Astrophysics For Dummies

[Tenspace]

The energy released from proton:antiproton annihilation (4.3 x 1013 cal per gram of antiprotons) is 1010 times greater than oxygen:hydrogen combustion and 100 times more energetic than fission or fusion. That is, one gram of antihydrogen (i.e., a “mirror” atom composed of an antiproton and positron (antielectron)) reacted with the same amount of normal hydrogen produces a total energy equivalent to that delivered by 23 Shuttle External Tanks (ET). (Schmidt, Gerrish, Martin, "Antimatter Production for Near-Term Propulsion Applications)

[Choobus]

brad89 wrote

I heard recently from my student teacher in chemistry that recent data (I believe from Fermilab) suggests that matter switches from matter to antimatter, like, a trillion times a second. Something along the lines of switching back in forth, a lot, in a short amount of time. I don't remember too well, it was a while ago he said it. Sorry I don't know more, but I thought it was interesting.

that is so retarded as to make jesus seem feasible. IUt's as wrong as wrong can be. You can get particle-antiparticle pairs pooping into erxistance in the vacuum, but it contravenes all known conservation laws for matter to simply turn into antimatter. Your teacher is a fucking idiot.

[Choobus]

There are two reasons why antimatter is a "better" source of energy than, say , nukular energy.

1) you can dig up your nukular material. Antimatter does not exist near matter (it can't) so it has to be made. Since this is always going to cost more in energy than you will get back it is not a good source of energy at all. This means that it's only useful when you need a high energy density, like on a spaceship.

2) In a nukular reaction less than 1% of the total rest mass is converted into energy. In a fission or fusion reaction you are still left with other elements that contain most of the energy you started with. You only get the difference in the binding energy out. In an antimatter reaction 100% of the rest mass is converted into energy. For positron-electron annihilation you get two gamma rays (usually) with 511 keV energy each. An electron weight ~ 9E-31 Kg. That means when an electron and positron annihilate you get 1.8E-30kG converted, which gives you E = mc^2 = 1.6E-13 Joules. To run a 60Watt light bulb for an hour you need 216000 Joules, so you would need to create (assuming electrons are free) 2.7E18 positrons to run your light bulb on antimatter power. The bestest positron beams in the whole wide world can only make 1E10 positrons/sec so you would have to run your beam for 2.7E8 sec, which is a little over 8.5 years. Seems like a lot of effort to run a lightbulb. And it gets worse if you use antiprotons or some other antimatter because leptons have no internal structure (we think) so they are the easiest to make. (no chain reactions to worry about). So, unless you can open a rift into another dimension or something and get your antimatter for free there is no chance of it being a useful source of energy, and practically no chance of it being a useful way to store energy.

there are lots of other useful things you can do though.

[Tenspace]

Choobus wrote

there are lots of other useful things you can do though.

Like antimatter BECs? Anitmatter lasers? Enlighten us, please.

[Choobus]

Well, for one thing, antimatter is extremely sensitive to electrons, so you can use positrons to probe the electronic structure of solid state materials in a unique way. Also, positronium is a purely leptonic system, but it has energy levels like hydrogen, so you can perform extremely sensitive spectroscopic tests on the atomic energy levels and you don't have to make any approximations of the internal structure of the proton like you do for hydrogen, so it allows very stringent tests of QED. (except you really need the BEC for that because it makes the experiments orders of magnitude more sensitive). A gamma ray laser could be used to ignite a fusion reaction. Presently they are building a huge X-ray laser to initiate a fusion reaction in a dense DT pellet. (NIF, national ignition facility) but they can't scale it up because the lenses keep getting destroyed by the laser pulses. The gamma ray laser will do the job in a room the size of an average house instead of the size of a football stadium like NIF. And it is quite scalable. In space you could build a gamma ray laser powered by a nukular warhead (one shot deal). This would allow you to tranfer about 20% of the energy of the warhead in a coherrant gamma ray laser beam, obviously moving at the speed of light. This could be useful to brerak up approaching space dragons/asteroids etc, or to decimate specific locations on the earth without all that nasty radiation.

[Philboid Studge]

Dude, if mu isn't a constant we can trust, then all bets are off. Maybe the laws of physics were written by white males to establish a patriarchal power structure?

[Choobus]

Philboid Studge wrote

Dude, if mu isn't a constant we can trust, then all bets are off. Maybe the laws of physics were written by white males to establish a patriarchal power structure?

I think it's pretty well established that physics was developed to impress chicks. that's why scientists tend to be such studs.....

After all, what woman could resist a paper with the title "A Study of Two Hemispherical Masses Oscillating in a Harmonic Manner in a Uniform Gravitational Field"? :P

[Choobus]

logarithm wrote

After all, what woman could resist a paper with the title "A Study of Two Hemispherical Masses Oscillating in a Harmonic Manner in a Uniform Gravitational Field"? :P

how else could they oscillate in a uniform gravitational field...........

[Tenspace]

ROFL!!!

CHoobus, have you heard of Scriptural Phsyics? :lol::lol:



Scriptural Physics is a method of acquiring fundamental knowledge about the physical universe that is guided by principles found in the Bible. Physics itself is the study of the interaction between matter and energy. More generally, it is a search for the fundamental rules that govern the physical universe.

[Tenspace]

Oh, man. These guys are great...

2. The atom smashing experiments show how the atom breaks up, not how it is put together. Ducks are not made of quacks just because quacks come out of ducks. Alpha particles, beta, and gamma rays are also common disintegration products, but physicists do not regard them as "parts" of the atom.

[Choobus]

Fucking jokers!

"He who waters will himself be watered"—Proverbs 11:25

really? Does that mean he who pisses himself will be pissed......

[Tenspace]

Choob, I'd love your comments on the table at the end of this article: http://members.dancris.com/~bfraser/4v4a/ATMORNUC.html

I read somewhere that antimatter was identical to matter in all form except charge, meaning that whether the particle is matter or antimatter is only a matter of perspective in relation to the dominant charges of particles in our universe, and that a universe could have just have easily been formed of anti matter and what we call matter would be the anti matter of that universe. Is that at all correct?

And if so, why matter and not anti matter?

[Tenspace]

SolidusSpriggan wrote

I read somewhere that antimatter was identical to matter in all form except charge, meaning that whether the particle is matter or antimatter is only a matter of perspective in relation to the dominant charges of particles in our universe, and that a universe could have just have easily been formed of anti matter and what we call matter would be the anti matter of that universe. Is that at all correct?

And if so, why matter and not anti matter?

Yes, and the "why" has to do with a slight imbalance of matter over anti-matter at the beginning of the universe.

If the quantities were exactly the same, then annihilation would have turned all matter into energy. Lucky for us there was asymettry in the production of matter & antimatter.

I think this conundrum was solved, but it's been awhile since I read the physics behind it. I'm sure someone will refresh my memory. :)