Space race seems to be heating up again

Unfortunately, we do not, but if a way to produce it is developed, using it to initiate fusion reactions might be a better way to use it. Otherwise it's a very inefficient way to store and release energy.

 

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You might called it "fusion" but "anhilation" would be more accurate.

As the anti-matter is destroyed, you would get back the energy that made the anti particle, but not the energy you expended to make it. Not by a long shot as running the "making machine" (very likely an accelerator of great size, thousands of big electro-magnets and many vaccuum pumps, etc.) would consume millions, if not billions, of times more energy.

These machines are extremely inefficient as energy converters. Converting great quantities (thousands of kilowahtt hours) into a few hundred joules, at most! (I am just guessing at the numbers because whether it is a "losing proposition" by only a factor of only 10,000 instead of by 10,000,000,000 is not very important.)

What is important is to understand that it is great nonsense to think that you can get net energy from anti-matter you must make.

PS as anti-matter anhilates generally only gama rays are produced (Always I think) and they are useless for "initiating fusion" as they would hardly interact with the fusion gas or plasma, while passing thru it more esaily than X-rays would.

 

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Billy, better physicists than you think it will work.

 

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proof?

 

http://ffden-2.phys.uaf.edu/213.web.stuff/Scott Kircher/fissionfusion.html

 

University of Alaska professor suggesting of such?

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hehehee...and what mathematical proof is there on his page? ...see none... And what is the rank of this University of Alaska amongst engineering and physics degrees? hmmm...dont see it in top 100's...for sure.


Sure....here is a take on: "I am Bob, I got phD in astrophysics from JuggyBuggy college in Zimbabwe" ... "and I, Bob, say that we can have antimatter engine propelling us to far universes. " Now I am going to go look after my goats for now..."

 

Uh huh, and how do we make anti-matter? Oh yeah, we use incredibly energetic events in particle accelerators, and hope to find some amongst the products.

And luckily, there aren't clouds of anti-matter close by that we can harvest, because that would be really quite dangerous.

So, where does the anti-matter come from, to be used as fuel?

 

As people in Africa and other places around the Earth starve to death or

don't have any potable water to drink.

 

Well, the devil is in the detail. Maybe an anti-matter engine is hypothetically possible. Doesn't mean we could ever make it practical. This is where some folks get carried away, like that nuclear bomb powered Orion spaceship. Sure, the numbers work, but in practice? :-/

 

In practice nuclear power won't get the ship moving any faster than

conventional engines. They only last longer.

 

This reference's ideas are not nonsense, only extremely far fetched -i.e. highly unlikely to be either attractive or achievable reguardless of cost etc. for at least a dozen decades. You simply did not understand and mis-stated some of the facts. Thus, your post stated nonsense. I.e. in post 81 you said that "using it {anti-matter } to initiate fusion reactions might be a better way to use it." The physicists of your reference are good enough physicist to know that is IMPOSSIBLE, for the reason I gave in my post 82. Namely the gama rays produced when an anti-proton annhilates with a proton of their fuel drop would not significantly interact with light elements like deterium or tritium, but pass thru these fusion gasses very easily as if they were not even there.*

With high atomic number elements, like Uranium (A=92, from memory) not only does each atom have many more electrons which could inter act via Compton scattering, but more importantly the inner shell electrons are in the very deep potential well of the 92 positive protons and thus more likely to be ejected by a gamma. Still not very likely, I think, as even the binding energy of the two intermost n=1 electrons is probably still much less than the energy of the gammas - i.e. still far from any resonance interaction. However, if a few gammas did interact with uranium, ejecting electrons from inter most shell they might cause significant recoil of the uranium nucleus. (I will not bother to check if this is even possible, but just assume the physicists of the reference have and my doubts about it even being possible are invalid.) If it should then collide with another uranium nucleus, then FISSION (not fusion as you said) could be produced. This is what your reference said.

It may only require one (or a few more realisticly) such FISSION events to cause secondary nuclear reactions. That first FISSION will typically result in two moderate mass FISSION fragments, and few fast neutrons. The absorption coeficients for these 2 or 3 fast neutrons in other uranium atoms is very low, so perhaps after a several dozen collisions with the light fusion gas atoms, they will be slowed down form their initial (17 Mev, I think, from memory) energy they can cause other U235 to undergo FISSION, (If they do not escape for the "fuel drop" first). If enough FISSION reactions could be achieved, then the energy released could elevate the fusion gas atoms to 100,000,000K temperature and then, just as in the "hydrogen bomb," it is at least conceivable that a tiny fraction** of the fuel drop might under go fusion. Thus, your reference is not completely nonsense, but your misquoting / (mis understanding of it?), is complete and total nonsense, again.

