Quote from: KelvinZero on 06/25/2014 10:59 am... You are pushing directly against the moon for the whole trip......The big problem I see is what sort of beam you can focus on that range?The big problems I see:Wont it inflict the opposit push on the moon? How big is it considering the vast amount of energy mentioned before?Can you point it to the same direction of the traveling ship, while the moon rotates around the earth and sun?
... You are pushing directly against the moon for the whole trip......The big problem I see is what sort of beam you can focus on that range?
Well the total force, for example to push something the size of a skyscraper at 1g for 40 years, is the same as the force that such a skyscraper would apply to the earth by standing on it.
Quote from: KelvinZero on 06/27/2014 02:10 amWell the total force, for example to push something the size of a skyscraper at 1g for 40 years, is the same as the force that such a skyscraper would apply to the earth by standing on it.Except that the skyscraper also exerts the exact same force in the opposite direction simply by being there, due to a little something called "universal gravitation". Net thrust is zero.
or are you talking about a relationship between temperature and the spread of the beam?
I hope it is clear that what I mean by chemical-like includes NTR-like at an extreme end. It is what we can handle without unobtainium.
pps: Pulsed fusion is fine.. but if it were possible to launch those pellets from home, ie exploit beamed propellant, you would have all the same advantages but have converted the fuel requirements from exponential to n^2. When you are talking about interstellar velocities the difference has to be boggling. It just has to be.
eh; i know that some board member shy away from unproven physics like a vampire back pedalling from a crucifix but what about when this happens?
Quote from: KelvinZero on 06/27/2014 10:27 amor are you talking about a relationship between temperature and the spread of the beam?It's startling how fast a particle beam spreads out over interstellar distances when it's not really really close to absolute zero. The beam energy has to be ridiculously high for it to be even a little bit useful at a significant fraction of a light year.QuoteI hope it is clear that what I mean by chemical-like includes NTR-like at an extreme end. It is what we can handle without unobtainium.Now you're the one being uncreative. What's wrong with an electromagnetic receiver/nozzle? If we can handle beamed-core antimatter with a dozen or so tesla in a modestly-sized device, we should be able to handle just about anything on the scale of an O'Neill-type starship...And I repeat: Do the math. I did. If you confine yourself to chemical-like interaction energies, the base station requirements in terms of both mass per second and power become utterly silly. ...Quotepps: Pulsed fusion is fine.. but if it were possible to launch those pellets from home, ie exploit beamed propellant, you would have all the same advantages but have converted the fuel requirements from exponential to n^2. When you are talking about interstellar velocities the difference has to be boggling. It just has to be.Not unless you go to very high speed. In the vicinity of 0.1c, mass ratios for advanced fusion pulse schemes are in the range of single chemical rocket stages, if not lower, so the savings for using beamed power are modest and not enabling....Either way it wouldn't take much of a malfunction for a pulse unit to get slightly off course and smash into the starship......
If you don't want to discuss it, fine. But I will point out that it is not your thread.
.. remember that the title of this thread is "Constant acceleration at 1G and beyond"! I don't think any of what you would call sensible ideas come close to that.
I believe I have read that in space keeping a particle beam together is harder than a laser. in an atmosphere the bloom of a particle beam is partly mitigated by the surrounding atoms and molecules of the atmosphere. in space the electrical charges of the particles in the beam will repel each other and the beam will spread out. However i have also read an article some time back about a lab successfully creating a magnetically jacketed plasma in which case the particle beam could conceivably be kept together by such a jacket.http://www.sciencedaily.com/releases/2013/04/130416151931.htm
get out your crucifixes! http://physicsworld.com/cws/article/news/2014/jun/26/dwarf-planet-could-illuminate-the-dark-sectorSynopsis: a testable alternative theoretical model that allows for anti-gravity, does away with the need for dark matter, inflation and other more standard concepts. Antigravity iz reel!Noooooes! arrrgh!