[HN Gopher] New study simulates gravitational waves from failing...
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New study simulates gravitational waves from failing warp drive
Author : nabla9
Score : 116 points
Date : 2024-07-29 15:23 UTC (1 days ago)
(HTM) web link (www.aei.mpg.de)
(TXT) w3m dump (www.aei.mpg.de)
| oulu2006 wrote:
| I love the summary:
|
| "we study the signatures arising from a warp drive 'containment
| failure', ...."
|
| "Our work highlights the importance of exploring strange new
| spacetimes, to (boldly) simulate what no one has seen before."
|
| Have just been re-watching StarTrek Voyager.
| vessenes wrote:
| I love, so much, the idea that we might get a sort of galactic-
| scale AAA roadside warning service "Uh-oh, 2 billion years ago
| somebody's warp drive went wonky in Sector ZZ9 Plural Z Beta"
| before we can easily move around our own Solar System. Humans
| would be like the old guy in a neighborhood listening to the
| police scanner, essentially.
| floren wrote:
| This was done computationally, no gravitational waves actually
| came into existence.
| jkingsman wrote:
| I think the commenter's point was that a model for detecting
| events caused by advanced tech before we even get our space
| exploration training wheels off would be a funny irony.
| Already__Taken wrote:
| kinda the premise of Stargate where most aliens copied
| other aliens advanced tech. So actually anyone who could
| build it from scratch was kinda rare.
| thaumasiotes wrote:
| > kinda the premise of Stargate where most aliens copied
| other aliens advanced tech
|
| This is how all technology has always worked.
| noduerme wrote:
| Pyramids, writing, and agriculture with irrigation
| developed independently in at least two completely
| separate places on Earth within just the last 3000 years.
| thaumasiotes wrote:
| And, as a percentage of cultures using pyramids, writing,
| and agriculture, that would be...?
| dumpsterdiver wrote:
| Irrelevant.
| thaumasiotes wrote:
| I think you mean "zero". Why would you expect technology
| to work any differently between planets?
| dumpsterdiver wrote:
| No, I mean irrelevant, as is your newest argument. The
| functional capabilities of technology between planets is
| irrelevant to the observation that disparate groups
| develop similar levels of technology independently.
| exe34 wrote:
| precisely
| noduerme wrote:
| This is survival bias. As of 1000 years ago, the answer
| was an entire hemisphere. So as long as barriers like
| oceans or space between stars slow the propagation of
| technology, technology will develop on its own.
| thaumasiotes wrote:
| > As of 1000 years ago, the answer was an entire
| hemisphere.
|
| You honestly believe that there was just one culture
| across the entire geographical and historical extent of
| the Americas, despite not believing the same thing about
| the Old World?
| pkaeding wrote:
| Developed independently? Or were both visited by aliens
| sharing the ideas?
| quotemstr wrote:
| The absence of such detections is yet another unsettling
| input to the Fermi paradox.
| marshray wrote:
| On the bright side, maybe it is evidence against Dark
| Forest theory?
| shepardrtc wrote:
| The Dark Forest theory is fear-mongering anyway. If
| there's a civilization out there that wants to conquer
| others, it just has to send a probe to every star out
| there. Sufficiently advanced automation would allow this
| to happen without much work on their part. In theory, WE
| could do that right now, though very clumsily and with
| many failures. 3D printing, AI, harvesting materials off
| asteroids. Not outside of possibility, just hard at our
| level of tech. Now imagine the boogeyman of the Dark
| Forest theory - they would obviously have a greater level
| of tech if they're so dangerous, and it would be much
| easier.
| SoftTalker wrote:
| Why unsettling?
| quotemstr wrote:
| https://en.wikipedia.org/wiki/Great_Filter
| kevin_thibedeau wrote:
| You don't need FTL travel to expand into our light cone
| at this point in the evolution of the universe.
| pfdietz wrote:
| That makes absence of FTL detections comforting, not
| unsettling.
| 7thaccount wrote:
| I saw something recently that one explanation is that we're
| in a cosmic void. Sure the milky way is big, but we're
| still exposed to a fraction of the worlds that a non-void
| area would be.
|
| Of course there are 80,000 other explanations that are also
| fascinating. A wonderful subject.
| IsTom wrote:
| For me what makes most sense is that we're relatively
| early in cosmic history. You need enough heavy (and
| diverse!) elements to be able to support
| life/civilization and you won't get that from early
| stars.
| jajko wrote:
| Most probably yes, I mean we only have few generation of
| stars actually producing heavy elements enough to see
| what we see ie on Earth, not just some hydrogen & helium
| ball.
|
| Also most probably there isnt any way to travel back in
| time, since we would most probably be eliminated at the
| seed to not compete for resources or avoid aggression.
| For all wonderful things mankind did and does, we are
| still deeply flawed and highly emotional primitive
| beings, and we may kill ourselves due to this.
| JoeAltmaier wrote:
| The real tragedy, we're taking so many others with us.
