Post Ak7mWN1v4S3FLk0wAi by epicdemiologist@wandering.shop
(DIR) More posts by epicdemiologist@wandering.shop
(DIR) Post #AjwWQxLBQ5cKDqrUEi by futurebird@sauropods.win
2024-07-15T04:03:55Z
0 likes, 0 repeats
A "Halo Drive" is a concept for sub light speed travel that uses either a spinning black hole, or twin black holes (stationary) to accelerate a ship by slingshotting a laser around the singularity and harvesting the spin from the black hole to go real real fast. You can accelerate an arbitrarily large mass.Does that mean that one could just IDK speed up a whole moon and use it like ...ballast for a longer journey? Is there a way to convert extra mass to more speed? (not like fuel)
(DIR) Post #AjwWdOE5Hn3N56TCiG by futurebird@sauropods.win
2024-07-15T04:06:10Z
0 likes, 0 repeats
A limitation of the drive is distance. You need to get up to speed while in range of your black hole. But since you can accelerate as much mass as you want... is there a way that just taking more mass with you could be a way of having more power for later in the journey?
(DIR) Post #AjwX94cnhNnZYV8fuS by futurebird@sauropods.win
2024-07-15T04:11:52Z
0 likes, 0 repeats
@djm The black hole is stationary. You need to do all your acceleration while in range. (limited by focusing the lasers)
(DIR) Post #AjwXAYbDjvCQoF6iDg by nazokiyoubinbou@urusai.social
2024-07-15T04:11:58Z
0 likes, 0 repeats
@futurebird Well, there's always the fact that ejecting mass can allow relative acceleration.And of course that extra mass could be fuel.
(DIR) Post #AjwXCIvqxdsKnVaiNE by mcc@mastodon.social
2024-07-15T04:12:17Z
0 likes, 0 repeats
@futurebird One thing I'd worry about is *stopping* at your destination … maybe you just gotta make sure you have another black hole at the other end so you can do the acceleration in reverse. Like train terminals
(DIR) Post #AjwXDxQtrjJghKtwvY by futurebird@sauropods.win
2024-07-15T04:12:35Z
0 likes, 0 repeats
@nazokiyoubinbou What do we mean by "ejecting" does that use energy?
(DIR) Post #AjwXPxcJ0WVmk9xYzw by nazokiyoubinbou@urusai.social
2024-07-15T04:14:55Z
0 likes, 0 repeats
@futurebird I think by releasing it at just the right vector you can inherit the inertial energy? I'm not a physicist. That may be gibberish.I do know if you actually DO use energy, you can essentially blast it off, pushing the part you care about forward relative to the lost mass (albeit in a not very efficient manner.)Of course, fuel makes the most sense regardless since that gives us the highest acceleration relative to the same mass.
(DIR) Post #AjwXWGHaWNGUN8H2US by futurebird@sauropods.win
2024-07-15T04:16:05Z
0 likes, 0 repeats
@nazokiyoubinbou But mass doesn't matter when building this kind of ship, not for the initial acceleration. I'm trying to think about how this ought to alter the design... like it should be a pretty radical alteration...
(DIR) Post #AjwXi7Un17Y6av6Sbw by futurebird@sauropods.win
2024-07-15T04:18:12Z
0 likes, 1 repeats
@smitten This is starting to sound like the "near relativistic particle highway" I was thinking about before. I imagined that we'd find one of these things, but not know how to exploit it. But this gives me more ideas for how it might work... if you built it. https://worldbuilding.stackexchange.com/questions/247798/interstellar-travel-via-a-moving-walkway-of-dust
(DIR) Post #AjwXmgz310uFoiR7Z3 by claralistensprechen3rd@friendica.myportal.social
2024-07-15T04:17:31Z
0 likes, 0 repeats
"Harvesting spin". What a concept.
(DIR) Post #AjwXmi7Eo33HKPHAy8 by futurebird@sauropods.win
2024-07-15T04:18:59Z
0 likes, 0 repeats
@claralistensprechen3rd Slow down the black hole a little. Nobody will mind. It'll last for eons.
(DIR) Post #AjwXqqgAuR6p2tagy0 by michael_w_busch@mastodon.online
2024-07-15T04:19:46Z
0 likes, 1 repeats
@futurebird The amount of energy available in the "halo drive" concept is limited to the rotational or orbital kinetic energy of the black hole.There is also a limit to the total velocity change that is possible (4/3 of the orbital velocity of the black hole in a binary. I defer to David Kipping's math - https://arxiv.org/pdf/1903.03423 ).And the concept also requires converting a large fraction of the spacecraft's initial mass into light.So the overall spacecraft mass is far from the only problem.
