What no one has seen before: gravitational waveforms from warp drive collapse
arxiv.org
arxiv.org
They derive an equation for estimated strain as a function of distance from the warp bubble collapse. How does strain translate to sound intensity, in the situation where a gravitational wave is driving sound pressure waves, and/or directly wiggling eardrums?
The skull shouldn't be able to resist gravity waves any more than soft tissues or 10km of lead?
The hull and all other parts of the ship or suit around the eardrums would all also vibrate.
GP specifically said "hear things explode in space".
1. I asked "how powerful" such waves would have to be to be audible.
2. I directly linked to another question whose accepted answer said "these waves can wiggle your ear drum"
3. Got my question closed as a duplicate but the link was to different question that only asked "is it possible" (and accepted the answer "yes") without there being any answer to the "how powerful" part.
4. Got an answer which said "no, never".
Of course, I can now get an infinite supply of confusing contradictions from ChatGPT, and because I ask questions from a position of ignorant curiosity, I'm equally incapable of discerning which of the mutually incompatible responses I get is definitely incorrect regardless of if it comes from an LLM or a trained physicist.
At one point SE was my most used resource. As of now I haven't used SE at all for I think four years. Why would you, when so much of the site's content is outdated and the moderators enforce that situation?
I even checked to make sure I wasn't misremembering things - here's someone complaining about the same thing in 2011: https://old.reddit.com/r/programming/comments/cm02a/you_cant...
The situation now is also much worse than it was, because answers could be two years out of date then and beyond a decade out of date now.
I quit when I realised I would be scrolling by walls of jQuery answers for the foreseeable future if I kept using the site, not worth the waste of my time.
Afaik, this is the policy since day one. It was aimed to be a FAQ site -- not just a question-answer site.. That's why it have community answer, allow the same poster answering his own question, encourage duping, allow other people to update/correct an existing answer,etc.
Back in those days:
1) Moderator knew the subject.
2) Most questions are "frequent" enough to qualify as FAQ.
3) When duped, the old answer is less likely to be outdated (because the site was new)
Gravitational waves obey the inverse-square law much like most radiation does (and subject to some constraints about weird spatial geometry, but most of their propagation is going on in open flat-ish space, so we can ignore that).
GW150914, the first gravitational wave observed, had an amplitude of about 4 times 10^-22 [1], i.e., differences changed by a factor of about that. Typical sound displaces the eardrum by on the order of half a micron or so [2], with the threshold of hearing at about 100 nm. The inner ear's shape is curved, but linear length is on the order of 10 mm [3] (it curves around so the total length is longer, but the gravitational wave would be transverse along its length).
A 100 nm displacement on a 10 mm length is a relative change of (100 x 10^-9) / (10 x 10^-3) = 10^-7, that is, 4 times 10^-17 times larger than the gravitational wave detected. That gravitational wave was emitted at a distance of about 410 Mpc [1], and so we can solve:
(d / 410 Mpc)^2 = 4 x 10^-17
d^2 = 4 x 10^-17 * (410 Mpc)^2
d = 2 parsec.
Granted, this is at the limit of hearing for a very brief sound (the sound was only in the human audible range for about a tenth of a second). You'd need to be perhaps 10 times closer - about 20,000 AU - for it to be a loud sound under these assumptions.
Of course you wouldn't be around to hear it for very long because you're 20,000 AU from one of the most energetic events in the cosmos, but hey, you'd hear a brief "click". Totally worth being vaporized.
[1] https://en.wikipedia.org/wiki/First_observation_of_gravitati... [2] https://biology.stackexchange.com/questions/79963/how-far-do... [3] https://www.verywellhealth.com/inner-ear-anatomy-5094399
There is also a typo in my post where there's 10^-7 instead of 10^-5, but the calculations are done correctly.
That corrected assumption gives:
d_audible / d_actual = 4 x 10^-17 x 410 Mpc = about 500,000 km
or about the distance to the Moon.----
<rest of post deleted since it was based on an incorrect premise>
For other readers, this poster's correction is right, here's an astronomy SA thread on it. https://astronomy.stackexchange.com/questions/34761/why-does...
I swear, the one time I try posting outside my areas of expertise :D
> 10^-7, that is, 4 times 10^-17 times larger than the gravitational wave detected
which doesn't sound right. (Like saying "X is 0.1 times larger than Y" when X = 10Y.) The ear displacement is 2.5×10^16 larger than the gravitational wave, no?
(Also I think 10^-7 should be 10^-5 in the quoted phrase, as per your reply above.)
Yeah, you're right, I had a typo in one of the intermediate numbers (the rest of the calcs used the correct number). Turns out I was just wrong overall though, not because of a typo but because of an incorrect assumption. Energy goes as 1/r^2, but amplitude is only 1/r, so the correct value is much smaller (it's about the Earth-Moon distance).
