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If we could solve the energy problem, humans could go pretty much anywhere in the galaxy on a 1G ship. (ok there are other issues like actually building the shi
by Johnny555 5y ago
If we could solve the energy problem, humans could go pretty much anywhere in the galaxy on a 1G ship. (ok there are other issues like actually building the ship, supplies (or a biosphere that can support life for decades), shielding, but that's all easier with unlimited energy).
For example, a ship could travel 1,000 light years to the Orion Nebula in only 15 years (as perceived by those on the ship). And since they are living in 1G, a lot of the detrimental effects of long-term space travel are eliminated.
Of course, to an observer on earth the trip would take over 1000 years, so don't expect to hear how the trip went.
- nerpderp82 5y agoIf you take your whole civilization with you, it doesn't matter how fast or slow you go, you are already where you need to be.
- coderintherye 5y agoCivilization is a believed concept. Physically taking all of your people with you does not equate to maintaining civilization.
- ryandrake 5y agoThis thread is reminding me of one of my favorite Clarke books, which partially explores this theme: The Songs of Distant Earth [1]. Is there such thing as a singular human civilization, once it become split by great distances and millennia? 1: https://en.wikipedia.org/wiki/The_Songs_of_Distant_Earth https://en.wikipedia.org/wiki/The_Songs_of_Distant_Earth
- rbanffy 5y agoIt’s an excellent book. Mike Oldfield made an excellent soundtrack for it, and Clarke wrote the insert for the disk.
- nerpderp82 5y agoHumanity will diverge as soon as we have off Earth reproduction.
- robotresearcher 5y agoWe are there right now, zipping through space together. We have some social problems and some HVAC problems. But the vehicle is already underway.
- nerpderp82 5y agoYou might enjoy this video on terraforming Venus, https://www.youtube.com/watch?v=G-WO-z-QuWI https://www.youtube.com/watch?v=G-WO-z-QuWI I think we should consider the whole solar system our galactic ship while making sure to keep the current habitation quarters in top notch shape.
- generalizations 5y agoWhich, to me, is why we should be focusing on new ways to produce energy. Solar and wind is nice, but we could revolutionize humanity and save the earth if we found a way to build cheap energy sources with a density of gigawatts per cubic yard. What better way to save the earth and solve the population problem than to have the energy production capabilities to simply build e.g. ringworlds? Even that's not out of the realm of possibility with that kind of energy available.
- ant6n 5y agoI’m a little confused. Are you proposing to Save this world, or build/settle others?
- Robotbeat 5y agoYes? If the latter is accomplished, the former becomes trivial.
- TomSwirly 5y agoWhat?! Why? How will settling Mars or any planet save the biosphere? We have a few decades to not kill the planet. Settling another planet would take centuries.
- DoreenMichele 5y agoI think the idea they are suggesting is that if we can figure out how to terraform Mars and create a livable atmosphere from scratch, the tech and domain knowledge created along the way means cleaning up our atmosphere should be easy in comparison. Kind of like Olympic gymnasts lift weights and work on flexibility and they want to exceed what their performances require such that the performance is easy and not pushing them to the limits of their ability. Ie "You have to crawl before you can walk. If you learn to run, walking becomes trivial in comparison." If that makes sense.
- 5y ago
- jonplackett 5y agoHow much energy would that be for that trip, for a reasonably sized space ship to take care of a crew for that long? Are we talking miniature fusion drive or antimatter type energy density required?
- Johnny555 5y agoI haven't done the calculations (which would be hard to do without knowing how big/heavy the ship needs to be), but I'd assume it's going to need something well beyond our current technology. An aircraft carrier is powered through the water (horizontally, of course) for 25 years on nuclear power. Now imagine the power it would take to make it hover for 25 years, and that's your 1G ship.
- NortySpock 5y agoYou could do the "spinning drum" kind of 1G gravity, and save fuel that way.
- rootusrootus 5y agoYou still need something like the 1G acceleration, though, for the travel part. If you want it to happen within a single human lifespan.
