As far as I know, there are no 'confirmed' cold fusion reactions.

One would think that the if such things were possible, then they may follow the same routes as 'ordinary' fusion: so there are no special 'cold fusion' reactions, only fusion reactions that occur at 'surprisingly frigid temperatures,' and they are 'catalyzed by unknown means.' If they exist at all!

After all these years, the jury is still out on cold fusion. Back in my community college days, a chemistry professor was going to take some of the school's platinum and palladium foil and attempt to duplicate Stanley Pons and Robert Fleischmann's orginal experiment. There was a lot of excitement in those days. However I pointed out to him that he needed to be cautious: that if fusion was indeed occuring at the rates being reported (hundreds of watts) then the neutron flux generated (24 trillion per second) ought to be enough to kill everyone nearby. This gave him pause: he told me he hadn't even thought of that. For safety's sake, I suggested putting the experiment in a large sealed container and relocating it to the 16 foot deep end of the school's swimming pool with instrument and power cables leading up to a rolling experiment bench somewhere up top. This apparently killed the idea of an experiment, but it does illustrate the point: if fusion was actually occuring at those rates, then why didn't the University of Utah have two dead scientists that the nigh****chmen would discover some hours later...?

The lesson I learned from all of this was: in science it is good to be pessimistic. It is also O.K. to be cautiously optimistic. It is best to be cautious and evaluate the consequences of a success--before the experiment is undertaken--because the immediate consequences of success might be death or injury! When dealing with fusion, all of the reaction products including the energy production must be accounted for. Radiation is something that needs to be respected and prepared for.

O.K. I'm off the soap-box!

Neutrino reaction enhancement: I wish I knew how to do that, because enhancing the coupling of neutrinos to ordinary matter would be very, very useful! For a neutrino telescope, this would be in effect like having a nightvision equipment coupled to an ordinary telescope. This would be very useful.

Unfortunately, (or fortunately looking at it another way) neutrino interactions are governed by the Weak Nuclear Force, and so their interactions with ordinary matter are very, very weak. Infact, at this very moment, a torrent of neutrinos is flashing harmlessly through all of our bodies: billions of them each second, with nary a whisper. Neutrinos are like ghosts almost: they can flash through light-years of ordinary matter without interacting with anything...

Years ago I did an interesting calculation: if we could 'see or feel' neutrino energy, then the 12 second long 'neutrino' flash from Supernova 1987A in the Large Magellenic Cloud, 160,000 light-years away, would have been brighter than the noon-day sun on a clear, blue sky. Which means, for 12 seconds, things would have gotten pretty warm for us if we could feel neutrinos! There is only one place in the universe where neutrino pressure amounts to anything: and that is in the iron core of an imploding star! As the core collapses, the degenerate electrons are forced into the iron-nuclei where they interact with the protons there: the result is that the protons become neutrons and emit scads of anti "electron neutrinos." The flux of these neutrinos is so great that they literally 'blow' away the outer iron core--infact the shockwave is so violent that at this moment all the heavy elements above iron are formed including the uranium, thorium and lead! Not too bad for 'ghost.'

Muon-catalyzed fusion works--it's been demonstrated by passing slow Muons into liquid deuterium. But it doesn't generate enough fusions to be useful in power generation. There have been various proposals to use muons to catalyze fusion, but the half-life of muons is small enough that no more than a few dozen fusions can be catalyzed before the muon vanishes. If several thousand or tens of thousands could be catalyzed, then we might have something there...

Even the small fusors like the Farnsworth StarFusor can produce harmful fluxes of neutrons. Our physiology makes us very susceptible to damage from neutrons--I don't know why--but neutrons are generally very harmful to us. So even a burst of 10^11 neutrons from a single burst from a commercial neutron generator tube is harmful. Maybe not fatal--immediately--but harmful enough that it can increase the risk of cancer. Several bursts might cause significant damage to bloodforming tissues and various membranes...so you've got to watch out with neutrons. And those commercial neutron generators typically produce no more than a few hundred picowatts of fusion power...

Neutrinos in a science fiction reactor...hmmm. I don't really think so. Again, their interactivity (in particle physics this is called "coupling") with matter is governed by the weak force--they seem to have an intrinsic aversion to any interaction with matter. Years ago I joked with a friend of mine on a camping trip about what 'color' would a gluon flashlight emit? We came to the conclusion that if a way could be found to generate something like a beam of concentrated 'gluinos' the hypothetical supersymmetric 'neutrino-like' counterpart to the gluon the carrier of the strong nuclear force, then it could be possible to stimulate ordinary quarks in matter to change their 'color.' This doesn't sound like much--but the results on matter would be catastrophic: it would literally cause ordinary matter to boil away into a soup of electrons, positrons, pions, mesons, and scands of nuetrinos. The pions and mesons would eventually decay into gamma-rays, and the electrons and positirons would also find each other and annhilate into gamma-rays as well...matter would be more or less instantly converted into energy... Pretty slick, I think!


