Fusion vs. Antimatter vs. Gravity

[PrimeCruncher]

Originally Posted by Fusion_power

There is one method of energy release that is much more efficient than fusion. Anybody care to guess what it is? rettamitna (backward)

I believe we've created that substance. It lasted for about a trillionth of a second before coming into contact with normal matter and going FOOM. Still, it WOULD be cool to have Star Trek-like M/AM reactors powering the world...

[jinydu]

Antimatter was first created in the 1930s, quite some time ago. Today's particle accelerators can create many billions of antimatter particles and store them indefinitely (although this consumes a lot of electricity, and hence, a constant flow of money). Still, it is nowhere near enough for an antimatter engine. If all of the antimatter was annihalated, the total amount of energy released would be on the order of tens of joules.

Even worse, the amount of energy needed to create antimatter is MUCH greater than the amount of energy released by annihalating it with ordinary matter. Since antimatter doesn't last very long in nature, the only way of obtaining it is to create it. Obviously, this requires the same amount of energy as destroying it, and that assumes the process is 100% efficient (obviously an invalid assumption).

It seems the only way to build a workable antimatter engine would be to find large stockpiles of antimatter in nature, an unlikely scenario in the near future.

[PrimeCruncher]

Originally Posted by jinydu

Today's particle accelerators can create many billions of antimatter particles and store them indefinitely (although this consumes a lot of electricity, and hence, a constant flow of money).

Magnets consume that much energy? Seriously, have you ever read "Angels and Demons" by Dan Brown? It's an excellent read, as are his other three books. A scientist created a whole bunch of antimatter and stored it in these special bottles. The bottles are a vacuum, the only thing inside is antimatter. There are magnets on each end of the bottle that keep the antimatter suspended so that it won't touch normal matter and annihilate it. This is, of course, the exact same theory of antimatter storage used on Trek...

[Uncwilly]

Originally Posted by jinydu

Antimatter was first created in the 1930s, quite some time ago.

I hate to speak off topic, but I believe (do correct me if I am wrong) antimatter occurs in certain naturally occuring radioactive decays. This would mean that people first created it in the 1930's.

[jinydu]

Originally Posted by Uncwilly

I hate to speak off topic, but I believe (do correct me if I am wrong) antimatter occurs in certain naturally occuring radioactive decays. This would mean that people first created it in the 1930's.

That's right. Huge numbers of positrons are being produced in the sun every second (but they don't last long). They just weren't detected until the 1930s.

There's a reaction called beta-plus decay. If I remember correctly, a proton turns into a neutron and emits a positron.

All known reactions that produce particles also produce an equal number of corresponding antiparticles.

[clowns789]

In Guinness the biggest antimatter producer is Fermilab in Illinois and it makes 100 billion protons of antimatter every hour. Also I was going to ask about nuclear fusion. It can release more energy than required to make it, but the magnetic fields to contain it in a power plant would use more energy. So containing the energy is the only problem.

[xilman]

Originally Posted by Fusion_power

There is one method of energy release that is much more efficient than fusion. Anybody care to guess what it is? rettamitna (backward)

Another one: gravity.

More energy is emitted during the collapse of a stellar remnant to a black hole than was emitted during the entire lifetime of the star. Even collapse to a neutron star liberates more energy than the lifetime of fusion. The star spends ages fusing protons into neutrons and emitting energy, then fuses the remaining protons into neutrons in the course of a few minutes. T the energy of fusion is negative (at zero gravity the most stable nucleus is somewhere around Fe-56) but this is more than made up by the collapse under gravity and a very large explosion is the result.

Given an accessible rotating black hole (I don't ask for much, do I?) something like 30% of the rest mass of an object thrown into it can be extracted as useful energy by the thrower.

Paul

[Fusion_power]

Thats an interesting reply Xilman. We have 3 basic forces: Gravity, Electro-weak, and Strong Nuclear. Each can release huge amounts of energy under the right conditions.

As you described, gravitational collapse triggers a manifestation of the strong nuclear force that releases huge amounts of energy in a very short time. This is not a "gravitational" energy release, it is just gravitationally triggered. Even though a huge amount of energy is released in a very short time period, it is still a fusion reaction and the amount of energy released is proportional based on E=MC^2.

Gravitional heating releases a large amount of energy over an extended time frame. Absorption into a gravitational point source such as a rotating black hole would also release huge amounts of energy (unfortunately, it might tunnel elsewhen in time so you might not be able to harvest it).

The Electro-weak force is involved in annihilation of opposite charged particles such as positrons and electrons. This is the basic matter/antimatter reaction.

The strong nuclear force binds charged particles together with conversion of a small amount of mass to energy in the process. Interestingly enough, it works by binding two protons for example creating a helium nucleus from two hydrogen nuclei. The resulting helium nucleus has slightly less mass than the two protons separately and that missing mass was converted to energy.

My point is this: The electro-weak works by annihilating particles that have similar mass but opposite charge. The strong nuclear works by binding two particles of similar charge and mass. Where are the particles that gravity works on?

Fusion

[xilman]

Originally Posted by Fusion_power

Thats an interesting reply Xilman. We have 3 basic forces: Gravity, Electro-weak, and Strong Nuclear. Each can release huge amounts of energy under the right conditions.

As you described, gravitational collapse triggers a manifestation of the strong nuclear force that releases huge amounts of energy in a very short time. This is not a "gravitational" energy release, it is just gravitationally triggered. Even though a huge amount of energy is released in a very short time period, it is still a fusion reaction and the amount of energy released is proportional based on E=MC^2.