(DIR) Post #AjwXsHFJcVVRjMhzxQ by nazokiyoubinbou@urusai.social
2024-07-15T04:20:03Z
0 likes, 0 repeats
@futurebird Right, and this is normally the problem with fuel. It is tricky because the more fuel you add the more mass you add, so a balance is often needed. This solves that problem rather nicely.I think to some extent what you're asking about might have been done on Interstellar? https://www.youtube.com/watch?v=1t73rxE5T_II believe this was also in Gateway (but I never got to that part.)
(DIR) Post #AjwYJq91yYw9mlubvk by faassen@fosstodon.org
2024-07-15T04:25:02Z
0 likes, 0 repeats
@futurebirdSpace 1999 had a whole moon flying FTL yet not faster than the moon shuttles they had
(DIR) Post #AjwYesctwZe1Z1usWu by mcc@mastodon.social
2024-07-15T04:26:45Z
0 likes, 0 repeats
@michael_w_busch @futurebird "The amount of energy available in the 'halo drive' concept is limited to the rotational or orbital kinetic energy of the black hole."Does the act of accelerating with the halo drive then *sap* rotational energy from the black hole?
(DIR) Post #AjwYetHJWJyFaMp9WK by futurebird@sauropods.win
2024-07-15T04:28:50Z
0 likes, 0 repeats
@mcc @michael_w_busch yes, well it makes it spin more slowly.
(DIR) Post #AjwYx1VheVLGKUCW00 by nazokiyoubinbou@urusai.social
2024-07-15T04:24:01Z
0 likes, 0 repeats
@michael_w_busch @futurebird Sounds like in the end it's like with the concept of warp drive and etc. The ultimate limit really is the energy we can put into it. Exotic energy is needed to truly pull it off.
(DIR) Post #AjwYx2VNxAgLPn3m8u by michael_w_busch@mastodon.online
2024-07-15T04:29:47Z
0 likes, 0 repeats
@nazokiyoubinbou @futurebird The halo drive concept does not violate the energy condition from general relativity ("the energy density of spacetime cannot be negative").The various warp drive concepts would. So would negative matter and many other things theorists have played with.
(DIR) Post #AjwYx3Wq9FRKaakS36 by nazokiyoubinbou@urusai.social
2024-07-15T04:30:44Z
0 likes, 0 repeats
@michael_w_busch @futurebird Presumably we must create the black hole first and provide it with the necessary energy for sufficient spin/etc, right?
(DIR) Post #AjwYx4Q8pdfxM6ccFM by futurebird@sauropods.win
2024-07-15T04:32:06Z
0 likes, 0 repeats
@nazokiyoubinbou @michael_w_busch If we can make black hole I think we might have better options than this maybe? We could just go to the nearest black hole... as soon as we find it. (with IDK gravity wave detection?)
(DIR) Post #AjwYzb9E7kQrR6upBA by michael_w_busch@mastodon.online
2024-07-15T04:32:16Z
0 likes, 1 repeats
@mcc @futurebird Using a spinning black hole or a black hole binary to speed up a spacecraft would slow down the spinning hole or shrink the orbit of the binary.Using it to slow down a spacecraft would do the reverse.David Kipping imagined a transportation network of starships going back and forth between black hole binaries; alternately shrinking and expanding their orbits.
(DIR) Post #AjwZ9mjtsjhGHZvWRk by futurebird@sauropods.win
2024-07-15T04:34:25Z
0 likes, 0 repeats
@michael_w_busch Can't you reuse the light as it slingshots back to you? Or will that not build up fast enough?
(DIR) Post #AjwZFb5e6ezrtGryK0 by claralistensprechen3rd@friendica.myportal.social
2024-07-15T04:34:01Z
0 likes, 0 repeats
Hokay...I could explain things or I could just post a link to an explanation, and the black hole requirement is a single black hole, spinning, or two black holes orbiting each other. There's no such thing as a stationary black hole. What's accelerated are laser photons which are expected to energize a "light sail" and the spacecraft are the size of microchips.https://www.technologyreview.com/2019/03/18/103286/a-halo-drive-could-accelerate-interstellar-spacecraft-to-close-to-the-speed-of-light/
(DIR) Post #AjwZFbzIljW4fsuQ4W by futurebird@sauropods.win
2024-07-15T04:35:25Z
0 likes, 0 repeats
@claralistensprechen3rd By "stationary" I just mean that you don't take the black holes with you. (which I've read about some ideas doing)
(DIR) Post #AjwZK2PgSfQRn3MMEa by mcc@mastodon.social
2024-07-15T04:35:16Z
0 likes, 0 repeats
@michael_w_busch @futurebird I'm sitting here trying to figure out if there's some situation where someone would use this tech not per se to speed something up, but just to bleed kinetic energy off an inconveniently placed black hole to make it less dangerous somehow (not sure that part actually makes sense). Like burning nuclear waste in a burner reactor.
