19 ms·
Every proton would have the energy of a baseball. It's bananas. Granted, space is really empty, but it's not that empty, somewhere around a hundred atoms per cu
by MilStdJunkie 3y ago
Every proton would have the energy of a baseball. It's bananas. Granted, space is really empty, but it's not that empty, somewhere around a hundred atoms per cubic meter. Your ship might look like a very, very long shooting star. Probably dialing the speed down a touch would be worth it for whatever your shielding material is, but who knows? We're talking miracle engines here. I think in the "Valkyrie" ship-on-a-string concept, they had some sort of magnetic thingummy that generated more power as more stuff smacked into it, then as they decelerated they let out this sort of gas mist to go ahead of the ship and smack into things.
- foota 3y agoThese regenerative braking schemes are getting out of hand.
- robertlagrant 3y agoI like that old Arthur C Clarke novel, The Songs of Distant Earth[0], where they travel with an ablative shield in front made of ice, and they can make new shield segments by finding planets with water. [0] https://en.wikipedia.org/wiki/The_Songs_of_Distant_Earth https://en.wikipedia.org/wiki/The_Songs_of_Distant_Earth
- slowmovintarget 3y agoAlistair Reynolds also used this in his ship designs.
- M_bara 3y agoPushing ice… a brilliant book - my first foray into hard sci-fi
- jcul 3y agoI read project hail Mary over Christmas, and they deal with this problem too. Though I can't say much without giving away spoilers. A great read if you are a sci-fi fan!
- e40 3y agoMy second favorite sci-fi book of all time. Three body being the first.
- satvikpendem 3y agoIndeed. Have you read the rest of the series? It just gets crazier and crazier.
- jcul 3y agoThe rest of the hail mary series?? Or Three Body? I have read two of the three body books, but I wasn't aware of a sequel to project hail mary, would be very excited if that's the case!
- satvikpendem 3y agoThe rest of the three body problem series.
- jcul 3y agoAh got you, I think I still have one more to read.
- e40 3y agoYes, the trilogy is really a unit for me. Books 1 and 2 are really a single story. Book 3 is different but amazingly great.
- satvikpendem 3y agoI recommend the audiobook in particular for this book.
- The_Colonel 3y agoI think Hail Mary (and Astronaut) is more suited for people who don't usually like sci-fi.
- whimsicalism 3y agowhy are protons more likely to be closer to rest relative to earth than relative to the fast spaceship?
- schiffern 3y ago"Although the density of atoms in the interstellar medium is usually far below that in the best laboratory vacuums, the mean free path between collisions is short compared to typical interstellar lengths, so on these scales the ISM behaves as a gas (more precisely, as a plasma: it is everywhere at least slightly ionized), responding to pressure forces, and not as a collection of non-interacting particles." https://en.wikipedia.org/wiki/Interstellar_medium https://en.wikipedia.org/wiki/Interstellar_medium
- actionfromafar 3y agoBecause the entire Milky Way is mostly at rest relative to itself. If you are charging full speed ahead into its center, you are going against just about everything, including energetic particles no doubt coming the from the crowded center of the galaxy.
- dfee 3y agoI’d like to see a map of the known universe visualizing atomic density on a log scale. I’d never seen “a hundred atoms per cubic meter”, but it’s always been my intuition that, without some quite interesting shielding, you couldn’t make it anywhere near the speed of light. And on the other hand, I’ve seen claims that “space is really big” as you mentioned; but that claim has always seemed dubious.
- wongarsu 3y ago100 atoms per cubic meter is on the lower end of typical densities in the interstellar medium. It can get many orders of magnitude denser than that. Outside galaxies you have better chances of surviving high speeds. The intergalactic medium is only 1-10 particles per cubic meter in the web of gas we call the warm–hot intergalactic medium, and possibly less outside of that.
- micw 3y agoSo would probably better to get out of the galaxy disc, travel -fast- to the other end and dive back into rather that go straight through the galaxy?
- wordpad25 3y agoExcept we can't get to edge of the galaxy quickly. I guess Hitchhikers guide to the galaxy building space highways destroying everything in the way could be more than a gag after all.
- ben_w 3y agoGo up and over, that's only a few hundred light years. To the edge of the disk is 30,000.
- eru 3y ago> I’d never seen “a hundred atoms per cubic meter”, but it’s always been my intuition that, without some quite interesting shielding, you couldn’t make it anywhere near the speed of light. It's not that bad. With currently known science, your fuel would most likely be hydrogen so you can run a fusion reactor. The rocket equation tells you that most of your starship by mass would be fuel, if you want to go fast. Of all the stuff on your ship that's not fuel, you'd probably need quite a bit of water for survival needs. So you would make your spaceship relatively long and thin (to maximize internal volume for a given frontal area), and you would store your fuel (and water) in front of you to serve as exactly that shield.
