view of an observer outside the bubble there will still be relativistic time dilation? How can that be? Relativistic time dilation is what happens to objects that are moving through space time. This is not really moving through space time. It's space time itself moving. Where's the time dilation coming from?

    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • Jealous DevaJealous Deva Registered User regular
    edited November 2020
    Travelling in a warp bubble completely sidesteps relativity.

    Relativity saying this cannot happen has no relevant to a warp bubble. It tells relativity to go get fucked.

    Which is exactly why it fucks up the timeline, because the rest of the universe is still running on relativity.

    You can have a newtonian universe where time moves the same for everyone (well, we can’t, but such a universe could exist and be consistent.)

    You can have a relativistic universe where time varies by the frame of reference to the observer, and everything is logically consistent thorough being constrained by the speed of light.

    Having little bubbles of newtonian space-time within a relativistic universe fucks things up though. It really fucks things up if you can go faster than light because then you can do things like accidently or deliberately time travelIng by changing direction and violate causality by making closed time loops and the like. It fucks things up less with sublight speeds, but you still end up with things like different observers that end up in the same place but see events in a different order, or have large stretches of time that pop up or dissapear for the observer in the “bubble” vs the rest of the universe (not that they subjectively observe time differently, but that they literally arrive at a different time than they should from the view of the rest of the universe).

    Going slower than light actually fucks it up even more because at slower than light speeds the guy within the bubble can theoretically observe the rest of the universe and communicate with it while he or she is traveling.

    Jealous Deva on
  • MorninglordMorninglord Registered User regular
    edited November 2020
    Travelling in a warp bubble completely sidesteps relativity.

    Relativity saying this cannot happen has no relevant to a warp bubble. It tells relativity to go get fucked.

    Which is exactly why it fucks up the timeline, because the rest of the universe is still running on relativity.

    You can have a newtonian universe where time moves the same for everyone (well, we can’t, but such a universe could exist and be consistent.)

    You can have a relativistic universe where time varies by the frame of reference to the observer, and everything is logically consistent thorough being constrained by the speed of light.

    Having little bubbles of newtonian space-time within a relativistic universe fucks things up though. It really fucks things up if you can go faster than light because then you can do things like accidently or deliberately time travelIng by changing direction and violate causality by making closed time loops and the like. It fucks things up less with sublight speeds, but you still end up with things like different observers that end up in the same place but see events in a different order, or have large stretches of time that pop up or dissapear for the observer in the “bubble” vs the rest of the universe (not that they subjectively observe time differently, but that they literally arrive at a different time than they should from the view of the rest of the universe).

    Yes.
    And?

    Last I checked physicists would be pretty okay with time being fucked up because they don't even really believe time is a straight line from start to end anyway.

    I'm saying if its fucked up, we'd figured out what to do with it. It'd be very interesting times, and nothing like we previously have known. But we'd adapt.

    "Time gets fucked up" is not a sufficient reason to say "and so this can't happen".

    Morninglord on
    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
    ChanusMeeqe
  • ChanusChanus I've seen things... Registered User regular
    i'm not saying it's not weird, i'm just saying it doesn't break causality or do anything impossible (at least, as far as the math shows)

    Allegedly a voice of reason.
    Morninglord
  • MorninglordMorninglord Registered User regular
    edited November 2020
    Also I wanted to post these two videos because I found them super interesting in how they completely upended some closely held assumptions I've been making about the two topics in these videos. The speed of light and how gravity works.





    edit:

    And this one, which is about how space expanding doesn't mean local spacetime we experience is expanding.

    Morninglord on
    (PSN: Morninglord) (Steam: Morninglord) (WiiU: Morninglord22) I like to record and toss up a lot of random gaming videos here.
  • WinkyWinky rRegistered User regular
    Also, I'm pretty sure you and Cal would arrive at the same time, you would just disagree about how long it took.

    ChanusBrody
  • Jealous DevaJealous Deva Registered User regular
    edited November 2020
    Chanus wrote: »
    weird time travel shit isn't a paradox if it doesn't affect causality

    you can take some textbooks with you in your bubble and complete an associates degree during your travel that you wouldn't have had time to do outside the bubble but that time still occurred to you

    Thats not what happens.

    What happens is that to the guy in the bubble he literally arrives at the same time as the guy who travelled conventionally. He pulls up on the landing pad at the same time, shakes his hand, both arrive simultaneously.

    For the guy who went in the regular spaceship he gets to alpha centauri, takes a community college class, gets married, has a kid, takes a taxi 2 years later and meets warp bubble guy at the launch pad, and shakes his hand.