| BriggyDwiggs42 wrote:
| On cosmic scales of time, theres no reason to assume
| spacefaring humans would remotely resemble us in any
| recognizable way. Imo especially their minds, they'd
| almost certainly have augmented and modified their
| thinking drastically.
| wongarsu wrote:
| And earth has been around for 1/3rd of the current age of
| the universe. As far as things go it's pretty old.
|
| Add to that that we probably aren't as "normal" as we
| initially believed. A solar system with small rocky
| planets on the inside and big gas giants on the outside
| seems to be the exception and was very important for
| earth's development. Then there's the above mentioned
| "void" we are in, and probably other things we don't
| realize yet.
|
| There's a really good case that we are among the earliest
| spacefaring civilizations
| shepardrtc wrote:
| Well don't forget that Earth had it's reset button
| smashed 66 million years ago. Let's say another world
| started out at the same as we did but never encountered
| such a cataclysm. Even if they took an additional 65
| million years to develop, they'd still be a million years
| older than us.
| quotemstr wrote:
| The KT boundary is hardly a "reset button smashed". Yes,
| it was a mass extinction event, but these things happen.
| The products of billions of years of evolution survived,
| even if megafauna had a setback. Evolution spent billions
| of years figuring out basic things like the genetic code,
| sexual reproduction, and mitochondria. All these
| technologies survived the KT boundary. Complex
| multicellular life emerged only about 560 million years
| ago (after single-celled life had been around for
| _billions_ of years). The implication is that the early
| innovations in life (ribosomes, etc.) were "harder" than
| later ones involving eyes, brains, and so on.
|
| A "reset button" would be more like the impact that
| created the moon: ramming a Mars-sized body into Earth
| turns Earth into a magma ocean. Nothing survives that. By
| comparison, the KT boundary asteroid is small potatoes.
| mr_mitm wrote:
| Or warp drives are simply impossible or at least ultra
| unfeasible. Nothing unsettling about that thought.
| quotemstr wrote:
| Superluminal travel being infeasible probably limits our
| species to our own solar system.
| evilduck wrote:
| You don't need anything near light speed for single human
| lifetimes to navigate beyond the solar system but it will
| be a one way trip mostly devoid of communication. We can
| seed the galaxy but can't watch it bloom.
| JumpCrisscross wrote:
| > _but it will be a one way trip mostly devoid of
| communication_
|
| Which describes our species' travels until only a few
| thousand years ago.
| Loughla wrote:
| It is unsettling though. Because it places a limit on
| what has so far been essentially limitless success as a
| species.
|
| Without travel beyond our solar system, we won't last
| forever.
|
| And that's kind of sad for me.
| dTal wrote:
| We won't last forever anyway. Nothing does.
| rkagerer wrote:
| If I was a really advanced civilization and the universe
| was nearing its end, I'd embark on a project of
| unparalleled scale that might wind up resembling a big
| bang with a spark of panspermia-precursor seasoned in.
| luxpir wrote:
| Goosebumps thinking of how many universes could have
| played out before this one. Or alongside it.
| lloeki wrote:
| Goosebumps just with ours already:
| https://m.youtube.com/watch?v=uD4izuDMUQA
| mab122 wrote:
| May I... https://en.wikipedia.org/wiki/The_Last_Question
| worstspotgain wrote:
| Indeed, we know so little about the nature of things that
| it's really a bit premature to hold our current
| understanding as the final word over what will happen.
|
| For one thing, a large fraction of possibilities involves
| simulations. In a simulation with successful traits, some
| constants and elementary particles might turn out to have
| been misunderstood later on...
| tshaddox wrote:
| Doesn't seem like a limit to me, other than a limit on
| speed (and of course there will be limits on speed).
| ben_w wrote:
| We don't need a warp drive to get to the next star, it
| would just make it faster.
| wongarsu wrote:
| Exactly. If we set our minds to it and dedicated enough
| resources we could likely reach the next star within the
| century: 40 years travel time at 0.1c with something like
| nuclear pulse propulsion, and we could probably get the
| remaining technical challenges for achieving that out of
| the way in 30 years.
| SanderNL wrote:
| It's sad to not last forever? That's an interesting
| thought. I understand, don't get me wrong, but it's
| completely unnatural in so many ways.
| baq wrote:
| In a physically constrained system all exponential growth
| becomes at best a sigmoid sooner or later... it's only
| sad if you let it make you feel this way.
| pfdietz wrote:
| We don't need FTL to colonize beyond the solar system,
| not at all.
| rkagerer wrote:
| Not unsettling, but a little bit melancholy.
| downrightmike wrote:
| If you're spending at least a quadrillion dollars to build
| a warp drive, you better make sure it doesn't fail or fails
| safe. We may never see a failure, even if we make it
| depending on where it is.
| exe34 wrote:
| if they have accountants, CEOs and shareholders, they'll
| cut corners.
| K0balt wrote:
| No worries, it will be built by Boeing.
| pfdietz wrote:
| Unsettling? It's highly comforting.
