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There are a number of technologies for attaining velocity in addition to liquid propellants. Solid propellants have long been a mainstay of rocketry, from the sole source of thrust for amateur rockets to auxiliary thrust the Shuttle. However, solid rocket propulsion is ultimately subject to the nastiness of the rocket equation, as is propulsion from liquid ...


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Thrust is another name for force, and force is momentum per time. In other words, to get thrust it is necessary to generate momentum and to keep on doing it. Typically it consists of projecting matter (gas, plasma) away from the vehicle, and the momentum transferred to that matter results in equal and opposite momentum given to the vehicle. The faster the ...


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Since you mentioned liquid fuels explicitly, I feel obligated to bring solid-fuel rockets to your attention. They do not need to be cooled but once ignited, they can headly be stopped until they run out of fuel. Thus, they are primarily used as boosters to aid take-off. E.g. in the space shuttle, the thin white boosters attached to the orange liquid-fuel ...


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Assuming that by escape velocity you mean exhaust velocity, then the velocity comes from the Maxwell-Boltzmann distribution. This gives the velocity distribution of the particles in a gas as a function of temperature. For our purposes we can use the most probably speed, i.e. the peak in the distribution, as a rough estimate and this is given by: $$ V_e = ...


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Wormholes, if they exist, would allow faster-than-light travel and communication. However, there is currently no observational evidence for wormholes, only theoretical. The Alcubierre drive is a speculated device that would allow a spaceship to seemingly travel faster than light (from, say, the Earth's reference frame) by actually contracting and expanding ...


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Sending messages faster than the speed of light would also send them back in time, thus opening the door for all sorts of violations of causality - just google "Tachyonic Antitelephone". The use of such a device also requires the existence of tachyons, particles which have imaginary mass, and probably wouldn't interact with ordinary matter in normal ways. ...


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Anything you want can happen. The Alcubierre bubble isn't a thing that appears through ordinary physical cause and effect. It's a spacetime geometry that Alcubierre wrote down by fiat, computed the stress-energy tensor field of (which you can do for any geometry), noticed that it didn't match any known physics, and published anyway. So pick whatever you want ...


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It's easy after we rebuild ourselves first. We need to replace biological brains by digital brains. The problem we now have is that if we travel, we carry a biological machine that is much more advanced than the most powerful supercomputer we can build today, physically to the point of destination. This biological machine must always be kept at the right ...


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As @Danu said, the transit time is a massive problem. One of the comments to his answers mentioned that keeping the passengers alive might be difficult too. You need protection from meteorites, or the ability to take some losses and repair damage (as stated by @laovultai) protection from radiation i.e. solar wind when you're close(ish) to the sun an energy ...


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The link you posted refers to a design which would supposedly make use of faster than light travel. After reading this, I immediately stopped reading, since this is not possible. I don't care if it's a NASA-affiliated person who says this, it is simply misguided! Before continuing, I should draw your attention to the fact that I will not be discussing the ...



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