The muon has a mass of about 105 MeV.  U235 fission yield about 200 MeV per event.  So it seems possible if a transuranic atom is heavy enough.  I've never heard of it though.  It is so far beyond any radioactive decay mode that I really doubt it.

As far as other reactions you have the proton decay reaction that hasn't yet been detected.  That is of no practical use.  Then there is black hole radiation of the Hawking Effect.

-- Edited by John at 01:24, 2007-04-26

Andrew wrote:

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EDIT:
Another one:
I often heard about "plutonium" batteries. I know there are RTG's, which gain their power from the heat generated by decaying radioactive fuels. However, Plutnoium is a alpha decayer, and alpha decay has charge. Wouldn't it be somehow possible to convert this charge directly to electrical power?

-- Edited by Andrew at 20:47, 2007-04-25

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Yes, and there are some researches at NASA on alphavoltaic conversion.
http://www.rit.edu/~smhsps/power_conversion.htm

There are also some concepts of nuclear reactors (not RTG, real fission reactor) in which the kinetic energy of charged fission fragments is recovered by induction in a magnetic field.

And, it so happens that there is a version of string theory put forward by Lisa Randall at theoretical physicist at Havard that predicts that micro black holes may soon be created in particle accelerators.  She explains her theories in "Warped Passages" that attempt to explain this on a popular level.  Of course these object would only be detectable from the decay products.  But perhaps a micro blackhole could be eventually build an used a mass converter as Googlenaut suggests.  These very small objects could also be a chance to study quantum gravity.

I would imagine--I am no physicist, just a good imaginer--that the predominant particle radiated by blackholes undergoing Hawking evaporation should be electrons and positrons. Because of their relatively low rest energies, these should be the predominant particles emitted by the blackhole. Also fairly large quantities of pions, muons, with a lower percentage of protons and antiprotons should also be emitted.

I don't think it will emit anything really complicated--as this implies a very complex vacuum field event at the event horizon. A simple thermodynamic argument waving "Entropy" implies that you can get more disorder from 120 protons and neutrons free of each other than you can from one nucleus with a combined mass of 120 protons and neutrons. If that sounds like a vague argument--you're right. But in principle, my gut feeling is that a blackhole will evaporate more simple particles than complex ones.

Still, by placing a micro blackhole --or actually a whole series of them -- inside a reaction chamber lined with a good heat transfer medium like water, then almost all of those particles and antiparticles will eventually annhilate with their antipartners, and emit a lot of gamme-rays. If the water shell is thick enough, or if it filled with dense beads of tungsten or thorium oxide, then I see no reason why the evaporated mass of a black hole could not end up producing usable quantities of power by heating and boiling water with gamma rays, and spinning a turbine with the generated steam.

Well, by placing a lot of mass in a shell around the black hole, it won't really matter where the particles come out , what energies they have, or what kind they are. They will eventually annhilate with their antipartners, or they will decay. Each anhilation and decay process will release atleast one or two gamma-photons. If the material is dense enough to attenuate the gamma-photons, it will eventually deposit this energy as heat. Dense beads of thorium oxide, or even tungsten surrounded by a layer of carbon and then SiC ought to do nicely. The you can have a Hawking Reactor equivalent of a nuclear pebble bed reactor. Pump helium or nitrogen through the bed, and run that through a gas turbine. At high pressure and temperatures with helium, you're going to get the thermodynamic equivalent of about 50% efficieny--which is pretty darn good. And such a power conversion system could be scaled up to the Gigawatt level quite easily.

As far as trapping the electrons and positrons--sure using a strong magentic field this will cause charge seperation--negatively charge particles will tend to bend one way, and the positively charged particles will tend to bend the otherway. Dump the electrons, and store the positrons.

However pleasent the storage of antimatter may seem, however, it is still likely to be dangerous stuff to handle. And if it can be trapped and stored effectively especially in tiny storage volumes, this may lead to a whole new array of miniaturized nuclear-like weapons: very small, fairly low yield, and mostly clean weapons. Even tiny antimatter triggered thermonuclear devices. Good for propulsion perhaps, bad for incipient political climate. I don't particulary want the Iranians to get their hands on something that is better than nuclear weapons!



-- Edited by GoogleNaut at 15:46, 2007-04-28

My though is that you would have to put some electric change into it so that you could handle it with eletromagnetic  forces.  If the theory (Lisa Randell's longer strings) is correct you would have to have a super particle accelerator to like the new one a CERN to make them.  I think the current expectation is that they will just be a short lived resonance.  But if we could find some way to capture it, hold it, and "feed" it then it just might be possible to do this.  This reall is more of a science fiction or far off thing. 

I think that Arthur C. Clarke used a micro-black hole drive in this book Imperial Earth if I recalling correctly.

No, anti-particles wouldn't tear black holes apart. The would just be absorbed into the black hole.  Present theory is that gravity is all that is left to the outside universe is mass, charge, and angular momentum. 

-- Edited by John at 21:47, 2007-04-28

You need the accelerator to make the mirco-black hole then you need to capture it and move it to the spacecraft. The accelerator wouldn't be on the spacecraft.  I think that putting charge on it would be the best way to handle it.  One would need to keep puting matter into it so that it will have a stable radiation level and not burn out.

Micro blackholes that evaportate will convert a sizeable fraction of their mass into energy in the form of gamma-rays--given certain conditions. One of these conditions, is that they must be small. Now for blackholes, anything under a solar mass is small. What I am talking about, is a black hole with a mass of a few micrograms, or maybe up to a milligram. The thing will be unstable and will evaporate almost instantly.