|
| What would be horribly unsettling is detection of ET
| intelligence, as it would imply either interstellar travel
| is impossibly difficult or that the Great Filter is in our
| future.
| hoseja wrote:
| Or the ETs know about signal hygiene. Hell, careless warp
| drive signatures are even a plot point in Three Body
| Problem.
| thegrim33 wrote:
| We have no gravitational wave detectors with the
| sensitivity at the needed frequencies to be able to detect
| such events.
| mystified5016 wrote:
| We haven't actually looked for them yet. The frequency of
| the theoretical gravitational waves is also beyond what our
| current detectors can reasonably pick up.
|
| IIRC, a warp bubble a few km in diameter moving at <0.3c
| produces gravitational waves at a frequency just beyond
| what we can currently detect. Superluminal warp bubbles
| haven't been simulated, apparently that's beyond the
| computational resources available to this team.
|
| Don't expect a real detection any time soon. We'll need
| another generation or two of development on our detectors
| and to actually simulate a more realistic (small and
| superluminal) warp field.
|
| Personally, I think we'll find _something_ once we build
| detectors good enough. I 'm a firm believer that purely
| based on statistics there has to be someone else out there.
| I also choose to believe that superluminal travel is
| possible because the universe would be a much less
| interesting place otherwise.
| m463 wrote:
| the trick is to say:
|
| Looks like your ship has a mechanical problem <click for
| more...>
|
| and collect click information about their civilization before
| they get any information about their warp drive
| dreamcompiler wrote:
| Or like the Vulcans, who were constantly listening for warp
| signatures and thus discovered the humanoids of Earth after
| Zefram Cochrane invented the warp drive.
|
| https://en.m.wikipedia.org/wiki/Zefram_Cochrane
| josefritzishere wrote:
| They're simulating imaginary things?
| throwaway48540 wrote:
| The latest research in this field says it's physically (not
| just mathematically) possible - negative energy is no longer a
| requirement.
| vlovich123 wrote:
| Do you have any pointers?
| throwaway48540 wrote:
| https://www.space.com/warp-drive-possibilities-positive-
| ener...
| LeifCarrotson wrote:
| https://arxiv.org/pdf/2405.02709
|
| https://github.com/NerdsWithAttitudes/WarpFactory
|
| I'm impressed that they've removed the requirement for
| negative energy, but it's not quite ready to hand the
| drawings to your local machine shop to build one. It
| requires matter packed to an energy density on the order
| of 10^39 joules per cubic meter.
|
| According to [1], oil has a (chemical) energy density of
| 4.5x10^10 joules per cubic meter, purified uranium
| produces 1.5x10^15 J/m^3 in a fission reactor, and that
| same uranium in pure mass-to-energy conversion produces
| on the order of 10^21 J/m^3. Uranium has a density of
| 19x10^3 kg/m^3, and the nucleus of an atom or neutron
| star has a density on the order of 4x10^17...if you can
| build the entire ship out of pure neutrons, you're still
| coming up short by a factor of ~100.
|
| All that does suggest that it seems reasonable we'd be
| able to observe gravity waves from a long distance if a
| machine like that ever experienced a loss of compression.
|
| [1]: https://drexel.edu/~/media/Files/greatworks/pdf_sum1
| 0/WK8_La...
| adamnew123456 wrote:
| > and the nucleus of an atom or neutron star has a
| density on the order of 4x10^17...if you can build the
| entire ship out of pure neutrons, you're still coming up
| short by a factor of ~100
|
| Would you be getting into black hole territiry at that
| density?
| acchow wrote:
| > not just mathematically
|
| Let's be clear here. Alcubierre's original "warp drive" idea
| was for super-luminal speeds (faster than light) and required
| "exotic matter" (negative energy).
|
| This new one is for sub-luminal speeds (slower than light).
| It does not require "exotic matter", but it's hardly a "warp
| drive"
| JumpCrisscross wrote:
| > _it 's hardly a "warp drive"_
|
| Why not? From my understanding, to the ship's occupants,
| they'd be travelling (EDIT: subjectively) super-luminally.
| In one lifetime they could go more than 100 ly.
| mr_mitm wrote:
| That doesn't match any definition of super-luminal that I
| have ever seen. Super-luminal means faster than light,
| period.
| JumpCrisscross wrote:
| > _doesn 't match any definition of super-luminal that I
| have ever seen_
|
| I didn't say it's physically super-luminal. The undefined
| term is "warp drive."
|
| Given the ship's occupants would subjectively travel
| super-luminally, it would seem to tick the boxes for
| warp. If it worked, you or I could travel to the other
| side of the galaxy. Hundreds of thousands of years would
| have elapsed outside the bubble. But we'd be alive.
| marshray wrote:
| Typically we think of "speed" as observed from outside
| the moving [object], but I guess "typically" it doesn't
| matter.
|
| I think it's an interesting point and you're not wrong to
| say it ticks at least one of boxes. It just doesn't match
| the concept that people have in mind, so an otherwise
| interesting discussion ends up rat-holing on semantics.