(DIR) Post #AjwZK39Pie0O4sksVs by futurebird@sauropods.win
2024-07-15T04:36:17Z
0 likes, 0 repeats
@mcc @michael_w_busch You can use it for power. To run your lights and grow food, and do things.
(DIR) Post #AjwZeN53KZBdgEPBeC by belfinwe@social.linux.pizza
2024-07-15T04:39:55Z
0 likes, 0 repeats
@futurebird Seems ideal for dark forest strikes 🤔
(DIR) Post #AjwaBi34OQmAGeNI1o by nazokiyoubinbou@urusai.social
2024-07-15T04:45:58Z
0 likes, 0 repeats
@futurebird @mcc @michael_w_busch Along those lines, there was something I saw or read a while back (I think a Kurzgesagt video) where they suggested a great way to extract energy from a black hole involved I think it was lasers shined at an angle to absorb energy and frequency shift, then exit out the other end to release that energy.
(DIR) Post #Ajwb4B9YOnW6AgNeTo by michael_w_busch@mastodon.online
2024-07-15T04:55:48Z
0 likes, 0 repeats
@futurebird "Photons are recycled by the spacecraft and repeatedly emitted and re-absorbed from the gravitational mirror""This work has assumed that extremely efficient absorption of the photon is assumed by the spacecraft upon reception. An idealized system needs to be able to recycle the photons with thermal losses much smaller than the total energy transferred to the spacecraft."Among other problems with the concept as outlined in sections 4 and 5 of the paper.
(DIR) Post #AjwdqDvtZDjgbJ1rdo by vruz@mastodon.social
2024-07-15T05:26:53Z
0 likes, 0 repeats
@futurebird @nazokiyoubinbou It doesn't even need to be moonstuff, it's easier to think of this if you conceive the spaceship as a solar sail.A solar sail doesn't need a whole lot of mass as ballast.But orders of magnitude the energy of solar wind would make interstellar travel feasible.(back of the envelope calculation)
(DIR) Post #AjwkZ2C2f1W2wnKeZs by nicholas_saunders@mastodon.social
2024-07-15T06:42:12Z
0 likes, 0 repeats
@futurebird how is this not one of a #perpetualmotionmachines ?
(DIR) Post #AjwwKUOWj205WD0Dyq by futurebird@sauropods.win
2024-07-15T08:54:02Z
0 likes, 0 repeats
@nicholas_saunders The spin of the black hole is slowed down by doing this.
(DIR) Post #Ajx4dZXEdXBUb3gbk8 by futurebird@sauropods.win
2024-07-15T10:27:12Z
0 likes, 1 repeats
I think I have a solution:You use the energy from the spin of the black hole to accelerate a very large mass, but also to set it spinning on an axis orthogonal to the direction of travel. Then you can use that spin as a power source once you are out of range. So how fast could you get it spinning? I'm assuming the people on this ship would not be in the spinning part (they'd be pancaked) They would have their own habitat that used acceleration for artificial gravity.
(DIR) Post #Ajx4ltWiBzMcurPTZA by futurebird@sauropods.win
2024-07-15T10:28:40Z
0 likes, 0 repeats
The ships would have a huge spinning moon in front (as shield for particles and radiation... and power source) then a tiny ship in the back using the rotation of the moon for power.
(DIR) Post #Ajx5N2aZShqxjjvZom by tsturm@famichiki.jp
2024-07-15T10:35:22Z
0 likes, 0 repeats
@futurebird Got to be careful not to shred the moon (moonlet?) to pieces if the spin gets too fast. That would be a bad day, especially if you plan to use the spin energy to slow down at the destination.
(DIR) Post #Ajx5Zxz3tWNrDeXwhM by futurebird@sauropods.win
2024-07-15T10:37:45Z
0 likes, 0 repeats
@tsturm Now I need to learn more about just how fast something can spin before it comes apart...I just want to write a SF story but I keep getting tricked into studying physics! Which I find a little intimidating for no coherent reason.
(DIR) Post #Ajx6A2lbaZo2TiSHnU by justafrog@mstdn.social
2024-07-15T10:44:13Z
0 likes, 0 repeats
@futurebird Scarab space travel.