- Johnny555 5y agoWithout the 1G of acceleration, you're limiting how far you can go in a single generation. At 0.1g, that 1000 light year trip would take 90 years (to those on the ship). The beauty of 1G is that it provides normal gravity and you can go great distances in a human lifespan. Of course a 2G trip will get you there in half the time, but it's harder for humans to live at 2G. Though maybe the time to the destination is not a problem if you don't mind a generational ship where generations of humans live (and die) on the journey. It doesn't matter to those on earth, since the trip will still take over 1000 years in their timeframe, so whether it's 1015 years, 1100 years or 2000 years probably doesn't really matter to them.
- davedx 5y agoNot true. Generating energy is only part - propulsion is hard too. Even if you had a bunch of anti-matter, how do you build a spacecraft that can safely transport humans for years with a propulsion and storage system that uses it? How do you use M-AM annihilation usefully? It’s not like Star Trek.
- BelenusMordred 5y agoWith antimatter propulsion you'd want to use it as its generated rather than the messy business of trying to store it.
- Johnny555 5y agoJust having a chunk of anti-matter isn't really "solving the energy problem", obviously you need to harvest the energy, but I think that given nearly unlimited energy, propulsion is a much easier problem to solve. One possibility is: https://en.wikipedia.org/wiki/Robert_W._Bussard#Bussard_ramjet https://en.wikipedia.org/wiki/Robert_W._Bussard#Bussard_ramj...
- BelenusMordred 5y ago> a lot of the detrimental effects of long-term space travel are eliminated Apart from the fact that everyone you know is now dead and if you returned home you'd basically be a living caveman museum piece.
- nynx 5y agoJust solve the aging problem first. That seems to be pretty close at hand anyhow.
- AnIdiotOnTheNet 5y agoIt seems to me the most likely scenario is that we perfect the ability to copy minds into an electronic computer system. Such a digital mind would no longer need most of the resources a human body would and could potentially last nigh-indefinitely. It would also be able to take advantage of both >1G (no flabby meat body) and <1G (no aging) constant accelerations. Further, a colonization effort by digital beings would only require raw resources to build more electronics and starlight for power, which expands the number of habitable places from "planets with human survivable conditions" to "basically anywhere near a star".
- arcanon 5y agoIt seems trivializing and like an existential crisis to have all of a humans being encoded in a computer. Once you have that, why even keep it running for all time as it is? Its just a version of software you could make changes to. We are probably not as glorious as we could be to become immortal as we are.
- kybernetikos 5y agoAre there any software, hardware or cloud providers currently existing that you would trust to run your consciousness?
- robotresearcher 5y agoWhy does this seem ‘most likely’ to you? I don’t see current tech that points this way at all. We don’t even have broad agreement on what a mind is beyond the the everyday folk notion. What are we to copy?
- ben_w 5y agoEnergy is the biggest problem, but it’s far from the only one. Consider the ISM: at 0.086 c, ionised helium is the same thing as 14 MeV alpha radiation. Low density regions within the galaxy are 0.2–0.5 particles/cm^3; 0.2/cm^3 * 0.086 c is ~5e12 particles/m^2/second, or about 9.9 watts/m^2 if it was all He4 and therefore 14MeV/particle or about 2.5 W/m^2 for Hydrogen at the same speeds, which is bad enough given what keeping that up for years will do to any solid hull, but molecular clouds can be 10^2-10^6 particles/cm^3 and the upper bounds of that is ~10 MW/m^2. Even without Relativity (which makes it worse), if you double the speed the kinetic energy per particle quadruples and you also double the number of particles per unit time.
- trhway 5y agoionized particle moving in your frame can be recovered as energy while the particle itself can be used as reaction mass (He) or even as fusion fuel (H).
- ncmncm 5y agoFirst, you have to ionize it all.
- ClumsyPilot 5y ago"ionized particle moving in your frame can be recovered as energy" You also recover it's momentum, which means you slow down. Really you are recovering your own kinetic energy, you are breaking against the interstellar medium, probably very violently and destructively. That's like saying "a building was moving in the frame of reference of the plane, so it didn't crash - it recovered energy." A more advanced version of this concept is known as Buzzard ramjet, and it was calculated to be energy negative https://en.wikipedia.org/wiki/Bussard_ramjet https://en.wikipedia.org/wiki/Bussard_ramjet
- soheil 5y agoCan someone do the math to calculate the energy needed for a ship like this to accelerate near the speed of light? I suspect the amount of energy may exceed what's available even if we were to capture all energy generated from the sun.