| JumpCrisscross wrote:
| > _Typically we think of "speed" as observed from outside
| the moving_
|
| Is it? We don't colloquially consider the Earth's
| rotation or revolution.
|
| This isn't a _Star Trek_ warp drive. But dismissing it as
| "hardly a warp drive" seems categorically wrong.
| mr_mitm wrote:
| Sub luminal speeds are in an entirely different category
| than super luminal speeds. It's hard to overstate how
| different it is, so the original objection is completely
| appropriate. You can argue about the wording, but what's
| the point in that? Everyone with half a brain agrees on
| the facts.
| marshray wrote:
| I don't recall having considered this point before,
| though granted I will call half a brain a good day.
| marshray wrote:
| > We don't colloquially consider the Earth's rotation or
| revolution.
|
| Wasn't this choice of reference frame the basis for that
| whole drama with Galileo, or am I misunderstanding?
| groby_b wrote:
| We discovered a couple of centuries later that there's
| more than one reference frame, you can choose, and the
| choice matters. It's been a pretty interesting
| development!
| zmgsabst wrote:
| I don't think it's a "warp drive".
|
| It's a "warp stasis" bubble or field: you've effectively
| suspended (or considerably slowed) the people inside to
| preserve them for the future -- stasis.
|
| I think you're running into objections because while it
| is warp technology, it's not a _drive_ in that it's not
| providing atypical propulsion (ie, Star Trek warp drives,
| Star Wars hyperspace drives, Babylon 5 subspace jump
| drives, etc).
|
| You're correct that we're trying to define "warp drive",
| but each of "warp" and "drive" are used independently --
| and your usage of "warp drive" doesn't respect their
| independent usage. That you have a 1:1000 slowdown in
| perceived time to real time as your example suggests at
| some level you recognize this isn't a _drive_.
|
| I think warp _stasis_ is a super cool technology all on
| its own, though.
| lloeki wrote:
| > it's not a drive in that it's not providing atypical
| propulsion (ie, Star Trek warp drives,
|
| AIUI in Star Trek, Cochrane's "space warp generator" and
| descendants are essentially the Alcubierre design: I
| don't seem to understand that the warp bubble provides
| any propulsion by itself (although grav waves could be
| surfed)
|
| Instead AIUI actual movement is created by a secondary
| mechanism, which I'm unclear about from a cursory search.
| Maybe impulse engines? Or maybe those are
| inefficient/incompatible with warp and it's using a
| secondary system that comes as a (intentional by design)
| byproduct of nacelles, like a ramjet engine airplane
| essentially has two propulsion systems since requires
| forward speed so you gotta have regular engines.
| altruios wrote:
| Being able to move space around a ship, and being able to
| move space around a ship faster than the speed of light
| seem to require orders of magnitude different energies.
| being in a 'warp bubble' doesn't mean that bubble is
| traveling at super luminal speeds.
| JumpCrisscross wrote:
| > _being able to move space around a ship faster than the
| speed of light seem to require orders of magnitude
| different energies_
|
| They require different _kinds_ of energies. Specifically,
| the latter requires negative energy, something we have no
| evidence exists.
|
| > _being in a 'warp bubble' doesn't mean that bubble is
| traveling at super luminal speeds_
|
| Nobody claimed as much. The physically-possible warp
| bubble lets you slow down time. So a 100,000-year journey
| would feel, to the ship's occupants (and its structure
| and computers, _et cetera_ ), like possibly months.
|
| (You also get the capability to transport people and
| things forward in time without degradation. Or, I
| believe, to speed up time inside _e.g._ a production or
| computational environment.)
| altruios wrote:
| > The physically-possible warp bubble lets you slow down
| time.
|
| that... seems odd to me. without substantial changes in
| velocity - how does a warp bubble (that's sub-luminal -
| so relativistic velocities) alter the fabric of space-
| time so fantastically? It's not moving fast: so where
| does the time dilation come from?!
| JumpCrisscross wrote:
| > _not moving fast: so where does the time dilation come
| from?!_
|
| I think it's from shifting momentum?? The paper is far
| beyond me [1]. But as I understood it, you're directly
| modifying space-time with energy instead of using
| acceleration as a go-between.
|
| [1] https://arxiv.org/html/2405.02709v1
| ben_w wrote:
| The mass distribution in the metric can do that; IIRC
| this was chosen in order to _not_ have time dilation, so
| I think someone 's getting confused (and maybe that
| someone is me?)
| wyago wrote:
| The main appeal of FTL is I think the ability to return
| to where you came from. If 1000 years pass before your
| return, it would only be superficially the same place.
| That being said I would think that the defining feature
| of a warp drive would be that it uses warped spacetime
| for motion rather than propellant.
| JumpCrisscross wrote:
| > _main appeal of FTL is I think the ability to return to
| where you came from_
|
| If that's your metric this isn't the warp drive for you.
| That hardly means it isn't a warp drive. The lifetime-
| lightyear travel boundary for possible experiences would
| be breached.