- abhibeckert 3y ago> Every proton would have the energy of a baseball I wonder if you could capture that energy and use it to generate thrust. Most of the energy is coming from your thrust so it'd be a lossy process however if you're able to capture all of the energy then there won't be anything left to damage the ship.
- function_seven 3y agoIsn't this kinda like mounting a fan on your car's roof to charge the battery? You have accelerated your spaceship to 0.995C (or whatever) and now you are encountering space dust at a phenomenal rate. Some of that dust is moving away from you, some of it toward you, some of it is at rest. On average it's all just sitting there unaware that your vessel is about to smack into it. The energy is in the difference between your speed and the particle's. If you try to harness it, you slow down. (I'm asking genuinely here. My analogy might be wrong because it's too classical!)
- zardo 3y agoI think in principle you should be able to generate thrust greater than drag orthogonal to the particle flow. That's what wings do.
- amelius 3y agoThis is a bit like driving into a brick wall, and then asking if you could use the released energy to go faster ...
- sveolon 3y agoImagine you drive into a wall of tnt, break through it, and as you exit it explodes and gives you an extra boost. Yes, you’ve lost some speed at the beginning but you’ve gained much more
- _factor 3y agoThe tnt has potential energy. The only reason those protons have energy is because you’re smacking through them with energy you’ve already found.
- GuB-42 3y agoEven if you managed to avoid matter, at some point, photons will start to become a problem. As you continue to accelerate, eventually, the cosmic microwave background itself will become deadly X-rays.
- antihipocrat 3y agoWould a layer of water in the forward hull positions mitigate this?
- mr_mitm 3y agoTo a point, sure. Lead would be better. Some joke that this is the reason why Klingons have these thick foreheads.
- xattt 3y agoX-ray sources would turn to gamma rays. Not that it’s any better that X-rays. Other comments suggested lead plates. It would quickly get irradiated and would probably need to get shed as soon as you got to a destination.
- wnkrshm 3y agoNo accounting for particles yet, which you'll also keep hitting, making your ship's materials radioactive and causing lots of secondary particle showers, bremsstrahlung and the likes.
- ben_w 3y agoFirst the particles will act like radiation, then they'll start causing matter-antimatter pair creation with your hull, then you'll get some exotic heavy quarks popping into existence, then you'll get some Higgs particles forming and at some point questions like "what is the mass of my ship" stop making sense.
- LorenPechtel 3y agoNo--x-rays will not make anything radioactive. Gamma rays can only do so when they're in the 2GeV range or higher (indirectly, through pair production.) It's particles that make things radioactive, mostly neutrons as they aren't repelled by the nucleus and thus have a much easier time getting in. And while it would be hard to construct a shield out of it helium is effectively immune to becoming radioactive under neutron bombardment. And while lead isn't immune the reaction sequence produces nothing that won't be contained by the lead and it self-regenerates, enough bombardment returns it to where it started.
- TaylorAlexander 3y agoWhat do you mean “the energy of a baseball”? A baseball at what speed?
- moosedev 3y agoI assumed they meant a baseball at baseball speed.
- arethuza 3y agoRather than relativistic speeds, which would be bad: https://what-if.xkcd.com/1/ https://what-if.xkcd.com/1/
- mlyle 3y agoThey're saying a fastball pitch-- 340 joules or so of energy. The thing is, you need to be going implausibly fast to have a proton have a fastball level of energy. Even at .99999999 C, a hydrogen atom still has less than a microjoule of energy. You need a lot of 9's to get up to 340 joules. 1/sqrt(1-(0.99999999)^2) * (1 atomic mass unit * (speed of light)^2 1.05529895 × 10-6 joules
- idiotsecant 3y agoI feel like regardless of the exact speed of the baseball, that's somewhat more energy than a typical proton.