    At no point is there a mechanism to reconcile these alternate chains of events, both guys proceed to live the rest of their lives as if their version of things happened but somehow still occupy the same universe and can exchange information with each other the whole time.

    Jealous Deva on
  • WinkyWinky rRegistered User regular
    Also, it looks like the debate regarding the presence of phosphine on Venus is ongoing. Things don't look particularly great for the first detection, as some refutations have been published already and one of the two telescopes they used was shown to have calibration issues at the time it was detected, though apparently re-analyzed results after recalibration still show a signal but at a lower ppm than originally detected. The fact that they weren't able to reproduce the results on a different part of the spectrum (yet, at least) is probably the most damaging evidence against it so far, though. That said, things seem far from settled yet.


  • WinkyWinky rRegistered User regular
    edited November 2020
    Chanus wrote: »
    weird time travel shit isn't a paradox if it doesn't affect causality

    you can take some textbooks with you in your bubble and complete an associates degree during your travel that you wouldn't have had time to do outside the bubble but that time still occurred to you

    Thats not what happens.

    What happens is that to the guy in the bubble he literally arrives at the same time as the guy who travelled conventionally. He pulls up on the landing pad at the same time, shakes his hand, both arrive simultaneously.

    For the guy who went in the regular spaceship he gets to alpha centauri, takes a community college class, gets married, has a kid, takes a taxi 2 years later and meets warp bubble guy at the launch pad, and shakes his hand.

    At no point is there a mechanism to reconcile these alternate chains of events, both guys proceed to live the rest of their lives as if their version of things happened but somehow still occupy the same universe.

    I don't think this is how it works. If Bob were standing on Alpha Centauri he would still perceive the trip as having took you 17 years, not 15 (after he accounts for the time it took light from Earth showing you taking off to reach him). You're the only one who experiences it as 15 years.

    (Okay this is maybe fudged a little bit because it assumes Alpha Centauri and Earth are stationary relative to each other, which they are not, but they are certainly far closer to stationary relative to each other than they are relative to you and Cal.)

    Winky on
    Chanus
  • Jealous DevaJealous Deva Registered User regular
    Winky wrote: »
    Chanus wrote: »
    weird time travel shit isn't a paradox if it doesn't affect causality

    you can take some textbooks with you in your bubble and complete an associates degree during your travel that you wouldn't have had time to do outside the bubble but that time still occurred to you

    Thats not what happens.

    What happens is that to the guy in the bubble he literally arrives at the same time as the guy who travelled conventionally. He pulls up on the landing pad at the same time, shakes his hand, both arrive simultaneously.

    For the guy who went in the regular spaceship he gets to alpha centauri, takes a community college class, gets married, has a kid, takes a taxi 2 years later and meets warp bubble guy at the launch pad, and shakes his hand.

    At no point is there a mechanism to reconcile these alternate chains of events, both guys proceed to live the rest of their lives as if their version of things happened but somehow still occupy the same universe.

    I don't think this is how it works. If Bob were standing on Alpha Centauri he would still perceive the trip as having took you 17 years, not 15 (after he accounts for the time it took light from Earth showing you taking off to reach him). You're the only one who experiences it as 15 years.

    (Okay this is maybe fudged a little bit because it assumes Alpha Centauri and Earth are stationary relative to each other, which they are not, but they are certainly far closer to stationary relative to each other than they are relative to you and Cal.)

    Thats what normally happens in relativistic travel. Time travels slower for the traveller than either destination (note normally clocks aren’t going to be the same at all on alpha centauri or earth, they are also moving relative to each other). But because the speed of light is an inherent limiter of the speed of travel in relativity, paradoxes get rectified.

    Its totally possible from a pair of arbitrary points of view in special relativity for two observers to observe a set of events in different locations in a different order (ie from the milky way you may see a distant supernova in galaxy A occur before B, but from andromeda you may see galaxy b have a supernova before galaxy a). But because of the speed of light limiting flow of information and therefore causality itself every observer internal to the system has a consistent point of view in which causality is maintained.


    Because the alcubierre drive is letting you keep the frame of reference of Earth while physically being adjacent to alpha centauri, you are suddenly allowing paradoxes in perspective to have a meaningful impact on events, in a way that just traveling there conventionally doesn’t (because the speed of light and subjective time dilation prevents such paradoxes from occurring and actually mattering, everything “cancels out” so that a coherent time line is visible to any observer which agrees reasonably with any other observer as to “what is actually going on right now at this moment” provided they are in the same location).

    This is literally what special relativity does, and anything that bypasses it is going to need to have another mechanism to reconcile synchronicity at local distances and resolve paradoxes, or have observers at the same location disagreeing about what they are observing in the “present”.

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