Some mechanism for producing a whole series of blackholes must be found, either using an accelerator to produce them (which is interesting,) or some other means to cause a local collapse of spacetime. But these tiny blackholes must be force fed a matter stream before they evaporate, and that means that in order for them to grow (just alittle bit) they must temporarily recieve more matter input than they lose from Hawking evaporation. One hole cannot be used, because a black hole will of even a few miligrams will radiate with the power of the sun. Something like this can only be operated in pulse mode--so many holes per second must be made!

I was looking at an application of Miguel Alcubiere's "Warp Metric" and realized that if you can make something as fantastic as a space-time equivalent of a soliton wave, then it should also be possible to make spherically symmetric wave that propagates inward--in other words--an imploding shell that forces matter to 'gravitationally' collapse to a point, provided the shell is symmetric enough. This could be the mechanism to create a micro blackhole.

Careful scaling of the whole scheme should produce any power output desired. (From a few Megawatts up to Terawatt power levels, or even higher. How about a Petawatt 10^15 W! Now we're talking!)

O.K., for the hard part--anybody know how to create a spacetime metric?


-- Edited by GoogleNaut at 13:33, 2007-04-29

Not enough to be useable as a weapon. The thing will evaporate long before that happens. And besides, a one milligram blackhole at 100 m distance will have exactly the same attraction as a one milligram mass at 100 m. If the black hole were massive enough, then it might attract a vessel towards it--but only if the blackhole's mass was more than the ship...

it wouldn't do any good as some kind of projectile weapon because the hole will evaporate on a time scale approaching 10^-23 seconds or so. This is one hundred billionth of a trillionth of a second. Also, the amount of energy, while staggering from a single particle point of view, is probably not much more than a few tens of GigaJoules. A one milligram blackhole will not possess any more energy then half a milligram of antimatter for instance, and will liberate no more than 1/1000 of the energy release of the atomic bomb dropped on Nagasaki. So say no more than an 'explosive' yield of twenty tons.

Not to say however, that the radiations emitted by an evaporating black hole could not be used as a pump for something really nasty--like a 100MJ or 1 GJ X-ray laser--now we're talking powerful directed energy weaponry!



-- Edited by GoogleNaut at 00:08, 2007-05-05

Milligram blackholes will not leave the 'ship' they will evaporate in some containment structure. They don't last long enough to do anything else. You use the energetic eminations from an evaporating black hole to pump a set of helium cooled, single crystal lanthanum chloride rods which will lase in xrays. You point the rod bundle at whatever you don't want there anymore (making sure not to aim the recoil beam at anything important on your own ship!) and ZAP! It's flash fried!

A black hole big enough to physically gobble up a ship must have significant gravity some distance away from it--say hundreds of meters. Now we are talking the mass of a mountain or even a mountain range. How about a twenty kilometer asteroid. Trillions of tons of mass. You can't 'project' something like that--as the amount of mass needed to even control a black hole like that would be very substantial.

And if you could see the effects on a ship that got hit with something like that--well, I would imagine that you would see the ship physically implode in a fraction of a second, followed by a cataclysmic blue-white flash of volatilizing spacecraft structure evaporating from thermal x-ray emissions from the accretion disk surrounding the micro blackhole. If you didn't get instantly fried by that, then you'd see nothing, because not a shred of the ship would be left...


-- Edited by GoogleNaut at 18:41, 2007-05-05

-- Edited by GoogleNaut at 18:41, 2007-05-05

I'll see if I can either find or redo the derivation on the lifetime of classical microblackholes...

The trouble is that if memory serves, the minimum mass for a blackhole to survive one second is several million metric tons. What this means is that the last three quarters of a million tons will evaporate in a fraction of a second--which will appear as though it were a titanic nuclear explosion--a vast flash of energetic particles and gamma-rays is what you'll get. And the total energy liberated will be very close to the order of the entire solar output for the same 1 second duration--in otherwords, if you are anything nearer than atleast 100 million miles away, you're probably going to get more than just a suntan. And if you are only thousands of kilometers away--well forget it, your atoms will just be a minor contribution to an artificial 'solar wind,' a rather small smear of plasma where a ship and crew used to be. I definately don't recommend being near one that is massive enough to evaporate after 1 second.

There isn't much difference in time, on a human scale atleast, between the evaporation of a 100,000 metric ton black hole, or a 1 kilogram black hole, or even a milligram black hole--they all will appear to evaporate almost instantaneously, even though the milligram one will evaporate on time scales of a few trillionths of a trillionth of a second, and the 100KT blackhole will do so on the order of a few a milliseconds--still pretty darn quick by human standards.

And the energy librated will approach the mass-energy of the hole. So a one kilogram hole will librate energies approaching what a high-yield hydrogen bomb would produce--something in the neighborhood of 20 Megatons of TNT equivalent. Bigger holes will make bigger holes in the ground--so to speak!

Hawking once calculated that in order for a hole to have been created at the beginning of the Universe--not an entirely unrealistic possibility--then for a 3.5 billion metric tons hole created 14 billion years ago, the hole would be finished evaporating just about now, i.e., exploding. This was one of the original hypothesis regarding the mysterious gamma-ray bursts first detected in the late 1960's by the Vella satellites.

Silly question: I recall that there are particles called "neutrinos" and that they react with the nucleus of the atom. Where can I learn more of these reactions, their effects and so forth?

Yes, that and the links are quite enlightening, thank you.