Gravitional heating releases a large amount of energy over an extended time frame. Absorption into a gravitational point source such as a rotating black hole would also release huge amounts of energy (unfortunately, it might tunnel elsewhen in time so you might not be able to harvest it).

The Electro-weak force is involved in annihilation of opposite charged particles such as positrons and electrons. This is the basic matter/antimatter reaction.

The strong nuclear force binds charged particles together with conversion of a small amount of mass to energy in the process. Interestingly enough, it works by binding two protons for example creating a helium nucleus from two hydrogen nuclei. The resulting helium nucleus has slightly less mass than the two protons separately and that missing mass was converted to energy.

My point is this: The electro-weak works by annihilating particles that have similar mass but opposite charge. The strong nuclear works by binding two particles of similar charge and mass. Where are the particles that gravity works on?

Fusion

Unfortunately, your descriptions aren't entirely accurate.

Gravitational energy release does not require a large amount of time. Ever dropped a rock on your foot? That action certainly releases significant energy in a small time! As I said, gravitational collapse of a star to a neutron star really does take time on the order of a minute and it really does release more energy in that time than the star had previously radiated in its entire lifetime, some of which is used to convert protons into neutrons.

If we assume the Einstein field equations are at least a fairly good description of the behaviour of a black hole, and we have very little to suggest otherwise, then under the conditions I described the gravitational energy released can be used in the distant observer's (the thrower in my earlier post) present and position.

Matter/antimatter annihilation doesn't rely on the electroweak interaction. Even particles that don't interact by the electroweak force (assuming any exist other than the so far hypothetical graviton and gravitino) would undergo particle - antiparticle annihilation. A convincing explanation would require a foray into quantum field theory that most people here would not welcome.

Proton fusion to form helium take four protons, converts two of them to neutrons, positrons and electron neutrinos, and glues them together into a He-4 nucleus. There are several mechanisms but the p-p chain, which generates most of the Sun's energy goes like this:

p + p -> D + (e+) + nu_e + gamma
D + p -> He_3 + gamma
He_3 + p -> He_4 + (e+) + nu_e + gamma

I don't have easy access to all the Greek symbols, subscripts, etc, so I should explain the above.

p is a proton; D is a deuteron (one proton bound to a neutron); e+ is a positron or antielectron; nu_e is an electron neutrino; He_3 is a helium-3 nucleus, containing two protons and one neutron; He_4 is a helium-4 nucleus containing two protons and two neutrons; gamma is a photon.

The energy is produced as the gammas and the kinetic energy of the produced particles. The positrons will annihilate with local electrons and produce more gammas.

Next, neutron star collapse: as I said, the energy release is gravitational in origin and neither electroweak nor strong though, of course, it is converted into photons and kinetic energy of matter, as well as some gravitational radiation. Without the effect of gravity, the reaction which converts roughly a solar mass of protons into neutrons is strongly endothermic. The typical collapsing star is made up of stuff like C_12, O_16, Ne_20, Mg_24, Si_28, all the way up to Fe_56. To a very good approximation half the star is protons and the other half neutrons, with enough degenerate electrons around to maintain electrical neutrality. Fe_56 is at the bottom of the energy well and fusing the other nuclei to almost pure neutrons requires an input of energy. That energy comes from the gravitational collapse.

Electroweak does not work by annihilating particles and antiparticles. You are reading these word through the electroweak interaction between the photons coming from your screen and the electrons in your retina, to give just one example.

Whether gravity is mediated by particles and, if so, what they are and how many different kinds there are is still not understood by the theoretical physicists. If the gravitational interaction can be expressed in terms of quantum field theory, the basic quanta are generally termed gravitons, which are required to be spin-2 bosons. Some theories require fermionic counterparts which are then called gravitinos. None of the theories are generally accepted, as far as I know.

Finally, E=mc^2 applies to all forms of mass-energy.


Phew, this is seriously off-topic. Apologies if anyone objects, but I felt I couldn't let the misconceptions stand unchallenged in a public forum.


Paul

[PrimeCruncher]

Originally Posted by xilman

Phew, this is seriously off-topic. Apologies if anyone objects, but I felt I couldn't let the misconceptions stand unchallenged in a public forum.


Paul

On the contrary, I rather enjoyed reading about this stuff. Though maybe you SHOULD stop hogging this thread and start a dedicated one.

[mfgoode]

[QUOTE=Fusion_power]Thats an interesting reply Xilman. We have 3 basic forces: Gravity, Electro-weak, and Strong Nuclear. Each can release huge amounts of energy under the right conditions. ---- Where are the particles gravity works on? /unquote

Like uncwilly I dont usually comment on off topic subjects, so this is an exception.
There are four basic interactions (forces)
1)Gravitational
2)Electro magnetic
3)The nuclear weak interactions
4) The nuclear strong "
Please check it on the web if you like, go to
http://www.creationofuniverse.com/ht...librium02.html
Gravitons: have been postulated
"Although most physicists accept the idea that the gravity field is really quantized, it is unlikely that the graviton - the quantum of gravity- will ever be detected -------
Gravitons interaction are simply too weak ever to be seen.
Strictly speaking,if a graviton should hit a proton the proton would recoil. But this recoil is so tiny, we can never detect it.
Gravity is the weakling of the quantum particle interactions"
Source: 'The Cosmic code' by Heinz R. Pagels

MallY