| andreasmetsala wrote:
| Can a normal drive even do that?
| hoseja wrote:
| You can travel arbitrary distances in one lifetime, even
| with just constant 1g acceleration. It's just that aeons
| will pass for the outside observers.
| knappe wrote:
| You could have said that about the Nice model until we found it
| explained a lot of the early solar system formation and unified
| a lot of disparate working theories.
|
| https://en.m.wikipedia.org/wiki/Nice_model
| rbanffy wrote:
| They are imaginary just until their first detection.
| JumpCrisscross wrote:
| > _simulating imaginary things?_
|
| Doesn't this describe the lead up to any theoretical
| breakthrough?
| itishappy wrote:
| By definition. That's what simulation means. ;)
| JumpCrisscross wrote:
| > _That 's what simulation means_
|
| Not really. Utah teapots are simulations of known objects
| [1]. Flight simulators of known phenomenon.
|
| This is closer to Einstein or Schwarzschild's theorising.
|
| [1] https://en.m.wikipedia.org/wiki/Utah_teapot
| itishappy wrote:
| Utah teapot is not real (it cannot hurt you). Despite being
| based on actual physical things, no Utah teapot will ever
| hold tea.
|
| A simulation cannot be real. Results obtained from a real
| object are measurements.
| JumpCrisscross wrote:
| The simulation is an imaginary thing. It is simulating
| something that is not imaginary.
|
| If I'm simulating a bug, it doesn't make the bug
| imaginary. The simulation is immaterial. (I wouldn't
| quite call it imaginary. Computers don't imagine.) But I
| am simulating a real thing. If, on the other hand, I
| simulate a bug the size of Paris, I am simulating
| something imaginary.
|
| All simulations are immaterial. But the things they are
| _simulating_ can be real or imagined.
| itishappy wrote:
| I understand, completely agree, and plan to continue
| digging myself into this pedantic hole anyway thank you
| very much.
|
| Interesting that a difference of scale alone determined
| the nature of a thing! More interesting, perhaps, are the
| number of factors that aren't considered!
|
| Would a simulation of a Peruvian ant on the Tibetan
| Plateau be real or imagined? What about a simulation of
| an ant after 20 years of climate change? How about an ant
| in space or experiencing the Big Bang?
|
| On the other hand, is a simulation of a black hole real
| or imaginary? What about simulations of the history of
| the universe involving dark matter and dark energy?
|
| I appreciate a sibling comment's (thanks marshray)
| suggestion that there exists a spectrum of
| theoreticalness. Theoreticity?
|
| > the simulation in this paper is theoretical to a much
| larger degree than that of the teapot.
| Joker_vD wrote:
| > If, on the other hand, I simulate a bug the size of
| Paris, I am simulating something imaginary.
|
| Are you _really_ sure about that?
| alfiedotwtf wrote:
| The original Utah Teapot is definitely real and can hold
| tea :)
| itishappy wrote:
| I could certainly use some tea now to wash away the taste
| of the foot I just pulled from my mouth.
|
| However, as an enjoyer of pedantic semantics, is the real
| Utah Teapot the physical pot or the model?
| marshray wrote:
| I've personally seen the physical teapot in the Computer
| History Museum.
|
| We routinely make detailed simulations of how such a
| physical teapot interacts with visible wavelengths of
| light, specifically for the purpose of comparing them
| with reality. From this we know that we do in fact have
| the ability to simulate this aspect of reality to a high
| degree of precision.
|
| The ability to detect gravitational waves is just
| recently coming on-line, and we have no example of an
| actual warp drive to measure, so the simulation in this
| paper is theoretical to a much larger degree than that of
| the teapot.
| kelseyfrog wrote:
| What parent is trying to say is that they are about as
| similar as the map and the territory
|
| Or you may have heard as it as all models are wrong
| smeagull wrote:
| Things don't have to be real for them to hurt you.
| itishappy wrote:
| I'm hurt that you'd imply that.
|
| https://knowyourmeme.com/memes/skull-cow-isnt-real-it-
| cant-h...
| mr_mitm wrote:
| They do that all the time.
| colechristensen wrote:
| This is how a lot of science works. You guess that something
| exists and works a certain way, you build a model, then you see
| what measurable things that model predicts.
|
| Gravitational waves themselves were "imaginary" for a century
| or more (depending on who you credit) until they were directly
| measured in 2015.
| exe34 wrote:
| isn't that like 99% of modern mathematics?
| Tomte wrote:
| PBS Spacetime: https://youtu.be/8hvzF5oQe1g?si=dU7YRdomARPQzDtd
| rbanffy wrote:
| A positive would mean two amazing news at once: that there are
| aliens travelling in deep space and that they do so using faster-
| than-light spaceships.
| Filligree wrote:
| Only one of those. Warp fields are useful if they can be made,
| but probably won't allow for FTL.
| quotemstr wrote:
| Right. Because FTL, no matter its form, breaks causality.