The conclusion we had was that this must have been the real 'mechanism' behind the Death Star Laser--it wasn't really a laser at all, but a 'gluino beam' which was 'green' (of course!) The beam intersects the matter of a planet, and converts a few million tons of it into energy. Voila--one obliterated planet! No problemo!






-- Edited by GoogleNaut at 08:44, 2007-06-20

Well, I don't know about that. Neutrinos can't be 'harvested' like wheat. The combined neutrino flux from the sun and cosmiv sources--though numerically great--the power flow and hence momentum passing through an arbitrary surface is surprisingly small. Only when one is near the core of a imploding massive stellar core does the neutrino flux impart substantial momentum on matter. Infact, in these regimes the mass-energy associated with neutrino fluxes can be volumetrically 'denser' than ordinary matter--that is a lot of mass flow: and it moves at almost the speed of light.

Infact, I can imagine that in those regimes, the momentum-flux caused by the neutrino burst can be so high, that space-time is literally dragged along. In that case, matter will flow with it. This might even be an enhanced 'coupling' method for neutrinos coupling to matter--I don't know. But the little that I do understand of general relativity does suggest that neutrino induced frame-dragging may result in acceleration of matter near the outer core of an imploding star. This is the origin of the Type II supernova.

Neutrinos are mysterious little particles that interact so weakly with matter that their existance was originally surmised from observations of particle tracks in bubble chambers or cloud chambers. The momentums of input particles did not always sum up to the momentums of the outgoing particles: sometimes there was a defecit. This deficit had specific energy and momentum profiles which allowed physicists to hypothesize the existance of a new neutral particle. The neutral particle had to have a very tiny rest mass and appeared to zip along at the speed of light: it was called the neutrino which literally means: "neutral small one."

Neutrinos can sometimes strike an atom of something like Chlorine-37 causing a neutron to split into a proton and an electron. The electron is expelled by the collision, and the resultant Argon-37 nucleus has too few neutrons to be stable: so it decays into something else...

The particular flash of energy from that decay is what we detect as a 'collision' with a neutrino. In a 1000 metric ton tank of cleaning fluid, dichloroethane, one of these 'collisions' occurs no more than once or twice a day. It is very very hard to detect neutrinos: even the flux from a nuclear reactor is hard to detect, because the detector would literally be larger than the reactor!

Another random question: Say we have a pure fusion engine with very high Isp. Would it be possible to direct the rocket exhaust so it can disable an ICBM?

Bussard has some ideas of using fusion for high Isp, low thrust and low fuel usage engines, as well as something called QED (Quiet Electric Discharge, use the high DC gained from aneutronic fusion to make relativistic electrons that you shoot into a medium like water). What can I make of this? Also, what sound would a rocket give if it's engine's exhaust velocity exceeds the speed of sound?

Regarding materials, what is the best internet source to learn about them?

GoogleNaut wrote:

---

Muon-catalyzed fusion works--it's been demonstrated by passing slow Muons into liquid deuterium. But it doesn't generate enough fusions to be useful in power generation. There have been various proposals to use muons to catalyze fusion, but the half-life of muons is small enough that no more than a few dozen fusions can be catalyzed before the muon vanishes. If several thousand or tens of thousands could be catalyzed, then we might have something there...

Even the small fusors like the Farnsworth StarFusor can produce harmful fluxes of neutrons. Our physiology makes us very susceptible to damage from neutrons--I don't know why--but neutrons are generally very harmful to us. So even a burst of 10^11 neutrons from a single burst from a commercial neutron generator tube is harmful. Maybe not fatal--immediately--but harmful enough that it can increase the risk of cancer. Several bursts might cause significant damage to bloodforming tissues and various membranes...so you've got to watch out with neutrons. And those commercial neutron generators typically produce no more than a few hundred picowatts of fusion power...

Neutrinos in a science fiction reactor...hmmm. I don't really think so. Again, their interactivity (in particle physics this is called "coupling") with matter is governed by the weak force--they seem to have an intrinsic aversion to any interaction with matter. Years ago I joked with a friend of mine on a camping trip about what 'color' would a gluon flashlight emit? We came to the conclusion that if a way could be found to generate something like a beam of concentrated 'gluinos' the hypothetical supersymmetric 'neutrino-like' counterpart to the gluon the carrier of the strong nuclear force, then it could be possible to stimulate ordinary quarks in matter to change their 'color.' This doesn't sound like much--but the results on matter would be catastrophic: it would literally cause ordinary matter to boil away into a soup of electrons, positrons, pions, mesons, and scands of nuetrinos. The pions and mesons would eventually decay into gamma-rays, and the electrons and positirons would also find each other and annhilate into gamma-rays as well...matter would be more or less instantly converted into energy... Pretty slick, I think!


The conclusion we had was that this must have been the real 'mechanism' behind the Death Star Laser--it wasn't really a laser at all, but a 'gluino beam' which was 'green' (of course!) The beam intersects the matter of a planet, and converts a few million tons of it into energy. Voila--one obliterated planet! No problemo!






