Re: [math-fun] Science fiction (some of which is permanently gonna be fiction)
"THERE IS NO PRACTICAL WAY TO STORE A CHUNK OF ANTIMATTER." Somebody better tell NASA... http://www.bbc.co.uk/news/science-environment-14405122 Antimatter belt around Earth discovered by Pamela craft "Dr Bruno said that, aside from confirming theoretical work that had long predicted the existence of these antimatter bands, the particles could also prove to be a novel fuel source for future spacecraft - an idea explored in a report for Nasa's Institute for Advanced Concepts." http://arxiv.org/abs/1107.4882 ---- I've asked the following sort of question before on math-fun: I realize that matter annihilates antimatter when they come into 'contact', but what is 'contact' in this context, and what are the time sequence details -- e.g., when a molecule of glucose 'contacts' a molecule of anti-glucose ? At 07:05 AM 11/13/2011, Warren Smith wrote:
There's a lot of garbage science fiction out there that has nothing to do with science, especially in hollywood... but in this post I want to demolish two sci-fi ideas that occur in works of Larry Niven (et alia) which maybe did sound achievable to the naive. But a third such idea (super strong materials) will also be considered and argued to maybe have hope.
1. Sci-fi antimatter. You just keep a chunk of antimatter magnetically suspended in vacuum or something, where it's an excellent energy source for your super-rocket, ray-gun, also an excellent mega-bomb when you turn off the magnetic levitation. Stores the maximum possible amount of energy for that amount of mass.
Actually: let's say a single normal-matter gas atom contaminates the vacuum. Hits the antimatter. Boom. Way more energy is released than you need to eject some antimatter atoms at high speed. They in turn hit the normal matter container. Boom boom boom. The resulting normal atom ejecta fly out to hit more antimatter. Etc. This is an exponentially amplifying process.
THERE IS NO PRACTICAL WAY TO STORE A CHUNK OF ANTIMATTER.
Get over it.
On Sun, Nov 13, 2011 at 8:23 AM, Henry Baker <hbaker1@pipeline.com> wrote:
I've asked the following sort of question before on math-fun:
I realize that matter annihilates antimatter when they come into 'contact', but what is 'contact' in this context, and what are the time sequence details -- e.g., when a molecule of glucose 'contacts' a molecule of anti-glucose ?
Contact is occupying the same point in spacetime (to within a wavelength). -- Mike Stay - metaweta@gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com
On Sun, Nov 13, 2011 at 11:23 AM, Henry Baker <hbaker1@pipeline.com> wrote:
"THERE IS NO PRACTICAL WAY TO STORE A CHUNK OF ANTIMATTER."
Somebody better tell NASA...
http://www.bbc.co.uk/news/science-environment-14405122
Antimatter belt around Earth discovered by Pamela craft
--there is antimatter in the universe, including a big cloud of positrons near the center of our galaxy found by gamma ray telescope (how did it get there?)... but you can't store a chunk of it anywhere near you.
I've asked the following sort of question before on math-fun:
I realize that matter annihilates antimatter when they come into 'contact', but what is 'contact' in this context, and what are the time sequence details -- e.g., when a molecule of glucose 'contacts' a molecule of anti-glucose ?
--the outer electrons in the glucose and the positrons in the anti-glucose will combine on time scales on order of the positronium lifetime about 100 picoseconds. Then the nuclei will be able to coulomb-attract and fall into each other with no electrons in the way and the lifetime for that kind of "onium" ought to be even shorter.
Agreed, but "photon rockets" are pretty cool, because their specific impulse is better than any matter-propelling rocket.
I actually know of at least two ways to store energy at densities not much worse than the E=m*c^2 limit without antimatter: (a) fast-rotating black holes... (energy extractible using "penrose process" & related) (b) make a huge toroidal coil of superconducting wire and store energy in the form of a magnetic field. The energy stored goes like volume*field^2 while the mass needed goes like surface which for very large torus (size of solar system) is relatively negligible (most of the "mass" will be field energy). Unfortunately, in this scheme the magnetic "pressure" (proportional to field^2) even though you can make it arbitrarily small, will still over a huge size surface exert enormous force, apparently killing you for tensile strength reasons. But there is something called a "geon" invented by John Wheeler which used gravity as the bottle to confine photons (unstably, I believe) without matter needed. These (b) constructs would be huge, though. Related to (b) is something actually useful if they ever invent way-better superconductors -- we could build a huge energy storage deice on earth using a supercoil at tiny cost since only the surface costs, not the volume..., suggest locating Antartica... combined with global supeconducting energy transmission grid... thus solving issue with solar energy that the sun does not shine at night, sometimes cloudy, etc. You all may enjoy making some calculations about that.
participants (3)
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Henry Baker -
Mike Stay -
Warren Smith