| JonChesterfield wrote:
| And causality is known to be axiomatic because?
| Joker_vD wrote:
| Because it seems to hold empirically quite stubbornly.
| K0balt wrote:
| Not really at the quantum level, at least not in the form
| that is typically understood as causality. There are all
| kinds of ways that you can interfere with probability and
| when you do, the "no taksie-backsies" rule goes out the
| window. You can prove this to yourself with a flashlight
| and 3 diffraction gratings.
| Filligree wrote:
| Only if you don't think MWI is accurate...
| K0balt wrote:
| That's where probability manipulation really gets
| interesting.
|
| My preferred conjecture is that all things exist, at all
| times, in all places, but only a fraction of all of those
| infinite-dimensional probability vectors will produce the
| act of your observation, so those are all of the vector-
| spaces that you can detect. We can't observe, for
| example, a probability vector-space where water boils at
| 15c/1bar, or where e=3 because we would never have
| existed to observe within that environment. Perhaps other
| things exist and observe those places, but not carbon
| based biological life as we know it.
|
| I think that the Casimir effect and especially Casimir
| pressure in constrained geometries, Zero point energy,
| the uncertainty principle and other observable phenomena
| point towards the possibility of a continuum of multiple
| overlapping observable probability fields, but obviously
| that could be just a convenient hand wavy explanation.
|
| In the bandwidth of overlapping probability fields
| flavour of MWI there is no branching or creation of new
| realities, merely extant vector spaces drifting in and
| out of observability based on probabilistic functions.
| Vector spaces within observability tend to be similar,
| and the overall aggregate sum is what we perceive as a
| unified observation.
|
| As we make changes that manipulate this probability
| space, new probabilities dominate our perception. The
| apple was very unlikely to be seen on the table until we
| moved it there, making it then extremely probable to be
| observed in that position.
|
| There are some very interesting ramifications that appear
| to be observable phenomena if this line of thought is
| drawn out to its extrema. It's one of my favourite
| possible models.
|
| Perhaps one day I or someone else will figure out how to
| experimentally test the idea, but so far it seems to be
| unfalsifiable (which obviously doesn't mean that it is
| more correct, just that it's hard to test, like the
| simulation conjecture and many others)
| Joker_vD wrote:
| Um, sorry, how does that experiment prove anything
| quantum? It's explained entirely by Malus' law of I = I0
| * cos^2(alpha) which has an entirely classical, simple
| wave-theoretical explanation (even if Malus himself was
| an emissionist and derived his law by introducing
| transversal asymmetry in the light corpuscles).
| K0balt wrote:
| Malus's law does indeed describe the amplitudes of the
| resulting light, but it does not say "why", only how. In
| the same way that Newtonian physics assumes gravity but
| fails to explain its existence.
|
| For more in depth look at this there is a 1995 paper by K
| Wodkiewicz contrasting the corpuscular formula with the
| quantum explanation IIRC.
|
| Obviously, despite its explanatory power, we know that QM
| is incomplete so YMMV, but I'll take QM over light
| corpuscles, until something better comes along.
| mr_toad wrote:
| For one thing it can create paradoxes, like your future
| you deciding they didn't like where they ended up and
| stopping yourself from setting out on a journey in the
| first place.
| marcyb5st wrote:
| This is true if and only if we live in a universe with a
| time continuum that is not branching (i.e. a line).
| Instead, if we live in a time continuum that can branch
| (which will result in a directed acyclic graph) the act
| of traveling faster than light simply creates a new
| branch in which you go to the past and in that branch
| your past self never traveled.
|
| This relates to the different interpretation of quantum
| mechanics. The one that has paradoxes is the Copenhagen
| interpretation and the one with the branching is the
| many-worlds interpretation.
|
| There is also the pilot wave interpretation, but I am
| unsure how to map the example you proposed to that one.
| mr_mitm wrote:
| Branching in MWI happens when quantum systems become
| entangled, not when time travellers arrive. I don't think
| MWI is going to save you here
| irobeth wrote:
| I thought branches happened when a wavefunction
| 'collapsed' -- i.e. for every possible value of the
| wavefunction, you get a branch with a unique answer for
| 'value of the wavefunction'?
| Filligree wrote:
| The wavefunction decoheres; it doesn't collapse. Collapse
| is a function of collapse theories like Copenhagen, but
| has never been observed in reality.
|
| That said, decoherence doesn't branch time in the sort of
| absolute manner you might be thinking of. "How many
| timelines exist" is a question similar to "how long is a
| coastline"; it depends on how closely you're looking. At
| the smallest scales, 'timelines' interfere and mingle in
| a way that distinct universes really shouldn't. It's only
| once decoherence has gone well out of control that they
| can be said to be truly separate, and even then the
| interference never goes to zero, only approximately zero.
| exe34 wrote:
| it breaks the sacred timeline
| NoGravitas wrote:
| If we exist in a block universe, then all time-travel
| effects are "already" baked in. Just because something's
| path through the block isn't always "forward" doesn't
| mean it can change its path, or anything else's.