- j4yav 3y agoA baseball at football speed, of course
- heads 3y agoIf you’re doing 2e8 m/s, your ship is long and thin with a 1m3 nose cone, and space has 100 baseballs per m3 then you’re being hit by 2e10 baseballs a second. How do I get an idea for what 20 billion baseballs (2TJ) feels like? Apparently bullets are about an order of magnitude more energetic than baseballs (800J vs 80J) so I guess I could try to build my intuition based on being shot ~2 billion times a second instead. A kiloton of TNT is 4GJ, so it’s also like a 500 kiloton bomb going off every second. Dropping 5e5kg of rock into the worlds biggest dumpster truck at 10m/s yields 25MJ of chaos so it’s also like a parking lot of 80,000 of those being filled with a continuous stream of rubble. That’s probably the best analogy given that we’re talking about machinery — your spaceship needs to have the build resilience of tens of thousands of dumpster trucks but condensed into the cross sectional area of a dinner table.
- kaashif 3y ago> A kiloton of TNT is 4GJ, so it’s also like a 500 kiloton bomb going off every second. Funnily, my first reaction to this comparison is that it makes it seem more plausible to me that this is possible. After all, a Star Destroyer can take gigaton level hits! But the problem with that is Star Destroyers are fictional. I've been spending too much time on spacebattles.com.
- heads 3y agoThe numbers are big but they don’t seem “big big” like Sagittarius A* is big or the distance to Andromeda is big.
- lstodd 3y agoDistance to Andromeda isn't big. Galaxy filaments are big.
- MilStdJunkie 3y agoThe canon energy levels given for Star Wars weaponry are so inconsistent with the presentation that one either ignores canon or accepts that the Star Wars galaxy has fundamentally different physics. Extreme geek caution: I've been running a Star Wars pen and paper RPG since . . oh dear. . 2015, in an ancient simulationist[1] game system, and the only way I've been able to make anything consistent is dialing everything down to WW2 levels. 7.62x5X, .50 BMG, 46 cm/45 Type 94 capital ship weapons. All except for exceptional plot items, like lightsabers and doomsday weapons, which behave . . well, they're magic. Sensors are likewise pretty primitive, enhanced with canon exotics like Kronau radiation, so engagement ranges are (relatively) piddling, hostiles zip by each other all the time. Electronics and technology in general must be barely understood by literally anyone, with the powerful assemblies - hyperdrive cores, droid motivators, repulsorlift "sand" - being exotics, possibly xenotechnology from the deep past mined by xenoarchaeologists[2], but hooked together by varying degrees of "competent 1950s electrician". In short, it's a fantasy setting with guns that players get excited about. And a community of worldbuilders that is, let's not dice words here, insane. That second point is huge if you're not 24 or otherwise gifted with a combination of hubris and spare time. [1] All the kids today with their streamlined narrative-focused games! Seriously, though, I get it. The physics simulationist in me that brings me to HERO System says more about me as a person than my players. [2] Archaeology a much more valuable degree in the Star Wars universe.
- tomtomistaken 3y agoSo such ships would look "aerodynamic"?
- defrost 3y agoMore like bridges and skyscrapers, perhaps with an ablating sheild at the lead end, maybe an electromagnetic field to divert particles away. If the thrust is high enough, a tenth of a G to 1.5 maybe, the ship has to "stand up" on the thrusting engine in the same manner as a building must stand up over it's footprint, supporting itself against the force of (artifical) gravity. If it's higher thrust (as the human meatsacks are suspended in a fluid they've also swallowed ??) then the ship has to look even more like a heavy load brutilist building.
- gattr 3y agoIt's more stable (and structurally leaner, I think) to instead have the engines at the front in tractor configuration, as in the interstellar ships in Avatar movies.
- a_gnostic 3y agoA magnetic Ramjet could help (1) 1. https://www.sciencedirect.com/science/article/pii/S0094576521005804 https://www.sciencedirect.com/science/article/pii/S009457652...
- ikekkdcjkfke 3y agoAlready patented?
- denton-scratch 3y ago> somewhere around a hundred atoms per cubic meter. Wikipedia says that intergalactic space contains less than one hydrogen atom per cubic meter; and that most of the baryonic matter in intergalactic space consists of hydrogen and helium atoms. If I've understood it correctly... https://en.wikipedia.org/wiki/Outer_space https://en.wikipedia.org/wiki/Outer_space
- aerique 3y agoYes, but that's intergalactic space not interstellar space. We've not even begun exploring the latter :-)
- meindnoch 3y agointergalactic != interstellar
- denton-scratch 3y agoWell, I don't think the discussion was restricted to interstellar space; for example there's been quite a bit of chat about how long it would take, at 1G (on the astronaut's watch) to reach the edge of the (known) universe.
- ijustlovemath 3y agoWhere'd you get 100atoms/m^3? I remember in astrophysics we learned it was closer to 1 proton/m^3, but maybe that was the universe average (which includes the vast and desolate intergalactic medium)