(DIR) Post #Ajx6QtmoEQgpY43VFw by pbloem@sigmoid.social
2024-07-15T10:47:09Z
0 likes, 0 repeats
@futurebird So... a flywheel?
(DIR) Post #Ajx6WdypuXq6GSQ8Qa by futurebird@sauropods.win
2024-07-15T10:48:18Z
0 likes, 0 repeats
@pbloem Yes. A flywheel! My understanding of physics is very 19th century ... I feel like this is probably a too primitive idea... but it's what I can imagine...
(DIR) Post #Ajx6Xzt3wn8GUsMi5g by Fischblog@chaos.social
2024-07-15T10:48:16Z
0 likes, 1 repeats
@futurebird Better don't forget that huge moon in front of you when you go straight toward an alien planet, though.
(DIR) Post #Ajx6aAODrzg5eJyUGO by futurebird@sauropods.win
2024-07-15T10:49:00Z
0 likes, 0 repeats
@Fischblog Oh this method is for going from one blackhole to another. You need a blackhole to slow down.
(DIR) Post #Ajx6g3o3GADOy7rlhI by pbloem@sigmoid.social
2024-07-15T10:50:01Z
0 likes, 0 repeats
@futurebird I don't know, even fusion reactors are still basically steam engines. Sometimes the old ways are best.
(DIR) Post #Ajx6mEZm8BMq6l8H7Q by ehproque@paquita.masto.host
2024-07-15T10:51:06Z
0 likes, 0 repeats
@futurebird maybe you can get them pancaked along one axis and spaghettified along another; not sure what this would accomplish but I'm sure the result would look funny!
(DIR) Post #Ajx900ImCNHDnesJY8 by futurebird@sauropods.win
2024-07-15T11:16:02Z
0 likes, 1 repeats
@remote_orb @Fischblog
(DIR) Post #Ajx97t7glzxlqsRreq by Fischblog@chaos.social
2024-07-15T11:17:14Z
0 likes, 0 repeats
@futurebird And, uh, then what? 🤔
(DIR) Post #Ajx99ep2uiPW4uZWs4 by janbogar@mastodonczech.cz
2024-07-15T11:17:36Z
0 likes, 1 repeats
@futurebird @tsturm If the moon is held together by gravitational force (true for natural ones I think) and if I didn't make a mistake, the max kinetic energy you can store by spinning it before peaces start to fly off is 1/3 of the total work needed to take it apart (or equivalently, gravitational energy that got turned to heat when the matter fell into the moon during its formation).So a lot.
(DIR) Post #Ajx9UcoHagElv0DHAO by futurebird@sauropods.win
2024-07-15T11:21:35Z
0 likes, 0 repeats
@Fischblog Well don't you have a chance of sending a probe that might tell future generations about other galaxies? This lets you go places as much as anything even vaguely plausible might. And I bet there are a lot more black holes than we think. We don't really have a way to look for them directly as of yet... but when we do... we could find one closer than the nearest star. It's like a high speed rail network. And we live in the boondocks. It's not ideal but it's still useful.
(DIR) Post #AjxA943BjMm9zDT4xU by janbogar@mastodonczech.cz
2024-07-15T11:26:37Z
0 likes, 1 repeats
@pbloem @futurebird even better, current research fusion reactors use flywheels to store and then quickly release the energy for each shot (i.e. ignition of termonuclear reaction). At least Compass tokamak in Prague works this way.Taking that much power from the grid is not feasible, abd flywheels are the best storage for slow buildup followed by quick release.
(DIR) Post #AjxCJ7ZTh9r5i5Uie0 by Fischblog@chaos.social
2024-07-15T11:53:04Z
0 likes, 0 repeats
@futurebird Given how far we are from reliable travel even within the solar system it's rather like early medieval Franks imagining a high-speed rail network. Valid point, though.
(DIR) Post #AjxGkuTKOHrX0b7kUi by IngaLovinde@embracing.space
2024-07-15T12:42:54Z
0 likes, 0 repeats
@futurebird @pbloem flywheels might actually be a good idea for home-scale energy storage, not requiring large amounts of rare materials with dubious origins and ecological footprint as chemical batteries do.
(DIR) Post #AjxNHGuR6XhZaWcOKu by michael_w_busch@mastodon.online
2024-07-15T13:55:59Z
0 likes, 1 repeats
@futurebird If using rotating masses for power on board a spacecraft; it is recommended to have pairs of masses that are rotating in opposite directions.Otherwise; conservation of angular momentum will keep things spinning unless you throw parts of the spacecraft off to infinity.