|
| In a growing block universe, I think time travel would be
| impossible, but I also think that the growing block
| universe theory is cope.
| evanb wrote:
| If causality isn't then what do you mean by 'because'?
| AmericanChopper wrote:
| This is a nitpick. The warp drive concept doesn't allow for
| FTL travel, but it could allow for you to get from point a
| to point b faster than light could.
| ImHereToVote wrote:
| This breaks causality.
| jbstack wrote:
| The idea behind a warp drive is that it utilises
| expansion of space, which is not subject to speed of
| light restrictions. The universe has already expanded
| faster than light without breaking causality.
| ben_w wrote:
| The causality violation examples I've seen in relativity
| all involved going back to where you started. No return
| trips, which includes the cosmic horizon, no causality
| violation.
|
| One question I've got though: does relativity (1) remove
| the _need_ for universal frame of reference, or (2)
| preclude the _possibility_ of a universal frame of
| reference?
|
| Because if it's the former, then (I think) FTL doesn't
| need to also be a time machine?
| rbanffy wrote:
| > No return trips, which includes the cosmic horizon, no
| causality violation.
|
| The drawback is that if a warp drive going from A to B
| leaves expanded space in its wake, a return trip will
| take longer than light would take to make a round trip.
| At the same time, an observer on B looking in the
| direction of the ship will see a shift to blue until the
| ship arrives, and, then, would see a marked shift to red
| when observing A.
| Filligree wrote:
| Nothing in specific would stop you going _around_ the
| Krasnikov tube, however?
| dustingetz wrote:
| https://en.m.wikipedia.org/wiki/Closed_timelike_curve
| K0balt wrote:
| Causality is not robust, and you can prove it to yourself
| with three sheets of light polarizing gratings. When we
| figure out how to put probability hooks on things other
| than photons, it's going to get rowdy.
| cherryteastain wrote:
| Afaik, if we introduce a special frame of reference (e.g.
| the cosmic microwave background frame) and this special
| reference frame is the only frame in which FTL is
| permitted, FTL does not violate causality
|
| See https://physics.stackexchange.com/questions/203708/can-
| ftl-c...
| quotemstr wrote:
| That's a fascinating thread. Thanks for the link.
| marshray wrote:
| Would they allow a reactionless drive?
| Rhapso wrote:
| There is "ftl" then there is "reactionless" then there is
| "doing better than the rocket equation"
|
| We will take any of it.
| taneq wrote:
| Three, because also that their warp drives fail. :D
| rbanffy wrote:
| Or it's just them hitting the brakes hard.
|
| I'm suddenly terrified advanced species capable of FTL travel
| would have Starfleet levels of shoddy engineering. A
| Kardashev type 3 is always one idiot away from destroying the
| universe.
| m3kw9 wrote:
| You have 2 things that have not been discovered/invented yet and
| you go and simulate how one fails
| snakeyjake wrote:
| Every single second spent 'studying' warp bubbles is a second
| wasted. A dollar misspent. A CPU cycle squandered.
|
| "How do you move the warp bubble?"
|
| uh... uh... uh... uhhhhhhhhhhhhhhhhhhh... this paper's title is
| sexy and will get me published!
|
| Even string theory is better than this nonsense.
| groby_b wrote:
| What interesting research are you currently pursuing? Would
| love to read the papers!
| snakeyjake wrote:
| 15 years ago I played a small, insignificant but still
| important, role in saving Hubble: https://ntrs.nasa.gov/api/c
| itations/20080023344/downloads/20...
|
| Now I design sensors that go on things designed to kill
| Russian soldiers in Ukraine.
|
| I am very confident that what I have done has been a tangible
| net benefit to humanity and is not the modern-day equivalent
| of spending time and money on the study of Orgone Energy.
| snapcaster wrote:
| So you were helping kill people who you've never met but
| bashing on the dudes studying warp drives? Not even saying
| you're a bad person but stones and glass houses man
| snakeyjake wrote:
| >So you were helping kill people
|
| Not were, am.
|
| My sensors are also good at quantifying sea level
| changes, measuring shore erosion, determining plant
| foliage density and water content, and can find ancient
| buried ruins given the right conditions so it's a win-win
| for all of humanity!
| snapcaster wrote:
| How is it a win/win unless you value human life of
| russian people at 0? Would you say that to the face of
| the victims of your work? Do the russians you help kill
| not have families and partners? Are they any more at
| fault than the average american was for Iraq?
| coryrc wrote:
| I would value their lives as negative. Lots of people
| have lives of negative impact, like Thomas Midgely Jr or
| the Russian people carrying out genocide in Ukraine.
| groby_b wrote:
| Thanks for sharing (I really meant the "I like reading
| interesting papers" request).
|
| In an odd coincidence, that means you're the second person
| I met this month who helped save Hubble.
| swid wrote:
| You make the bubble after you are already moving in the
| direction you want to go. The bubble will keep moving. What
| else would it do? Out of all the questions, this is not a hard
| one...