> 10^-7, that is, 4 times 10^-17 times larger than the gravitational wave detected which doesn't sound right. (Like saying "X is 0.1 times larger than Y" when X = 10Y.) The ear displacement is 2.5×10^16 larger
A is 2.5x10^16 larger than B is equivalent to B is 4x10^-17 larger than A, although I get what you mean by the phrasing being weird. "times the size of" would've been better than "larger".
Agree. We should list of all kinds of similar endeavors. I volunteer to be dropped at PSR J0108-1431
But as noted in other posts the post you're replying to was based on an incorrect assumption - there's a corrected value in one of the comment threads, and the distance for it to be audible is much closer than originally posted, roughly the Earth-Moon distance.
The idea of asking an LLM to generate code for a more rigorous but still high-level language is under-explored. This way you can experiment with AI - but at least have an intermediate code artifact that you can review and test before it gets published! Exposing the raw token stream is reckless.
I had never heard of "spherical cow" science before but I love the imagery.
For anyone else: https://en.wikipedia.org/wiki/Spherical_cow
Meta reference: https://xkcd.com/1053/
> They just make plausible-sounding things up, even if sometimes they're correct.
This is indistinguishable from my experience described above.
People often add more facts to Wikipedia and complain when they get deleted. The misconception is that wikipedia is where facts go, whereas, Wikipedia is specifically trying to be a tertiary source, where all the facts can be traced back to primary sources and all the analysis can be traced back to secondary sources.
People often complain that Debian testing gets almost no updates at all for six months every two years. The misconception is that it's a general rolling release distro, whereas, testing is specifically trying to become the next stable release and needs to have a freeze period.
People often complain that stack exchange deletes their questions. The misconception is that it's a site to ask a question and get an answer, whereas, stack exchange is specifically trying to produce a 1:1 mapping between specific questions and answers.
There's a saying in business that "you're not in the business you think you're in; you're in the business that your customers think you're in". If any of the above wanted to pivot, into what their less-informed users think they are, they'd do great at it, but their (sometimes inconvenient) organizational goals are what produces the high quality that made them all popular in the first place.
Agree with everything you said in general, but you lost me at the very end in the context of this thread. Hard to equate Stack Exchange as a "high quality" destination. It was probably true in the first few years after inception, but years of tug war between "the business they think they're in" vs. "the business their users think they are" have made a terrible experience for said less-informed users.
When given an alternative (e.g. LLMs, ironically probably trained on their own content, but without the snarkiness and self-righteousness of their mods), users seem to be voting with their clicks [1].
[1] https://meta.stackexchange.com/questions/387278/has-stack-ex...
Plainly not true for either Wikipedia or Stack Exchange. The rules came later, once the rules lawyers showed up to help everyone understand that those sites needed to change because they were too useful for people. This might be ancient history, but the debates that raged on for the Wikipedia editors are important. There were people who thought Wikipedia should be what we all think it should be, and they'd been there since the beginning... but they were more interested in adding missing content to Wikipedia. The exclusionists though, who to a much lesser degree hadn't been there since the beginning, thought it more important to be more prestigious than Britannica, a paper encyclopedia, for their own egos or something. And they formulated rules that they believed would get them there. And more or less the same thing with SE, though it's a private business and less a open source project than Wikipedia. Every once in awhile you'll find a 15 or 20 year old question/answer, and you'll be gobsmacked by how just "nice" it was. There was room to go off topic a little, room to provide solutions rather than answers, and so on. Though, many of those are getting deleted now days. Wouldn't want the replicants to get any ideas about how SE is supposed to work.
The disconnect is that when the core group of users was much smaller, those places acted to some extent like a real world community of people, even if no one knew anyone and no one recognized anyone else's face. Because they were a community, people wanted to be helpful. If someone had a question that was difficult to find the correct wording for, others were willing to interpret and answer the interpretation. They really wanted to be helpful. But now the group of users is much too large, and instead of wanting to be helpful, they want to compete. No one can rack up 400,000 reputation being helpful. They can't rack that up if others are being helpful. And it doesn't feel like a community, so they don't ever feel like they should be helpful.
Lately, on the science fiction stack exchange, they've been opening new questions that are duplicates, then closing my old questions/answers as the duplicate, so they can point farm their own newer ones that naturally get more traffic while making sure mine are dead and can't get more upvotes. When you check dates, mine are all timestamped years before theirs.
I do remember the day Stack Exchange was announced (on reddit maybe), and I thought to myself how great it would be compared to Expert Sexchange... little did I know.
My brain doesn't seem to index many examples of my own wrongness, even though I have more than once thought "this would be a good mistake to remember", and the worst that I can remember is under an NDA (very confident and very wrong), so the only example I can give is a currently ongoing personal error:
I've spent the last 5 years improving my German substantially, but the whole time I've been trying to estimate my current skill level and gotten the same answer, B1.
Humans have a tendency to over-value their personal experience and cite their limited knowledge sets, beliefs, and intuitions as fact, and will probably tend to only show you the info that aligns with that.