I will add more, in addition to what already said above, as to why I think this an extremely far fetches idea, even leaving the lack of economic attractive ness aside. (Much better to use conventional nuclear reactor to drive a much simplier lighter weight ion engine, for one example, of a "mission to a star" spacecraft.) The problem of producing the anti- matter on board would seem to totally impossible - hugh massive accelerators are required and even if by some miracle, a "bread box" sized system for generating them were to be discoverd, the energy required to make them (due lack of 100% efficiency of that "bread box") would be more than released when the annhilated. Alternatively, if made on Earth, how are they to be stored on the space craft until the annhilation is desired? They can not touch any thing, so not only is their storage chamber a perfect vaccuum (not possible near and out gassing space craft) but will require lots of continuous energy imput. Perhaps laser radiation light pressure pushing them forward with the same acceleration as the space craft has or a strong magnetic field gradient. Even if the long term trend to drift into the storage chamber walls were not a problem, the fact that the accelerating space craft would "run into the stored anti-matter" if it is not also CONTINUOUSLY given EXACTLY THE SAME acceleration as the space craft has. This alone is a very great challenge, with men walking around inside the space craft, comunication antennas turning, heat transfer liquids being moved, etc. This simple fact alone probabaly renders the entire idea useless, in practice for a trip to a star, even if the many, many more techinical problems could be solved! One brief failure of the co-acceleration driver or of its sensor / control system on the way to the star, and "By-By space craft" as the stored anti-matter hits the storage chamber wall!

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*These gammas would be photons with with about one billion electron volts of energy - I.e. more than half would pass thru several centimeters of lead without any interaction, I think, but will not bother to check. Certainlyfor every one which did interact with fusion gases, hundereds of trillions of these gammas would have no interaction with atomic H,D, or T as these three hydrogen isotopes all have only a single electron to Compton scatter them. I am 99% sure that is the the dominate interaction possible, but these gammas are so extremely energetic it is possible there may be some excited state to the D & /or T nucleii, which by chance permits a resonate energy interation with the nucleus.

**Because in atomic bombs the material is first given great convergent inertial (High explosives surrounding the nuclear matterial grealy compress it far above normal solid density.) it stays togther long enough for a small part to undergo nuclear reaction. Also the main secrete of A-bombs is how to make a lot of neutrons inside before the nuclear reaction starts and blows the nuclear matterial apart - failure to do this is probably why the N. Korean A=bomb was such a dud. The referce does not even try to compress the fuel and give it inward inertia first. - I do not know the correct number, but surely 99.99% or more of their fuel drop would just be blown apart with out any nuclear reactions. I.e. even it it worked, it would be very low efficiency way to accelerate a space craft.

 

Ah, I was referring to that nuclear bomb powered fiesta that some dude used to rant on about here, don't know if you saw the thread? Great in theory, until you realise that while lifting the rocket was taken into consideration, manouvering it wasn't, ... so stopping, and getting into any orbit would be tricky.

 

Except, of course, for the minor fact that you have to launch them to the moon in the first place - which is going to cost a lot more than simply launching them on a sub-orbital ballistic path to your enemy's city. That more than cancels out any potential economic savings. I can't believe this discussion went on for so long without anyone pointing that out.

 

Seriously. Also, even if some country was dumb enough to try to station nuclear missiles on the moon, there'd be nothing to stop various other countries from firing their own nukes at the moon sites and destroying them. The only way it could ever work is if you already had a permanent moon base, and were producing nuclear weapons, missiles and propellants there. Which is pretty much ridiculous.

Is Metakron the same guy that suggested some time back that China could defeat the United States by building thousands of airliners, stuffing them full of army troops, and trying to fly them across the Pacific for a land invasion?

 

I recall that conversation. It also was saying that every so often the ship

while traveling in space would have to detonate a nuke in order to maintain

thrust. That detonation would blow the ship apart if I remember right.

 

Except that it is extremely hard to pinpoint a site on the moon if the owners of that site do not want to be found.

Yes, China could stuff enough troops into crap-built planes to defeat the U.S. They have had the U.S.'s cruise missile technology for over ten years now, and to be fair, everyone has had the cruise missile jet engine for about that long. It's called a "human wave" tactic and they have excess males. Now maybe you could come up with some kind of rebuttal that amounts to something a little more cogent than the usual dicksizing that goes on around here.

 

Billy, your rant about that didn't even make sense, OK?

 

I really did not expect you to understand. You rarely do and have never thanked me for expaining the physics, but that is OK as most, if not all, of my posts correcting your nonsense are only an effort to help OTHERS, who know little physics, not be badly mis-lead. You are clearly a "lost cause" when it comes to learning or rational thought.

PS to quadraphones, yes - that airborn humman wave attack on US from China* was just one more of his nonsense posts. I did not comment on it because the stupidity of it is very obvious to all and because there is no false physic in it requiring correction.

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*MetaKron seems to be very paranoid about China. He has also posted that the Chinese have already planted many atomic bombs in US buildings! IMHO, he needs psychological help.

 

Not really. Even ignoring all the chances of divulging the locations in the process of rocketing things to the moon and doing construction there, others could simply put automated imaging satellites in lunar orbit to ferret them out. Similarly, the earth is a lot bigger, and has a lot more man-made objects to discriminate between, but space-fairing powers have no trouble mapping and targetting one another's fixed ICBM sites.

Moreover, you don't have to pinpoint the sites. Since there is nobody living on the moon, and no atmosphere, you can simply attack the moon sites using warheads with massive megatonnage. It's not as though a few more craters on the moon are going to matter.

Or rather, enough to feed lots of fish in the Pacific Ocean after the US Navy and Air Force finish playing target practice with them. Even if some slipped through, they'd have no place to land and no way to resupply. Not to mention that China would already have come under devestating counterattack long before the planes got anywhere near Hawaii, let alone the mainland.

I already wasted more time than I care to admit rebutting that idea back in the original thread. You remember, the one where lots of people ridiculed you for suggesting something so blatantly stupid? If you want cogent rebuttals, I suggest you forward some ideas that aren't ridiculous on their faces.

 

You wouldn't know what was ridiculous anyway.