| ben_w wrote:
| That answer has always bugged me.
|
| In relativity, observers only agree on motion at exactly c,
| so the idea that a warp drive speeds up normal motion...
| feels like a contradiction.
|
| But then, I know I can't fully grok the relatively simple
| maths of SR, let alone GR.
| snakeyjake wrote:
| Precisely!
|
| You get it!
|
| If you have to spend the entire combined annual energy output
| of all of humanity getting up to speed, why convert the
| equivalent of 1% of the mass of the sun into energy to create
| and maintain a warp bubble?
| KingOfCoders wrote:
| There is zero evidence for aliens, still people believe in them.
| And millions and millions are wasted in the search. Just because
| neon green elephants are and seam possible, doesn't mean there
| are any. In fact, there are none, except we create them.
| ViktorRay wrote:
| The universe is so fast. Why are you so certain that life only
| evolved on our planet?
|
| When you say "there are none" it seems you are making a more
| unbelievable statement than the people who say aliens exist.
| tgv wrote:
| TBF the comment says that there's no evidence, not that there
| are none. And indeed, the belief in extraterrestial aliens is
| much, much bigger than its theoretical underpinnings warrant.
| KingOfCoders wrote:
| Indeed, especially as 85% of atheists in the US believe in
| aliens. With zero evidence, no signs, nothing.
| ViktorRay wrote:
| The parent comment literally said:
|
| _"In fact, there are none, except we create them."_
|
| I was saying that the claim that life in this universe only
| evolved on our planet is more extraordinary than the claim
| that life evolved elsewhere.
|
| So the parent comment's claim that "there are none" would
| be a belief that is actually bigger than the belief that
| there are.
| postalrat wrote:
| It's the biggest and most important question we can answer.
| elphinstone wrote:
| The amount of tax dollars to SETI vs. amount given in bank
| bailouts in various crises is orders of magnitudes different,
| setting aside historic and scientific importance.
| KingOfCoders wrote:
| Would you be fine with the government spending millions of
| tax dollars in the search for god?
| suzzer99 wrote:
| 2 trillion galaxies in the observable universe, each with 100s
| of billions of stars on average. How weird would it be if life
| only arose _once_ out of all those chances?
| dudinax wrote:
| We don't know.
| KingOfCoders wrote:
| There are 21 sextillions grains of sand on earth. One of them
| MUST be the shape of my face. This is not science, this is
| religion.
| Saigonautica wrote:
| A more accurate analogy would be that without looking at
| very much sand, you already possess one grain of sand in
| the exact shape of your face. This spikes your curiosity
| and you ask: What are the chances of finding another?
| KingOfCoders wrote:
| I do think these are two different arguments.
|
| 1. Aliens can exist because we exist
|
| 2. Aliens do exist because of probabilities
|
| Mine was about 2
| suzzer99 wrote:
| I think it would be orders of magnitude more astounding
| if aliens didn't exist than if they did, just given the
| sheer odds of life only happening once in the observable
| universe. That's all I'm saying.
| mtlmtlmtlmtl wrote:
| Holy straw-man.
| KingOfCoders wrote:
| Funny, no-one said straw-man when I had these discussion
| in philosophy studies at university. Looks like there are
| different people on HN than those studying philosophy.
| Learned something!
| snapcaster wrote:
| There probably is one though right? depending on how you
| define similarity
| thrance wrote:
| You can't know, that's the thing with having a sample of n=1
| (Earth). You can't deduce anything.
|
| There are no evidence for any alien civilizations. If they
| existed, you'd expect them to have a great impact on the
| space around them, just like we had a great impact on our
| planet. Destroying stars to get the hydrogen, building
| megastructures, shaping galaxies... Yet, we see nothing
| unnatural in our neighborood.
| suzzer99 wrote:
| I can't know what? That there are ~200 sextillion stars in
| the known universe? I'm not saying I know there's life out
| there, just that it would be pretty amazing if something
| only happened once in 200 sextillion opportunities.
|
| It's very possible intelligent life destroys itself fairly
| quickly after becoming industrialized. It's also possible
| that the technical challenges of doing something at a
| galaxy scale where we could see it from millions of light
| years away are insurmountable.
| thrance wrote:
| I meant you can't know wether it's weird or not, n=1.
|
| Personally, I believe life is extremely rare. The more I
| learn about geology and biology, the more I think Earth
| and the Solar System are very special, and life appearing
| spontaneously is nothing short of a miracle.
|
| Now, my crackpot theory: I believe that if there are
| aliens civilizations out there, they are so far from us
| that the light from their achievements has not reached
| us. And if it had, then they would be here already,
| because they travel at roughly the speed of light in
| every directions. They would have colonized Earth, which
| would have prevented us from appearing. Thus why we can't
| see any aliens in the night sky.
| suzzer99 wrote:
| I think life is extremely rare too. But 200 sextillion is
| a big number.
| negativelambda wrote:
| Here is the paper: https://arxiv.org/abs/2406.02466v2
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