I guess I'm biased, but for the most part, I don't think the error rates between people and LLMs are significant enough for me to want to deal with the human ego, versus an AI with infinite patience. There are certainly equally intelligent and gracious people, but I don't think they hang out much on Stack Exchange (or much of the popular internet, really)
Would the eardrum be "wiggled" in the same way as a normal mechanical wave? Does the gravitational wave apply force on the eardrum?
Can I touch a gravitational wave and feel it?
That's one of the few situations where some good expospeak can make things better. If it's established the FTL travel is specifically audible in that universe because of some gravitational eardrum-wiggling snenanigans, it would just be a perfectly valid, probably quite interesting mechanic in that universe.
So there would have been room for hard SF space opera authors to sell the idea, like Stephen Baxter, Peter F Hamilton, or Alastair Reynolds.
Granted, it's amazing that now we can actually /simulate/ the sound of arriving warp ships! I imagine this will very quickly show up in short stories!
That reminds of a considerably softer-sci-fi plot device from Earth by David Brin, where (somehow) gravitational waves of the right "tuning" could kill humans (via some kind of Roche-limit or spaghettification phenomenon) but not most other living things.
Pretty sure this is only true if the spaceship (or the disturbance it causes) is ~100 miles across, like neutron stars and black holes are. If it’s much bigger or smaller, the frequencies will be shifted correspondingly shifted.
It seems rather obvious in hindsight that should it even be possible, we will clearly be able to detect warp signatures far before we would be able to build a machine capable of producing them.
This is likely not helped by the fact that we are more than halfway out to the edge of the galaxy, in one of the Milky Way's spiral arms; since we're not near the galactic centre, there are less possible travel paths that pass by us (if we just assume arbitrary random travel between any two points.)
So even if it is happening right now in abundance, and even if we can detect its occurrence, are any of those paths close enough to us to be detected?
We’re in the crystal-radio stage of gravitometrics.
But yeah, we've gotten a lot better at rectifying too.
And we can't really detect radio signatures yet, not farther than closest stars. Perhaps when we get solar gravitational lens telescopes.
For that reason, only warp drive harnessing star-equivalent energy levels would be visible at distance of stars and so-on. I mean, Fermi's observation comes down to "there's no intelligent-being signature at the star-levels of energy we can see". But that could be because: intelligent beings are rare or because harnessing star-levels of energy is hard or impossible no matter how advanced a society gets or advanced societies have no need for such harnessing or because advanced societies follow the paranoid "dark forest" logic.
Giving shits about things is one of the big reasons we have wars and other potentially civilization-ending possibilities.
Even if we are able to put 100 humans on a spacecraft for 100 years hurtling across the galaxy I'm pretty sure they'll start fighting among each other after 2 years. It's one of the reasons that I think we'll need to make embodied AGIs that are less prone to fighting to continue the legacy of civilization long term.
If there is no expansionist species, after a time one will emerge due to mutation over time.
Look at humans - there were a bunch of other intelligent species around the time humans came to the scene - we out expanded and outcompeted all them.
Now of course this is just a sample of 1. But also seems kind of inevitable. So if mutation and natural selection are the only way for an intelligent life to emerge, it would probably also be expansionist, just by virtue of outcompeting everything else. And thus would naturally want to “explore” for the sake of it - just like humans.
Of course there might be other ways to achieve intelligence- like it being developed by other species (AI). But same rule still apply. If there are more than one, eventually the one that wants to expand will expand more than the others that don’t…
And even if the species found a way to “change themselves” to make them not give a fuck, by a virtue of change being possible eventually you’ll get expansionist “strain” again.
For such a species, there would likely be no selection pressure towards such a trait. I suspect it's actually the opposite: being less expansionist could have enough benefits that it would become widespread entirely through random mutations.
Infinite growth isn't possible, desirable, or even "natural".
Sci-fi got it both ways.
Even in the eponymous "warp drive" sci-fi: Star Trek, The Federation's Prime Directive states that uncontacted civilisations are not to be contacted until they are capable of initiating contact themselves.
Usually this is by that civilisation achieving warp drive capabilities (which would allow that species to meet other species) but it can also happen with a species achieving subspace (faster-than-light) communications (which would allow that species to overhear or talk with other species).
Now we need a team of smart folks to identify tearing or other processing anomalies in universe-scale simulations.
Just off the cuff; We are predicting a soul upload technology with Neuralink etc. So an alien technosignature could look like: https://en.wikipedia.org/wiki/21_grams_experiment
This one is not rigorous but there are lots of other possibilities of this pattern.
[0] https://en.m.wikipedia.org/wiki/Phrases_from_The_Hitchhiker%...
Well, no. One of those is ordinary (“commonplace or standard”). We just don’t know which.
cute
> The crew thanks the creators and actors of the Star Trek universe for their inspiration for this work.
Interesting...
> As discussed above, for a 1km-sized ship, the frequency of the signal is much higher than the range probed by existing detectors, and so current observations cannot constrain the occurrence of such events
And yet, you still chose the word ;)
So, how big are the ships, as a kindness for readers such as myself for whom the exercise should not be left?