- jandrese 5y agoIt's not even the energy that is a problem, it is the mass. The rocket equation is a harsh mistress.
- soheil 5y agoBut more energy is the only thing that is needed when mass is increased, so not sure why it wouldn't all boil down to energy? Unless you're talking about escaping Earth specific gravitation.
- jandrese 5y agoAre you talking about kicking your reactant so hard that it picks up significant amounts of relativistic mass?
- soheil 5y agoHaha no but I'm not assuming the rocket equation is applied in Earth's gravitation, but maybe the spacecraft could be built far enough from any plants to be impacted by an initial gravitational field. If nuclear energy is used, it can be increased in less than linear change in mass.
- jandrese 5y agoRegardless of what you use for power a rocket has to eject mass from the rear to propel you forward. Newton's second law. The problem is that as you increase burn times (like years at 1G), you need to increase the amount of mass you are pushing out the back. But to do this you increase the mass of your rocket which means you need to push even more mass out and it becomes a vicious circle of exponentially increasing rocket mass. The idea of accelerating at 1G for the entire trip only works if you have a source of propulsion that doesn't obey Newton's second law. Otherwise there literally isn't enough mass in the galaxy to make it work. The caveat being that if you can somehow exploit relativistic mass to effectively multiply your fuel it might be possible, but my math isn't good enough to work it out. My gut feeling is that it would require an unreasonable amount of power however, even for an extremely powerful nuclear power plant.
- ClumsyPilot 5y ago>"If we could solve the energy problem" Energy is a fundamental currency of the universe, up to heat death. It's not something to be casually 'solved'. We are more likely to 'solve' hibernation, aging and death, and then we can travel to the stars with ease - current tech can get us there in a thousands years, and that isn't much in the grand scheme of things.
- nradov 5y agoCurrent tech is not durable or reliable enough to last anywhere near thousands of years without frequent maintenance and a supply of replacement parts. Even simple things like analog electric circuits with no moving parts degrade over time.
- ClumsyPilot 5y agoLaws of physics place hard limit on your speed, they don't do that for lifespan of your engine. It's an fundamentally easier category of problem. We have wooden ships that are hindreds of years old, and space doesnt have corrosion, erosion, saltwater, etc. Also you wouldn't send one guy in a box without spare parts, would you?
- grumpyprole 5y ago> Laws of physics place hard limit on your speed, they don't do that for lifespan of your engine. That cannot be true. Nothing escapes the laws of physics. It obviously depends on the engine, but for example current electronics have a lifespan of only a few decades. Even the half-life of DNA might be a problem, depending on the hibernation method.
- austern 5y agoI think some of the people responding to the comment about solving the energy problem are missing the point. There's solving the energy problem in the sense of finding an energy source that can power human civilization (preferably without melting the planet I live on, but that's a discussion for another thread). Then there's solving the energy problem in the sense of accelerating a spaceship to ultrarelativistic speeds. The latter is a very hard problem. A good rule of thumb to remember is that if you're going fast enough to experience large time dilation, then your kinetic energy is to be large compared to your rest mass. It's the same factor of γ=1/√(1-v²/c²) either way. So if you're traveling 1000 years in 15 years ship time, you've got γ=67 and your kinetic energy is 66 times your rest mass. Ouch! (And here I'm making the incredibly optimistic assumption that you aren't carrying your fuel with you, because if you are then you also have to expend energy to accelerate your fuel, and to accelerate the fuel you use to accelerate your fuel, etc.) If the rest mass of your ship is about the same as that of an aircraft carrier (the USS Enterprise, CVN-65, seems appropriate), then 66 × 86000000kg × (3×10×⁸ m/s)² = 5×10²⁶J. That's a lot. Nuclear energy in the ordinary sense is nowhere close to enough. This is thousands of times more energy than we could get with all the U-235 on Earth. Or we could imagine getting this energy from fusion, using the big fusion reactor located a cozy 8.5 light-minutes away from us. Earth gets about 123000TW from the Sun, so another way of looking at this number is that if we captured 100% of that energy, it would take us 130 years to get enough for the ship's kinetic energy. Accelerating big things to ultrarelativistic speeds isn't easy.