(DIR) Post #AjxcB4LOPK4EC0j9cG by dgoldsmith@mastodon.social
2024-07-15T16:41:19Z
0 likes, 0 repeats
@futurebird The moon can't spin very fast without falling apart. Also, you can't extract energy from a spinning moon without that angular momentum going somewhere. You’d need a moon spinning in the other direction as another poster noted.Also, the spaceship can't just "hang" behind the spinning moon. It will fall towards it due to the moon's gravity unless thrust is applied continuously, or unless it goes into orbit around the moon, in which case it's a shield only half the time.
(DIR) Post #AjxdrN1TRziEEy93ui by dgoldsmith@mastodon.social
2024-07-15T16:44:41Z
0 likes, 0 repeats
@futurebird Also if you have two moons, *they'll* fall towards each other unless they're in orbit around each other, and again you have the problem it's only a shield part of the time.
(DIR) Post #AjxdrNyJvCmfBTg3dY by futurebird@sauropods.win
2024-07-15T17:01:48Z
0 likes, 0 repeats
@dgoldsmith Back to the drawing board I guess. Though, I still think such a mode of travel ought to be possible, and it's a minor plot point. What is less believable about the story (other than the people-sized ants) is the stasis tech that makes a journey that takes 900 years possible.
(DIR) Post #Ajy5tEIHflXaSpgOeG by iDGS@mas.to
2024-07-15T22:15:54Z
0 likes, 0 repeats
@futurebird Just a “sports fan” of Science (capital-S!) but I’d be interested in any references you can point me to about using black holes to power interstellar travel.
(DIR) Post #Ajy68N2TRPpbviVWs4 by futurebird@sauropods.win
2024-07-15T22:18:36Z
0 likes, 0 repeats
@iDGS Here is a fun video on the "halo drive" https://www.youtube.com/watch?v=rFqL9CkNxXwAnd here is one on black hole ships:https://www.youtube.com/watch?v=oAocMzxPjjo
(DIR) Post #Ajy6FHeBsyJNEdRh56 by iDGS@mas.to
2024-07-15T22:19:53Z
0 likes, 0 repeats
@futurebird Thank youuuu! 🤗
(DIR) Post #Ak7aeS6wreJDyWSBtY by llewelly@sauropods.win
2024-07-20T12:12:58Z
0 likes, 0 repeats
@futurebird @remote_orb @Fischblog the moon is actually the death star, so if something is in your way, you just destroy it.
(DIR) Post #Ak7apDRviSPbgkOrhY by mcsquank@mastodon.online
2024-07-20T12:14:50Z
0 likes, 0 repeats
@futurebird would the moon just spin to pieces?
(DIR) Post #Ak7atlko7B4VExOvHE by petealexharris@mastodon.scot
2024-07-20T12:14:59Z
0 likes, 0 repeats
@futurebird @remote_orb @Fischblog This is definitely in the category of megaprojects that can only be achieved by being so busy working out how to do it that nobody asks why to do it.
(DIR) Post #Ak7bdwIRFaWXG39C2i by alec@perkins.pub
2024-07-20T12:23:58Z
0 likes, 1 repeats
@futurebird who needs a spaceship when you can just take your whole planet? Maybe you can bring a small star with you for warmth? (Dang this sounds like awesome worldbuilding for a Doctor Who episode)
(DIR) Post #Ak7cAkPWSil1x26ZTU by dn_mason@mas.to
2024-07-20T12:29:58Z
0 likes, 0 repeats
@futurebird So that's how he managed the Kessel Run in less than twelve parsecs(from the arxiv preprint here: https://doi.org/10.48550/arXiv.1903.03423)
(DIR) Post #Ak7mWN1v4S3FLk0wAi by epicdemiologist@wandering.shop
2024-07-20T14:25:58Z
0 likes, 0 repeats
@futurebird So, like a flywheel?
(DIR) Post #Ak9d8GewauHTN1cTFg by alec@perkins.pub
2024-07-21T11:50:10Z
0 likes, 1 repeats
@futurebird I woke up thinking about this still, and how it lets Ptolemy be right about the solar system. The Earth has an artificially small star orbiting it, plus several flywheel moons (planets) rapidly spinning with the halo lasers on them. The moons are used as gravity tugs to steer the planet on a particular trajectory past the black hole so it can get flung in the desired direction.
(DIR) Post #Ak9dGS6nuSohCFYNZA by futurebird@sauropods.win
2024-07-21T11:51:43Z
0 likes, 0 repeats
@alec 🤯