-- Edited by GoogleNaut at 08:44, 2007-06-20

---

About muons : as you say, muon-induced fusion is attractive only if we have muons available, but it is very energy-consuming to produce them and they decay quite fast.

Once I imagined trapping negatively charged muons into the electric potential of very big (exotic) isotopes ; that would prevent their decay if the binding energy is larger than the muon mass. From calculations on the back of an envelope, I got the result that we need at least 200 protons in such a nucleus... which is not reasonable.

Also, one of Andrew's first questions was id a super-heavy isotope could decay into a muon ; I do not think so, because the 106 MeV constituting the muon mass must be available counting the difference between the mass of the initial isotope and the masses and kinetic energies of the decay products ; for that you need to break apart the big nucleus (something like fission) and in such a process most of the released energy is carried off by the pieces, and very little is available for the muon. 

About GoogleNaut's question why neutrons are so harmfull to us, the answer is that they go through the whole body (contrarily to alpha particles which are stopped very fast for instance), and when they do interact, it is always via the strong interaction with a nucleus, and such interactions release lots of energy in a very small volume ; so the probability for an irreparable chromosome damage is large.

Your hypothesis of a beam of gluinos is silly : gluinos (if they exist), like their gluon counterparts, are not color-neutral (they are green as you justly point out), and for that reason they are never found as standalone particle ; they are always confined into hadrons.

About micro-black hole, you might be interested to read the latest simulation results obtained by the ATLAS collaboration at CERN :

http://www.hep.phy.cam.ac.uk/~parker/atlas/BH_CSC_Note/BH_CSC_paper_v5.pdf

From this paper we have at least an answer to a question adressed earlier in this thread : the particles produced by the black hole evaporation are as much electrons and muons as quarks (which make hadron jets), with multiplicities in the order of 10.

 

A rather bizarre suggestion: how would it be possible to cleanse an entire planet?

If you clobbered the Earth--let's say--with something as big as Ceres--then that would be it: the end of the world as we know it. The surface would be melted all the way down to the upper mantle--nothing would survive. It would be just about as catastrophic as the gigantic impact 4.5 billion years ago when a Mars sized body slammed into proto-Earth and the resultant orbiting debris coalesced into the Moon and the Earth.

If you have powerful enough space drives, then slamming even a small nickel-iron asteroid moving at an appreciable fraction of the speed of light would probably do it. Even a million metric ton asteroid (50 meters or so across,) accelerated to a gamma=3 or 4 (94% to 97% light-speed) would possess sufficient kinetic-energy to possibly dismantle an Earth-sized body: the released energy would be comparable to the entire Sun's energy output for one second, and this should exceed the gravitational binding energy of an Earth-massed body.
 

Any impact big enough to puncture a hole through the crust (ten miles thick) would likely be big enough to incinerate, smother, and then bury anything on the surface. Even the Chixilub impact of 65 million years ago--the one that is thought to have caused the dinosaurs to become extinct--didn't punch all the way into the mantle.

Also, don't think of the Earth as solid. Think of it as a bag of jello with a relatively thin, hard crust. An impact on the surface will cause seismic waves to oscillate through the bulk of the planet--a really big impact, big enough to fracture the crust at the impact site--will likely have similar consequences on the antipode where the seismic waves all meet at the opposite side: more crust fracture, instant gouts of magma on the surface, and mountain ranges thrust up over a few seconds. In fact, there have been a couple of theories floating around about just this sort of thing in relation to impact generated extinctions--it's not necessarily the impact that causes the extinction--that sets the stage. It's the one-two punch of a huge volcanic event that follows immediately after a large impact--it is thought that this is the mechanism which may have caused atleast some of the largest basaltic flood eruptions in the ancient past: the Siberian Traps (Permian Extinction event) and the Deccan Traps of India (which coincided with the time if the Cretaceous Extinction Chixilub impact--and is geographically located very suspiciously near the antipode of that impact. Coincidence?)

http://www.mala.bc.ca/~earles/siberian-traps-ptr-jun02.htm
http://www.google.com/search?hl=en&q=siberian+traps&btnG=Google+Search

If you wanted to cause more or less instant sterilization of a region, select the right sized bolide for the job: anything big enough to cause a fireball that completely engulfed the area you wanted to whack ought to be good enough to sterilize it (whether mechanical or biological)--of course there will be other, more wide spread effects as the result of that impact.

There is a really neat program which allows you to throw around some big rocks and see what happens: it calculates the possible effects of large impacts on Earth.

You can use it online at: http://www.lpl.arizona.edu/impacteffects/

It's really fun to do what ifs--but it is also interesting to realize just how much energy is involved with some of these impacts. Some of the bigger impacts make nuclear explosions look like a sparkler compared to a bonfire--the energies involved with even Chixilub sized event will approach 100 million Megatons of TNT--imagine a fireball over 100 miles across!